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08abf9e8c303077e4292141faf8222a0 | 101 543 | 5.7 Magnetic fields | TR 187 020 [i.2], which had been circulated for Public Enquiry, included a statement saying that RFID tags were susceptible to damage from magnetic fields. There was no independent reference in the document to support this statement so it was decided to carry out a test to investigate if it was correct. A LF tag was placed in close proximity to a calibrated coil. The maximum range at which the tag could be measured both with and without a current passing through the coil was compared. Since LF is the closest frequency to d.c. it was considered unnecessary to repeat this test at HF and UHF. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6 Test procedures and results | Both before and after the tests, measurements were made of the noise floor levels at each of the three frequencies of interest. The results are shown on table A.5. These levels were considered typical of what might be experienced in the environments where RFID systems would be deployed. A description of the procedure for carrying out each of the tests together with details of the test results is provided below. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.1 Reading range | Tests on the reading range at each of the three principal operating frequencies were performed in accordance with the Test Plan. Details on each of the tests are provided below. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 11 |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.1.1 Reading range for LF systems | A loop antenna of approximate dimensions 40 × 80 cm was positioned so that its centre was level and parallel with a wooden table. The loop antenna was connected to a Nedap 120 kHz interrogator. The field generated by the loop when powered by the interrogator was measured and found to be 59 µA/m @ 10 m. A ruler was laid along the length of the table. With the loop antenna energised by the interrogator, a tag in its optimum orientation with respect to the loop was moved slowly towards the antenna. See figure 1. Figure 1: Measuring reading range at LF The distance at which the tag was first read by the interrogator was recorded. The tag was moved slowly away from the loop until it just ceased to be read and the distance was again recorded. This procedure was repeated three times. The same process was repeated for a further nine tags. The results from the measurements are shown in table A.1. It will be seen from the results that the average range of an LF tag under the test conditions described above is 88 cm. Also there was only a difference in reading range of about 2 cm when moving the tag towards the loop and moving it further away. Based on a very small sample size, the vast majority of LF tags would have reading ranges of between 82 cm and 93 cm. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.1.2 Reading range for HF systems | These tests used a loop antenna configured in the form of a figure of eight as supplied by Nedap for their library system. The centre of the lower loop was arranged to be level with a wooden table. The loop was connected to an interrogator operating at 13,56 MHz. The field generated by the loop antenna was 53,5 dBµA/m @ 10 m. With the interrogator set to transmit continuously, a vicinity tag in its optimum orientation was moved slowly towards the loop antenna. See figure 2. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 12 Figure 2: Measuring reading range at HF The distance at which the vicinity tag was first read by the interrogator was recorded. The tag was moved slowly away from the loop antenna until it just ceased to be read and the distance was again recorded. This test was repeated three times. The same process was repeated for a further twenty four vicinity tags. The results from the measurements are shown in table A.2. The average range of an HF vicinity tag under the test conditions described above was 82 cm. Also there was only a difference in reading range of about 2 cm when moving the vicinity tag towards the loop and moving it further away. Although the sample size was small, a large population of HF vicinity tags could be expected to have reading ranges of between 85 cm and 78 cm. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.1.3 Reading range for UHF | These tests were performed using the Nedap uPASS Reach interrogator, which combined the functions of antenna and interrogator within a single case. The unit was arranged to be at the same height as a wooden measuring table as shown in figure 3. Figure 3: Measuring reading range at UHF The conducted power from the interrogator was measured at 27,7 dBm, which was equivalent to a radiated power of 33,25 dBm e.r.p. The equipment operated in the band 865 MHz to 868 MHz. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 13 The tests on reading range were performed on three different designs of retail tag. With the interrogator switched on, a tag in its optimum orientation with respect to the transmission was moved slowly towards the coil. The distance at which the tag was first read by the interrogator was recorded. The tag was moved slowly away from the interrogator until it just ceased to be read and the distance was again recorded. This procedure was repeated three times. The same process was performed for a further ninety nine tags. The results from the measurements are shown in table A.3. The average range of an UHF tag under the test conditions described above was 345 cm. Also typically there was only a difference in reading range of about 3 cm when moving the tag towards the loop and moving it further away. Although the sample size was small, large populations of UHF tags could be expected to have reading ranges of between 372 cm and 315 cm. During the course of the tests at UHF, it was demonstrated that the reading range was affected by a number of factors. For instance the nature of the material to which the tag was attached could modify the performance. This was particularly apparent for objects containing either water or metal. Mis-orientation of the tag from its optimum alignment and changes to the environment also reduced the reading range. For example it was shown that the movement of people in the immediate vicinity of the interrogation zone could have a noticeable effect. It was also demonstrated that shielding of the tag by means of aluminium foil prevented the tag from being read. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.2 Write range | Tests to measure the distance at which it was possible to write to a tag were carried out at LF, HF and UHF. A description of each of these tests is provided below. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.2.1 Write range at LF | These tests were performed using a purpose made writing unit. A picture of the equipment is shown in figure 4. . Figure 4: Measuring write range at LF Tests on the maximum range at which it was possible to write data were carried out on five tags. The tags were progressively moved further away from the antenna until writing was no longer possible. The range at which this occurred for each tag is summarised in table A.4. The typical maximum write range was 4,6 cm with no tag functioning above 6 cm. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.2.2 Write range at HF | At HF it was possible to write to a vicinity card using the same equipment set up as used for the reading tests. The maximum range at which it was possible to write data was measured for five vicinity cards. The results are shown in table A.4. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 14 Typically the write range for a HF vicinity card was 60 cm with the vast majority of cards having a write range of less than 80 cm. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.2.3 Write range at UHF | Measurements of the write range at UHF were performed on a prototype interrogator. See figure 5. Figure 5: Write range equipment at UHF Conducted measurements on the prototype interrogator showed that it was set to a level of 28,1 dBm, which was equivalent to a transmitted power level of 34,6 dBm e.r.p. This exceeded the permitted limit by 1,6 dB. Measurements were made on a sample of five UHF retail tags taken from the same batch that had been used in the tests for reading range. It was immediately apparent that the reading range was considerably greater than what had been recorded previously. Measurements were therefore made for both the reading and write ranges. These are summarised in table A.4. From the results it can be seen that the average reading range had increased to 8,6 m with one tag achieving a figure of 9,75 m. In all cases the maximum write range was approximately 1 m less than the read range. Subsequently an investigation was made into the differences in reading range between the two types of interrogator. The Nedap design engineer said that the receiver in the uPASS Reach interrogator had been designed with a sensitivity of typically -62 dBm. This level had been selected because it met the needs of the intended applications. The prototype interrogator had a sensitivity that was estimated to be at least 10 dB greater. It was also explained that the retail tags used in the tests contained the latest design of integrated circuits manufactured by Impinj. The sensitivity of these integrated circuits has been improved allowing them to operate at approximately 2,5 times the range of the first generation devices. However, because of the improved sensitivity the signal received at the interrogator has to be increased to hear the tags at maximum range. From theory if the power level of the prototype interrogator was reduced from 34,6 dBm to its maximum permitted limit of 33 dBm e.r.p, its reading range in free space would be reduced by 17 %. Using the average figure for range of 8,6 m in table A.4, this would equate to an adjusted average range of 7,2 m at 33 dBm e.r.p. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 15 Nedap provided a sample of a tag that was intended for use with their uPASS Reach interrogator. When tested in its optimum orientation in free space it was just possible to achieve a read range of 7,0 m. This showed that, during the tests in clause 6.1.3, the uPASS Reach interrogator had been receive range limited and explained the reduced reading performance. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.3 Illicit reading | These tests comprised a set of scenarios covering concerns that have been raised over the threats posed by RFID to privacy and security. A description of the method of test and the results for each scenario is provided below. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.3.1 Illicit reading of the contents of shopping bags | All of the tests were carried out at UHF. Three shopping bags, coloured orange, white and blue respectively, were each filled with five identical tagged items. In order to optimise the conditions for most favourable reading, none of the tagged items contained any water or metal. See figure 6. The identity number of each of the tags was recorded. Figure 6: Contents of tagged items in shopping bag A handheld reader (figure 7) was used to simulate the illicit reading of the contents of the shopping bags. Figure 7: Hand held reader ETSI ETSI TR 101 543 V1.1.1 (2011-04) 16 In the initial tests reading was attempted first with a stationary person carrying a shopping bag and then with the same person walking across the room. In both cases it was necessary to bring the handheld reader within 60 cm of the shopping bag before the contents of the bag could be read. During this test the lady carrying the bag commented that the reading process had represented an intrusion into her personal space. The test was modified so that the shopping bags were carried by three people walking side by side. The first person carried a bag in the left hand, the centre person in the right hand and the third person in the left hand. Thus two of the bags were immediately adjacent to each other. In order to read the tagged items, the hand held reader was passed immediately behind the bags at a distance of about 60 cm. The results are shown in table 1. Table 1: Analysis of illicit reading of shopping bags Serial No Tag number Colour of bag 1 AD99210442528F92600000DF O 2 AD99210442527D8F5F0000DC B 3 AD992104425249915D0000D7 B 4 AD992104425249925E0000D6 B 5 AD9921044252918F610000DE B 6 AD9921044251E590630000CA W 7 3005FB63AC1F3841EC880467 B 8 AD9921044252A990620000E2 O 9 AD9921044252758E5F0000DB W 10 AD99210442527B92600000DD O 11 AD9921044251E391630000CB W 12 AD99210442529790610000E0 O 13 AD9921044252618C5D0000DA W 14 AD992104425259935E0000D9 W Key: B = blue W = white O = orange From the table it can be seen that only 14 out of the fifteen tags were read. Perhaps of greater interest is that the order in which the tags were read was apparently random. Thus it would not be possible from the results to say with any certainty which items were in each of the bags. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.3.2 Containers with pills | In a second scenario UHF tags were attached to two plastic bottles and to a carton, all of which contained pills. The pills in the carton were encapsulated in packing with a silver foil backing. See figure 8. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 17 Figure 8: Tagged bottles and box of pills A bottle was placed in each of two ladies handbags. Using the hand held reader the tags could be read inside the handbags at distances between 65 cm and 90 cm. The reading range of the carton of pills was measured with the tag facing the reader (i.e. the silver foil furthest from the reader). In this setup the tag could be read in free space at a distance of 23 cm. With the carton placed in a lady's handbag and the silver foil facing the reader, it was not possible to read the tag. However when the carton was rotated so the tag was no longer shielded by the silver foil, the achievable reading range increased to between 80 cm and 120 cm. The reason for this increase was not immediately clear and was attributed to the undisclosed contents inside a lady's handbag! |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.3.3 Proximity cards | A further scenario included reading both the proximity tag in passports and in RFID transportation cards (such as the Oyster card). Both types of tag operate at HF using the ISO/IEC 14443 [i.3] technology. Reading the tags was performed using the NXP CL RD 701 (general purpose) interrogator. In all cases the reading range was less than 10 cm. It was explained that both tags incorporated security features, which protected them from being interrogated by normal commercially available equipment. In the case of the passport it was not possible to recover the data in the tag without first transmitting an algorithm based on the machine readable code printed on the page containing the personal details of the holder. For the transportation card it was necessary for the interrogator to initiate an encrypted dialogue with the tag. This was believed to provide sufficient security to prevent illicit reading by a non-professional criminal. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.3.4 Airline label tag | A separate measurement was made of the reading range of an airline label tag that is used to route and identify a passenger's baggage. The measurement was carried out using the uPASS Reach interrogator, which gave a reading range of approximately 4 m. If the measurement had been repeated using the prototype interrogator it is very possible that the reading range would have been in excess of 10 m. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.3.5 LF tags | Finally two LF tags were measured using an interrogator provided by Texas Instruments. One of the tags was intended for the identification of farm animals and was approximately 30 mm in length. Normally it would be used either in a plastic eartag, or put into a ceramic housing for use as a ruminal bolus transponder for cattle or sheep or inserted under the skin. The second tag was designed for use in the key fob of a car as a security measure. The coils in both tags were wound on ferrite cores. The tags were read using a loop antenna that was approximately 70 cm × 40 cm in size. This was significantly larger than would normally be used for the above two applications. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 18 With the tags held in optimum orientation approximate reading ranges of 30 cm and 15 cm were recorded for the animal tag and key fob tag respectively. Subsequently it was discovered that another LF interrogator was operating in an adjacent room. When this was switched off, the range of the animal tag increased to 50 cm. This demonstrated very effectively the susceptibility of RFID systems to ambient noise. Frequently the maximum ranges quoted by manufacturers are significantly greater than the distances that can be used for reliable operation. It was explained that the animal tag contains only a fixed number. This same number is also held in a central database. Identification of the animal can only be achieved by access to the database. However simply knowing the number would be sufficient to enable movements of the animal to be tracked. Since the key fob tag is intended as an anti-theft device it incorporated a number of security features. In normal use the tag operates at very close range so monitoring its response from outside the car would be technically difficult. In addition the system uses an authentication technique known as DST (Digital Signature Transponder) and includes a rolling code. It was comforting to note that although the interrogator was able to read the demonstration tag, it was unable to read the tag in a key fob owned by one of the supervisors. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.4 Eavesdropping | These tests were designed to measure the distance at which it would be possible to detect the response from a tag that was being activated by another RFID system. The tag responses were measured using conventional high quality laboratory equipment, which were able only to indicate that a tag signal was present. In order to decode the signal it would have been necessary to develop special purpose-built receivers. It should be noted that the distance at which it is possible to read a tag is always less than the distance at which it is possible to detect its presence. The measurements were performed at LF, HF and UHF. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.4.1 LF and HF tests | The measurement method for monitoring the tag responses at LF and HF was the same. A Rhode and Schwartz loop antenna was connected to a Rhode and Schwartz measuring receiver. The interrogator was set-up to activate an adjacent tag continuously. The response from the tag was most effectively detected as an audible signal at the measuring receiver. The maximum distances at which it was possible to detect the various types of tags are summarised below. Table 2: Maximum distances for eavesdropping with LF and HF tags Type of Tag Distance - metres LF systems Standard card for LF use 2,6 HF systems Vicinity cards 3,5 Passport 2,6 Oyster cards 3,0 6.4.2 Measurements at UHF Measurements at UHF were made using a log-periodic antenna connected to a spectrum analyser. The response from the tag was best viewed as a data stream on the display. Since the responses from the tags at UHF were true radio waves, they could be detected at much greater distances than were possible at HF and LF. With the uPASS Reach interrogator set-up to activate continuously an adjacent retail tag, the measuring antenna was orientated to receive maximum signal. The distance between the tag and the measuring antenna was then progressively increased until it was no longer possible to see the data stream on the spectrum analyser. It was demonstrated that it was possible to detect the response from the tag at distances up to 100 m across an open space immediately outside the Nedap building. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.5 Detection inside buildings | The tests were carried out in a mock-up of a room inside a house using first the uPASS Reach interrogator and then the hand held reader. A retail tag was attached to a box of chocolates. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 19 The interrogator was positioned at a distance of approximately 15 cm from the outside wall of the room. The interrogator was directed at the wall and switched on in continuous read mode. With the tag on the box of chocolates nearest the interrogator and in optimum orientation, it was held at a distance of about 20 cm from the wall and moved until it was read. It was then moved slowly away from the wall until detection was lost. This occurred at a distance of about 1 m. The box of chocolates was then moved back to a distance of 20 cm from the wall and moved laterally until reading ceased. This took place for movements of approximately half a metre on either side of the optimum reading position. An attempt was made to read the tag through the wall using the hand held reader. This proved not to be possible. However the tag could be read by the hand held reader through the glass of the door to the room at a distance of about 5 cm. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.6 Combined EAS/RFID system | A typical EAS/RFID system operating at UHF, such as might be seen at the exit from a shop, was set up in the meeting area. The system was switched on and a shopping bag containing five tagged items was carried through the gate to verify that it raised an alarm. A hand-held reader also operating at UHF was held close to the exit of the gate and activated. The shopping bag with the tagged items was again carried through the gate. There was no apparent detrimental effect on detection of the tagged items for both the gate system and the hand held reader. The test was repeated with the hand-held reader held on the "approach side" of the gate with the same result. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 6.7 Magnetic fields | The test was performed at LF only using a calibrated coil of 171 mm × 147 mm consisting of 40 turns. When a current of 5 A was passed through the coil it generated a magnetic field of 1,432 A/m. The test was carried out with one of the air cored passive tags that had been used in the previous tests. For the tests the system was configured so that the tag was separated by a distance of approximately 2 cm from the surface of the coil. See figure 9. Figure 9: Set-up for magnetic field test The tag was placed in optimum orientation with respect to the loop antenna. With no current passing through the coil, the tag was moved to a position where it could only just be read by the interrogator. Without moving the tag a current of 5 A was passed through the coil. It was noted that the presence of the magnetic field had no effect on the reading range. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 20 |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 7 Visits to operational installations | The test programme included visits to two operational sites that were equipped with working RFID systems. These were at the public library at Doetinchem and to the Metro Future store. Reports on these visits are provided in annex B. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 8 Analysis of results | It was recognised from the outset that the test environment was assumed to be typical of what might be found in operational installations and that the results were therefore no more than indicative of what might be experienced in practice. The results for reading and writing ranges showed that the performance of tags in free space is remarkably consistent. However there is a considerable difference in the performance of inductive systems (LF and HF) and those operating at UHF. Although the reading range of tags at UHF is greater, they are affected more by the items to which they are attached and by their orientation. Also reading performance is more sensitive to the immediate environment. For example transmissions are easily reflected or shielded and are modified by the presence of people/objects moving in the immediate area of the interrogation zone. All systems are influenced by the presence of ambient noise. Due to the influences described above, for acceptable performance RFID systems are usually designed to operate well within the maximum limits specified by the manufacturers. Typically the maximum usable ranges for most LF and HF proximity systems are less than 60 cm. For vicinity systems operational ranges are of the order of 2 cm to 5 cm. For systems at UHF reading ranges up to 5 m are realistically possible, although very often systems are designed with ranges of about 3 m. In very many applications the data in the tag remains unchanged for much of its life. Modification of the data on a regular basis is confined largely to industrial installations and to high security applications such as financial transactions. In the latter case the operational ranges are of the order of 2 cm to 5 cm. Illicit reading with a portable reader is possible at ranges of up to 60 cm. This is sufficiently close to be uncomfortable for the intended victim. Reading tags carried by a single person in an open space may therefore arouse suspicion. On the other hand in situations where a number of people, all carrying tagged items, are in close proximity with each other, it would be very difficult to determine which tags are being carried by each person. Alternatively illicit reading may be performed using a fixed long range interrogator. For this to be effective the interrogator would have to be coupled to a second device such as a CCTV camera. Also unless the activity was carried out in a quiet area, it would be difficult to identify which individuals were carrying tags. Greater reading ranges (up to 1,2 m) using a hand held reader were possible for tagged cartons of pills in ladies handbags, although this was dependent on the way in which the cartons were positioned. The reason for this is not understood and might represent an area for further study. The very short operational ranges of vicinity cards and key fob tags make them unlikely targets for illicit reading. Additionally they are further protected by means of authentication and encryption techniques. However they may be a target for professional criminals who might develop alternative means of attack. Technically eavesdropping would be possible at all three frequencies. However the limited distances at which this could be achieved at LF and HF makes this less likely. On the other hand, given a clear propagation path, it would certainly be possible covertly to read the contents of UHF tags at significant distances. However the value gained from this activity is questionable. Without multiple receivers located at different locations, it would be very difficult to determine the position of the tag that had been read. This would necessitate a clear propagation path to the tag for each receiver. The situation would be further complicated if there were multiple RFID installations in the same area. This could mean that tags from the different installations could respond simultaneously. Unless there were substantial differences in the signal strengths received from the different tags, it would be impossible to decode them and determine their positions. It is important therefore to evaluate carefully both the value to the attacker and the extent of the risk posed by eavesdropping. Based on the results the probability of reading tagged items inside a house from outside is likely to be low. The tagged items would need to be close to an outside wall and in optimum orientation with respect to the antenna held by the attacker. Also given the attenuation of the signal through the wall, the attacker would need previous knowledge of the positions of tags in order to read them. Many criminals might well consider that the difficulties involved did not justify the effort. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 21 It should be remembered that some of the tests inside a house were carried out using the uPASS Reach interrogator and a tag containing an Impinj chip. As was discovered during the writing tests, this was not the preferred combination. It may be prudent to repeat the tests with another RFID system. The tests on the EAS/RFID system showed that it was unaffected by the immediate presence of a handheld reader. The tests showed that a strong magnetic field had no detrimental effect on reading performance. This test was carried out using an LF tag that was constructed with an air core. It might be instructive to repeat this test using a tag with a ferrite core. |
08abf9e8c303077e4292141faf8222a0 | 101 543 | 9 Conclusions | Based on the results and the subsequent analysis, the following conclusions may be drawn from the tests. The tests covered a wide range of scenarios and generated a lot of valuable information for use by the STF. The tests demonstrated that there is a clear difference in the characteristics of inductive RFID systems (LF and HF) and systems that operate at UHF. These differences should be taken into account during the work of the STF. The risks attributed to illicit reading are probably less than had previously been thought. The responses from tags operating at UHF can be read at significant distances. The STF should assess very carefully the extent of the risks that this creates for the privacy and security of the public. The tests could find no evidence that a high magnetic field can cause damage to RFID tags. The results from the present document could be used to identify areas for more detailed investigation in future tests. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 22 Annex A: Results recorded during the tests A.1 Results of reading tests Table A.1: Reading range results for LF tags Serial No. In (cm) Out (cm) In (cm) Out (cm) (cm) Out (cm) In (cm) Out (cm) 100 83 90 83 92 85 88 83,67 90,00 99 87 91 88 89 86 89,5 87,00 89,83 97 88,5 88,8 86,5 87 85 87 86,67 87,60 96 87 87,5 85 88 85 86 85,67 87,17 95 88 89 87 88 89 89 88,00 88,67 94 90 91 90 91 91 92 90,33 91,33 93 87,5 89 88,5 91 91 91,5 89,00 90,50 92 86 89 86 89,5 87 90 86,33 89,50 91 88 91 87 91 87 88 87,33 90,00 90 87 90 89,5 91 86,5 88 87,67 89,67 Arithmetic mean 87,17 89,43 Standard deviation σ 1,82 1,28 Two standard deviations 2σ 3,64 2,56 Max read range of approx 95% Upper 90,81 91,98 of tags will fall between Lower 83,53 86,87 1st measurement 2nd Measurement 3rd Measurement Mean range Table A.2: Reading range results for HF tags Serial No. In (cm) In (cm) In (cm) In (cm) In (cm) In (cm) In (cm) In (cm) 1 80 80 79,5 79,5 79,3 82,5 79,60 80,67 2 80,3 80,5 80,2 78 80,5 79 80,33 79,17 3 80,6 81,9 80,7 81 81 82 80,77 81,63 4 80,8 82,5 80,8 80 80,7 80 80,77 80,83 5 79,4 81,7 79,6 84 79,7 86 79,57 83,90 6 79,8 81,6 80,1 87 80,3 88 80,07 85,53 7 78 80,6 78,5 78 78,6 77 78,37 78,53 8 80,1 81,2 80,2 84 80,6 83 80,30 82,73 9 81 81,6 81,5 79 81,6 78 81,37 79,53 10 81,3 81,5 80,8 86 81,6 86 81,23 84,50 11 80,6 83 81 82 81,1 84 80,90 83,00 12 80,7 81 81 85 81,4 84 81,03 83,33 13 79,9 78,3 80 80 80,1 80 80,00 79,43 14 79 78,1 79,1 83 79,1 85 79,07 82,03 15 79,9 81 79,5 81 79,3 82 79,57 81,33 16 80 80,2 80,3 85 80,5 86 80,27 83,73 17 79 79 79,5 81 79,3 81 79,27 80,33 18 78,9 82 79,4 81 79,6 82 79,30 81,67 19 79,3 81,8 79,6 84 80,4 84 79,77 83,27 20 80,5 81 80,9 84 81 85 80,80 83,33 21 79,5 80,6 79,9 81 80 83 79,80 81,53 22 81 80,5 80,6 79 80 79 80,53 79,50 23 81 82 81,2 80 81,8 83 81,33 81,67 24 81,4 80,5 81,5 83 81 81 81,30 81,50 25 80 81,5 81 79 80,8 79 80,60 79,83 Arithmetic mean 80,24 81,70 Standard deviation σ 0,80 1,83 Two standard deviations 2σ 1,60 3,67 Max read range of approx 95% Upper 81,83 85,37 of tags will fall between Lower 78,64 78,03 1st measurement 2nd Measurement 3rd Measurement Mean range ETSI ETSI TR 101 543 V1.1.1 (2011-04) 23 Table A.3: Reading range results for UHF tags Batch 1 Serial No. In (cm) In (cm) In (cm) In (cm) In (cm) In (cm) In (cm) In (cm) 1 3,43 3,48 3,44 3,47 3,46 3,48 3,44 3,48 2 3,22 3,27 3,24 3,27 3,24 3,26 3,23 3,27 3 3,4 3,43 3,41 3,43 3,41 3,42 3,41 3,43 4 3,46 3,49 3,47 3,49 3,47 3,49 3,47 3,49 5 3,44 3,49 3,47 3,49 3,47 3,49 3,46 3,49 6 3,46 3,5 3,46 3,49 3,45 3,49 3,46 3,49 7 3,41 3,47 3,42 3,46 3,43 3,48 3,42 3,47 8 3,45 3,49 3,46 3,49 3,47 3,49 3,46 3,49 9 3,48 3,52 3,48 3,52 3,48 3,51 3,48 3,52 10 3,42 3,46 3,42 3,45 3,42 3,43 3,42 3,45 11 3,44 3,49 3,43 3,48 3,45 3,48 3,44 3,48 12 3,46 3,51 3,47 3,51 3,47 3,5 3,47 3,51 13 3,42 3,5 3,45 3,5 3,46 3,51 3,44 3,50 14 3,43 3,5 3,45 3,5 3,46 3,5 3,45 3,50 15 3,45 3,51 3,46 3,5 3,45 3,49 3,45 3,50 16 3,43 3,49 3,48 3,49 3,45 3,51 3,45 3,50 17 3,44 3,51 3,45 3,52 3,47 3,52 3,45 3,52 18 3,39 3,49 3,45 3,5 3,46 3,52 3,43 3,50 19 3,44 3,49 3,45 3,49 3,46 3,5 3,45 3,49 20 3,23 3,28 3,24 3,27 3,3 3,34 3,26 3,30 21 3,47 3,53 3,47 3,52 3,47 3,5 3,47 3,52 22 2,7 2,8 2,77 2,8 2,77 2,8 2,75 2,80 23 3,47 3,51 3,47 3,5 3,47 3,5 3,47 3,50 24 3,39 3,43 3,23 3,27 3,17 3,18 3,26 3,29 25 3,45 3,49 3,47 3,5 3,47 3,5 3,46 3,50 Batch 2 1 3,47 3,5 3,48 3,51 3,48 3,5 3,48 3,50 2 3,46 3,49 3,47 3,49 3,47 3,49 3,47 3,49 3 3,6 3,62 3,6 3,62 3,61 3,63 3,60 3,62 4 3,48 3,5 3,48 3,5 3,48 3,5 3,48 3,50 5 3,47 3,5 3,47 3,5 3,48 3,5 3,47 3,50 Batch 3 1 3,44 3,48 3,45 3,48 3,44 3,47 3,44 3,48 2 3,45 3,48 3,42 3,46 3,44 3,47 3,44 3,47 3 3,48 3,49 3,48 3,48 3,48 3,49 3,48 3,49 4 3,41 3,43 3,41 3,43 3,41 3,42 3,41 3,43 5 3,43 3,47 3,43 3,46 3,45 3,48 3,44 3,47 Arithmetic mean 3,42 3,45 Standard deviation σ 0,13 0,13 Two standard deviations 2σ 0,27 0,26 Max read range of approx 95% Upper 3,69 3,72 of tags will fall between Lower 3,15 3,19 1st measurement 2nd measurement 3rd Measurement Mean range (cm) ETSI ETSI TR 101 543 V1.1.1 (2011-04) 24 A.2 Results of write tests Table A.4: Results of write tests LF Tests Serial No. Tag Type Point where write fails (cm) 1 Card 3.5 2 Card 4.5 3 Card 4.5 4 Card 6 5 Card 4.5 Arithmetic mean 4.6 Standard Deviation σ 0.89 Two standard deviations 2σ 1.79 Max write range of 95% of tags 6.39 will fall between 2.81 HF Tests Serial No. Tag Type Point where write fails (cm) 26 Proximity 64 27 Proximity 54 28 Proximity 71 29 Proximity 61 30 Proximity 46 Arithmetic mean 59.2 Standard Deviation σ 9.58 Two standard deviations 2σ 19.15 Max write range of 95% of tags 78.35 will fall between 40.05 UHF Tests Serial No. Max read range (m) Point where write fails (m) 1 7.85 7.05 2 8.2 6.9 3 8.5 7.4 4 8.9 8.04 5 9.75 9 Arithmetic mean 8.64 7.678 Standard Deviation σ 0.73 0.86 Two standard deviations 2σ 1.46 1.72 Max write range of 95% of tags 10.10 9.40 will fall between 7.18 5.96 ETSI ETSI TR 101 543 V1.1.1 (2011-04) 25 A.3 Noise floor measurements Table A.5: Noise floor measurements ETSI ETSI TR 101 543 V1.1.1 (2011-04) 26 Annex B: Reports on visits to operational sites B.1 Visit to library at Doetinchem The public library at Doetinchem holds approximately seventy thousand books and a further number of DVDs. All of these items have been fitted with RFID tags operating at 13,56 MHz. The tags have a similar form factor to a credit card and are attached to the inside cover of each book. The data in the tag comprises the following information: • The identification number of the card. • The identification number of the book. • Details concerning any associated annexes. • An identifier denoting the name of the library. All of this information is stored in a central data base within the library. In normal operation authorised customers may take out books on loan and return them without intervention by the library staff. To take out a book it is only necessary to place the selected book on a reading point at the checkout station. See figure B.1. Figure B.1: Library checkout table Having read the tag in the book, the customer is then invited to enter some personal details. This information is logged in the central data base and the customer is authorised to take the book out on loan. The reverse process takes place for the return of the book. However for this activity the central database checks that the book has been returned within the authorised loan period. If the book is overdue, the customer is required to pay a fee. Once the book has been checked in, the customer posts it through a slot into a "returned books" container. An EAS/RFID gate is installed at the exit to the library. See figure B.2. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 27 Figure B.2: EAS/RFID reader at library exit This will alarm in the event that anybody attempts to steal a book or remove one without having correctly completed the check-out procedure. The management of the library were very pleased with the operation of the system and claimed that it had significantly improved their efficiency. B.2 Visit to Metro Future Store The Metro Future Store is used by Metro to test new and innovative marketing concepts. In addition to experimenting with an impressive range of new ideas, it also includes two applications for RFID. The first of these was located at the goods receiving area and the second was used to control the operation of the fresh meat counter. The experts from the STF were shown both installations. In the goods receiving area RFID had been installed at both dock doors and at the interface between the back of store and front of store. Portals containing four antennas were mounted at each reading point. See figure B.3. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 28 Figure B.3: RFID Portal at goods receiving at Metro The antennas were driven by an interrogator that energised each one in turn according to a pre-defined switching sequence. The interrogator was connected to the store's computer system. Operation of each interrogator was triggered by an IR curtain, which was positioned above the portal. The system was used to read tags that were attached to pallets and cartons as they passed through each portal. The system provided greater reliability than manual operation and was less labour intensive. The second application at the fresh meat counter is used to control the transfer of fresh meat. See figure B.4. Figure B.4: Fresh meat counter at Metro Each portion of meat is placed on a polystyrene tray and covered with cellophane. A tag is attached to each tray. An array of antennas is mounted below the meat counter. This allows the meat trays at the counter to be read repeatedly at regular intervals. This means that stocks of meat on display can be kept to an economic minimum and be replenished only when necessary. With the present legislation on the handling of fresh meat, the RFID system ensures compliance with the legal requirements and simplifies the materials handling process. ETSI ETSI TR 101 543 V1.1.1 (2011-04) 29 Annex C: Bibliography Terms of Reference for Specialist Task Force STF 396 (CEN/CENELEC/ETSI) "Response to Phase 1 of EC mandate M/436 (RFID)"SA/ETSI/ENTR/436/2009-02. ETSI EN 300 220-1: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Short Range Devices (SRD); Radio equipment to be used in the 25 MHz to 1 000 MHz frequency range with power levels ranging up to 500 mW; Part 1: Technical characteristics and test methods". ETSI EN 300 330-1: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Short Range Devices (SRD); Radio equipment in the frequency range 9 kHz to 25 MHz and inductive loop systems in the frequency range 9 kHz to 30 MHz; Part 1: Technical characteristics and test methods". ETSI EN 302 208-1: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Radio Frequency Identification Equipment operating in the band 865 MHz to 868 MHz with power levels up to 2 W; Part 1: Technical characteristics and test methods". Directive 1999/5/EC of the European Parliament and of the Council of 9 March 1999 on radio equipment and telecommunications terminal equipment and the mutual recognition of their conformity (R&TTE Directive). ETSI ETSI TR 101 543 V1.1.1 (2011-04) 30 History Document history V1.1.1 April 2011 Publication |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 1 Scope | The present document aims to compare the link level performances of several radio interfaces (HSPA, LTE and mobile WiMAX) in geostationary based mobile satellite systems operating in S band or L band. The present document provides a high level description of the radio interfaces to be compared. It then identifies their key characteristics and defines the propagation channel used for the comparison. Link level performances are compared in terms of required signal to noise ratio ( o b N E ) for a given block error rate (BLER) and data rate. The present document concludes on the respective qualitative benefits and drawbacks of the considered radio interfaces. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 2 References | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the reference document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee their long term validity. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 2.1 Normative references | The following referenced documents are necessary for the application of the present document. Not applicable. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 2.2 Informative references | The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] H. Holma and A. Toskala, "WCDMA for UMTS, Radio Access for Third Generation Mobile Communications", 2nd Edition, John Wiley & Sons, Ltd., 2002. [i.2] ETSI TS 125 201 (V3.4.0): "Universal Mobile Telecommunications System (UMTS); Physical layer - general description (3GPP TS 25.201 version 3.4.0 Release 1999)". [i.3] H. Holma and A. Toskala, "HSDPA/HSUPA for UMTS, High Speed Radio Access for Mobile Communications", John Wiley & Sons, Ltd., 2006. [i.4] ETSI TS 125 201 (V5.3.0): "Universal Mobile Telecommunications System (UMTS); Physical layer - general description (3GPP TS 25.201 version 5.3.0 Release 5)". [i.5] ETSI TS 125 201 (V6.2.0): "Universal Mobile Telecommunications System (UMTS); Physical layer - general description (3GPP TS 25.201 version 6.2.0 Release 6)". [i.6] ETSI TS 125 211 (V6.9.0): "Universal Mobile Telecommunications System (UMTS); Physical channels and mapping of transport channels onto physical channels (FDD) (3GPP TS 25.211 version 6.9.0 Release 6)". [i.7] ETSI TS 136 201 (V8.2.0): "LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Long Term Evolution (LTE) physical layer; General description (3GPP TS 36.201 version 8.2.0 Release 8)". ETSI ETSI TR 101 542 V1.2.1 (2013-07) 7 [i.8] ETSI TS 136 211 (V8.5.0): "LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation (3GPP TS 36.211 version 8.5.0 Release 8)". [i.9] ETSI TS 136 212 (V8.5.0): "LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding (3GPP TS 36.212 version 8.5.0 Release 8)". [i.10] IEEE 802.16-2009: "IEEE Standard for Local and Metropolitan Area Networks - Part 16: Air Interface for Broadband Wireless Access Systems". [i.11] ETSI TR 102 443 (V1.1.1): "Satellite Earth Stations and Systems (SES); Satellite Component of UMTS/IMT-2000; Evaluation of the OFDM as a Satellite Radio Interface". [i.12] R. van Nee and R. Prasad, "OFDM for Wireless Multimedia Communications", Artech House, 2000. [i.13] WiMAX Forum, "Mobile WiMAX - Part I: A Technical Overview and Performance Evaluation", 2006. [i.14] WiMAX Forum, Mobile WiMAX - Part II: "A Comparative Analysis", 2006. [i.15] S. Sesia, I. Toufik and M. Baker,"LTE, the UMTS Long Term Evolution: from Theory to Practice", John Wiley and Sons, 2009. [i.16] Void. [i.17] C. Gessner, "UMTS Long Term Evolution (LTE) Technology Introduction", Application Note 1MA111, Rohde and Schwarz, www2.rohde-schwarz.com/file/1MA111-2E.pdf, Sep. 2008. [i.18] M. Maqbool, M. Coupechoux and P. Godlewski, "Subcarrier permutation types in IEEE 802.16e", www.telecom-paristech.fr/-data/files/docs/id-792-1208254315-271.pdf, Apr. 2008. [i.19] ETSI TR 102 662 (V1.1.1): "Satellite Earth Stations and Systems (SES); Advanced satellite based scenarios and architectures for beyond 3G systems", March 2010. [i.20] 3GPP TR 25.896 (V6.0.0): "Feasibility Study for Enhanced Uplink for UTRA FDD". [i.21] J. Laiho, A. Wacker and T. Novosad, "Radio Network Planning and Optimization for UMTS", John Wiley & Sons, Ltd., 2002. [i.22] ETSI TR 102 058: "Satellite Earth Stations and Systems (SES); Satellite Component of UMTS/IMT-2000; Evaluation of the W-CDMA UTRA FDD as a Satellite Radio Interface". [i.23] ETSI TS 136 104 (V8.2.0): "LTE; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Base Station (BS) radio transmission and reception (3GPP TS 36.104 version 8.2.0 Release 8)". |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 3 Symbols and abbreviations | |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 3.1 Symbols | For the purposes of the present document, the following symbols apply: α Code orthogonality factor o b N E Energy per bit to noise spectral density ratio or c I E Energy per chip to same cell interference density ratio G Geometry factor, which is the same cell interference to other cell interference ratio oc or I I -inf Negative infinite R W Processing gain, which is the chip rate/bit rate TB The useful OFDM symbol duration F Δ Carrier spacing ETSI ETSI TR 101 542 V1.2.1 (2013-07) 8 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 3.2 Abbreviations | For the purpose of the present document, the following abbreviations apply: 3G/ 4G 3rd/ 4th Generation (mobile systems) 3GPP 3rd Generation Partnership Project AMC Adaptive Modulation and Coding AWGN Additive White Gaussian Noise BER Bit Error Rate BLER Block Error Rate BPSK Binary Phase Shift Keying CDMA Code Division Multiple Access CGC Complementary Ground Components CP Cyclic Prefix CPICH Common Pilot Channel CRC Cyclic Redundancy Check CTC Convolutional Turbo Code (Duo-Binary Turbo) DCH Dedicated Channel DFT Discrete Fourier Transform DL Downlink DL+UL Downlink + Uplink DPCCH Dedicated Physical Control Channel DPDCH Dedicated Physical Data Channel DS-CDMA Direct Sequence Code Division Multiple Access E-DCH Enhanced DCH E-DPCCH Enhanced DPCCH E-DPDCH Enhanced DPDCH E-UTRA Evolved Universal Terrestrial Radio Access FDD Frequency Division Duplex FEC Forward Error Control Coding FFSS Frequency band in the spectrum allocated to FSS FFT Fast Fourier Transform FMSS Frequency band in the spectrum allocated to MSS FSS Fixed Satellite Service FUSC Full Usage of the Sub-channels HARQ Hybrid Automatic Repeat Request HD High-speed Downlink HSDPA High Speed Downlink Packet Access HS-DSCH High Speed Downlink Shared Channel HSPA High Speed Packet Access HS-PDSCH High Speed Physical Downlink Shared Channel HS-SCCH High Speed Shared Control Channel HSUPA High Speed Uplink Packet Access IBO Input Back-Off IEEE Institute of Electrical and Electronics Engineers IFFT Inverse Fast Fourier Transform IR Incremental Redundancy LOS Line Of Sight LTE Long Term Evolution (of 3GPP UMTS) MAESTRO Mobile Applications and sErvices based on Satellite and Terrestrial inteRwOrking MIMO Multiple Input Multiple Output MSS Mobile Satellite Services NFFT Number of FFT samples NLOS Non Line of Sight OBO Output Back-Off OFDM Orthogonal Frequency Division Multiplexing OFDMA Orthogonal Frequency Division Multiple Access OVSF Orthogonal Variable Spreading Factor PAPR Peak to Average Power Ratio PCCC Parallel Concatenated Convolutional Code (Binary Turbo) PDSCH Physical Downlink Shared Channel ETSI ETSI TR 101 542 V1.2.1 (2013-07) 9 PhyL Physical Layer PRB Physical Resource Block PUSC Partial Usage of Subcarriers PUSCH Physical Uplink Shared Channel QAM Quadrature Amplitude Modulation QPSK Quadrature Phase Shift Keying RB Resource Block RNC Radio Network Control RV Redundancy Version SC-FDMA Single Carrier Frequency Division Multiple Access SES Satellite Earth Stations and Systems SF Spreading Factor SSPA Solid State Power Amplifier STBC Space Time Block Code Tb Symbol Time (OFDM, without cyclic extension) TDD Time Division Duplex Tg Guard Time or CP duration Ts Symbol Time (OFDM, with cyclic extension) TTI Transmit Time Interval TWTA Travelling Wave Tube Amplifier UE User Equipment UL Uplink UMTS Universal Mobile Telecommunications System UTRA Universal Terrestrial Radio Access VRB Virtual Resource Block WCDMA Wideband Code Division Multiple Access WiMAX Worldwide interoperability for Microwave Access |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 4 Introduction | WCDMA [i.1] to [i.6] is the air-interface for the universal mobile telecommunications system (UMTS) which is a 3G mobile standard specified by the 3GPP. It is based on direct sequence code division multiple access (DS-CDMA) due to its robustness in wideband channels and support for asymmetric data rate applications. Release 4 WCDMA has been enhanced to Release 5 and 6 versions for higher data rate applications. These enhancements, referred to as high speed packet access (HSPA), incorporate advanced features such as higher order modulation, fast link adaption, HARQ and spatial diversity. However, prominent candidates for 4G mobile communications include the 3GPP LTE standard [i.7] to [i.9] and the IEEE mobile WiMAX standard [i.10], both of which are based on orthogonal frequency division multiple access (OFDMA) air-interface, due to its robustness against frequency-selective fading and flexibility of subcarrier allocations. LTE is specified as the long term evolution of UMTS while HSPA can be regarded as its short term evolution. It is observed that all the standards share similarities in the advanced features introduced in HSPA. However, there are fundamental differences in the air-interfaces, frame structures and system/link parameters. Moreover, these standards and their advanced features were specified for terrestrial communications and it would be useful to establish their performance under realistic satellite links (which involve satellite wideband fading channels and power amplifier non- linearity). Therefore, in this study, we compare the link-level performance of HSPA with that of LTE and mobile WiMAX, over satellite links. Figure 1 describes the evolution of the three baseline terrestrial technologies. For performance comparison in the present document, HSPA Release 6, LTE Release 8 and mobile WiMAX Release 1.0 versions are used. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 10 Figure 1: Evolution of HSPA, LTE and Mobile WiMAX 5 Conventional evaluation results on candidate radio interfaces in MSS context In this clause, we recall outcomes of prior feasibility studies on the use of WCDMA and OFDM based radio interface in the context of mobile satellite systems. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 5.1 WCDMA based radio interface | The feasibility study on WCDMA UTRA FDD as a satellite radio interface has been done in TR 102 058 [i.22]. Main study results are summarized as: • MSS systems using WCDMA can complement UMTS network with additional capacity. • Allows technology synergy and interoperability with terrestrial UMTS network. • Enables full frequency reuse in all beams and satellites. • Allows to support broadcast/multicast services over large areas. • Suitable to complement terrestrial UMTS network coverage and services in areas where: - terrestrial systems have not been deployed for business attractiveness reasons; or - terrestrial system requires coverage and/or capacity complement; or - terrestrial system has suffered environmental damages (crisis conditions). In the present document, we will only consider HSPA operation of WCDMA. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 5.2 OFDM based radio interface | A feasibility study on the use of OFDM as a satellite radio interface has been carried out and reported in TR 102 443 [i.11]. Main results are summarized as: • It appears that, notwithstanding the large PAPR, it is possible to efficiently transmit OFDM signals through non-linear satellite links with very small IBO and OBO values. • This surprising result is the fruit of virtuous cross-fertilization between careful predistortion design and powerful forward error correction coding application. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 11 • In frequency flat correlated Rice fading channels and perfect channel estimation, OFDM produces small losses with respect to the HSDPA interface due to only the guard-time insertion. • The link budget study shows that proper service reception can be attained in satellite LOS conditions. In satellite NLOS propagation conditions, proper service reception could not be achieved with this radio interface when considering a handheld terminal, due to a negative link margin. Nevertheless, the use of CGCs can be a viable solution to restore proper service reception in areas where satellite reception is critical. In the present document, we will only consider LTE and Mobile WiMAX version of OFDM. 5.3 Preliminary comparison of OFDM and WCDMA in MSS context Some preliminary comparisons were carried out in TR 102 443 [i.11]: • In multi-path channel conditions (satellite and CGC links), OFDM shows its robustness and, for the considered channel profiles and with ideal channel estimation, OFDM outperforms the radio interfaces based on WCDMA and HSPA. Notably, this is achieved considering the same spectrum occupancy specifications. • Computing the corresponding link budgets for the HSPA case results in low margin for all those cases where the required Rx C/N is higher than for the OFDM case and this is especially true in the NLOS case and when CGCs are considered. 6 Mobile satellite system architecture and service scenario Physical layer performance comparison is achieved in mobile satellite system architecture as below. CGC’s Feeder link Feeder link Access Network 3GPP core network FMSS FFSS FMSS or F F SS F MSS CGC (optional) UE Gateway User link from satellite User link from CGC Figure 2: Mobile satellite system architecture The system may provide either single satellite or multiple satellite constellations and each satellite may provide either single or multi-spot beam coverage. A location area may be either a single spot beam or a group of spot beams for roaming users. UEs are connected to the network via one or several satellites which redirect the radio signal to/from gateways. The system allows for either a centralized gateway or a group of geographically distributed gateways, depending on the operators requirements. The gateway connects the signal to the access network, e.g. Node Bs and RNC. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 12 In a satellite environment, signal transmission suffers from path blocking due to buildings, mountains, etc. In order to ensure coverage continuity in highly shadowed areas, the system can be possibly completed with Complementary Ground Components (CGCs) whose role is to repeat the signal from the satellite to terrestrial coverage in the MSS frequency band and from terrestrial coverage to satellite. CGCs's feeder link is either in MSS or a Fixed Satellite Service (FSS) band. From the system point of view, satellite and CGCs have the same functionality, which is signal repetition. When CGCs are deployed, UEs are subject to communicate with the network: • via the satellite only (areas where CGCs are not deployed or situation with no signal view from CGCs); • via CGCs only (situation where there is no view of the satellite signal); • simultaneously via satellite and CGCs. In this performance comparison, two application scenarios based on the 5 MHz bandwidth are investigated, which are the outdoor rural and outdoor urban environment respectively, with a major difference being the use of repeaters in the urban area to boost the weak satellite signal. A carrier frequency of 2,5 GHz (S-Band) has been used in modelling the Doppler characteristics of the channel. It should be noted that higher-order modulation, AMC, HARQ, STBC/MIMO and power control are not included in this link-level analysis due to the inefficiencies of these techniques in fast-fading satellite links. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 7 High level radio interface description | |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 7.1 Overview | The 3GPP UMTS Release 4 standard is based on wideband code division multiple access (WCDMA) air-interface wherein each user channel is defined by signal spreading with channelization codes or signatures. WCDMA is based on QPSK modulation, 5 MHz carrier bandwidth and FDD duplexing and can support data rates up to 2 Mbps [i.1] and [i.2]. However, it has been enhanced to support higher data rate services with better power/bandwidth efficiencies by using advanced link-level techniques in the subsequent releases (Release 5 and Release 6) of the 3GPP UMTS standard. These enhanced versions are known as the high speed packet access (HSPA) which consists of the high speed downlink packet access (HSDPA) and the high speed uplink packet access (HSUPA) standards respectively [i.3] to [i.6]. The high speed-downlink shared channel (HS-DSCH) is introduced in HSDPA in order to support bursty, asymmetric and high data rate packet applications in user terminals. It supports QPSK/16QAM modulations and uses a basic rate 1/3 parallel concatenated convolutional turbo code (PCCC), with rate-matching to higher or lower code rates via puncturing or repetition. Furthermore, it incorporates important features such as fast link adaptation, HARQ, fixed spreading factor, fast scheduling, multi-code transmission, short TTI of 2 ms, spatial diversity and efficient power utilisation but does not support power control or soft handover. Similarly, an enhanced dedicated channel (E-DCH) is introduced in HSUPA in order to support higher uplink data rates. It makes use of BPSK modulation, orthogonal variable spreading factor (OVSF) codes and a TTI of 10 ms. However, the use of a shorter TTI of 2 ms is (optionally) provided, for better utilization of the short term channel capacity. HSUPA also incorporates features such as link adaptation, HARQ, multi-code transmission and MIMO. In general, it is noted that the more efficient scheduling mechanism in HSPA allows better use of the available spectrum and power budget. On the other hand, the LTE and WiMAX standards [i.7] to [i.11] are based on orthogonal frequency division multiplexing (OFDM) air-interface [i.12], wherein each user resource is defined by time-frequency subcarrier allocations. Both standards support scalable bandwidths (e.g. 1,25 MHz, 5 MHz and above), FDD/TDD duplexing and are designed to provide high data rate services with improved power/bandwidth efficiencies. Similar to the HSPA standards, they also incorporate advanced link-level techniques such as AMC, HARQ, short TTI, and MIMO. It should be noted that LTE is a 3GPP standard which is structured as the long term evolution of UMTS while HSPA can be considered as its short-term evolution. Similar to HSPA, the LTE standard uses a basic rate 1/3 parallel concatenated convolutional turbo code (PCCC) with rate-matching whereas WiMAX specifies a variety of FEC codes, including the duo-binary convolutional turbo code (CTC). The LTE and WiMAX standards share a lot of similarities due to their common use of OFDMA. However, there are differences in frame structure, system parameters and subcarrier multiplexing. Furthermore, LTE uses a DFT-spread OFDMA in its uplink in contrast to WiMAX which uses direct OFDMA in both uplink and downlink. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 13 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 7.2 HSPA frame structure | HSDPA has a 10 ms radio frame which is consistent with the Release 4 WCDMA standard, wherein each radio frame consists of 15 slots and each slot is made up of 2 560 chips, resulting in a chip rate of 3,84 MChips/s. However, as shown in figure 3, it uses a shorter TTI equivalent to one subframe of 2 ms duration (i.e. 3 slots) in contrast to the longer TTIs (10 ms, 20 ms, etc.) supported in Release 4 WCDMA. This enables it to achieve fast link adaptation, fast scheduling and low latency. HSDPA uses a fixed spreading factor of 16 and the number of coded bits per TTI is only dependent on the modulation used. For QPSK, this is equal to 960 bits per channelization code while the number of coded bits becomes doubled for 16-QAM as shown in table 1. The transport channel for HSDPA is the High Speed Downlink Shared Channel (HS-DSCH) which is carried on the High Speed Physical Downlink Shared Channel (HS-PDSCH). An HS-PDSCH corresponds to one channelization code and multi-code transmission is supported, which translates to one user equipment (UE) being assigned multiple channelization codes in the same TTI, depending on its capability. The High Speed Shared Control Channel (HS-SCCH) carries relevant downlink control information associated with the HS-DSCH. Table 1: HS-PDSCH slot formats [i.6] Slot format #i Channel Bit Rate (kbps) Channel Symbol Rate (ksps) SF Bits/ HS-DSCH subframe Bits/ Slot Ndata 0(QPSK) 480 240 16 960 320 320 1(16QAM) 960 240 16 1 920 640 640 Slot #0 Slot#1 Slot #2 T slot = 2560 chips, M*10*2 k bits (k=4) Data N data 1 bits 1 subframe: T f = 2 ms Figure 3: HSDPA Frame Structure [i.6] Data, Ndata bits Slot #1 Slot #14 Slot #2 Slot #i Slot #0 Tslot = 2560 chips, Ndata = 10*2k bits (k=0…7) Tslot = 2560 chips 1 subframe = 2 ms 1 radio frame, Tf = 10 ms E-DPDCH E-DPDCH E-DPCCH 10 bits Figure 4: HSUPA Frame Structure [i.6] ETSI ETSI TR 101 542 V1.2.1 (2013-07) 14 HSUPA also has a radio frame structure similar to that of HSDPA and Release 4 WCDMA, wherein each radio frame consists of 15 slots and each slot is made up of 2 560 chips as shown in figure 2. However, it uses a TTI of 10 ms duration with an optional support for 2 ms [i.3] and [i.6]. HSUPA uses BPSK modulation and OVSF channelization codes (with spreading factor ranging from 256 down to 2). Consequently, the number of coded bits per TTI varies with the spreading factor as shown in table 2. The transport channel for HSUPA is the Enhanced Dedicated Channel (E-DCH) which is carried on the Enhanced Dedicated Physical Data Channel (E-DPDCH). This channel co-exists with the Release 99 DCH and there may be zero, one, or several E-DPDCH on each radio link. The Enhanced Dedicated Physical Control Channel (E-DPCCH) is used to transmit control information associated with the E-DCH. There is only one E-DPCCH on each radio link, transmitted simultaneously with the E-DPDCH and always accompanied by the Release 99 DPCCH (which is used for channel estimation). Table 2: E-DPDCH slot formats [i.6] Slot Format #i Channel Bit Rate (kbps) SF Bits/ Frame Bits/ Subframe Bits/Slot Ndata 0 15 256 150 30 10 1 30 128 300 60 20 2 60 64 600 120 40 3 120 32 1 200 240 80 4 240 16 2 400 480 160 5 480 8 4 800 960 320 6 960 4 9 600 1 920 640 7 1 920 2 19 200 3 840 1 280 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 7.3 LTE/WiMAX frame structure | In the LTE standard, the basic resource for either UL or DL transmission is a resource block (RB), which is defined as 12 tones x 6 OFDM symbols for the extended CP configuration and 12 tones x 7 OFDM symbols for the normal CP configuration. The normal CP configuration is intended for environments with low multipath caracteristics. The extended CP configuration is intended for environments with high multipath characteristics. Each RB includes both pilot and data subcarriers. Table 3 : Number of Resource Block for given Channel bandwidth Channel bandwidth [Mhz] 1,4 3 5 10 15 20 Number of Resource Block per 0,5 ms slot 6 15 25 50 75 100 Number of Resource Block per 10 ms frame 120 300 500 1 000 1 500 2 000 A TTI in LTE consists of two adjacent resource blocks in time domain. The LTE TTI is equivalent to one subframe, with duration of 1 ms (equivalent to two time slots) for both physical uplink and downlink shared channels (PUSCH and PDSCH) and one radio frame in LTE has a duration of 10 ms similar to WCDMA and HSPA. Figure 5: Frame structure type 1 (FDD) ETSI ETSI TR 101 542 V1.2.1 (2013-07) 15 Figure 6: LTE downlink Resource Block (extended CP); 0,5 ms duration – 180 Khz Figure 7: LTE uplink Resource Block (extended CP); 0,5 ms duration – 180 Khz WiMax supports TDD and FDD mode. The frame duration is variable (2/2,5/4/5/8/10/12,5/20 ms). The number of subcarriers depends on the size of the FFT (128, 512, 1 024, 2 048). Figure 8 shows an example of TDD frame, with the different burst in time and frequency. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 16 Figure 8: WiMAX frame structure example (TDD) Figure 9 shows an example of FDD frame. The frame is split in two groups, each terminal is affected to one of these groups: Figure 9: WiMAX frame structure example (FDD) The basic resource in WiMAX is a subchannel of 48 data subcarriers. There are two modes for the DL: • FUSC (Fully Used Subcarriers): a subchannel is composed of 48 data subcarriers over one symbol time. • PUSC (Partially Used Subcarriers): a subchannel is composed of 2 clusters over two symbol time. Each cluster is composed of 12 data carriers and 2 pilot carriers. In the UL there is only the PUSC mode: the subchannel is composed of six tiles. Each tile is composed of 4 carriers over three symbol time. A tile contains 4 pilots and 8 data carriers. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 17 Although a TTI is not explicitly specified in the present document, the WiMAX forum [i.13], [i.14] has configured a radio frame structure of 5 ms duration for the TDD mode but has yet to specify one for the FDD mode. Therefore, in keeping with the generic structure of the basic resource for both uplink and downlink, we envisage a TTI consisting of 6 OFDM symbols or its multiples. For the purpose of consistency with LTE, we choose a TTI of 12 OFDM symbols for WiMAX FDD, which is equivalent to 6 clusters in downlink PUSC and 4 tiles in uplink PUSC, as shown in figures 5 and 6. This results in an WiMAX TTI duration of 1,37 ms for the 25 % CP configuration. 2 4 6 8 10 12 2 4 6 8 10 12 14 OFDM Symbols Subcarriers NOTE: Blue: pilot subcarriers. White: data subcarriers. Figure 10: WiMAX downlink-PUSC TTI (6 clusters, 25 % CP); 1,37 ms duration NOTE: Blue: pilot subcarriers. White: data subcarriers. Figure 11: WiMAX uplink-PUSC TTI (4 tiles, 25 % CP); 1,37 ms duration 8 Radio interface parameters for performance comparison |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 8.1 HSPA parameters | The HSPA system design can be very complicated due to several factors that affect its link-level performance. This is as a result of the fact that the whole bandwidth is accessed at all times by all users, wherein multiple access is achieved through the use of channelization codes which spread each user's signal into chips using a unique signature. Therefore, users are separated in the code domain and a uniform number of chips are transmitted per user. In HSPA, 38 400 chips are transmitted in each 10 ms radio frame, 7 680 chips per 2 ms subframe and 2 560 chips per slot, resulting in a chip rate of 3,84 Mchips/s. Table 4 shows important parameters that determine the link performance in HSPA. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 18 Table 4: HSPA system/link parameters Info. Bits Total (Payload) 320 3 200 3 200 4 800 4 800 No. of Ch. Codes 1 10 10 15 15 Info. Bits / Ch. Code 320 320 320 320 320 FEC Rate 0,333 0,333 0,333 0,333 0,333 FEC Coded Bits / Ch. Code 960 960 960 960 960 FEC Coded Bits Total 960 9 600 9 600 14 400 14 400 Modulation Index 2 2 2 2 2 TTI Duration, [s] 0,002 0,002 0,002 0,002 0,002 No. of Chips / TTI 7 680 7 680 7 680 7 680 7 680 Spreading Factor 16 16 16 16 16 Max. Tx. Symbols / TTI 480 480 480 480 480 Chip Rate, [Chips/s] 3 840 000 3 840 000 3 840 000 3 840 000 3 840 000 Data Rate / Ch. Code, [Bits/s] 160 000 160 000 160 000 160 000 160 000 Data Rate Total, [Bits/s] 160 000 1 600 000 1 600 000 2 400 000 2 400 000 Processing Gain 24 2,4 2,4 1,6 1,6 Orthogonality Factor 1 1 0,5 1 0,5 Ec/Ior, [dB] -1 -1 -1 -1 -1 Ior/Ioc, [dB] 0 10 20 10 20 Eb/N0, [dB] 12,80 12,80 5,73 11,04 3,.97 Load Factor 0,44 0,09 0,31 0,09 0,31 Noise Rise, [dB] 2,54 0,40 1,62 0,40 1,62 In HSPA, the 0 N Eb value is determined by parameters such as the processing gain, or c I E , geometry factor and code orthogonality factor, as shown as below [i.3]. WCDMA uses orthogonal codes in the downlink to separate simultaneously transmitted user signals. However, delay spread in a wideband channel causes the mobile receiver to see part of the transmitted signal as multiple access interference. Consequently, the code orthogonality factor has a value of 1 for a single-tap downlink channel, whereas it varies between 0,4 and 0,9 for a wideband downlink channel [i.3]. ( )( ) ( ) ( ) G I E R W N E or c o b 1 1 + − = α where, 0 N Eb : Energy-per-bit to noise-interference-density R W : Processing gain, which is the chip rate/bit rate or c I E : Energy-per-chip to same-cell-interference-density α : Code orthogonality factor G : Geometry factor, which is the same-cell-interference to other cells-interference ratio oc or I I . Table 1 shows that multi-code transmission increases the data rate while reducing the processing gain and achievable 0 N Eb . Also, increasing or c I E and/or G has a positive effect on the achievable 0 N Eb . However, the effect of a good geometry factor is dampened by loss of orthogonality in the multipath downlink channel as it results in a non- linear increase in interference. Another factor to note is that the noise rise over thermal (which relates to the interference margin in HSPA link budgets and is directly determined from the load factor) is most strongly affected by the geometry factor as explained in [i.3]. It can be easily deduced from the discussions above that the capacity and coverage of the HSPA link is interference limited. However, a frequency re-use of 1, interference control mechanisms and user demand for asymmetric data rates provide great flexibilities in HSPA to achieve higher capacities, wherein compromise can be made between capacity and coverage per user. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 19 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 8.2 LTE/ WiMAX parameters | As discussed earlier, the LTE and WiMAX standards are based on OFDM/OFDMA multiplexing which is efficiently implemented in digital receivers using the Fast Fourier Transform (FFT) algorithm. Both use fixed subcarrier spacing for their OFDM signals and therefore support different FFT sizes for different bandwidths. In addition to the OFDM signal design requirements, the subcarrier spacing in LTE was carefully chosen by the 3GPP as F Δ = 15 KHz, in order to ensure a signal sampling rate which is an integer multiple of the WCDMA chip rate [i.15]. Consequently, an FFT size of 512 (corresponding to the 5 MHz bandwidth) results in an OFDM signal sampling rate of 7,68 MHz which is double the WCDMA chip rate. Table 5 summarizes the OFDM parameters applicable to the extended CP configuration of LTE and the 25 % CP configuration in WiMAX, wherein TB is the useful OFDM symbol duration ( F TB Δ =1 ), TG is the guard interval or CP duration and TS is total OFDM symbol duration. Table 5: LTE/WiMAX OFDM parameters Standard ∆F [KHz] TB [μs] TG [μs] TS [μs] TTI [symbols] TTI [ms] LTE extended CP 15 66,67 16,67 83,33 12 (including 2 pilots in uplink) 1,00 LTE normal CP 15 66,67 5,21 (first) 4,69 (other) 71,88 (first) 71,36 (other) 14 (including 2 pilots in uplink) 1,00 WiMAX 10,94 91,41 22,85 114,26 12 1,37 The time-frequency parameters shown in tables 6 and 7 for downlink and uplink configurations respectively show that LTE is able to achieve higher data rates than WiMAX for a fixed bandwidth and the gap widens in the uplink. This is due to the higher density of pilots used in the WiMAX standard in contrast to LTE. However a higher density of pilots should enhance channel estimation accuracy, thereby compensating capacity loss with improved link performance. Table 7 shows important parameters for OFDM link analysis, where it is shown that the achievable data rate is dependent on the TTI data resource (i.e. excluding pilot tones), modulation, FEC code rate and TTI duration. In contrast to HSPA, the energy-per-bit in OFDM is directly determined since users are multiplexed in the time-frequency domain and not in the interference-limited code domain. Table 6: 5 MHz DL time-frequency parameters Standard NFFT Nused CP Length Basic Data Resource TTI Data Resource Max. QPSK Data Rate [Mbits/s] LTE extended CP 512 300 512 (see note 1) 68 (sub carriers per RB) 3 400 6,80 LTE normal CP 512 300 160 (first) (Note 1) 144 (rest) (see note 1) 80 (sub-carriers per RB) (see note 2) 4 000 8,00 WiMAX 512 420 128 48 4 320 6,31 NOTE 1: For LTE, the CP duration is expressed as a multiple of a fixed sampling time Ts=1/(15000*2048). Thus 512 Ts = 16,67µs, 160 Ts = 5,2 µs, 144 Ts = 4,69 µs NOTE 2: For LTE downlink, a Resource Block contains 6 OFDM data symbols (extended CP mode ) or 7 OFDM data symbols (normal CP mode). Each of these OFDM data symbols is composed of 12 sub-carriers which are modulated in QPSK mode (resp. BPSK, 16QAM, 64 QAM). In each Resource Block, 4 sub- carriers are reserved for physical layer procedures. A TTI is one ms (2 slots) ETSI ETSI TR 101 542 V1.2.1 (2013-07) 20 Table 7: 5 MHz UL time-frequency parameters Standard NFFT Nused CP Length Basic Data Resource TTI Data Resource Max. QPSK Raw Data Rate [Mbits/s] LTE extended CP 512 300 512 (see note 1) 60 (QPSK symbols per RB) (see note 2) 3 000 (QPSK symbols per TTI) 6,00 LTE normal CP 512 300 160 (first) (see note 1) 144 (rest) (see note 1) 72 (QPSK symbols per RB) (see note 2) 3 600 (QPSK symbols per TTI) 7,20 WiMAX 512 408 128 48 3 264 4,76 NOTE 1: For LTE, the CP duration is expressed as a multiple of a fixed sampling time Ts=1/(15 000*2 048). Thus 512 Ts = 16,67µS, 160 Ts = 5,2 µs, 144 Ts = 4,69 µS. NOTE 2: For LTE uplink, a Resource Block contains 5 SC-FDMA data symbols (extended CP mode ) or 6 SC-FDMA data symbols (normal CP mode). Each of these SC-FDMA data symbols is composed of 12 QPSK (resp. BPSK, 16QAM, 64QAM) modulated symbols. Table 8: LTE/WiMAX system/link parameters Standard LTE DL extended CP LTE DL normal CP WiMAX DL LTE UL extended CP LTE UL normal CP WiMAX UL Info. Bits (Payload) 2 304 2 688 2 880 2 016 2 432 1 920 FEC Rate 0,338 0,336 0,333 0,336 0,338 0,333 FEC Coded Bits Total 6 800 8 000 8 640 6 000 7 200 5 760 Mod. Index 2 2 2 2 2 2 Modulated Symbols 3 400 4 000 4 320 3 000 3 600 2 880 TTI duration, [s] 0,001 0,001 0,00137 0,001 0,001 0,00137 TTI Data Resource 3 400 4 000 4 320 3 000 3 600 3 264 Sampling Rate, Sample [s/s] 7 680 000 7 680 000 5 601 280 7 680 000 7 680 000 5 601 280 Data Rate Total, [Bits/s] 2 304 000 2 688 000 2 102 .190 2 016 000 2 432 000 1 401 460 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 9 Hypothesis for performance comparison | |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 9.1 Channel model | The wideband fading channel models used in this link-level analysis are based on the MAESTRO project measurements [i.19]. In particular, we select two power-delay profiles which provide a close match to the outdoor rural and outdoor urban scenarios. These are the MAESTRO channel 1 and 5 power-delay profiles which are shown in tables 9 and 10 respectively. The multipath fading channel is implemented based on the Jake's model and each channel tap undergoes independent time-variant fading (Rician or Rayleigh) according to the specified K-factor and mobile speed. Table 9: MAESTRO channel 1: Satellite line-of-sight with many rays (outdoor rural) Power [dBm] -91,9 -106,3 -110,1 -112,5 -110,2 -112,5 -112,5 Delay [ns] 0 195,3 260,4 846,3 1 171,9 1 953,1 2 734,3 K-factor [dB] 10 -inf -inf -inf -inf -inf -inf Table 10: MAESTRO channel 5: Satellite + 3 Intermediate Module Repeaters (outdoor urban) Power [dBm] -91,8 -67,8 -80,7 -67,5 -72,8 -69,6 -73,1 -74,8 -78,4 -81,6 Delay [ns] 0 1 692,7 1 757,8 2 278,6 2 343,7 2 408,8 3 190,0 8 203,0 8 268,1 8 788,9 K-factor [dB] 7 -inf -inf -inf -inf -inf -inf -inf -inf -inf ETSI ETSI TR 101 542 V1.2.1 (2013-07) 21 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 9.2 TWTA model | −40 −35 −30 −25 −20 −15 −10 −5 0 5 10 −35 −30 −25 −20 −15 −10 −5 0 Input Back−Off (dB) Output Back−Off (dB) Figure 12: TWTA amplitude-to-amplitude response −40 −35 −30 −25 −20 −15 −10 −5 0 5 10 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Input Back−Off (dB) Phase Offset (radians) Figure 13: TWTA amplitude-to-phase response The TWTA model implemented in the simulators is based on typical S-Band power amplifier specifications which are defined in terms of input back-off, output back-off and phase offset. Its amplitude-to-amplitude response is illustrated in figure 12, wherein an input back-off of 0 dB indicates the saturation point. As is expected, the amplifier becomes increasingly non-linear when it is operated close to saturation and it can be seen that the output power reduces when it is operated beyond the saturation point. However, satellite applications are usually power constrained and therefore designed to make the most use of power available from the TWTA. Figure 13 shows the amplitude-to-phase response of the TWTA wherein it can be seen that an increasing phase offset is introduced into the amplified signal as the TWTA approaches saturation. The power amplifier non-linearity takes on an increased relevance in LTE/WiMAX and HSPA due to the inherently high PAPR of OFDM and multi-code CDMA transmission respectively. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 22 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 9.3 Simulation parameters | It should be noted that higher-order modulation, AMC, HARQ, STBC/MIMO and power control are not included in this link-level analysis due to the inefficiencies of these techniques in fast-fading satellite links. Rate 1/3 FEC coding is chosen as default in this performance comparisons, except otherwise stated. The CP duration for LTE/WiMAX is set as 25 % of the useful symbol duration, in order to ensure that it accommodates the delay spread of the selected MAESTRO channels. It is assumed that the link degradation caused by the satellite TWTA is much more significant than that of the user terminal SSPA. Consequently, only the satellite TWTA is taken into account for the link-level analysis. Simulations are performed for two modes of satellite TWTA operation in order to investigate in a linear region with IBO = 30 dB whilst in the second mode, the TWTA is operated in the saturation region with IBO = 0 dB. For the downlink comparison, block sizes are chosen for each standard such as to achieve comparable data rates (approaching the maximum possible) for rate 1/3 coding subject to the constraints of block sizes allowed by the code interleavers, data subcarriers available and the practical number of channelization codes. This approach is important as the standards under consideration have different system parameters, including TTI duration as discussed in clause 7. Therefore, we compare link performance within the context of user data rate. The uplink comparison takes on a similar approach but some flexibility is introduced due to wide gap in TTI duration between HSPA and LTE/WiMAX. The HSPA simulator implements only the 10 ms TTI (the 2 ms TTI is optional) and thus will benefit more from channel interleaving as compared to the shorter TTIs of LTE and WiMAX. Therefore, in one set of uplink simulations, the LTE and WiMAX standards are modified to ~10 ms TTI (as shown in brackets in table 12) in order to achieve similar interleaving gain, wherein HSPA is investigated using the practical evaluation scenario of one channelization code with a spreading factor of 4 [i.20],[i.3]. In this scenario of a larger TTI, the block size of LTE is matched with that of HSPA (as shown in brackets in table 11) while that of WiMAX is maintained due to the constraint of block sizes allowed. Another set of uplink simulations compares the unmodified LTE and WiMAX standards for data rates approaching the maximum possible for the code rate 1/3. Tables 10 and 11 summarise key parameters used in the computer simulations. Table 11: Downlink simulation parameters Standard HSPA LTE WiMAX Bandwidth [MHz] 5 5 5 TTI [ms] 2 1 1,37 Block Size 4 800 (3 200) 2 304 2 880 Data Rate [Mbps] 2,4 (1,6) 2,3 2,1 FEC Turbo (PCCC) Turbo (PCCC) Turbo (CTC) FEC Rate 0,333 0,333 0,333 Modulation QPSK QPSK QPSK Channel Profile MAESTRO MAESTRO MAESTRO Channel Type Ch. 1, Ch. 5 Ch. 1, Ch. 5 Ch. 1, Ch. 5 Mobile Speed [km/h] 120 120 120 NOTE: An additional block size as shown in brackets in investigated for HSPA due to the o b N E saturation experienced by the default choice. Table 12: Uplink simulation parameters Standard HSPA LTE WiMAX Bandwidth [MHz] 5 5 5 TTI [ms] 10 (10), 1 (9,59), 1,.37 Block Size 2 560 (2 560), 1 920 1 920 Data Rate [Mbps] 0,256 (0,256), 1,92 (0,2), 1,4 FEC Turbo (PCCC) Turbo (PCCC) Turbo (CTC) FEC Rate 0,267 0,333 0,333 Modulation BPSK QPSK QPSK Channel Profile MAESTRO MAESTRO MAESTRO Channel Type Ch. 1 Ch. 1 Ch. 1 Mobile Speed [km/h] 120 120 120 ETSI ETSI TR 101 542 V1.2.1 (2013-07) 23 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 10 Performance comparison results | HSPA link performance has been compared with LTE and WiMAX based on the 5 MHz carrier bandwidth, in satellite wideband fading channels and in the presence of power amplifier non-linearity. Extensive computer simulations were run for high data rate transmissions (with FEC code rate 1/3) and results presented in terms of block error rate (BLER). In the downlink, '2,4 Mbps and 1,6 Mbps' were tested for HSPA, 2,3 Mbps for LTE and 2,1 Mbps for WiMAX. For uplink transmissions, 0,256 Mbps is tested for HSPA, '0,256 Mbps and 1,92 Mbps' for LTE and '0,2 Mbps and 1,4 Mbps' for WiMAX. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 10.1 Link performance aspect | Simulation results show that for a target BLER, HSPA requires an o b N E comparable to that of LTE/WiMAX in satellite-only wideband fading channels (such as the MAESTRO channel 1 representing the outdoor rural profile) due to their moderate delay spread. However, HSDPA (HSPA downlink) requires a significantly lower o b N E than LTE/WiMAX in satellite channels which incorporate the use of terrestrial repeaters to boost the weak satellite signal (such as the MAESTRO channel 5 representing the outdoor urban profile). This is due to a combination of multipath diversity gain (achieved via Rake reception of many channel taps) and multiple access interference resulting from the low code orthogonality factor of such channels which have a large delay spread. Nevertheless, it is noted that a significantly higher geometry factor is needed to achieve the required o b N E in these channels, which translates into reduced coverage. Furthermore, implementing a large number of Rake fingers is not practical in consumer-grade terminals. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 10.2 User data rate aspect | The significant loss of code orthogonality in wideband channels with large delay spread (such as MAESTRO channel 5) constitutes a severely limiting factor for very high data rate transmissions in HSDPA as the required o b N E for good link quality cannot be achieved despite increasing the geometry factor to very high values. This is reflected in the 2,4 Mbps HSDPA transmission as o b N E saturation occurs at ~4,5 dB such that a BLER = 10-3 is never achieved. A frequency re-use of 1 means that good link quality cannot be achieved for high data rate transmissions at edge of cell areas due to increased interference. This is reflected in the high geometry factors required to achieve good link quality for both MAESTRO channel 1 and 5. On the other hand, LTE and WiMAX achieve a robust link-level performance in terms of insensitivity to the afore-mentioned limiting factors of HSPA. Also, by making use of fractional frequency re- use (which is enabled by the flexibility of subcarrier allocation in OFDMA), it is expected that interference will be a less significant issue with LTE/WiMAX, thereby helping to achieve wider coverage for high data rate applications. |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 10.3 Non-linearity effect | All the standards experience comparable degradation in link performance due to the amplifier non-linearity. In HSDPA, this results from the PAPR arising from multi-code transmission while it is due to the PAPR arsing from OFDM IFFT processing in LTE/WiMAX. LTE shows less sensitivity to amplifier non-linearity in the uplink due to its use of SC- FDMA (DFT-spread-OFDM) in contrast to direct OFDMA used in WiMAX UL PUSC. In comparison, a single-code single-user transmission in HSUPA means that the amplifier non-linearity has very little impact on link performance. However, the use of multi-code transmission in HSUPA will increase the PAPR and degrade performance in similar fashion to HSDPA. It has been shown in previous work [i.15], [i.18] that the effects of TWTA non-linearity can be mitigated through a combined used of back-off and digital pre-distortion. Based on the link-level results, it can be concluded that LTE and WiMAX achieve a more robust link performance than HSPA over satellite links. However, a key issue in the link performance of all the standards is the absence of significant time diversity within one TTI duration. This leads to a potential performance loss of ~5 dB or more as reflected in the uplink results, due to the absence of time interleaving gain. Terrestrial systems can compensate for this problem by using techniques such as HARQ but this will be more challenging in satellite links which have a longer round trip time. Since satellite systems tend to be power-limited and the advantage of a low-latency TTI is prevented by the satellite link delay, there is need to develop robust satellite-specific link layer mechanisms to solve this issue in order to enable the deployment of LTE/WiMAX over satellite links with maximum commonality. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 24 |
83343f810db97cb672cbc39bfe048d6e | 101 542 | 11 Conclusion | Link-level performance comparison between HSPA, LTE and WiMAX over satellite links is summarized as follows: • HSDPA (HSPA downlink) requires an Eb/No comparable to that of LTE/WiMAX in satellite-only wideband fading channels (such as the MAESTRO channel 1) due to their moderate delay spread. • HSDPA requires a significantly lower Eb/No than LTE/WiMAX in satellite channels which incorporate the use of terrestrial repeaters to boost the weak satellite signal (such as the MAESTRO channel 5) due to a combination of multipath diversity gain (Rake reception) and multiple access interference (low code orthogonality factor of channels with large delay spread). - Nevertheless, a significantly higher geometry factor is needed to achieve the required Eb/No in these channels, which translates into reduced coverage. Furthermore, implementing a large number of Rake fingers is not practical in consumer-grade terminals. • The significant loss of code orthogonality in wideband channels with large delay spread (such as MAESTRO channel 5) constitutes a severely limiting factor for very high data rate transmissions in HSDPA. • All the radio interfaces experience comparable degradation in link performance due to the amplifier non-linearity. - HSPA: Due to PAPR arising from multi-code transmission. - LTE/WiMAX: Due to the PAPR arsing from OFDM IFFT processing. - LTE shows less sensitivity to amplifier non-linearity in the uplink due to its use of SC-FDMA (DFT-spread-OFDM) in contrast to direct OFDMA used in WiMAX UL. Based on the link-level results, it can be concluded that LTE and WiMAX achieve a more robust link performance than HSPA over satellite links. However, a key issue in the link performance of all the radio interfaces is the absence of significant time diversity within one TTI duration. This leads to a potential performance loss of ~5 dB as reflected in the uplink results, due to the absence of time interleaving gain. Finally, table 13 highlights the benefits of each terrestrial radio interface respect to link-level performance. The following scale of characteristics is defined for use in table 13: 1) For the link performance, 'robust' means that the Eb/No needed for a target BER can be achieved while 'limited' means that the link experiences Eb/No saturation due to air interface constraints. 2) For the receiver complexity, 'high' means that a large number of receiver taps are needed for optimum channel equalization while 'low' means that only single tap equalization is required for optimum performance. 3) For the user data rate, 'limited' means that the achievable link data rate is below the maximum possible due to air interface constraints while 'robust' means that the maximum possible data rate is not constrained by the air interface. 4) For the link degradation due to amplifier non-linearity, 'high' means that the link experiences more than 1,5 dB degradation while 'low' means that the link experiences lower than 1,5 dB degradation. Table 13: Summary of performance comparison Air interface HSPA LTE WiMAX Link performance in satellite-only channel Robust Robust Robust Link performance in satellite+CGC channel Limited Robust Robust Receiver complexity in satellite+CGC channel High Low Low User data rate in satellite+CGC channel Limited Robust Robust Link degradation due to amplifier non-linearity High (DL+UL) High (DL), Low (UL) High (DL+UL) ETSI ETSI TR 101 542 V1.2.1 (2013-07) 25 Annex A: Detailed description of simulation A.1 Overview The link-level performance comparison between HSPA and LTE/WiMAX air interfaces is based on existing simulators developed at the University of Surrey. The HSPA simulator is a C++ link-level simulator of 3GPP UMTS Release 99 with enhanced functionality for Release 5 and 6 (HSDPA and HSUPA) [i.1] to [i.6]. It is extended to include satellite wideband fading channels and TWTA non-linearity. The HSPA simulator has been validated in comparison with results obtained from the telecommunications industry [i.15]. On the other hand, the more recently developed LTE/WiMAX simulators are based on the Matlab/C platform and implement the physical layer specifications of LTE [i.7] to [i.9] and WiMAX [i.10] and [i.11]. The performances of these simulators were validated. A.2 HSPA Simulator The HSPA simulator architectures are shown in figures A.1 and A.2 for HSDPA and HSUPA respectively. Redundancy Version (RV) Setting ACK/NACK CQI Mux Chain HS-DSCH HS-SCCH CPICH OCNS DeMux Chain Rx Tx Payload Channel CRC Check Block DeSegmt Ch DeCoding PhyL HARQ PhyCh DeSegmt HS-DSCH DeInterleaving PhyCh De Mapping Code #1 Code #2 Code #N CRC Attach Block Segmt Ch Coding PhyL HARQ PhyCh Segmt HS-DSCH Interleaving PhyCh Mapping Code #1 Code #2 Code #N MoD Spreading Scrambling Channel Est Rake Fn Soft DeMoD DeSpreading DeScrambling Combining Bit Separation 1st Rate Matching IR Buffer 2nd Rate Matching Bit Combining 1st DeRate Matching ReTx Combining 2nd DeRate Matching HSDPA Simulation Model Time Delay Redundancy Version (RV) Setting ACK/NACK CQI Mux Chain HS-DSCH HS-SCCH CPICH OCNS DeMux Chain Rx Tx Payload Channel CRC Check Block DeSegmt Ch DeCoding PhyL HARQ PhyCh DeSegmt HS-DSCH DeInterleaving PhyCh De Mapping Code #1 Code #2 Code #N CRC Attach Block Segmt Ch Coding PhyL HARQ PhyCh Segmt HS-DSCH Interleaving PhyCh Mapping Code #1 Code #2 Code #N MoD Spreading Scrambling Channel Est Rake Fn Soft DeMoD DeSpreading DeScrambling Combining Bit Separation 1st Rate Matching IR Buffer 2nd Rate Matching Bit Combining 1st DeRate Matching ReTx Combining 2nd DeRate Matching HSDPA Simulation Model Time Delay ACK/NACK CQI Mux Chain HS-DSCH HS-SCCH CPICH OCNS DeMux Chain Rx Tx Payload Channel CRC Check Block DeSegmt Ch DeCoding PhyL HARQ PhyCh DeSegmt HS-DSCH DeInterleaving PhyCh De Mapping Code #1 Code #2 Code #N CRC Attach Block Segmt Ch Coding PhyL HARQ PhyCh Segmt HS-DSCH Interleaving PhyCh Mapping Code #1 Code #2 Code #N MoD Spreading Scrambling MoD Spreading Scrambling Channel Est Rake Fn Channel Est Rake Fn Soft DeMoD DeSpreading DeScrambling Combining Bit Separation 1st Rate Matching IR Buffer 2nd Rate Matching Bit Combining 1st DeRate Matching ReTx Combining 2nd DeRate Matching HSDPA Simulation Model Time Delay Time Delay Figure A.1: HSDPA Simulation Model ETSI ETSI TR 101 542 V1.2.1 (2013-07) 26 Figure A.2: HSUPA Simulation Model These include modules such as the multiplexing chain (CRC attachment, transport block segmentation/concatenation, channel coding, physical layer HARQ, physical channel segmentation, interleaving, physical channel mapping), modulation mapping, spreading and scrambling operations at the transmitter side. The signal then passes through the radio channel and the reverse operations are performed at the receiver in the presence of interference as well as background noise (both modelled as additive white Gaussian noise). The receiver implements channel estimation (Ideal or through CPICH/DPCCH), Rake reception (with the option of combining 'm' best out of 'n' paths where n > m), diversity combining and turbo decoding with max-log map algorithm. The PhyL HARQ functionality consists of two rate matching stages and a virtual buffer. It is controlled by redundancy version (RV) parameters which determine whether incremental redundancy (IR), chase combining or combination of both modes is active in a certain period of time. A.3 LTE/WiMAX simulator The block diagrams of figure A.3 and A.4 show the modules incorporated into the link-level simulators for LTE and WiMAX respectively. In general, the transmitted signal consists of a block of random information bits which are generated according to the block sizes specified by each standard. These bits undergo FEC encoding to produces a block of coded bits which are interleaved and punctured to achieve the desired coding rate. These are then mapped to a QPSK or 16QAM symbol constellation. The data symbols produced are then allocated to OFDM subcarriers as specified by the OFDMA multiplexing scheme of each standard, after which IFFT processing is applied to convert the signal to time-domain. Direct OFDMA is implemented for LTE downlink and WiMAX uplink/downlink. However, DFT-spread OFDMA (also called SC-FDMA) is implemented for LTE uplink as specified in the standards. The received signal in the time-domain, having experienced TWTA non-linearity, multipath channel distortion and additive white Gaussian noise, undergoes FFT processing to recover the data symbols allocated to the OFDM subcarriers. The channel response is estimated and compensated for in these subcarriers (Ideal estimation implemented in the current version), after which the signal is demultiplexed, de-mapped, de-interleaved and decoded to recover the block of bits. These bits are then compared with the original transmitted bits in order to establish the bit-error-rate (BER) and/or block-error-rate (BLER). ETSI ETSI TR 101 542 V1.2.1 (2013-07) 27 Figure A.3: Block diagram of the LTE link-level simulator Figure A.4: Block diagram of the WiMAX link-level simulator A.4 FEC, Interleaving and rate matching The binary turbo encoder in the LTE simulator implements a parallel concatenated convolutional code (PCCC) which is similar to HSPA. It consists of two 8-state constituent encoders which are connected to the single information bit input, wherein the second constituent encoder processes an interleaved version of the input. The LTE turbo code internal interleaver implements a quadratic permutation designed to accept a restricted set of block sizes ranging from K = 40 to K = 6 144 and these K values are 188 in total, as specified in [i.9], thereby defining the possible block sizes in LTE. Both LTE and HSPA specify a rate matching algorithm for implementation with the PCCC binary turbo code. This is defined per coded block and consists of three stages: sub-block interleaving, bit collection and bit selection/pruning. The parallel outputs from the rate 1/3 binary turbo encoder undergoes sub-block interleaving, after which the bits are collected as a serial interleaved and interlaced bit stream. They are then passed through a virtual circular buffer for two purposes: bit selection (for the optional HARQ) and bit pruning (puncturing/repetition). The bit selection is achieved by specifying a redundancy version (RV) number which indicates the starting point at which the bits are read out from the buffer. The bit reading process wraps around if the end of the buffer is reached such that reading continues at the beginning of the buffer. Puncturing and/or repetition are achieved by specifying the number of coded bits to be transmitted from the buffer. Block Bit Generator Duo-Binary Turbo Encoder Interleave & Puncture Signal Mapper WiMAX Subchan/ TTI MUX Channel TWTA OFDM Modulation AWGN OFDM Demodulation Signal Demapper Depuncture & DeInterleave Duo-Binary Turbo Decoder BER/ BLER Channel Estimation WiMAX Subchan/ TTI DEMUX Block Bit Generator Binary Turbo Encoder Rate Matching Signal Mapper LTE RB/TTI MUX Channel TWTA OFDM Modulation AWGN OFDM Demodulation LTE RB/TTI DEMUX Signal Demapper De-Rate Matching Binary Turbo Decoder BER/ BLER Channel Estimation ETSI ETSI TR 101 542 V1.2.1 (2013-07) 28 On the other hand, the WiMAX FEC encoder is a tail-biting duo-binary convolutional turbo code (CTC), also referred to as a double binary circular recursive systematic convolutional code. It consists of two constituent encoders, each being connected to the two information bit inputs. Each constituent encoder consists of three circulation states and the output is a rate 1/3 mother code, which undergoes sub-block interleaving and puncturing to the higher code rates specified in [i.1]. The WiMAX CTC sub-block interleavers support only 17 block bit sizes, ranging from 48 to 4 800. Sub-block interleaving and bit collection mechanisms help to support the optional HARQ. Puncturing is performed in accordance with specified number of coded bits per encoded block size such that the desired code rate is achieved. After puncturing, all encoded data bits are interleaved by a block channel interleaver, which is defined according to block size and consists of a two-step permutation [i.10]. A.5 Subcarrier multiplexing LTE specifies two categories of subcarrier mappings by using virtual resource blocks (VRB) which are mapped to physical resource blocks (PRB) according to predefined permutations. A virtual resource block has the same size as a physical resource block and VRB allocations are either of localized or distributed type [i.8],[i.17]. For either type, a single VRB number is used to allocate a pair of virtual resource blocks over two slots in a subframe. In the localized VRB, virtual resource blocks are mapped directly to physical resource blocks in a contiguous manner. On the other hand, the distributed subcarrier allocation maps each VRB to its corresponding PRB using some predefined permutations in order to achieve frequency diversity. The localized and distributed subcarrier multiplexing for two resource blocks in LTE uplink and downlink are illustrated in figures A.5 and A.6 respectively. Subcarrier allocation in WiMAX depends according to the selected mode. The PUSC mode implements a frequency diversity scheme which is specified separately for both uplink and downlink configurations. WiMAX PUSC makes use of logical tiles/clusters to implement an outer permutation for frequency diversity [i.18]. In addition, an inner permutation which consists of intra-subchannel interleaving (over the relevant logical tiles) is performed in the uplink, while the downlink makes use of intra-group interleaving, wherein each group consists of a large number of clusters which are mapped over many subchannels. The outer and inner permutations combine with the smaller time duration of WiMAX PUSC tiles/clusters to achieve robust frequency diversity. Figures A.7 and A.8 illustrate the diversity subcarrier multiplexing of WiMAX for three subchanels in uplink and downlink PUSC respectively. 2 4 6 8 1012 5 10 15 20 25 30 35 40 45 OFDM Symbols Subcarriers Figure A.5: Localized VRB multiplexing in LTE UL ETSI ETSI TR 101 542 V1.2.1 (2013-07) 29 2 4 6 8 1012 5 10 15 20 25 30 35 40 45 OFDM Symbols Subcarriers Figure A.6: Distributed VRB multiplexing in LTE DL 2 4 6 8 1012 5 10 15 20 25 30 35 40 45 OFDM Symbols 1 to 12 Subcarriers 105 to 152 Figure A.7: Diversity multiplexing in WiMAX UL PUSC ETSI ETSI TR 101 542 V1.2.1 (2013-07) 30 2 4 6 8 1012 5 10 15 20 25 30 35 40 45 Subcarriers 49 to 96 OFDM Symbols 1 to 12 Figure A.8: Diversity multiplexing in WiMAX DL PUSC ETSI ETSI TR 101 542 V1.2.1 (2013-07) 31 Annex B: Detailed link-level results B.1 Overview In this clause, link-level simulation results are presented for HSPA in comparison with LTE and WiMAX based on the simulation parameters specified in the previous clause. Eight iterations are implemented in the turbo decoders and a target BLER = 10-3 is selected as it represents a good measure of the desirable link quality for data services [i.3]. For the OFDM-based standards, it is assumed that no extra power is lost due to transmission of the CP, which will be the case if an empty guard interval is used. However, it should be noted that the use of a CP results in a wastage of transmit power by the ratio S G T T . Consequently, an 0,97 dB increase in required o b N E (corresponding to 25 % CP) will apply to the LTE/WiMAX results. The HSPA Rake receiver is configured to track all the received channel paths and combine them optimally. The code orthogonality factor (α ) for downlink HSPA transmission varies in wideband channels and typically lies between 0,4 and 0,9 [i.3]. Therefore, in terms of setting the o b N E values for HSDPA, the input parameters to the simulator are the or c I E and oc or I I . Consequently, α should be determined in order to accurately set the o b N E using (2.1). In order to determine α for a particular multipath channel, we test out different combinations of or c I E and oc or I I (within the acceptable range of a specific link) that achieve the same BLER. This technique is further described in [i.21]. Based on these repeated trials, it was determined that (at 120 km/h) α = 0,89 for MAESTRO channel 1 and α = 0,56 for channel 5. The greater loss of orthogonality in channel 5 can be explained by the fact that it has a high number of channel taps with wide delay spread and its only Rician tap has a very little proportion of the total channel power. Pilots are included in the transmission but ideal synchronization and perfect channel estimation are implemented so that performance can be compared independent of estimation algorithms. 10 % of the power in HSDPA is allocated to the CPICH which is transmitted alongside the HS-DSCH. For HSUPA, 20 % of the power is allocated to the DPCCH as specified in [i.21]. On the other hand, all used subcarriers (pilot and data) in the current LTE/WiMAX simulators share power equally, meaning that 5,6 % power is allocated to the pilots in LTE DL, 16,7 % for LTE UL, 14,3 % in WiMAX UL and 33,3 % in WiMAX DL. Results pertaining to HSDPA are denoted as 'HD', HSUPA as 'HU', LTE as 'L' and WiMAX as 'W'. B.2 Downlink performance comparison Figures B.1 to B.5 shows BLER results for HSDPA in comparison with LTE DL and WiMAX DL, all based on the 5 MHz bandwidth configuration. In figure B.1, it can be seen that 2,4 Mbps HSDPA achieves a target BLER = 10-3 with o b N E less than 7 dB for MAESTRO channel 1 in contrast to 2,3 Mbps LTE and 2,1 Mbps WiMAX which achieve this target at ~8 dB. This can be attributed to the fact that HSDPA makes use of a larger block size and larger TTI duration to achieve a similar data rate with LTE/WiMAX. Therefore it benefits from increased coding and interleaving gains respectively but at the expense of increased latency. The performance trend is retained for channel 5 profile but it can be noticed that the o b N E gap between HSDPA and LTE/WiMAX increases. This is due to a combination of multipath diversity gain (achieved via Rake reception of many channel taps) and multiple access interference resulting from the low code orthogonality factor of channel 5. However, having a high number of Rake fingers is not usually practical for a user terminal. It can be noticed that at ~4,5 dB, o b N E saturation occurs for 2,4 Mbps HSDPA due to its low processing gain and the low orthogonality factor of channel 5, such that the target BLER = 10-3 is never achieved despite increasing the geometry factor to very high values. In contrast, LTE and WiMAX achieve the target BLER at ~8 dB similar to their performance in channel 1. The frequency diversity gain of channel 5 is better than that of channel 1 (due to its larger delay spread) and this takes on greater significance in link performance of LTE/WiMAX as additive noise reduces. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 32 0 2 4 6 8 10 10 −4 10 −3 10 −2 10 −1 10 0 Eb/N0 (dB) BLER HD−4800−Ch.1 HD−4800−Ch.5 L−2304−Ch.1 L−2304−Ch.5 W−2880−Ch.1 W−2880−Ch.5 Figure B.1: DL performance comparison (TWTA linear) 0 2 4 6 8 10 10 −3 10 −2 10 −1 10 0 Eb/N0 (dB) BLER HD−3200−Linear−Ch.1 HD−3200−IBO=0−Ch.1 HD−3200−Linear−Ch.5 HD−3200−IBO=0−Ch.5 Figure B.2: HSDPA performance; N = 3 200 Eb/N0 saturation ETSI ETSI TR 101 542 V1.2.1 (2013-07) 33 0 2 4 6 8 10 10 −3 10 −2 10 −1 10 0 Eb/N0 (dB) BLER HD−4800−Linear−Ch.1 HD−4800−IBO=0−Ch.1 HD−4800−Linear−Ch.5 HD−4800−IBO=0−Ch.5 Figure B.3: HSDPA performance; N = 4 800 2 4 6 8 10 12 10 −4 10 −3 10 −2 10 −1 10 0 Eb/N0 (dB) BLER L−2304−Linear−Ch.1 L−2304−IBO=0−Ch.1 L−2304−Linear−Ch.5 L−2304−IBO=0−Ch.5 Figure B.4: LTE DL performance Eb/N0 saturation Eb/N0 saturation ETSI ETSI TR 101 542 V1.2.1 (2013-07) 34 1 2 3 4 5 6 7 8 9 10 11 10 −4 10 −3 10 −2 10 −1 10 0 Eb/N0 (dB) BLER W−2880−Linear−Ch.1 W−2880−IBO=0−Ch.1 W−2880−Linear−Ch.5 W−2880−IBO=0−Ch.5 Figure B.5: WiMAX DL performance Figure B.2 shows the 1,6 Mbps HSDPA performance wherein a block size of N = 3 200 is used in contrast to N = 4 800 used for 2,4 Mbps HSDPA. Comparing the TWTA linear region with figure B.1, it can be seen that both transmissions achieve a similar link performance for channel 1, with the 2,4 Mbps having little superiority due to increased coding gain. However, the 1,6 Mbps transmission is able to achieve the target BLER at o b N E less than 5 dB for channel 5 in contrast to the 2,4 Mbps transmission, thanks to its increased processing gain. The effect of a TWTA operating at saturation point (0 dB) is also shown in figure B.2 wherein ~2 dB degradation in performance is noticed. This is due to the fact that 1,6 Mbps HSDPA uses multi-code transmission (10 channelization codes) to achieve the given data rate and these parallel codes introduce a high PAPR in the forward link signal. In comparison, the 2,4 Mbps transmission suffers from a higher degradation of ~3 dB in the presence of TWTA non-linearity as shown in figure B.3. This is due to the increased multi-code transmission (15 channelization codes) which increases the PAPR of the signal. It is also noticed that the channel 5 BLER for 2,4 Mbps is very poor in the presence of amplifier non-linearity due to o b N E saturation at ~4,5 dB as explained earlier. LTE and WiMAX also experience degradation in the downlink due to the high PAPR of OFDM transmissions as shown in figures B.4 and B.5, with an increase of ~2 dB in the required o b N E for 2,4 Mbps LTE and 2,1 Mbps WiMAX services. Therefore, amplifier non-linearity is an issue for all the standards and this effect can be mitigated by using signal power back-off in the amplifier and/or digital pre-distortion [i.15]. Table B.1 gives more insight into the performance of HSDPA for high data rate transmission in wideband channels. Although the 1,6 Mbps transmission (N = 3 200) in channel 5 is able to achieve BLER < 10-3 at o b N E less than 5 dB (in contrast to the 7 dB needed for channel 1), it actually demands more link resources. For a fixed or c I E = -1 dB, channel 5 requires a geometry factor of 20 dB to achieve the target BLER in contrast to 7,17 dB required by channel 1. This is due to the greater loss of code orthogonality in the channel and means that the 1,6 Mbps service cannot be provided with wide coverage (as this will generate unacceptable interference to neighbouring cells). Table B.1: HSDPA simulator input and output Profile oc or I I (dB) or c I E (dB) α o b N E (dB) BLER HD-4 800-Linear-Ch.1 13,02 -1 0,89 7 0,000 HD-4 800-Linear-Ch.5 20 -1 0,56 4,5 0,200 HD-3 200-Linear-Ch.1 7,17 -1 0,89 7 0,000 HD-3 200-Linear-Ch.5 20 -1 0,56 5 0,000 ETSI ETSI TR 101 542 V1.2.1 (2013-07) 35 B.3 Uplink performance comparison Figures B.6 to B.8 show BLER results for HSUPA in comparison with LTE UL and WiMAX UL, all based on the 5 MHz bandwidth configuration. In figure B.6, it can be seen that similar to the downlink performance, 1,92 Mps LTE and 1,4 Mbps WiMAX achieve a target BLER = 10-3 with o b N E = ~8 dB for high user data rate transmission in MAESTRO channel 1. However, in the presence of amplifier non-linearity, LTE experiences a degradation of ~1 dB whereas WiMAX experiences ~2 dB degradation. This is due to the fact that LTE uses SC-FDMA (DFT-spread OFDMA) in its uplink in contrast to the direct OFDMA used in WiMAX and SC-FDMA has a lower PAPR than direct OFDMA. 0 2 4 6 8 10 12 10 −4 10 −3 10 −2 10 −1 10 0 Eb/N0 (dB) BLER L−1920−Linear−Ch.1 L−1920−IBO=0−Ch.1 W−1920−Linear−Ch.1 W−1920−IBO=0−Ch.1 Figure B.6: LTE and WiMAX UL performance (short TTI) In order to make a good comparison in figures B.7 and B.8, the LTE and WiMAX uplinks are modified to have a longer TTI of ~10 ms in order to achieve a similar interleaving gain with the HSUPA simulator (which has the 10 ms TTI implemented). By matching the interleaving gains, it is expected that the results achieved will reflect a parallel comparison for the optional 2 ms TTI in HSUPA. A longer TTI will always benefit the link performance in terms of interleaving gain but at the expense of link latency. Figure B.7 shows that 0,256 Mbps HSUPA and 0,256 Mbps LTE achieve a comparable link performance for MAESTRO channel 1. However, the performance of 0,2 Mbps WiMAX is significantly better due to its higher frequency diversity gain, achieved by diversity subcarrier multiplexing (as shown in figure B.7) in contrast to the localized subcarrier multiplexing of LTE UL (as shown in figure B.5). It is noted that localized multiplexing in LTE UL is needed to achieve the full benefits of SC-FDMA in the presence of amplifier non- linearity. In figure B.8, HSUPA is shown to maintain its link performance in the presence of amplifier non-linearity whereas LTE and WiMAX experience degradation. This is due to a single-user, single-code transmission used in HSUPA (which implies a PAPR = ~1). Despite the higher frequency diversity gain of WiMAX, LTE achieves a better performance under amplifier saturation due to the lower PAPR of SC-FDMA in comparison to the direct OFDMA of WiMAX. As was shown in the downlink results, multi-code transmission in WCDMA leads to increased PAPR of the transmitted signal, thereby resulting in greater degradation under amplifier non-linearity. ETSI ETSI TR 101 542 V1.2.1 (2013-07) 36 0 1 2 3 4 5 10 −4 10 −3 10 −2 10 −1 10 0 Eb/N0 (dB) BLER HU−2560−Linear−Ch.1 L−2560−Linear−Ch.1 W−1920−Linear−Ch.1 Figure B.7: Uplink performance comparison, linear TWTA (long TTI) 0 1 2 3 4 5 6 7 10 −4 10 −3 10 −2 10 −1 10 0 Eb/N0 (dB) BLER HU−2560−IBO=0−Ch.1 L−2560−IBO=0−Ch.1 W−1920−IBO=0−Ch.1 Figure B.8: Uplink performance comparison, saturated TWTA (long TTI) ETSI ETSI TR 101 542 V1.2.1 (2013-07) 37 History Document history V1.1.1 May 2012 Publication V1.2.1 July 2013 Publication |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 1 Scope | The present document presents the results obtained on technological platform where Triple Play offers are available. These results concern the quality evaluation of IPTV video streams produce by the offers available on the platform. The determinate indicators are presented in the main part of the document. The results were obtained during a specific test campaign for SD streams analysis. Note that determinate indicators are presented in ES 202 765-4 [i.1]. So the present document represents an implementation report for some metrics and associated methods defined in ES 202 765-4 [i.1]. The main part of the present document presents the performed indicators and charts used for results presentation. Annex A presents the methodology implemented in a first series of tests and the results. |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 2 References | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 2.1 Normative references | The following referenced documents are necessary for the application of the present document. Not applicable. |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 2.2 Informative references | The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] ETSI ES 202 765-4: "Speech and multimedia Transmission Quality (STQ); QoS and network performance metrics and measurement methods; Part 4: Indicators for supervision of Multiplay services". [i.2] ITU-T Recommendation P.505: "One-view visualization of speech quality measurement results". [i.3] ITU-T Recommendation J.247: "Objective perceptual multimedia video quality measurement in the presence of a full reference". [i.4] ITU-T Recommendation J.144: "Objective perceptual video quality measurement techniques for digital cable television in the presence of a full reference". ETSI ETSI TR 101 565 V1.1.1 (2011-09) 6 |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 3 Definitions and abbreviations | |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: platform: premise installed in residential environment where the accesses to different Multi Play offers proposed by ISP on the same country are made available NOTE: This platform is generally installed in the centre of a city. |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 3.2 Abbreviations | For the purposes of the present document, the following abbreviations apply: ADSL Asymmetric Digital Subscriber Line DVB-T Digital Video Broadcasting - Terrestrial HGW Home GateWay NOTE: Referenced also as Residential Gateway. IP Internet Protocol IPTV IP TeleVision NOTE: System where a digital television service is delivered using Internet Protocol. ISP Internet Service Provider ITU-T International Telecommunication Union - Telecommunication standardization sector MOS Mean Opinion Score VoIP Voice over Internet Protocol |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 4 Context | The deployment of multiplay offers is increasing, so it is important to measure quality performances of services proposed via these multiplay offers. Concerning performance evaluation of multiplay offers, ES 202 765-4 [i.1] lists indicators and presents methodologies for quality characterization in a context of end-user. The present document gives practical requirements of use in the context of service verification and benchmark. Multiplay offers developed on IP technology give access to IPTV services. These IPTV services develop in an important way in the residential context. But contrary to the VoIP services, performances of IPTV services of are not really evaluated. Because there is a necessity of having a performance overview of the service brought to the users, the actors of the domain (operators, benchmakers) began to perform evaluations of IPTV services. In these conditions, the present document presents a benchmark of the video quality evaluated on different TV services. The present document is intended to provide an overview of the performance of IPTV offers deployed in France (and used by customers). The core of the report presents determined metrics and results presentation. The results presented in annex A of the present document, concern video quality of IPTV service associated to Triple Play offers implemented on the technological platform installed in a city in France. The interest of these results is to give an overview of video quality of deployed IPTV services compared to a kind of reference which is the video quality of DVB-T (Digital Video Broadcasting - Terrestrial) service. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 7 |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 5 Platform presentation | The platform is a premise installed in residential environment and in which there are the accesses to different Multi Play offers proposed by ISP on the same country. The technological platform used for performing video quality assessment is installed in a premise in the city centre of a town counting more than 210 000 residents. During the second semester of 2010, this platform was characterized by: • Implementation of 6 offers concerning 6 different ISPs. • Each offer proposes 3 services: Internet access, VoIP and IPTV. • Access to services is obtained through a Home GateWay (HGW). • Access to the network can be ADSL or cable type depending on the ISP. • Distance between HGW and first digital equipment is about 350 meters (Length of the ADSL line). • A DVB-T (Digital Video Broadcasting - Terrestrial) access is also available. So in the platform, there are 7 different TV accesses: 6 IPTV accesses and 1 DVB-T access. Figure 1 shows an overview of the architecture and a synopsis of the platform in the context of TV services. Figure 1: Architecture overview of TV service broadcasting |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 6 Presentation of test conditions | To assess the video quality of the different TV services, the principles are to analyze several video sequences belonging to different channels. TV TV TV STB HGW STB HGW DVB-T Receiver Access Node Backhaul IP Backbone TV production platform POP Access Residential domain Architecture Overview Broadcast station 1 2 1 2 Classical TV service IPTV services ETSI ETSI TR 101 565 V1.1.1 (2011-09) 8 |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 6.1 Indicator description | To take into account the end user context, only objective measurements models based on No Reference approach correspond to the need. The current issue is that there is no standardized algorithm in that area. The ITU-T Recommendation J.247 [i.3] is not applicable in this context because J.247 is a model functioning with reference. J.144 [i.4] is also not applicable in this context due to these restrictions (synchronisation issues, not application to MPEG4). For the time being, it is proposed to qualify video quality by the occurrence of particular degradations like "black screen", blockiness and frozen picture. So in this context, the indicators are the following ones. |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 6.1.1 "Black Screen" Occurrences | Definition Currently, a major trouble of IPTV service is the fact of having displayed on the TV set a "black screen". Black screen can outcome from: • encoder / decoder implementation when no video stream is present • a major loss of video packet during a long period of time This metric correspond to the number of black screen sequence during a time period (24 hours, 1 week…). "Black screen" is one of the cases of "isochrominance". Assessment method This default is detected mainly by using robots or probes implementing objective video signal measurement algorithms that are able to detect an image fully coloured in black. Currently, this is the most suitable approach so as to perform a consistent signal-based analysis. Unit Number or Ratio (number of occurrence by time unit). Standardization reference ES 202 765-4 [i.1]. Comment The duration of the measurement should be greater than the "inter-advertisements" duration, because sometimes the broadcasters insert "black screen" sequences not visible by the users between advertising. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 9 |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 6.1.2 Blockiness Occurrences | Definition In video and image compression, a common artifact called "Blockiness" comes firstly from low-quality compression when too few bits are used. This artifact can be appeared when packet loss ratio is too high packet loss ratio on the transmission link (operator network, user installation…). Blockiness is an obviously perceptible contrast of color at the boundaries of the encoding blocks with a codec like JPEG or MPEG video. This metric correspond to the number of blockiness sequence during a time period (24 hours, 1 week…). B-3 block Group of pels. For example, a block of 8x8 pels is the smallest coding block used in MPEG-1 algorithms. There are 1 320 blocks in a CIF image, 44 in the horizontal direction (352 pels/8) and 36 in the vertical direction (288 lines/8). B-4 block distortion Distortion of the image characterized by the appearance of an underlying block encoding structure, also called tiling. E-22 error blocks A form of block distortion where one or more blocks in the image bear no resemblance to the current or previous scene and often contrast greatly with adjacent blocks. Assessment method This default is mainly detected by using robots or probes that implement objective video signal measurement algorithms that are able to detect it. Currently, this is the most suitable approach so as to perform a consistent signal-based analysis. These measurements may be done by taking into account the STB integrating error recovery. Unit Number or Ratio (number of occurrence by time unit). Standardization reference ES 202 765-4 [i.1] Comment It is often referred to macro blocking, this occurs when a certain amount of the IPTV streams are unavailable to the Set Top Box at playout time. This is most commonly due to packet loss at some point in the network but could be due to everything from content encoding issues to delay-variations (jitter) as packets arrive too late to the STB. |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 6.1.3 Frozen Picture Occurrences | Definition The frozen picture phenomena can be expressed through some pictures appearing as stopped / freezed from time to time on the end-user screen. These freezes may be issued by the decoder or the network. There are usually very annoying for the end-user. This metric correspond to the number of freezed picture sequence during a time period (24 hours, 1 week…). Assessment method In practical way, this indicator can be measured by verifying on adjacent image the stability of the luminance and\or the chrominance components and this for all pixels composing an image. Unit Number or Ratio (number of occurrence by time unit). Standardization reference ES 202 765-4 [i.1]. Comment As for "black screen" it is needed to make the measurement on a duration greater than 1 second (typically during 8 seconds or more). |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 6.2 Result presentations | To present results, 2 type of presentation are used in the present document: • Sector presentation • Pie diagram For this first experiment, it is proposed to determine the number of impaired video sequences for each TV service and for each TV program. It is reminded that a video sequence is considered as impaired as soon as one impairment is detected. The number of different impairment types (such as blockiness, frozen and monochromatic screens) is also determined. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 10 As an example for Channel n°2, over the 105 video sequences the following impairments re the following: • 1 monochromatic screen • 9 frozen screens • 1 blockiness As a consequence the video quality is defined as 1% of monochromatic screen, 9% of frozen screen and 1% blockiness. |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 6.2.1 "Sector" presentation | The "sector" display consists in displaying the percentage of impaired and non-impaired video sequences on one circle. The whole display is defined by one circle by impairment. One example is provided in figure 2. NOTE: This type of graph presents the ratio of specific degradations (Monochrome screen, Freeze and Blockiness) in video sequences. Figure 2: Example of Sector presentation: 3 metrics determined on a TV channel |
ed86697c8152da05d85e1b88fbb9fb5c | 101 565 | 6.2.2 Pie diagram presentation | Another interesting presentation is used in the present document. It is the Pie diagram (ITU-T Recommendation P.505 [i.2]). This type of presentation offers on a single figure an overview of the performances. It is possible to present several metrics on the same graph by maintaining each indicator on its own scale. This type of presentation allows to easily displaying the strengths and weaknesses of each offer. The Pie diagram also allows to easily comparing the offer performances. Within the framework of this platform, 3 indicators by channel are presented on a Pie Diagram (ITU-T recommendation P.505 [i.2]). These 12 indicators correspond to 3 metrics ("Black Screen" ratio, Blockiness ratio and Frozen Picture ratio) by channel and for 4 TV channels analysed. These indicators are presented in reference to two arbitrary thresholds: 0 % and 10 %. The 10 % threshold is represented by a red circle. The indicator value is green above and yellow below the threshold. If the indicator value is between 0 % and 10 %, the indicator is presented in light green. Dark green is used to present indicator characterizing 0 % degradation. To facilitate the visualization of performances associated to each TV channel, a specific line separates the results by channel. An example of this type of graph is presented on figure 3. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 11 Channel 1 Monochrome 3 10 21 14 7 0 Channel 1 Freeze 21 10 21 14 7 0 Channel 1 Blockiness 6 10 21 14 7 0 Channel 2 Monochrome 11 10 21 14 7 0 9 Channel 2 Freeze 10 21 14 7 0 0 Channel 2 Blockiness 10 21 14 7 0 19 Channel 3 Monochrome 10 21 14 7 0 17 Channel 3 Freeze 10 21 14 7 0 9 Channel 3 Blockiness 10 21 14 7 0 2 Channel 4 Monochrome 10 21 14 7 0 Channel 4 Freeze 17 10 21 14 7 0 Channel 4 Blockiness 0 10 21 14 7 0 Figure 3: Example of Pie diagram with indicators determined in the context video quality evaluation (3 metrics determined on 4 IPTV channels) ETSI ETSI TR 101 565 V1.1.1 (2011-09) 12 Annex A: Video quality performance evaluated on different IPTV services - Overview of results obtained at end 2010 A.1 Platform presentation On the platform, there are 7 different TV accesses: 6 IPTV accesses and 1 DVB-T access. The DVB-T access characterization shows that receiving conditions are very good: only 20 km between the broadcast antenna and the platform, high level for the receiving signal into the premise, very low error bit rate… The DVB-T access characterization is done on the received signal at the antenna output located in the test room. This characterization does not qualify the media flow! In this condition, TV service over DVB-T access is a sort of comparison point for this benchmark. NOTE: The characterization of DVB-T access was realized on the receiving signal before the receiver directly at the antenna output. Figure A.1: In the premise where the technical platform is installed A.2 Description of the methodology The equipment needed to conduct such an experiment is rather heavy. So we have only one analyzer to lead this study. So, the different characterizations are realized in sequence and not in parallel implying to define the whole implementation described below. A.2.1 General Principles As it is not possible to make all the tests in parallel, as one of the intention of the experiment is to compare the video quality of all the offers, it is needed to select carefully the time period for the test (corresponding to a rather high percentage of viewers), the most popular video programmes (for children, seniors, workers, non-active...) which have to be provided by all the ISPs and by DVB-T. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 13 These principles are summarized in figure A.2): Figure A.2: Principles used to characterize video quality of TV services Based on the principles described above the choice of the video sequences is described in figure 4. The channel choice is based on three criteria: • A selection of TV channels that are known and watched by a lot of people. This selection corresponds to a high representativity based on the "Audimat" percentage of viewers. • The TV channels are viewed by different age categories such as children, seniors, workers • The TV channels are all available in the different groups offered by the ISPs and also available in the DVB-T groups. NOTE: In France "Audimat" is the company in charge of the monitoring of TV channel audience. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 14 Figure A.3: The 4 channels used for video characterization are common of all IPS channel groups The TV programs choice and consequently the timeslots choice correspond to the need to have the same kind of contents every day at the same hour. As the analysis is done sequentially for the different ISPs, it is absolutely requested to check that the different analysis is done on similar contents. For this first experiment the selection, of choice for channels and TV programs are the following: • The Channel number 1of a public TV provides all types of programs but the choice has been done on the news program at the beginning of the evening. This program is mainly viewed by workers. • The Channel number 2 of a public TV provides all types of programs but the choice has been done on a game at the end of the afternoon, mainly viewed by seniors. • The Channel number 3 of a private TV provides programs dedicated to cartoons and is mainly viewed in the beginning of the morning by young children. • The Channel number 3 of a private TV provides all types of programs but the choice has been done on the news program at lunch time. This program is mainly viewed by people without professional activities and medium age. Each TV program duration is about 30 / 35 minutes every day. A.2.2 Technical criteria It could be relevant to assess the quality for SD and for HD TV. For this first experiment only the SD (Simple Definition) quality is assessed. So all the TV channels and programs are in SD quality. To capture the video flow, a HDMI link is used between the STB (for TV services over IP) and the analyzer. We also used a HDMI link (between the DVB-T receiver and the analyzer) to analyze the video flow of the DVB-T service. It has also been checked that image resolution at the output of the STB is the same as at the output of the DVB-T receiver whatever the ISP and the channel. This resolution is 1 920 x 1 080i for all the ISPs except one which has a smaller resolution (720x576i). This ISP has not been kept in the panel. Finally the tests are made on 5 IPTV services provided by 5 different ISPs and 1 TV service. It should be noted that for IPTV services 4 of them are IP over an ADSL line and 1 is IP over cable. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 15 A.2.3 Scheduling of analyses For each TV program the video quality analysis is done on 10 seconds sequences. The test sequences are built as follows: 1) 3 successive video sequences of 10 s are recorded. 2) Each of the 3 recorded sequences is analyzed. This process 1 and 2 is repeated all along the TV program. The analysis duration for 3 video sequences of 10 seconds is about 5 minutes. So, every 5 minutes 3 TV sequences are recorded and analyzed. In order to obtain a sufficient enough number of video sequences analysis, the same TV program is analyzed over several consecutive days (in practice 5 days). At the end, 105 TV sequences are recorded and analyzed for each ISP. Globally for the 6 TV services (5 IPTV and 1 DVB-T) and for the 4 programs 2 520 video samples have been analyzed. Figure A.4: Analyse scheduling and detection of video quality impairments As shown on figure A.4 the main objective is to detect the video quality impairments (blockiness, frozen or monochromatic images) on the 10 seconds sequences. When impairment is detected in a 10 seconds video sequence, the whole sequence is considered as impaired. A.3 Results obtained by IPTV service of ISP1 For the two metrics "Monochrome" and "blockiness" the percentage of impaired sequences is between 0 % and 1 %, whatever the channels. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 16 The "freeze" metric is detected on the four channels but it is extremely high for channel 3 (94 %) and rather low for channel 1 (5 %). For channels 2 and 4 the percentage of impaired sequences are respectively 12 % and 19 %. Figure A.5 Channel 1 Monochrome 0 10 21 14 7 0 Channel 1 Freeze 5 10 21 14 7 0 Channel 1 Blockiness 0 10 21 14 7 0 Channel 2 Monochrome 1 10 21 14 7 0 12 Channel 2 Freeze 10 21 14 7 0 1 Channel 2 Blockiness 10 21 14 7 0 0 Channel 3 Monochrome 10 21 14 7 0 94 Channel 3 Freeze 10 21 14 7 0 0 Channel 3 Blockiness 10 21 14 7 0 0 Channel 4 Monochrome 10 21 14 7 0 Channel 4 Freeze 19 10 21 14 7 0 Channel 4 Blockiness 0 10 21 14 7 0 Figure A.6 ETSI ETSI TR 101 565 V1.1.1 (2011-09) 17 A.4 Results obtained by IPTV service of ISP2 For the two metrics "Monochrome" and "blockiness" the percentage of impaired sequences is between 0 % and 2 %, whatever the channels. The "freeze" metric is detected on the four channels but it is high (more than half of the sequences are impaired) for channel 3 (60 %). For the three other channels the percentages of impaired sequences are bigger than 10 %, the channels 2, 1 and 4 the percentage of impaired sequences are respectively 12 %, 13 % and 26 %. Figure A.7 ETSI ETSI TR 101 565 V1.1.1 (2011-09) 18 Channel 1 Monochrome 0 10 21 14 7 0 Channel 1 Freeze 13 10 21 14 7 0 Channel 1 Blockiness 0 10 21 14 7 0 Channel 2 Monochrome 1 10 21 14 7 0 12 Channel 2 Freeze 10 21 14 7 0 0 Channel 2 Blockiness 10 21 14 7 0 0 Channel 3 Monochrome 10 21 14 7 0 60 Channel 3 Freeze 10 21 14 7 0 2 Channel 3 Blockiness 10 21 14 7 0 0 Channel 4 Monochrome 10 21 14 7 0 Channel 4 Freeze 26 10 21 14 7 0 Channel 4 Blockiness 0 10 21 14 7 0 Figure A.8 A.5 Results obtained by IPTV service of ISP3 For the two metrics "Monochrome" and "blockiness" the percentage of impaired sequences is 0 % for the different channels, except for "Monochrome" on Channel 2 which reaches 3 %. The "freeze" metric is detected on the four channels but it is very high for channel 3 (86 %) and at 10 % for channels 1 and 2 (10 %). For channel 4 the percentage of impaired sequences is 26 %. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 19 Figure A.9 Channel 1 Monochrome 0 10 21 14 7 0 Channel 1 Freeze 10 10 21 14 7 0 Channel 1 Blockiness 0 10 21 14 7 0 Channel 2 Monochrome 3 10 21 14 7 0 10 Channel 2 Freeze 10 21 14 7 0 0 Channel 2 Blockiness 10 21 14 7 0 0 Channel 3 Monochrome 10 21 14 7 0 86 Channel 3 Freeze 10 21 14 7 0 0 Channel 3 Blockiness 10 21 14 7 0 0 Channel 4 Monochrome 10 21 14 7 0 Channel 4 Freeze 26 10 21 14 7 0 Channel 4 Blockiness 0 10 21 14 7 0 Figure A.10 ETSI ETSI TR 101 565 V1.1.1 (2011-09) 20 A.6 Results obtained by IPTV service of ISP4 For the two metrics "Monochrome" and "blockiness" the percentage of impaired sequences is between 0 % and 1 %, whatever the channels. The "freeze" metric is detected on the four channels but the percentage of impaired sequences is lower than for the other ISPs. For channel 3 more than ¼ of the sequences are impaired (28 %). For the three other channels the percentages of impaired sequences are respectively 4 %, 12 % and 14 % for channels 1, 2 and 4. Figure A.11 Channel 1 Monochrome 0 10 21 14 7 0 Channel 1 Freeze 4 10 21 14 7 0 Channel 1 Blockiness 0 10 21 14 7 0 Channel 2 Monochrome 1 10 21 14 7 0 12 Channel 2 Freeze 10 21 14 7 0 0 Channel 2 Blockiness 10 21 14 7 0 0 Channel 3 Monochrome 10 21 14 7 0 28 Channel 3 Freeze 10 21 14 7 0 0 Channel 3 Blockiness 10 21 14 7 0 0 Channel 4 Monochrome 10 21 14 7 0 Channel 4 Freeze 14 10 21 14 7 0 Channel 4 Blockiness 0 10 21 14 7 0 Figure A.12 ETSI ETSI TR 101 565 V1.1.1 (2011-09) 21 A.7 Results obtained by IPTV service of ISP5 For the two metrics "Monochrome" and "blockiness" the percentage of impaired sequences is between 0% and 1%, whatever the channels. For the three other channels the percentages of impaired sequences are respectively 13% for channel 1 and 17 % for channels 2 and 4. Figure A.13 Channel 1 Monochrome 0 10 21 14 7 0 Channel 1 Freeze 13 10 21 14 7 0 Channel 1 Blockiness 0 10 21 14 7 0 Channel 2 Monochrome 1 10 21 14 7 0 17 Channel 2 Freeze 10 21 14 7 0 0 Channel 2 Blockiness 10 21 14 7 0 0 Channel 3 Monochrome 10 21 14 7 0 91 Channel 3 Freeze 10 21 14 7 0 0 Channel 3 Blockiness 10 21 14 7 0 0 Channel 4 Monochrome 10 21 14 7 0 Channel 4 Freeze 17 10 21 14 7 0 Channel 4 Blockiness 0 10 21 14 7 0 Figure A.14 ETSI ETSI TR 101 565 V1.1.1 (2011-09) 22 A.8 Results obtained by TV service of DVB-T Initially it was intended to use the DVB-T service as the reference for quality. However, the results shown for DVB-T indicate that the three metrics are impaired (except for "blockiness" on channels 2 and 4). "Monochrome" metric is respectively observed on 1 % of sequences for channels 1 and 2, and on 7 % for channel 3. "Blockiness" metric is observed as 1 % of sequences for channel 1 and as 2 % on channel 3. Even if "freeze" metric does not seem as important as for IPSs it can be seen that the percentage of "freeze" sequences is respectively 4 % for channel 2, 9 % for channel 1, 27 % for channel 3 and 28 % for channel 4. Figure A.15 ETSI ETSI TR 101 565 V1.1.1 (2011-09) 23 Channel 1 Monochrome 1 10 21 14 7 0 Channel 1 Freeze 9 10 21 14 7 0 Channel 1 Blockiness 1 10 21 14 7 0 Channel 2 Monochrome 1 10 21 14 7 0 4 Channel 2 Freeze 10 21 14 7 0 0 Channel 2 Blockiness 10 21 14 7 0 7 Channel 3 Monochrome 10 21 14 7 0 27 Channel 3 Freeze 10 21 14 7 0 2 Channel 3 Blockiness 10 21 14 7 0 2 Channel 4 Monochrome 10 21 14 7 0 Channel 4 Freeze 28 10 21 14 7 0 Channel 4 Blockiness 0 10 21 14 7 0 Figure A.16 A.9 Result discussion This first test campaign of IPTV quality offered by ISPs and compared with DVB-T shows that the three parameters qualifying the video quality may be assessed in "real time" and validates the principles defined in ES 202 765-4 [i.1]. The results on the three metrics ("Monochromatic", "Freeze" and "blockiness") do not give similar results: the metric "Freeze" is the most common detected, the two other metrics being in general rather low for the most of the ISP x channel. It is also seen that the "Freeze" metric is observed on the different channels and for all the ISPs but it seems that Channel 3 is more affected than the others. As Channel 3 proposes mainly cartoons, it should be needed to check carefully the results: the cartoons are sometimes produced by creating a limited number of pictures, compared to the number of video image. For such programs it will be perhaps needed to define specific parameters (increase the duration criteria for detection). Globally, ISP 4 provides a lower percentage of frozen pictures. An observation that was not expected is to discover that DTT also provides a rather large percentage of impaired video sequences. As a global result, if we consider only indicator without degradation, DVB-T provides the worst quality. The different channels are not impaired in a similar way. Channels 1 and 2 provide better quality than channel 4, channel 3 being identified as the poorest quality channel. ETSI ETSI TR 101 565 V1.1.1 (2011-09) 24 History Document history V1.1.1 September 2011 Publication |
c099f70226392b092615be99cebbaaec | 101 538 | 1 Scope | The present document describes a railway application utilizing ultra wideband technology operating in the preferred frequency ranges from 3,1 GHz to 4,8 GHz and from 6 GHz to 8,5 GHz. Operation is foreseen for indoor and outdoor applications, including either mobile devices installed onboard the train cars and fixed devices installed on ground, as reference stations. These stations, belonging to the fixed infrastructure, will be allowed to operate as UWB emitters only in the lower frequency band, from 3,1 GHz to 4,8 GHz, in compliance with the compatibility studies and with the latest recommendation [i.9] proposed by ECC/CEPT, as this provision would allow the deployment of such fixed UWB devices in the railway environment according to the "registration and coordination" process recently proposed by ECC/CEPT 167 [i.10]. In railway applications, location tracking is performed within specified areas, called as an Area-Of-Interests (AOIs), which are areas around Point-Of-Interests (POIs). The POIs are listed below: • Point in passenger platform • Railway signal • Railway crossing • Generic POI The UWB radio technology is required to track with sub-meter accuracy any rail vehicle to the purpose of stopping it in the appropriate POI. The length of AOI is defined by the braking distance of a rail vehicle, and it is typically hundreds of meters. The generic regulation on UWB technology for use in rail and road vehicles onboard applications, such as - for instance - in subway underground stations, within the frequency ranges of 3,1 GHz to 4,8 GHz and 6 GHz to 8,5 GHz has been recently updated in the last Electronic Communication Committee (ECC) amended ECC/DEC(06)04 [i.1] including the suitable reference to mitigation techniques. According to [i.2], underground station should be considered as an indoor environment because surrounding structures shields any emitted radio signal, providing the necessary attenuation to protect primary radio communication services against harmful interference. However, in railway stations and trackside signalling installations there may not be structures blocking the propagation of emitted signals, and therefore the outdoor environment regulation should apply. The outdoor usage of UWB devices in location and tracking applications such as person and object tracking in industrial, automotive and transportation environments are described in [i.4] and [i.5]. Nevertheless, these applications do not include the location / tracking specific application in railway environments, which may occur at many points across a public rail or tram network. Actually, the latest generic ECC regulation [i.11] for the deployment of UWB devices in vehicles and the ECC/REC(11)09 [i.9] on provisions relevant to fixed UWB infrastructures do not deal with specific railway application issues, but are actually permitting the deployment of such UWB, respectively, onboard the trains and along the wayside of railway infrastructures. Therefore, the present document describes the railway application of UWB devices and collects specific information, including: • Market information (annex A). • Technical information (annex B). ETSI ETSI TR 101 538 V1.1.1 (2012-10) 7 |
c099f70226392b092615be99cebbaaec | 101 538 | 2 References | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the referenced document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. |
c099f70226392b092615be99cebbaaec | 101 538 | 2.1 Normative references | The following referenced documents are necessary for the application of the present document. Not applicable. |
c099f70226392b092615be99cebbaaec | 101 538 | 2.2 Informative references | The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] ECC/DEC/(06)04 of 24 March 2006 amended 6 July 2007 at Constanta on the harmonised conditions for devices using Ultra-Wideband (UWB) technology in bands below 10.6 GHz (2007/131/EC) amended 6 July 2007. [i.2] Commission Decision 2007/131/EC of 21 February 2007on allowing the use of the radio spectrum for equipment using ultra-wideband technology in a harmonised manner in the Community. [i.3] ECC/DEC/(06)12 of 1 December 2006 amended Cordoba, 31 October 2008 on supplementary regulatory provisions to Decision ECC/DEC/(06)04 for UWB devices using mitigation techniques amended 31 October 2008. [i.4] ETSI TR 102 495-5: "Electromagnetic compatibility and Radio spectrum Matters (ERM); System Reference Document; Short Range Devices (SRD); Technical characteristics for SRD equipment using Ultra Wide Band Sensor technology (UWB); Part 5: Location tracking applications type 2 operating in the frequency bands from 3,4 GHz to 4,8 GHz and from 6 GHz to 8,5 GHz for person and object tracking and industrial applications". [i.5] ETSI TR 102 495-7: "Electromagnetic compatibility and Radio spectrum Matters (ERM); System Reference Document; Short Range Devices (SRD); Technical characteristics for SRD equipment using Ultra Wide Band Sensor technology (UWB); Part 7: Location tracking and sensor applications for automotive and transportation environments operating in the frequency bands from 3,1 GHz to 4,8 GHz and 6 GHz to 8,5 GHz". [i.6] The Association of the European Rail Industry (UNIFE). NOTE: Website: http://www.unife.org/. [i.7] CEPT/ECC Report 64: "The protection requirements of radiocommunications systems below 10,6 GHz from generic UWB applications", Helsinki, February 2005. [i.8] IEEE 802.15.4a: "Standard for Information Technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - specific requirement Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (LR-WPANs)". [i.9] ECC/REC(11)09: "UWB Location Tracking Systems Type 2 (LT2)". [i.10] ECC Report 167: "The Practical Implementation of registration/coordination mechanism for UWB LT2 systems". ETSI ETSI TR 101 538 V1.1.1 (2012-10) 8 [i.11] ECC/DEC (06)04: " The harmonised conditions for devices using UWB technology in bands below 10.6 GHz ". [i.12] ECC Report 170: "Specific UWB applications in the bands 3.4 - 4.8 GHz and 6 - 8.5 GHz Location Tracking Applications for Emergency Services (LAES), location tracking applications type 2 (LT2) and location tracking and sensor applications for automotive and transportation environments (LTA)". |
c099f70226392b092615be99cebbaaec | 101 538 | 3 Definitions, symbols and abbreviations | |
c099f70226392b092615be99cebbaaec | 101 538 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: activity factor: effective transmission time ratio, actual on-the-air time divided by active session time or actual on-the- air emission time within a given time window distance: Euclidean distance between two objects, i.e. real distance duty cycle: defined as the ratio, expressed as a percentage, of the transmitter "on" relative to a given time period as specified in the technical requirements fixed equipment: UWB location tracking device on a fixed position mobile equipment: UWB location tracking device to be used while in motion or during halts at specified points range: measured distance between two objects, i.e. erroneous distance range resolution: ability to resolve two targets at different range |
c099f70226392b092615be99cebbaaec | 101 538 | 3.2 Symbols | For the purposes of the present document, the following symbols apply: AF activity factor BW bandwidth c velocity of light in a vacuum dBm decibel relative to 1 mW ∆h Transmission interval ∆t Transmission on Ddata data rate δR range resolution or multipath rejection resolution r Range of UWB device Rdata ranging packet length Tp pulse width Ur Update rate |
c099f70226392b092615be99cebbaaec | 101 538 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: 3D Three Dimensional AF Activity Factor AFR Activity Factor Restriction AOI Area-Of-Interest BSS Board SubSystem CBT Communication-Based Train Control CBTC Communication-Based Train Control CEPT European Conference of Post and Telecommunications Administrations ETSI ETSI TR 101 538 V1.1.1 (2012-10) 9 CIS Commonwealth of Independent States CO2 Carbon Dioxide DAA Detect-And-Avoid DCR Duty Cycle Reduction e.i.r.p. Equivalent Isotropic Radiated Power ECC Electronic Communications Committee ETCS European Train Control System FS Fixed Service GSM-R Global System for Mobile Communications-Railways GSS Ground SubSystem LDC Low Duty Cycle LOS Line-Of-Sight MAC Medium Access NAFTA North American Free Trade Agreement NLOS Non-line-of-sight OBU OnBoard Unit PHY Physical POI Point-Of-Interest PSD Power Spectral Density QoS Quality-of-Service RX Receiver TDD Time Division Duplex TPC Transmission Power Control TX Transmitter UWB Ultra WideBand |
c099f70226392b092615be99cebbaaec | 101 538 | 4 Presentation of the system or technology | In a railway network, there are two important functions that rely on knowing the position and speed of the train. The first, and the oldest, is signalling and the control of the track. The second function is train control, which was once performed by the train driver alone. One important part of the train control function in urban railways is stopping the train in the right place at a platform, and if the platform has gates this requires centimetric accuracy and is always done automatically. This system can be used by other train-borne systems to sense the train's position along the railway. Using this system the onboard equipment will stop the train precisely. In fact these functions are real innovations because very often there are stringent requirements by customers in subways where good efficiency in difficult radio propagation environments (e.g. tunnels) has to be guaranteed. Currently the state-of-the-art to perform the train positioning includes inductive cables or railroad circuit to detect which is the block to be taken by the train and it is easy to understand that using these systems only low position accuracy is achievable. The conventional line signalling and illustration of braking train when approaching railway crossing are depicted in Figure 1. In here, the train is receiving information to stop from a wayside device, and the train is stopped by using, e.g. inductive cables as illustrated Figure 2. The OnBoard Unit (OBU) is a device installed in a train which takes care on communication between a train and wayside network. Figure 1 Figure 2 The heart of this proposed system is the ultra reaching good results for all the requirements high velocity of the train can be considered a wireless technologies to respond to these cha offers the best guarantees. Specialities for positioning application in rail • Cost-efficient • High velocity • The information of the train's physic • Track discrimination • High accuracy • Interference tolerant • Energy saving Railway environment can be divided in the fo 1) Subway and underground 2) Depot ETSI ETSI TR 101 5 10 : Conventional line side signalling 2: Conventional stopping of a train a-wideband radio that will introduce high-level performa s listed above. In fact, basically high accuracy positionin as the main challenge. It raises a concern on the ability o allenges. Based on this consideration, UWB is the techno lway environment are: cs (acceleration...) ollowing environments: 538 V1.1.1 (2012-10) ances and benefits, ng combined with of the current ology that currently ETSI ETSI TR 101 538 V1.1.1 (2012-10) 11 3) Ground Station or Railway station 4) Railway signal or Point-of-Interest (POI) along railroad Apart from some urban or local transit systems, a "railway" is a part of a very much large network, even on a national scale. And large cities may have multiple inter-working railways (notably in London). Even a new self-contained railway system is likely to include parts with different characteristics - for example some underground and some on the surface, station spacings varying greatly, or some on roads (for trams or light rail) and some on segregated tracks. While it is obviously an advantage to use one sensor type throughout, other considerations may determine that one (e.g. UWB) is only used in a part of the network. Also, different parts of the network may be different environments as far as radio regulations are concerned. The clearest case of this is where part of the network is underground or enclosed (hence "indoors", though this word might seem a little odd for a large railway station) and part is in the open. |
c099f70226392b092615be99cebbaaec | 101 538 | 4.1 Subway and underground | The subway represents a classic indoor use scenario for railway applications of UWB. Typically, subway trains are operating under the ground and stations are located also under the ground as presented in Figure 3. Installation of devices in the subway environment is illustrated in Figure 4 where UWB transmitter (BSS, Board SubSystem) is installed in a train and UWB receivers (GSS, Ground SubSystem) are mounted in the ceiling. In the subway environment, there are structures that block or attenuate an emitted signal, and thus does not interfere other radio systems. The operating time varies from 20 h to 24 h per day in large and congested subway stations, and operating frequency is handling 20 to 60 trains per hour. Figure 3: Typical subway station Figure |
c099f70226392b092615be99cebbaaec | 101 538 | 4.2 Depot | The railway depot is an area for maintenance wide and open shed where the walls of the sh 4.3 Ground Station or An uncovered railway station represents a go does the ground tram station shown in Figure necessary attenuation of an emitted signal to communications, and there may be many suc country. Therefore, mitigation techniques to g studied. In typical railway station, the operating frequ The railway waysides are authorized areas an ETSI ETSI TR 101 5 12 e 4: Installation of UWB devices e and storage of trains in, for example, an indoor environ hed attenuate an emitted signal. r railway station ood example of an outdoor railway scenario as illustrated e 6. In these scenarios, there are not always shielding str protect other radio systems such as Fixed Service (FS) o ch installations across a public rail network covering (for give enough protection for other radio systems are need uency is 10 to 20 trains per hour 24 hours per day. nd are restricted from unauthorized persons' presence. 538 V1.1.1 (2012-10) nment such as a d in Figure 5, as ructures providing or satellite r example) a city or ded to be carefully ETSI ETSI TR 101 538 V1.1.1 (2012-10) 13 Figure 5: Typical railway station Figure 6: Typical ground tram station ETSI ETSI TR 101 538 V1.1.1 (2012-10) 14 |
c099f70226392b092615be99cebbaaec | 101 538 | 4.4 Railway signals or POI along railroad | A railway signal (see Figure 7) is an electrical device installed along a track to pass information relating the state of the line ahead to a train. A generic Point-of-Interest can be a stopping point in a loading platform for instance. It is important to stop a train accurately so that there is no need to relocate a train for loading. Again, these situations represent largely outdoor use of UWB, and there may be significant numbers of signals across a public rail or tram network. Figure 7: Typical railway signal |
c099f70226392b092615be99cebbaaec | 101 538 | 5 Radio spectrum regulations and compliance | |
c099f70226392b092615be99cebbaaec | 101 538 | 5.1 Technical justification for spectrum | |
c099f70226392b092615be99cebbaaec | 101 538 | 5.1.1 Technical justification for power levels | UWB positioning can only make use of a fraction of the energy emitted by a UWB transmitter: that portion which reaches a receiver via the direct path. Only the signal travelling along this path conveys information about the location of the transmitter relative to the receiver. This is in contrast to communications systems, which may utilize signals travelling along any or all paths between the transmitter and receiver (e.g. systems involving rake receivers). The UWB system under consideration operates (depending on target scenario) either in the 3,1 GHz to 4,8 GHz or in the 6 GHz to 8,5 GHz frequency region and is mainly operating under the Line-Of-Sight (LOS) conditions, and thus a maximum PSD limit of -41,3 dBm/MHz, as defined in ECC/DEC(06)04 [i.1] recently amended in [i.11], is enough for the applications described in the present document. It is worth to distinguish between very short range (<10 meters) applications and short range ones (up to 50 m). Indeed, after the definition of "exterior limit" [i.11], several UWB emitters maybe installed "on board" the train cars, provided that the proposed "PSD exterior limits" (-53,3 dBm/MHz) are satisfied by each of these mobile UWB emitters, operating either in the frequency band from 3,1 GHz to 4,8 GHz and in the higher band from 6 GHz to 8,5 GHz. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 15 This deployment of multiple UWB emitters on-board, transmitting outwards the train cars, is free of limitations (with the duly exception of the said "PSD exterior limits" [i.11] and activity factor LDC <5 %) as, in other words, devices registration is not required and they may be coupled with a suitable number of "ground-based" wayside receiving devices, deployed in the frame of a purely "passive" fixed infrastructure, in such a way that tracking accuracy is enhanced, together with availability and reliability. Graceful increase of railway signalling system availability/reliability maybe proportioned to the actual multiplicity of such "mobile" UWB emitters and of the corresponding "ground-based" receivers installed at fixed reference points belonging to the wayside infrastructure. Dealing with tracking operation at increased ranges, up to ≈50 meters, the system operation should cope with several critical factors which may impair the tracking availability and accuracy wayside, unless provision of appropriate countermeasure is adopted in terms of power level and of other design provisions. As experienced in real installation, the following list of critical factors is provided as an exemplary, but not limitative, description of main technical challenges, associated with the operation of short-range low-power UWB tracking systems in railway environment. Technical descriptions are provided in annex B, including system architectures and corresponding link budgets, shown in the following clause B.3. Table 1: Critical factors limiting the performance of UWB systems in railway environment Frequency (GHz) Area of Operation Critical factors impairing system performance Countermeasures compatible with limits and ECC regulations 3,11 < f < 4,8 PSD <-53,3 dBm/MHz for unregistered UWB unlicensed mobile devices with 5 % activity LDC PSD <-41,3 dBm/MHz for registered devices very short range (<10 meters) short range (<50 meters) Multipath Broadband interferers (e.g. automotive UWB) Multipath + path loss Broadband interferers Multiple UWB emitters onboard the train cars real-time processing Multiple "ground-based" fixed receivers Multiple UWB emitters at 3,1 GHz to 4,8 GHz deployed as "ground- based" fixed references for real-time processing 6 < f ≤ 8,5 PSD <-53,3 dBm/MHz for unregistered UWB mobile devices with 5 % LDC very short range (<10 meters) Multipath Multiple UWB emitters onboard the train cars real-time processing Narrow-beam antenna NOTE: At highest frequencies (6 < f ≤ 8,5 GHz) very short-range (<10 meters) applications only are affordable, due to the fact that fixed infrastructures made of UWB emitters are not allowed by ECC. It is easy to demonstrate that, either onboard and in the fixed infrastructures, the adoption of multiple UWB emitters improves the system performance and maximises its availability for tracking ranges extending up to 50 meters and over. On the other hand, the most recent ECC recommendation [i.9], aiming the protection of existing services, dictates that each UWB emitter belonging to fixed infrastructure is limited to an average PSD of -41,3 dBm/MHz e.i.r.p. in the lower frequency band only, that is from 3,4 GHz to 4,2 GHz, and maybe extended from 4,2 GHz to 4,8 GHz, when complying with tighter limit of -47,3 dBm/MHz in the higher portion of this lower band. Moreover, a registration/coordination process should be undertaken, in charge of national authorities, according to the proposed guidelines given by ECC Report 167 [i.10] and ECC Report 170 [i.12]. Therefore, the perspective of using UWB devices in railway tracking applications, extending up to 50 meters and over, appears less favourable and much less affordable than tracking for just shortest ranges (<10 meters), due to the combined effect of four critical factors: multipath, path loss, PSD/band limitations and registration/coordination mechanism. It is clear that UWB devices afford advantages over other wireless technologies particularly in the very short-range applications, where they maybe suited for widespread "unregistered" use, provided that each UWB emitter installed onboard the train cars complies with the tightest PSD "exterior limit" of -53,3 dBm/MHz, as ECC recently stated [i.11]. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 16 |
c099f70226392b092615be99cebbaaec | 101 538 | 5.1.2 Technical justification for bandwidth | The accuracy of radio ranging location devices is determined by the occupied bandwidth of the signal, provided it is processed coherently. For example, in a pulse-based system, if the device has to reliably measure different transmitter- receiver ranges when the transmitter is moved from one point to another, the difference in the travel time of the signal from the transmitter to the receiver at the two different positions should be greater than the pulse width. Similarly, a direct path signal and a reflected multipath signal can be separated if the extra time interval required for the signal to travel the reflected path rather than the direct path is greater than the pulse width. The bandwidth required to provide the same resolution as a pulse of width TP is approximately 1/TP. Therefore, for a range resolution or multipath rejection resolution of δR, the bandwidth requirement for the UWB location tracking devices is given by: = (), where c is the velocity of light in a vacuum. For a range resolution of 10 cm, this gives a bandwidth requirement of around 3 GHz. For a measurement accuracy of 10 cm, the resolution can be somewhat larger, so that a bandwidth of 1 GHz to 1,5 GHz can be enough. |
c099f70226392b092615be99cebbaaec | 101 538 | 5.2 Compliance to current regulations | The radio regulations for indoor environments, i.e. subway, underground, and depot as discussed in clauses 4.1 and 4.2 are included in amended ECC/DEC(06)04 [i.11] excluding fixed outdoor location tracking installations as shown in Table 2. Table 2: Current regulations (excluding fixed outdoor installations) for UWB systems Frequency (GHz) Area of Operation Maximum value of mean power spectral density [dBm/MHz] 3.1 < f < 4.8 6 < f ≤ 8.5 generic usage in train vehicles < -41.3 (exterior limit -53.3) (assuming implementation of LDC mitigation as stated in ECC/DEC/(06)04 [i.11]) 3.1 < f < 4.8 6 < f ≤ 8.5 train vehicles in underground and indoor environment < -41.3 (exterior limit of -53.3 over 0 o not necessary, see ECC report 170 [i.12]) NOTE: No active UWB outdoor transmitter; Base stations outdoor are passive, all active UWB transmitters are onboard train vehicles. |
c099f70226392b092615be99cebbaaec | 101 538 | 5.3 Additional compliance to ECC recommendation | A railway network will usually have some parts that qualify as "indoor" for UWB regulations, and some that are "outdoor". However, the same UWB terminals may need to operate in both. Not only will terminals on trains move between such environments, but fixed terminals throughout the network will need to operate with low activity factor, just in case these mobile terminals come around. In addition, within the network there will be a few places with many trains and lines, most of the network will have a much lower density. The ECC recommendation [i.9] has proposed limits for type 2 location tracking UWB fixed emitters applications in the frequency range 3,4 GHz to 4,8 GHz as shown in Table 3. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 17 Table 3: Current ECC recommendation [i.9] for LT2 applications Frequency GHz Maximum value of mean power spectral density [dBm/MHz] 3,4 < f < 4,8 ≤ -41,3 dBm/MHz fixed outdoor subject to implementation of DCR and subject to some coordination/registration [i.10] for licensing. the maximum mean e.i.r.p. spectral density in the band 4,2 GHz to 4,4 GHz for emissions that appear 30° or greater above the horizontal plane should be less than -47,3 dBm/MHz. It is worth to underline that coordination/registration process [i.10] allows UWB devices deployment at fixed outdoor locations (with PSD limit of -41,3 dBm/MHz or -47,3 dBm/MHz), according to [i.9] as LT2 tracking network "registered" infrastructure, only in the lower band from 3,4 GHz to 4,8 GHz. The main benefit of such deployment of UWB emitters at fixed outdoor locations would be to make more appealing and more affordable LT2 railway applications also for tracking range up to 50 meters and over. |
c099f70226392b092615be99cebbaaec | 101 538 | 5.4 Summary UWB regulation for specific railway application | Table 4: Summary / Interpretation of existing UWB regulation for this specific UWB railway applications Frequency (GHz) Area of Operation System license type Maximum value of mean power spectral density [dBm/MHz] 3,1 ≤ f ≤ 4,8 6 ≤ f ≤ 8,5 (Note 1) generic usage in train vehicles Unregistered system, licence exempt usage ≤ -41,3 (exterior limit -53,3) (assuming implementation of LDC mitigation as stated in ECC/DEC/(06)04 [i.11]) 3,1 ≤ f ≤ 4,8 (Note 2) train vehicles in underground and indoor environment, (Note 3) Unregistered system, licence exempt usage ≤ -41,3 (exterior limit of -53,3 over 0º not necessary, see ECC report 170 [i.12] (assuming implementation of LDC mitigation as stated in ECC/DEC/(06)04 [i.11]) 6 ≤ f ≤ 8,5 (Note 2) train vehicles in underground and indoor environment, (Note 3) Unregistered system, licence exempt usage ≤ -41,3 (exterior limit of -53,3 over 0º not necessary, see ECC report 170 [i.12] 3,4 ≤ f ≤ 4,8 train vehicles Registered systems [i.10] ≤ -41,3 (Note 4) 3,4 ≤ f ≤ 4,8 outdoor fixed UWB transmitters Registered systems [i.10] ≤ -41,3 dBm/MHz fixed outdoor subject to implementation of DCR and subject to some coordination/registration [i.10] for licensing (Note 5) NOTE 1: No active UWB outdoor transmitter; Base stations outdoor are passive, all active UWB transmitters are onboard train vehicles. NOTE 2: UWB transmitters in the indoor environment can be seen as an device under the Generic UWB rules [i.11], chapter 1. NOTE 3: For more details clauses 4.1 and 4.2. NOTE 4: A maximum duty cycle of 5 % per transmitter per second and a maximum Ton = 25 ms apply. The duty cycle should also be limited to 1,5 % per minute or equipment should implement an alternative mitigation technique that provides at least equivalent protection [i.9]. NOTE 5: The maximum mean e.i.r.p. spectral density in the band 4,2 GHz to 4,4 GHz for emissions that appear 30° or greater above the horizontal plane should be less than -47,3 dBm/MHz [i.9]. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 18 Annex A: Detailed market information The proposed specific application using the UWB technology in railway application will play an important rule into the worldwide railway market. This clause shows how this wireless technology matches the requirements defined for this growing market. The following considerations were given by [i.6]. The worldwide rail market has grown tremendously in the past few years and the expectations for the next ten years is to have several new railway projects around the world for upgrading and expanding existing railway lines. The railway market environment changes in the short time frame and the rail suppliers should adapt their products and services developing new technologies. In this way, they are able to support passenger's mobility needs and cargo transport. In this scenario, innovations make rail transport more attractive adding high technological value. The market rail could be divided into: • Rail Control • Infrastructure • Rolling Stock • Services Total M arket Accessible M arket Figure A.1: Average annual market volumes in the last few years Figure A.1 shows the annual average market volumes and how it is distributed, moreover it describes which is the "accessible market" opened to external suppliers. In the last years this market has grown and this trend will be maintained with an expected annual growth till 2,5 % in the seven years reaching a volume of EUR 160 billion of which EUR 115 billion will be accessible (71,8 %). ETSI ETSI TR 101 538 V1.1.1 (2012-10) 19 Figure A.2: World segmentation Reading Table A.1, the most important markets are: Europe, NAFTA and ASIA/Pacific region but with the expected dynamic growth, Asia/Pacific will surpass NAFTA in the next six years. On the other hand, the marketing forecast shows also that the growth in NAFTA will continue but below the world average. The estimated rail market for the last years listed in Table A.1 has focused on 50 countries that include 95 % of the whole global rail market. Table A.1: Distribution of Accessible market in the world in the last years Rail Market % (EUR bn) W. Europe 33 E. Europe 5 CIS 12 NAFTA 20 Rest of America 3 Asia / Pacific 25 Africa / Mid. East 2 Rail suppliers are companies that manufacture rail infrastructure, rolling stocks and rail signals. Besides these are multinational companies that spread over thousands of suppliers and sub-suppliers. The telecommunications systems are key part of these complex systems and the introduction of new technologies in this field pulls the railway products making these more attractive. In the medium and long term period, the rail industry follows new trends reported below: • Ecological awareness • Resources scarcity • Urbanization • Competition with other modes of transport • Standardization The companies answer to these treats developing new products where (for example): 1) emissions are reduced (CO2 emissions limits, noise control, electromagnetic pollution reduction); 2) transport capacity is increased; 3) efficient rolling stocks are developed; 4) standardization activates are included. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 20 Besides, the competition with other modes of transport will push rail companies to fulfill new requirements to cut the travel times providing more traveller benefits. Figure A.3: Development of the world total rail market. In Figure A.3, the development of the total rail market during the next 6 years is presented, and the Rail Control segment is underlined because in Europe it will be one of the most important, followed by Asia/Pacific area. Rail Control is the market where the telecommunications play as top-tier player because railway signalling solutions (interlocking, trackside products, etc.), train protection (CBTC - Communication-Based Train Control, ETCS - European Train Control System, etc.), rail telecommunication and station operation systems are included. Starting from all the previous considerations, ultra-wideband technology gives a fundamental contribution in the development of new rail systems because it matches many key requirements listed in the present document. Using UWB in railway could increase the train positioning accuracy, giving on the other hand the chance to increase the transport capacity in subways and light rail transit systems. This benefit could be amplified by the huge number of new metro and light rail systems expected to build in Europe and Asia (urbanization). The innovation introduced by wideband wireless communication will make rail systems more efficient and create an infrastructure for sustainable transportation, which is essential for economic growth, prosperity and increased safety. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 21 Annex B: Detailed technical, density and activity information B.1 Detailed technical description The following description covers a range of possible system architectures, so as to be technology neutral. However, the detailed parameters and calculations in the present document relate to only one specific case. A tracking system of presented application can be realized in three different ways: • Using transmitter which is installed into a rail vehicle and fixed receiving wayside equipment (option 1, see Figure B.1). The UWB signals emitted by a transmitter installed in a moving rail vehicle are detected by a wayside network of receivers which are fixed equipment placed at known, fixed points around the area to be covered. By centralized computational means, the location of a rail vehicle can be determined. This is a typical application. • Using receiver which is installed into a rail vehicle and fixed transmitting wayside equipment (option 2, see Figure B.2). The UWB signals emitted by a wayside network of transmitting fixed equipment placed at known, fixed points around the area to be covered are detected by receiving equipments installed in a moving rail vehicle detecting their own position. • Using transmitter/receiver which are installed into a rail vehicle and fixed transmitting/receiving wayside equipment (option 3, see Figure B.3). A combination of options 1 and 2; both units are installed in a rail vehicle and the fixed wayside equipment can receive and transmit UWB-signals. Table B.1: Options for implementation of location tracking system Option Vehicle Wayside 1 TX RX 2 RX TX 3 TX/RX TX/RX For option 1, the location tracking system of a train can be realized as illustrated in Figure B.1, where UWB transmitter (TX) is installed in a moving train. An emitted UWB signal is detected by a network of fixed UWB receivers (RX) placed at known, fixed points around the area to be covered. Each UWB RX transmits its information to rest of the network for further processing, where the position of a train is computed in centralized fashion. The 3D position of an UWB TX can be calculated by detecting an emitted signal at a number of receivers and analysing the time-of-arrival or/and angle-of-arrival of the emitted signal at each receiver. Since trains only run on tracks, full 3D positioning is not always needed. If it is not, then fewer terminals are needed at each position along the track - in some architectures only one. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 22 Figure B.1: Components of a UWB location tracking system (option 1) In option 2, the location tracking system applies transmitting fixed wayside network, and position is calculated in the receiver installed in a moving rail vehicle as shown in Figure B.2. Position information can be transmitted to a backbone network by using, e.g. Global System for Mobile Communications-Railways (GSM-R). Figure B.2: Components of a UWB location tracking system (option 2) ETSI ETSI TR 101 538 V1.1.1 (2012-10) 23 Option 3 describes the systems where a UWB TX/RX is installed in a moving rail vehicle and fixed wayside network includes in UWB TX/RX nodes as shown in Figure B.3. In this option the position information can be calculated: a) in a rail vehicle and sent back to a backbone network by using UWB; b) in a rail vehicle and sent back to a backbone network by using, e.g. GSM-R; c) in a system and sent back to a rail vehicle by using UWB if needed; d) in a system and a rail vehicle and then the information can be compared. Figure B.3: Components of a UWB location tracking system (option 3) A train transmits packets only within an area-of-interest (AOI) around a point-of-interest (POI), which can be, e.g. a signal device. The concept of AOI and POI is illustrated in Figure B.4. AOI is the area along a track having a length enough to stop a train to POI. Typically, AOI might be hundreds of meters long along a track. A system tracks a train within AOI to stop a train in POI with sub-meter accuracy. When a train is stopped to POI, transmission is interrupted until a train goes on, and transmission is switched on again. Tracking of a train is needed after POI to ensure that a train is in correct track. The control of signalling of a railway system is done by a railway operator. Therefore, this application is designed for private use, and system usage is very controlled. Because UWB transmission occurs only within AOI, this application is highly site-specific. Moreover, the rail tracks are restricted areas where unauthorised being is forbidden. Due to the path loss, the low power transmitted UWB signal attenuates before being in a location of other spectrum users. The movement of a train is also averaging out the impact of UWB signal on a certain fixed point around a train track. Generally speaking, AOI can be expanded to cover a complete urban/suburban railway network where a train is tracked continuously but this should not be considered as a main application described in the present document. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 24 Figure B.4: Area-of-Interest of a UWB location tracking system In Figure B.5, a scenario where two trains are present is depicted. This illustrates the situation, e.g. in a small railway station. There are three POIs in the system; the point where train #2 can change a track (POI #2) and stopping points POI #1 and POI #3. All of these have their own AOIs. But as it can be seen, these AOIs overlap with each other, and therefore some of the receivers can be applied in several AOIs. Figure B.5: Case of multiple users ETSI ETSI TR 101 538 V1.1.1 (2012-10) 25 B.2 Density and activity B.2.1 Density of UWB transmitters UWB device densities and activity factors for the application are considered in point of view of different options described in Table B.1, and a point of view of different scenarios described in the following: Scenarios are divided for three cases by the width of the service area (Area where positioning application is needed) from the point of view investigated area of 1 km2. Case A) Width > 1 km This case covers situations where the region where positioning is needed covers an extended outdoor area, i.e. locations where many tracks run parallel to each other. Examples might be areas in and around railway stations or entering train depots. Case B) Width <1 km This case covers situations where the area where positioning is needed is limited to a more restricted area, for example wayside areas with Point-Of-Interest (POI). These might occur on the railroad network between railroad stations and/or train depots, with POI or POIs where the accurate position is needed. Typically length of this area is ±300 m and width is ±10 m from the POI. Case C) Wayside area without POI Railroad network between railroad stations and/or train depots, without POI, in other words, area of railroad network where the accurate position is not needed. The service of the positioning application is not needed, and so on all the UWB transmitters are not active. Here, the activity factor will be 0 % and there's no purpose to go on with analysis within Case C) assumptions. These three cases are illustrated in Figure B.6. It should be noted that Figure B.6 is not any mean in scale or not giving correct example about the application (i.e. number of tracks is only for illustrative purposes only). Figure B.6: Railroad network from the point of view the Positioning Application Cases A, B, and C are presented in more details in Figure B.8, Figure B.9 and Figure B.10 and corresponding legend are shown in Figure B.7. Figure B.7: Symbols and legend for the Case A, B and C ETSI ETSI TR 101 538 V1.1.1 (2012-10) 26 Case A) Case A) is illustrated in Figure B.8. Length of the service area is more than 1 km, and width of the service area depends on number of parallel tracks. Figure B.8: Illustration of Case A) In railroad station or train depot entrance area, the worst case scenario can be described with 40 parallel track (e.g. Gare du Nord, Paris with 44 platforms, although 2 tracks are not in use and 14 are for suburban) and train using positioning application at each track. Same worst case assumption holds for the typical train depot area. The following calculations are carried out also with 20 parallel tracks to give an example about scalability. Distance between each pair of the 40 tracks are assumed to be 4,0 m, making width of the area 160,0 m, and 80,0 m respectively for 20 tracks. Range for the UWB devices is assumed to be 25 m (commercially available, NLOS case). For the positioning application it is required to cover each point of the area several times, i.e. in case of 3D-positioning minimum of 4 reference points (anchors) are required. We derive required number of devices as a function of UWB range (r) as # = 4 ∙ ∗ ² Additionally, the train has at most two active devices at the time. The following estimates are done by assuming two devices active for each train being the worst case scenario. To cover breakdowns it is possible that two or more devices are installed at the train end parallel, but only 1 is active at the time. Table B.2 presents maximum amount of UWB transmitters per km2 with assumption of 40 parallel tracks and respectively Table B.3 with 20 parallel tracks. To have redundancy it is assumed to have 25 % more devices than minimum requirement for the positioning application is. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 27 Table B.2: Transmitter densities for Case A) with 40 parallel tracks per km2 Option Number of transmitters at Trains Number of transmitters at Wayside Total 1 80 0 80 2 0 326 + 25 % 408 3 80 326 + 25 % 488 3* 160 326 486 Option 3* shows an alternative solution having 4 transmitters active at one train to achieve redundancy for the quality- of-service (QoS) required by the positioning application. It shows that number of UWB transmitters in worst case scenario is still same on average. Table B.3: Transmitter densities for Case A) with 20 parallel tracks per km2 Option Number of transmitters at Trains Number of transmitters at Wayside Total 1 40 0 40 2 0 163 + 25 % 203 3 40 163 + 25 % 243 3* 80 163 243 Case B) Case B) is illustrated in Figure B.9. Length of the service area is less than 1 km so only a portion of area covered by UWB transmitters covers the 1 km2. Case B) Area with POI x = Area length y = Area width Figure B.9: Illustration of Case B) Service area outside a station or a train depot usually has not more than 4 railroad tracks, making the width of the area narrow, but not narrower than UWB RX range. Estimate for the UWB TX density can be derived as a following: # = 4 ⋅600 ∗25 ETSI ETSI TR 101 538 V1.1.1 (2012-10) 28 Estimates with UWB TX range r = 25 m is illustrated in Table B.4. For redundancy 25 % more devices are taken into account as in previous case. Table B.4: Transmitter densities for Case B) per km2 Option Number of transmitters at Trains Number of transmitters at Wayside Total 1 8 0 8 2 0 31 + 25 % 39 3 8 31 + 25 % 47 Case C) Case C) is illustrated in Figure B.10. Case C) is the area where no position application is needed. This is presented for illustrative purposes only since several kilometres of railroad network is area of no need for high accuracy positioning service - some non-UWB service can be applied. Case C) Area without POI Figure B.10: Illustration of Case C) Although in this discussion concentrating for the worst case scenarios, we rule out Case C), and consider that there exists on the average 1 POI / km. B.2.2 Activity Factor Duty cycle has been ruled out from the following consideration of activity factor as stated in [i.7]: "The activity factor reflects the effective transmission time ratio. It does not take into account reduction factors such as time division duplex (TDD) and pulse duty cycle." Activity factor is defined in the presented document as effective transmission time ratio, actual on-the-air time divided by active session time or actual on-the-air emission time within a given time window. The derivation for the Activity Factor of single UWB transmitter is illustrated in Figure B.11 and is formalized as following: = ∙ ∙ , ETSI ETSI TR 101 538 V1.1.1 (2012-10) 29 where Rdata is ranging packet length and Drate is data rate (i.e. 0,85 Mbps from IEEE 802.15.4a [i.8]), and service time per time window is ratio which service is on, i.e. time that transmitter is on. Service window @ velocity v Train Train #1 Train #2 Train #n ... ∆t ∆h 1 hour time window Service ON Service ON Service ON Service OFF Service OFF Figure B.11: Activity Factor Figure B.11 presents the following parameters: Transmission on = ∆ = ℎ = , and Transmission interval = ∆ℎ= 1 = 1 . From transmission time and transmission interval duty cycle can be derived as a following: Duty cycle = ∆ ∆ℎ= ∗ . This result is averaged over an (peak) hour, where ratio of service time per peak hour is defined as: !" "# $"# %"&% = % over 1 hour. Estimating Rdata length as maximum of 2 kbit (to cover synchronization header, physical layer header, and data), and assuming that required quality of service for the positioning application can be achieved with 4 ranging messages having guard interval length of one message gives as factor of 7. With update rate of 10 Hz, derivations for the activity factor are presented in Table B.5. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 30 Table B.5: Activity Factors within 1 hour peak time window Case Trains per hour Speed Service Time (% per hour) AF (η) Light Transit 20 140 km/h 14 % 0,024 % Light Transit 20 60 km/h 33 % 0,056 % Light Transit 20 140 km/h 0 km/h 140 km/h (see note) 91 % 0,15 % Subway 60 110 km/h 55 % 0,093 % Subway 60 60 km/h 100 % 0,17 % Subway 60 60 km/h ≥ 0 km/h ≥ 60 km/h 100 % 0,17 % 1 0 km/h 100 % 0,17 % NOTE: Train stands 1 min at the station. It should be noted that Table B.5 presents activity factors for one transmitter. Number of transmitters and density of transmitters are matter of scenario. Table B.6 and Table B.7 present the densities of active UWB transmitters for Case A and Case B, respectively. Table B.6: Density of active UWB transmitters per km2 for Case A Case A Option 1 Option 2 Option 3 Option 3* UWB density (/km²) 80 408 488 486 Activity factor (η) 0,2 % 0,2 % 0,2 % 0,2 % Density of active UWB transmitters (/km²) 16 82 98 98 Table B.7: Density of active UWB transmitters per km2 for Case B Case B Option 1 Option 2 Option 3 UWB density (/km²) 8 39 47 Activity factor (η) 0,2 % 0,2 % 0,2 % Density of active UWB transmitters (/km²) 2 8 10 B.3 Technical parameters and implications on spectrum B.3.1 Transmitter parameters B.3.1.1 Transmitter Output Power / Radiated Power The transmission masks are compliant with the last amendment [i.11] of ECC/DEC(06)04 and, solely for deployment of UWB emitters at fixed outdoor locations, with ECC/REC(11)09 [i.9]. B.3.1.1a Antenna Characteristics For location tracking application, such as this system, omni-directional antennas are needed to cover wide area of interest. Low antenna gains may be used, if applicable to radiated power as defined by clause B.3.2.1. However, directional antennas may be used to reduce interference to/ from some direction. If directional antennas are applied the limits radiated power should be met as defined by clause B.3.2.1. The use of directional antennas are recommended to use in outdoor environment to reduce interference to fixed service systems. B.3.1.2 Operating Frequenc There are two possible operating frequencies on the target scenario and environment: 3,1 G range is more favourable by providing more b lower band is more attractive due to the avail also because of the lower propagation losses. tracking ranges up to 50 meters and over by m locations wayside, according to the provision described in [i.10]. Tuneable frequency transmitters allow flexib mechanism required for LT2 emissions at hig B.3.1.3 Bandwidth The necessary bandwidth of 2 GHz is needed bandwidth is 2,5 GHz in the 6 GHz to 8,5 GH In the lower band from 3,1 GHz to 4,8 GHz, yielding to 18 cm resolution. B.3.2 Receiver paramet Receiver should have such characteristics tha Receiver architecture include at least an ante a digital correlator/demodulator which feeds ranging and for communication packet decod ETSI ETSI TR 101 5 31 cy for the application to be operated using onboard UWB GHz to 4,8 GHz and 6 GHz to 8,5 GHz. From these, the bandwidth, and thus, better time resolution. But on the o lability of chipsets having lower costs and higher antenn . Moreover, in the lower band there is the possibility of a means of the deployment of multiple UWB emitters at f ns of ECC/REC(11)09 [i.9] and with the registration/coo bility in Frequency allocation, according to the registratio ghest power for tracking distances extended up to 50 me Figure B.12 d to gain 15 cm resolution, whereas the maximum possib Hz band. all the bandwidth is needed to gain as a good range reso ters at ranging can be done with high reliability. Figure B.13 enna, a low-noise amplifier, followed by a downconvert the received raw data to the real-time algorithms neede ding. 538 V1.1.1 (2012-10) emitters, depending upper frequency other hand, the na efficiency but achieving extended fixed outdoor ordination process on/coordination eters and over: ble occupied olution as possible ter-to-baseband, and d either for accurate ETSI ETSI TR 101 538 V1.1.1 (2012-10) 32 Figure B.14 Typical Link Budget, here below estimated for the most favourable Line-of-Sight (LOS) propagation, clearly shows that accurate and reliable ranging/tracking at distance of 50 meters definitely requires Option 3 system configuration, where a UWB TX/RX is installed in a moving rail vehicle and fixed wayside network includes UWB TX/RX nodes as previously depicted in Figure B.3. The assumed link budget formula is: Pr = Pt + Gt + Gr - Lf - Ld where: - power received at the receiver input port Pr = - 79.5 dBm - power transmittable according to PSD = -41.3 dBm/MHz Pt = -10 dBm - transmitting antenna gain Gt = 0 dBi - receiving antenna gain Gr = 10 dBi - free space path loss [ 20 Log(4π f / 3.108)] f = 4.5 GHz Lf = 45.5 dB - loss due to the distance of 50 meters [ 20 Log (50) ] Ld = 34 dB Average noise power per bit: No = 10 Log (Dr) + KTb + F + I = -106 dBm where: - assumed communication peak Data Rate of 1 Mbps 10 Log( Dr) = 60 dB - Boltzman constant by temperature of 300 °K KTb = -174 dB - assumed Noise Figure of the receiver F = 7 dB - assumed implementation loss I = 1 dB Assuming a receiver sensitivity of -80 dBm we finally get: Eb/No = 26 dB ETSI ETSI TR 101 538 V1.1.1 (2012-10) 33 B.3.3 Channel access parameters Density of devices is discussed in clause B.2.1. Duty cycle for the presented applications is defined in clause B.2.2. For typical application (option 1), the ALOHA medium access control (MAC) scheme as defined in [i.8] is proposed to be applied. In the ALOHA protocol, a UWB TX installed in a rail vehicle transmits whenever it is needed without sensing the medium or waiting for a specific timeslot. A UWB TX cannot wait a specific time slot or content the medium to transmit a ranging packet because of the high velocity of a vehicle. The ALOHA is appropriate for the typical application (option 1) because of lightly loaded network, i.e. up to 40 UWB-TXs as discussed in clause B.2. ETSI ETSI TR 101 538 V1.1.1 (2012-10) 34 History Document history V1.1.1 October 2012 Publication |
517a52b828a3794ba841b8ecef541827 | 101 537 | 1 Scope | The present document describes a series of tests that were undertaken to determine the parameters necessary to permit RFID to share the band 918 MHz to 921 MHz with ER-GSM. The tests were undertaken at the BNetzA Test Laboratory at Kolberg. The main purpose of these tests was to find answers to a number of important questions that had been raised during some earlier tests and to gather additional information. |
517a52b828a3794ba841b8ecef541827 | 101 537 | 2 References | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the reference document (including any amendments) applies. Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. |
517a52b828a3794ba841b8ecef541827 | 101 537 | 2.1 Normative references | The following referenced documents are necessary for the application of the present document. Not applicable. |
517a52b828a3794ba841b8ecef541827 | 101 537 | 2.2 Informative references | The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area. [i.1] ETSI EN 302 208 (V1.2.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM); Radio Frequency Identification Equipment operating in the band 865 MHz to 868 MHz with power levels up to 2 W". |
517a52b828a3794ba841b8ecef541827 | 101 537 | 3 Definitions, symbols and abbreviations | |
517a52b828a3794ba841b8ecef541827 | 101 537 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: Cognitive Radio System (CRS): Radio system (optionally including multiple entities and network elements), which has the following capabilities: • to obtain the knowledge of radio operational environment and established policies and to monitor usage patterns and users' needs; • to dynamically, autonomously and whenever possible adjust its operational parameters and protocols according to this knowledge in order to achieve predefined objectives, e.g. minimize a loss in performance or increase spectrum efficiency; and to learn from the results of its actions in order to further improve its performance. ETSI ETSI TR 101 537 V1.1.1 (2011-02) 6 Detect And Avoid: (DAA): technology used to protect radio communication services by avoiding co-channel operation NOTE: Before transmitting, a system should sense the channel within its operative bandwidth in order to detect the possible presence of other systems. If another system is detected, the first system should avoid transmission until the detected system disappears. DownLink (DL): direction from a hierarchic higher network element to the one below, in the case of a typical RFID system direction from the interrogator to tag or from the (E)R-GSM Base Transceive Station (BTS) to the terminal Dynamic Frequency Allocation (DFA): protocol that allows for changing transmit frequency during operation Dynamic Power Control (DPC): capability that enables the transmitter output power of a device to be adjusted during operation in accordance with its link budget requirements or other conditions fixed: physically fixed, non- moving device; includes temporary event installations as well link adaptation: result of applying all of the control mechanisms used in Radio Resource Management to optimize the performance of the radio link Listen before Talk (LBT): spectrum access protocol requiring a cognitive radio to perform spectrum sensing before transmitting location awareness: capability that allows a device to determine its location to a defined level of precision master: controls the radio resource changing actions mobile: physically moving device Radio Environment Map (REM): integrated multi-domain database that characterises the radio environment in which a cognitive radio system finds itself NOTE: It may contain geographical information, available radio communication services, spectral regulations and policies, and the positions and activities of co-located radios. Service Level Agreement (SLA): defined level of service agreed between the contractor and the service provider slave: responds to the commands from the Master UpLink (UL): Direction from Slave to Master white space: label indicating a part of the spectrum, which is available for a radio communication application at a given time in a given geographical area on a non-interfering/non-protected basis with regard to other services with a higher priority on a national basis |
517a52b828a3794ba841b8ecef541827 | 101 537 | 3.2 Symbols | For the purposes of the present document, the following symbols apply: α Pathloss Exponent in the Friis Equation dB decibel d distance f frequency measured under normal test conditions fc centre frequency of carrier transmitted by interrogator λ wavelength |
517a52b828a3794ba841b8ecef541827 | 101 537 | 3.3 Abbreviations | For the purposes of the present document, the following abbreviations apply: BCCH Broadcast Control CHannel BP BandPass BTS Base Transceive Station C/I Carrier to Interference ratio CMU Central Management Unit ETSI ETSI TR 101 537 V1.1.1 (2011-02) 7 DAA Detect And Avoid DFA Dynamic Frequency Allocation DL DownLink DPC Dynamic Power Control ER-GSM Extended R-GSM system FFT Fast Fourier Transform GSM Global System for Mobile communication IM3 third order intermodulation LBT Listen before Talk POS Point Of Sale R&S Rohde&Schwarz REM Radio Environment Map RF Radio Frequency RFID Radio Frequency IDentification R-GSM Railway Global System for Mobile communications Rx Receiver SLA Service Level Agreement Tx Transmitter UHF Ultra High Frequency UL UpLink |
517a52b828a3794ba841b8ecef541827 | 101 537 | 4 Participants | Frank Siebert Bundesnetzagentur Friedbert Berens FBConsulting Sarl, Luxembourg Georg Ramsch Checkpoint Dirk Schattschneider Deutsche Bahn AG Daniel Büth FEIG ELECTRONIC GmbH Markus Desch FEIG ELECTRONIC GmbH |
517a52b828a3794ba841b8ecef541827 | 101 537 | 5 Background Information | In summer 2009 a first feasibility test between R-GSM and RFID was carried out. The results of this test showed that it is feasible for RFID Systems to co-exist in the band 918 MHz to 921 MHz with ER-GSM (i.e. ER-GSM BS transmit band) without causing unacceptable levels of interference. ETSI ERM set up STF 397 to develop procedures, techniques and solutions to achieve co-existence of UHF RFID devices with the victim radio service ER-GSM. In order to achieve more information on the parameters necessary to optimise co-existence, STF 397 performed a second test where they made some more detailed measurements. The results of the measurements should be used to define suitable mitigation strategies to ensure acceptable protection of ER-GSM. Furthermore the measurements should verify the initial assumptions of STF 397 and should form a basis for the definition of suitable test parameters for a test procedure for an RFID interrogator. This document describes the test methods and results of the second co-existence test performed at Kolberg, which should help the STF to define DAA or similar techniques, test procedures and test parameters. |
517a52b828a3794ba841b8ecef541827 | 101 537 | 6 Equipment under Test | In order to perform the tests the following equipment was used: • R-GSM: - 1 × R-GSM base unit (R&S CMU 200 BS); - 1 × R-GSM terminal (Cab Radio, Funkwerke Hörmann with Sagem® radio module MRM R2); - 1 × R-GSM terminal (GPH, Sagem® ). ETSI ETSI TR 101 537 V1.1.1 (2011-02) 8 • RFID: - 2 × RFID interrogators from FEIG (ID-ISC.LRU3500), - 1 × CISC RFID Tag Emulator R1.1. The RFID interrogator was operated in accordance with the four channel plan described in EN 302 208 (V1.2.1) [i.1]. For the purpose of the tests the frequency range of the interrogator was shifted to the existing R-GSM frequencies 918 MHz to 924 MHz (3 MHz overlap with R-GSM). In some of the tests the channel width of the transmissions from the interrogator was increased to 400 kHz. |
517a52b828a3794ba841b8ecef541827 | 101 537 | 7 Tests with R-GSM as a victim | The purpose of these tests was to determine the conditions under which RFID can cause interference to the R-GSM receiver in a mobile unit. To verify the worst interference conditions for the R-GSM receiver in this part of the test session, the R-GSM receiver was tested with the interrogator operating in different modes. In this first set of measurements the behaviour of the R-GSM receiver was tested in its various operating modes and at different simulated distances from the Base station. This was done by increasing the attenuation that can be inserted until the Rx-Qual value reported by the mobile unit changed from 1 to 2. In the second part of the test session the behaviour of the R-GSM receiver was tested with different RFID bandwidths and modulation scenarios. It should be noted that some of the RFID modulation scenarios were not typical of those found in most RFID communication systems. These unusual modulation scenarios were tested in order to determine the worst case conditions for an R-GSM receiver. Conducted measurements were also performed to obtain protection distances for the various scenarios. |
517a52b828a3794ba841b8ecef541827 | 101 537 | 7.1 Measurement setup | The equipment was configured as shown in figure 1. This measurement setup was the same as that used in the first co-existence tests between ER-GSM and RFID. Figure 1: Setup for R-GSM as a victim ETSI ETSI TR 101 537 V1.1.1 (2011-02) 9 |
517a52b828a3794ba841b8ecef541827 | 101 537 | 7.2 General Measurement procedure | The CMU behaved like a R-GSM Base Station transmitting the BCCH, i.e. all time slots on air with a constant Tx-level. The Tx-level of the CMU was adjusted to give different input levels at the Cab Radio. The Tx-levels were specified in the test sections below. The Rx-level of the R-GSM signal and the levels generated by the RFID interrogators were measured with a spectrum analyser. The downlink bandpass filter protected the analysers from the high uplink level of the Cab Radio. During testing the interrogator was set to the nominal frequency of 921,4 MHz and shifted in 100 kHz steps towards 925 MHz. The output signal level from the interrogator was adjusted by its attenuator to give the specified conditions on the display of the cab receiver. The CMU was initially set to transmit at a frequency of 921,4 MHz. |
517a52b828a3794ba841b8ecef541827 | 101 537 | 7.3 Measurement results |
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