hash stringlengths 32 32 | doc_id stringlengths 7 13 | section stringlengths 3 121 | content stringlengths 0 2.2M |
|---|---|---|---|
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.4.2 UK Defence specifications | The UK Defence Standards give useful advice on limits for noise exposure for military personnel. It is acknowledged that the UK Health and Safety at Work Act also applies to service personnel and so the limits recommended are similar to civilian limits. Military standards provide some of the few sources of information ... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.5 Other relevant publications | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.5.1 Indecent exposure | In the United Kingdom, the Royal National Institute for Deaf People (RNID) and the Trades Union Congress (TUC) have jointly published a report on noise at work [5]. This report, entitled "Indecent exposure" claims that "call centre workers are being exposed to loud, sometimes painful, noise levels leaving them with dul... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.5.2 Hearing aid limits | Particularly in view of the use of amplified handsets to assist the hard of hearing, it is necessary to consider whether different limits should be applied for those users. Wide variations of susceptibility to hearing loss are recognized [6] but it is generally assumed that, due to the normal mechanism of hearing loss,... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7 Further considerations | Before beginning discussion on where to go next, there are a number of factors that have to be taken into account. |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.1 Origins of limits | Although the published information suggests that the presently used limits are based upon detailed considerations of noise exposure, a study of the unpublished contributions that led up to the recommendations reveal that in fact this is not so. They were originally derived from figures that were being achieved at the t... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.2 Free field/eardrum correction | One point of uncertainty noted by the FDA was the allowance for the difference between free field and artificial ear measurements. They noted that it was suggested that some ears amplified the free field levels by as much as 8 dB so that the artificial ear measurement was said to be artificially high and that 8 dB shou... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.3 Risk factors | When considering limits to be set, statistical risk of the occurrence of damage is a major factor. It may reasonably be considered that the permitted exposure of members of the public should be less than that of employees who receive some financial compensation for the risk to which they are exposed in the normal cours... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.4 Exposure lifetime | If a limit were to be set based upon noise at work considerations, some correction would need to be made for the exposure lifetime, as the period of telephone usage is likely to be greater than the 30 or 40 years exposure expected at work. Such a correction could be derived from BS 5330 [45] or ISO Publication 1999 [33... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.5 Exposure period | If a limit were to be set based upon noise at work considerations, some correction would need to be made for the daily exposure period, with different exposure periods being assigned to differing usages or exposures. The exposure of call centre operators would clearly be different from domestic users. The exposure to s... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.6 Frequency content | Based on over 200 octave spectra of various noisy environments in industry, Hardy [52] stated that on average, the spectra of industrial noises are almost flat with frequency. However the deviations from that average are great. This is the type of exposure for which the noise at work regulations were designed. Some arg... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.7 Volume controls | If a limit were to be set based upon noise at work considerations, the likely use of any fitted volume control would need to be considered. The information given in subclause 4.5 would suggest that there is little margin left for the use of a volume control to increase the level of the received signal. An RLR of -19 dB... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.8 Impulsive shocks | Except for the work of Price [49] and [50] on the critical level, the few documents that deal with impulsive sounds [53], [54], [55] and [56], refer mostly to gunfire at rates of 100 rounds/day. There is little to be found on limits for occasional shocks as would occur in telephone usage. In a document on levels of env... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 7.9 Tone callers | Although the present continuous test limits arose from exposure to tone callers, especially when the earphone was used as the tone caller, few standards give applicable tests. This is especially important when the tone caller is on the handset of a portable telephone. All of the current tests specified are with the ear... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 8 Conclusion | The present document provides a collection of extracts from current standards, approval documents and other relevant background information on the subject of acoustic shock and the protection of the user from injury arising from the acoustic output of telecommunications terminal equipment. It is intended as an input to... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 1 Scope | The present document provides background information on the performances of the GSM Adaptive Multi-Rate (AMR) speech codec. Experimental test results from the Verification and Characterisation phases of testing are reported to illustrate the behaviour of the GSM AMR in multiple operational conditions. |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 2 References | The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. • For a specific reference, subsequent revisions do not apply. • Fo... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 3 Definitions and abbreviations | |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: Adaptive Multi-Rate (AMR) codec: Speech and channel codec capable of operating at gross bit-rates of 11.4 kbit/s (“half-rate”) and 22.8 kbit/s (“full-rate”). In addition, the codec may operate at various combinations of speech and chan... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 3.2 Abbreviations | For the purposes of the present document, the following abbreviations apply: A/D Analogue to Digital ACR Absolute Category Rating ADPCM Adaptive Differential Pulse Code Modulation AMR Adaptive Multi-Rate BSC Base Station Controller BTS Base Transceiver Station C/I Carrier-to-Interfere ratio CI Confidence Interval CNI C... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 4 General | |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 4.1 Project History | Following the standardisation of the EFR speech codec, the SMG2 Speech Expert Group (SEG) and especially the SQSG (Speech Quality Strategy Group) were tasked by SMG to study possible strategies for the continuous improvement of the end to end performances of the speech service in GSM networks. SEG was specifically aske... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 4.2 Overview of the AMR Concept | Unlike previous GSM speech codecs (FR, EFR, and HR) which operate at a fixed rate and constant error protection level, the AMR speech codec adapts its error protection level to the local radio channel and traffic conditions. AMR selects the optimum channel (half or full rate) and codec mode (speech and channel bit rate... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 4.3 Functional Description | The AMR speech codec includes a set of fixed rate speech codecs modes for half rate and full rate operation, with the possibility to switch between the different modes as a function of the propagation error conditions. Each codec mode provides a different level of error protection through a dedicated distribution of th... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 4.4 Presentation of the following sections | The following sections provide a summary of the Characterisation Phase test results and background information on the codec performances analysed during the Verification Phase. Sections 5 to 9 summarise the codec subjective quality performances under different representative environmental conditions as measured during ... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 5 Quality in Clean Speech and Error Conditions | The codec performances in clean speech and error conditions were measured in Experiment 1a (Full Rate) and 1b (Half Rate) of the Characterisation phase of testing. The clean speech performance requirements were set for the best codec mode in each error condition as defined in the following table: Table 5.1: Best Codec ... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 8 Performances with the Codec Adaptation turned on | Experiments 4a (Full Rate) and 4b (Half Rate) of the Characterisation phase of testing were designed to evaluate the AMR performances with the adaptation turned on in long dynamic C/I profiles representative of operational propagation conditions. Multiple C/I profile were generated simulating different behaviour of the... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 9 VAD/DTX Performances | The objective of Experiment 7 of the characterisation test plan was to evaluate the degradation induced by the activation of the voice activity detection and discontinuous transmission on the link under test7. The experiment was divided in 4 sub-experiments to separately test the effect on the Full Rate and Half Rate c... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 10 Performances with DTMF tones | Twelve experiments were performed during the verification phase to evaluate the transparency of the AMR codec modes to DTMF tones. The corresponding test conditions are listed in Table 10.1. The experiments were limited to error free conditions only. The frequency deviation was set for the duration of a digit, and was ... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 11 Transparency to Signalling tones | The transparency to network signalling tones was tested for all 8 codec modes using typical French and German signalling tones. French Signalling Tones Five different types of French network signalling tones were tested: Two different dial tones, one ringing tone, a busy tone and a special information tone. The descrip... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 12 Performances with special input signals | The behaviour of the AMR speech codec in presence of multiple “special input signals” was tested during the Verification Phase. These tests included: Overload conditions Additional background Noises and Talkers Music signals Idle channel behaviour ETSI ETSI TR 101 714 V7.2.0 (2000-04) 25 (GSM 06.75 version 7.2.0 Releas... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 13 Language Dependency | The selection and characterisation tests were performed by a large number of laboratories world-wide using different languages (see Annex A). Tests were performed in: English (US & UK), French, German, Italian, Mandarin, Spanish The results reported by the different laboratories were consistent. No significant quality ... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 14 Transmission Delay | The transmission delay of a communication using AMR has been evaluated using the same method as for the previous GSM speech codecs [2, 3 & 4]. The reference system delay distribution for the downlink and uplink directions are provided in figures 14.1 and 14.2 respectively. The speech transcoders are assumed to be remot... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 15 Frequency Response | NOTE: The frequency response is essentially given as a piece of additional information. It should not be used to qualify the codec performances in terms of perceived quality or DTMF transparency. The frequency response of the AMR codec was evaluated by computing the logarithmic gain of the frequency response of each co... |
398be09aa2fd412ecd019100ca4c579c | 101 714 | 16 Complexity | Editor’s Note 2: Section based on the content of Tdoc SMG11 158/99. This document was produced before a final agreement was reached on the format of the Abis and Ater TRAU frames. The final format could have an impact on the delay figures presented below. The AMR speech codec modes complexity were evaluated using the m... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 1 Scope | The present document should be read in conjunction with the normative document [i.2] in order to assist network operators, systems integrators, and equipment manufacturers in the realization of satellite based interactive services. The present document should be interpreted as recommendations or good practices but not ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 2 References | References are either specific (identified by date of publication and/or edition number or version number) or non-specific. • For a specific reference, subsequent revisions do not apply. • Non-specific reference may be made only to a complete document or a part thereof and only in the following cases: - if it is accept... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 2.1 Normative references | The following referenced documents are indispensable for the application of the present document. For dated references, only the edition cited applies. For non-specific references, the latest edition of the referenced document (including any amendments) applies. Not applicable. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 2.2 Informative references | The following referenced documents are not essential to the use of the present document but they assist the user with regard to a particular subject area. For non-specific references, the latest version of the referenced document (including any amendments) applies. [i.1] ETSI EN 300 421: "Digital Video Broadcasting (DV... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 3 Definitions, symbols and abbreviations | |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 3.1 Definitions | For the purposes of the present document, the terms and definitions given in [i.2] and the following apply: Assured Forwarding (AF): PHB group standardised by IETF Behavior Aggregate (BA): DS behavior aggregate Best Effort (BE): PHB standardised by IETF; typically the default PHB in a system Differentiated Services (DS... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 3.2 Symbols | For the purposes of the present document, the following symbols apply: Eb/N0 The ratio between total power used for transmission divided by the number of information bits per second and the noise power density. Annex D gives an example of the measurement and calculation of Eb/N0 Es/N0 The ratio between the energy per t... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 3.3 Abbreviations | For the purposes of the present document, the abbreviations given in EN 301 790 [i.2] and the following apply: ABR Available Bit Rate ACK ACKnowledgement ACM Adaptive Coding and Modulation AES Aircraft Earth Station AGC Automatic Gain Control AF Assured Forwarding AMSS Aeronautical Mobile Satellite Service AMT Aggregat... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 4 Reference models | The Reference Model for an interactive satellite network depicted in [i.2] includes all interconnections among Network Control Centre, Traffic Gateway(s), Feeder(s) and Terminals, which are possible from a functional viewpoint. In practice not all these interconnections will be implemented. Also, some functional blocks... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 4.1 Architecture with co-located NCC, Gateway and Feeder | The simplest architecture is an interactive satellite network with a single Traffic Gateway and a single Feeder co-located in an Earth Station (see figure 4.1). The Network Control Centre is possibly also collocated. NCC Gateway Feeder Terminal controls User data return Interactive Network Adapter Broadcast Network Ada... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 4.2 Architecture with multiple feeders | When more Feeders exist in the interactive satellite network, the terminals should be able to switch from one to another, without losing network synchronization (see figure 4.2). In order to achieve this, the following network architecture is envisaged. Terminals are equipped with at least two receivers. One receiver i... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 4.3 Architecture with transparent mesh connectivity | By incorporating one or more TDMA burst receivers the RCST will be capable of receiving TDMA bursts as well as transmitting them. This allows RCSTs to communicate directly over a bent-pipe satellite, as indicated in figure 4.3, as well as simultaneously operating according to the architectures of figures 4.1 and 4.2. F... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 4.4 Architecture with regenerative satellites | The normative document [i.2] extends the standard to Regenerative Satellite Multimedia Systems (RSMS), i.e. systems in which the communications between NCC, Gateways, Feeders and terminals transit through a satellite with On-Board-Processing (OBP) functions (as opposed to a conventional, bent-pipe, satellite). This all... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 4.4.1 On board switching requirements | RSMS require onboard routing or switching of signals between input and output ports. Different on board switching architectures can be used; circuit-switched, frame-switched, packet or cell switched architecture. In case of RSMS performing packet or cell switching, there are two types of information identified as neces... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 4.4.2 RSMS Network Architecture | A RSMS network can be configured to support both star and mesh topologies based on DVB-RCS specification for the return channel and DVB-S/S2 specification for the forward channel. As for a transparent satellite network, the regenerative satellite network in star topology supports access traffic to/from a gateway. In a ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 5 Forward link | Figure 5.1 shows one way to implement the forward link signalling from the NCC (the SI-information for RCS) to an existing DVB-S or DVB-S2 system. The SI-tables with signalling data to the RCST from the NCC are represented as binary data (for example in binary files). These binary data are sent to the Gateway and put i... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 5.1 Assignment and selection of FL elementary streams | An NCC may assume that the RCST automatically receives MPE elementary streams (of the stream type 0x0D and applying table_id 0x3E) that are listed in the feeder FL service specification given in the PMT. It is recommended that the RCST automatically starts receiving MPE traffic from these elementary streams as part of ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 5.2 Specific use of FL tables and formats | |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 5.2.1 FL service specification in PMT | It is recommended that the NCC uses stream type 0x05 (stream with private sections according to [i.50]) for declaration of an elementary stream that carries any of the RCS C&M tables, TIM as well. Elementary streams of user defined stream types may not be recognized by an RCST, even if the RCS content descriptor is app... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 5.2.1 Optional use of SDT | An SDT can contain one or more data_broadcast_descriptors that indicates characteristics of MPE as applied by the feeder. SDT is considered optional by [i.2]. An RCST should thus not rely on receiving the data_broadcast_descriptor. It should not be expected that RCST implementations follow specific configurations given... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 5.2.2 Assumptions concerning IP encapsulation | It is recommended that a feeder system applies native IP encapsulation in MPE. Alternative formats for IP encapsulation, e.g. like ATM based data piping as specified by [i.2] and LLC/SNAP based encapsulation in MPE as specified by [i.34] should only be applied by the feeder if specifically known to be supported by the ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 5.3 Applicability of SI Tables in RSMS systems | This clause provides information on the applicability of SI tables when used in RSMS. Different RSMS OBP implementations result from the apportionment of the functions between three entities: the RCS terminals, the NCC and the onboard processor. Table 5.3 provides examples of signalling flows and tables processing. Tab... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6 Return link | Symbol rate is not defined in the normative document [i.2]. In some of the following clauses, specific symbol rates are mentioned by way of example. It should be noted that the choice of symbol rate can have an impact on other system parameters, for example: phase noise performance for the lower end and link budget for... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.1 RCST synchronization | For administrative and technical reasons the location of an RCST is known to the network operator. An RCS system can be designed assuming an accuracy of the location (longitude, latitude and altitude) of the RCST of no more than a few kilometres. Some network operators may require a better accuracy. It is recommended t... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.1.1 RCST internal delay compensation | The definition of the terminal burst transmission time reference for an RCST using DVB-S is found in [i.2]. The same type of NCR reconstruction and burst synchronization is assumed by an RCST using DVB-S2 by applying an ideal delay-less DVB-S2 receiver. The ideal delay-less DVB-S receiver is, in addition to compensate ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.1.2 NCR interpretation for DVB-S2 | Adopting DVB-S2 in DVB-RCS systems with minimal changes required to keep the format of the signalling info. This implies that the Network Clock Reference is still delivered as a series of time stamped MPEG TS packets (NCR packets). The purpose of Network Clock Reference (NCR) delivery is however to provide a common clo... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.1.3 DVB-S2 TX implementation aspects | Figure 6.1: Functional block diagram of the DVB-S2 system ... PLHEADER n PLHEADER n+3 XFECFRAME n+2 XFECFRAME n+3 XFECFRAME n Latch SOF Trigger 7 5 6 12 11 10 8 4 2 1 9 3 NCR Clock NCR field (42-bit) NCR packet NCR field first bit SOF n PLHEADER n+2 ... ... Figure 6.2: Association of NCR to SOF event in the transmitter... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.1.4 DVB-S2 RX implementation aspects | The main requirement is to associate without ambiguity detected SOF with decoded frames (and hence with NCR fields within the frame), and to make this information available to the NCR synchronization circuit in the terminal. Decoding processing delays are far less critical. An association and interfacing approach that ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.1.5 VCM/ACM aspects and Multiple TS aspects | Typically the highest protection level in use in the system is applied to the forward link signalling. Typically the mode adaptation block is configured to send signalling info with sufficiently high priority and therefore, to maintain more or less constant NCR intervals. In general (also with single TS!) NCR fields ca... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.1.6 Combining TS and GS | When GS and TS are combined, the non-IP based RCS signaling will be transported in the TS. Generic Stream Encapsulation (GSE) as specified in [i.57] is recommended as the encapsulation for IP in the GS. ETSI ETSI TR 101 790 V1.4.1 (2009-07) 33 |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.2 Burst format | |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.2.1 Contention access | Multiple access on traffic slots is based on a reservation mechanism, in which traffic slots are uniquely assigned to the requested RCST through the use of the RCST's Group_ID and Logon_ID. The Network determines the originator of the bursts transmitted in these allocated slots through the knowledge of the TBTP. Howeve... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.2.2 Acquisition Bursts | The fixed symbol pattern transmitted in ACQ bursts is referred to as a "frequency sequence", because of its common use for determining and correcting the transmit frequency. An example for the "frequency sequence" in the transmission of an ACQ slot could have the format as: B79A A5B7 625D F39F 8A07 09E8 AE86 F1FA E063 ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.2.3 Determination of the implicit number of MPEG2 packets in a burst | When using the optional MPEG2 traffic bursts, the number of packets is implicitly given in the TCT. The RCSTs can apply the following procedure to find this number. 1) Step1: Convert timeslot_duration (tsd) and burst_start_offset (bso) from upcrmsf into uimsbf: • An n-bit τ of PCR counts in upcrmsf is converted to uims... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.2.4 Application of MPE in the return link | The MPE MAC address content for the return link is undefined by [i.2], and implementations cannot be expected to put specific information into the MAC address field. The content of the MPE MAC address field is generally recommended discarded at the GW. The use of 8 bit alignment of encapsulated IP information is recomm... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.3 Randomization for energy dispersal | A complementary non self-synchronizing de-randomizer is used in the receiver to recover the data randomized as described in EN 301 790 [i.2]. The de-randomizer is enabled after detection of the preamble. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4 Coding | When the ATM profile is used, the payload of each burst always constitutes a single code word, independently of the payload size and the type of coding (concatenated RS/convolutional or Turbo). In contrast, when the optional MPEG profile is used, each MPEG-TS packet is encoded as a separate codeword. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.1 CRC error detection code | As stated in EN 301 790 [i.2], the CRC code is mandatory on turbo coded CSC bursts. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.1.1 CRC coding example | CRC coding of a CSC burst is taken as an example. The clear, randomized and CRC coded sequences are listed in table 6.2 from left to right in order of transmission, in hexadecimal format, with msb sent first. CRC coding is applied after randomization. Since EN 301 790 [i.2] defines CRC computation as a polynomial divis... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.2 Reed Solomon outer coding | The error-correction capability of the RS code is always 8 bytes, independent of the information block size. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.3 Convolutional inner coding | The convolutional encoder should be flushed after each MPEG packet. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.4 Turbo code | The use of the optional scheme of introducing new permutation schemes is generally adviced against as such schemes will typically have to be accompanied by corresponding custom FEC block sizes and the use thus creates a risk for lack of interoperability. New permutation schemes can be exploited in a system dependent cu... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.4.1 General principles of coding and decoding | Figure 6.3 depicts the general principle of the Turbo encoder specified in clause 6.4.4 of EN 301 790 [i.2]. It is a parallel concatenation of two double-binary, circular, recursive and systematic convolutional encoders (C1 and C2 in figure 6.3). A B s1 Encoder C1 Encoder C2 Interleaver puncturing Codeword systematic p... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.4.2 Puncturing examples for DVB-RCS Turbo Code | Figures 6.4a and 6.4b illustrate the puncturing process for the Turbo code. A Y1 B W1 A Y1 B A Y1 B A Y1 B A B A Y1 B A Y1 B A Y1 B Y1 i A B A Y1 B A Y1 B A Y1 B Y1 N-1 N-2 N-3 N-4 0 4 3 2 1 6 5 7 A Y2 B W2 A B A B A B A B A B A B A B j A B A B A B A B N-1 N-2 N-3 N-4 0 4 3 2 1 6 5 7 W2 W2 W2 W2 W2 W2 W2 R=1/3 R=2/5 (0... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.4.3 Implementation trade-offs | For the SISO computation, a Maximum-A-Posteriori (MAP) principle as popularized by the Bahl-Cocke-Jelinek-Raviv algorithm ( [i.2] and [i.3]) gives the best performance but its complexity is rather prohibitive, with today's technology. A good trade-off is to use the Sub-MAP algorithm, also called Max-Log-MAP or Dual Vit... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.4.4 Implementation feasibility | With the above implementation trade-offs, Turbo decoding of the DVB-RCS code requires modest silicon resources. At the "2nd Symposium on Turbo codes and related topics" [i.4], 2 implementations, one on FPGA/CPLD and one on an ASIC qualified for space-borne applications, were reported. Implementation aspects are shown i... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.5 Preferred coding combinations | The turbo coding scheme is recommended due to its superior performance relative to the concatenated coding scheme. It can be expected that there are fewer interoperability issues when applying turbo coding as this is the preferred scheme in most implementations. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.5.1 Concatenated coding scheme | The preferred coding combinations for concatenated-coded systems are summarized in table 6.4. Table 6.4: Preferred coding combination for concatenated-coded systems Burst Type Randomization CRC Reed-Solomon Convolutional TRF Yes No Yes Yes SYNC Yes See below Yes Yes CSC Yes Yes No Yes ACQ N/A N/A N/A N/A The rationale ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.4.5.2 Turbo coded systems | The preferred coding combinations for Turbo coded systems are summarized in table 6.5. Table 6.5: Preferred coding combination for Turbo coded systems Burst Type Randomization CRC Turbo Code TRF Yes No Yes SYNC Yes See below Yes CSC Yes Yes Yes ACQ N/A N/A N/A The rationale for these choices includes the following: • R... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.5 Modulation | The guard time is a "silent" time interval that separates one burst from the following one. Typical guard time intervals associated with each type of burst are given in table 6.6. The guard interval consists of three parts: a guard interval for transients, based on the symbol rate of the transmission (allowing the "rin... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.5.1 BURST-TO-BURST interference control | The burst should not introduce degradations to adjacent bursts. Figure 6.7 shows a typical power envelope of a burst. It should be noted that the instantaneous power can fall below the "inner" envelope, due to zero-crossings in the transmitted signal. (-6 dB) T T T (N-1)T (-20 dB) T T (-30 dB) T (-30 dB) (-6 dB) (-20 d... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.5.2 Control of EIRP, OBO and interference to adjacent channels | The manufacturer of the RCST needs to state precisely the operating range of the EIRP control of the RCST. This is because different system operators may use different strategies for RCST EIRP control. In some system designs, a wide rain fade margin may be expected and tight RCST uplink power control exercised. In othe... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.6 MAC messages | |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.6.1 Methods based on the Satellite Access Control (SAC) field | |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.6.1.1 SAC field composition | Examples of use of Channel id In this clause channels are defined as independent communications paths, to which different capacity may be dynamically allocated (just like capacity allocation to distinct terminals) and separately managed, according to different traffic and network profiles. The rationales for allowing t... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.6.2 Data Unit Labelling Method (DULM) | It is adviced against reliance on DULM in systems that are not designed to apply DULM according to a supplemental specification, due to the risk of lack of support in implementations and the risk of incompatibility. As stated in [i.2], the DULM with ATM transport does not use the method described in [i.5], but uses AAL... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.7 Multiple access | There may be advantages in organizing the superframe according to the following conditions (see also clause 8.2): • Frames should have the same duration. • A frame on a given frequency should carry homogeneous traffic; that is, the bit rate, the code rate and the burst length should be constant. ETSI ETSI TR 101 790 V1... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.7.1 Example for segmentation of return link capacity | An RCST using the fixed MF-TDMA mode should not transmit while reconfiguring its transmission parameters. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.7.1.1 ATM traffic time slots | In order to illustrate the use of the normative document [i.2], an example for segmentation of return link capacity is given here. The segmentation follows the definition of Fixed MF-TDMA that can be found in clause 6.7.1.1 of the normative document [i.2]. Four peak information bit rates are considered: • 144 kbit/s. •... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.7.1.2 Optional MPEG traffic time slots | There are broadly two families of segmentation of return link capacity, one based on ATM traffic time slots and the other based on optional MPEG TS time slots. The selection of one or the other depends on many considerations pertaining to the network operator's strategy. Reasons for using MPEG time slots can be: • Bett... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.8 Capacity categories | Capacity requests will be issued from the RCST to the NCC to receive BoD. For RCS systems that implement service aggregate differentiation it is possible to differentiate the capacity requests by Request Class (RC) to support the NCC BoD controller in applying network-wide service differentiation. This clause provides ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.8.1 Request Classes and DS Behaviour Aggregates | An RC can be considered the representation to the satellite network of the traffic aggregated from a set of BA's, the traffic elements in the DS architecture. The RC aggregate is associated with a specific behaviour. An RC aggregate is considered the subject of a PHB group as the BA is considered the subject of a PHB. ... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.8.2 Request Classes and Capacity Categories | Each RC is identified by a unique Channel_ID in the communication between the RCST and the NCC. Each capacity request is issued with a reference to the RC corresponding to the associated traffic aggregate. Considering a DS-compliant RCST, Channel_ID = 0 should be associated with the default PHB, and the default PHB sho... |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.8.3 Request Classes and Admission Control | It may be desirable to support admission control per RCST and service to improve the user experience, and utilize resources more efficiently. RC's may be utilised to implement such admission control. This may be supported by supplemental specifications to coordinate the NCC and RCST implementations. |
d1b2bee55ecd2d18f12cc06899493bcb | 101 790 | 6.8.4 Guidelines for the Capacity Categories | Similar guidelines as found in this clause as well as supplemental guidelines can be found in the SatLabs system recommendations in [i.58]. |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.