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68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.1 Components of a cable network | The network consists of an ensemble of active components, splitters, multitaps and fibre and coaxial cables connecting the DVB-C2 transmitter in the head end and the DVB-C2 receiver in the customer home. The network can be split into the operator's network part and the customer in-home network part with the network ter... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.1.1 The operator part of the network | The operator part of the network should be constructed and maintained so that all signals at all homes have an appropriate signal level. The required signal characteristics for FM radio, analogue TV and DVB-C signals, including the minimum and maximum values, are specified in IEC 60728-1 [i.18]. Requirements for DVB-C2... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.1.2 The customer part of the network | The in-home coaxial network of a customer may range from a single coaxial lead directly connecting a customer receiver like an analogue TV set, STB, IDTV or home gateway up to an extended coaxial network with branching point and coaxial cables to different rooms with or without a home amplifier. Installations and compo... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2 Distortion signals | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.1 Echo | Echo is caused by reflection of the signals at impedance transitions occurring at connectors, components, damaged cables, incorrectly (or not) terminated cables. For the development of the DVB-C2 standard [i.1], the worst-case echo as specified by the IEEE 802.14 [i.16] model has been assumed as a reference. This IEEE ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.1.1 Echoes caused by the operator network | In the networks of Ziggo (NL, cascades of 2 amplifiers) and Telenet (B, cascades of 11 amplifiers) the echo was measured at 4 multitaps using a DVB-C analyser [i.17]. The signal delay and magnitude is indicated in the open symbols of table 17. To compare the echo with the IEEE 802.14 mask [i.17], the signal power of al... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.1.2 Echoes caused by the in-house network of the customer | Inferior in-home coaxial networks may severely degrade the echo, in particular when resistive splitters are used and coaxial cable is not properly terminated. However, echo measurements showed that even in such inferior in-home networks the echo still does not exceed the IEEE 802.14 [i.17] mask. ETSI ETSI TS 102 991 V1... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.2 Ingress | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.2.1 Terrestrial broadcast services | Ingress of DVB-T signals is known to occur in the vicinity of the DVB-T transmitters. The use of high quality leads and passive components is an effective remedy. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.2.2 Human activity in the home environment | In home activity such as switching on and off and plugging in- and out of electric equipment may cause severe burst events. The impact of such burst events on the DVB-C2 performance is not yet known. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.2.3 Mobile services (Digital Dividend) | The EC intends to allocate the 790 MHz to 862 MHz frequency band for future mobile communication services (e.g. using the fourth generation mobile technology: LTE). If this allocation is adopted, mobile transmission in the in-home environment will severely distort the DVB-C2 signals. The impact of this use currently is... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.3 Nonlinear behaviour of components | In cable networks the amplifiers operate at a high output level. Because of this high output signal level, the non-linear behaviour of the amplifiers becomes apparent. Commonly in the field of HFC engineering, the component is assumed to behave according to the non-linear response function: In the current practice only... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.3.1 Narrowband cluster beats | From the viewpoint of intermodulation, the analogue signal is dominated by the narrow band carrier; the broadband video signal and the FM audio signals have a lower spectral density and can be neglected. Because of the convolution, intermodulation of an analogue signal with another analogue signal produces a narrowband... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.3.2 Broadband random noise | In contrast to the intermodulation of a (narrowband) analogue carrier with an analogue carrier, intermodulation of an analogue signal with a (broadband) digital carrier, either DVB-C or DVB-C2, and intermodulation of a digital carrier with a digital carrier yields a broadband, random noise like distortion signal. The r... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.2.3.3 Impulse noise | At high composite loads, impulse events start occurring [i.20]. The generation of impulse events is demonstrated in figure 43. Figure 43 shows the probability density function (PDF) of a baseband real time distortion signal sample as recorded with a fast capturing system. The RF distortion signal is from a single ampli... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.3 Signal Requirements | The networks will carry a mixed network load of FM radio, analogue TV (PAL or SECAM), DVB-C and DVB-C2 signals. For all services the appropriate signal levels and the signal quality levels must be warranted. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.3.1 Signal levels | The minimum signal levels at the system outlet for FM radio, analogue TV and DVB-C are specified in IEC 60728-1 [i.18], clause 5.4. Currently, IEC 60728-1 [i.18] provides no requirements for the DVB-C2 signal level at the cable system outlet. A guideline for the DVB-C2 signal level can be derived from the sensitivity f... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.3.2 Signal quality requirements | The required quality of the signals at the system outlet for FM radio, analogue TV and DVB-C are specified in IEC 60728-1 [i.18]. For all services, the signal quality must be compliant to the appropriate specifications. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.3.2.1 Analogue TV | The carrier-to-noise ratio (C/N) requirements for analogue TV is specified in IEC 60728-1 [i.18], paragraph 5.8. The carrier-to-intermodulation ratio (C/I) is defined as the ratio between the carrier signal and the weighted sum of the CSO and CTB cluster beats measured as specified in IEC 60728-1 [i.18], paragraph 4.5.... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.3.2.2 FM radio | The carrier-to-noise ratio (C/N) is specified in IEC 60728-1 [i.18], paragraph 5.8. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.3.2.3 DVB-C | The minimum composite intermodulation noise ration (CINR) is specified in IEC 60728-1 [i.18], paragraph 5.8. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.3.2.4 DVB-C2 | For DVB-C2 currently IEC 60728-1 [i.18] does not provide the signal quality requirements. However, DVB-C2 has been designed and optimized for the existing HFC networks. The simulation scenarios used for the system validations have been defined with the minimum network requirements as specified in IEC 60728-1 [i.18] in ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.4 Network optimization | Operators will have to establish the optimum DVB-C2 carrier level for their networks, which allows robust and error free DVB-C2 transmission at a sufficiently high modulation profile whereas at the same time the other services (FM radio, analogue TV and DVB-C) are sufficiently protected. Here we will summarize and expl... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.4.1 The effect of the DVB-C2 carrier level | Figure 47 gives an illustration of the impact of the new DVB-C2 services on the nature and level of the distortion signals. When deploying DVB-C2, an operator will not raise or lower the signal level of the existing FM radio, analogue TV services and the DVB-C. Instead these signal levels will be conserved. For DVB-C2 ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.4.2 Impact of the DVB-C2 signal level on DVB-C2 performance | Figure 48 schematically shows the impact of the DVB-C carrier level on the signal quality and performance of DVB-C services for a single component or a cascade with a mixed analogue and digital load. For a load with DVB-C2 carriers there is no information available yet; however, a qualitatively similar behaviour can be... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.4.3 Impact of the DVB-C2 signal level on analogue TV services | Raising the DVB-C2 signal level above a specific value will increase the random noise distortion level and eventually result in the generation of impulse events. It does not affect the number and magnitude of the cluster beats. Therefore, higher DVB-C2 signal level will reduce the C/N of the analogue TV signals whereas... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 9.4.4 Non linear behaviour of active components in case of digital loads | This clause contains preliminary findings based on first simulations and measurement of higher order intermodulation interference effects in cable networks caused by digital signals. It will be subject to future revisions of the DVB-C2 implementation guidelines to further elaborate on the impact of non linear distortio... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10 Receivers | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1 Synchronisation Procedure | The DVB-C2 signalling scheme, consisting of Layer 1 and Layer 2 signalling, allows the receiver to acquire all relevant information required to tune to the targeted service. This clause describes procedures of the receiver to detect and process the relevant information. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.1 Initial Acquisition | The initial acquisition is performed after the first switch-on of the receiver to detect the available DVB-C2 signals. The procedure works as depicted in figure 52. Details on the different blocks are given in the following clauses. Figure 52: Initial acquisition flow chart Firstly, the DVB-C2 receiver selects one of t... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.1.1 Spectrum Detection | The spectrum detection is required to tune correctly to a DVB-C2 signal. In order to be able to decode the complete L1 part 2 signalling, the receiver must be able to receive at least 7,61 MHz (or 5,71 MHz in the 6 MHz mode) of one DVB-C2 signal. It is especially required that the receiver does not try to decode the L1... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.1.2 Guard Interval Correlation | Most signals within the cable environment are not OFDM signals. Therefore, the detection whether the signal is an OFDM signal is extremely useful. As the Guard Interval is a cyclic copy of the useful part of the OFDM symbol, the receiver can try to correlate the Guard Interval against the useful part. If a peak (or sev... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.1.3 Coarse Time and Fractional Frequency Synchronisation | The coarse time and the fractional frequency synchronisation can also be achieved by means of the Guard Interval. For details see [i.12]. ETSI ETSI TS 102 991 V1.2.1 (2011-06) 101 |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.1.4 Preamble Detection and Synchronisation | Within this clause we assume that the temporal synchronization to the OFDM symbols as well as the fractional frequency offset compensation has already been achieved. Thus, we are able to demodulate the data modulated on each OFDM sub-carrier correctly, but we cannot perform channel estimation and we do not know the act... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.1.5 Preamble Data Decoding Procedure | The information transmitted within the preamble is cyclically repeated within the L1 Signalling Blocks every 3 408 OFDM sub-carriers, or 7,61 MHz in 8 MHz operation. However, it is not ensured that the tuning window of the receiver front-end is aligned to an L1 Signalling Block. Additionally, the number of preamble sym... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.1.5.1 Data Sorting | The tuning bandwidth of the receiver front-end is always wider than one L1 Signalling Block. Therefore, the receiver is able to receive the information within two blocks, and obtain the complete information by sorting of the data. Figure 57 shows an example. The receiver is optimally tuned to receive Data Slice 2. Howe... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.1.5.2 Preamble Header Decoding | See Data Slice Packet Header decoding. If the L1 block comprises several copies of L1 part 2 cells to fill the entire band of the L1 block, accumulation of those L1 part 2 cells improves the resultant SNR therefore decoding performance. In addition, if the preamble is composed of more than one OFDM symbol, the copy fro... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.2 Channel Tuning Procedure | For the tuning to a specific service, the receiver has already the information of the C2_delivery_system_descriptor. This descriptor includes the OFDM parameters, the tuning frequency to obtain the Layer 1 - part 2 signalling information and the DVB-C2 System Id. Start Tune to C2_system_tuning _frequency Preamble Found... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.3 Preamble Time De-interleaver | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.3.1 Phase of time de-interleaving | As the L1 TI block is synchronized to preamble boundary in time direction, the receiver can begin preamble time de-interleaving after C2 Frame detection. The receiver first detects the preamble and decodes L1 header to get information about preamble time interleaving parameters. Then, the receiver can immediately start... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.3.2 Pre-processing to time de-interleaving | The pre-processing from preamble synchronization to preamble time de-interleaving process is depicted in figure 59, which is a de-interleaving process as a counterpart to the time interleaving shown in figure 28 of [i.1]. L1 Header Removal Combining Preamble Sync Time De-interleaving XFECFRAME 1 XFECFRAME 2 H H H H 7.6... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.3.3 Memory-efficient implementation of time de-interleaver | Memory efficient way of de-interleaving for the preamble is very similar to that of de-interleaving for the Data Slice (see clause 10.2). The address generation and memory handling are exactly same. The only difference is that for the preamble de-interleaving, neither preamble pilot nor reserved dummy carrier for PAPR ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.1.3.4 Disabled time interleaving | The L1 time de-interleaving may be disabled in cases where the L1 time interleaving is not applied to the preamble in the transmitter side for the fast access to the L1 part 2 data or short latency application. In this case, it may still be useful to use the de-interleaver memory as a buffer, but the read and write seq... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.2 Time de-interleaving of payload data | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.2.1 Phase of time de-interleaving | As the TI block is synchronized to Data Slice boundary in the time direction, the receiver can begin time de-interleaving after C2 Frame detection. The receiver first detects the preamble and decodes L1 part 2 data to get information about time interleaving depth. Then, the receiver can immediately start de-interleavin... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.2.2 Memory-efficient implementation of time de-interleaver | The permutation function for the time interleaver is the same for each TI block within the C2 Frame and so it might appear that two blocks of memory are required in the de-interleaver. However, a more efficient method exists using only one TI block's worth of memory. The memory-efficient de-interleaver is shown in the ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.2.3 Disabled time interleaving | The time de-interleaving may be disabled in cases where the interleaving is disabled in the receiver side for short latency application. In this case, it may still be useful to use the de-interleaver memory as a buffer, but the read and write sequences will both be identical. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.3 Frequency de-interleaving of payload data | The frequency de-interleaver in DVB-C2 is applied to the equalised payload cells of a given Data Slice from one OFDM symbol to the next. The number of payload cells per Data Slice per OFDM symbol (NDS) can vary from symbol to symbol. NDS comprises the number of cells (KDS,max - KDS,min ) minus the number of continual p... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.4 Use of Pilots | Pilots can be used for typically the following four purposes: • C2-frame synchronisation. • Integer frequency offset estimation. • Channel estimation. • Common phase error estimation. The C2-frame synchronisation is introduced in clause 10.1, the frequency offset and channel estimation details are discussed in clause 1... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5 Phase noise requirements | Phase noise is specified as single sideband phase noise power in a 1 Hz bandwidth at a frequency f from the carrier frequency. The unit of L(f) is dBc/Hz, representing the noise power relative to the carrier power contained in a 1 Hz bandwidth centered at a certain offsets from the carrier (e.g. at 10 kHz offset). ETSI... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.1 Common phase error correction | Low-frequency phase noise causes common phase error. Since the random rotation of common phase error are (by definition) the same for every carrier within the same OFDM symbol they can be measured (and thus corrected if desired) by using the Continual Pilots (CPs). CPs are specified carriers which transmit reference in... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2 Channel Equalization | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2.1 Overview | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2.1.1 The need for channel estimation | The received carrier amplitudes output by the receiver FFT are not in general the same as transmitted - they are affected by the channel through which the signal has passed on its way from the transmitter. Consider the channel extent, which could be variously described as: the duration of the impulse response from the ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2.1.2 Obtaining the estimates | The channel estimate can be derived from the known information inserted in certain OFDM cells - a term we use for the entity conveyed by a particular combination of carrier (location in frequency) and symbol (location in time). These cells containing known information are known as pilot cells; they are affected by the ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2.2 Fundamental limits | The channel response Hk,l in general varies with both time (symbol index l) and frequency (carrier index k). The temporal variation corresponds to external causes such as Doppler shift and spread, but also to instantaneous error in the receiver's frequency tracking. The variation with frequency is a symptom of channel ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2.3 Interpolation | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2.3.1 Limitations | In principle, channel variations within the Nyquist supported area described in the previous clause can be measured. However, the Nyquist limit can only be very closely approached when using an interpolator having a very large number of taps. This is unattractive on grounds of cost and complexity, but is also bounded b... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2.3.2 Temporal interpolation | The presumption is that most receivers, on grounds of simplicity and minimising delay, will use at most simple linear temporal interpolation. To begin with we will consider simplest case of interpolation between scattered pilots. In DVB-C2 both of two scattered pilot patterns have Dy=4. It follows that simply to perfor... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.5.2.3.3 Frequency interpolation | Fortunately the frequency interpolator can use rather more taps. This is in fact necessary, since the 'time-width' (an analogous term, for frequency-domain sampling, to the common use of bandwidth in relation to time-domain sampling) of the interpolator now has to be an appreciable fraction of the Nyquist limit. Depend... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.6 Tuning to a Data Slice | As soon as the receiver performed all initial synchronization tasks (i.e. being synchronized in time, frequency and C2 framing) it can be tuned to the Data Slice where the required PLP is embedded. This clause illustrates the needed steps and provides two simple examples. ETSI ETSI TS 102 991 V1.2.1 (2011-06) 115 Durin... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.7 Buffer Management | NOTE: Clause 7.5 of the present document includes refinements of annexes C and G of the specification which will appear as a non-editorial update in the specification in the future. Thus, the explanations stated in this clause will refer to clause 7.5 instead of the current versions of the specification. In the course ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.8 DVB-C2 FECFrame Header Detection | |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.8.1 Overview of FECFrame Header Detection | The receiver needs to detect the FECFrame Header which is inserted in front of one or two FECFrames to support Adaptive Coding and Modulation (ACM). The FECFrame Header carries information of the PLP_ID, the Coding and Modulation parameters of the following FECFrame, and the number of FECFrames following the informatio... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.8.2 FECFrame Header Detection | The application of the robust or the high efficiency FECFrame header is signalled within the Layer 1 - Part 2 signalling. Here, we take robust FECFrame header as an example. The FECFrame header detection can be performed by the following steps: 1) Assume that the 32-symbol complex sequence (s0, s1,…, s31) = (ri, ri+1,…... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.8.3 Alternative FECFrame Header Detection | The DVB-C2 preamble does not signal the start of the Data Slice Packets for the Data Slice Type 2. Hence, the preamble has to provide the synchronisation capabilities on its own. This aim is reached by means of the transmission of the signalling data on the I- and Q-axes of the QPSK diagram (similar for 16-QAM) and the... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.9 LDPC Decoding | The most general decoding algorithm of LDPC code is an iterative message passing algorithm called belief propagation [i.13]. This algorithm is naturally suitable for parallel message computation. The structure of the parity check matrices of the LDPC codes adopted in DVB-C2 implies a partly-parallel decoder architectur... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.11.1.1 Construction of output TS | Construction of the output TS will make use of the following pieces of information: • SYNCD, SYNC and UPL: Used to regenerate the user packets (where applicable). See clause 10.11.1.2. • DNP: used to re-insert the null packets which were deleted in the modulator (see clause 10.11.1.5). • ISCR: used to calculate the out... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.11.1.2 Mode adaptation | Given the decoded baseband frames from the BCH decoder (see clause 10.10), the receiver should partially reverse the process of mode adaptation and so recover the payload data of the targeted service. The receiver should first determine whether Normal or High Efficiency Mode is being used. This is indicated by performi... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.11.1.3 Determination of output-TS bit-rate | The receiver needs to know the exact bit-rate of the output Transport Stream, in order to be able to output the stream. If ISSY is used, this can be calculated from the ISCR values. Following null-packet re-insertion, the bit stream will consist of a sequence of TS packets, some of which will have associated ISCR value... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.11.1.4 De-jitter buffer | The de-jitter buffer itself can be implemented using a FIFO more or less as described in annex C of [i.1]. The ISCR values are carried in the BBHeader; they are therefore prone to bit errors. The CRC allows bit errors to be detected, and when this happens the receiver should provide a "flywheel" mechanism to generate t... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.11.1.5 Re-insertion of deleted null packets | Conceptually, the deleted null packets are re-inserted before the de-jitter buffer as illustrated in annex G of [i.1]. The de-jitter buffer would then consist of a simple FIFO as shown. In practice, for reduced memory consumption, the deleted null packets may be re-inserted at the output of the de-jitter buffer. This c... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 10.11.1.6 Re-combining the Common and Data PLPs | When a particular input TS has been split and is sent in a data PLP and a common PLP, the original TS can be in principle recreated in the receiver by combining the contents of the data PLP and the common PLP, with the limitations given in annex D of [i.1] and described in this clause. The operations required to re-com... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 11 Theoretical Performance | This clause presents simulation results indicating the performance of DVB-C2 in a range of cable channels [i.15]. The results are based on the simulation and validation effort carried out during and following the development of the DVB- C2 standard [i.1]. The following information will be presented: • description of th... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 11.1 Channel Models | During the development of the DVB-C2 specification [i.1], different channel models have been used to provide simulated performance results. The channels have been chosen to verify the performance in a wide range of reception conditions. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 11.1.1 Additive White Gaussian Noise (AWGN) | In this channel model only white Gaussian noise (AWGN) is added to the signal, and there is only one path. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 11.1.2 Echo Channel | This model includes two cases of an echo distribution based on the HFC Channel Model as in [i.20] with adapted delay values, the second case being defined as a worst case scenario. The model is defined by ( ) ( ) i N i jθ i τ t ρ k t i − = ∑ = − x e y 1 where • ( )t x any ( )t y are input and output signals, respective... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 11.2 Simulated System Performance | Table 20 shows the simulated performance, assuming perfect channel-estimation, perfect synchronization and without phase noise, of channel coding and modulation combinations, and are subject to confirmation by testing. Results are given for the Gaussian channel and the echo channel. To keep simulation times reasonable,... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 11.2.1 Performance of L1 signalling part 2 over an AWGN channel | Simulation was done to analyze the coded performance of L1 signalling part 2 over an AWGN channel. By using the shortening and puncturing procedures described in clause 8.4.5, the L1 signalling bits are first BCH-encoded, and then the BCH encoded bits are LDPC-encoded. Note that the 16K LDPC code with effective code-ra... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 11.2.2 Correction values for pilot boosting | The values of required (C/N)0 given in table 20 are raw and do not taken into account the reduction in data C/N resulting from the presence of boosted pilots, since this depends on the pilot pattern in use, i.e. the actual Guard Interval length. Net values of C/N can be derived from the raw values (C/N)0 by computing a... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12 Examples of Possible Use of the System | The examples described below present practical implementation scenarios which should demonstrate the plurality of functionalities the DVB-C2 standard [i.1] supports including applications for multiplexing of PLPs and Data Slices, PLP bundling, adaptive/variable coding, and modulation etc. Although the DVB-C2 physical l... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1 Network Scenarios | The network scenarios introduced hereafter explain how DVB-C2 can be implemented to support different kind of signal processing (so called transmodulation) from satellite and terrestrial networks to cable. Furthermore it is explained how the new technology could be introduced in cable networks and how the migration fro... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.1 Methods of signal conversion in cable headends | This clause describes methods of signal processing, which are typically implemented in regional cable headends applying the conversion of satellite signals into - in this case DVB-C2 based - cable signals. Two scenarios are subsequently introduced: (see clause 12.1.1.1) the general scenario of an efficient and very fle... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.1.1 Efficient signal conversion from satellite or terrestrial link to DVB-C2 | This clause describes how signals which are received at a headend either via DVB-S or DVB-S2 transponders or via DVB-T or DVB-T2 channels or via any combination of both can be converted efficiently to a DVB-C2 signal. Table 21 shows relevant technical parameters of an example for a conversion of six DVB-S2 satellite si... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.1.2 Transparent signal conversion and MPEG2 Transport Stream processing | A very typical scenario which is currently implemented with DVB-C systems arranges for a complete and transparent signal conversion without any MPEG2 Transport Stream processing applied between receiver and transmitter unit. The transparent conversion can easily be achieved by replacing the DVB-C transmitter unit by a ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.1.3 Example for a configuration with a narrowband notch within a DVB-C2 signal | This example gives the signalling parameters of DVB-C2 signal with a narrowband notch, where those subcarriers which transmit the preamble symbols and which are located in the range of the narrowband notch are switched off. In such a configuration the notch weakens the error protection of the preamble as the informatio... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.1.4 Example for a configuration with a broadband notch within a DVB-C2 signal | This example gives the signalling parameters of DVB-C2 signal with two broadband notches , which takes into account the protection of two wireless BOS services located in the frequency ranges of 443,59375 - 444,96875 MHz and 448,59375 - 449,96875 MHz (example from Germany according to figure 87 in clause 12.1.6). The p... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.4 Video On Demand and other applications of personalized services | VOD services are 'unicast-type' of services, as a customer is requesting an individual communication link between the VOD server and his VOD enabled CPE. Therefore VOD services could be delivered via cable networks by means of both transmission systems DVB-C and DVB-C2, either using them separately or in parallel. The ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.5 Utilization for interactive services (IPTV, Internet) | The flowing system explanations are based on the simplified block diagram depicted in figure 76 which shows two basic downstream delivery scenarios for interactive services implemented in the last mile of a cable network. The first scenario describes an IP delivery via the DVB-C2 downstream pipe, which is operated in p... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.5.1 Example for IP transmission | Below a more detailed IP transmission example is shown. ETSI ETSI TS 102 991 V1.2.1 (2011-06) 142 In a 32 MHz channel the maximum transmission capacity for 1 024-QAM and code rate 8/9 is: s Mbit us R / 3. 269 (448/449) * 0.99 * (95/96) * 400) 232/14 (14 * (8/9) * (128/129) * 10 448 * 336 14 160 14 = = (3). Where the ma... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.5.2 Recommendations for arrangement of PLP's and data slices. | The following description gives a guidance how PLP's and data slices may be arranged dependent on the conditions within a certain cable network. |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.5.2.1 Robust mode | In this mode Data Slice width should be as high as possible (upper limit 7,61 MHz) to support optimal frequeny deinterleaver performance in the receiver. The reason for that is that frequency interleaving is only performed within a Data Slice but not within the whole C2 channel. In case of rather discrete disturbances ... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.5.2.2 High Efficiency mode | Where level of discrete interferences within a Data Slice can be neglected, this mode should chosen. In this mode for every input stream /PLP a single Data Slice is foreseen (see figure 81). Buffer overhead must be foreseen only once for the complete C2 channel. This buffer overhead is always in the range of the necess... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.5.3 Adaptive Coding and Modulation (ACM) | Cable networks with bi-directional communication capabilities allow the implementation of variable coding and modulation for the purpose of adapting the parameters for these elements in accordance with the channel conditions such as the CNR value occurring at a dedicated user outlet. This feature is referred to as Adap... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.5.4 PLP bundling | PLP bundling allows the transmission of a high bit rate stream. The bit rate per PLP is limited by the maximum Data Slice bandwidth of 7,61 MHz. By bundling of several PLPs and Data Slices, respectively, payload capacity can be significantly increased. The following example is given to elaborate this application in mor... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.1.6 Handling of Interference scenarios | In several countries different frequency bands used in cable networks are allocated for radio service as well, including safety related services such as air traffic control. For this reason, interference scenarios, both cable signals interfering radio services and terrestrial services interfering cable signals are disc... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.2 Migration Scenarios | The introduction of DVB-C2 requires the implementation of a migration strategy which allows continuing the transmission of traditional signals for a dedicated period of time. The strategies may differ among cable operators since they are based on many aspects and thus a general all-embracing migration cannot be discuss... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.2.1 From fixed to flexible channel raster | During transition from traditional transmission systems such as analogue TV and DVB-C to the new technology, DVB-C2 will have to coexist in a cable network side by side with analogue TV- and DVB-C/DOCSIS signals. This requirement has an impact on certain DVB-C2 parameters selected for a DVB-C2 transmission such as powe... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.2.2 Power level aspects | In addition to the flexible bandwidth allocation explained in the last clause, the correct adjustment of power levels is an important aspect to be considered for the introduction of DVB-C2. Two contradicting requirements have to be taken into account to identify the optimal power level for a signal. 1) The entire netwo... |
68c0023631b9916756c4eab7052aaa7b | 102 991 | 12.2.3 Non-backward compatibility to DVB-C | The signal processing defined by the DVB-C2 standard does not provide any backward compatibility with DVB-C. A related commercial requirement was not agreed in the DVB Commercial Module. In fact, the lack of backward compatibility was accepted in order to allow the exploitation of the full potentials provided by the st... |
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