hash stringlengths 32 32 | doc_id stringlengths 7 13 | section stringlengths 3 121 | content stringlengths 0 2.2M |
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92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.3.3.4 Remote Access Date Flag (immediate) | If the remote_access_date_immediate_flag is asserted then Remote Access of the entire Content Item is allowed, in accordance with other USI fields, starting when the absolute date specified in the remote_access_date Field matches the current date. ETSI ETSI TS 102 825-3 V1.2.1 (2011-03) 19 |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.3.3.5 Remote Access Date Field | The remote_access_date field specifies an absolute date and time after which Remote Access to Content is enabled. Remote Access can be enabled immediately for whole Content or on a moving window basis. Table 5: Interpretation of remote_access_date …_date_immediate_flag …_moving_window_flag remote_access_date interpreta... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.3.4 Proximity-based Propagation Control | |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.3.4.1 Local Movement and Copying Enabled (MLocal) | If asserted, Moving and/or Copying to another Storage Entity (or via a CPCM Device) is allowed if the Destination is Local to the Source, e.g. both within the same home, subject to the states of the CCI field. If not asserted, then this field carries no meaning and Movement and Copying Propagation is controlled exclusi... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.3.4.2 Local Viewing Enabled (VLocal) | If asserted, viewing, i.e. Consumption, using a Consumption Point (or via a CPCM Device) is allowed, if the Consumption Point (or CPCM Device) is Local to the Source, e.g. both within the same home, subject to the states of the V, VWA, View Window, SVCA and simultaneous_view_count fields. If not asserted, then this fie... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4 Output Control | |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.1 Controlled Export/Output | |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.1.1 Export/Output Control to Controlled CPS | Controlled Export/Output is the digital output of CPCM Content mapped to a Controlled CPS under the explicit control of the USI of that CPCM Content. Such output is either: a) Export of Content to a Controlled CPS; or b) Output of Content via a digital Consumption Output to a Controlled CPS. If export/output_controlled... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.1.2 Controlled CPS Vector | The controlled_CPS_vector identifies Controlled CPSs to which Export or Output is allowed for a particular C&R regime. |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.2 Untrusted Export | If export_beyond_trust is asserted, Content may be Exported to an Untrusted Space. If export_beyond_trust is not asserted, Content shall not be Exported to an Untrusted Space. NOTE: An Untrusted Space is any system, entity, device, component, medium, function, interface or any other tangible or intangible thing other t... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.3 Disable Analogue SD Export | If disable_analogue_SD_export is asserted, then Analogue Export of CPCM Content in Standard Definition analogue form is prohibited. If disable_analogue_SD_export is not asserted, then Analogue Export of CPCM Content in Standard Definition analogue form is permitted. |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.4 Disable Analogue SD Consumption | If disable_analogue_SD_consumption is asserted, then Analogue Consumption Output of CPCM Content in Standard Definition analogue form is prohibited. If disable_analogue_SD_consumption is not asserted, then Analogue Consumption Output of CPCM Content in Standard Definition analogue form is permitted. |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.5 Disable Analogue HD Export | If disable_analogue_HD_export is asserted, then Analogue Export of CPCM Content in High Definition analogue form is prohibited. If disable_analogue_HD_export is not asserted, then Analogue Export of CPCM Content in High Definition analogue form is permitted. |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.6 Disable Analogue HD Consumption | If disable_analogue_HD_consumption is asserted, then Analogue Consumption Output of CPCM Content in High Definition analogue form is prohibited. If disable_analogue_HD_consumption is not asserted, then Analogue Consumption Output of CPCM Content in High Definition analogue form is permitted. ETSI ETSI TS 102 825-3 V1.2... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.4.7 Image Constraint | If image_constraint is asserted, then Content output to High Definition analogue Outputs or Content Exported to an Untrusted Space must first pass through a Processing operation that constrains the resolution of the image portion of the Content to a visual equivalent of no more than 520,000 pixels per frame (e.g. an im... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.5 Ancillary Control | |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 6.5.1 Do Not CPCM Scramble (DNCS) | If DNCS is asserted, CPCM Content shall not be scrambled by the CPCM Scrambler. If DNCS is not asserted, this field carries no meaning. NOTE 1: The assertion of DNCS does not imply any relaxation of the enforcement of other associated USI; however, it is anticipated that DNCS may not be asserted with certain combinatio... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 7 CPCM Auxiliary Data | |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 7.1 General | CPCM Auxiliary Data has the same general characteristics and requirements as USI: • it is CPCM Content metadata that may be used along with USI to signal Authorized Usage for that particular Content Item; • it is securely bound to the Content Item; • it is determined and preserved upon Acquisition; and • it may be used... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 7.2 CPCM Auxiliary Data for Original USI Maintenance | Within CPCM USI, some USI may change upon Content Usage (see clause 4.5). The goal of these auxiliary data is to maintain the original USI signalling upon Content Acquisition. CPCM Auxiliary Data for Original USI maintenance can have two forms: • Maintenance of original signalling associated with a Free-To-Air content.... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 7.3 CPCM Auxiliary Data for Geographic Area Definition | The Geographic Area in which propagation is allowed by MGAD and/or VGAD is carried in geographic_area data structure. The overall Geographic Area is expressed as up to 256 sets of geo_data structures, which allows multiple methods of encoding for same or similar areas. Propagation is allowed, in accordance with other U... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 7.4 CPCM Auxiliary Data for Export/Output to Trusted CPS | A private data structure reserved for future use that may be used to carry, for example, data unique to each Trusted CPS. Detailed definition of this data field and conditions for its use are: 1) beyond the scope of this multi-part deliverable; 2) may require further description in other DVB specifications and/or a C&R... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 7.5 CPCM Auxiliary Data for Export/Output to Controlled CPS | A private data structure reserved for future use that may be used to carry, for example, data unique to each Controlled CPS. 1) Detailed definition of this data field and conditions for its use are defined by each C&R regime. |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 7.6 CPCM Auxiliary Data for Analogue Protection Systems | A private data structure to provide control signals to analogue output protection systems. NOTE: Some Content may include this signalling to enable certain analogue protection systems on analogue outputs. At the time this multi-part deliverable was drafted, two different systems existed for standard definition outputs ... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 8 Syntax of USI and CPCM Auxiliary Data | |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 8.1 CPCM USI Syntax | Table 6 gives the syntax of CPCM USI. Table 6: CPCM USI Syntax Bits Identifier CPCM_usage_state_information(){ length 8 uimsbf copy_control 3 uimsbf do_not_cpcm_scramble 1 bslbf viewable 1 bslbf view_window_activated 1 bslbf view_period_activated 1 bslbf simultaneous_view_count_activated 1 bslbf move_local 1 bslbf view... |
92646f4b2a91a814e0eb35e493c92b0c | 102 825-3 | 8.2 CPCM Auxiliary Data Syntax | The CPCM auxiliary data syntax is shown in Table 10. CPCM auxiliary data structure is securely bound to the CL but shall be transported independently as specified in TS 102 825-9 [3]. Table 10: CPCM Auxiliary Data structure Syntax Bits Identifier CPCM_auxiliary_data(){ CPCM_auxiliary_data_element_counter 8 uimsbf for (... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 1 Scope | The present document gives guidelines for the implementation of all aspects of the DVB-T2 end-to-end chain. This includes: • the parts of the system defined by the physical layer system specification [i.1]; • aspects of the input pre-processing, which is outside the scope of [i.1]; • the modulator interface (or T2-MI) ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 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 ar... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 2.1 Normative references | The following referenced documents are necessary for the application of the present document. Not applicable. |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 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 302 755: "Digital Video Broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital terrestrial televisi... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 3 Definitions, symbols and abbreviations | |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 3.1 Definitions | For the purposes of the present document, the terms and definitions given in EN 302 755 [i.1] and the following apply: allocation window: period during which the last bit of a BBFRAME can arrive and that BBFRAME be allocated to a given interleaving frame basic T2-Gateway: device taking one input stream per data PLP and... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 3.2 Symbols | For the purposes of the present document, the symbols given in EN 302 755 [i.1] and the following apply: Cbias Total complex bias in the modulated cells of the L1 signalling (i.e. the complex sum of the cells) Cbias_residual Total expected residual bias in the P2 symbols after adding any bias balancing cells CTR The ex... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 3.3 Abbreviations | For the purposes of the present document, the abbreviations given in EN 302 755 [i.1] and the following apply: 1PPS One-pulse-per-second (signal from GPS receiver or other timing reference) ACE Active Constellation Extension AGC Automatic Gain Control ASI Asynchronous Serial Interface AWGN Additive White Gaussian Noise... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4 Overview of DVB-T2 | |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.1 Commercial requirements overview | The DVB organisation defined a set of commercial requirements which acted as a framework for the T2 developments. These commercial requirements included: • T2 transmissions should be able use existing domestic receive antenna installations and should be able to re-use existing transmitter infrastructures. (This require... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.2 Background design principles | A few general principles were adopted in the design of T2. These were: a) The DVB organisation should aim to provide a coherent family of standards where possible. b) Translation between DVB standards (for example, between DVB-S2 and DVB-T2) should be as easy as possible. c) T2 should not re-invent solutions if they al... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.3 Benefits of DVB-T2 compared to DVB-T | As a result of the technologies introduced in DVB-T2, the potential gain in capacity that could be achieved in the UK was expected to be nearly 50 % compared to the pre-switchover UK mode of DVB-T (see table 1). In addition to the increased capacity, the proposed DVB-T2 mode was expected to offer greater tolerance of m... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.4 System overview | |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.4.1 Introduction | This clause gives a brief overview of the second-generation digital terrestrial broadcasting system (DVB-T2), designed to meet all of the commercial requirements given in clause 4.1. The complete DVB-T2 system has at its heart a draft physical-layer specification [i.1]. However, this physical-layer specification is onl... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.4.2 Architectural model | The top-level block diagram of a reference DVB-T2 end-to-end chain is shown in figure 1 for the Transport Stream case. Figure 1: Block diagram of DVB-T2 chain The full DVB-T2 system can be divided into three basic sub-systems on the network side (SS1, SS2 and SS3) and two sub-systems on the receiver side (SS4 and SS5).... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.4.3 Specification documents describing DVB-T2 | The DVB-T2 system is described by the following standards: • EN 302 755 [i.1], Frame structure channel coding and modulation for a second generation digital terrestrial television broadcasting system (DVB-T2). EN 302 755 [i.1] defines the physical layer of the DVB-T2 signal on air. • EN 300 468 [i.14], Service Informat... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.4.4 Physical-layer specification | The generic model for the DVB-T2 physical layer (T2) is represented in figure 3. The system input may be one or more MPEG Transport Stream(s) and/or one or more Generic Stream(s). These may have been modified, where appropriate, by the pre-processing in the T2 Gateway, such that by this point in the chain, the stream i... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.4.5 Additional sources of assistance for implementers | In addition to the present document and the specification documents mentioned in clause 4.4.3, there are two other sources of assistance for implementers of DVB-T2: • The DVB-T2 reference streams [i.26], also known as the V&V (Validation and Verification) streams. These are a set of files describing the signals at ever... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5 Key technologies | This clause presents an introduction to the technologies used in DVB-T2, particularly those which were not used in DVB-T. |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.1 Physical Layer Pipes (PLPs) | The commercial requirement for service-specific robustness together with the need for different stream types is met by the concept of fully transparent physical-layer pipes (figure 4), which enable the transport of data independently of its structure, with freely selectable, PLP-specific physical parameters. Both the a... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.1.1 Input Mode A | This most simple mode can be viewed as a straightforward extension of DVB-T employing the other advanced features outlined in this clause, but not being sub-divided into multiple PLPs. Here only a single PLP is used, transporting a single transport stream. Consequently the same robustness is applicable to all content, ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.1.2 Input Mode B | This more advanced mode of operation applies the concept of multiple physical-layer pipes (figure 5). Beside the advantage of service-specific robustness, this mode offers potentially longer time-interleaving depth as well as the option of power saving in the receiver. Therefore even in the case of identical physical-p... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.2 Additional bandwidths (1,7 MHz and 10 MHz) | In order to make DVB-T2 also suitable for professional use, e.g. transmissions between radio cameras and mobile studios, a 10 MHz option is included; consumer receivers are not expected to support the 10 MHz mode. To allow DVB-T2 to be used in narrower RF channel assignments in e.g. band III and in the L-band, the band... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.3 Extended carrier mode (for 8 K, 16 K, 32 K) | Because the rectangular part of the spectrum rolls off more quickly for the larger FFT-sizes, the outer ends of the OFDM signal's spectrum can be extended, i.e. more sub-carriers per symbol can used for data transport. The gain achieved is between 1,4 % (8 K) and 2,1 % (32 K). Figure 6 compares the spectrum for 2 K wit... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.4 Alamouti-based MISO (in frequency direction) | Although DVB-T supports Single-Frequency Networks (SFNs), the presence of similar-strength signals from two transmitters in a network causes a significant loss of margin because the resulting channel can have deep "notches". There is evidence from the field that portable reception can suffer as a result and requires a ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.5 Preambles (P1 and P2) | The initial symbols of a DVB-T2 physical-layer frame are preamble symbols, transporting a limited amount of signalling data in a robust way. The frame starts with the highly robust differentially BPSK-modulated P1 symbol, with guard intervals at both ends, which carries 7 bits of information (including the FFT size of ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.6 Pilot patterns | Scattered pilots of pre-defined amplitude and phase are inserted into the signal at regular intervals in both time and frequency directions. They are used by the receiver to estimate changes in channel response in both time and frequency dimensions. Whereas DVB-T applies the same static pattern independent of the FFT s... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.7 256-QAM | In DVB-T the highest-order constellation is 64-QAM, delivering a gross data rate of 6 bits per symbol per carrier (i.e. 6 bits per OFDM cell). In DVB-T2, the use of 256-QAM (figure 9) increases this to 8 bits per OFDM cell, a 33 % increase in spectral efficiency and capacity transported for a given code rate. Normally ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.8 Rotated constellations | A new technique of constellation rotation and Q-delay has been introduced in DVB-T2. After forming a constellation, it is rotated in the complex "I-Q" plane so that each axis on its own (u1, u2) now carries enough information to tell which of the points was sent (figure 10). Figure 10: Rotated 16-QAM constellation The ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.9 16 K and 32 K FFT sizes and 1/128 guard-interval fraction | Increasing the FFT size results in a narrower sub-carrier spacing, but longer symbol duration. The first attribute leads to greater difficulties with inter-carrier interference, hence lower Doppler frequency that can be tolerated. Whilst this is not a setting preferred for mobile reception in UHF band IV/V or higher, i... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.10 LDPC/BCH error control coding | Whereas inner and outer error-control coding in DVB-T was based on convolutional and Reed-Solomon codes, ten years of technological development mean that the higher complexity of LDPC decoding can now be handled in the receiver. DVB-T2 uses concatenated LDPC/BCH coding, as for DVB-S2. These codes assure a better protec... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.11 Interleaving stages (time, bit, cell, frequency) | The target of the interleaving stages is to spread the content in the time/frequency plane in such a way that neither impulsive noise (disturbance of the OFDM signal over a short time period) nor frequency-selective fading (disturbance over a limited frequency span) would erase long sequences of the original data strea... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.12 Peak-to-Average Power Ratio (PAPR) reduction techniques | High PAPR in OFDM systems can reduce RF power-amplifier efficiency, i.e. RF power out versus supply power in. Two PAPR-reduction techniques, Active Constellation Extension (ACE) and Tone Reservation (TR) are supported in DVB-T2, leading to a substantial reduction of PAPR, at the expense of a small average-power increme... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.5.13 Future Extension Frames (FEFs) | In order to build a hook into the original DVB-T2 standard for future advancements such as MIMO or a fully mobile branch of the standard, a placeholder known as Future Extension Frame (FEF) parts is included. The common attributes of all FEF parts, which are inserted between T2-frames (see figure 14), are that they beg... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.6 Memory and complexity considerations | The DVB-T2 standard has been designed to provide a compromise between receiver complexity and performance of the system. Memory requirements in the receiver are discussed in various parts of the present document. The most significant memory requirement arises in the Time De-Interleaver, which has around 500 000 cells. ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.7 Layer 2 signalling | |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.7.1 Overview | 4. |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 7.1 Overview | The DVB-T2 physical layer provides a number (up to 255 - depending on the FFT size and L1 coding parameters) of transparent Physical-Layer Pipes (PLPs) to the layers above. These PLPs are characterized by the following attributes: • Constellation (QPSK, 16-QAM, 64-QAM or 256-QAM). • Code rate (1/2, 3/5, 2/3, 3/4, 4/5, ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.7.2 T2 delivery-system descriptor | Following the same principles as the existing terrestrial-delivery-system descriptor for DVB-T, this new descriptor for DVB-T2 also provides the signalling for the co-existence of several Transport Streams within the same multiplex (using PLPs). The T2 delivery-system descriptor achieves this by mapping a Transport Str... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.8 Network Topology and Modulator Interface (T2-MI) | Unlike in DVB-T, where a single Transport Stream is carried in a single RF channel, in DVB-T2 there is a degree of flexibility in how the data for each PLP is allocated to the T2-frame; the T2 specification merely requires that certain constraints be met. To enable Single Frequency Network (SFN) operation, decisions on... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 4.9 Transmitter identification | Proposals for techniques to assist with transmitter identification are currently being considered. More details will be given in future editions of the present document. |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5 Choice of parameters | There are a large number of ways of configuring a DVB-T2 system, and this clause will discuss the choice of each of the main parameters in turn. |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.1 Choice of FFT size | The factors affecting the choice of FFT size are well known. Increasing the FFT size will give a greater delay tolerance for the same fractional guard interval, allowing larger Single Frequency Networks (SFNs) to be constructed. Alternatively, larger FFTs allow the same delay tolerance to be achieved with a smaller ove... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.2 Choice of extended or normal carrier mode | The DVB-T2 signal has been designed so that it should not present more stringent requirements in frequency planning than DVB-T. In many cases, this even remains true when the so-called extended-carrier mode is in use. The spectrum of a 'classical' guard-interval-OFDM signal exhibits a more-or-less rectangular spectrum ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.3 Choice of Guard interval | DVB-T2 offers a wide range of possible guard intervals in order to support a range of broadcasters' needs. We should distinguish two concepts: • the guard-interval duration TG ; and • the guard-interval fraction GIF = TG TU . The former has the dimensions of time and the latter is dimensionless. The simplest view is to... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.4 Choice of pilot pattern | With the exception of one usage scenario (explained later), a DVB-T2 receiver makes measurements of the channel using Scattered Pilots (SPs) and then interpolates between these measurements to construct estimates of the channel response for every OFDM cell (see clause 10.3.2.3). The measurements need to be sufficiently... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.5 Choice of frame length | The T2-frame length, i.e. the number of symbols LF in a T2-frame, is a configurable parameter and can be chosen as required by the broadcaster or network operator. There are three constraints imposed by [i.1]: • The maximum T2-frame duration is 250 ms. This enables the receiver to know definitively after this amount of... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.6 Choice of superframe length | The minimum superframe length is 2 frames, and in many cases, including in Input Mode A, there will be no reason to choose a longer superframe length than this. Longer superframes may be needed if: • multi-frame interleaving is used (i.e. PI>1) for some PLPs; or if • PLPs use the "frame skipping" mechanism (i.e. Ijump>... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.7 Choice of input mode (A or B) | There are two basic input modes for single-RF operation: Input Modes A and B. Input Mode A takes a single Transport Stream (or Generic Stream) of constant total bit-rate. The Transport Stream may contain a number of services, possibly statistically multiplexed together. In Input Mode B, the T2 system carries more than ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.8 Choice of number of sub-slices | Increasing the number of sub-slices increases the time diversity of each PLP. A large number of sub-slices also results in a more even delivery of data throughout the T2 frame, making management of the de-jitter buffer and time-de-interleaver memory easier. In general, therefore, the number of sub-slices should be as l... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.8.2 Subslicing with multi-frame interleaving | When Type 2 PLPs are interleaved over multiple frames, i.e. when PI > 1, the number of time interleaver rows per FEC block has to be divisible by Nsubslices × PI, the total number of subslices into which the Interleaving Frame will be divided. Nsubslices has to be chosen such that, for each PLP using multi-frame interl... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.9 Choice of time interleaving parameters | The choice of number of TI blocks per Interleaving Frame depends on two factors. Increasing the number of TI blocks for a given frame duration reduces the interleaving time, so reducing the time diversity and therefore the system's resistance to impulsive interference and fast time-varying channels. On the other hand, ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.9.1 Trade-off between Time Diversity and Data Rate | In order to perform time de-interleaving, DVB-T2 receivers have to store the incoming OFDM cells during the transmission of a complete TI-block before they can de-interleave and process the FEC blocks. As a result, the interleaving duration is limited by the service data rate and the size of the TI memory. This has bee... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.9.2 Trade-off between Time Diversity and Latency | In DVB-T2, receivers have to wait until the complete reception of one TI block before they can de-interleave and process the FEC blocks. The longer the interleaving duration, the longer the receivers will have to wait prior to the de-interleaving of the TI blocks. With a single PLP, the interleaving duration is around ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.9.3 Trade-off between Time Diversity and Power Saving | DVB-T2 receivers can switch off some of their circuitry during the periods of time between time slices in order to reduce power consumption. From a power saving point of view, each PLP should be transmitted in a single time slice of information per T2-frame. The main reason for this is that due to synchronization and c... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.10 Choice of rotated constellations | This technique improves the robustness of the receiver to severe channel conditions. However, it cannot be used together with the ACE PAPR reduction technique. Rotated constellations give maximum gain when used with low constellation sizes (such as QPSK) and higher code rates. Conversely, the gain is much reduced for h... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.11 Choice of code rate, block length and constellation | The principles affecting choice of code-rate and constellation are similar to those in DVB-T. Higher code-rates and higher-order constellations both give greater bit rates but require higher signal-to-noise ratios. However, it should be noted that the performance of LDPC codes is significantly better than convolutional... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 5.12 Choice of mode adaptation options | There are a number of options for mode adaptation, described in clause 5.1 of [i.1]: • Normal Mode (NM) or High Efficiency Mode (HEM). • Use of Input Stream Synchronisation (ISSY). • Use of Null Packet Deletion (NPD). It is recommended that the options be used as follows: • Where compatibility with DVB-S2 [i.17] is req... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6 Anatomy of the DVB-T2 signal | This clause will describe the various concepts involved in the DVB-T2 signal, and the relationship between them. In terms of framing structures, there is a basic division into the physical frame structure of superframes, T2-frames, and symbols; and what will be termed the logical frame structure of BBFRAMEs, Interleavi... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1 Physical frame structure | |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.1 Superframe | The largest entity of a DVB-T2 system is a super frame. A super frame carries T2-frames and may also carry Future-Extension Frame (FEF) parts as depicted in figure 22. The maximum number of T2-frames in a super frame is 255. The maximum length of a T2-frame is 250 ms and the maximum length of a FEF part is 250 ms. The ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.2 T2-frame | A T2-frame consists of a P1 symbol, NP2 P2 symbols and a configurable number of data symbols, of which the last can be a special frame closing symbol for some parameter combinations (see clause 6.1.2.1). The number of P2 symbols NP2 depends on the FFT size and is defined in table 7. ETSI ETSI TS 102 831 V1.2.1 (2012-08... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.2.1 Frame-Closing Symbols | In some combinations of FFT size, Scattered Pilot pattern and guard interval, the last symbol of the T2 frame is a special frame-closing symbol. This has a higher density of pilots in order to allow frequency-only interpolation to be used for the symbol itself, and temporal interpolation (as opposed to extrapolation) f... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.3 L1 signalling | The L1 signalling is divided into L1-pre signalling and L1-post signalling. The modulation and code rate of the L1-pre signalling is BPSK 1/2 and the number of signalling bits in L1-pre is constant. Thus, the L1-pre signalling always occupies 1 840 cells. The number of signalling bits in L1-post signalling depends on t... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.4 Physical-layer pipes | The physical-layer pipes (PLPs) carry the service data and signalling data for other layers than L1 (physical layer). The L1 signalling is carried separately from the PLPs as described above. Every PLP can have its own modulation, coding and time-interleaving length. ETSI ETSI TS 102 831 V1.2.1 (2012-08) 51 There are t... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.5 Dummy cells | The total number of active cells in a T2-frame available for PLPs depends in a complicated manner on many of the T2 system parameters and is not in general a multiple of Ncells, the number of cells in a FEC block. Since there have to be a whole number of FEC blocks in a T2-Frame (except for multi-frame interleaving), t... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.6 Auxiliary streams | The dummy cells do not carry useful information and therefore represent wasted capacity. In the future, applications may be defined which make use of these otherwise wasted cells, and the concept of an Auxiliary Stream is defined for this purpose. One application, Transmitter Signature [i.22], has already been defined.... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.7 FEFs | |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.7.1 FEF Basics | Future-Extension Frames (FEF) provide a method of expanding the DVB-T2 standard in the future by means and ways not known at the time of writing the original standard. This is done by inserting new additional periods known as FEF-parts between the normal T2-frames. Thus the FEF parts and T2-frames are separated in time... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.7.2 FEF Signalling | The use of FEFs is signalled both in P1 and in P2 symbols. The P1-symbol has two signalling fields S1 and S2. The S1 field is used to distinguish the preamble format and, hence, the frame type. If FEF parts are inserted in the T2-system, the P1 in the FEF parts will have a different S1 value than the in the T2 P1, for ... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.1.7.3 Possible use cases | Two uses of FEFs have already been defined: T2-Lite (see clause 16) and Tx-SIG (see clause 17). As the FEF is intended for future extensions of the system, it is impossible to describe the as-yet undefined use cases in detail, but some possibilities will be suggested here. The FEF-source can either be the T2-network or... |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.2 Logical frame structure | |
5c408ecfef3e523a192afe3fd7249eaf | 102 831 | 6.2.1 Packets | PLPs may carry packets, including MPEG Transport Stream packets or other types of packets used by generic streams. They may also carry continuous, non-packetised streams. The BBFRAME header (see clause 6.2.2.1) provides a mechanism for packets to be reconstructed at the receiver, but the framing of the DVB-T2 signal it... |
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