1、 ETSI TS 101 759 V1.2.1 (2005-01)Technical Specification Digital Audio Broadcasting (DAB);Data Broadcasting - Transparent Data Channel (TDC)European Broadcasting Union Union Europenne de Radio-Tlvision EBUUER ETSI ETSI TS 101 759 V1.2.1 (2005-01) 2 Reference RTS/JTC-DAB-33 Keywords audio, broadcasti
2、ng, DAB, data, digital, packet mode ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice Individual
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6、cept as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2005. European Broadcasting Union 2005. All rights reserved. DECTTM, PLUGTESTSTM and UMTSTM are Trade Marks of ETSI registered fo
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8、nts Intellectual Property Rights4 Foreword.4 Introduction 4 1 Scope 6 2 References 6 3 Abbreviations and syntax specification6 3.1 Abbreviations .6 3.2 Syntax specification .7 4 Transparent Data Channel specification.7 4.1 TDC in a packet mode service component.7 4.1.1 TDC in a packet mode service c
9、omponent without data groups.8 4.1.2 TDC in a packet mode service component with data groups9 4.2 TDC in a stream mode service component.10 4.3 TDC in an audio service component using X-PAD11 4.3.1 TDC in X-PAD without data groups 11 4.3.1.1 Using short X-PAD for the TDC.11 4.3.1.2 Using variable le
10、ngth X-PAD for the TDC.12 4.3.2 TDC in X-PAD with data groups12 5 Guidelines for the use of the Transparent Data Channel13 History 14 ETSI ETSI TS 101 759 V1.2.1 (2005-01) 4 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. T
11、he information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available f
12、rom the ETSI Secretariat. Latest updates are available on the ETSI Web server (http:/webapp.etsi.org/IPR/home.asp). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in E
13、TSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This Technical Specification (TS) has been produced by Joint Technical Committee (JTC) Broadcast of the European Broadcasting Union (EBU), Comit Europen de Normalis
14、ation ELECtrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI). NOTE 1: The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the specific field of broadcasting and related fields. Since 1995 the JTC Broadcast became a tripart
15、ite body by including in the Memorandum of Understanding also CENELEC, which is responsible for the standardization of radio and television receivers. The EBU is a professional association of broadcasting organizations whose work includes the co-ordination of its members activities in the technical,
16、 legal, programme-making and programme-exchange domains. The EBU has active members in about 60 countries in the European broadcasting area; its headquarters is in Geneva. European Broadcasting Union CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: +41 22 717 21 11 Fax: +41 22 717 24 81 The Eureka P
17、roject 147 was established in 1987, with funding from the European Commission, to develop a system for the broadcasting of audio and data to fixed, portable or mobile receivers. Their work resulted in the publication of European Standard, EN 300 401 1, for DAB (see note 2) which now has worldwide ac
18、ceptance. The members of the Eureka Project 147 are drawn from broadcasting organizations and telecommunication providers together with companies from the professional and consumer electronics industry. NOTE 2: DAB is a registered trademark owned by one of the Eureka Project 147 partners. Introducti
19、on The Transparent Data Channel (TDC) specification provides DAB with the ability to transport simple data streams using a variety DAB data channels. In a simple stream, data bytes are processed sequentially by the receiver in the order in which they are received but there is no implied beginning or
20、 end to the data. Any “framing“ of data within the stream is determined purely by the application protocol that is carried by the stream. Three forms of the Transparent Data Channel are specified here: TDC in a packet mode service component; TDC in a stream mode service component; TDC in an audio se
21、rvice component carried as X-PAD. ETSI ETSI TS 101 759 V1.2.1 (2005-01) 5 The Transparent Data Channel complements the MOT specification by allowing DAB to transport data in the form of streams as well as files. It is intended that applications that rely on simple stream transport, such as the TPEG
22、and DGPS protocols, can be supported in DAB simply by specifying the use of the Transparent Data Channel for data transport. The present document has removed the “byte stuffing“ mechanism previously defined for TDC carried as X-PAD as this was found to cause some decoding difficulties. In addition,
23、data groups may be used in X-PAD. ETSI ETSI TS 101 759 V1.2.1 (2005-01) 6 1 Scope The present document specifies how to transport data transparently within the Digital Audio Broadcasting (DAB) system forming a Transparent Data Channel (TDC) and gives guidelines for its use. 2 References The followin
24、g documents contain provisions which, through reference in this text, constitute provisions of the present document. 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
25、. For a non-specific reference, the latest version applies. Referenced documents which are not found to be publicly available in the expected location might be found at http:/docbox.etsi.org/Reference. 1 ETSI EN 300 401: “Radio Broadcasting Systems; Digital Audio Broadcasting (DAB) to mobile, portab
26、le and fixed receivers“. 2 ETSI TR 101 496 (all parts): “Digital Audio Broadcasting (DAB); Guidelines and rules for implementation and operation“. 3 ETSI EN 301 234: “Digital Audio Broadcasting (DAB); Multimedia Object Transfer (MOT) protocol“. 3 Abbreviations and syntax specification 3.1 Abbreviati
27、ons For the purposes of the present document, the following abbreviations apply: CCITT International Consultative Committee for Telegraph and Telephone CRC Cyclic Redundancy Check DAB Digital Audio BroadcastingF-PAD Fixed - Programme Associated Data MOT Multimedia Object Transfer MSC Main Service Ch
28、annel PAD Programme Associated Data TCP Transmission Control Protocol TDC Transparent Data Channel TPEG Transport Protocol Experts Group X-PAD eXtended - Programme Associated Data ETSI ETSI TS 101 759 V1.2.1 (2005-01) 7 3.2 Syntax specification The specifications of syntax that appear in the present
29、 document are written using a form of pseudo-code that is similar to the procedural language “C“; this provides for easy specification of loops and conditional data structures. Within these specifications, the type of individual data fields is expressed using the mnemonics given in table 1-1. Table
30、1-1: Data type mnemonics for syntax specification Mnemonic Description uimsbf Unsigned integer, most significant bit first bslbf Bit string, left bit first rpchof Remainder polynomial coefficients, high order first 4 Transparent Data Channel specification The MOT protocol allows transportation of ob
31、jects - this is achieved either by using simple MOT transport for non-ordered data objects or by using a data carousel for a managed set of data files. As a complement to this, the Transparent Data Channel allows simple stream data to be delivered to support stream based applications (for example TP
32、EG). The TDC specification described below is based on the mechanisms that are provided by EN 300 401 1 for data delivery: Packet mode service component. Data in an audio service Component using X-PAD. The implementation of these basic mechanisms is explained in more details in TR 101 496 2. 4.1 TDC
33、 in a packet mode service component TDC data carried in a packet mode service component may be organized either with or without the MSC data group structure defined by EN 300 401 1. The use of data groups for establishing a transparent data channel provides: Error control by using data group repetit
34、ion. The ability to guarantee that “chunks“ of data from the stream are delivered to the receiver (or lost) as a coherent sets of data. Optional addressing of end users. Where the features above are not required, not using data groups for the TDC provides: Low overhead. Low latency. Simple processin
35、g requirements. The two forms of the TDC in a packet mode service component are specified in the following paragraphs. ETSI ETSI TS 101 759 V1.2.1 (2005-01) 8 4.1.1 TDC in a packet mode service component without data groups Packet mode sub-channels use a simple packet protocol to allow a number of s
36、eparate data services to be multiplexed into a single DAB sub-channel. Carriage of simple stream data in such a channel is implemented by sending packets containing the data when there is data to send. The structure of DAB packets is shown in table 2-1. Table 2-1: Structure of a DAB packet Syntax Si
37、ze Type DAB_packet() packet_length 2 bits uimsbf continuity_index 2 bits uimsbf first_ flag 1 bit bslbf last_flag 1 bit bslbf packet_address 10 bits uimsbf command_flag 1 bit bslbf useful_data_length 7 bits uimsbf for (i=0;iuseful_data_length;i+) packet_data_byte 8 bits uimsbf for (i=0;iN;i+) paddin
38、g_byte 8 bits uimsbf packet_CRC 16 bits rpchof packet_length: This field can take one of four values to indicate the overall size of the packet in multiples of 24 bytes. The maximum length of the payload of each packet is equal to the overall packet length minus the 5 bytes of packet overhead. The o
39、verall packet length may be determined from the packet_length field by the formula (packet_length + 1) 24, thus a packet_length of 0 indicates an overall packet length of 24 bytes and a packet_length of 3 indicates an overall packet length of 96 bytes. continuity_index: The continuity_index is incre
40、mented by one for each successive packet that is sent for a particular packet_address. first_flag: The first_flag is used to indicate (when set to 1) that the packet is the first packet in a series of packets that are to be assembled into an MSC data group. last_flag: The last_flag is used to indica
41、te (when set to 1) that the packet is the last packet in a series of packets that are to be assembled into an MSC data group. packet_address: The packet_address is a 10 bit number that identifies packets for a particular data service component within the multiplex of components for a packet mode sub
42、-channel. useful_data_length: The useful_data_length field identifies the number of bytes within the payload of the packet that are to be considered to be carrying useful data. packet_data_byte: These fields carry the useful payload for each individual packet. padding_byte: The padding_bytes are use
43、d to fill the remainder of the packet after the packet_data_bytes and shall be set to 0. packet_CRC: The packet_CRC field is calculated, according to the CCITT CRC-16 polynomial, over the entire packet, with the CRC register initialized to all 1s and the resulting CRC inverted. Within a packet mode
44、sub-channel, packets may be assembled into larger, variable length datagrams known as MSC data groups. The assembly of packets into data groups is controlled by the first and last flags, as shown in table 2-2. ETSI ETSI TS 101 759 V1.2.1 (2005-01) 9 Table 2-2: Interpretation of first and last flags
45、first_flag last_flag Interpretation 0 0 The packet is an intermediate packet in a series of packets 0 1 The packet is the last packet in a series of packets 1 0 The packet is the first packet in a series of packets 1 1 The packet is the one and only packet In order to carry stream data in this very
46、simple way, the data is sent in packets with the first_flag and the last_flag both set to zero, thus indicating that the data carried by the packets is simply an intermediate part of a stream with no specific start or end. Marking the packets in this way ensures that no receiver will ever attempt to
47、 incorrectly assemble asynchronous stream data into data groups. The use of data groups in TDC depends upon the DG flag in FIG 0/3 (see EN 300 401 1). When set to 0, data groups are used, when set to 1 no data groups are used. 4.1.2 TDC in a packet mode service component with data groups In order to
48、 carry stream data, the data is put into a data group, which in turn is sent in packets. Table 2-3: Structure of an MSC data group Syntax Size Type MSC_data_group() MSC_data_group_header() extension_flag 1 bslbf CRC_flag 1 bslbf segment_flag 1 bslbf user_access_flag 1 bslbf data_group_type 4 uimsbf
49、continuity_index 4 uimsbf repetition_index 4 uimsbf if (extension_flag = 1) extension_field 16 bslbf session_header() if (segment_flag = 1) last 1 bslbf segment_number 15 uimsbf if (user_access_flag = 1) user_access_field () rfa 3 bslbf tranport_id_flag 1 bslbf length_indicator 4 uimsbf if (transport_id_flag = 1) transport_id 16 uimsbf end_user_address_field() for (n=0;nlength_indicator-2;n+) end_user_address_byte 8 uimsbf MSC_data_group_data_field() for (i=0;id
