1、 Rec. ITU-R BS.1547 1 RECOMMENDATION ITU-R BS.1547 Terrestrial component of systems for hybrid satellite-terrestrial digital sound broadcasting to vehicular, portable and fixed receivers in the frequency range 1 400-2 700 MHz (Question ITU-R 107/10) (2001) The ITU Radiocommunication Assembly, consid
2、ering a) that there is an increasing interest worldwide for terrestrial and satellite digital sound broadcasting (DSB) to vehicular, portable and fixed receivers in the frequency range 30-3 000 MHz for local, regional and national coverage; b) that the ITU-R has already adopted Recommendations ITU-R
3、 BS.774 and ITU-R BO.789 to indicate the necessary requirements for DSB systems to vehicular, portable and fixed receivers for terrestrial and satellite delivery, respectively; c) that by operating the broadcasting-satellite service (BSS) (sound) in an hybrid configuration the service objectives lis
4、ted in b) above can be more adequately met; d) that Recommendations ITU-R BS.774 and ITU-R BO.789 recognize the benefits of complementary use of terrestrial and satellite systems, and call for a DSB system allowing a common receiver with common processing very large scale integration (VLSI) circuits
5、 and manufacturing of low-cost receivers through mass production; e) that Digital System DHdescribed in Annex 2 meets most or all of the requirements of Recommendations ITU-R BS.774 and ITU-R BO.789, and that the system has been field tested and demonstrated in more than one country; f) that Digital
6、 System E described in Annex 3, meets most or all of the requirements of Recommendations ITU-R BS.774 and ITU-R BO.789, and that it has been field tested; g) that some systems included in Recommendation ITU-R BO.1130 have a terrestrial component which allows augmentation of the BSS (sound) part, hen
7、ce creating a hybrid satellite/terrestrial system; h) that at the 7th World Conference of Broadcasting Unions (Mexico, 27-30 April 1992), the World Broadcasting Unions unanimously resolved (literal quote): “1. that efforts should be made to agree on a unique worldwide standard for DAB and 2. to urge
8、 administrations to give consideration to the benefits for the consumer of common source and channel coding and implementation of Digital Sound Broadcasting on a worldwide basis at 1.5 GHz”; 2 Rec. ITU-R BS.1547 j) that the World Administrative Radio Conference (Malaga-Torremolinos, 1992) (WARC-92)
9、allocated the band 1 452-1 492 MHz to the BSS (sound) and complementary terrestrial broadcasting service for the provision of DSB. Also, additional footnote allocations were included for specific countries in the band 2 310-2 360 MHz and in the band 2 535-2 655 MHz in Radio Regulations (RR) Nos. 5.3
10、93 and 5.418, noting a) that a summary of the digital systems that allow hybrid operation is presented in Annex 1; b) that condensed system descriptions for Digital System DHand E are given in Annexes 2 and 3; c) that complete systems descriptions of Digital System DHand E are contained in the DSB H
11、andbook, recommends 1 that administrations that wish to implement hybrid satellite/terrestrial DSB services meeting most or all of the requirements as stated in Recommendation ITU-R BS.774 should consider either of the two Digital Systems, DHor E, using Table 1 to evaluate their respective merits. (
12、see Note 1). This should be done in conjunction with the consideration of Recommendation ITU-R BO.1130 for the satellite portion in view of the selection of an overall hybrid BSS (sound) system. NOTE 1 Technology in this area is developing rapidly. Accordingly, if additional systems meeting the requ
13、irements given in Recommendation ITU-R BS.774 are developed, they may also be recommended for use when brought to the attention of the ITU-R. Administrations engaged in the development of DSB systems should make efforts to bring about, as much as possible, harmonization with other systems already de
14、veloped or currently under development. TABLE 1 Performance of Digital Systems DHand E evaluated on the basis of the recommended technical and operating characteristics listed in Recommendation ITU-R BS.774 Characteristics from Recommendation ITU-R BS.774(condensed wording) Digital System DHDigital
15、System E 1. Range of audio quality and types of reception Range is from 16 kbit/s to 128 kbit/s per audio channel in increments of 16 kbit/s. Each 16 kbit/s increment can be split into two 8 kbit/s services. MPEG-2 and MPEG-2.5 Layer III audio coding are used. The system is intended for vehicular, p
16、ortable and fixed reception Range is from 16 kbit/s to 320 kbit/s per audio channel in any increment size. MPEG-2 AAC audio coding is used. The system is intended for vehicular, portable and fixed reception Rec. ITU-R BS.1547 3 TABLE 1 (continued ) Characteristics from Recommendation ITU-R BS.774 (c
17、ondensed wording) Digital System DHDigital System E 2. Spectrum efficiency better than FM FM stereo quality achievable in less than 200 kHz bandwidth; co-channel and adjacent channel protection requirements much less than that for FM. (QPSK modulation with concatenated block and convolution error co
18、rrecting coding) FM stereo quality achievable in less than 200 kHz bandwidth; co-channel and adjacent channel protection requirements much less than that for FM. (CDM based on QPSK modulation with concatenated block and convolutional error correcting coding) 3. Performance in multipath and shadowing
19、 environments The system is a hybrid satellite/terrestrial system designed for diversity reception of a TDM signal via satellite complemented by a terrestrially retransmitted MCM signal. MCM is especially designed for multipath operation. It works by power summing the echoes falling within a given t
20、ime interval System is especially designed for multipath environment. It works on the basis of receiving power summation of multipath using a RAKE receiver. This feature allows the use of on-channel repeaters to cover shadowed areas. Also, more than 1 s blackout will be recovered using segmented con
21、volutional bit wise interleaver 4. Common receiver signal processing for satellite and terrestrial broadcasting Receivers are being developed for TDM-MCM reception in urban environments, including mobile applications. A TDM-MCM signal is radiated from terrestrial transmitters that repeat the satelli
22、te TDM. Circular polarization is used for satellite reception, vertical for terrestrial. External antennas are used for mobile This system is based on the simultaneous reception from both satellite and complementary on-channel repeaters. Allows the use of the same receiver, from the RF front end to
23、the audio and data output Adoption of MPEG-2 systems achieves maximum interoperability among the same kind of digital broadcasting receivers, e.g. ISDB-S, ISDB-T, and DVB-T, DVB-S through using future interconnection mechanism, i.e. IEEE1394 4 Rec. ITU-R BS.1547 TABLE 1 (continued ) Characteristics
24、from Recommendation ITU-R BS.774 (condensed wording) Digital System DHDigital System E 5. Reconfiguration and quality vs. number of programme trade-offs A flexible 16 kbit/s building block multiplex is employed. Up to 8 blocks can be assigned to each broadcast channel in order to trade off programme
25、 audio quality against number of services. Assignment to services is dynamically adjustable. FM-quality audio achieved at 64 kbit/s. All blocks are error protected. Data service transports streamed data and data packets Multiplexing of payload data is based on MPEG-2 systems. Audio data rate can be
26、selected in any step in order to trade off programme audio quality against the number of services. Higher-data rate service is possible using more than one CDM channel per programme audio stream 6. Extent of coverage vs. number of programme trade-offs The system is optimized for diversity reception
27、from satellite(s) and terrestrial repeaters. The trade off between extent of coverage and system throughput is fixed Data rate of single CDM channel can be selected from 236 kbit/s to 413 kbit/s through using punctured convolutional coding. (Code rate can be selected from 1/2, 2/3, 3/4, 5/6 or 7/8)
28、7. Common receiver for different means of programme delivery: Mixed/hybrid Terrestrial augmentations Cable distribution Allows hybrid use of satellite and complementary terrestrial transmissions in the bands allocated for BSS (sound) by WARC-92. A common receiver will receive the satellite TDM and t
29、he terrestrial MCM emissions that reinforce the satellite emissions. Allows local, subnational and national services with TDM-MCM modulation in terrestrial SFNs and TDM-QPSK in satellite line-of-sight via a common receiver. Signal can be carried transparently by cable Allows the use of the same band
30、 as terrestrial sound broadcasting (mixed) as well as the use of terrestrial on-channel repeaters to reinforce the satellite coverage (hybrid) resulting in all these channels being received transparently by a common receiver. Allows local, subnational and national terrestrial services with the same
31、modulation with a single transmitter or multiple transmitters operating in a SFN to take advantage of a common receiver. Signal can be carried transparently by cable Rec. ITU-R BS.1547 5 TABLE 1 (end) Characteristics from Recommendation ITU-R BS.774 (condensed wording) Digital System DHDigital Syste
32、m E 8. PAD capability PAD comprising text (dynamic labels) and graphics with conditional access control can be delivered PAD multiplexing is based on MPEG-2 systems. Data services are available using any CDM channel and a part of CDM channel 9. Flexible assignment of services The multiplex can be dy
33、namically re-configured in a fashion transparent to the user The multiplex can be dynamically re-configured in a fashion transparent to the user 10. Compatibility of multiplex structure with OSI Multiplex structure is compatible with the OSI layered model The system multiplex structure is fully comp
34、liant with MPEG-2 systems architecture 11. Value-added data capability Capacity in increments of 8 kbit/s up to the full 1.536 Mbit/s capacity of the TDM can be assigned to independent data for the delivery of business data, paging, still pictures graphics etc. under conditional access control if de
35、sired. A data connector is provided on the receivers for interfacing to information networks Capacity at any rate up to the full payload capacity (depends on the number of CDM channels multiplexed) can be assigned to independent data for the delivery of business data, paging, still pictures graphics
36、 etc. under conditional access control if desired 12. Receiver low-cost manufacturing The satellite and MCM-TDM signal reception and digital processing will be embedded in microchips suitable for mass production The system was specifically optimized to enable an initial low complexity vehicular rece
37、iver deployment. Standardization group has been established to achieve low cost receivers based on large scale integration mass production techniques AAC: advanced audio coding CDM: code division multiplex DVB: digital video broadcasting FM: frequency modulation IEEE: Institute of Electrical and Ele
38、ctronics Engineers ISDB: integrated services digital broadcasting MCM multi-carrier modulation MPEG: Moving Pictures Experts Group OSI: open system interconnection PAD: programme associated data QPSK: quadrature phase shift keying RF: radio frequency SFN: single frequency network TDM: time division
39、multiplex 6 Rec. ITU-R BS.1547 ANNEX 1 Summaries of digital systems 1 Summary of Digital System DHDigital System DH,also known as the hybrid satellite/terrestrial WorldSpace system, is designed to provide satellite digital audio and data broadcasting for vehicular, fixed and portable reception by in
40、expensive common receivers. The satellite delivery component of Digital System DHis based on the same TDM broadcast channel transport used in Digital System DSbut with several significant enhancements designed to improve line-of-sight reception in areas partially shadowed by trees. These enhancement
41、s include fast QPSK phase ambiguity recovery, early/late time diversity and maximum likelihood combination of early/late time diversity signals. It extends the system structure of Digital System DSby adding the terrestrial delivery system component based on MCM. MCM is a multipath-resistant orthogon
42、al frequency division multiplex (OFDM) technique that has gained wide acceptance for pervasive mobile reception from terrestrial emitters. The MCM extension improves upon the techniques which are common in systems such as Eureka 147, which is one standard utilized for terrestrial microwave digital a
43、udio broadcast services. MCM utilizes multiple frequencies to avoid frequency selective fades to avoid deleterious effects of delay spread. 2 Summary of Digital System E Digital System E, also known as the Association of Radio Industries and Businesses (ARIB) system, is designed to provide satellite
44、 and complementary terrestrial on-channel repeater (hybrid) services for high quality audio and multimedia data for vehicular, portable and fixed reception. It has been designed to optimize performance for both satellite and terrestrial on-channel repeater service delivery in the 2 630-2 655 MHz ban
45、d. This is achieved through the use of CDM based on QPSK modulation with concatenated block and convolutional error correcting coding. The Digital System E receiver uses state-of-the-art microwave and digital large-scale integrated circuit technology with the primary objective of achieving low-cost
46、production and high-quality performance. ANNEX 2 Digital System DH1 Introduction Digital System DH, also known as the hybrid satellite/terrestrial WorldSpace system, is designed to provide satellite digital audio and data broadcasting for vehicular, fixed and portable reception by inexpensive common
47、 receivers. It extends the system structure of Digital System DS, described in Recommendation ITU-R BO.1130. Digital System DSwas designed to optimize performance Rec. ITU-R BS.1547 7 for satellite delivery using coherent QPSK modulation with block and convolutional coding, and non-linear amplificat
48、ion at travelling wave tube amplifier (TWTA) saturation. It is now operating over Africa using the WorldSpace AfriStar satellite at 21 East and over Asia using the AsiaStar satellite at 105 East. The system provides for a flexible TDM of digitized audio and data sources to be modulated onto a downli
49、nk TDM carrier, and uses a hierarchical multiplex structure of three layers (physical, service and transport) that conforms to the OSI Model as recommended in Recommendation ITU-R BT.807. Since the launch of AfriStar in October 1998 Digital System DSsystem has been delivering a satellite direct digital broadcast service over Africa. With the launch of AsiaStar in March 2000 the same service has started over Asia. Both satellites are delivering direct digital broadcast signal reception with very high margins of 4 to 13 dB within their outer beam coverage contour areas of 2
