1、- STD.ITU-R RECMN M-3312-ENGL 3997 4855232 0532979 406 Rec. ITU-R M.1312 289 RECOMMENDATION ITU-R M. 13 12* A LONG-TERM SOLUTION FOR IMPROVED EFFICIENCY IN THE USE OF THE BAND 156-174 MHz BY STATIONS IN THE MARITIME MOBILE SERVICE (Question ITU-R 96/8) (1997) Summary The long-term requirement within
2、 the international maritime mobile community is for an advanced spectrally efficient digital system to provide improved efficiency in the use of the band 156-174 MHz. This Recommendation provides administrations with an example of such a technology which is being implemented for land mobile communic
3、ations in certain areas. The ITU Radiocommunication Assembly, considering a) that Recommendation No. 3 18 of the World Administrative Radio Conference for the mobile services (Geneva, 1987) (WARC Mob-87) seeks the most appropriate means to improve efficiency in the use of the Radio Regulations (RR)
4、Appendix 18 (S18) VHF frequency spectrum for maritime mobile communications; b) c) use of digital and narrow-band technology; d) mobile sector; e) the latest digital or narrow-band transmission techniques; f, that changes to RR Appendix 18 (S18) were considered by World Radiocommunication Conference
5、 (Geneva, 1997) (WRC-97); g) that a common international system is essential for maritime communications to ensure the safety of life at sea; h) that the introduction of new technology to the maritime mobile service shall not disrupt the distress and safety communications in the VHF band, including
6、those established by the International Convention of Safety of Life at Sea, (SOLAS) 1974 as amended; j) that any new equipment need to be compatible or be able to coexist with existing equipment conforming to relevant parts of Recommendation ITU-R M.489 (former RR Appendix 19) already in widespread
7、use; k) that the introduction of new technology should not interrupt the continuous availability of RR Appendix 18 (S 18) maritime mobile distress and safety communications in the VHF bands for all users; 1) involving a long period of transition, that the ITU-R is conducting studies on the improved
8、efficiency in the use of this band; that the ITU-R is conducting studies on the improved efficiency in land mobile communications through the that the maritime mobile communications sector does not enjoy the economies of scale experienced by the land that the studies to date indicate the greatest lo
9、ng-term benefits in spectrum efficiency will be gained by using that the introduction of new technology or replanning of frequency bands will be a significant exercise recommends that administrations should, as far as possible, look to the implementation of the latest digital or narrow-band 1 techni
10、ques to meet future operational requirements and achieve the efficient use of the band 156-174 MHz; * This Recommendation should be brought to the attention of International Maritime Organization (IMO). COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information H
11、andling Services STDmITU-R RECMN M-II3LZ-ENGL 1997 m 4855232 0532980 328 m 290 Rec. ITU-R M.1312 2 that the international maritime community should look to developments within the land mobile communications sector in future digital and narrow-band communications in order to benefit from the economie
12、s of scale within that sector. (A relevant ITU-R Recommendation for digital land mobile technologies is still under development.); 3 that the international maritime community should consider amongst others (see comment), the use of an advanced spectrum efficient technology, an example of which is de
13、scribed in Annex 1; this technology has been adopted for land mobile communications in certain areas to provide improved spectrum efficiency and system capabilities. (Comment - For land mobile communications different technologies are available, utilising other types of modulation and other access m
14、ethods than the one described in Annex 1; these should also be analyzed to see whether they serve the needs of the maritime community, taking into account the economic aspect.) ANNEX 1 Example of an advanced spectrally efficient digital system The following characteristics could be considered by the
15、 international community for implementation as an advanced spectrum efficient technology within the maritime mobile service in the band 156-174 MHz. Designation of emission: - Traffic channels: - Control channels: Access method: Number of traffic channels per RF carrier: Data transmission rate: Modu
16、lation: RF carrier spacing: 25 kHz Maximum base station effective radiated power (e.r.p.): Mobile stations transmit power: Area coverage technique: - Cellular channel reuse 25 W peak 25 W average 10 W to 0.25 W - Quasi-synchronous (simulcast) - Time sharing transmission - Diversity receivers 25KOD7
17、W125KWDW 25KOD7W/25KWDW TDMA (Time Division Multiple Access) 36 kbiils DQPSK (n/4 Differentially Coherent Quaternary Phase Shift Keying) 4-8 Traffic channel structure: - Bit rate: - Error protection: - Coding algorithm: Control channel structure: - Common control channel: - Associated control channe
18、l: - Broadcast control channel: Delay spread spectrum equalization capability: - Class A single tx operation: - Class B single tx operation: - Class Q quasi-synchronous operation: Channel coding: 4.567 kbit/s 2.633 ACELP (Algebraic Codebook Excited Linear Prediction) 2 channel types 3 channel types 2 channel types No equalization 55.5 ps 111.1 ps Convolutional codes with interleaving plus error detection COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services
