| WP 8D is responsible for studies related to all mobile-satellite services (MSS) and the radiodetermination-satellite service. The objectives of WP 8D activities are to develop and maintain ITU-R Recommendations and the MSS Handbook in the areas of geostationary and non-geostationary orbit mobile satellite systems and radionavigation-satellite service systems. Recent development of MSS systems is so rapid that studies have been intensively conducted on technical and operational characteristics of MSS and frequency sharing with other services. Studies on the radionavigation-satellite service are equally active to support operation of RNSS systems and expansion of frequency allocations for further development. The ITU-R M Series of Recommendations provides the unique and indispensable basis in the relevant technical areas for administrations, international and regional organizations, satellite system operators as well as industry. The introduction of new technologies enhances efficiency and areas of application of MSS systems. Significant progress in MSS includes the following aspects: - Application areas have been enhanced from maritime to aeronautical and land-mobile communications.
- New MSS systems have been developed by non-geostationary orbit satellites as well as by geostationary orbit satellites.
- Handheld terminals are already in use for new MSS systems.
- In addition to voice transmission, various data applications are provided such as store-and-forward transmission and packet-data transmission.
Technical and operational studies have resulted in a number of ITU-R M Series Recommendations to support these new features of MSS systems. Technical characteristics of mobile terminals have been one of the active study areas because MSS by its nature has an extremely wide or world-wide coverage, where better circulation of terminals increases the benefits foreseen in Global Mobile Personal Communications by Satellite (GMPCS). MSS also plays an important role in safety applications that include Global Maritime Distress and Safety Service (GMDSS) and Satellite Emergency Position Indicating Radio Beacon Station (Satellite EPIRBS). Aeronautical MSS is also applied for route services (AMS(R)S) to support communications relating to safety and regularity of flights, primarily along national and international civil air routes.WP 8D has also been given responsibility for studies on the satellite component of IMT-2000, in close coordination with WP 8F which is responsible for overall aspects of IMT-2000 and systems beyond and the terrestrial component. WP 8D is developing an MSS Handbook which is intended to provide basic information about MSS for non-expert readers and and to serve as a general reference for MSS experts. The Handbook covers subjects specific to MSS, such as a brief history of MSS development, various MSS services, types of satellite orbit, allocated spectrum, technical features in system design and practical example systems.
A large amount of effort has been concentrated on frequency sharing studies with other services such as MS, FS, Radiolocation, Space Research, Meteorological Aids services, etc. Spectrum allocated to MSS has been expanded in line with the rapid development of MSS. To ensure efficient and reliable use of the spectrum, frequency sharing methodologies have been intensively studied together with sharing criteria and coordination processes. It should also be noted that adjacent channel interference has become increasingly important, in addition to co-channel interference. Out-of-band unwanted emissions are now a major area of study for terminal characteristics as well as in frequency sharing studies. A number of ITU-R M Series Recommendations have been developed as result of these frequency sharing studies. |
