Rec. Itu-r m. 1184-1

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Rec. ITU-R M.1184-1



(Question ITU-R 201/8)


Rec. ITU-R M.1184-1
The ITU Radiocommunication Assembly,

a) that Resolution 214 (Rev.WRC-97) resolves that further studies are urgently required on operational and technical means to facilitate sharing between the non-GSO MSS and other radiocommunication services having allocations and operating below 1 GHz;

b) that, while some MSS system parameters are still under development, a summary of representative technical characteristics of MSS systems is useful for conducting sharing studies and for development of appropriate sharing criteria by the ITU-R;

c) that MSS system designs will evolve and new MSS systems may be proposed and therefore representative characteristics should be maintained as an on-going activity,


a) that the necessary frequency sharing studies require the involvement of several Radiocommunication Study Groups;

b) that the technical parameters in this Recommendation are referenced and used in several other ITU-R Recommendations;

c) that MSS networks and the associated lists of the technical parameters in this Recommendation have been chosen specifically for use in modelling frequency sharing and interference,


1 that the representative technical characteristics for non-GSO MSS systems, as given in Annexes 1 and 2, be used by the ITU-R in conducting sharing studies and in the development of Recommendations on sharing criteria for non-GSO MSS systems;

2 that the representative technical characteristics for geostationary MSS systems given in Annexes 1 and 2 be used for conducting sharing studies and in the development of ITU-R Recommendations on sharing criteria for geostationary MSS systems;

3 that the characteristics given in Annexes 1 and 2 be updated periodically to reflect changes in the MSS example system designs and to incorporate new MSS system examples as they are proposed and as their designs mature.


Characteristics of representative 1 3 GHz MSS networks

1 Satellite orbits

Currently, the GSO is being used for the MSS. Some proposed mobile-satellite systems plan to use non-GSO orbits. Suitable orbits are determined by coverage requirements, service considerations and frequency sharing, as well as other considerations.

2 Global and regional/national GSO systems

Current Inmarsat and Russian Volna satellites utilize Earth-coverage antennas to provide near-global coverage from the GSO. The Russian systems are similar to those of Inmarsat systems, the characteristics of which are presented in Table 2. Several administrations are implementing regional/national GSO mobile-satellite systems to provide aeronautical, land and maritime services at 1.6/1.5 GHz. In addition to the above systems at 1.6/1.5 GHz, Japan is planning to put into operation a GSO mobile-satellite system in the 2.6/2.5 GHz bands.

The future generation of Inmarsat and Russian satellites and the planned regional and national systems will use spot beam to provide greater spectrum efficiency and conserve transmitted power of the satellite and mobile earth station.

2.1 Maritime mobile-satellite service

The Inmarsat-B system provides a power and bandwidth efficient replacement for the original INMARSAT A and provides voice, facsimile, data and telex services. In parallel with Inmarsat B, Inmarsat M uses lower symbol transmission rates for voice, data and facsimile requirements for smaller ships. The Inmarsat C system provides store and forward data and telex using small, low cost equipment.

2.2 Aeronautical mobile-satellite service

The International Civil Aviation Organization (ICAO) Standards and Recommended Practices (SARPs) for aeronautical mobile satellite (R) service (AMS(R)S), airborne equipment have been published in Annex 10 to the Convention on International Civil Aviation. The SARPs include a requirement for priority and pre-emption for safety communications over all other communications. All systems providing AMS(R)S services to the international civil aviation community have to conform with the applicable ICAO SARPs.

In summary, the aeronautical satellite communication systems will have to take into account the priority needs for safe operation of aircraft and the avionics will have to satisfy the severe requirements of aircraft environments.

2.3 Land mobile-satellite service

The land mobile-satellite service (LMSS) has proven to be an effective means for providing dependable communications in remote and sparsely populated areas, either as extensions of terrestrial VHF and UHF networks or as replacements for HF networks. Worldwide roaming capability is a mandatory function of International Mobile Telecommunications-2000 (IMT 2000) and the satellite component defined in Recommendations ITU-R M.687 and ITU-R M.818 is one of the important components that encourage the IMT 2000 capability. The interworking of the mobile satellite system with the terrestrial system can encourage user convenience within not only IMT 2000 but also general LMSS.

2.4 Distress and safety service

Technical and operating characteristics of the Inmarsat 1.6 GHz satellite EPIRB system are described in Recommendation ITU-R M.632.

Tables 1-3 present representative technical characteristics of service links for selected MSS networks that utilize space stations in GSOs.

3 Non-GSO MSS system characteristics

Proposed personal communication systems using non-GSO satellites, including satellites using low, medium and intermediate orbits, are expected to provide voice, data communications and positioning on a worldwide basis using mobile terminals or hand-held portable terminals using omnidirectional antennas.

Operation in a band contiguous with future land mobile communication systems would permit interoperability between non-GSO MSS and land mobile systems.

Table 4 presents representative technical characteristics of service links for selected MSS networks that utilize space stations in non GSOs.

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