Inter-satellite links for personal communications low Earth orbit satellite systems

The introduction of inter-satellite links (ISL) in low Earth inclined orbit satellite systems for mobile communications to hand-held terminals has been studied in the hypothesis of a service beginning just before the year 2000. Some of the major results of the study are presented. The analyses performed led to the conclusion that ISLs may be interesting for improvement of the path diversity performance and for reduction of the number of hub stations required on Earth. Their implementation can be achieved with advanced on-board technology (Ka-band RF equipment and digital processing) which is under study and development. It therefore appears realistic in view of the contemplated time-frame. The impact of ISLs on the system operational complexity has also been analyzed and it appears as the most critical issue: increased traffic and resource management procedures, increased signaling overheads, requirement for commanding the satellite switches, etc. Finally, the conclusion is that ISLs could be envisaged for the first generation of LEO systems, but more system and economical studies would be necessary to make a definite assessment