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M u l t i b e a m s a t e l l i t e c o m m u n i c a t i o n s systems are expected to play an important role in constructing economical and highly reliable communications networks in combination with terrestrial networks. They will provide a t t r a c t i v e n e w c o m m u n i c a t i o n s s e r v i c e s promptly and widely.NTT is making intensive efforts in the research and development of multibeam satellite communications systems and is planning to carry out flight vcrification of the system using Engineering Test Satellite-VI (ETS-VI) which will be launched in 1992. This paper describes the configuration and characteristics of the experimental systems for fixed and mobile satellite communications.

In cellular mobile communication systems, radio channels are repeatedly used in order to efficiently use assigned frequency bands. The computation time for the optimization of channel assignment increases with the increase of cell number. This paper presents a group channel assignment method for the optimization and its simulation results. This method utilizes the genetic algorithm (GA). Prior to the optimization calculation, whole channel cells are divided into subgroups and then, each subgroup is optimized. Using this result, the whole cells are further optimized. This process enables an efficient calculation to optimize the channel assignment. The results of simulation shows that the proposed method gives a shorter computation time compared with the method called as the individual assignment.

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