Satellite selection scheme for reducing handover attempts in LEO satellitecommunication systems

Low earth orbit (LEO) satellite communication systems perform frequent inte rsatellite handovers for both foxed and mobile users. This paper proposes a satellite selection scheme for new/handover call requests when two or more satellites can be seen simultaneously. Each satellite in this scheme has a non-uniform transmitter antenna gain according to its relative position in side the coverage area. The antenna gain is proportional to the residual di stance in the satellite's direction of movement and it compensates for the difference in path losses between satellite links. The residual distance di stribution of the selected satellite and the mean number of intersatellite handovers during a call connection are calculated and compared with the res ults based on conventional methods. The proposed scheme can reduce the inte rsatellite handover call attempt rate without increasing system load and te rminal complexity. Furthermore, this scheme can be extended to reduce both intersatellite and interbeam handover call attempt rates in a multiple spot beam environment. Especially, the average number of intersatellite and int erbeam handovers during a call can be significantly reduced by using a hybr id algorithm with the proposed non-uniform power transmission scheme. (C) 1 998 John Wiley & Sons, Ltd.