Leo Satellite Communications System To Switch The Channel Allocation Strategy

The satellite mobile communication can realize the radio communication between the mobile terminals by using the satellite repeaters which acts as relay. Among the satellite mobile communication systems, the LEO-MSS (Low Earth Orbit Mobile Satellite Systems) possess the wide development space due to their global seamless coverage, much shorter transmission delays, less power requirement for the user terminals and strong ability in anti-ruin. Moreover, they will play an important role in the future Personal Communication Systems (PCS).Because of the relative movement between the LEO satellites and the terrestrial user terminals, the very high handover rate during a call's lifetime, including inter-spotbeam handover, inter-satellite handover and handover between satellite communication systems and terrestrial ones, will occur. In the process of the handover, in order to increase the resource utilization efficiency, the problem on how to fulfill the optimal allocation of the channels should be solved.In this thesis, the handover and channel assignment schemes in LEO-MSS are introduced and discussed deeply. On the basis of the integrated consideration on handover, channel allocation and resource reservation, the appropriate handover and allocation techniques are proposed so as to reduce the call blocking probability and handover failure probability. Thus, the proposed schemes can improve the channel utilization efficiency and the system performance. This paper is divided into 3 topics and provides a detailed discussion on these topics in chapter 2, 3 and4 respectively.In Chapter 2, the channel assignment techniques in the inter-spotbeam of the LEO-MSS are studied. A new channel allocation scheme ICA (namely, Initial Channel Assignment) is introduced according to the inherent characteristic of LEO-MSS. The proposed ICA scheme can handle non-uniform traffic distribution over the coverage and guarantee the fairness for all cells and the priority for the cells where traffic conditions are heavy.In Chapter 3, the DCA (Dynamic Channel Assignment) and DCR (Dynamic...