Channel Reservation In Mobile Satellite Communications Network Access Control Strategy

As an important part of personal communications, Low Earth Orbit (LEO) satellite communications will make an important role in the future Personal Communication Systems (PCS) for their global seamless coverage, less propagation delay, less power requirement in the user terminal and the satellites.Since LEO's high-speed movement comparatively to the earth, a call may be subjected to high-rate handovers. In the process of 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 dissertation, the handover and channel assignment schemes in LEO-MSS's are introduced and discussed. On the basis of the integrated consideration on handover, channel allocation and resource reservation, the appropriate handover and channel 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 in chapter 2, 3, 4 respectively.Chapter 1 gives brief introduction of satellite communication system and the main work of this dissertation.Chapter 2 studies the channel assignment techniques in the inter-spotbeam of the LEO-MSS's. Considering the feature of LEO satellite systems, a probability-based channel reservation scheme is introduced for LEO satellite systems based on the low handover failure probability. The scheme calculates the call termination probability of the prioritized new call in source cell in advance. According to the probability, it decides to reserve channel in the first transit cell whether or not. This scheme guarantees the low handover failure probability, at the same time, the new call blocking probability has been reduced significantly.Chapter 3 proposes an adaptive channel reservation scheme for integrated voice and data LEO satellite mobile communication systems. Based on the new call block probability and the handover failure probability, the scheme reserves channels dynamically. Moreover, it gives handover voice calls a higher priority by permitting them to preempt handover data calls'channels in preemptive channel. The results by analysis and simulation in grade of service and channel utilization prove the better performance of this scheme.Chapter 4 introduces a two-layered satellite network system which combines the advantage of media earth orbit system and low earth orbit system. Based on this system, the access schemes of this network are researched and the performance of these algorithms are analyzed and simulated. The parameters such as original call block probability, handover failure probability are compared and some valuable results have been obtained.The dissertation is summarized in the last chapter. Finally, the future research work is pointed out.