| The objective of this research work is to define and analyze a new multiple access technique suitable for a class of centralized multiple satellite networks with on-board processing on the central node. This work also provides analytical solutions to the problems arising in the development of the proposed multiple access technique. This multiple satellite network provides real-time global intersatellite and satellite to ground communications among a large number of low orbit user satellites and small earth terminals and supports users with different characteristics (size, data rate, and mobility). The major advantages of the proposed multiple access technique are minimum need for network synchronization, resistance to jamming, low equipment complexity, low mutual interference, excellent delay-throughput performance, ease for network expansion, simple architecture for the user satellites, and low overall network cost.; This dissertation starts with describing the need for multiple satellite networking, the possible architectural designs for multiple satellite networking, the architecture of the proposed class of multiple satellite system, and the objective of the research work. The applicability of the existing multiple access techniques to this class of centralized multiple satellite systems with highly dynamic users is critically evaluated, and the new Code Division Multiple Access/Aloha/Beam Forming Network (CDMA/Aloha/BFN) multiple access technique is proposed. The type and amount of the required communication and processing hardware for the proposed multiple access technique and the architecture of the central satellite stations are also presented. The proposed multiple access technique is a combination of Code Division Multiple Access (CDMA), Random Multiple Access (RMA), or Aloha, and a set of electronic Beam Forming Networks (BFN). The CDMA/Aloha/BFN maintains the advantages of the CDMA (no collision, signal separation, and anti-jamming) and RMA (no need for network synchronization and simplicity of operation) techniques and avoids their disadvantages (inefficient use of bandwidth and mutual interference for CDMA; high probability of collision and poor delay-throughput performance for RMA) by using some processing on board the central satellite stations.; After introducing the architecture of the central satellite station, the structure of its baseband processor is defined. Analytical models are developed and used to optimize the system delay-throughput performance. Then the theory of operation of the proposed CDMA/Aloha/BFN multiple access technique is described and its delay-throughput performance and message error rate performance are analyzed. Finally, a method of very stable and quick burst synchronization is developed for the satellite networks using the CDMA/Aloha/BFN multiple access method. In this connection, analytical expressions for calculating the time to synchronize are developed. |
