Research On The Medium Access Control Protocol Of Satellite Optical CDMA Communication Systems

Traditional satellite communication system employing microwave technology has some inherent defects,such as limited frequency bandwidth,relatively small communication capacity and large divergence.While satellite communication system using optical code division multiple access(OCDMA)technology has some advantages,for example,large transmission capacity,anti-interference,good privacy and so on.However,the focus of main present research is on the physical link layer techniques,including characteristics of inter-satellite communication link,modulation demodulation,and acquistion,tracking and pointing(ATP).The research on the data link layer and higher layers is relatively not much.The medium access control(MAC)protocol greatly influences the bandwidth utilization,resource allocation,cost of equipment and complexity of the system in the satellite OCDMA system.Therefore,the research on the MAC protocols used in OCDMA communication system is significant.The thesis first summarizes the exiting MAC protocols,and a detailed introduction is given to the principles and features of the fixed multiple access protocol,random multiple access protocol,reservation multiple access protocol and hybrid multiple access protocol.Secondly,it describes the advantages,principles and key techniques of the satellite OCDMA.A mathematical simulation model,including transmitter module,channel module and receiver module,is built to analyze the bit error ratio(BER).Through a detailed analysis on the principle of CDMA-PRMA protocol,we apply it to the satellite optical CDMA network,and design a satellite optical CDMA Packet Reservation Multiple Access Protocol(S-OCDMA-PRMA).We analyze the packet loss probability of the S-OCDMA-PRMA protocol when transmitting voice packets,and study such a performance with the simulation and by programming.The simulation results show that the performance of S-OCDMA-PRMA protocol is better than that of the traditional CDMA-PRMA protocol,i.e.,the proposed S-OCDMA-PRMA can permit more users simultaneously communicate compared to the traditional CDMA-PRMA at the same packet loss probability.Finally,the autor concludes the thesis and presents the future research work.