Research On The Key Technologies For LEO Small Satellite Communication And Positioning

There are intense attentions having been payed on the LEO small satellite mobile communication system in the research filed of satellite communication technologies in recent years. With the understanding view that the LEO satellite system is the important means to achieve the goal of global and personal communication, the small satellite has been regarded as one of the important ways to make breakthrough for the bottlenecks in the field. According to the characteristic and the development status of LEO satellite mobile communication system, several optimal designing technologies on the background of small satellite in the field are researched in this dissertation. They are the media access control protocol, routing and rerouting technology in the LEO satellite constellation networks, the estimation of power gain in the channel of LEO mobile communication, and the LEO satellite positioning technology.Chapter 1 introduces the concept and development trends of modern small satellite system, then classifies the types of satellite mobile communication systems and their current development status, and then points out the main difficulty encountered in the development of satellite mobile communication. The key technologies should be developed in that systems which will apply the small satellite technology are presented, and the contents of this dissertation are also outlined.Chapter 2 studies the MAC protocol in the LEO satellite communication system. After the analysis of the MAC protocol and their performance influencing factors, a packet reservation multiple access protocol (PRMA) with access control mechanism (PRMA-AC) and the corresponding mathematical analysis model is proposed. Main task of this protocol is to resolve the problem encountered in the real time communication environment with long time delay and large amount of user terminals. The research of the PRMA-AC protocol is based on the analysis of traditional satellite PRMA protocol, which points out that the packet drop rate will be high in the environment of satellite communication with large amount of user terminals. After that analysis the scheme of the protocol is set up through the dectuction with MARKOV state transition model, and the protocol's performance of throughput rate, packet drop rate are deduced, and the result of the analysis is validated by the computer simulation.