【作者】 卓永宁；

【导师】 吴诗其；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2006， 博士

【摘要】 近年来低轨小卫星移动通信技术引起人们广泛关注。低轨卫星移动通信技术是实现通信全球化、个人化和宽带化的重要手段，利用小卫星是突破这一技术面临的诸多瓶颈的重要手段之一。本文根据低轨卫星移动通信技术的特点和发展趋势，对在小卫星条件下低轨移动通信系统的优化设计技术，包括媒体接入控制协议、低轨卫星星座网络的路由和重路由技术、低轨卫星移动通信的功率增益估计和利用低轨卫星进行定位等几个方面进行了较为深入的研究。 第一章为绪论，首先介绍了现代小卫星系统的概念，列举了小卫星系统的未来发展趋势，然后介绍了卫星移动通信系统的几种类型和发展现状，指明了卫星移动通信发展中面临的主要问题，说明了小卫星系统用于卫星移动通信所要解决的关键技术问题，并介绍了本论文取得的成果和内容安排。 第二章研究了低轨卫星通信中的媒质控制层(MAC)协议，首先对卫星通信中的MAC协议和影响MAC协议性能的因素进行了说明，分析了传统预约多址协议PRMA在卫星应用环境下的性能，在此基础上提出了一种具有拥塞控制功能的卫星预约多址协议PRMA—AC并建立了协议的数学分析模型。该协议主要解决在大时延、大用户数量情况下支持实时通信的问题，协议在卫星PRMA—HS协议基础上引入接入控制机制。本章通过该协议的MARKOV状态转移稳态方程，建立了协议的理论分析模型，深入分析了该协议的吞吐率、丢包率等性能指标，通过仿真验证了理论公式的正确性，并与现有其他卫星预约多址PRMA协议进行了对比，说明了该协议的比较优势。本章还对另一种ALOHA协议在小卫星应用背景下的性能改进方案进行了研究，提出了可自适应调整终端发送概率，并利用CDMA技术增强系统负荷能力的自适应时隙ALOHA／CDMA协议，该协议用于支持小卫星系统在热点地区大量终端情况下的猝发式数据通信。仿真分析表明该协议在大容量情况下，系统鲁棒性较强，能够满足工程需要。 第三章研究了含星际链路的低轨卫星网络的路由和重路由算法，提出了基于地理网格映射的路由策略，以及基于最短K路由算法的时延抖动抑制的重路由优化算法。本章首先对目前在卫星网络研究中提出的路由策略和算法进行了介绍，然后针对时延及时延抖动性能要求较高的实时性业务，提出了基于地理网格区域映射的卫星路由策略。基于地理网格区域映射的路由策略将用户终端归属于地面上按地理位置划分好的网格区域中，类似于地面移动通信中的服务区概念，简化更多还原

【Abstract】 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.更多还原