【作者】 顾燕；

【导师】 张源；

【作者基本信息】 东南大学 ， 通信与信息系统， 2022， 硕士

【摘要】 随着互联网的发展,用户对通信服务提出了跨区域、多媒体、实时互动、万物互联等等多种要求,通信行业致力于发展高速率、大容量通信,卫星移动通信以其传输容量大、传输质量高的特点进入到市场中。高通量的多波束卫星通信系统逐渐取代传统的卫星通信,成为了当前卫星通信的发展趋势。考虑到多波束卫星通信系统在结构上与地面MIMO通信系统相似,因此引入全频率复用技术提高频带利用率,扩大通信容量并缓解频带资源紧张的困局。首先分析了卫星与地面移动终端之间的无线传输信道。针对卫星移动通信传输信道存在的多径效应、阴影效应、多普勒频移、天气影响和电离层闪烁等对传输性能造成的影响,分析这些影响因素产生的衰落特征。考虑到卫星移动通信的传输过程中,这些影响因素导致卫星移动信道具有不确定性,但在一定时间内信道具有统计特性,因此我们给出了Loo模型、Corazza模型、Lutz模型以及莱斯阴影模型这四种不同的卫星统计信道模型。另外,阐明了信道建模时考虑的衰落因素,在经典卫星信道模型的基础上推导得到所用的信道模型。搭建了多波束卫星MIMO传输的系统模型,根据不同的影响因素,在仅考虑相位噪声和考虑相位噪声及载波频率偏移两种情景下展开研究。针对全频率复用技术带来的波束间干扰问题,提出了以消除非期望用户的信号泄露为目的的最小化平均泄露功率预编码方法,并将平均SINR最大化鲁棒预编码方法作为对比。对于信道建模时考虑的不同噪声影响,分别分析了该预编码方法在不同情景下的应用,并对该方法的传输性能进行仿真,并得出所提预编码方法性能优异的结论。为消除多波束多用户卫星通信系统中单个波束内多个用户之间的干扰,提出了一种基于联合调制的预编码方法,即,发送端联合调制与预编码对信号序列进行预处理,引入取模运算并设计算法直接得到发送信号。在一维坐标情形和二维坐标情形中,分别将该方法在单波束多用户SIMO系统中的应用推广至多波束多用户MIMO系统,并对该方法的传输性能进行仿真,得出该方法可有效消除单个波束内用户间干扰的结论。更多还原

【Abstract】 With the development of the internet,users have put forward various requirements for communication services such as cross-regional,multimedia,real-time interaction,interconnection of all things,etc.The communication industry is committed to the development of high-speed and large-capacity communication system.The high-throughput multi-beam satellite communication system gradually replaces the traditional satellite communication and becomes the development trend of the current satellite communication.Considering that the multi-beam satellite communication system is similar in structure to the terrestrial MIMO communication system,full frequency reuse technology is introduced to improve frequency band utilization,expand communication capacity and alleviate the dilemma of tight frequency band resources.This thesis analyzes the wireless transmission channel between satellite and ground mobile terminal.Aiming at the influence of multipath effect,shadow effect,doppler frequency shift,weather influence and ionospheric scintillation on the transmission performance of satellite mobile communication transmission channel,the fading characteristics caused by these influencing factors are analyzed.Considering that in the transmission process of satellite mobile communication,these influencing factors lead to the uncertainty of the satellite mobile channel,but the channel has statistical characteristics in a certain period of time,so this thesis gives four different satellite statistical channel models,including the Loo model,Corazza model,Lutz model and Rice shadow model.In addition,the fading factors considered in the channel modeling in this thesis are clarified,and the channel model used in this thesis is derived based on the classical satellite channel model.In this thesis,a system model of multi-beam satellite MIMO transmission is built.According to different influencing factors,the research is carried out in two scenarios,which only consider phase noise and consider phase noise and carrier frequency offset.Aiming at the problem of inter-beam interference caused by full frequency reuse technology,a precoding method that minimizes average leakage power is proposed to eliminate the signal leakage of undesired users,and the average SINR maximizing robust precoding method is compared.For the different noise effects considered in channel modeling,the application of the precoding method in different scenarios is analyzed,and the transmission performance of the method is simulated,and the conclusion that the precoding method proposed in this thesis has excellent performance is obtained.In order to eliminate the interference between multiple users in a single beam in a multi-beam multi-user satellite communication system,this thesis proposes a precoding method based on joint modulation,that is,the transmitter performs joint modulation and precoding to preprocess the signal sequence,and introduce the modulo operation and design the algorithm to get the transmitted signal directly.In the case of one-dimensional coordinates and two-dimensional coordinates,the application of this method in single-beam multi-user SIMO system to multi-beam multi-user MIMO system is respectively extended,and the transmission performance of the method is simulated,and it is concluded that the method can be conclusions for effectively eliminating inter-user interference within a single beam.更多还原