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目前LTE体制已成熟,在卫星通信系统中应用LTE技术有利于星地一体化网络的发展。移动卫星系统在4G网络中成功应用的一个关键因素是设备和地面系统得到最大的通用性。一种有效的解决这个问题的方法是利用地面空中接口作为卫星空中接口的基础。由于3GPP(The 3rd Generation Partnership Project,第三代合作伙伴计划)LTE(Long Term Evolution,长期演进)标准是4G移动通信的主要技术方案之一,本文分析了3GPP LTE接口应用于卫星传输的可行性,提出了一些解决这个应用的技术方案。重点介绍了三种解决方案:1、TTI(Transmission Time Interval传输时间间隔)间交织技术,利用现有HARQ的灵活性打破缓变信道的相关性;2、降低PAPR(Peak-to-Average Power Ratio,峰均比),以增强OFDM波形对非线性失真的适应能力;3、针对卫星信道大时延特性采用的随机存取序列的设计。分析结果表明,在利用以上几种解决方法后,现有的LTE空中接口经过改进可以应用在卫星信道中。
At present, the LTE system is mature, and the application of LTE technology in the satellite communication system is beneficial to the development of a satellite-to-satellite integrated network. A key factor in the successful application of mobile satellite systems in 4G networks is the maximum versatility of equipment and ground systems. An effective solution to this problem is to use the terrestrial air interface as the basis for the satellite air interface. As the 3GPP (The 3rd Generation Partnership Project) Long Term Evolution (LTE) standard is one of the major technical solutions for 4G mobile communications, this paper analyzes the feasibility of applying the 3GPP LTE interface to satellite transmission , Put forward some technical solutions to solve this problem. Three solutions are mainly introduced: 1. Interleaving technology between TTI (Transmission Time Interval), utilizing the flexibility of the existing HARQ to break the relativity of the slowly changing channel. 2. Reducing PAPR (Peak-to-Average Power Ratio) , Peak-to-average ratio), in order to enhance the ability of OFDM waveform to adapt to the nonlinear distortion; 3, for the large delay characteristics of satellite channel random access sequence design. The analysis results show that the existing LTE air interface can be applied to satellite channels after being improved by using the above solutions.