基于上/下行NOMA的卫星通信系统遍历容量分析

Ergodic Capacity Analysis of Uplink/Downlink NOMA-Based Satellite Communication System

卫星通信作为实现广域覆盖和泛在连接不可或缺的一种手段,在民航空管、应急通信等实际应用中扮演着重要的角色。为了提升卫星通信系统的频谱效率和传输速率,首先将点波束和非正交多址(Non-orthogonal multiple access,NOMA)技术相结合,提出了一种高效的上/下行NOMA传输方案。其次,在假设卫星链路服从阴影莱斯(Shadowed-Rician,SR)分布,同时接收端采用完美和非完美串行干扰消除(Successive interference cancellation,SIC)的情况下,推导出所提方案的卫星系统遍历容量闭合表达式。最后,仿真结果验证了理论分析的正确性以及所提方案相较于正交多址方案获得的性能提升,并进一步分析了信道衰落系数、功率分配系数和残余干扰程度等因素对系统遍历容量的影响。

As an indispensable solution for wide coverage and ubiquitous connectivity,satellite communication plays an important role in practical applications,including civilaviation air traffic management and emergency communication.To improve the spectral efficiency and transmission rate of satellite communication system,we propose an efficient uplink/downlink non-orthogonal multiple access(NOMA)transmission scheme combining spot beam with NOMA technology.Then,based on the assumption that the satellite links experience shadowed-Rician(SR)fading while the perfect and imperfect successive interference cancellation(SIC)are seperately adopted at receivers.We derive the closed-form expression for the ergodic capacity of the proposed scheme.Finally,simulation results are given to validate the theoretical analysis and the performance improvement compared to the orthogonal multiple access(OMA)scheme.The effects of various parameters are further revealed on the system performance,such as channel fading coefficient,power allocation fraction and residual interference level.