卫星时变MIMO信道下的传输策略

Transmission Strategy Under Satellite Time-varying MIMO Channel

多输入多输出(Multiple Input Multiple Output,MIMO)技术是提高卫星通信频谱效率的关键手段之一。为了应对卫星MIMO信道存在的信道退化、信道模糊等现象,提出了一种基于Keyhole信道模型的迫零(Zero⁃Forcing,ZF)传输策略。通过预编码将每路数据流分别调整到其他数据流的发射信号空间的正交空间上,从而防止干扰,获得自由度增益。还提出基于信道统计特性的功率分配原则以及预编码设计准则,进一步提升系统容量,降低信道模糊的影响。仿真结果表明,相比于单路数据流策略和V⁃BLAST策略,ZF传输策略在信道自由度分别为1和2的情况下获得次优容量,而在高信噪比时,则可以获得最优期望容量。同时,功率分配原则以及预编码设计准则能进一步提高ZF传输策略下的容量和系统稳定性。

Multiple input multiple output(MIMO)technology is a key approach to improve the spectrum efficiency of satellite communication.To deal with channel degradation and channel ambiguity in satellite MIMO channels,this paper proposes a zero-forcing(ZF)transmission strategy based on a Keyhole channel model.Each data stream is adjusted to the orthogonal space of the transmitted signal space of other data streams through precoding,thereby preventing interference and obtaining freedom gain.A power allocation principle and a precoding design principle based on the statistical characteristics of the channel are also proposed to further increase the system capacity and reduce the impact of channel ambiguity.Simulation results show that,compared with the single-channel data stream strategy and the V-BLAST strategy,the ZF transmission strategy achieves sub-optimal capacity when the channel degrees of freedom is 1 and 2 respectively,and it achieves optimal expected-capacity at a high SNR.Meanwhile,the power allocation principle and precoding design principle can further improve the capacity and system stability under the ZF transmission strategy.