异步双卫星MIMO系统中的空时编码方案

双卫星多输入多输出（MIMO，Multiple-Input Multiple-Output）系统中不同路径间传播时延的差异会造成接收信号不同步。针对该系统中接收信号不同步问题，提出一种时间反转全码率全分集空时编码方案。该方案中对发送的符号序列进行空时编码后，利用交织改变符号向量发送的时间顺序并对发送数据进行分组。将其中一组数据进行时间反转并插入保护间隔，使接收机在信号不同步的情况下仍然能够获得全码率和全分集增益，同时保留低复杂度最优译码算法的适用性。仿真结果表明，与传统方案相比，提出的空时编码方案能够获得最优的性能。另外，系统采用高阶调制方式或信道条件较差时，该方案的性能增益更大。

Space-time coding in asynchronous dual-satellite MIMO systems

The received signals are asynchronous due to the different transmission delays in the dualsatellite multiple-input multiple-output (MIMO) system. Aiming to solve the asynchronism problem, a time reversal full-rate full-diversity space time coding scheme was proposed. The space-time code words were interleaved and divided into two groups after the transmitting symbols were space time coded. Then the symbol sequence in one group was time reversed and a guard interval was added between groups, which ensured that the full rate and full diversity gain could be achieved in the asynchronous dual-satellite MIMO system. Meanwhile, there was a low-complexity optimal decoding algorithm for the proposed scheme. The simulation results show that the proposed space time coding scheme can achieve better performance compared with the traditional schemes. And the performance gain is more considerable when the high-order modulation is employed or the channel is in the deep shadowing state.