为了根据信道的时变特性来选择合适的空时编码方式, 结合正交空时分组码与分层空时码的优点, 并借鉴天线分组的多层空时编码原理, 提出了一种在自由空间光通信多输入多输出中4×4的自适应多层空时编码方案, 并用Monte Carlo法进行仿真研究。结果表明, 在一定的信噪比范围内, 采用自适应多层空时, 编码方案在保证一定误比特率的条件下, 能使数据传输速率达到最大化; 采用自适应调制方式能更有效地利用资源并提高数据的传输速率。

In order to select proper space-time coding mode according to the time-varying channel, a 4×4 adaptive multi-layer space-time coding scheme was proposed in free space optical-multiple input multiple output(FSO-MIMO) based on the multi-layer space-time coding theory of antenna groups, which concludes the advantages of both orthogonal space-time block codes(OSTBC)and layered space-time code(LSTC). Simulation was carried out with Monte Carlo method. The simulation shows within a certain signal-to-noise ratio(SNR) range, the data rate can maximized at specific level of bit error rate(BER) with adaptive multi-layered space-time coding scheme.