为了抑制大气湍流对大气光通信系统性能的影响，将低密度奇偶校验（LDPC）码与多输入多输出技术结合，推导了最大比合并、等增益合并和选择合并三种合并方式下单输入多输出(SIMO)系统译码初始化计算公式，并比较了系统误码性能。仿真结果表明，基于LDPC编码的大气光通信SIMO系统误码性能优于SISO系统；不同的方式下SIMO系统的误码性能不同， 信噪比一定时，最大比合并方式的系统误码率最低，等增益合并方式次之；在发射天线数一定时，随着接收天线数增加，系统误码率降低，对大气光通信的系统设计与理论研究具有一定的指导意义。

In order to reduce the influence of atmospheric turbulence on the performance of atmospheric optical communication system, low-density parity-check (LDPC) codes combined with multiple-input multiple-output technologies is applied. Decoding initialization formulas of single-input multiple-output (SIMO) system are derived in the forms of maximal ratio combining (MRC), equal gain combining (EGC) and selection combining, the system bit-error-rate (BER) performances are compared. The simulation results show that the atmospheric optical communication SIMO system of LDPC coding has better BER performance than that in SISO system; error performance of SIMO system differs with different combining schemes; the system in MRC has the lowest bit error rate followed by system in EGC with the same signal-to-noise ratio; with the increasing number of receiving antennas in a certain number of transmitting antennas, the BER will be decreased. So, it has some significance in the design of atmospheric optical communication system and theoretical research.