为了克服光在弱湍流大气条件传输时，光强闪烁造成的突发错误，在已知信道衰落信息(CSI)和未知信道衰落信息(NCSI)条件下，研究了基于低密度奇偶校验(LDPC)码和二进制脉冲位置调制(BPPM)的无线光通信系统性能，论述了BPPM光通信信道对称性的特点，并与基于LDPC码和OOK调制的光通信系统性能进行了比较。结果表明，在NCSI和CSI情况下，基于LDPC码和BPPM的光通信系统相对于基于LDPC码和OOK调制的系统均有更优异的差错性能；在NCSI情况下，基于LDPC码和BPPM的光通信系统的性能相对于CSI情况下的系统性能损失并不大；且采用LDPC码BPPM相对于LDPC码OOK调制的光通信系统，随着湍流强度的增大系统性能损失较小。因此，基于LDPC码和BPPM的光通信系统在不需要信道衰落信息估计的情况下，能获得较大的编码增益，便于工程实现，在无线光通信中将有一定的应用前景。

Performance of optical wireless communication system based on binary pulse position modulation (BPPM) and low-density parity-check(LDPC) code through atmospheric turbulence channel was investigated in the both situations of perfect channel state information(CSI) and non-channel state information(NCSI)compared with LDPC coded optical wireless communication system based on on-off keying(OOK)with the same bite rate and the same average transmission power.Simulation results show that in the both situations of CSI and NCSI, optical wireless communication systems based on LDPC code and BPPM have more excellent bit error rate performance than that of LDPC coded optical wireless communication systems based on OOK, and when decoded with the average fading amplitude as an estimate of the NCSI channel, performance of optical wireless communication system based on LDPC and BPPM are not degraded too much compared to the CSI channel, and it was also found that LDPC coded optical wireless communication systems based on BPPM are less sensitive to turbulent intensity than the systems based on OOK. Therefore, in the situation of NCSI, LDPC coded optical wireless communication systems based on BPPM have excellent error correction capabilities and access to a larger coding gains，and the above scheme is well suited for optical wireless communication systems.