针对无线光通信脉冲位置调制(PPM)与信道纠错编码的有效结合问题，提出一种大气无线光通信乘积编码PPM新方案。将比特交织和迭代技术引入分组乘积编码PPM中，利用比特交织使信号衰落变得独立，并根据最大似然准则推导得到了弱湍流高斯级联信道下PPM软解调方法，将其与分组码的软输入软输出(SISO)译码算法相结合，进行解调译码的联合迭代。在弱湍流大气条件下仿真及分析表明，方案与独立解调解码的比特交织乘积编码PPM相比，在误码率10-5下有约1 dB的增益，且在高码率下可获得优异差错性能，有利于降低系统传输带宽需求并提供高可靠性的信息传输，为纠错编码与PPM的高效联合提供了解决方法。

There is a poor efficiency for pulse position modulation (PPM) in combination with binary correction coding for free space optical communication. To solve the problem, a new scheme, which introduces bit interleaving and iteration technology into product coded PPM, is proposed. Bit interleaver is used to make signal decline independently. Soft demodulation method of PPM is derived under weak turbulence and Gaussian cascaded channel based on maximum-likelihood criterion. Combined with soft input soft output (SISO) algorithm of block decoding, iteration between demodulation and decoding is achieved. Simulations under weak turbulence show that, the scheme provides 1 dB gain at bit errror rate (BER) of 10-5 compared with bit interleaved product coded PPM with independent demodulation and decoding, and has perfect error performance at high code rate, which is valuable in high reliability in information transmission with comparatively lower bandwidth requirement. The proposed scheme provides a solution to efficiently unite error control coding with PPM in atmospheric optical wireless communication systems.