摘要
在空间光通信系统中,每个入射光脉冲都会发生脉冲展宽效应,导致时隙似然比计算时出现信息丢失,系统性能下降。文章基于PPM(脉冲相位调制)与LDPC(低密度奇偶校验码)迭代解调系统,研究了用时隙似然比加权的办法来补偿脉冲展宽带来的影响。针对服从指数分布与高斯分布两种情况的脉冲展宽,分别采用指数似然比补偿和高斯似然比补偿两种方法进行似然比计算。仿真结果表明,脉冲展宽服从标准差为0.46的高斯分布时,采用似然比补偿的方法可以使误码率性能提高1.3dB。在一定抖动范围内,高斯补偿和指数补偿具有很好的互换性。
In the space optical communication system, the pulse broadening effect during every incident light pulse may cause the information lost when calculating the likelihood ratio, which deteriorates the system performance. In this paper, we study the slot likelihood ratio weighted method to compensate of the effects of pulse broadening based on PPM and LDPC iterative demodulation system. When the pulse broadening obey exponential distribution and Gauss distribution, the likelihood ratio are calculated using both of the Gaussian compensation and exponential compensation. Simulation result shows that when the pulse broadening obey the 0.46 standard deviation of Gauss distribution, the likelihood ratio compensation method can improve the performance by I. 3 dB. Within a certain range jitter, Gaussian compensation and exponential compensation has a very good interchangeability.
作者
向劲松
肖刚
XIANG Jin-song XIAO Gang(Key Lab of Optical Fiber Communications Technology, Chongqing University of Posts and Telecommunications, Chongqing 400065,Chin)
出处
《光通信研究》
北大核心
2016年第4期60-62,71,共4页
Study on Optical Communications
基金
国家自然科学基金资助项目(61571072)
关键词
空间光通信
脉冲展宽
泊松信道
似然比补偿
space optical communication
pulse broadening
poisson channel
likelihood ratio compensation
