基于TPC的大气无线光通信差错性能分析

Analysis on Error Performance of Free Space Optical Communication Based on Turbo Product Code

为克服大气湍流引起的随机和深度衰落影响,将Turbo乘积码(TPC)引入无线光通信系统中。在构建大气无线光系统模型基础上,分析了TPC的抗突发错误能力,推导了弱湍流和高斯级联信道下接收信号的置信度度量计算方法,并对TPC编码前后大气无线光通信系统差错性能及不同参数的影响进行分析。结果表明,TPC可以有效补偿大气信道中的随机和深度衰落影响,使系统具有较强适应湍流变化的能力。为获得较高编码增益,TPC应首选高码率码型作为子码,同时兼顾纠错能力,迭代取34次时可较好平衡译码性能与复杂度。

Turbo product code （TPC） is introduced into free space optical communication （FSO） system to mitigate impact of random and long deep fade caused by atmospheric turbulence. After FSO system model is set up, the anti- burst error ability of TPC is studied. Also the algorithm of bit confidence measurement under weak turbulence and Gaussian cascaded channel is derived. The performances of TPC under weak turbulence and influential factors are analyzed. Simulations show that, TPC compensates the losses of random and deep fade effectively and makes coded FSO adapted to different turbulence conditions. To obtain more coding gain, the subcode of TPC should be insured high code rate as a priority, meanwhile its error correction ability should be considered. The number of iteration being 3-4 can achieve good balance between the performance and complexity.