OOK通信中的软判决辅助ML信道估计和MAP检测

Soft decision aided ML estimation and MAP detection for OOK

为了研究自由空间光(free space optical,FSO)通信开关键控(on-off keying,OOK)系统的信号接收问题,提出一种FSO-OOK信号的接收方案。首先基于最大似然(maximum-likelihood,ML)原理提出一种软判决辅助(soft decision aided,SDA)ML信道估计方法;然后根据SDA-ML估计子进行逐符号最大后验概率(maximum a posteriori,MAP)检测。通过蒙特卡洛仿真试验,对比这种接收方案与传统方案的接收性能。结果表明,该方案的均方误差和误比特率在中高信噪比、任意发送信号先验概率的情况下优于传统方案,并接近理想估计和理想检测的误差性能下界。因此,基于SDA-ML估计子进行MAP逐符号检测的信号接收方案的信道估计结果准确,信号检测的抗衰落能力强,适用于FSO-OOK通信场景。

A FSO-OOK receiver was proposed with a view to studying the receiver of free space optical(FSO)communication using on-off keying(OOK).First,a soft-decision-aided maximum-likelihood(SDA-ML)channel estimation was formulated on the basis of ML principle algorithm.Then,the SDA-ML estimator was applied to conduct the symbol-by-symbol maximum a posteriori(MAP)detection.Finally,the performance of this receiver was compared with that of traditional methodsby virtue of Monte Carlo simulation.Results show that bothmean square error and bit error probability performance of this proposed method are superior to those of traditional methods,approximating the lower bound of error performance of ideal estimation and detection.Thus,the symbol-by-symbol MAP detection receiver based on SDA-ML estimator boasts accurate result of estimation and strong anti-fading ability,being applicable to FSO-OOK communication scenarios.