基于2×2放大转发中继的混合RF/FSO系统性能分析

Performance of 2×2 AF relay-assisted RF/FSO communication system

基于放大转发中继方式,研究了2×2中继条件下混合RF/FSO航空通信系统性能。FSO链路服从适于孔径平均条件下的Exponentiated Weibull大气湍流分布模型,RF通信链路为Nakagami-m衰落信道。建立2×2中继混合RF/FSO通信系统模型,利用Meijers’G函数推导求出航空激光通信系统信噪比的概率分布函数及累积分布函数,进一步推导混合通信系统平均误码率和中断概率的闭合表达式。通过仿真分析了不同大气湍流强度、孔径尺寸和调制方式对平均误码率和误码率的影响。仿真结果表明,混合系统中断概率及误码率受湍流强度影响较大,孔径平均效应可有效改善混合RF/FSO传输系统的性能;固定增益中继方式下,混合RF/FSO系统性能主要由RF链路决定;在固定增益中继混合RF/FSO系统中起主要作用;可变增益中继混合RF/FSO系统中,具有较小信噪比的链路在对系统性能的影响起主要作用。

The performance of mixed Free Space Optical(FSO)/Radio Frequency(RF)airborne communication system based on amplify-and-forward 2×2 relaying is analyzed in the paper.The Nakagami-m fading channel is adopted for RF communication link and the FSO link undergoes the Exponentiated Weibull fading channel.The 2×2 relay-assisted mixed FSO/RF airborne communication system is established and the closed form expressions of probability density function(PDF)and cumulative distribution function(CDF)about equivalent signal-to-noise ratio(SNR)are derived by Meijer′s G function.Moreover,the expressions o average bit-error-rate and outage probability are obtained.The relationship between the BER performance and the SNR under different parameters such as the atmosphere turbulence,aperture size and modulation scheme are analyzed by simulation.