基于未对准衰落(即指向误差)和Malaga湍流分布的联合概率密度函数,采用Meijer G函数推导自适应多进制相移键控(MPSK)调制系统的平均误比特率和中断概率渐近表达式。接收机半径一定时,通过调整光束束腰半径和抖动标准差参数值,可获得系统最优误比特率。当束腰半径与接收机半径之比w_z/a=10且抖动标准差与接收机半径之比σ_s/a=1.5时,非自适应二进制相移键控(BPSK)系统平均误比特率曲线下降最快;而w_z/a=5,σ_s/a=1.5时,自适应MPSK系统频谱效率和平均误比特率均达到最优。当未对准衰落一定且平均电信噪比较小时,自适应系统平均误比特率和中断概率主要受未对准衰落影响,但随着平均电信噪比的增加,受湍流的影响增大。

Meijer G function is used to derive asymptotic expressions of average bit error rate and outage probability of adaptive M-ary phase-shift keying (MPSK) modulation system based on joint probability density function of misaligned fading (i.e., pointing error) and Malaga turbulence distribution. When receiver radius is fixed, the optimal bit error rate can be obtained by adjusting the beam waist radius and jitter standard deviation. When the ratio of the beam waist radius to the receiver radius is w_z/a=10 and jitter standard deviation to the receiver radius is σ_s/a=1.5, the average bit error rate curve of non-adaptive binary phase-shift keying (BPSK) system drops the fastest. The average bit error rate and spectral efficiency of the adaptive MPSK system are both optimal when w_z/a=5 and σ_s/a=1.5. When the misaligned fading is constant and average electric signal-to-noise ratio is small, the average bit error rate and outage probability of adaptive system are mainly affected by the misaligned fading, but with the increase in the average electric signal-to-noise ratio, the influence of turbulence increases.