M-QAM调制下高空平台OFDM光链路误码性能

BER performance for HAP OFDM optical link with M-QAM

针对Gamma-Gamma分布大气湍流效应、几何传播损耗和指向误差联合效应对空间激光链路性能的影响,研究了高空平台OFDM光链路通信模型的误码性能。建立了基于M-QAM调制的高空平台OFDM光链路通信模型,获得了OFDM光链路的载波噪声比,推导出总平均误码率的闭合表达式。仿真分析了在不同大气湍流强度、QAM调制阶数、抖动标准差和波束宽度等参数条件下,链路误码率与发射功率的关系。研究结果表明,在弱湍流条件或归一化抖动标准差小于0.6时,增大发射功率对链路误码率性能的改善程度较为缓慢;不同QAM调制阶数或归一化波束宽度条件下,增大发射功率对链路误码率性能的改善程度不明显。

Aiming at the combined effects of the Gamma-Gamma atmosphere turbulence, geometric spread and pointing errors on space optical links, the bit error rate （BER） performance of the high altitude platform （HAP） OFDM optical communication link is investigated.The HAP OFDM optical communication link model based on M-QAM is built, and the electrical carrier to noise ratio for OFDM optical communication link is obtained.The closed form mathematical expression for the total average BER performance is theoretically derived.The relationship between the BER performance and the transmitted optical power under different parameters such as the atmosphere turbulence, the normalized jitter standard deviation and the normalized beam-width is analyzed by simulation.The results show that, the BER performance is obviously improved by increasing the transmitted optical power when the atmosphere turbulence condition is weak, or when the normalized jitter standard deviation is less than 0.6.On the other hand, no obvious improvement of the BER performance is obtained by increasing the transmitted optical power under different M-QAM or normalized beam width.