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基于双伽马(Gamma-Gamma)大气湍流信道,研究了采用脉冲位置调制(PPM)技术的无线光通信系统的误码率(BER)性能。推导出平均EBR的闭合表达式,该表达式适用于任意湍流强度和任意调制阶数,与数值积分相比,可显著提高计算速度。对于给定的平均EBR,对比分析了在不同湍流条件下PPM调制阶数与平均发射功率需求间的关系。结果表明,在无湍流高斯信道和弱湍流信道下,增加调制阶数可以减小平均发射功率需求;然而随着湍流的增强这种作用逐渐减小,在强湍流区,甚至出现了调制阶数越高,平均发射功率需求越大的现象。因此,在实际系统设计时,应考虑可能的湍流环境,再选择合适的调制阶数。
Based on the Gamma-Gamma atmospheric turbulence channel, the bit error rate (BER) performance of a wireless optical communication system using pulse position modulation (PPM) technique is studied. The closed expression of average EBR is deduced. The expression is suitable for arbitrary turbulence intensity and arbitrary modulation order, which can significantly improve the computational speed compared with numerical integration. For a given average EBR, the relationship between the modulation order of PPM and the average transmit power requirement under different turbulence conditions is comparatively analyzed. The results show that under the turbulent flow regime, the modulation order can reduce the average transmit power requirement. However, with the enhancement of turbulence, this effect decreases gradually. In the turbulent regime, even the modulation order The higher the average transmit power demand, the greater the phenomenon. Therefore, the actual system design should consider the possible turbulence environment, and then select the appropriate modulation order.