介绍19种典型强度调制方式的符号结构,推导它们在高斯信道、弱湍流信道、中强湍流信道中的误时隙率(SER)模型,并进行了数值仿真。仿真结果表明:随着信噪比不断增大,各调制方式的SER持续减小并逐渐趋于一致,当SER趋于一致时,对信噪比的要求随湍流强度的增大而增高。脉冲位置调制(PPM)在三种信道中的SER均为最小;调制阶数较小时,差分幅度PPM的SER最大,调制阶数较大时,开关键控(OOK)的SER最大。其余调制方式的SER介于OOK、PPM与差分幅度PPM之间,并随着调制阶数的增大出现分层现象。研究结果对实际激光通信系统的设计具有一定参考价值。

In this paper, the symbolic structures of 19 typical intensity modulation schemes are introduced, and their slot error rate (SER) models in a Gaussian channel, weak-turbulence channel, and moderate-turbulence channel are derived and numerical simulations are performed. The results show that with the increase in the signal-to-noise ratio (SNR), the SER of each modulation mode initially decreases, but then, gradually plateaus. When SER stabilizes, the SNR requirement increases with the increase in turbulence intensity. The SER of pulse position modulation (PPM) is the smallest in all three channels. When the modulation order is small, the SER of differential amplitude PPM is the largest, and when the modulation order is large, the SER of on-off keying(OOK) is the largest, while SERs of the other methods are in-between, arranged hierarchically as the modulation order increases. These research results will serve as a reference for the design of practical laser communication systems.