现有光空间调制由于其传输速率与激光器数量呈对数关系,导致空间资源的利用率较低。因此,提出了一种完全光广义空间调制(F-OGSM)方案,该方案通过激活不同数量的激光器来传递信息,使传输速率和激光器数量之间呈线性关系。同时,为了充分利用激光器所有可能的组合,采用基于信道范数最大化选择算法完成了激活激光器的选择,有效改善了系统的误码性能。最后,利用蒙特卡罗仿真方法比较了F-OGSM以及现有光空间调制的性能。结果表明:相对于广义空间脉冲幅度调制而言,在激光器数量和调制阶数均为4时,F-OGSM系统的传输速率增加了1 bpcu;当误码率为1×10 ^-3时,采用激光器选择算法后F-OGSM系统所需信噪比改善了4 dB。可见,F-OGSM作为一种高速率的调制技术非常适用于未来大气激光通信。

Owing to the logarithmic relation between the transmission rate and number of lasers of existing spatial modulation, the usage of spatial dimension is low. To address this challenge, a fully optical generalized spatial modulation (F-OGSM) system was proposed, in which different number of lasers was activated for transmitting information to achieve a linear relation between the transmission rate and number of lasers. Furthermore, to fully utilize all combinations of lasers, the channel norm maximization selection algorithm was used to select the active lasers, which effectively improved the system bit error rate(BER,R_BE) performance. Moreover, the Monte Carlo simulation method was used to compare the performance of F-OGSM and existing optical space modulation schemes. When both the number of lasers and modulation order were 4, the transmission rate of the F-OGSM system increased by 1 bpcu compared with the generalized spatial pulse amplitude modulation. When R_BE=1×10 ^-3, the required signal-to-noise ratio of the F-OGSM system improved by 4 dB after using the laser selection algorithm. Conclusively, the proposed F-OGSM system exhibits a high-speed scheme that is particularly suitable for future atmospheric laser communications.