湍流信道中的分层光空间调制

Layered Optical Spatial Modulation in Turbulent Channels

将分层技术引入光空间调制中,同时激活两个分别采用脉冲位置调制(PPM)和脉冲幅度调制(PAM)的激光器,构建一种适用于湍流信道的分层光空间调制(LOSM)系统。在详细介绍系统中层映射和比特映射原理的基础上,推导出分层光空间调制系统的误码率表达式,并利用蒙特卡罗仿真进一步验证了该方案的正确性。结果表明,与传统光空间调制系统相比,分层光空间调制系统可大大提高系统的频谱效率。在传输速率相同的情况下,(5,4,2,4)-LOSM系统的频谱效率是(8,4,16)-SPPM (空间脉冲位置调制)系统的9倍以上;当频谱效率为4 bit·s^-1·Hz^-1时,(5,4,2,4)-LOSM系统与(8,4,2)-SPAM(空间脉冲幅度调制)系统具有相同的误码性能,但前者的传输速率几乎是后者的2倍。

Layered spatial modulation technique is introduced into free space optical communications. A layered optical spatial modulation(LOSM) system suitable for turbulent channels is proposed by simultaneously activating two lasers using pulse position modulation(PPM) and pulse amplitude modulation(PAM), respectively. The principle of layer mapping and bit mapping is described in detail, based on which the bit error rate expression of the proposed LOSM system is derived, and the Monte Carlo simulation is utilized to verify its reliability. The simulation results show that the LOSM system can greatly improve the spectral efficiency of the system. For example, the spectral efficiency of the(5,4,2,4)-LOSM system is more than 9 times that of the(8,4,16)-SPPM(spatial pulse position modulation) system for the same transmission rate. When the spectral efficiency is 4 bit·s^-1·Hz^-1, the transmission rate of the(5,4,2,4)-LOSM system is nearly twice that of the(8,4,2)-SPAM(spatial pulse amplitude modulation) system, and the two systems have the same bit error performance.