不同调制方式下光空时网格码性能分析

Performance Analysis of Optical Space Time Trellis Codes under Different Modulation Modes

空时网格码具有满分集和高编码增益,将其应用于大气激光通信系统中可以有效克服大气湍流对光通信系统的影响。在描述了湍流信道和光MIMO系统模型后,结合开关键控调制(OOK)、脉冲位置调制(PPM),分析采用不同调制方式下光空时网格码的误码性能,并通过蒙特卡洛仿真(Monte Carlo)进行性能分析。结果表明,在发射光功率相同的条件下,相对于OOK调制,PPM调制具有更高的光功率利用率,且当发射天线数固定时,光空时网格码的误码率随着接收天线数的增加而降低。

Space-time trellis codes have full diversity and high coding gain. By applying it to the atmospheric laser communication system, the effect of atmospheric turbulence on optical communication system can be effectively overcome. With description of turbulence channel and optical MIMO system model, and in combination of on-off keying （OOK） modulation with pulse position modulation （PPM）, the BER performance of optical space time trellis code with different modulation modes is analyzed and the performance analysis also done by through Monte Carlo simulation. Experiment results indicate that compared with OOK modulation, PPM modulation has even higher optical power utilization rate under same optical power, and that under the same emitter power, when the number of transmitting antenna is fixed, the bit error rate of the grid code is decreased with the increase of the number of receiving antenna.