级联RS码的自由空间光通信正交频分复用系统性能分析

为了有效抵御大气散射效应和提高频谱利用率，提出了自由空间光通信正交频分复用系统．由于大气信道的不稳定性，该系统在传输过程中导致误码率很高．将里德-所罗门码引入自由空间光通信正交频分复用系统中，对其进行了半实物仿真，仿真结果表明：当误码率为10^-2时，正交频分复用较开关键控性能优越4dB；在广延雨、平流雾、沙尘天等不同的天气条件下，当误码率为10^-5时，里德-所罗门（255，223）信道编码较未编码性能优越4～5dB．正交频分复用系统和里德-所罗门码的技术能降低系统的误码率．

Performance of the Free Space Othogonal-Frequency Division Multiplexing System Concatenated RS Codes

For the purpose of effective resisting of the atmospheric scattering and impoving of the spectrum utilization rate. Free space orthogonal frequency division multiplexing（FSO-OFDM） system is proposed. Due to the instability of the atmospheric channel, the system, which is still in the process of transmission, will be affected by various factors,resulting in a high error rate. Reed-Solomon（RS） code is applied to the FSO-OFDM system. At last, the semi-physical simulation has been conducted. The simulation results show that when the BER is 10^-2, the performance of orthogonal frequency division multiplexing（OFDM） is superior to 4 dB compared with OOK. In different weather conditions （extensa rain, advection fog, dust days）, when the BER is 10^-5, the performance of RS（225,223） channel coding is superior to 4 - 5 dB compared with uncoding. The results show that, OFDM system and RS code technology can reduce the system BER.