摘要
大气随机信道对光信号产生影响,致使系统误码率增加,严重影响了通信系统的性能;LDPC码是目前已知的距离Shannon限最近的纠错码。介绍了π-旋转LDPC码的原理和编码方法;分析了基于雪崩光电二极管光电检测器输出的译码软信息的计算;仿真验证了在无线光通信系统中采用π-旋转LDPC码的系统性能。仿真结果表明,在无线光通信系统中采用LDPC纠错码,当误码率为10-6时,编码前后信号光子数大约节约了30个,提高了系统的抗干扰能力,改善了系统性能。
The laser signal pulse was corrupted in the random atmosphere channel, so the error increase, and the system performance will be impaired seriously. Low-Density Parity-Check PC） codes are the error - correcting code, and its rates are extremely near to the Shannon codes （ LD- Firstly, the basic principle and the encoding method of the ,π- rotation LDPC code are introduced ; Secondly, calculating the soft information of decoding which is based on the output model of the avalanche photodiode demodulator was analyzed. Lastly, the numerical simulations test and verify system performance of the π - rotation LDPC codes in wireless optical communication system. The results show that the π -rotation LDPC error -correcting codes can improve the system performance remarkably, and the number of signal photons can decrease 30 averagely at BER（ Bit Error Rate） is 10^-6.
出处
《无线通信技术》
2008年第4期28-33,共6页
Wireless Communication Technology
关键词
无线激光通信
LDPC
PPM
wireless optical communication system
LDPC
pulse position modulation
