短波差分跳频系统序列译码的性能分析

摘要

基于短波差分跳频系统,提出了一种适于该系统的序列译码方法,并设计了适合序列译码的G函数.在加性白高斯噪声(additive white Gaussion noise,AWGN)信道和频率非选择性瑞利慢衰落信道务件下,对其比特误码率Pb性能进行了理论分析与数值仿真.仿真结果表明差分跳频的频率之间的相关性使其系统获得了一定的误跳纠正能力;如对于可用频率数为4、每跳传输1 bit的差分跳频系统,在AWGN信道条件下,当信噪比约为10 dB时,序列译码的Pb可达到10-4,相对于逐符号译码的性能改善为2.5 dB;在瑞利信道条件下,当信噪比约为18 dB时,序列译码的Pb可达到10-3,相对于逐符号译码的性能改善为15 dB,相对于逐符号译码,在短波差分系统中使用序列译码方法的效果更优.%A new decoding method is introduced which is called sequential decoding, and a corresponding DHF G-fuction is proposed. In additive white Gaussion noise ( AWGN ) channel and frequency-nonselective Rayleigh slowly fading channel. the error bit rate (EBR) performance in HF differential frequency-hopping system is simulated as well as analyzed, and the results indicate that correlation between signal frequencys in HF differential frequency-hopping system makes the system obtain the capability of correcting error that results from faulty hopping. For example, for a system with 4 available frequencies and 1 bit per hop, the Pb is le-4 when the SNR is approximately 10 dB over AWGN channels, and the performance is improved up to 2. 5 dB compared with the symbol-bysymbol decoded method; while it is le-3 when SNR is approximately 18 dB over Rayleigh fading channels, and the performance is improved up t0 15 dB compared with the symbol-by-symbol decoded method. So, compared with the symbol-by-symbol decoded method, it is better to use sequential decoding in HF differential frequency-hopping system.