阈值系统中的LDPC译码随机共振及应用研究

摘要

The effects of stochastic resonance (SR) of low density parity check (LDPC) code decoding in the threshold array system are studied The source array coded by LDPC adds independent identically distributed Gauss noise through threshold array system.At the receiving end a BP iterative decoding algorithm is used and a bit error ratio is used as measurement.The simulation results demonstrate that when the signal is subthreshold,the bit error ratio firstly declines and then rises,as the noise intensity increases,showing the SR does exits.Especially,when the number of threshold devices is larger,SR is obvious.However,when the signal is suprathreshold,the noise cannot improve the decoding performance,SR does not occur in this case.The improving effects of LDPC decoding performance on the threshold array system under rice noise are studied and the existence of supra-threshold stochastic resonance (SSR) is confirmed.Finally,the noise effects on the transmission performance of the image in the LDPC coding and decoding system are studied.Results show that the improving noise effects on nonlinear system channel decoding can expand the application of SR in the channel decoding.%研究阈值阵列系统中低密度奇偶校验码(LDPC)的译码随机共振现象.经过LDPC编码调制的信源序列通过阈值阵列系统添加独立同分布的高斯噪声,接收端采用BP迭代译码算法,译码性能以误码率为测度.仿真结果表明,当信号是阈下时,噪声强度增加,误码率先降后增,随机共振发生,且在阈值单元个数较多时,随机共振现象越明显;当信号是阈上时,噪声总是恶化译码的性能,随机共振不存在.进而研究莱斯噪声作用下的译码随机共振现象,并发现存在阈上随机共振.最后推广到图像在LDPC编译码系统中传输的实际应用中,证实了噪声对其传输效果的明显改善作用.这些结果显示了非线性系统信道译码中噪声的改善作用,扩展了随机共振在信道译码中的应用.