基于迭代处理的PCMA混合信号解调/译码算法

摘要

针对成对载波多址信号的分离,在实现信道参数估计且完成干扰抵消的基础上,该文利用信道编码信息提出一种联合线性最小均方误差(Minimum Mean-Square Error,MMSE)均衡和软译码的迭代解调/译码算法.该算法在均衡过程中利用译码后反馈的先验统计量来改善解调性能,重点研究了均衡与译码间的信息交互以及参数估计误差对解调性能的影响.仿真结果表明,对子码为(64,57,4)扩展BCH码的Turbo乘积码(Turbo Product Codes,TPC),采用QPSK调制且误比特率为10-3时,经过2次迭代能获得近4 dB的信噪比增益；采用8PSK调制且s/N0大于20 dB时,经过2次迭代能将误比特率至少提升2个数量级.%To separate the Paired Carrier Multiple Access (PCMA) signals, a joint linear Minimum Mean-Square Error (MMSE) equalization and soft decoding iteration demodulation/decoding algorithm is proposed in this paper, which is based on the realization of the channel parameters estimation and the interference cancellation. In the course of equalization, the algorithm exploits the feedback prior statistics after decoding to improve the performance of demodulation, with special emphasis on the information interaction between equalization and decoding and the impact of the parameters estimation error on the performance of demodulation. Simulation results show that, with Turbo Product Codes (TPC) codes whose subcode is (64,57,4) expand BCH codes, a gain of about 4 dB in signal-noise ratio can be obtained after two iterations for QPSK signals at a bit error rate of 10-3; Moreover, the bit error rate can be promoted by at least two orders of magnitude after two iterations, when 8PSK modulation is exploited and Es /N0 is more than 20 dB.