一种多元LDPC-CPM优化方法及性能仿真分析

为了解决二元低密度奇偶校验(LDPC)码与高阶连续相位调制(CPM)级联的系统在卫星通信、深空通信方面传输性能不足的问题，提出了一种多元LDPC-CPM优化方法。首先采用多元LDPC码与高阶CPM串行级联形成多元LDPC-CPM系统获取更好的传输误码性能。其次考虑到多元LDPC码的传统译码算法复杂度过高，难以硬件实现的问题，设计了一种改进型的Mixed-Log-FFT-BP算法，通过去除加法与查表运算中对数似然比的求解，降低译码复杂度。最后针对多元LDPC-CPM系统涉及参数过多问题，提出一种性能逐步收敛的参数优化方法。仿真结果表明，与优化前的系统相比，优化后的系统在中高信噪比下，误码性能有1～1.2 dB的提升，且系统复杂度较低。

A multivariate LDPC-CPM optimization method and performance simulation analysis

In order to solve the problem of insufficient transmission performance in satellite communication and deep space communication in the system of cascaded binary low-density parity-check (LDPC) codes and high-order continuous phase modulation (CPM), a multivariate LDPC-CPM optimization method is proposed. Firstly, cascading to form a multivariate LDPC-CPM system achieves better transmission error performance. Secondly, considering that the problem of the traditional decoding algorithm of non binary LDPC codes is too complex and hard to implement in hardware, an improved Mixed-Log-FFT-BP algorithm is designed. The solution of the ratio reduces the decoding complexity. Finally, in view of the problem of too many parameters in multivariate LDPC-CPM system, a parameter optimization method with gradually convergent performance is proposed. The simulation results show that, compared with the system before optimization, the optimized system has a 1~1.2 dB improvement in the bit error performance under the medium and high signal-to-noise ratio and the system complexity is lower.