非规则LDPC码译码量化问题研究

对应用于国家数字电视地面传输标准的非规则LDPC码的log-BP译码算法实现中的量化问题进行研究,针对三种不同的编码效率的码字,对接收数据和中间变量进行均匀和变精度量化方案设计,并在高斯信道上仿真。通过对误码率和译码硬件复杂度两方面的对比和优化,得出了标准采用的LDPC码log-BP算法量化的实用性结论,作为硬件实现及其他应用的重要依据和参考。进一步指出对中间变量采用“变精度量化”方案,可使误码率非常接近无量化处理。

Quantization Issues for the Decoding of Irregular LDPC Codes

The quantization scheme of the iterative log-belief propagation(BP) algorithm for the irregular low-density parity-check(LDPC) codes adopted in the National Terrestrial Digital Television Broadcasting Transmission Standard is studied.The uniform and variable precision quantization schemes of the received data and mid-variables for three kinds of codes of different code rates are designed and simulated over the AWGN channel.By comparing and optimizing the error performance and hardware decoding complexity,useful conclusions are obtained as to the quantization issue of the log-BP algorithm for the further reference of the hardware implementation and other applications.Furthermore,we found that applying the variable precision quantization scheme to the mid-variables can improve the performance very closely to the infinite precision scheme.