Log-likelihood ratio calculation for iterative decoding on Rayleigh fading channels using Pade approximation
Log-likelihood ratio calculation for iterative decoding on Rayleigh fading channels using Pade approximation
复制标题
使用 Pade 近似计算瑞利衰落信道迭代解码的对数似然比
DOI：
10.1155/2013/970126
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
Gou Hosoya and Hiroyuki Yashima
中科院分区：
文献类型：
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作者：
梶山 祐一;林 直樹;高井 重昌;グェン トゥワンハン;Gou Hosoya and Hiroyuki Yashima
提出了一种基于Padé近似的无线信道对数似然比（LLR）的近似计算方法。LLR被用作诸如低密度奇偶校验（LDPC）码或turbo码的强大纠错码的迭代解码的输入。由于缺乏对无线衰落信道（例如不相关平坦瑞利衰落信道）的信道状态信息的了解，对于实际实现，这些信道的精确LLR的计算是相当复杂的。以前的工作，使用泰勒近似的LLR计算，很快变得不准确，因为信道输出留下一些导数点。当采用高阶调制方案时，这成为一个大问题。为了克服这个问题，一个新的LLR近似使用Padé近似，它表示的原函数的有理形式的两个多项式具有相同的泰勒级数的系数总数，可以加速泰勒近似，设计。将该方法应用于迭代译码和几种调制方式的LDPC码，通过仿真结果和基于密度演化的分析，验证了该方法的有效性。
Approximate calculation of channel log‐likelihood ratio (LLR) for wireless channels using Padé approximation is presented. LLR is used as an input of iterative decoding for powerful error‐correcting codes such as low‐density parity‐check (LDPC) codes or turbo codes. Due to the lack of knowledge of the channel state information of a wireless fading channel, such as uncorrelated fiat Rayleigh fading channels, calculations of exact LLR for these channels are quite complicated for a practical implementation. The previous work, an LLR calculation using the Taylor approximation, quickly becomes inaccurate as the channel output leaves some derivative point. This becomes a big problem when higher order modulation scheme is employed. To overcome this problem, a new LLR approximation using Padé approximation, which expresses the original function by a rational form of two polynomials with the same total number of coefficients of the Taylor series and can accelerate the Taylor approximation, is devised. By applying the proposed approximation to the iterative decoding and the LDPC codes with some modulation schemes, we show the effectiveness of the proposed methods by simulation results and analysis based on the density evolution.