M-QAM调制下极化码的构造研究

摘要

研究了当采用最常用的M-QAM调制时极化码构造的问题.在M-QAM调制时无法确定极化码的码元噪声功率,从而导致无法有效地进行信道极化.针对该问题,对M-QAM调制符号中的每个比特进行了研究,得到所有调制符号对应的比特的变化规律,通过这一规律,可以将高阶调制信道分解为多个平行的并具有固定噪声功率的二进制输入子信道,使得极化码在M-QAM调制下的构造问题变为了常规的二进制输入信道下的构造问题,并以此实现了M-QAM调制时极化码的构造.针对常用的格雷映射下的M-PAM/M-QAM调制进行了设计并仿真,仿真结果显示该构造方法能明显地提升性能.%In this paper, the construction of polar codes with multiple quadrature amplitude modulation (M-QAM) modulation is studied. To solve the problem of the various noise power of the coded bits caused by M-QAM modulation, we propose a method to divide the channel of M-QAM modulation into a several of parallel binary-input channels with constant noise power so that the traditional construction method for binary-input channel is available for the M-QAM modulation case. We also give the design in detail for M-PAM/M-QAM modulation. Our numerical results show that the proposed scheme has good performance.