空频联合索引调制系统中子载波优化算法

在空频联合索引调制系统中,针对用于索引调制的所有子载波组合大于所需子载波组合的情况,提出一种改进的子载波优化算法,解决子载波组合冗余的问题。该算法首先通过汉明距离(Hamming distance)之和最大与最多优质组合准则选出最优子载波组合,然后根据最优映射准则修改索引比特与子载波之间的映射方式,将索引比特映射到最优子载波组合上。当所需子载波组合数较多时,提出一种基于格雷码的二分法来解决最优映射中复杂度较高的问题。结果表明:当误码率为10~(-3)时,改进算法相较于传统算法获得了约0.5 dB的增益。

Subcarrier Optimization Method in Space-Frequency Joint Index Modulation System

As a new modulation technique, space-frequency join index modulating system reduces the sensitivity of the system to frequency offset on the sparsity of the symbols sent by the transmitter, eliminates part of the inherent interference, and parameter configuration is very flexible. However, the problem of subcarrier combination redundancy still exists. An improved subcarrier optimization algorithm is proposed for solving this problem. Firstly, the optimal subcarrier combination is selected according to the largest and maximum quality combination criteria of the sum of Hamming distances, and then the mapping between the index bits and the subcarriers is modified according to the optimal mapping criterion, and the index bits are mapped to the optimal subcarrier combination. When the number of required subcarrier combinations is large, a bisection method based on Gray code is proposed to solve the problem of high complexity in the optimal mapping. The experimental analysis and simulation results show that the algorithm can improve the bit error rate of the system effectively.