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为了逼近多址接入信道的容量限,对功率与低密度校验阵(LDPC)码的度分布进行了优化.基于互信息最大化准则设计了功率分配算法,并得出分配方案,利用高斯近似来近似取得因子图上消息的概率密度函数,得到功率分配条件下优化的LDPC码的度分布.采用迭代的检测与译码算法进行多址干扰的消除.仿真结果表明,经功率和LDPC码优化后的误码性能在误码率为10-5时比等功率只优化LDPC码度分布时的性能提升了1.6 dB.
In order to approximate the capacity limit of multiple access channels, the power and low density parity check matrix (LDPC) code degree distribution is optimized.According to the mutual information maximization criterion, a power allocation algorithm is designed and the allocation scheme is obtained. Gaussian Approximation to approximate the probability density function of the message on the factor graph to obtain the degree distribution of the optimized LDPC code under the power allocation condition.Iterative detection and decoding algorithm is used to eliminate the multiple access interference.The simulation results show that the power and LDPC code The optimized bit error rate performance is 1.6 dB higher than that of the case of equal-power optimized LDPC code-rate distribution at bit error rate of 10-5.