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为了提高低密度扩展(LDS)系统性能对LDS多用户检测算法进行研究,提出了一种LDS非正交多址系统中多用户检测和信道编码译码联合迭代的方案.将各用户低密度奇偶校验码(LDPC)译码后的软信息回传给多用户检测器,提高了多用户符号检测的可靠性,而多用户检测性能的提高又进一步提高了LDPC码译码的性能.在相同条件下与多用户检测和LDPC码译码单独进行的方案进行了仿真对比,结果表明,联合迭代算法明显改善了误比特率,系统负载越大,联合迭代带来的性能改善也越大.同时,联合迭代还缩小了不同用户误码性能的差异且即使在系统负载达到200%时,误码性能也与单用户的性能相差不大.联合迭代算法在不增加接收机计算复杂度的情况下,显著提升了LDS系统的性能.
In order to improve the system performance of LDS, this paper proposes a multi-user detection algorithm based on multi-user detection in LDS non-orthogonal multi-access system, and proposes a combined iterative scheme of multi-user detection and channel coding and decoding in LDS system. The soft information decoded by LDPC is transmitted back to the multi-user detector to improve the reliability of multi-user symbol detection, and the improvement of multi-user detection performance further improves the performance of LDPC code decoding. The simulation results show that the joint iterative algorithm improves the bit error rate significantly, and the larger the system load, the greater the performance improvement caused by the joint iteration. , The joint iteration also reduces the difference between the performance of different users and even if the system load reaches 200%, the bit error performance and single-user performance is not much difference.The joint iterative algorithm without increasing the computational complexity of the receiver , Significantly improving the performance of the LDS system.