摘要
针对宏小区稀疏码分多址技术(sparse code multiple access,SCMA)系统上行链路中远近用户到达基站存在的用户时延问题,提出了按不同时延进行用户分组的异步检测算法,利用前后符号间相同的信息进行迭代,形成了一种基于连续传播的消息传递算法(message passing algorithm based on serial propagation,SP-MPA).另外,针对 MIMO-SCMA 系统中运用的部分边缘化检测算法造成的误码率性能下降的问题,还提出了一种基于动态阈值的部分边缘化消息传递算法(dynamic threshold partial marginalization algorithm,DTPM-MPA).仿真结果表明,SP-MPA有效降低了异步传输的符号干扰带来的高误码率,并且DTPM-MPA能够在计算复杂度与误码率之间做出灵活平衡.
Abstract
Aiming at the problem of delays of multiple users arriving at the base station in the uplink sparse code multiple access(SCMA)macro-cell system,asynchronous detection algorithms were proposed with users grouped according to different delays and the same information between symbols was utilized and iterated,forming a message passing algorithm based on serial propagation(SP-MPA).Besides,aiming at the problem of worse bit error rate caused by partial marginalization algorithm used in MIMO-SCMA system,dynamic threshold partial marginalization algorithm(DTPM-MPA)was proposed.The simulation results show that the high bit error rate caused by symbol interference of asynchronous transmission is effectively reduced with SP-MPA and a flexible balance between computing complexity and bit error rate is formed with DTPM-MPA.
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