部分外部信息传递的SCMA多用户检测算法

摘要

To deal with the huge burden to the function node (FN) in each decoding iteration in sparse code multiple access (SCMA) by using message passing algorithm (MPA),this paper first derives some statistical observation for the probability density function of received signals at various signal to-noise ratios (SNRs) by using the Monte Carlo method.Then based on a detailed analysis between the probability density function value of received signals and external information values,a threshold decision scheme is introduced into MPA,therefore a partial extrinsic information transmission of MPA (PEIT-MPA) is proposed.Simulation results show that the proposed PEIT-MPA efficiently relieves the implementation complexity of MPA,especially at the case of high SNR,meanwhile keeps the bit error ratio and convergence rate from degrading noticeably.%针对稀疏码分多址(sparse code multiple access,SCMA)采用消息传递算法(message passing algorithm,MPA)进行迭代解码中,功能节点(function node,FN)工作负担过重的问题,首先采用蒙特卡罗法得到了接收信号概率密度函数值在不同信噪比(signal-to-noise ratio,SNR)下的统计规律,然后针对接收信号概率密度函数值与外部信息值的关系,提出了基于门限判决减少FN负荷的部分外部信息传递的(partial extrinsic information transmission,PEIT)消息传递算法(PEIT-MPA).仿真结果表明,PEIT-MPA在几乎不改变系统误比特率和迭代收敛速度的条件下,降低了MPA复杂度,且SNR越高时,PEIT-MPA复杂度越低.