一种用于SCMA系统的混合期望传播检测方法

A Hybrid Expectation Propagation Detection Method for SCMA Systems

作为一种新的非正交多址接入技术,稀疏码多址接入(Sparse Code Multiple Access,SCMA)被提出以支持大规模连接。基于稀疏因子图,SCMA利用低复杂度的消息传递算法(Message Passing Algorithm,MPA)来实现接近最优的多用户检测。但是,传统MPA的复杂度仍然很高。为了灵活地控制算法的复杂性,提出了一种混合期望传播检测算法用于SCMA检测,建立算法复杂度与信道阈值之间的关系,利用信道阈值控制算法复杂度。此外,将混合期望传播检测算法与消息回退机制相结合以提高性能。仿真结果表明,与其他检测方案相比,所提算法可以灵活地在算法性能和计算复杂度之间进行折衷。

As a novel non-orthogonal multiple access technology,sparse code multiple access(SCMA)is proposed to support massive connection.Based on the sparse factor graph,SCMA utilizes low-complexity message passing algorithm(MPA)to achieve near-optimal multi-user detection.However,the complexity of MPA is still high.In order to flexibly control the algorithm complexity,an improved hybrid expectation propagation(EP)detection method is proposed for SCMA detection.The relationship between the algorithm complexity and the channel threshold is established,and the channel threshold is utilized to control the algorithm complexity.Moreover,the combination of hybrid EP method with message damping method is considered to improve the performance.Simulation results show that the proposed algorithm achieves a commendable trade-off between performance and computational complexity compared with other schemes.