多用户协作NOMA系统中的最优中继选择策略

Optimal Relay Selection Strategy in Multiuser Cooperative NOMA System

在多用户协作非正交多址接入(NOMA)系统中,针对传统中继转发方式单一,中断性能较差的问题,提出了一种基于混合译码/放大转发(HDAF)协议的改进式最优中继选择策略.该策略以中继能否成功解码信号为依据,将多个中继划分为DF候选中继子集与AF候选中继子集,并选出其中接收信噪比最高的中继参与协作.为了进一步提升系统的通信性能,本文还引入自动重传(ARQ)技术,提出了一种基于增量混合译码/放大转发(IHDAF)协议的中继选择策略.分别推导了两种策略下系统中断概率的闭式表达,并通过蒙特卡罗实验对不同策略的中断概率进行了仿真.结果表明,本文所提的两种策略相比于传统策略能够获得更低的中断概率,特别是IHDAF中继选择策略始终可以实现更佳的中断性能.

In multiuser cooperative Non-Orthogonal Multiple Access(NOMA)system,an improved optimal relay selection strategy based on Hybrid Decoding/Amplifying and Forwarding(HDAF)protocol was proposed to solve the problems of the single forwarding mode and poor outage performance in traditional relays.Based on whether the relay can decode the signal successfully,the strategy divides multiple relays into DF candidate relay subset and AF candidate relay subset,and selects the relay with the highest SNR to participate in the cooperation.In order to further improve the communication performance of the system,this paper also introduces anAuto RepeatreQueat(ARQ)technology and proposes a relay selection strategy based on Incremental Hybrid Decoding/Amplifying and Forwarding(IHDAF)protocol.The closed expressions of the outage probability for the two strategies are deduced respectively,andMonte Carlo experiments are performed to simulate the outage probability of the different strategies.The results show that the two strategies proposed in this papercan achieve lower outage probability than the traditional strategies,especially the IHDAF relay selection strategy can always achieve better outage performance.