基于单源最优路径的NOMA中继选择与协作传输

目前，在非正交多址接入(non-orthogonal multiple access，NOMA)中继通信的研究中，中继用户的选择是随机的，并没有考虑中继节点之间信道条件的差异。为了得到信道条件较好的中继用户，提出一种基于单源最优路径的中继选择策略，从基站广播信号以用户为节点，设定信道参数，寻找最佳传输通路。当信号到达目标节点后，基站从目标节点处收集所有可达通路，通过对比各通路的信道参数，选出一条最好的传输通路。基于所提中继选择策略，在非机会式NOMA系统中，提出一种新的协作传输方法，该方法在中继传输过程中剔除了多余信号以降低信号间干扰。仿真结果表明，在相同条件下，采用所提策略的协作传输方法比随机中继选择用户中断概率更低，有效降低了系统复杂度。

NOMA relay selection and cooperative transmission based on single source optimal path

Current non-orthogonal multiple access (NOMA) relay communication uses the random relay selection strategy without considering the differences in channel conditions between relay nodes. In order to provide relay users with better channel conditions, a new relay selection strategy based on a single source optimal path is proposed. The strategy starts with the signal broadcasting from base stations and treats users as nodes. Channel parameters are configured to find the best transmission path. After the signal reaches the target node, the base station collects all the reachable paths and performs a comparison of the channel parameters to find the best transmission path. Combining the proposed strategy with non-opportunistic NOMA, a new cooperative transmission method is obtained. This method eliminates redundant signals during relay transmission, thus the inter-signal interference is reduced. Simulation results show that the proposed method can achieve lower user outage probability and system complexity than the random relay selection strategy under the same conditions.