In this article, we propose a downlink non-orthogonal multiple access (NOMA) based coordinated direct and relay system with one cell-center user and multiple cell-edge users, where a decode-and-forward (DF) relay bridges the connection between the base station and the cell-edge users. Both full-duplex (FD) and half-duplex (HD) protocols are considered for the relay. We assume that the performance of the cell-edge users is subjected to the relay, and the cancellation of the mutual interference between the relay and cell-center user is imperfect. Both the exact analytical expression of outage probability and an approximate expression of the ergodic sum rate at high signal-to-noise ratio (SNR) are derived. Numerical results demonstrate that: 1) the FD relaying NOMA system outperforms the HD relaying NOMA system at low SNR, but the situation is exactly the opposite at high SNR; 2) the mutual interference can cause a larger performance gap than the self-interference at the relay; 3) the power allocation coefficients for the cell-center user and relay can affect the performance more significantly than those for cell-edge users. 11 This article was presented in part at the IEEE International Workshop on Signal Processing Advances in Wireless Communications 2019 [1].

中文翻译：

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基于 NOMA 的协调直接和中继传输，具有半双工/全双工中继


在本文中，我们提出了一种基于下行链路非正交多址（NOMA）的协调直接和中继系统，具有一个小区中心用户和多个小区边缘用户，其中解码转发（DF）中继桥接之间的连接基站和小区边缘用户。中继同时考虑全双工 (FD) 和半双工 (HD) 协议。我们假设小区边缘用户的性能受到中继的影响，而中继与小区中心用户之间的相互干扰的消除并不完善。推导了断电概率的精确解析表达式和高信噪比（SNR）下遍历和率的近似表达式。数值结果表明：1）FD中继NOMA系统在低信噪比下优于HD中继NOMA系统，但在高信噪比下情况恰恰相反； 2) 中继处的相互干扰会比自干扰造成更大的性能差距； 3) 小区中心用户和中继的功率分配系数对性能的影响比小区边缘用户的功率分配系数更显着。 11 本文的部分内容是在 2019 年无线通信信号处理进展 IEEE 国际研讨会上发表的 [1]。