Two-Stage Superposed Transmission for Cooperative NOMA Systems
Two-Stage Superposed Transmission for Cooperative NOMA Systems
复制标题
DOI：
10.1109/access.2017.2789193
复制
发表时间：
2018-01
期刊：
影响因子：
3.9
通讯作者：
Wei Duan;Xueqin Jiang;Miaowen Wen;Jue Wang;Guoan Zhang
中科院分区：
文献类型：
--
作者：
Wei Duan;Xueqin Jiang;Miaowen Wen;Jue Wang;Guoan Zhang
提出了一种用于协作非正交多址（NOMA）系统的两级叠加传输方案。在前$N$时隙中，源端同时向中继端和目的端发送叠加编码符号，中继端和目的端不进行解码，而是保留接收。在最后一个时隙，中继对具有相应功率分配因子的新叠加编码符号进行解码并转发到目的地。目的端采用最大比值组合的方法，对总共$N + 1$时隙内接收到的信号进行联合解码。在瑞利衰落信道条件下，考虑高发射信噪比的情况，研究了系统的遍历和率、中断概率和中断容量。以可忽略的性能损失为代价，推导出遍历SR的近似表达式。数值结果表明，该方案的传输速率和遍历频率优于时分多址和传统的NOMA方案。
In this paper, a two-stage superposed transmission scheme for cooperative nonorthogonal multiple access (NOMA) systems is proposed. During the first $N$ time slots, the source simultaneously transmits the superposition coded symbols to the relay and destination, both of which, instead of decoding, keep the receptions in reserve. At the last time slot, the relay decodes and forwards a new superposition coded symbol with corresponding power allocation factors to the destination. The destination jointly decodes the received signals during the total $N + 1$ time slots by employing maximum ratio combining. Assuming Rayleigh fading channels, the ergodic sum rate (SR), outage probability, and outage capacity of the system are investigated considering the high transmit signal-to-noise ratio cases. An approximate expression for the ergodic SR is also derived at the expense of a negligible performance loss. By means of numerical results, it is shown that the transmission rate and ergodic SR of the proposed scheme overwhelm that of the time-division multiple access and conventional NOMA schemes.