On HARQ-IR for Downlink NOMA Systems
On HARQ-IR for Downlink NOMA Systems
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DOI：
10.1109/tcomm.2016.2585651
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发表时间：
2016-06
影响因子：
8.3
通讯作者：
Jinho Choi
中科院分区：
文献类型：
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作者：
Jinho Choi
非正交多址接入（NOMA）可以利用用户之间的功率差来实现更高的频谱效率。因此，功率分配在NOMA中起着至关重要的作用。本文研究了NOMA中两用户混合自动重传请求（HARQ）的功率分配问题。对于功率分配，我们认为在HARQ的中断概率的误差指数与增量冗余（IR），并推导出它们的基础上大的偏差。虽然没有干扰的误差指数（或速率函数）的闭合形式表达式是可用的，但是没有干扰的误差指数的闭合形式表达式。因此，本文主要研究误差指数的下界。基于错误指数，我们制定了一个功率分配问题，HARQ-IR在NOMA，以保证一定的低中断概率为给定的最大数量的重传。从仿真结果中，我们可以确认，它是可能的，以保证一定的中断概率所提出的功率分配方法。
Non-orthogonal multiple access (NOMA) can exploit the power difference between the users to achieve a higher spectral efficiency. Thus, the power allocation plays a crucial role in NOMA. In this paper, we study the power allocation for hybrid automatic repeat request (HARQ) in NOMA with two users. For the power allocation, we consider the error exponents of the outage probabilities in HARQ with incremental redundancy (IR) and derive them based on large deviations. While a closed-form expression for the error exponent (or rate function) without interference is available, there is no closed-form expression for the error exponent with interference. Thus, we focus on the derivation of a lower bound on the error exponent in this paper. Based on the error exponents, we formulate a power allocation problem for HARQ-IR in NOMA to guarantee a certain low outage probability for a given maximum number of retransmissions. From the simulation results, we can confirm that it is possible to guarantee a certain outage probability by the proposed power allocation method.