Resource Allocation in Intelligent Reflecting Surface Assisted NOMA Systems
Resource Allocation in Intelligent Reflecting Surface Assisted NOMA Systems
复制标题
智能反射表面辅助 NOMA 系统中的资源分配
DOI：
10.1109/tcomm.2020.3016742
复制
发表时间：
2020-11-01
影响因子：
8.3
通讯作者：
Al-Dhahir, Naofal
中科院分区：
文献类型：
--
作者：
Zuo, Jiakuo;Liu, Yuanwei;Al-Dhahir, Naofal
研究了智能反射面（IRS）辅助非正交多址（NOMA）系统的下行链路通信。为了最大限度地提高系统的吞吐量，我们制定了一个联合优化问题的信道分配，解码顺序的NOMA用户，功率分配，和反射系数。该问题被证明是NP难的。针对这一问题，提出了一种新的三步资源分配算法。首先，通过多对一匹配算法解决信道分配问题。其次，考虑到IRS反射系数的设计，提出了一种低复杂度的译码顺序优化算法。第三，在给定信道分配和译码顺序的情况下，提出了一种联合优化算法来求解联合功率分配和反射系数设计问题。数值结果表明：i）在IRS的辅助下，所提出的IRS-NOMA系统在系统吞吐量方面优于没有IRS的传统NOMA系统; ii）所提出的IRS-NOMA系统实现了比IRS辅助的正交多址（IRS-OMA）系统更高的系统吞吐量; iii）仿真结果表明，通过仔细选择IRS的位置，可以提高IRS-NOMA和IRS-OMA系统的性能增益。
This article investigates the downlink communications of intelligent reflecting surface (IRS) assisted non-orthogonal multiple access (NOMA) systems. To maximize the system throughput, we formulate a joint optimization problem over the channel assignment, decoding order of NOMA users, power allocation, and reflection coefficients. The formulated problem is proved to be NP-hard. To tackle this problem, a three-step novel resource allocation algorithm is proposed. Firstly, the channel assignment problem is solved by a many-to-one matching algorithm. Secondly, by considering the IRS reflection coefficients design, a low-complexity decoding order optimization algorithm is proposed. Thirdly, given a channel assignment and decoding order, a joint optimization algorithm is proposed for solving the joint power allocation and reflection coefficient design problem. Numerical results illustrate that: i) with the aid of IRS, the proposed IRS-NOMA system outperforms the conventional NOMA system without the IRS in terms of system throughput; ii) the proposed IRS-NOMA system achieves higher system throughput than the IRS assisted orthogonal multiple access (IRS-OMA) systems; iii) simulation results show that the performance gains of the IRS-NOMA and the IRS-OMA systems can be enhanced via carefully choosing the location of the IRS.