Release Date：2022-03-16 Author：XU Yongjun, YANG Zhaohui, HUANG Chongwen, YUEN Chau, GUI Guan Click：
Resource Allocation for Two-tier RIS-Assisted Heterogeneous NOMA Networks
XU Yongjun1, YANG Zhaohui2, HUANG Chongwen3, YUEN Chau4, GUI Guan5
(1. School of Communication and Information Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065, China;
2. Department of Electronic and Electrical Engineering, University College London, WC1E 6BT London, UK;
3. College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China;
4. Engineering Product Development Pillar, Singapore University of Technology and Design, Singapore 487372, Singapore;
5. College of Telecommunications and Information Engineering, Nanjing University of Posts and Telecommunications, Nanjing 210003, China)
Abstract: Reconfigurable intelligent surface (RIS) as a promising technology has been proposed to change weak communication environments. However, most of the current resource allocation (RA) schemes have focused on RIS-assisted homogeneous networks (HetNets), and there is still no open work about RA schemes of RIS-assisted heterogeneous networks (HetNets). In this paper, we design an RA scheme for a RIS-assisted HetNet with non-orthogonal multiple access to improve spectrum efficiency and transmission rates. In particular, we jointly optimize the transmit power of the small-cell base station and the phase-shift matrix of the RIS to maximize the sum rates of all small-cell users, subject to the unit modulus constraint, the minimum signal-to-interference-plus-noise ratio constraint, and the cross-tier interference constraint for protecting communication quality of microcell users. An efficient suboptimal RA scheme is proposed based on the alternating iteration approach, and successive convex approximation and logarithmic transformation approach. Simulation results verify the effectiveness of the proposed scheme in terms of data rates.
Keywords: heterogeneous networks; non-orthogonal multiple access; reconfigurable intelligent surface; resource allocation
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