Reconfigurable intelligent surface (RIS) as a promising technology has been proposed to change weak communication environ-ments. However, most of the current resource allocation (RA) schemes have focused on RIS-assisted homogeneous networks, and there is still no open works 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 ap-proach, and successive convex approximation and logarithmic transformation approach. Simulation results verify the effectiveness of the pro-posed scheme in terms of data rates.

XU Yongjun;YANG Zhaohui;HUANG Chongwen;YUEN Chau;GUI Guan

School of Communication and Information Engineering,Chongqing University of Posts and Telecommunications,Chongqing 400065,China;Department of Electronic and Electrical Engineering,University Col-lege London,London WC1E 6BT,UK;College of Information Science and Electronic Engineering,Zhejiang University,Hangzhou 310027,China;Engineering Product Development Pillar,Singapore University of Technology and Design,Singapore 487372,Singapore;College of Telecommunications and Information Engineering,Nanjing University of Posts and Telecommunications,Nanjing 210003,China

中兴通讯技术（英文版）

[1]XU Yongjun;YANG Zhaohui;HUANG Chongwen;YUEN Chau;GUI Guan-.Resource Allocation for Two-Tier RIS-Assisted Heterogeneous NOMA Networks)[J].中兴通讯技术（英文版）,2022(01):36-47

microcell

Resource,Allocation,Two,Tier,RIS,Assisted,Heterogeneous,NOMA,Networks,Reconfigurable,intelligent,surface,promising,technology,been,proposed,change,weak,communication,environ,ments,However,most,current,resource,allocation,RA,schemes,have,focused,assisted,homogeneous,networks,there,still,open,about,heterogeneous,HetNets,In,this,paper,design,orthogonal,multiple,access,improve,spectrum,efficiency,transmission,rates,particular,jointly,optimize,transmit,power,small,station,phase,shift,matrix,maximize,sum,users,subject,unit,modulus,constraint,minimum,signal,interference,plus,noise,cross,tier,protecting,quality,An,efficient,suboptimal,alternating,iteration,successive,convex,approximation,logarithmic,transformation,approach,Simulation,results,verify,effectiveness,terms,data

0.601966