Low-Resolution RIS-Aided Multiuser MIMO Signaling

A. A. Nasir, H. D. Tuan, E. Dutkiewicz, H. V. Poor, L. Hanzo

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


A multi-antenna aided base station (BS) supporting several multi-antenna downlink users with the aid of a reconfigurable intelligent surface (RIS) of programmable reflecting elements (PREs) is considered. Low-resolution PREs constrained by a set of sparse discrete values are used for reasons of cost-efficiency. Our challenging objective is to jointly design the beamformers at the BS and the RIS's PREs for improving the throughput of all users by maximizing their geometric-mean, under a variety of different access schemes. This constitutes a computationally challenging problem of mixed continuous-discrete optimization, because each user's throughput is a complicated function of both the continuous-valued beamformer weights and of the discrete-valued PREs. We develop low-complexity algorithms, which iterate by directly evaluating low-complexity closed-form expressions. Our simulation results show the advantages of non-orthogonal multiple access-aided signaling, which allows the users to decode a part of the multi-user interference for enhancing their throughput.

Original languageEnglish (US)
Pages (from-to)6517-6531
Number of pages15
JournalIEEE Transactions on Communications
Issue number10
StatePublished - Oct 1 2022
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


  • MIMO beamforming
  • Reconfigurable intelligent surface
  • coordinated signaling (CoSig)
  • geometric mean maximization
  • low-complex algorithms
  • non-orthogonal multiple access (NOMA)
  • trigonometric function optimization


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