Asymptotic max-min SINR analysis of reconfigurable intelligent surface assisted MISO systems

Qurrat Ul Ain Nadeem, Abla Kammoun, Anas Chaaban, Mérouane Debbah, Mohamed Slim Alouini

Research output: Contribution to journalArticlepeer-review


This work focuses on the downlink of a single-cell multi-user system in which a base station (BS) equipped with M antennas communicates with K single-antenna users through a reconfigurable intelligent surface (RIS) installed in the line-ofsight (LoS) of the BS. RIS is envisioned to offer unprecedented spectral efficiency gains by utilizing N passive reflecting elements that induce phase shifts on the impinging electromagnetic waves to smartly reconfigure the signal propagation environment. We study the minimum signal-to-interference-plus-noise ratio (SINR) achieved by the optimal linear precoder (OLP), that maximizes the minimum SINR subject to a given power constraint for any given RIS phase matrix, for the cases where the LoS channel matrix between the BS and the RIS is of rankone and of full-rank. In the former scenario, the minimum SINR achieved by the RIS-assisted link is bounded by a quantity that goes to zero with K. For the high-rank scenario, we develop accurate deterministic approximations for the parameters of the asymptotically OLP, which are then utilized to optimize the RIS phase matrix. Simulation results show that RISs can outperform half-duplex relays with a small number of passive reflecting elements while large RISs are needed to outperform full-duplex relays.

Original languageEnglish (US)
Article number2986438
Pages (from-to)7748-7764
Number of pages17
JournalIEEE Transactions on Wireless Communications
Issue number12
StatePublished - Dec 2020


  • Reconfigurable intelligent surface (RIS)
  • asymptotic analysis
  • multiple-input single-output (MISO) system
  • projected gradient ascent
  • random matrix theory (RMT)

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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