Low-to-Zero-Overhead IRS Reconfiguration: Decoupling Illumination and Channel Estimation

Vahid Jamali, George C. Alexandropoulos, Robert Schober, H. Vincent Poor

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Most algorithms developed for the optimization of Intelligent Reflecting Surfaces (IRSs) so far require knowledge of full Channel State Information (CSI). However, the resulting acquisition overhead constitutes a major bottleneck for the realization of IRS-assisted wireless systems in practice. In contrast, in this letter, focusing on downlink transmissions from a Base Station (BS) to a Mobile User (MU) that is located in a blockage region, we propose to optimize the IRS for illumination of the area centered around the MU. Hence, the proposed design requires the estimation of the MU's position and not the full CSI. For a given IRS phase-shift configuration, the end-to-end BS-IRS-MU channel can then be estimated using conventional channel estimation techniques. The IRS reconfiguration overhead for the proposed scheme depends on the MU mobility as well as on how wide the coverage of the IRS illumination is. Therefore, we develop a general IRS phase-shift design, which is valid for both the near- and far-field regimes and features a parameter for tuning the size of the illumination area. Moreover, we study a special case where the IRS illuminates the entire blockage area, which implies that the IRS phase shifts do not change over time leading to zero overhead for IRS reconfiguration.

Original languageEnglish (US)
Pages (from-to)932-936
Number of pages5
JournalIEEE Communications Letters
Volume26
Issue number4
DOIs
StatePublished - Apr 1 2022

All Science Journal Classification (ASJC) codes

  • Modeling and Simulation
  • Computer Science Applications
  • Electrical and Electronic Engineering

Keywords

  • Intelligent reflecting surfaces
  • blockage area
  • channel estimation
  • illumination area
  • low-overhead design

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