Hybrid Beamforming for Reconfigurable Intelligent Surface based Multi-user Communications: Achievable Rates with Limited Discrete Phase Shifts

Boya Di, Hongliang Zhang, Lingyang Song, Yonghui Li, Zhu Han, H. Vincent Poor

Research output: Contribution to journalArticle

Abstract

Reconfigurable intelligent surface (RIS) has drawn considerable attention from the research society recently, which creates favorable propagation conditions by controlling the phase shifts of the reflected waves at the surface, thereby enhancing wireless transmissions. In this paper, we study a downlink multi-user system where the transmission from a multi-antenna base station (BS) to various users is achieved by the RIS reflecting the incident signals of the BS towards the users. Unlike most existing works, we consider the practical case where only a limited number of discrete phase shifts can be realized by the finite-sized RIS. A hybrid beamforming scheme is proposed and the sum-rate maximization problem is formulated. Specifically, the continuous digital beamforming and discrete RIS-based analog beamforming are performed at the BS and the RIS, respectively, and an iterative algorithm is designed to solve this problem. Both theoretical analysis and numerical validations show that the RIS-based system can achieve a good sum-rate performance by setting a reasonable size of RIS and a small number of discrete phase shifts.

Original languageEnglish (US)
JournalIEEE Journal on Selected Areas in Communications
DOIs
StateAccepted/In press - 2020

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Electrical and Electronic Engineering

Keywords

  • Array signal processing
  • Base stations
  • Downlink
  • Hybrid beamforming
  • Iterative methods
  • Limited discrete phase shifts
  • Multi-user communications
  • Non-convex optimization
  • PIN photodiodes
  • Reconfigurable intelligent surface
  • Surface waves
  • Wireless communication

Fingerprint Dive into the research topics of 'Hybrid Beamforming for Reconfigurable Intelligent Surface based Multi-user Communications: Achievable Rates with Limited Discrete Phase Shifts'. Together they form a unique fingerprint.

  • Cite this