Reconfigurable Intelligent Surfaces in 6G: Reflective, Transmissive, or Both?

Shuhao Zeng, Hongliang Zhang, Boya Di, Yunhua Tan, Zhu Han, H. Vincent Poor, Lingyang Song

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


Reconfigurable intelligent surfaces (RISs) have attracted wide interest from industry and academia since they can shape the wireless environment into a desirable form at low cost. In practice, RISs have three types of implementations: 1) reflective, where signals can be reflected to the users on the same side of the base station (BS), 2) transmissive, where signals can penetrate the RIS to serve the users on the opposite side of the BS, and 3) hybrid, where the RISs have a dual function of reflection and transmission. Most existing works focus on the reflective type RISs, and the other two types of RISs have not been well investigated. In this letter, a downlink multi-user RIS-assisted communication network is considered, where the RIS can be one of these types. We derive the system sum-rate, and discuss which type can yield the best performance under a specific user distribution. Numerical results verify our analysis.

Original languageEnglish (US)
Article number9365009
Pages (from-to)2063-2067
Number of pages5
JournalIEEE Communications Letters
Issue number6
StatePublished - Jun 2021
Externally publishedYes

All Science Journal Classification (ASJC) codes

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


  • Reconfigurable intelligent surfaces
  • sum-rate analysis
  • type selection


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