Channel Estimation With Reconfigurable Intelligent Surfaces—A General Framework

Optimally extracting the advantages available from reconfigurable intelligent surfaces (RISs) in wireless communications systems requires estimation of the channels to and from the RIS. The process of determining these channels is complicated when the RIS is composed of passive elements without any sensing or data processing capabilities, and thus, the channels must be estimated indirectly by a noncolocated device, typically a controlling base station (BS). In this article, we examine channel estimation for passive RIS-based systems from a fundamental viewpoint. We study various possible channel models and the identifiability of the models as a function of the available pilot data and behavior of the RIS…

• NS
  National Science Foundation

  Awards: ECCS-2030029, CNS-2107182
• NN
  National Natural Science Foundation of China

  Award: 61971088