Beyond Max-SNR: Joint Encoding for Reconfigurable Intelligent Surfaces

Understand

A communication link aided by a Reconfigurable Intelligent Surface (RIS) is studied, in which the transmitter can control the state of the RIS via a finite-rate control link.

• Prior work mostly assumed a fixed RIS configuration irrespective of the transmitted information.
• In contrast, this work derives information-theoretic limits, and demonstrates that the capacity is achieved by a scheme that jointly encodes information in the transmitted signal as well as in the RIS configuration.
• In addition, a novel signaling strategy based on layered encoding is proposed that enables practical successive cancellation-type decoding at the receiver.