Cable-Aided Distributed Reconfigurable Intelligent Surface (CRIS): New Paradigm for Wireless Communication Networks

Abstract

Reconfigurable intelligent surfaces (RISs) have been introduced to improve the coverage of wireless systems and make the communication environment controllable. The functionality of RIS is based on signal manipulation, in particular reflection, which can be used to steer the electromagnetic waves in the preferred directions. Accordingly, the spatial diversity and signal quality can be enhanced via nearly passive beamforming. Nevertheless, wireless propagation of the signals from the transmitter to the RIS and then to the receiver can still experience a substantial path loss and delay. In this work, we introduce a novel concept of cable-aided distributed RIS (CRIS), which seamlessly connects two distant locations and thus enables superior signal propagation conditions compared to state-of-art technologies. In combination with the techniques known in the context of RIS, such as beamforming, spatial diversity enhancement, etc., this technology can provide unprecedented improvements for the coverage and energy efficiency of future wireless networks. Furthermore, the communication environment is expected to become not just controllable, but partially transparent. The obtained numerical results indicate that CRIS outperforms both the traditional RISs and the recently proposed STAR-RISs with simultaneous transmission and reflection capabilities, while the operation requirements and complexity for CRIS are much lower compared to the latter.