Maximum-Rate Optimization of Hybrid Intelligent Reflective Surface and Relay Systems

TL;DR

This paper proposes an optimized hybrid IRS-relay system for wireless communication, maximizing data rates by jointly designing power, beamforming, and IRS configurations, demonstrating superior performance over other schemes.

Contribution

It introduces a novel hybrid IRS-relay scheme with joint optimization of system parameters to enhance data rates in multi-antenna wireless systems.

Findings

Hybrid scheme outperforms non-hybrid schemes in achievable rate.

Optimal IRS configurations significantly improve system performance.

Joint optimization of power, beamformers, and IRS is effective for rate maximization.

Abstract

We consider a wireless communication system, where a transmitting source is assisted by both a reconfigurable intelligent reflecting surface (IRS) and a decode-and-forward half-duplex relay (hybrid IRS-relay scheme) to communicate with a destination receiver. All devices are equipped with multiple antennas, and transmissions occur in two stages. In stage 1, the source splits the transmit message into two sub-messages, transmitted to the destination and the relay, respectively, using block diagonalization to avoid interference. Both transmissions will benefit from the IRS. In stage 2, the relay re-encodes the received sub-message and forwards it (still through the IRS) to the destination. We optimize power allocations, beamformers, and configurations of the IRS in both stages, in order to maximize the achievable rate at the destination. We compare the proposed hybrid approach with other schemes (with/without relay and IRS), and confirm that high data rate is achieved for the hybrid scheme in case of optimal IRS configurations.