Energy Efficient Fluid Antenna Relay (FAR)-Assisted Wireless Communications

TL;DR

This paper introduces an energy-efficient fluid antenna relay system for wireless communications that enhances NLoS link performance by optimizing antenna positions and beamforming, outperforming traditional schemes in energy efficiency.

Contribution

It proposes a novel FAR-assisted communication system with joint optimization of antenna positions, power, and beamforming to improve energy efficiency in NLoS scenarios.

Findings

Achieves up to 23.39% higher EE than RIS schemes.

Achieves up to 39.94% higher EE than traditional AF relays.

Outperforms conventional schemes in simulation results.

Abstract

In this paper, we propose an energy efficient wireless communication system based on fluid antenna relay (FAR) to solve the problem of non-line-of-sight (NLoS) links caused by blockages with considering the physical properties. Driven by the demand for the sixth generation (6G) communication, fluid antenna systems (FASs) have become a key technology due to their flexibility in dynamically adjusting antenna positions. Existing research on FAS primarily focuses on line-of-sight (LoS) communication scenarios, and neglects the situations where only NLoS links exist. To address the issues posted by NLoS communication, we design an FAR-assisted communication system combined with amplify-and-forward (AF) protocol. In order to alleviate the high energy consumption introduced by AF protocol while ensuring communication quality, we formulate an energy efficiency (EE) maximization problem. By optimizing the positions of the fluid antennas (FAs) on both sides of the FAR, we achieve controllable phase shifts of the signals transmitting through the blockage which causes the NLoS link. Besides, we establish a channel model that jointly considers the blockage-through matrix, large-scale fading, and small-scale fading. To maximize the EE of the system, we jointly optimize the FAR position, FA positions, power control, and beamforming design under given constraints, and propose an iterative algorithm to solve this formulated optimization problem. Simulation results show that the proposed algorithm outperforms the traditional schemes in terms of EE, achieving up to $23.39\%$ and $39.94\%$ higher EE than the conventional reconfigurable intelligent surface (RIS) scheme and traditional AF relay scheme, respectively.