Location-Driven Beamforming for RIS-Assisted Near-Field Communications

TL;DR

This paper explores how location information can be exploited to improve near-field RIS-assisted wireless communications, addressing channel acquisition challenges at high frequencies like sub-THz bands for 6G.

Contribution

It introduces a location-driven beamforming scheme using a Fresnel zone model, advancing near-field RIS-assisted communication design and localization accuracy.

Findings

Location-driven beamforming enhances signal quality.

Fresnel zone model supports precise localization.

Numerical simulations validate the proposed scheme.

Abstract

Future wireless communications are promising to support ubiquitous connections and high data rates with cost-effective devices. Benefiting from the energy-efficient elements with low cost, reconfigurable intelligent surface (RIS) emerges as a potential solution to fulfill such demands, which has the capability to flexibly manipulate the wireless signals with a tunable phase. Recently, as the operational frequency ascends to the sub-terahertz (THz) bands or higher bands for wireless communications in six-generation (6G), it becomes imperative to consider the near-field propagation in RIS-assisted communications. The challenging acquisition of channel parameters is an inherent issue for near-field RIS-assisted communications, where the complex design is essential to acquire the informative near-field channel embedded with both the angle and distance information. Hence, in this paper we systematically investigate the potential of exploiting location information for near-field RIS-assisted communications. Firstly, we present the progresses in the near-field RIS-assisted communications, which are compatible with existing wireless communications and show the potential to achieve the fine-grained localization accuracy to support location-driven scheme. Then, the Fresnel zone based model is introduced, with which the location-driven beamforming scheme and corresponding frame structure are developed. Also, we elaborate on four unique advantages for leveraging location information in RIS-assisted communications, followed by numerical simulations. Finally, several key challenges and corresponding potential solutions are pointed out.