# Dual-IRS Aided Near-/Hybrid-Field SWIPT: Passive Beamforming and Independent Antenna Power Splitting Design

## TL;DR

This paper introduces a dual-IRS aided SWIPT system with independent antenna power splitting, optimizing phase shifts and beamforming in near- and hybrid-field scenarios to enhance energy harvesting and information transfer.

## Contribution

It develops a novel dual-IRS SWIPT framework with independent PS, models near- and hybrid-field channels, and proposes optimization algorithms for improved system performance.

## Key findings

- Significant energy harvesting gains demonstrated.
- Optimization algorithms outperform benchmarks.
- Channel invariance simplifies hybrid-field optimization.

## Abstract

This paper proposes a novel dual-intelligent reflecting surface (IRS) aided interference-limited simultaneous wireless information and power transfer (SWIPT) system with independent power splitting (PS), where each receiving antenna applies different PS factors to offer an advantageous trade-off between the useful information and harvested energy. We separately establish the near- and hybrid-field channel models for IRS-reflected links to evaluate the performance gain more precisely and practically. Specifically, we formulate an optimization problem of maximizing the harvested power by jointly optimizing dual-IRS phase shifts, independent PS ratio, and receive beamforming vector in both near- and hybrid-field cases. In the near-field case, the alternating optimization algorithm is proposed to solve the non-convex problem by applying the Lagrange duality method and the difference-of-convex (DC) programming. In the hybrid-field case, we first present an interesting result that the AP-IRS-user channel gains are invariant to the phase shifts of dual-IRS, which allows the optimization problem to be transformed into a convex one. Then, we derive the asymptotic performance of the combined channel gains in closed-form and analyze the characteristics of the dual-IRS. Numerical results validate our analysis and indicate the performance gains of the proposed scheme that dual-IRS-aided SWIPT with independent PS over other benchmark schemes.