Simultaneous Wireless Information and Power Transfer for Fluid Antenna Systems

TL;DR

This work addresses simultaneous wireless information and power transfer (SWIPT) in a MISO system by integrating multiple fluid antennas (FAs) at the transmitter and a fluid receive antenna at the energy receiver. It develops a field-response based channel model and formulates a nonconvex joint optimization of transmit covariance $\bm{Q}$, transmit FA positions $\bm{t}$, and receive FA position $\bm{r}$ to maximize harvested power under a SINR constraint at the information receiver. An alternating optimization framework decomposes the problem into convex subproblems for $\bm{Q}$, and surrogate-optimized updates for $\bm{r}$ and each $\bm{t}_n$ via successive convex approximation, resulting in a locally optimal solution. Numerical results show significant EH gains when using FAs in both transmit and receive regions, with performance improving as path counts increase and transmit power grows, highlighting the practical potential of FA-enabled SWIPT with optimized antenna positioning.

Abstract

Fluid antenna is a promising wireless communication technology that enhances communication rate by changing the antenna positions. This article proposes a new communication system that combines multiple-input single-output (MISO) fluid antennas with traditional fixed-position antennas, utilizing antenna position optimization to improve energy harvesting efficiency. In this model, we consider simultaneous wireless information and power transfer (SWIPT) which transmits identical signals from the base station to both information receiver (IR) and energy receiver (ER). We strive to enhance the power delivered to the ER by fine-tuning the positions of transmit and receive fluid antennas, along with optimizing the transmit covariance matrix, subject to a given minimum signal-to-interference-plus-noise ratio (SINR) constraint at the IR. Simulation results indicate that fluid antenna systems significantly enhance the energy harvesting efficiency of the ER compared to traditional fixed-position antennas.

Figures (4)

• Figure 1: A MISO fluid antenna system for dual information and energy transfer.
• Figure 2: Fluid antenna and fixed-position versus normalized region size.
• Figure 3: Energy harvesting at different powers versus normalized region size.
• Figure 4: FA systems with the number of transmit/receive paths $Lr = Lt = 14$, $Lr = Lt = 24$, versus normalized region size.