Fluid Antenna Multiple Access Assisted Integrated Data and Energy Transfer: Outage and Multiplexing Gain Analysis

TL;DR

The paper tackles integrating fluid antenna based fast access with IDET in a downlink system where a BS with N fixed antennas serves N UEs each equipped with a K-port fluid antenna, coordinated by PS to balance data and energy transfer. It develops exact and approximate outage expressions for WDT and WET under Rayleigh fading for two port-selection strategies (SINR-maximizing for WDT and EHP-maximizing for WET), and extends the framework to Rician channels to include LoS effects. It then defines special and general IDET outages and corresponding multiplexing gains, and analyzes energy efficiency, providing closed-form approximations that reveal how N, W, and K influence performance and the WDT/WET trade-off. Numerical results validate the theory, showing meaningful trade-offs and practical guidelines, including how larger FA size and more BS-UE pairs can improve energy harvesting while potentially degrading data transfer due to interference, and demonstrating the applicability of the approach in Rician environments. The work thus offers a rigorous, tractable framework for designing FAMA-assisted IDET systems with PS coordination and provides actionable insights for selecting the number of UEs, fluid antenna size, and port counts in practical deployments.

Abstract

Fluid antenna multiple access (FAMA) exploits the spatial opportunities in wireless channels to overcome multiuser interference by position (a.k.a.~port) switching, which can achieve better performance compared to traditional fixed multiple-input multiple-output (MIMO) systems. Additionally, integrated data and energy transfer (IDET) is capable of providing both wireless data transfer (WDT) and wireless energy transfer (WET) services towards low-power devices. In this paper, a FAMA-assisted IDET system is investigated, where a base station (BS) equipped with $N$ fixed antennas provides dedicated IDET services towards $N$ user equipments (UEs). Each UE is equipped with a single fluid antenna, while the power splitting (PS) approach is conceived for coordinating WDT and WET. The outage probabilities of both WDT and WET are derived and approximated into closed-forms, where the fluid antenna (FA) at each UE selects the optimal port to achieve the maximum signal-to-interference-plus-noise ratio (SINR) or the energy harvesting power (EHP). The IDET outage probabilities are defined and subsequently derived and approximated into closed-forms. Further, multiplexing gains of the proposed system are defined and analyzed to evaluate the performace. Numerical results validate the theoretical analysis, while also illustrate that the trade-off is achieved between WDT and WET performance by exploiting different port selection strategies. Furthermore, the number of UEs should be optimized to achieve better IDET performance of the system.

Figures (13)

• Figure 1: An FAMA-assisted IDET system.
• Figure 2: Outage probabilities versus $N$.
• Figure 3: WDT outage probability with the WET oriented port selection strategy versus $N$.
• Figure 4: WET outage probability with the WDT oriented port selection strategy versus $N$.
• Figure 5: Multiplexing gains of WDT and WET versus $N$; $\gamma_{\text{th}}=3$ dB and $Q_{\text{th}} = 14$ mW.

Theorems & Definitions (18)

• Theorem 1
• Corollary 1
• Remark 1
• Theorem 2
• Lemma 1
• Corollary 2
• Remark 2
• Theorem 3
• Remark 3
• Theorem 4