Fluid Antenna System-Assisted Self-Interference Cancellation for In-Band Full Duplex Communications

2025-06-05

AI Summary

To address the challenges of residual self-interference (RSI) suppression and limited spectral efficiency in in-band full-duplex (IBFD) systems, this paper pioneers the integration of fluid antenna systems (FAS) into receive-side spatial self-interference cancellation (SIC). We propose a dynamic port selection–based SIC framework that jointly models spatial correlation among FAS ports. By leveraging this correlation, we derive a theoretical lower bound and an approximate analytical expression for the residual SI power, thereby overcoming fundamental performance limitations of conventional fixed-antenna SIC schemes. Simulation results demonstrate that RSI power decreases significantly with increasing FAS port count. Under realistic finite-scattering and wideband integrated access and backhaul (IAB) channel conditions, the proposed scheme achieves over 35% improvement in forward-link throughput and outperforms state-of-the-art SIC approaches in both RSI suppression and spectral efficiency.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Multiagent Systems: Agent Communication
• Intelligent Robots: State Estimation

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Data management and stream processing for Web, mobile and wireless applications
• Security and Privacy: Large-scale security measurements
• User Modeling, Personalization and Recommendation: Federated recommendation systems and personalization

Abstract

In-band full-duplex (IBFD) systems are expected to double the spectral efficiency compared to half-duplex systems, provided that loopback self-interference (SI) can be effectively suppressed. The inherent interference mitigation capabilities of the emerging fluid antenna system (FAS) technology make it a promising candidate for addressing the SI challenge in IBFD systems. This paper thus proposes a FAS-assisted self-interference cancellation (SIC) framework, which leverages a receiver-side FAS to dynamically select an interference-free port. Analytical results include a lower bound and an approximation of the residual SI (RSI) power, both derived for rich-scattering channels by considering the joint spatial correlation amongst the FAS ports. Simulations of RSI power and forward link rates validate the analysis, showing that the SIC performance improves with the number of FAS ports. Additionally, simulations under practical conditions, such as finite-scattering environments and wideband integrated access and backhaul (IAB) channels, reveal that the proposed approach offers superior SIC capability and significant forward rate gains over conventional IBFD SIC schemes.

Problem

• Suppress loopback self-interference in full-duplex systems
• Leverage fluid antenna for dynamic interference-free port selection
• Improve SIC performance with more FAS ports

Innovation

• FAS-assisted SIC framework
• Dynamic interference-free port selection
• Improved SIC with more FAS ports