Fluid Antenna-Empowered Receive Spatial Modulation

TL;DR

This paper introduces a novel fluid antenna-based receive spatial modulation system that enhances performance through optimized port selection and low-complexity detection, demonstrating significant improvements over traditional methods.

Contribution

It proposes a new FA-RSM system with optimal and low-complexity port selection algorithms and detectors, advancing spatial modulation technology.

Findings

FA-RSM outperforms conventional RSM in simulations.

Port selection algorithms balance performance and complexity.

Activating more ports improves performance but with diminishing returns.

Abstract

Fluid antenna (FA), as an emerging antenna technology, fully exploits spatial diversity. This paper integrates FA with the receive spatial modulation (RSM) scheme and proposes a novel FA-empowered RSM (FA-RSM) system. In this system, the transmitter is equipped with an FA that simultaneously activates multiple ports to transmit precoded signals. We address three key challenges in the FA-RSM system: port selection, theoretical analysis, and detection. First, for port selection, an optimal algorithm from a capacity maximization perspective are proposed, followed by two low-complexity alternatives. Second, for theoretical analysis, performance evaluation metrics are provided for port selection, which demonstrate that increasing the number of activated ports enhances system performance. Third, regarding detection, two low-complexity detectors are proposed. Simulation results confirm that the FA-RSM system significantly outperforms the conventional RSM system. The proposed low-complexity port selection algorithms facilitate minimal performance degradation. Moreover, while activating additional ports improves performance, the gain gradually saturates due to inherent spatial correlation, highlighting the importance of effective port selection in reducing system complexity and cost. Finally, both proposed detectors achieve near-optimal detection performance with low computational complexity, emphasizing the receiver-friendly nature of the FA-RSM system.