Fluid Antenna System For Anti-jamming Communication via Fast Port Switching

Abstract

The fluid antenna system (FAS) holds big promise in wireless communications due to the ability of reconfiguring the antenna position to enhance the spatial diversity. In this paper, we propose an anti-jamming communication scheme that exploits the FAS to combat a malicious jammer, which intentionally sends jamming signals to interfere with the legitimate receiver. In contrast to the conventional anti-jamming communication schemes that rely on antenna arrays to mitigate the unintentional signals, the proposed scheme uses the FAS at the receiver side which has multiple open ports sharing a single radio frequency chain. By rapidly switching the active port, the FAS receives multiple different faded signals which can be carefully combined to improve the desired signal strength and suppress the jamming signals. Considering the practical imperfections of the jamming channel, we formulate a worst-case achievable rate maximization problem by jointly designing the transmit beamforming and the receive combining coefficients, subject to the general power constraints. We derive the semi-closed form solutions to the formulated non-convex problem, which remarkably reduces the computational complexity. Numerical results demonstrate the proposed scheme is robust to channel imperfection, and the achievable rate outperforms that of the conventional fixed-position antenna schemes which have multiple antennas and multiple radio frequency chains.