A Joint Space-Frequency Anti-jamming Scheme Based on Reconfigurable Intelligent Surface

Abstract

Existing works on solving jamming signals within the receiving antenna's bandwidth are generally difficult to strike a balance between flexibility and effectiveness. To this end, we propose a joint space-frequency anti-jamming scheme. Considering the broadband response of the Reconfigurable Intelligent Surface (RIS), we innovatively exploit different spatial and frequency responses of the RIS to generate space-frequency filtering during the propagation of the jamming signal. We formulate a problem to design reflection coefficients of the RIS so the jamming signals will be attenuated, but the legitimate signal will be enhanced at the receiver. Then the problem is equiv-alently transformed into a quadratically constrained quadratic programming (QCQP) problem which can be efficiently solved. We also present a jamming suppression scheme when legitimate transmitter pilots are submerged. Simulation results show that the proposed joint space-frequency anti-jamming scheme consti-tutes an equivalent broadband band-stop filter to the jamming signal and has better resistance to strong jamming. Meanwhile, the anti-jamming ability will further increase with the number of RIS elements. As an equivalent space-frequency filter embedded in the wireless environment, the proposed scheme introduces a different filtering paradigm to collaborate with existing anti-jamming techniques effectively and reveal its potential in some military or civilian scenarios.