Secure Beamforming with Reconfigurable Intelligent Surfaces for Anti-Jamming UAV Communication Links

Abstract

The Unmanned Aerial Vehicle (UAV) communication links are highly prone to the deliberate jamming because of the dominant line-of-sight propagation and the open author to deployment conditions. Traditional procedures of anti-jamming on the grounds of power adaptation or frequency agility offer less protection against adaptive enemies. Reconfigurable Intelligible Surfaces (RIS) provide a mechanism of low power electromagnetic control that can reconfigure the channel of propagation to restore the better signal robustness. The current paper presents a safe beamforming scheme of RIS-aided communication between UAVs and the ground in the presence of active jamming. The geometric model of UAV and ground channels is a three dimensional model which takes into account the altitude-dependent path loss and Rician fading to characterise UAV and ground channels accurately. Direct transmission, RIS-reflected and malicious interference are explicitly modelled in the received signal model. An optimization maximising secrecy rate is developed with unit-modulus RIS phase, and UAV power of the transmitters. In order to address the ensuing non-convex problem, the alternating optimization algorithm is developed to simultaneously optimise UAV beamforming vectors and RIS phase shifts, including discrete phase quantisation to reflect realistic hardware constraints. The simulation outcome shows that the secrecy rate can be increased by up to 65 percent and reduction of interference by a large value than the conventional beamforming in the absence of RIS. Moreover, the viability of the proposed approach is proved by the complexity analysis and considerations of RF implementation. The findings make RIS-assisted secure beamforming an effective and practical anti-jamming method in next-generation is to be used in UAV communication systems.