Reconfigurable intelligent surface enhanced MISO‐OFDM anti‐jamming communications: Joint active and passive precoding design

Abstract

The reconfigurable intelligent surface (RIS) fundamentally changes the existing antijamming paradigm by reconstructing the wireless propagation environment. However, the existing RIS-based anti-jamming work mainly considers narrow-band frequency-flat fading channels. As an extension of existing work, the use of RIS to enhance the antijamming capability of broadband orthogonal frequency division multiplexing (OFDM) system in frequency-selective fading channels is first studied. In the multipath frequencyselective fading channels, the anti-jamming design needs to satisfy the channel gains of all signal paths with different delays. To this end, the authors propose a joint design scheme of active precoding at the transmitter and passive precoding at the RIS to attenuate the jamming signal and enhance the legitimate signal, and formulate the joint design objective to maximize the average rate of all subcarriers. An alternating optimization algorithm is developed to address this non-convex problem due to the complex coupling of active and passive precoding. In detail, the active and passive precoding are solved by the Cauchy-Schwarz inequality and power water-filling method and the alternating direction method of multipliers method assisted by multidimensional complex quadratic transform, respectively. Simulation results demonstrate that the proposed method can significantly improve the anti-jamming communication performance of the OFDM system compared with the scheme without RIS. In addition, the impact of the number of RIS elements and deployment location on system performance is revealed.

Controllable Multiple Active Reconfigurable Intelligent Surfaces Assisted Anti-Jamming Communication

“…And define the tolerable error ξ, the number of algorithm cycles N to ensure the robustness of the algorithm. And in step 2, calculate γ 0 through (2). Continuously update the optimization variable P, A, f, v, x, γ in steps 3 to step 11 until it converges or reaches the number of cycles.…”

“…Building upon the aforementioned advantages, RIS has been widely adopted to enable anti-jamming communication by jointly optimizing the beamforming of the base station (BS) and the phase shifts of RIS, enhancing the desired signals while eliminating the jamming signals [2][3][4]. An anti-jamming method was proposed in [2], in which the transmitting beam and RIS phase shift were joint optimized. Furthermore, the performance of RIS-assisted wireless communication under the conditions of simultaneous jamming and eavesdropping attacks was studied in [5,6].…”

Multi‐agent reinforcement learning based transmission scheme for IRS‐assisted multi‐UAV systems

“…This can significantly improve the signal‐to‐noise ratio (SNR) [14]. Additionally, IRS can establish a virtual line‐of‐sight (LoS) path between the signal transmitter and receiver to improve the communication environment [15]. In most existing studies on IRS‐assisted communication, the IRS is typically placed on the surface of tall buildings or ceilings.…”