With deployment of 5G and emerging 6G networks, the demand of wireless communication for transmission capacity as well as the transmission security in consumer electronics is increasing. Reconfigurable intelligent surface (RIS) has shown a great potential in physical layer security (PLS) due to its enabling technology to engineer the radio signal prorogation. In this paper, we study PLS problems of RIS-assisted wireless communication system, where the RIS is deployed to aid pair of the transmitter (Alice) and receiver (Bob) under the active jamming (Jammer) and eavesdropper (Eve) attack. Different from traditional RIS schemes, our proposed scheme divides the RIS into two parts which not only enhances the legitimate user performance but also suppresses the eavesdropper. Specifically, the location of the jammer is also considered with two different scenarios, i.e., the distance between the jammer and RIS is smaller/greater than that of the one between the transmitter and RIS. Considering the influence of RIS reflection coefficient, path loss and uncertain jammer locations, we analyze the system performance based on the legitimate and eavesdropping channels, providing the upper and lower bounds of achievable received signal-to-noise ratio (SNR) instead of the secrecy outage probability (SOP). In addition, the simulation and asymptotic results reveal the location influence of the interference on the secrecy performance and the superiority of the proposed scheme.

This article presents an in-depth examination of aerial reconfigurable intelligent surface (ARIS) technology, an innovative development in wireless communication networks facilitated by unmanned aerial vehicles (UAVs). ARIS introduces a dynamic approach to augmenting communication links, particularly vital in environments characterized by rapid change and complexity. We focus on key technical aspects such as the strategic 3D placement of ARIS for optimal signal coverage, intricate real-time channel estimation techniques, and the engineering challenges in hardware implementation. A detailed case study demonstrates the application of ARIS in a UAV-mounted relay system, aimed at enhancing the signal range and quality between a terrestrial base station and multiple ground users. This investigation encompasses the technical nuances of deploying ARIS, with an emphasis on the optimization of beamforming algorithms, evaluation of environmental influences on ARIS's operational stability and signal integrity, and a comparative analysis of beamforming strategies under variable operational parameters. The results underscore the efficacy of ARIS in elevating terrestrial network performance, offering technical strategies to address UAV-related dynamism and environmental variability. Additionally, the article explores diverse applications of ARIS, underscoring its critical role in scenarios spanning from emergency communications to advanced urban network infrastructure.

This letter explores the potential of reconfigurable intelligent surface (RIS) to enhance vehicle-to-vehicle (V2V) communications under predictable mobility conditions. We analyze the impact of multipath fading and Doppler effects induced by high-mobility vehicles on the proposed system. Moreover, we present a Pareto optimal RIS configuration design aimed at maximizing power gain while simultaneously mitigating Doppler shifts and multipath spread. Our approach leverages predictable vehicle trajectory information instead of relying on instantaneous channel state information (CSI) to achieve optimal performance. Numerical results vividly demonstrate the clear superiority of our proposed RIS phase shift design over the benchmark method.

In this paper, we derive new analytic expressions for the atmospheric-induced frequency spread of optical plane and spherical waves propagating in a horizontal path and experiencing anisotropic non-Kolmogorov turbulence. The anisotropic spectrum model is based on the assumption that circular symmetry is maintained in the orthogonal xy -plane throughout the path and that it includes the same degree of anisotropy along the direction of propagation for all the turbulence cell sizes. These expressions are developed in the weak fluctuation region using the Rytov approximation method and are independent of the knowledge of the temporal mutual coherence function for the optical waves. We perform our analysis based on a generalized von Karman power spectrum of the index of refraction. The spectrum considers the effect of finite inner and outer scales of turbulence, together with a non-Kolmogorov spectral power exponent α that varies between 3–4. The simulation results show that the anisotropic parameter impacts on the frequency spread by a factor . Moreover the frequency spread is most significant for α values around 3.1.

The expressions of wave structure function (WSF) and long-exposure modulation transfer function (MTF) for laser beam propagation through non-Kolmogorov turbulence were derived in our previous work. In this paper, based on anisotropic maritime atmospheric non-Kolmogorov spectrum, the new analytic expression of WSF for Gaussian-beam waves propagation through turbulent atmosphere in a horizontal path is derived. Moreover, using this newly derived expression, long-exposure MTF for Gaussian-beam waves is obtained for analyzing the degrading effects in an imaging system. Using the new expressions, WSF and MTF for Gaussian-beam waves propagating in terrestrial and maritime atmospheric turbulence are evaluated. The simulation results show that Gaussian-beam waves propagation through maritime turbulence obtain more degrading effects than terrestrial turbulence due to the humidity and temperature fluctuations. Additionally, the degrading effects under anisotropic turbulence get less loss than that of isotropic turbulence.