Telecom

As part of non-terrestrial networks (NTN), the Low Earth Orbit (LEO) plays a critical role in supporting high-throughput wireless communication. However, the high-speed mobility of LEO satellites, coupled with the high density of user terminals, makes efficient user assignment crucial in maintaining overall wireless performance. The suboptimal assignment from LEO satellites to user terminals can result in frequent unnecessary handovers, rendering the user terminal unable to receive the entire downlink signal. Consequently, it reduces user rate and user satisfaction metrics. However, finding the optimum user assignment to reduce handover issues is categorized as a non-linear programming problem with a combinatorial number of possible solutions, resulting in excessive computational complexity. Therefore, this study proposes a distributed user assignment for the LEO networks. By utilizing message-passing frameworks that map the optimization problem into a graphical representation, the proposed algorithm splits the optimization problem into a local mapping issue, thereby significantly reducing computational complexity. By exchanging small messages iteratively, the proposed algorithm autonomously determines the near-optimal solution. The extensive simulation results demonstrate that the proposed algorithm significantly outperforms the conventional algorithm in terms of user rate and user satisfaction metric under various wireless parameters.

Scalar multiplication is the basis of the widespread elliptic curve public key cryptography. Standard scalar multiplication is vulnerable to side-channel attacks that are able to infer the secret bit values by observing the power or delay traces. This work utilizes the arithmetic properties of scalar multiplication to propose two scalar multiplication algorithms to insulate ECC implementations from side-channel attacks. The two proposed designs rely on randomly permuting the ordering and storage locations of the different scalar multiplication values $2^{i}G$ as well as the corresponding secret key bits $k_i$. Statistical analysis and Python 3.9.13implementations confirm the validity of the two algorithms. Numerical results confirm that both designs produce the same results as the standard right-to-left scalar multiplication algorithm. Welch’s t-test as well as numerical simulations confirm the immunity of our proposed protocols to side-channel attacks.

Dielectric covers are generally used to provide external protection to antenna systems by providing electromagnetic transparency. They are utilized in ground applications as well as for protecting airborne, Sat Com, terrestrial and underwater antenna installations. This paper presents a unique and universal design of dielectric sandwich-layered cover that can effectively protect antennas operating in a large frequency band from 1 GHz to 28 GHz, including millimeter-wave and microwave ranges, with minimum insertion loss for various incident angles. The proposed single dielectric cover may give sufficient protection for an entire tower or chimney housing multiple antennas, ranging from first-generation to fifth-generation microwave base-station antennas, as well as other wireless/broadcast antennas in millimeter or lower frequency ranges. In the first step, optimum dielectric constant and thickness of the dielectric cover are calculated numerically through a MATLAB (R2015a) code. In the second step, a floquet port analysis is performed to observe the insertion loss through the transmission coefficient against various frequency band-spectrums in microwave and millimeter-wave ranges for validation of the proposed synthesis. The ANSYS 18.2 HFSS tool is used for the purpose. In the third step, fabrication of the dielectric-layered structure is completed with the optimum design parameters. In the final step, the dielectric package is tested under various fabricated antennas in different frequency ranges.