In this study, a reconfigurable intelligent surface (RIS)-assisted wireless-powered mobile edge computing (WP-MEC) system is proposed, where a single-antenna unmanned aerial vehicle (UAV)-mounted cloudlet provides offloading opportunities to K user equipments (UEs) with a single antenna, and the K UEs can harvest the energy from the broadcast radio-frequency signals of the UAV. In addition, rate-splitting multiple access is used to provide offloading opportunities to multiple UEs for effective power control and high spectral efficiency. The aim of this paper is to minimize the total energy consumption by jointly optimizing the resource allocation in terms of time, power, computing frequency, and task load, along with the UAV trajectory and RIS phase-shift matrix. Since coupling issues between optimization variable designs are caused, however, an alternating optimization-based algorithm is developed. The performance of the proposed algorithm is verified via simulations and compared with the benchmark schemes of partial optimizations of resource allocation, path planning, and RIS phase design. The proposed algorithm exhibits high performance in WP-MEC systems with insufficient resources, e.g., achieving up to 40% energy reduction for a UAV with eight elements of RIS.

The beamforming technique has attracted considerable attention in wireless communication due to its various advantages such as interference reduction and improved wireless resource efficiency. However, the beam alignment between transmitting and receiving devices, which is fundamentally required for the beamforming, poses a significant challenge due to the continuous variability of the wireless channel. Recently, a deep learning-based technique has been proposed to predict narrow beam indices by measuring wide beams. However, there is room for improvement in the performance of the neural network architecture employed in this technique. Therefore, we suggest a novel deep learning model architecture that incorporates a channel attention module for beam training. The simulation results show a significant enhancement in performance with our scheme compared to both a state-of-the-art approach and other existing methods across all scenarios. Particularly, we confirm that even when reducing the number of wide beams used for measurement by approximately $50\%$, our proposed approach achieves a performance close to that of the state-of-the-art scheme.

한국전자파학회논문지 (The Journal of Korean Institute of Electromagnetic Engineering and Science)

본 논문에서는 W-대역 탐색기용 새로운 이중편파 모노펄스 반사경 안테나의 설계를 제안한다. 4개의 정사각형 도파관으로 급전되는 새로운 이중편파 단일개구 다중모드 혼을 이용하여 모노펄스 패턴을 구현하였다. 기존의 단일개구 다중모드 혼은 단일편파에서만 동작한다. 제안된 혼의 치수변수를 반복적으로 조정하여 요구되는 합과 차패턴과 낮은 입력 반사계수를 얻었다. 설계된 피드는 다음의 합 및 차패턴 특성을 갖는다: 18.2㏈i의 합채널 이득, 22.3°에서 11.6㏈와 12.4㏈의 전계면 및 자계면 이득 테이퍼; 16.8㏈i의 차채널 이득, 22.3°에서 2.8㏈와 4.4㏈의 전계면 및 자계면 이득 테이퍼, 50㏈ 이상의의 영점깊이. 설계된 피드 혼을 50파장 카세그레인 반사경과 결합하여 고성능 W-대역 모노펄스 탐색기 안테나를 구현하였다. 설계된 탐색기 안테나는 42.2㏈i의 합패턴 이득, 1.41°의 빔폭, 1.61°의 교차각, 49.7㏈의 영점깊이, -16.8㏈의 부엽준위를 갖는다.