Movable waveguides improve antenna tracking and beamforming for users
Pinching-Antenna System With Movable Waveguides: Modeling and Optimization
Information Theory
Summary
Wireless communication systems need to send signals efficiently to many users in different places. The authors created a system where antenna parts can move on flexible cables to better point signals at users. For one user, they found the best positions for these parts to improve signal strength and designed a method to optimize their placement. For many users, they developed an efficient way to adjust positions to keep everyone’s connection good. Their tests show this moving system adapts well and performs better than fixed antenna setups.
What this means in practice
- •For wireless network engineers: Design antenna systems that adjust positions mechanically to better serve users locations and improve signal rates in 5G or future networks.
- •For satellite communication teams: Enhance adaptive beamforming by repositioning antennas to track ground users more effectively in multi-user scenarios.
Authors
Jingze Ding, Zijian Zhou, Bingli Jiao, Rui Zhang
Abstract
This paper proposes a movable waveguide (MW)-enabled pinching-antenna system (PASS), in which each waveguide is connected via a flexible cable and can be linearly moved by drivers. By simultaneously moving the MWs and the pinching antennas (PAs) on them, MW-enabled PASS can effectively track user locations and form flexible array geometries for efficient beamforming. We first examine the special case with a single user and derive the closed-form solutions for the optimal MW positions as well as an upper bound on the user rate. Furthermore, we develop a two-step optimization algorithm to maximize the achievable rate for the user, where the first step determines the optimal MW positions using the derived closed-form solutions, and the second step alternately optimizes the PA positions through a one-dimensional (1D) local search based on the user location. Then, for the general multi-user scenario, we derive the upper bounds on the minimum rate among all users. To maximize their minimum rate, we propose a low-complexity two-scale optimization algorithm, where the large-scale global search coarsely determines the MW and PA positions, followed by a small-scale local search to finely tune them. In addition, a two-timescale optimization scheme based on statistical channel information is investigated to reduce the mechanical movement overhead of the MWs. Simulation results demonstrate that the proposed scheme achieves performance close to the derived bounds. It also flexibly adapts to different user distributions compared with the conventional PASS employing dense or sparse fixed-position waveguides (FPWs), as well as fixed-position antenna (FPA) schemes.