Joint Antenna Rotation and IRS Beamforming for Multi-User Uplink Communications
🤖 AI Summary
This work addresses the performance degradation of base station antennas caused by physical blockages and the angular mismatch arising when intelligent reflecting surfaces (IRSs) are deployed in antenna sidelobe regions. To overcome these challenges, the paper proposes a novel co-design framework that integrates a rotatable base station antenna with an IRS, jointly optimizing the three-dimensional antenna orientation, receive beamforming, and IRS phase shifts to maximize the sum rate of a multiuser uplink system. An efficient alternating optimization algorithm is developed, combining projected gradient ascent, closed-form beamforming solutions, and fractional programming techniques to tackle the resulting non-convex problem. Simulation results demonstrate that, under large angular mismatch conditions, the proposed scheme significantly outperforms fixed-antenna systems in terms of sum rate, thereby enhancing wireless coverage and communication quality.
Application Category
📝 Abstract
Rotatable antenna (RA) enhances wireless coverage through directional gain steering, yet suffers from performance degradation under physical blockages. Intelligent reflecting surface (IRS) establishes reflective paths to bypass obstacles, but suffers from angular mismatch when deployed in the side-lobe region of base station (BS) antennas. To address this issue, we propose a new RA-enabled IRS-assisted multi-user uplink system, in which the BS antennas are capable of flexibly adjusting their 3D orientations to align their boresights with the IRS. We formulate a sum rate maximization problem by jointly optimizing the antenna 3D rotations, receive beamforming and IRS phase shifts. To tackle this non-convex problem, we propose an efficient alternating optimization (AO) algorithm. Specifically, we iteratively update the antenna rotations via projected gradient ascent (PGA), compute the receive beamforming via a closed-form solution, and optimize the IRS phase shifts via fractional programming (FP). Numerical results demonstrate that the proposed system yields significant performance gains over conventional fixed-antenna systems, especially under large angular misalignments.
Problem
Research questions and friction points this paper is trying to address.
rotatable antenna
intelligent reflecting surface
angular mismatch
multi-user uplink
physical blockage
Innovation
Methods, ideas, or system contributions that make the work stand out.
Rotatable Antenna
Intelligent Reflecting Surface
3D Antenna Rotation
Alternating Optimization
Uplink Multi-User Communication
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