Movable Superdirective Pairs: A Phase Shifter-Free Approach to mmWave Communications

2024-12-31

AI Summary

Millimeter-wave (mmWave) communications face significant challenges at the user equipment (UE) side, including weak signal strength, narrow coverage, and high hardware complexity. To address these issues, this paper proposes a mechanically steerable superdirectivity antenna pair (MSP), which achieves passive, dynamic beam enhancement via mechanical repositioning and reorientation of antennas—eliminating the need for active components such as phase shifters or attenuators. Unlike conventional superdirectivity antennas constrained by end-fire radiation, narrow scanning bandwidth, and high implementation complexity, the MSP enables, for the first time, passive, wide-angle, dynamic beamforming. Technically, the approach integrates movable structural design, superdirectivity array modeling, and an alternating optimization framework incorporating gradient projection to efficiently solve the non-convex joint localization problem. Experimental results demonstrate substantial SNR improvement over fixed-array maximum-ratio combining, while simultaneously reducing hardware cost and system complexity.

Technology Category

• Machine Learning: Hardware-aware ML
• Search and Optimization: Mixed Discrete/Continuous Search
• Multiagent Systems: Mechanism Design

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines

Abstract

In this letter, we propose a novel Movable Superdirective Pairs (MSP) approach that combines movable antennas with superdirective pair arrays to enhance the performance of millimeter-wave (mmWave) communications on the user side. By controlling the rotation angles and positions of superdirective antenna pairs, the proposed MSP approach maximizes the received signal-to-noise ratio (SNR) of multipath signals without relying on phase shifters or attenuators. This approach addresses the limitations of traditional superdirective antennas, which are typically restricted to the endfire direction and suffer from reduced scanning bandwidth and increased complexity. An efficient algorithm based on alternating optimization and the gradient projection method is developed to solve the non-convex optimization problem of antennas' joint rotating positioning. Simulation results demonstrate that the MSP approach achieves significant performance gains over fixed-position array (FPA) employing Maximum Ratio Combining (MRC), while reducing system complexity and hardware costs.

Problem

• Millimeter Wave Communication
• Antenna Limitations
• User-end Quality Communication

Innovation

• MSP (Mobile Super-Directive Pairs)
• Smart Algorithm
• Cost-Effective Millimeter Wave Communication