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

TL;DR

This paper introduces a phase shifter-free method using movable superdirective antenna pairs to improve mmWave communication performance by optimizing antenna positions and orientations, resulting in higher SNR and lower complexity.

Contribution

It presents a novel MSP approach that combines movable antennas with superdirective arrays, eliminating phase shifters and enhancing mmWave communication efficiency.

Findings

Achieves higher SNR compared to fixed arrays.

Reduces hardware complexity and costs.

Demonstrates significant performance improvements in simulations.

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.