Communication and Localization with Extremely Large Lens Antenna Array

TL;DR

This paper explores the use of extremely large lens antenna arrays (ExLens) for high-rate communication and accurate localization, leveraging their energy focusing properties to improve performance and reduce complexity in near-field and multi-user scenarios.

Contribution

It derives a closed-form array response for ExLens with spherical waves, revealing a window effect, and proposes an effective localization and channel estimation method close to the Cramér-Rao bound.

Findings

ExLens demonstrates significant spectral efficiency gains.

The proposed estimation method achieves near-optimal localization.

ExLens reduces system complexity compared to traditional arrays.

Abstract

Achieving high-rate communication with accurate localization and wireless environment sensing has emerged as an important trend of beyond-fifth and sixth generation cellular systems. Extension of the antenna array to an extremely large scale is a potential technology for achieving such goals. However, the super massive operating antennas significantly increases the computational complexity of the system. Motivated by the inherent advantages of lens antenna arrays in reducing system complexity, we consider communication and localization problems with an \uline{ex}tremely large \uline{lens} antenna array, which we call "ExLens". Since radiative near-field property emerges in the setting, we derive the closed-form array response of the lens antenna array with spherical wave, which includes the array response obtained on the basis of uniform plane wave as a special case. Our derivation result reveals a window effect for energy focusing property of ExLens, which indicates that ExLens has great potential in position sensing and multi-user communication. We also propose an effective method for location and channel parameters estimation, which is able to achieve the localization performance close to the Cram\'{e}r-Rao lower bound. Finally, we examine the multi-user communication performance of ExLens that serves coexisting near-field and far-field users. Numerical results demonstrate the effectiveness of the proposed channel estimation method and show that ExLens with a minimum mean square error receiver achieves significant spectral efficiency gains and complexity-and-cost reductions compared with a uniform linear array.