Near-Field Multi-Cell ISCAP with Extremely Large-Scale Antenna Array

TL;DR

This paper explores a multi-cell near-field system using extremely large-scale antenna arrays to simultaneously support sensing, communication, and wireless power transfer, addressing complex design challenges with robust optimization and practical schemes.

Contribution

It introduces a novel robust beamforming optimization framework for near-field multi-cell ISCAP systems with ELAA, including a convex relaxation approach and a low-complexity MRT scheme.

Findings

Trade-offs among sensing, communication, and WPT are characterized.

The proposed methods achieve near-optimal detection and energy transfer performance.

The asymptotic MRT scheme simplifies implementation with large antenna arrays.

Abstract

This paper investigates a coordinated multi-cell integrated sensing, communication, and powering (ISCAP) system operating in the electromagnetic near field, where each base station (BS) employs an extremely large-scale antenna array (ELAA) to simultaneously support downlink communication, wireless power transfer (WPT), and environmental sensing. Three categories of communication users (CUs) with different interference cancellation capabilities are considered, and sensing is enabled through a distributed multiple-input multiple-output (MIMO) radar architecture. To address the resulting design challenges, a robust optimization framework is proposed by optimizing the beamforming strategy to maximize the worst-case detection probability over a prescribed sensing region, subject to per-user signal-to-interference-plus-noise ratio (SINR) constraints and energy harvesting requirements at energy receivers (ERs), while explicitly capturing the uncertainty in ER locations. By leveraging semidefinite relaxation (SDR), the original non-convex problem is reformulated as a convex semidefinite program with a provably tight relaxation. Furthermore, a low-complexity maximum ratio transmission (MRT)-based suboptimal scheme is developed, yielding a closed-form solution in the asymptotic regime as the number of antenna elements approaches infinity. Extensive numerical results reveal the fundamental trade-offs among sensing accuracy, communication reliability, and WPT efficiency.