Near-Field Integrated Sensing and Communication with a Uniform Circular Array

Abstract

Near-field (NF) integrated sensing and communication (ISAC) is studied for a uniform circular array (UCA) and monostatic sensing. A continuous-time channel model is derived for the spherical wavefront and orthogonal frequency-division multiplexing. A multi-slot Cramèr-Rao lower bound (CRLB) for joint range-angle-Doppler estimation is derived under a slow-motion approximation, showing how the signal delay and wavefront curvature affect the range bound. A transmit beamformer that minimizes the position CRLB is designed via gradient descent, and a maximum-likelihood estimator is obtained by using the Levenberg-Marquardt algorithm initialized with a grid search. Simulations show that increasing the UCA radius improves angle and motion estimation at all distances, but improves the range bound only at distances far inside the Rayleigh distance, and lowers the reliable communication rate.

The paper has been submitted for IEEE Information Theory Workshop (ITW) 2027