Harnessing the Freedom of Non-Uniformity in Monostatic ISAC with Antenna Flexibility

2026-04-30

AI Summary

This work addresses the trade-off between communication rate and sensing performance in single-base integrated sensing and communication (ISAC) systems by proposing a geometry-aware non-uniform array design. The approach dynamically constructs a sparse, non-uniform effective array from the base station’s antenna pool through joint optimization of beamforming and antenna activation patterns. By leveraging weighted minimum mean square error minimization, continuous relaxation with penalty terms, and successive convex approximation, an efficient alternating optimization framework is developed that overcomes the conventional reliance on uniform arrays and large antenna counts. Experimental results demonstrate that, with fewer active antennas, the proposed scheme significantly outperforms uniform-array baselines and can even achieve comparable or superior communication sum rates and sensing accuracy using a reduced number of antennas.

Abstract

This paper studies flexible non-uniform array design for monostatic integrated sensing and communication (ISAC) systems. An antenna pool is considered at the base station, where each candidate antenna can be dynamically assigned to transmit, receive, or inactive modes, such that a non-uniform effective array is jointly constructed with the ISAC precoding design. We formulate a sum communication rate maximization problem by jointly optimizing the ISAC beamforming schemes and antenna-mode assignment under sensing, power, and antenna mode constraints. We develop an alternating-optimization-based solution framework mainly with the aid of weighted minimum mean square error, continuous relaxation-based penalty, and successive convex approximation. Numerical results show that the proposed non-uniform array achieves higher sum-rates than the uniform-array baselines, with particularly large gains when the number of activated antennas is small. Moreover, the proposed non-uniform array can achieve, and in some cases exceed, the performance of uniform array baselines with substantially fewer activated antennas, highlighting geometry-aware non-uniform array design as a compelling alternative to brute-force antenna scaling-based array design.

Problem

• non-uniform array
• integrated sensing and communication
• antenna flexibility
• monostatic ISAC
• sum-rate maximization

Innovation

• non-uniform array
• integrated sensing and communication (ISAC)
• antenna flexibility
• beamforming optimization
• geometry-aware design