Harnessing the Freedom of Non-Uniformity in Monostatic ISAC with Antenna Flexibility
For ISAC system designers, this work offers a geometry-aware alternative to brute-force antenna scaling, enabling performance gains with reduced hardware complexity.
This paper proposes a flexible non-uniform array design for monostatic ISAC systems, jointly optimizing beamforming and antenna-mode assignment. The proposed method achieves higher sum-rates than uniform arrays, especially with few antennas, and can match or exceed uniform array performance with fewer activated antennas.
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.