Transmit Beampattern Synthesis for Active RIS-Aided MIMO Radar via Waveform and Beamforming Optimization

TL;DR

This paper proposes a joint waveform and ARIS reflection coefficient design for active RIS-aided MIMO radar to optimize beampatterns, reducing sidelobe levels and improving radar performance under practical waveform constraints.

Contribution

It introduces a novel optimization framework combining Dinkelbach transform, CADMM, and CCCP for beampattern synthesis in active RIS-assisted MIMO radar, addressing practical waveform constraints.

Findings

ARIS-aided MIMO radars outperform conventional radars in sidelobe suppression.

The proposed algorithms converge to global optimal solutions for subproblems.

Numerical results demonstrate significant sidelobe energy reduction with the new design.

Abstract

In conventional colocated multiple-input multiple-output (MIMO) radars, practical waveform constraints including peak-to-average power ratio, constant or bounded modulus lead to a significant performance reduction of transmit beampattern, especially when the element number is limited. This paper adopts an active reconfigurable intelligent surface (ARIS) to assist the transmit array and discusses the corresponding beampattern synthesis. We aim to minimize the integrated sidelobe-to-mainlobe ratio (ISMR) of beampattern by the codesign of waveform and ARIS reflection coefficients. The resultant problem is nonconvex constrained fractional programming whose objective function and plenty of constraints are variable-coupled. We first convert the fractional objective function into an integral form via Dinkelbach transform, and then alternately optimize the waveform and ARIS reflection coefficients. Three types of waveforms are unifiedly optimized by a consensus alternating direction method of multipliers (CADMM)-based algorithm wherein the global optimal solutions of all subproblems are obtained, while the ARIS reflection coefficients are updated by a concave-convex procedure (CCCP)-based algorithm. The convergence is also analyzed based on the properties of CADMM and CCCP. Numerical results show that ARIS-aided MIMO radars have superior performance than conventional ones due to significant reduction of sidelobe energy.