Toward Dual-functional Radar-Communication Systems: Optimal Waveform Design

TLDR

We focus on a dual‑functional MIMO radar‑communication system in which a single transmitter simultaneously serves downlink cellular users and detects radar targets. The authors design optimal MIMO RadCom waveforms by minimizing downlink multi‑user interference, solving omnidirectional and directional beampattern problems with closed‑form globally optimal solutions, introducing a weighted optimization for radar‑communication trade‑offs with a low‑complexity algorithm, and proposing a branch‑and‑bound method for constant‑modulus waveforms that achieves global optimality and quantifies worst‑case complexity. The proposed designs incur computational costs comparable to conventional zero‑forcing precoding, and numerical results confirm the effectiveness of the optimal and branch‑and‑bound waveform approaches.

Abstract

We focus on a dual-functional multi-input-multi-output (MIMO) radar-communication (RadCom) system, where a single transmitter communicates with downlink cellular users and detects radar targets simultaneously. Several design criteria are considered for minimizing the downlink multi-user interference. First, we consider both the omnidirectional and directional beampattern design problems, where the closed-form globally optimal solutions are obtained. Based on these waveforms, we further consider a weighted optimization to enable a flexible trade-off between radar and communications performance and introduce a low-complexity algorithm. The computational costs of the above three designs are shown to be similar to the conventional zero-forcing (ZF) precoding. Moreover, to address the more practical constant modulus waveform design problem, we propose a branch-and-bound algorithm that obtains a globally optimal solution and derive its worst-case complexity as a function of the maximum iteration number. Finally, we assess the effectiveness of the proposed waveform design approaches by numerical results.