CI-Based QoS-Constrained Transmit Signal Design for DFRC Systems with One-Bit DACs

In this paper, we investigate the transmit signal de-sign problem for a dual-functional radar-communication (DFRC) system equipped with one-bit digital-to-analog converters (DACs). Specifically, the one-bit DFRC waveform is designed to minimize the difference between the transmitted beampattern and a desired one, while ensuring constructive interference (CI)-based QoS constraints for communication users. The formulated problem is a discrete optimization problem with a nonconvex objective function and many linear constraints. To solve it, we first propose a penalty model to transform the discrete problem into a continuous one. Then, we propose an inexact augmented Lagrangian method (ALM) framework to solve the penalty model. In particular, the ALM subproblem at each iteration is solved by a custom-designed block successive upper-bound minimization (BSUM) algorithm, which admits closed-form updates and thus makes the proposed approach computationally efficient. Simulation results verify the superiority of the proposed approach over the existing ones in both the radar and communication performance.

I. Introduction

The dual-functional radar-communication (DFRC) system integrates radar and communication functionalities on one platform, attracting significant attention for its capability to save spectrum and hardware resources [1]–[4]. When employed with massive multiple-input multiple-output (MIMO) [5], the DFRC system can further attain enhanced radar and communication performance, as the increased number of antennas offers greater flexibility to mitigate the multiuser interference and shape the spectral beampattern for radar applications. However, a practical issue associated with massive MIMO technology is its high hardware cost and energy consumption. A promising way of addressing this challenge is to employ one-bit digital-to-analog converters (DACs) at each antenna element, which not only minimizes the hardware cost of DACs but also enables the use of the most energy efficient power amplifiers (PAs) [6].