Unimodular Waveform Design for Dual-Function Radar-Communication Systems Under Per-User MUI Energy Constraint

In this letter, we investigate the per-user MUI energy-controllable waveform design problem in Dual-Function Radar-Communication (DFRC) systems. Due to the unimodular constraint and per-user MUI energy constraint, the problem is non-convex and difficult to solve. To address it, the Inequality Constrained Manifold Optimization (ICMO) method is proposed. First, we transform the per-user MUI energy constraint into a penalty function added to the objective function through the exact penalty technique, resulting in a transformed problem containing only the unimodular constraint. Then, we note that the Complex Circle Manifold (CCM) naturally satisfies the unimodular constraint, the problem can be further converted into an unconstrained problem over CCM, and we derive a conjugate gradient descent (CGD) algorithm to solve it. Compared with existing methods, the proposed method exhibits advantages in terms of per-user communication performance, signal-to-interference-and-noise ratio (SINR), and beampattern performance. Besides, our method has lower computational costs.