Transmit Beampattern Synthesis for Phased-MIMO Radar via a Unified Design Framework

Phased-multiple-input multiple-output (MIMO) radar provides greater degrees of freedom compared to phased array while requiring fewer arbitrary waveform generators than conventional MIMO radar, making it an effective solution for the trade-off beampattern performance and cost. In this work, we propose a method to synthesize transmit beampattern for phased-MIMO radar by jointly designing the transmit weight vectors and waveforms of its sub-arrays, with constant modulus constraints taken into account. First, we establish a unified beampattern design framework based on the weighted <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\ell _{p}}$</tex-math></inline-formula>-norm metric while introducing a scaling factor to enhance the control over mainlobe and sidelobe levels. This unified framework not only facilitates beampattern synthesis for phased-MIMO radar, but is also applicable to beampattern design for MIMO radar and phased array. Then, resorting to manifold optimization theory, we develop an iterative algorithm that transforms the resultant non-convex optimization problem into an unconstrained problem on a product Riemannian manifold space, which can be solved via parallel conjugate gradient algorithm, thereby achieving parallel optimization of transmit weight vectors, waveforms and the introduced scaling factor. Finally, we assess the performance of the proposed method in beampatterns design for phased-MIMO radar, phased array and MIMO radar via extensive numerical experiments.