The Transmit Beampattern Design in MIMO Radar System: A Manifold Optimization based Method

Abstract

The beampattern design with constant modulus (CM) constraint is a key technical issue in Multiple-Input Multiple-Output (MIMO) radar system. The problem is non-convex, due to the CM constraint. Usually, the existing methods indirectly solve this problem by relaxing it to a more tractable form. These methods either degrade the performance or need huge computational cost. Different from the existing methods, a direct method is derived to solve the problem without relaxation. In the proposed method, the original problem is first converted to an Unconstrained Quadratic Optimization Problem (UQOP) over the non-convex complex circle manifold. Then, by efficiently deriving the descent direction and step size to ensure the cost function to be non-increasing, a novel Manifold Optimization-based Conjugate Gradient (MOCG) approach is derived to directly solve UQOP. Compared with current methods, the proposed method has following priorities: 1) The null is 25dB, and 30dB deeper than [11]–[12], respectively; 2) The Signal-to-Interference-and-Noise-Ratio (SINR) is 0.61dB, 3.68dB, and 0.47dB higher than [11]–[13], respectively.