Efficient Transmit Beamspace Design for Search-free Based DOA Estimation in MIMO Radar

TL;DR

This paper introduces a novel transmit beamspace design method for MIMO radar that enables search-free DOA estimation by shaping the transmit beampattern and establishing rotational invariance, improving estimation accuracy.

Contribution

The paper proposes a new transmit beamspace design approach that allows search-free DOA estimation in MIMO radar, using convex optimization and spatial division techniques.

Findings

Enhanced DOA estimation accuracy with the proposed design.

Effective beamspace shaping for arbitrary beampatterns.

Improved performance over traditional MIMO radar methods.

Abstract

In this paper, we address the problem of transmit beamspace design for multiple-input multiple-output (MIMO) radar with colocated antennas in application to direction-of-arrival (DOA) estimation. A new method for designing the transmit beamspace matrix that enables the use of search-free DOA estimation techniques at the receiver is introduced. The essence of the proposed method is to design the transmit beamspace matrix based on minimizing the difference between a desired transmit beampattern and the actual one under the constraint of uniform power distribution across the transmit array elements. The desired transmit beampattern can be of arbitrary shape and is allowed to consist of one or more spatial sectors. The number of transmit waveforms is even but otherwise arbitrary. To allow for simple search-free DOA estimation algorithms at the receive array, the rotational invariance property is established at the transmit array by imposing a specific structure on the beamspace matrix. Semi-definite relaxation is used to transform the proposed formulation into a convex problem that can be solved efficiently. We also propose a spatial-division based design (SDD) by dividing the spatial domain into several subsectors and assigning a subset of the transmit beams to each subsector. The transmit beams associated with each subsector are designed separately. Simulation results demonstrate the improvement in the DOA estimation performance offered by using the proposed joint and SDD transmit beamspace design methods as compared to the traditional MIMO radar technique.