Joint Range and Angle Estimation Using MIMO Radar With Frequency Diverse Array

TLDR

Phased array radar steers a fixed beam across all ranges, preventing range determination within a single pulse when range ambiguity exists. The study proposes an unambiguous joint range‑angle estimation method for MIMO radar employing a frequency‑diverse array. By applying a small frequency increment across array elements, the FDA‑MIMO transmit steering vector depends on both range and angle, and the authors derive Cramér‑Rao bounds and analyze the coupling between these parameters. The FDA‑MIMO system exploits range‑angle degrees of freedom to jointly estimate target range and angle, and numerical simulations confirm the approach’s effectiveness.

Abstract

Phased array is widely used in radar systems with its beam steering fixed in one direction for all ranges. Therefore, the range of a target cannot be determined within a single pulse when range ambiguity exists. In this paper, an unambiguous approach for joint range and angle estimation is devised for multiple-input multiple-output (MIMO) radar with frequency diverse array (FDA). Unlike the traditional phased array, FDA is capable of employing a small frequency increment across the array elements. Because of the frequency increment, the transmit steering vector of the FDA-MIMO radar is a function of both range and angle. As a result, the FDA-MIMO radar is able to utilize degrees-of-freedom in the range-angle domains to jointly determine the range and angle parameters of the target. In addition, the Cramér-Rao bounds for range and angle are derived, and the coupling between these two parameters is analyzed. Numerical results are presented to validate the effectiveness of the proposed approach.