Tracking of Moving Targets with MIMO Radar

A linear array radar can be operated as a multiple-input multiple-output (MIMO) radar or a directed beam radar. A MIMO radar transmits orthogonal waveforms on each array element, which can achieve virtual aperture extension. Compared to a directed beam radar, MIMO radar requires longer integration times to maintain the same energy on target. This results in narrower Doppler bins but increased range-Doppler migration, which decreases probability of detection. This paper compares the tracking performance of MIMO and Directed Beam radar. The comparison explicitly quantifies differences in beamwidth, Doppler bin width, and probability of detection due to range-Doppler migration. Full and partial velocity and acceleration compensation is considered. Single-target track completeness and track accuracy are compared for directed beam radar, MIMO radar with full compensation, MIMO radar with partial compensation, and uncompensated MIMO radar. It is shown that compensation is required to prevent degraded probability of detection and track completeness as target velocity and acceleration increase. 1.0 INTRODUCTION A linear array radar is traditionally operated as a phased array radar, also known as a directed beam radar, where each array element transmits an identical waveform with perhaps a phase shift to steer the beam. There is now increasing interest in operating a linear array as a multiple-input multiple-output (MIMO) radar, where distinct elements or subarrays transmit different waveforms. If the waveforms are orthogonal, then their returns can be separated from each other at the radar receiver. Previous work has considered omnidirectional search modes and transmit beamsteering on receive [1], [2]. Rabideau [3] conducted a tradeoff analysis for MIMO radar and directed beam radar by minimizing an objective function that describes the relationship between performance and cost. Target tracking resolution for MIMO radar was described with respect to ambiguity functions in [4]. Multiple target tracking for MIMO radar was considered in [5], where target localization performance was analyzed. In this paper the tracking performance of directed beam radar and MIMO radar are compared by explicitly quantifying beamwidth, Doppler bin width, and range-Doppler migration for both modes. This paper is organized as follows. Section 2.0 specifies relevant results that enable the tracking comparison. Section 3.0 proposes full and partial compensation schemes to mitigate range-Doppler migration. In Section 4.0 the tracking performance of directed beam and MIMO radar modes are compared. Finally, conclusions are presented in Section 5.0. 2.0 PRELIMINARIES The radar is a linear antenna array with M transmit/receive elements and is operated in one of two modes. In Directed Beam mode, each element transmits the same waveform with a phase shift to STO-MP-SET-241 4-2 1 PUBLIC RELEASE