An Analysis of Phase Synchronization Mismatch Sensitivity for Coherent MIMO Radar Systems

TL;DR

This paper develops a hybrid Cramer-Rao bound to analyze how phase synchronization mismatches affect target localization accuracy in coherent MIMO radar systems with widely distributed antennas, providing insights for system design.

Contribution

It introduces a closed-form hybrid CRB for target localization considering phase mismatch, quantifies the mismatch effect, and links synchronization error levels to localization performance.

Findings

The mismatch effect depends on phase error variance and system geometry.

The derived bound separates the ideal and mismatch-induced localization errors.

The expression helps determine required synchronization levels for desired accuracy.

Abstract

In this study, the hybrid Cramer-Rao bound (CRB) is developed for target localization, to establish the sensitivity of the estimation mean-square error (MSE) to the level of phase synchronization mismatch in coherent Multiple-Input Multiple-Output (MIMO) radar systems with widely distributed antennas. The lower bound on the MSE is derived for the joint estimation of the vector of unknown parameters, consisting of the target location and the mismatch of the allegedly known system parameters, i.e., phase offsets at the radars. Synchronization errors are modeled as being random and Gaussian. A closed-form expression for the hybrid CRB is derived for the case of orthogonal waveforms.The bound on the target localization MSE is expressed as the sum of two terms - the first represents the CRB with no phase mismatch, and the second captures the mismatch effect. The latter is shown to depend on the phase error variance, the number of mismatched transmitting and receiving sensors and the system geometry. For a given phase synchronization error variance, this expression offers the means to analyze the achievable localization accuracy. Alternatively, for a predetermined localization MSE target value, the derived expression may be used to determine the necessary phase synchronization level in the distributed system.