Phase Synchronization for Coherent MIMO Radar: Algorithms and Their Analysis

Multiple-input multiple-output (MIMO) radar can achieve improved localization performance by employing a coherent processing approach with proper antenna positioning. Coherent processing, however, entails the challenge of ensuring phase coherence of the carrier signals from different distributed radar elements. In this work, we aim to address such a challenge by providing a systematic treatment of the phase synchronization problem in coherent MIMO radar systems. We propose and study three different approaches for reaching a common notion of phase in coherent MIMO radar, namely, the master-slave closed-loop algorithm, the round-trip algorithm and the broadcast consensus based algorithm. These algorithms range from centralized to distributed types, and include both noniterative and iterative approaches. They do not require a priori establishment of the time synchronization, and thus are all time asynchronous in nature. Under a similar analytical framework, we mathematically characterize each of these algorithms, and further derive and study the statistical properties of a few relevant figures of merit including the resulting phase synchronization error. Simulation results are presented to validate our theoretical analysis.