Target localization accuracy and multiple target localization: Tradeoff in MIMO radars

This paper undertakes the study of localization performance of multiple targets in coherent MIMO radar systems with widely spread elements. MIMO radar systems with coherent processing and a single target were shown to benefit from a coherency and spatial advantages. The first is proportional to the ratio of the signal carrier frequency to the effective bandwidth, while the latter provides a gain proportional to the product of the number of transmitting and receiving sensors. In the current study, the model in extended to the estimation accuracy of multiple targets. The Cramer-Rao lower bound (CRLB) for the multiple targets localization problem is derived and analyzed. The localization is shown to benefit from coherency advantage. The tradeoff between target localization accuracy and the number of targets that can be localized is shown to be incorporated in the spatial advantage term. An increase in the number of targets to be localized exposes the system to increased mutual interferences. This tradeoff depends on the geometric footprint of both the sensors and the targets, and the relative positions of the two. Numerical analysis of some special cases offers an insight to the mutual relation between a given deployment of radars and targets and the spatial advantage it presents.