On the distribution of ambiguity levels in MIMO radar

The statistical behavior of sidelobe-ambiguity arising in location estimation in distributed coherent MIMO radar is studied in this paper. A model is developed for analyzing the statistics of the localization metric under random sensor locations. Closed form expressions are obtained for the mean and variance of the localization metric. It is shown that the mean is independent of the number of sensors and its sidelobes decrease with the squared distance from the coherence point of the MIMO array. With M transmit sensors and N receive sensors, the variance behaves as 1/MN for locations beyond the vicinity of the target being observed. When all N sensors function as transceivers, the variance approaches 2/N². Except in the vicinity of the target, the side lobe levels have equal distribution at every location. The study is extended to derive the statistics of the peak sidelobe level and a simple expression is obtained relating the required number of sensors for a tolerated level of peak sidelobes and a desired confidence level.