The Cramer-Rao bound (CRB) plays an important role in direction of arrival (DOA) estimation because it is always used as a benchmark for comparison of the different proposed estimation algorithms. In this correspondence, using well-known techniques of global analysis and differential geometry, four necessary conditions for the maximum of the log-likelihood function are derived, two of which seem to be new. The CRB is derived for the general class of sensor arrays composed of multiple arbitrary widely separated subarrays in a concise way via a coordinate free form of the Fisher Information. The result derived in [1] is confirmed.     «

The Cramer-Rao bound (CRB) plays an important role in direction of arrival (DOA) estimation because it is always used as a benchmark for comparison of the different proposed estimation algorithms. In this correspondence, using well-known techniques of global analysis and differential geometry, four necessary conditions for the maximum of the log-likelihood function are derived, two of which seem to be new. The CRB is derived for the general class of sensor arrays composed of multiple arbitrary w...     »