Multisensor TDOA estimation in a multipath propagation environment using the EM algorithm

The expectation-maximization (EM) algorithm is presented as a means of performing passive, high-resolution, intersensor time difference of arrival (TDOA) estimation in the presence of correlated multipath interference and noise. The approach presented here assumes that the signal can be represented as a bandlimited complex Gaussian process, but is otherwise unknown. Within the EM algorithm, a conditional mean estimate of the transmitted signal spectrum is generated and used to determine the direct-path and multipath delays and complex amplitudes associated with each received signal. The delay/amplitude estimator takes the form of nonlinear least-squares optimization problem. The structure of the algorithm is described and its performance demonstrated through simulation.