Compared to the conventional two-step (including direction finding and position estimation) localization mechanism

the direct position determination (DPD) approach presented by Weiss and Amar has lower estimation errors and stronger resolution capability.Moreover

this technique provides a more convenient way to incorporate the signal waveform information.In this paper

the theoretical performance of the DPD algorithm presented by Weiss and Amar (called Weiss-Amar algorithm) is studied analytically.The asymptotical consistency is proved and the closed-form expression of the estimation variance is derived based on the error perturbation analysis method.It is also noted that the localization accuracy of this algorithm will decrease if the signals are correlated with each other.In order to solve this problem

an improved DPD algorithm is proposed for the case of known waveforms.In the new algorithm

the position parameters of all targets are considered as a whole to be estimated by using the alternating projection iteration.The performance improvement compared to the Weiss-Amar algorithm is remarkable for correlated signals.Furthermore

the Cramr-Rao bound (CRB) on the direct position estimation in presence of known waveforms is also deduced.Simulation results corroborate the effectiveness of the theoretical analysis and the advantage of the proposed algorithm.