Joint estimation of DOA and time-delay in underwater localization

Joint estimation of direction of arrival (DOA) and time-delay plays a great role in source localization, which attracts many researchers not only in the areas of radar, sonar, geological exploration but also in wireless communication. M. Wax (see IEEE Trans. on SP, vol.45, no.10, p.2477-84, 1997) applies approximate MLE with iteration algorithm, which convert a 2-D search into two or three 1-D search. A.J. van der Veen (see IEEE Trans. on SP, vol.46, no.2, p.405-18, 1998) use 2-D ESPRIT to conduct joint estimation. Both of them show good performance at a cost of large computation. Both of them require deconvolution in the frequency domain to transfer time-delay into phase. The deconvolution lends to two problems. One is blowing up noise, the other is leading to spurious peak if the emitted signal is non-minimum phase. In this paper, a simple method using 1-D ESPRIT is presented to complete joint estimation of DOA and time-delay, which requires no deconvolution. It is suitable for active underwater localization where a non-minimum phase signal is frequently employed. The method can estimate parameters of three reflectors with big difference between amplitudes as large as 12 dB. The statistical performance of new estimators and the probability of correct pairing are given by computer simulations. It shows that better performance of the new method can be achieved for multiple source localization even in low SNR.