Multiple 3D far-field/near-field moving target localization using wideband echo chirp signals

In this paper, we propose a technique for active detection and estimation of the range, radial velocity and direction-of-arrival (DOA) of multiple moving targets in the three-dimensional space for both far-field and near-field cases using wideband chirp signals. The proposed technique is an extension of the method recently proposed by Leong in ['Multiple target localization using wideband echo chirp signals,' IEEE Trans. Signal Process., vol. 61, no. 16, pp. 4077-4089, Aug. 2013] for the localization of multiple far-field targets in the two-dimensional space. In our approach, the received signals at a sensor array are first decomposed into the spherical harmonic components and a modal preprocessing step is then carried out on the received wideband signals so that they can be further processed using narrowband techniques for parameter estimation. The application of fractional Fourier transform on the modal preprocessed signals allows the proposed method to identify closely spaced targets. This is demonstrated via computer simulations where the proposed technique achieved low root-mean-square errors in the parameters estimated in a scenario with closely spaced targets.