Fast Joint Estimation of Time of Arrival and Angle of Arrival in Complex Multipath Environment Using OFDM

Joint time of arrival (TOA) and angle of arrival (AOA) estimation based on a uniform circle array (UCA) involves problems, including high computational complexity in the multi-dimensional spectral search method and lack of applicability in coherent multipath environments. In this paper, we introduce a fast estimation algorithm based on the orthogonal frequency-division multiplexing system that uses space- frequency characteristics to reconstruct the virtual array and extend the array aperture. First, we combine the array structure with the signal frequency features to construct the extended virtual array. We then calculate the channel frequency response covariance matrix via frequency-domain smoothing preprocessing and determine a closed-form solution of AOA using UCA estimating signal parameters via rotational invariance techniques. Finally, using the estimated angle values, we perform a 1-D spectral search to determine the TOA values. The simulation results indicate that the proposed method provides an accurate estimation under the low signal-to-noise ratio conditions in coherent, independent, or mixed multipath environments, and provides a better performance than the multi-dimensional spectral peak search method, in terms of both computational complexity and estimation accuracy.