Multiple-path Direction-of-Arrival estimation for cognitive radio sensing

The estimation of the position of an emitting source is an important aspect of emerging cognitive radio systems. We readdress the known problem of estimating the Direction-of-Arrival (DOA) of an emitting source via passive radio means, namely an antenna array. The challenges in the considered scenarios are (a) time-varying, terrestrial multipath propagation with medium-to-low SNR and (b) very short capture records (single-packet processing). We present a two-stage estimation procedure: first an overall channel estimation stage followed by a DOA extraction method suitable to both blind (no training data employed) as well as training-assisted cases. The performance results presented demonstrate that the DOA estimation performance of this procedure is close to the theoretical Cramer-Rao Lower Bound for a large variety of challenging propagation scenarios.