Location Estimation via the Direction of Arrival Techniques Based on the IEEE 802.11n WLANs

Location estimation techniques have evolved recently and became an essential part in many applications. These techniques include received signal strength indication, finger printing, time of arrival, time difference of arrival, and direction of arrival. All the techniques, other than the last technique, are applicable through all the IEEE 802.11 standards. The direction of arrival can only be estimated via access points that implement the IEEE 802.11n, ac standard amendments that included Multiple Input Multiple Output antennas in its air interface. The required time synchronization and computational intensive triangulation for location estimation with the time-based methods are not needed if direction of arrival is used. In this paper, the WLAN standard IEEE 802.11n is tested for the maximum ranges of accurately estimated direction of arrival in indoor environments. The antenna inter-element spacing that maximizes this range is determined. The accuracy of angle estimation vs. signal to noise ratio is calculated. The wireless channel is modelled by the ray tracing model which enables determining all the information about incidence angles for different signals that reach the receive antenna elements. Different direction of arrival estimation algorithms are tested.