Application of beamforming in wireless location estimation

Abstract

A simple technique to estimate the position of a given mobilesource inside a building is based on the received signal strength. For this methodology to have a reasonable accuracy, radiovisibility of the mobile by at least three access points isrequired. To reduce the number of the required access points andtherefore simplify the underlying coverage design problem, wepropose a novel scheme that takes into account the distribution ofRF energy around the receiver. In other words, we assume that thereceiver is equipped with a circular array antenna withbeamforming capability. In this way, the spatial spectrum of thereceived power can be measured by electronically rotating the mainlobe around the 360-degree field of view. This spatial spectrumcan be used by a single receiver as a means for estimating theposition of the mobile transmitter. In this paper, we investigatethe feasibility of this methodology, and show the improvementachieved in the positioning accuracy.