Azimuth and Position Tracking in Wireless Local Area Networks

Signal strength measurements in a wireless local area network (WLAN) can be used for indoor positioning in guidance systems. To improve accuracy and robustness directional fingerprinting is researched. It makes use of directional antennas and enables simultaneous azimuth and position estimation. To achieve suitable estimation results, two methods are developed and analyzed: using receiver antenna diversity and using tracking algorithms.

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The aim of this work is to analyze the effects of directional antennas on signal strength measurements in wireless networks and to use the findings for position and azimuth estimation. This could improve guidance systems for smartphones in indoor environments, particularly accuracy and robustness. A common localization method is fingerprinting by correlating signal strength measurements with reference values from a database. To understand the role of the orientation of the measurement devices better the effects of directional antennas on the signal strength measurements are studied using simulations and measured data. Of particular interest, here is multipath propagation of signals. Based on this knowledge, directional fingerprinting is developed and discussed. It is based on signal strength measurements of directional antennas to enable simultaneous estimation of azimuth and position. The quality of the reference values in the database is crucial especially for directional fingerprinting. To achieve suitable estimation results, two methods are developed and analyzed: using receiver antenna diversity and using tracking algorithms together with directional fingerprinting.