Access Point topology evaluation and optimization based on Cramér-Rao Lower Bound for WLAN indoor positioning

Abstract

WLAN Access Point network is typically optimized for communication scope, and not for localization. It is thus important to understand the positioning accuracy limits under a certain given Access Point topology and to be able to make design recommendations if the Access Point topology can be adapted better for the navigation needs. This paper calculates a Cramér-Rao Lower Bound -based criterion for Received Signal Strength -based positioning. Two study cases are presented about how the proposed criterion can be used to choose the optimal Access Point density and the optimal Access Point topology in a network designed for positioning purposes. In addition, our Cramér-Rao Lower Bound-based criterion can also be used to estimate the expected accuracy bound in an existing network, based on its underlying Access Point density or topology. Measurement-based results are used to verify our proposed approach.