ABSTRACT
This chapter discusses received signal strength (RSS)-based positioning algorithms, which includes a wide variety of algorithms used in numerous applications. Short-range positioning applications use the RSS directly because the ratio of the coverage of the reference point to the required precision is low. The chapter describes RSS-based localization algorithms using outdoor fingerprinting. The maximum likelihood grid triangulation is a grid-based computational algorithm that extends the idea of rim shape certainty region to triangulation of a target tag using multiple reference points. Both Real-Time Location Services and Wireless Positioning Systems (WPS) systems are opportunistic Wi-Fi localization systems using pattern recognition algorithms. WPS systems generally use the simple centroid algorithms to map the database of RSS fingerprints to a database of access points (AP) locations, and they assign a quality of estimate parameter to each AP location in the database. To localize a device using its RSS reading from different APs, they use the weighted centroid algorithm and the AP location database.
