Beacon placement for range-based indoor localization

In this paper, we address the problem of range-based beacon placement given a floor plan to support indoor localization systems. Existing approaches for trilateration require three or more beacons to determine a unique position solution. We show that with prior knowledge of the map and a model of beacon coverage, it is possible to uniquely localize with only two beacons. This not only reduces installation cost by requiring fewer nodes, but can also improve robustness. One of the main challenges with respect to beacon placement algorithms is defining a metric for estimating performance. We propose augmenting the commonly used Geometric Dilution of Precision (GDOP) metric to account for indoor spaces. We then use this enhanced GDOP metric as part of a toolchain to compare various beacon placement algorithms in terms of coverage and expected accuracy. When applied to a set of real floor plans, our approach is able to reduce the number of beacons between 22% and 60% (33% on an average) as compared to standard trilateration.