A two phase hybrid RSS/AoA algorithm for indoor device localization using visible light

A two phase hybrid algorithm for estimating the location of a mobile node, which has the capability of measuring signal strength, azimuth, and elevation, in a smart space environment over the visible light channel is proposed. In contrast to conventional triangulation approaches which are performed in a simplified plane, the smart room architecture requires a non-planar solution due to the illumination requirement. Furthermore, conventional triangulation approaches can at times produce numerically ill-defined solutions, thereby prohibiting a notion of target location. Instead of solely relying on triangulation, the mobile node estimate their locations through a two phase approach in which they firstly exploit the signal strength observables with unique IDs to establish a coarse estimate, and secondly use the azimuth and elevation observables to establish a fine estimate. In many cases, the fine estimate will improve upon the coarse estimate; however when triangulation fails, the algorithm yield the coarse estimate rather than a localization failure. Since the environment model relies on the primary requirement of adequate illumination, the number of LED anchors and transmit power for communication functions are determined. Simulation results confirm the effectiveness of the hybrid two phase localization approach in a smart space indoor environment by having a median coarse phase accuracy of 34.88 cm and a fine phase median accuracy of 13.95 cm.