Angle Diversity to Increase Coverage and Position Accuracy in 3D Visible Light Positioning

The most common approach to light-based indoor positioning relies on multilateration of received signals to the mobile device. Any deficiencies in the fidelity of these light signals can significantly distort position estimates. In this paper, we propose a method to dynamically control the light distribution from the overhead luminaires to mitigate fading effects that would otherwise occur under static lighting. By manipulating the direction of the luminaire, effectively the dispersion pattern, we introduce signal diversity in the form of multiple pointing angles and light distributions. In addition to providing angle diversity, steering and then tracking sustains the maximal line-of-sight path between a source and receiver, which reduces angle-dependent attenuation and optimizes the signal-to-noise ratio for any coordinate without needing to change the physical properties of the source or receiver. This gain in signal strength combats the limited field-of-view of luminaires and photodiodes to provide better overall coverage, which translates directly to increase positioning accuracy, particularly in a 3D space. In the results, we show field-of-view gains of 43% and improvements in MSE of 20cm.