Fig. 1. Positioning 3D coordinates for devices in an indoor space using visible light.

Fig. 2. Typical room layout for a VLP system. The geometric angles between the receiver and transmitter are also noted.

Fig. 3. Taxonomy of positioning algorithms showing the main physical modalities, mathematical techniques, and extra peripherals.

Fig. 4. Example multiplexing schemes to prevent luminaire signal interference: a, TDM, b, FDM, c, SM, and d, WDM.

Fig. 5. Common benchmarks shown on a CDF: a, best accuracy, b, accuracy for 95% of cases, and c, accuracy for 100% of cases.

Fig. 6. Changing planes affects positioning accuracy as seen in these CDF curves.

Fig. 7. Receivers at positions a and b have the same FOV. However, the receiver at position b sees one less transmitter than the receiver at position a.

Fig. 8. In a typical 6m×6m space with four luminaires placed at positions 2 m away from each other, depending on the plane, a, 1 m away and b, 2 m away, the number of transmitters seen across the space changes.

Fig. 9. Signal strength fading with height. While the signal strength directly under the luminaire increases, the region of poor signal strength increases.

Fig. 10. Concept of ray–surface positioning showing angles of the steerable laser and Lambertian profile.

Fig. 11. MSE comparing ray–surface positioning to multilateration. Ray–surface provides 3D positioning and is significantly better than multilateration.