Indoor 3-Dimensional Visible Light Positioning Based on Smartphone Camera: Error Metric and LED Layout Optimization

We consider 3-dimensional (3D) visible light positioning (VLP) based on smartphone camera in an indoor scenario. Based on the positioning model in the quantized pixel-domain, we characterize the 3D normalized positioning error metric (NPEM) through the partial derivative of the positioning function, and evaluate the NPEM for horizontal and non-horizontal receiver camera positions. Moreover, under horizontal receiver terminal position, we explore the relationship between the NPEM and the light-emitting diode (LED) cell layout, approximate the relationship between the NPEM and the number of LEDs captured by the camera, and evaluate the approximation accuracy according to the simulated positioning error. Based on the approximation results, we optimize the LED transmitter cell layout to minimize NPEM assuming structured square cell layouts with certain distance parameters.