  In this paper, we introduce a new uplink visible light indoor positioning
system that estimates the position of the users in the network-side of a
visible light communications (VLC) system. This technique takes advantage of
the diffuse components of the uplink channel impulse response for positioning,
which has been considered as a destructive noise in existing visible light
communication positioning literature. Exploiting the line of sight (LOS)
component, the most significant diffusive component of the channel (the second
power peak (SPP)), and the delay time between LOS and SPP, we present a proof
of concept analysis for positioning using fixed reference points, i.e. uplink
photodetectors (PDs). Simulation results show the root mean square (RMS)
positioning accuracy of 25 cm and 5 cm for one and 4 PDs scenarios,
respectively.
