  Visible light communication (VLC) systems are promising candidates for future
indoor access and peer-to-peer networks. The performance of these systems,
however, is vulnerable to the line of sight (LOS) link blockage due to objects
inside the room. In this paper, we develop a probabilistic object detection
method that takes advantage of the blockage status of the LOS links between the
user devices and transceivers on the ceiling to locate those objects. The
target objects are modeled as cylinders with random radii. The location and
size of an object can be estimated by using a quadratic programming approach.
Simulation results show that the root-mean-squared error can be less than $1$
cm and $8$ cm for estimating the center and the radius of the object,
respectively.
