An in-Depth Survey of Visible Light Communication Based Positioning Systems <s> Terminology <s> Indoor positioning based on visible light communication (VLC) technology has become a very popular research topic ::: recently. This paper provides an overview of different VLC based indoor positioning techniques and their performance. ::: Three schemes of location estimation together with their mechanisms are introduced. We then present a detailed ::: comparison on their performances in terms of accuracy, space dimension and complexity. We further discuss a couple of ::: factors that would affect the performance of each of these positioning systems, including multipath reflections and ::: synchronization. Finally, conclusions and future prospects of research are addressed. <s> BIB001 </s> An in-Depth Survey of Visible Light Communication Based Positioning Systems <s> Terminology <s> While visible light communication (VLC) with inherent advantages is believed to be the next generation of wireless technology, positioning using visible light also has the potential of becoming a standard approach for positioning in the future. Although many indoor positioning systems based VLC have been proposed recently, there is very few paper related outdoor positioning using visible light. In this paper, firstly we point out difficulties when using visible light for outdoor positioning. Then we survey existing indoor positioning techniques using visible light and evaluate the potentialities and challenges of applying them to outdoor positioning. <s> BIB002
In the literature, the terminologies for VLC based positioning are quite confused. For example, while BIB001 and BIB002 used the term "VLC based positioning",  used a shorter and somehow friendlier term "visible light positioning" or "VLP",  even used the confusing term "optical wireless location" or "OWL" to refer to positioning systems based on VLC. Since the uniqueness of all positioning systems mentioned here comes from the use of VLC for determining the location, we suggest that the phrase "VLC based positioning" be used to distinguish the scheme from vision based positioning or infrared positioning.