  Mutual relative localization and identification is an important feature for
the stabilization and navigation of multi-Unmanned Aerial Vehicle (UAV)
systems. Camera-based communications technology, also referred to as Optical
Camera Communications (OCC) in the literature, is a novel approach that could
bring a valuable solution to such a complex task. In such system, the UAVs are
equipped with LEDs that act as beacons and with cameras allowing them to locate
the LEDs of other UAVs. Specific blinking sequences are assigned to the LEDs of
each of the UAVs in order to uniquely identify them. This camera-based relative
localization and identification system is immune to Radio Frequency (RF)
electromagnetic interference and operates in Global Navigation satellite (GNSS)
denied environments. In addition, since many UAVs are already equipped with
cameras, the implementation of this system is inexpensive. In this article, we
study in detail the capacity of this system and its limitations. Furthermore,
we show how to construct blinking sequences for UAV LEDs in order to improve
system performance. Finally, experimental results are presented to corroborate
the analytical derivations.
