On the Utilization of Equivalent Sampling in Undersampled Asynchronous Camera Communication Protocols

With the increasing amount of LED lighting infrastructure present in our homes, offices, and vehicles, camera Communication (CamCom) protocols gained special interest in networking. Here the transmitters are the blinking LEDs, with blinking frequency high enough to not be visible for human eyes, and the receivers are commercial cameras with much lower sampling rate, thus undersampling necessarily happens. In applications, where the transmitted information is short and repeated periodically (e.g. beaconing in indoor localization systems), a natural way of message transmission is based on the equivalent sampling phenomenon. This paper investigates the effect of design parameters on the possible bitrate of the transmission in the practically important case when the transmitter and the receiver are unsynchronized and their clocks may drift. A design method will also be presented, which allows the optimal choice of parameters.