Noncoherent dimming frequency shift On-Off keying scheme for low data rate optical street lighting communication

Dimming support and the avoidance of flickering effects are key challenges for visible light communication (VLC). Dimming frequency shift On-Off keying (DFSOOK) is based on frequency shift keying (FSK) and can be used for noncoherent detection. FSK needs clock detection but no synchronization between transmitter and receiver. This is necessary for optical camera communications using image sensors to receive LED modulated data and to detect objects simultaneously. In this paper a practical approach is elaborated with typical parameters to proof the usage of DFSOOK for VLC. A DFSOOK scheme, proposed for a street lighting system, is elaborated and tested. A new finding of this investigation is the combination of pulse width modulation (PWM) for dimming support and FSK for data transmission according to different dimming conditions. The bit error rate (BER) at different received dimming levels is measured for DFSOOK. As a result the practical transceiver realization requires more effort for a low BER at low duty cycles and longer transmission reach for optical street lighting communication.