Influence of On-Off Keying Duty Cycle on BER in Wireless Optical Communication Up to 75 Mbit/s Using an SPAD and a RC LED

In this paper we analyze the influence of the on-off keying duty cycle on the achievable bit error ratio (BER) in a optical wireless communication (OWC) system which employs a single photon avalanche diode (SPAD) based receiver and a red LED transmitter as a source. In a line of sight (LOS) channel configuration at a transmitting distance of 3 m the bit error rate (BER) improvement is demonstrated by varying the duty cycle of return to zero (RZ) line coding at 50 Mbit/s. Compared to NRZ line coding at the same transmitting distance and data rate the BER improvement is almost up to an order of magnitude lower when RZ coding is used. The reached BER values are below the limit for forward error correction (FEC) thus promising the increase of the maximum achievable transmission distance. Additionally, the BER improvement allowed the transmission below FEC limit over 3 m at an increased data rate of 75 Mbit/s.