Multiple Exposure Coding for Short and Long Dual Transmission in Vehicle Optical Camera Communication

In vehicle optical camera communication (VOCC), LED lamps in a vehicle are used to transmit an optical signal that will be received by cameras attached in another vehicle. Although having many advantages, VOCC also has one drawback: in long-distance communication, transmitters are required to have low spatial frequencies to improve signal quality. However, for short-distance communication, the transmitters need to have high spatial frequencies to improve the data rate. To solve this problem, this paper proposes a multiple exposure-based overlay coding which allows both low and high spatial frequency signals to be transmitted in the same transmitter at the same time. Two cameras with exposure times set at different levels are used to receive the two kinds of signal. Consequently, the high signal quality of the long-distance communication and high data rate of the short-distance communication can be achieved simultaneously. The performance of the proposed coding is analyzed mathematically and then verified through simulations.