Experimental Demonstration of Superimposed Data Transmission in Rolling Shutter Based Visible Light Communication

This study aims to provide adaptability to changes in the communication distance of rolling shutter based visible light communication (RS-VLC). A key issue in RS-VLC is the trade-off between the data rate and communication distance. To resolve this issue, we propose a superimposed data transmission method in which two sets of data, namely short- and long-range data, are superimposed and transmitted simultaneously. Short-range data are transmitted in long-bit sequences with a small number of iterations, whereas long-range data are transmitted in short-bit sequences with a large number of iterations. These two datasets can be separately decoded at the receiver by superimposing and transmitting them at different amplitudes. The proposed method can decode all the superimposed data at short ranges, thus suppressing data rate degradation. As the communication distance increases, the proposed method decodes only the available data, allowing for data reception over longer ranges, albeit at a lower data rate. We further extend the proposed method by adding a third set of data, namely mid-range data, for further flexibility in communication distance and data rate. The experimental results show that the proposed method achieves data reception over a longer distance (up to 150 cm) while suppressing throughput degradation at short-ranges, that is, it mitigates the trade-off between the data rate and communication distances compared to conventional $M$-ary pulse amplitude modulation systems.