Equalization of camera-based channel to mitigate uncertain sampling for optical camera communications

The asynchronous nature of optical camera communication makes uncertain sampling a fundamental and inevitable problem that degrades data transmission performance. Based on a parametric model describing the exposure effect of the camera-based channel as the source of uncertain sampling, a simple channel equalization method and implementation are proposed in this paper to mitigate the uncertain sampling by exploiting the space-time relationship of the transmitted spatial delayed pulse width modulation waveform on multiple light sources. In addition, the rate of equalization error caused by under-sampling and over-exposure is analyzed for different duty cycles and exposure times. Numerical simulation and experiment results demonstrate the availability and reliability in mitigating uncertain sampling by the proposed channel equalization.