Smartphone Image Receiver Architecture for Optical Camera Communication

As an extension of visible light communications (VLC), optical camera communications (OCC) are poised to play an important role in the success of VLC technology. Comparing with VLC systems based on photodiodes, OCC systems have a number of advantages in terms of hardware, communications channels, and business trends. However, these systems also have several disadvantages, such as limitations on the data rate, the need for synchronization between the transmitter and receiver, and inter-channel interference. These issues are a result of limitations in the camera sampling rates, frame rate variations, and motion stabilization. To address these limitations, we propose a new image sensor architecture for smartphone-based OCC that incorporates three primary functions: motion stabilization, frame rate control, and auto-exposure control. First, the motion stabilization function combines image sensor data and gyroscope motion information in order to select accurate pixel data. Second, the frame rate control function increases the frame rate using an over-scan scheme and contributes to the data throughput and motion compensation in the time domain. Finally, we control both the auto-exposure and focus functions in order to avoid blurring effects and variations in the frame rate. Experiments show that the proposed receiver architecture with adaptive frame rates and motion stabilization holds great promise for OCC.