Adaptive dynamic thresholding method in optical communication systems and user devices.

Abstract

The invention proposes a method and system for adaptive dynamic threshold determination when receiving OOK signals in an optical communication system from LED to camera. The device uses an integrated IMU sensor to correct the camera tilt angle before determining the region of interest (ROI) containing the LEDs and an EWMA filter to update the threshold in real time. The system operates stably in varying lighting environments and even when the user holds the device in different positions. The processing procedure includes the following steps: Receiving images from the camera, identifying the ROI containing the LEDs via a synchronous prefix sequence (preamble). Measuring the average light intensity in the ROI region. Calculating the intermediate threshold and high / low thresholds. Correcting the ROI according to device movement using the IMU sensor, recalculating the new ROI position, and correcting the measured intensity to compensate for changes in received intensity. The system uses an EWMA filter to update the threshold in real time.If a tilt > 15° or a background light change > 20% is detected, the system automatically switches to adaptive threshold mode or local Otsu threshold mode. The binary result after thresholding is decoded to reconstruct the OOK bit sequence.

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