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The Utilization of Artificial Neural Network Equalizer in Optical Camera Communications
Othman Isam Younus1, Navid Bani Hassan2, Zabih Ghassemlooy1
1Optical Communications Research Group, Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne NE1 8ST, UK.
Sensors (Basel, Switzerland)
|April 30, 2021
Summary
This study introduces an artificial neural network equalizer for optical camera communication systems using 4-level pulse amplitude modulation. The new equalizer significantly improves data transmission quality and achieves higher data rates with a single LED and commercial camera.
Area of Science:
- Optical Communications
- Artificial Intelligence
- Signal Processing
Background:
- Optical camera communication (OCC) systems face challenges in signal quality and transmission rates.
- Existing methods for evaluating OCC link quality lack standardization for comparing diverse image sensors.
- Constant power 4-level pulse amplitude modulation (4-PAM) is a potential modulation scheme for OCC.
Purpose of the Study:
- To propose and validate an artificial neural network (ANN)-based equalizer for 4-PAM OCC systems.
- To introduce a new metric, number of row pixels per symbol (Npps), for standardized comparison of OCC link quality.
- To experimentally demonstrate the effectiveness of the ANN equalizer in improving system performance.
Main Methods:
- Development and implementation of an ANN-based equalizer tailored for 4-PAM signals in OCC.
- Introduction and application of the Npps metric for evaluating communication link quality.
- Experimental setup using a single light-emitting diode (LED) and a commercial camera.
- Assessment of signal quality through eye-diagram opening, linearity, and bit error rate (BER).
Main Results:
- The equalized system achieved 30 pixels/symbol (Npps), compared to 20 Npps for the unequalized system.
- Demonstrated a non-flickering OCC system with equalization.
- Achieved transmission rates of up to 24.4 kbps (equalized) and 18.6 kbps (unequalized).
- Obtained an acceptable BER below the forward error correction limit.
- Reported a ~66% improvement in eye linearity with the proposed equalizer.
Conclusions:
- The ANN-based equalizer significantly enhances the performance of 4-PAM OCC systems.
- The Npps metric provides a fair and standardized method for comparing OCC systems with varying camera specifications.
- The proposed system demonstrates practical feasibility for reliable and high-quality optical wireless communication.
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