DC bias optimization in intelligent DCO-OFDM Li-Fi systems using hybrid machine learning with hardware validation

The main goal of this paper is to determine the optimal DC bias value for DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM)- based Light fidelity (Li-Fi) systems using machine learning (ML) algorithms. The reason for this is that in DCO-OFDM, applying either a significant or a slight DC bias can lead to inefficiencies, such as increased clipping noise or reduced optical power. Therefore, it is crucial to determine the most appropriate DC bias level. So, to achieve this, ML algorithms were implemented. This paper compares ML techniques, including hybrid linear regression with K-Nearest Neighbors (KNN) and hybrid polynomial regression with KNN, for predicting the ideal DC bias value in DCO-OFDM-based Li-Fi systems. The models were evaluated based on their Root Mean Square Error (RMSE), the Coefficient of Determination (R2), and the Mean Absolute Percentage Error (MAPE). The results show that hybrid polynomial regression with KNN outperforms the other models, achieving a lower RMSE of 0.18847, a higher R2 of 96.908%, and a lower MAPE of 9.271%. In addition, to validate the model's performance using real-world measurements, a hardware implementation of the Li-Fi system was developed using an Arduino-based receiver to collect actual signal data, which was then used to further evaluate prediction accuracy. The hardware results further confirmed the superiority of the hybrid polynomial regression with KNN model, achieving an RMSE of 0.296 and an R² score of 81.37%, consistent with the simulation outcomes and demonstrating its robustness in real-time scenarios. These findings suggest that hybrid polynomial regression with KNN can be an effective technique for predicting the optimal DC bias value in DCO-OFDM-based Li-Fi systems.