# The Utilization of Artificial Neural Network Equalizer in Optical Camera Communications +
## 1 Introduction
Whereas a 16 \(\times\) 16 array \(\mu\)LED and a high-speed camera with \(R_{f}\) of 960 fps and using \(R_{b}\) of 122.88 kb/s was reported in [23]. In OCC systems, equalization methods can also be deployed to compensate for spatial and temporal induced dispersion. In [24], an OOK VLC (a single LED) and camera-based Rx with a dual equalization scheme to compensate for both spatial and temporal dispersion were reported with increased \(R_{b}\) up to 14.37 kb/s. The artificial neural network (ANN) architecture has also been proposed for post-equalization to combat non-linear impairments in OWC [25; 26]. The use of an ANN-based equalizer is one of the remarkable solutions adapted in PD-based OWCs, wherein the ANN act as the universal classifiers [27]. In [25], a 170 Mb/s OOK VLC link using an LED with a modulation bandwidth of 4.5 MHz and the ANN-based equalizer at the Tx was reported, where the superiority of ANN equalizers in mitigating intersymbol interference (ISI) was demonstrated compared with other equalization techniques. Note, in OCC with the ANN-based equalizer, the network needs to be trained once for a range of \(T_{\text{exp}}\) with the data being stored in a look-up table within the camera. In [28], the variable transparent amplitude shape code (VTASC) scheme was experimentally evaluated for device-to-device (D2D) (i.e., smartphones) communications in the form of high-density modulation (HDM) with the ANN assisted demodulator. \(R_{b}\) of 2.66 Mbps over a 20 cm long transmission link was achieved. Note, the concept of D2D is one form of the multiple-input multiple-output system, where every pixel is transmitted and detected. Similarly, to allow transmission and reception of information under bad weather conditions, a convolution neural network (CNN)-based OCC was proposed in [29]. The CNN was used for classification and recognition of LED patterns and to decode the transmitted data streams even under an unclear state, where LED patterns are not visible to the camera due to blocking of the transmission path and/or weather conditions. In [30], an OCC link with an ANN-based decoder was reported to mitigate the gap-time effect between two adjacent frames, where OOK was transmitted using an RGB-LED with \(R_{b}\) of 47 kb/s. In [4], an OCC link using a single LED source and Manchester line code with the non-return to zero formats was reported with \(R_{b}\) of 14 kb/s. In this work, the aim is to establish a flickering-free OCC system with improved \(R_{b}\) using a single LED and an ANNs-based equalizer. The key contributions extended from our previous work [31] are:  
* Comprehensive and systematical investigation of the applicability of CP-PAM for the LED- and camera-based VLC. * Development of a practical CP-PAM OCC prototype with a single Luxeon Rebel white LED (SR-01-WC310) and an IS (Thorlabs DCC1645C) as the Tx and the Rx, respectively. * Development of an efficient signal extraction algorithm for the RS-based OCC system. * Implementation of an ANN-based equalizer at the Rx to enhance the system performance. * Development of an experimental test-bed for the proposed system and evaluating it in terms of the Tx's frequency, eye diagrams, and the bit error rate (BER) with and without the ANNs-based equalizer. * Proposing a new measurement metric for assessing the quality of the communications link in terms of the number of row pixels/symbol. The remainder of the paper is organized as follows. Section 2 introduces the proposed CP PAM scheme, whereas Section 3 outlines the ANN equalizer model for IS-based OCC. The experimental setup is described in Section 4. Results and discussion are presented in Section 5. Finally, conclusions are given in Section 6.