## 2 Literature Review
This study provides solutions for multipurpose indoor optical IoT regardless of the device used. Furthermore, Ref. [30] developed efficient OCC for IoT applications to overcome the distance limit and low data rate on existing OCC implementations. In this work, the proposed OCC used an \(8\times 8\) LED matrix to increase the operational distance up to 2 m and to reduce BER, which is suitable for use in an indoor industrial environment. The main purpose of this research is to obtain an efficient classification pattern and widen the communication distance with a data rate of more than 256 bps. Based on the results, this study achieves efficient classification of 2D signal patterns on LED matrices and can detect the pattern from a far distance. However, there are several weaknesses, such as performance limitations on further distance and higher data rates. In addition, factors affect system performance, especially camera settings, and characteristics such as resolution and brightness, influencing pattern recognition and communication errors. IoMT, as a subcategory of IoT, is still relatively unexplored in the healthcare context, particularly in the use of OCC. However, recent studies in the field of OCC for eHealth [20; 31; 32] have developed monitoring systems that enable patient surveillance in various settings such as homes, hospitals, indoor and outdoor areas, intensive care units, ambulances, airplanes, ships, and ICUs. OCC is applied to measure photoplethysmography (PPG) signals, analyze emotions, determine blood oxygen levels [32], and assist in patient diagnosis [20]. In OCC-based healthcare systems, data are collected from various LEDs worn by patients. This data collection is conducted securely and reliably without causing interference, ensuring high quality of service (QoS) [33]. OCC offers several advantages that can benefit the healthcare sector:  
* OCC offers a wide spectrum, low cost, and lower system costs [20]. It also has no electromagnetic interference (EMI), which can lead to failures in medical devices [34];
* Visible light waves have no adverse effects on human health [35], and non-flicker technology in light waves can be used with modulation frequencies exceeding 200 Hz without posing a threat to human eyes, unlike the potential negative effects of RF waves on human health [36];
* The increased bandwidth in current communication systems often requires the use of higher-frequency waves, which can negatively impact human health [36];
* RF systems use electromagnetic waves to transmit information, which is potentially harmful to human health [20; 35];
* OCC provides a readily deployable LiFi solution using a smartphone camera [37] for communication, positioning, indoor navigation, and augmented reality without the need for additional equipment such as photodiodes [38]. Based on various studies in the field of IoT, OCC technology exhibits significant potential as a reliable and versatile application for both outdoor and indoor environments. This enables effective and efficient implementation across IoT scenarios. Although the use of OCC in IoMT is still underexplored, there has been a significant increase in research within the eHealth context. To enhance continuous and real-time health monitoring of patients, particularly through remote monitoring, we developed an IoMT system scheme focused on indoor scenarios. This system integrates OCC-based WBAN using CCTV cameras, which are widely available in various buildings, especially in healthcare facilities or hospitals. We also considered important factors such as the capacity to serve multiple patients, system coverage, and the ability to monitor patients' positions or locations simultaneously in different places, all of which are strengthened by the use of artificial intelligence.