# Comprehensive Survey on VLC in E-Healthcare: Channel Coding Schemes and Modulation Techniques
## 1 Introduction  
The field of e-healthcare has experienced significant growth, due to its ability to enable remote patient monitoring, telemedicine consultations, and efficient exchange of medical data among healthcare professionals. Wireless communication technologies are increasingly being integrated into medical body area networks, to enhance flexibility and convenience for caregivers and patients. However, traditional solutions that rely on RF technologies face several challenges, including electromagnetic interference with precision medical equipment [1, 2], saturation of the radio spectrum, and limited bandwidth. VLC emerges as an innovative alternative that utilizes white light-emitting diodes (LEDs) for both information transmission and illumination. In this context, VLC offers distinct advantages over RF communications, operating in a different part of the electromagnetic spectrum with wavelengths between 380 and 750 nm and frequencies ranging from 430 to 790 THz--10,000 times larger than the entire RF spectrum [3]. This frequency range is safe for human exposure, does not interfere with sensitive electronic devices, and is not licensed, providing abundant free bandwidth. Additionally, the VLC is energy-efficient, as it uses LEDs for communication and lighting [2, 4]. VLC exhibits substantial promise within medicine, offering significant advantages to healthcare professionals and patients. Several prevalent applications of VLC in the medical domain include patient monitoring, indoor navigation and positioning, interactive dissemination of patient information, intercommunication between medical devices, medical imaging, communication during surgical procedures, and data transmission on wearable devices [2; 5]. By integrating VLC technology into medical body area networks, healthcare providers can enhance flexibility and convenience for caregivers and patients in various medical applications. This integration leads to improved patient care, streamlined operations, and greater overall healthcare efficiency. In addition, patients benefit from a more seamless and interactive healthcare experience [6; 7; 8; 9]. One of the primary applications of VLC technology is the real-time transmission of patient data from medical sensors, such as heart rate monitors, blood pressure monitors, and oxygen saturation sensors. VLC systems also enable the reception of location-based information and access to medical records, treatment plans, educational content, and entertainment options. Furthermore, VLC technology facilitates the transmission of high-resolution medical images, such as X-rays, magnetic resonance imaging (MRI), and computerized tomography (CT) scans, from imaging devices to display screens or viewing stations used by healthcare professionals within hospital settings [10; 11]. The use of VLC technology in healthcare systems presents some significant challenges. For light signals to be transmitted effectively, there must be an unobstructed path between the transmitter and the receiver, as the light must propagate in a straight line. Ambient light interference can degrade signal quality, affecting the accuracy and reliability of data transfer. In VLC, signal attenuation can occur, due to factors such as distance, material properties, or environmental conditions, with indoor environments being the most critical. Maintaining a high signal-to-noise ratio (SNR) is critical for reliable data transmission, which can be challenging in specific medical settings [12]. To overcome these obstacles, ongoing research and development efforts focus on improving VLC technology. Recent advances in signal processing techniques and standardization efforts suggest that VLC has the potential to become a more robust and reliable communication solution for patient monitoring in the medical field [13]. Hence, the current analysis and identification of reviews are grounded in the findings and methodologies of previous researchers.