# A Review on LiFi Network Research: Open Issues, Applications and Future Directions  
[PERSON]  
Department of Communication Technology and Network, University Putra Malaysia (UPM),  
Seri Kembangan 43300, Selangor, Malaysia; [EMAIL_ADDRESS] (R.B. ); [EMAIL_ADDRESS] (Z.M.H. ); [EMAIL_ADDRESS] (A.M.)  
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[PERSON]  
Department of Communication Technology and Network, University Putra Malaysia (UPM),  
Seri Kembangan 43300, Selangor, Malaysia; [EMAIL_ADDRESS] (R.B. ); [EMAIL_ADDRESS] (Z.M.H. ); [EMAIL_ADDRESS] (A.M.)  
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[PERSON]  
Correspondence: [PERSON]RESS] 22  
transmission speeds. Many studies have used and tested different lights to transmit data. The main focus was on Red, Green and Blue, which is also known as RGB [2]. One of the most important events that has made history in the 1880s was the invention of the photophone by [PERSON] and his team [11]. The photophone was an instrument that conveyed speech wirelessly via a beam of light. The first documented research in modern VLC began at the Keio University in Japan in Nakagawa Laboratory [12]. In 2006, CICTR researchers from the State University of Pennsylvania suggested the combination of power transmission with LED technology to ensure adequate broadband access. This study specifically focused on data transfer that utilized LEDs with VL. This channel provided inexpensive and sufficient illumination and home networking. Two years later, the European Union started its VLC research project, known as OMEGA [13]; they aimed to develop a high-speed domestic service network at rates of up to 1 Gbit/s. The maximum performance cap for the network was 1.25 Gbit/s. In 2008, the United States National Science Foundation conducted a range of tests to enhance the usage of smart lighting wireless communication network [13]. Funding was initiated to use LED bulbs as comparable points of communication technologies. Many other research ventures have been conducted in the European Union and the United States. Some of these works have contributed substantially to the establishment of LiFi at the Edinburgh University in Scotland. The development of the VLC technology began in 2006 and was primarily based on the two-way data communication. Subsequently, paving the way for the growth of LiFi technology. LiFi was introduced to the world via the [PERSON] 2011 TED talk. Wireless data transmission by light bulb was demonstrated in the talk. During the talk, [PERSON] presented a variant of \"The Light Fidelity\". In 2012, he helped assess the LiFi Product Marketing Business, the first company to combine LiFi instruments with existing LED lights and named it Market-Built Equipment Original Equipment Manufacturer (OEM) [13]. One of the controversial concepts about LiFi and VLC is their common characteristics where many studies have stated and treated them as one, while others assume, they are different. Given the fact both use visible light as a medium of communication, it is important to point out the features and various components within different approaches and applications that distinguish LiFi from VLC. Specifically, LiFi is recognized as one of the most important technologies for 5G [14]. It is based on the VLC approach, which uses LEDs that are extensively used in houses, workplaces, and road systems to enable high-speed wireless communication. The transmission rates of over 3 Gb/s may be achieved utilizing Orthogonal Frequency Division Multiplexing (OFDM) [15]. However, unlike VLC, where the primary goal is to create a point-to-point link between different devices using visible light, LiFi is a light-based data transmission system that allows for fully interconnected cellular infrastructure, including bi-directional multi-user communication. Due to VLC's restricted transmission range, LiFi leads to further reduced cell size, which raises the size of the service area attocell [15]. LiFi is a high-speed wireless connection system [16] that requires multiple access points (APs) that form dense optical attocellular networks [4].