# Adaptive Polling Medium Access Control Protocol for Optic Wireless Networks
## 3 Problem Description and Assumptions  
OWNs originate from the VLC concept wherein visible light is a conduit of signals from the source to the destination [47]. It should be noted that the VLC aims at providing point to point communication via visible light spectrum, whereas OWNs such as the LiFi extends the idea of point to point communication to full networking concepts such as broadcasting, multi-casting and point to point communication [13]. LiFi is the prominent example of OWNs that exploit traditional LEDs available in our surrounding to provide fast data transmission [13]. The IEEE 802.15.7 standard for VLC allows three types of network topologies namely peer-to-peer, broadcast and star topologies [12]. Accessing shared resources in star and broadcasting topologies can be challenging and often causes network performance degradation. In this study, we investigate the problem of bandwidth assignment for multiple users sharing the same visible light access point (VLAP). The visible light nodes (VLNs) in this context refer to normal devices such as computers and mobile phones that are enabled with optic transmitters such as LEDs and optic receivers such as photo-diodes. Similarly, the VLAP refers to the access point that provides \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Study** & **Type** & **Transmission Medium** & **Application** & \begin{tabular}{c} **Waiting** \\ **Time** \\ \end{tabular} & **Utilization** & **Fairness** \\ \hline [PERSON] et al. [29] & Contention & Radio over Fiber (RoF) & Outdoor & Yes & No & No \\ \hline [PERSON] et al. [30] & Contention & Radio over Fiber (RoF) & Outdoor & Yes & No & No \\ \hline [PERSON] et al. [31] & Contention & Radio over Fiber (RoF) & Outdoor & Yes & No & No \\ \hline [PERSON] et al. [32] & \begin{tabular}{c} Channelization \\ (TDMA) \\ \end{tabular} & Visible light spectrum & Indoor & No & No & No \\ \hline [PERSON] et al. [33] & \begin{tabular}{c} Non-contention \\ (Adaptive Polling) \\ \end{tabular} & EPON & Outdoor & Yes & Yes & No \\ \hline [PERSON] et al. [34] & Contention & Visible light spectrum & Outdoor & No & Yes & No \\ \hline [PERSON] et al. [35] & Contention & Visible light spectrum & Indoor & No & No & No \\ \hline [PERSON] et al. [36] & Contention & Visible light spectrum & Indoor & No & No & No \\ \hline [PERSON] et al. [37] & Contention & Visible light spectrum & Indoor & No & Yes & No \\ \hline [PERSON] et al. [38] & \begin{tabular}{c} Channelization \\ (TDMA and CDMA) \\ \end{tabular} & Visible light spectrum & \begin{tabular}{c} Vehicular \\ Communication \\ \end{tabular} & Yes & Yes & No \\ \hline [PERSON] et al. [39] & \begin{tabular}{c} Non-contention \\ (Multi-Polling) \\ \end{tabular} & Radio spectrum & Indoor & Yes & No & No \\ \hline [PERSON] et al. [40] & \begin{tabular}{c} Channelization \\ (TDM) \\ \end{tabular} & Visible light spectrum & Indoor & No & Yes & No \\ \hline [PERSON] et al. [41] & Contention & Radio and Visible light spectrum & Indoor & No & Yes & No \\ \hline [PERSON] et al. [42] & Contention & Visible light spectrum & Indoor & No & Yes & No \\ \hline [PERSON] et al. [43] & Contention & Visible light spectrum & Indoor & Yes & Yes & Yes \\ \hline [PERSON] et al. [44] & Contention & Visible light spectrum & Indoor & Yes & Yes & No \\ \hline [PERSON] et al. [45] & Contention & Radio and Visible light spectrum & Indoor & Yes & Yes & No \\ \hline [PERSON] et al. [46] & Contention & \
\begin{tabular}{c} Radio and Visible light \\ spectrum \\ \end{tabular} & Indoor & Yes & Yes & No \\ \hline
\begin{tabular}{c} This study \\ (Adaptive Polling) \\ \end{tabular} & Visible light spectrum & Indoor & Yes & Yes & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Research publications on medium access control (MAC) protocols for optical wireless networks (OWNs). Internet connectivity via visible light spectrum. The VLAP is also enabled with an LED that transmits signals via light rays to several VLNs that fall within its angle of irradiance and has photo-diodes for visible light signal reception.