## 4 OWC Technologies for the 5G, 6G, and IoT Solutions
### Surveys of OWC-Based 5G and IoT Systems  
A number of researchers around the world are working on OWC-based future communication networks. Table 5 summarizes the key studies on the OWC technologies for the future 5G and IoT systems. No significant work has yet been done on OWC-based 6G communication system. The HBC in [58] is based on head-mounted displays (HMDs). To deploy OCC in HMDs for HBC, the camera of an HMD is used as a receiver, whereas an IR light source is included to the HMD as a transmitter. This work explains the feasibility of HMDs for communication purposes. This system facilitates the users or devices to communicate efficiently with other users or devices using their HMDs. The authors in [63] introduce an LED transmitter and camera receiver-based optical vehicle-to-vehicle (V2V) communication system that can be an emerging technology for Internet of Vehicles. The LED transmitter in a vehicle transmits various data to other camera receivers of a distinct vehicle. An optical communication image sensor is employed in the camera receiver. In [64], the authors present the LiFi/WiFi-integrated architecture that can meet the demands of the 5G system. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Technology** & **Peak Throughput** & **Latency** & **Option** \\ \hline Optical fiber & 100 Gbps & \textless{}1 ms & P2P \\ Microwave & 1 Gbps & \textless{}1 ms/hop & P2P/P2 mP \\ mmWave & 10 Gbps & \textless{}1 ms & P2P \\ FSO & 40 Gbps & \textless{}1 ms & P2P \\ Satellite & 50 Mbps & 300 ms & LOS \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of the achieved data rates and latencies in the existing important backhaul technologies [2; 9; 44]. The universal traffic management system in [65] provides expressway and ordinary road information to cars. This system uses LED headlight as a transmitter for the uplink and multiple PDs with a lens as a roadside receiver. For the downlink, it transmits signal from an LED on a roadside unit and receives the signal using an optical communication image sensor receiver on vehicle. [PERSON] et al. [66] describe the motivating factors for VLC usage to support highly dense users. They present the VLC integration with RF technologies. Selecting of suitable operating conditions for each of the RF and VLC solutions is important to achieve the best outcome. In the relay-assisted VLC system in [67], an amplify-and-forward relay is used to forward the signals and at the same time transmit its own signals. The relay terminal only assists source terminal in forwarding signals to destination terminal. The signals from source terminal are allocated to even subcarriers, whereas the signals from relay terminal are allocated to odd subcarriers. The analysis from source terminal are allocated to even subcarriers, whereas the signals from relay terminal are allocated to odd subcarriers. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Reference** & **Contribution and Research Direction** & **OWC Technology** \\ \hline
[58] & An HBC method based on head-mounted displays, which enables continuous bidirectional communication among multiple users with or without internet connection is proposed. & OCC \\
[63] & An OCC-based optical V2V communication system is developed. & OCC \\
[64] & The primary characteristics of WiFi and LiFi technologies and the possibility for them to coexist for the 5G systems are presented. & LiFi \\
[65] & The feasibility study of the uplink VLC beacon system for the universal traffic management system is presented. & VLC \\
[66] & The feasibility analysis to integrate the VLC with the RF networks is presented. & VLC \\
[67] & A relay-assisted VLC system based on asymmetrically chipped direct current-biased optical orthogonal frequency-division multiplexing for the 5G networks is proposed. & VLC \\
[67] & An amplify-and-forward relay is used in the proposed system to forward the signals from the source terminal and to simultaneously transmit its own signals. & VLC, OCC, and FSO \\ \hline \hline \end{tabular}
\end{table}