## 3 Latest Developments in WLANs  
There is a strong drive to build better WLANs that can support 6G applications in indoor environments. Based on the QoS requirement analyses carried out in Section 2, there are several emerging WLAN candidates that can be considered for 6G integration. Particularly, the following technologies are demonstrated to be the most viable developments that can support 6G applications in the near future. * WiFi 6/6E, WiFi 7;
* 60 GHz WiFi;
* Visible light communication (VLC) and LiFi;
* Optical Wireless Communication (OWC);
* Terahertz communication. WiFi is a well-known WLAN technology that has been used for decades in both home and industry environments. The latest standards of WiFi, WiFi 6/6E, introduced revolutionary changes in the network layer that improve the latency, reliability, and connection density of WiFi networks. The WiFi 7 standard, which is still under development, is expected to fine-tune these features and introduce more coordinated approaches for network operation. In addition, most of the indoor devices are already equipped with WiFi connectivity. Hence, WiFi becomes a natural candidate for the indoor 6G applications. Further, 60 GHz WiFi is also currently under development as the IEEE 802.11 ay standard. This millimetre-wave-range WiFi is best suited for high-data-rate applications, and there are commercial devices such as VR headsets that support this standard. While wide market penetration is yet to happen, industry adoption is promising for 60 GHz WiFi. Another WLAN technology that is being developed to harness the massive unlicensed bandwidth of the optical range is VLC. VLC helps reduce energy consumption by reusing the lighting infrastructure of buildings for communication purposes. In recent years, most of the VLC developments have been marketed as light fidelity (LiFi) systems. LiFi systems are built using VLC as the foundation; however, they offer seamless networking and interfacing capability with existing systems such as Ethernet. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Application** & **Data Rate** & **Latency** & **Reliability** & **Remarks** \\ \hline Healthcare (Remote Surgery) & \(\sim\)2 Gbps & \(<\)1 ms & Very High & High data rate Strict latency and reliability \\ \hline
4k Streaming & 25 Mbps & 6–11 ms 100 Mbps & Medium 10–20 ms & High data rate Delay tolerable to a certain limit \\ \hline AR & 2–20 Mbps (UL) 20–60 Mbps (DL) & 5–50 ms & High & Medium data rate Strict latency and reliability \\ \hline VR & \(<\)2 Mbps (UL) 30–100 Mbps (DL) & 5–20 ms & High & High data rate Strict latency and reliability \\ \hline XR & 300 kbps (UL) 8–30 Mbps (DL) & 10–30 ms & High & Medium data rate Strict latency and reliability \\ \hline Industry 4.0/5.0 & Tens of Mbps & 25 μs & Very High & Medium data rate Strict latency and reliability \\ \hline Smart Homes & \(<\)10 Mbps & \(<\)100 ms & Medium & Massive number of devices \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Quality of Service requirements of upcoming applications. The LiFi standards support a variety of physical layer modes that can serve a wide range of services. For instance, a simple on-off keying (OOK) modulation can serve low-data-rate sensor devices, while the orthogonal frequency division multiplexing (OFDM)-based physical layer is expected to serve high-data-rate applications. Therefore, VLC, along with LiFi, is considered to be a good candidate for 6G integration. OWC is another candidate considered for supporting 6G implementation. OWC uses infrared signals to establish indoor WLANs. Due to its inherent feature of supporting higher bandwidth, interest in optical wireless communication is also rising. Though OWC is not yet standardized, certain physical layer aspects of OWC are already included in the VLC standard. Therefore, it is safe to believe that OWC is next in line for standardization. Moreover, terahertz communication is also gaining momentum in both indoor and outdoor communication.