## 7 Visible Light Communication and LiFi
### LiFi: IEEE 802.11 bb  
LiFi is another VLC technology developed in the recent years, and is the first standard to work on LiFi products. With the cooperation between IEEE 802.15.13 and ITU G.9991 standards, the IEEE 802.11 bb standard was established to facilitate a standardized LiFi mass market [74, 75, 76]. The 802.11 bb standard specifies the following enhancements in the physical layer and the MAC layer to support emerging indoor technologies [74, 76].  
* 380 nm to 5000 nm band for uplink and downlink transmissions;
* All modes of operation achieve minimum single-link throughput of 10 Mbps;
* At least one mode of operation that achieves single-link throughput of at least 5 Gbps;
* Capability of working on different modulation bandwidths among solid light sources;
* Channel access via hybrid coordination function (HCF);
* Coexistence and detection with overlapping basic service set (OBSS);
* Power management modes.  
The IEEE 802.11 bb standard is still under development. As stated earlier, the IEEE 802.11 bb standard supports a wide range of physical layer data rates, and includes advanced MAC layer features [77]. The physical layer of IEEE 802.11 bb was expected to be derived from both the IEEE 802.11 standard and the G.vlc standard. The IEEE 802.11 chipsets operate between 20-160 MHz of bandwidth and will require minimum changes to be converted to light communication frequencies. On the other hand, G.vlc includes many optimizations, such as adaptive bit loading, that result in good performance under frequency-selective channels. However, recently, the task group has abandoned the G.vlc physical layer and started working exclusively on IEEE 802.11-based physical layers.  
The MAC layer and channel characteristics are still emerging for this particular standard [76, 78]. However, it is safe to believe that the MAC layer would be similar to that of IEEE 802.11, with specific modifications for the optical physical layer. Therefore, the IEEE 802.11 bb products will have familiar underlying technology and will fast-track the deployment of LiFi.  
There are a few companies that already provide LiFi solutions for domestic and industrial uses. For instance, pureLiFi is a pioneer in LiFi products that supports a range of consumer devices and adheres to common communication standards [79]. Oledcomm is also a LiFi vendor, which is known for its range of products and its data rate. The latest LiFi modules of Oledcomm can reach the Gbps range [80]. Another key player in the LiFi space is Velmenni, which provides both indoor and outdoor solutions. However, the outdoor solutions are point-to-point links, which are similar to free space optics solutions [81].  
Due to the abovementioned advancements in the physical layer supporting higher data rates and easy adaptation of the matured upper layer protocols, VLC technology is a good candidate to be considered for integrating into the 6G ecosystem to support emerging indoor applications. VLC can be used to complement 6G wireless connectivity by providing connectivity for devices that are not equipped for RF communication and/orin environments where RF signals may cause electromagnetic interference with other devices, such as in hospitals and factories. Further, VLC can complement the 6G ecosystem where a high data rate and low-latency connectivity is required, with direct line-of-sight connections such as vehicle-to-vehicle communication supporting the implementation of fully autonomous vehicles.