## 5 Automation and Teleoperation
### Technology Description  
#### 5.2.1 Wi-Fi  
The wireless fidelity (Wi-Fi) is a set of networking protocols. It is the trademarked and most used standard for devices in a wireless local area network (WLAN). The Wi-Fi 5 standard introduced in 2014 was succeeded by Wi-Fi 6 (2019) and now Wi-Fi 6E in 2020 [43]. The main difference between the standards is their accessible GHz spectrum. WiFi 6E is the extension of the 2.4 GHz and 5 GHz spectrum to include the 6 GHz frequencies to be used in an unlicensed manner [43]. Wi-Fi 6E operates in the 6 GHz band from 5.925 to 7.125 GHz, 1200 MHz from 5.925 to 7.125 GHz having been allocated for Wi-Fi applications. Previously, Wi-Fi standards (including Wi-Fi 6) used the 2.4 GHz band (2400 to 2495 MHz) and the 5 GHz band (5170 to 5835 MHz) [43]. This new band allows Wi-Fi 6E to operate with 14 additional 80 MHz channels and seven additional 160 MHz channels. This talk about channels provides a quantifiable term for areas without crosstalk. This is an often-cited problem in dense urban apartment areas with each household having a router. In numbers, the old 2.4 GHz standard could have three 20 MHz channels or combine them via multi-channelling to a single 60 MHz channel [44]. 5 GHz units could use all of 19 channels, with 20 MHz combining them to up to two 160 MHz channels [44]. With 6E, even 24 channels are possible, although the upper limit in the frequency and its usage varies heavily for different nations or regions [44]. On one 160 MHz channel, multi-Gbps throughput is possible [43]. Therefore, Wi-Fi 6E can have three separate maximal bandwidth operations at the same time if it uses the full spectrum and therefore occupies the entire wireless communication spectrum aside from millimetre waves from 5G discussed later. The improvements in the protocols in combination with the possibility to use the large number of possible channels in all three spectra set of Wi-Fi, simultaneously, is a huge advancement for the Wi-Fi technology in terms of the available number of usable channels, resulting in the potential bandwidth and number of users [45]. For these reasons, Wi-Fi 6 has been considered an alternative to a (private) 5G cellular network for communication and data exchange in coal mines [35]. Wi-Fi has a different set of characteristics stemming from its targeted indoor application compared to cellular networks, namely, the lower coverage area per basis and the lower power consumption [46]. While it has been calculated that the 5G infrastructure can be replaced in a coal mine with Wi-Fi 6, one more aspect of how the Wi-Fi relevant bands are structured can be analysed [16]. Wi-Fi 5, 6 and 6E had a big focus on increasing the number of channels per band, which a single unit like a home router could send and receive data on. This is of significance, as all routers in proximity to each other must share this finite number of channels. This can happen quite fast in, for example, apartment complexes with each household owning a dedicated router [1; 43]. Mining operations do not suffer from these problems, as the routers are placed for efficiency and urban signals are minimal or zero. This unique situation could enable the usage of multiple bands simultaneously for a great data rate improvement. This is already done by some router models but only on the scale of a few channels [47]. An important aspect of the discussion about the new devices with WiFi 6 and higher is the connection between devices on the higher frequency bands, which are less robust in harsh conditions and over greater distances. When a connection at 5/6 GHz can only be partially maintained, the network will only be established in that section or situation on the more robust 2.4 GHz band [48]. This results in a reduction in bandwidth, higher latency and fewer possible users-potentially not fulfilling needed network specifications under some circumstances, since the network is not managed or prioritized. However, the 2.4 GHz range is greater and the signal has greater propagation or even penetration [49].