# Estimating PQoS of Video Conferencing on Wi-Fi Networks Using Machine Learning
## 2 Materials and Methods
\tag{2}\]  
Because packet loss can significantly affect the quality of video conferencing, the impact of packet loss ratio on the \(R\)-factor was magnified and calculated as follows:  
\[R\ =\ \ R-(2.5\times Packet\_loss) \tag{3}\]  
Finally, the \(MOS\) values were calculated for different \(R\)-factors using the ITU E-model [10], as follows:  
\[MOS=\ \ \ \left\{ \begin{array}{l l}1&R\leq 0\\ 1+0.035R+(0.000007R\times(R-60)\times(100-R))&0<R<100\\ 4.5&R\geq 100\end{array} \right. \tag{4}\]  
The abovementioned method facilitates calculating \(MOS\) values using parameters extracted from WebRTC internals so that \(MOS\) values can be calculated for both audio and video sessions between each wireless client and the cloud-based video conferencing endpoint. This study leveraged the AirTies 4920 and the Zyxel 5501 AP/Internet gateway as examples of off-the-shelf Wi-Fi APs to test wireless networks operating at various 802.11g/n/ac/ax standards over 2.4 GHz and 5 GHz frequency bands. Four groups of experiments were conducted to investigate the impact of wireless conditions on the quality changes of video conferencing in homes and buildings. The AirTies 4920 AP was used to test 802.11g/n/ac standards, whereas Zyxel 5501 was primarily used to test the 802.11 ax standard. In each experiment, four wireless clients connected to an AP establishing video conferencing calls. For testing 802.11g/n/ac standards operating in both 2.4 and 5 GHz frequency bands, one Dell Latitude 5480 laptop equipped with Intel 8265 802.11g/n/ac wireless adapter, one HP Elitebook 8460P laptop equipped with Intel Centrino 6205 802.11g/n wireless adapter, one Lenovo E531 laptop equipped with Realtek 8812 BU 802.11g/n/ac external wireless adaptor, and one Microsoft Surface tablet equipped with 802.11g/n/ac Marvell AVASTAR wireless adapter connected to the AirTies 4920 AP. For testing 802.11 ax in both 2.4 and 5 GHz frequency bands, four Intel NUC PCs equipped with Intel AX200 PCI-e wireless adapters connected to the Zyxel 5501 AP. In this study, Wi-Fi networks operating at 802.11g/n 2.4 GHz, 802.11 ac 5 GHz, 802.11 ax 2.4 GHz, and 802.11 ax 5 GHz were tested, and in each test, clients deployed in two different scenarios, including all devices being near the AP in one room as well as clients distributed in different rooms. Figure 1a depicts the first setup, a simulated round-the-table scenario where four wireless devices are connected to an AP that is approximately two meters from each device in one room. Figure 1b depicts the second setup, in which four wireless devices are located in different rooms to simulate the most common use case in homes and buildings (e.g., a home school or home office). The AirTies 4920 and Zysxel 5501 leverage a customized Linux operating system to control hardware. Each vendor customized the Linux operating system to control a different wireless adapter embedded in the AP so that available tools in each device return different parameters. One of these tools is the \"wl\", which allows collection of 802.11 performance parameters such as wireless adaptor counters, multimedia access category counters, packet counters, and specific counters for each connected client. We developed a Bash script to collect wireless performance parameters, security, and privacy configuration every second. In doing so, the Bash script collected more than 190 wireless network parameters for each wireless adaptor and more than 48 parameters for each connected client to the AP. Then, the script sends collected parameters to an Elastic Stack [14] platform as our cloud-based monitoring platform, which parses data upon arrival and indexes them to the Elasticsearch for further analysis. In order to capture the impact of individual wireless devices on the perceived quality of the existing video conferencing session, wireless devices joined the call incrementally, one after another. Each client joined the call for 14 min in each test, while the Bash script collected the 802.11 network performance parameters on the AP every second.