VoWiFi Cell Capacity Estimation using IEEE 802.11ax

The IEEE 802.11 standard is commonly used to provide wireless networking capabilities for different applications. Although the format was designed mainly to provide data transmission capability, it also became a common medium for speech communication. The reasons are twofold: extensive Wireless Local Area Network (WLAN) connectivity and the low cost of making voice calls on this network. To provide the Quality-of-Service (QoS) of Voice over WiFi (VoWiFi) calls, an appropriate policy for call admission control is required. Such a policy requires VoWiFi user capacity of the WLAN cell. In this paper, we have proposed an analytical model to estimate the number of VoWiFi calls possible in IEEE 802.11ax standard Access Point (AP) (i.e. sixth generation Wireless Fidelity (WiFi) standard) and compared with earlier standards like IEEE 802.11b/g/n/ac. We have used DCF Inter-frame Spacing (DIFS) to detect channel status before transmitting data from one station to another and Short Inter-frame Spacing (SIFS) before sending acknowledgement, Request To Send (RTS) and Clear To Send (CTS) frames. We have used the Compressed RTP (cRTP) protocol to enhance VoWiFi cell capacity. We have measured VoWiFi cell capacity using G.729 voice codec.