VoWiFi Cell Capacity Estimation Using Fifth Generation WLAN Standard

The growth of Wireless Local Area Network (WLAN) deployment specifically over the existing infrastructure is increasing tremendously. Such an infrastructure-based WLAN, commonly known as Wireless Fidelity (WiFi) network, needs to support voice service since in general it contributes a significant portion of the traffic supporting personal communication. In this context, Voice over Internet Protocol (VoIP) over WiFi or Voice over WiFi (VoWiFi) is one amongst the very prominent solutions. To ensure Quality of Service (QoS) for VoWiFi calls, it is essential to develop an adequate call admission control (CAC) policy. Such policy requires VoWiFi cell capacity. In this paper, we have derived analytical models to find capacity of the IEEE 802.11ac standard Access Point (AP) providing VoWiFi service. To analyze WLAN AP capacity for VoWiFi service, we have used DCF Inter-frame Spacing (DIFS) for sensing channel status before sending data from one station to another and Short Inter-frame Spacing (SIFS) is used for acknowledgement, Request To Send (RTS) and Clear To Send (CTS) frames. Further, we have used the compressed RTP (cRTP) protocol to optimize VoIP call bandwidth. Using our proposed analytical model, we have estimated VoWiFi cell capacity using different voice codecs like G.729 and G.723.1.