VoIP and Tracking Capacity over WiFi Networks

Wireless VoIP is becoming an increasingly important application in recent years. This fact, coupled with the increasing interest in location based services, strongly suggest that tracking of wireless VoIP clients will become a widely deployed feature in emerging wireless applications. In this paper, we evaluate the capacity of WiFi networks carrying VoIP and tracking sessions for our novel architectures developed specifically to support such applications. We first present an upper bound on a maximum number of users who can be supported by the proposed architecture for tracking only applications via simulations and experiments. We then vary the transmission frequency of tracking data and observe that it has a significant impact on the tracking capacity. Finally, we utilize one of our other locations tracking architecture that is designed for wireless VoIP to investigate how the transmission frequency affects the capacity of combined VoIP and tracking sessions. We develop an insight that at high packetization intervals (e.g. 60 ms) of VoIP traffic, there is a 30% decrease in combined VoIP and tracking capacity in comparison to VoIP only capacity. We further evaluate the capacity of proposed architecture using UDP (User Datagram Protocol) and DCCP (Datagram Congestion Control Protocol) in the presence of TCP (Transmission Control Protocol) traffic. Our studies suggest that compared to UDP, DCCP not only improves the combined VoIP and tracking capacity but also enables TCP to get a reasonable bandwidth share.