The Voice Capacity of WiFi for Best Effort and Prioritized Traffic

—Crucial to supporting voice over 802.11b is the knowledge of voice capacity (N c) of a single Access Point. This paper provides an analytical formulation of N c in the case where all traffic in the network is voice. Our formulation, which can apply to a range of voice codec specifications, are verified by detailed simulations. We also investigate how to deliver, within the 802.11b standard, priority service to voice in the presence of best effort background traffic. It is known that the voice capacity degrades very quickly in the presence of other traffic sources if all packets are treated as best effort. Using an experimental deployment in which all voice packets are prioritized by having their channel back-off times set to zero, we determine the rate of the best effort background traffic below which our analytical formulation of voice-only capacity remains useful. I. INTRODUCTION IRELESS local area networks have been widely and rapidly deployed, both in public spaces (airports, campuses, etc.,) and in the home networking environment. The most common protocol run over these networks is that based on the IEEE 802.11b standard [6], commonly known as WiFi. Services and applications running over WiFi are evolving from time-insensitive data applications to time-sensitive real-time applications. In particular, VoIP (Voice over IP) is anticipated to be widely deployed over WiFi in the next few years.