Voice capacity analysis of WLANS with channel access prioritizing mechanisms

Voice over IP applications in wireless networks have gained increasing popularity in recent years. As a delay-sensitive real-time application, a VoIP flow is usually given higher priority in accessing the shared wireless channel than delay-insensitive non-real-time flows. In contention-based wireless networks two widely used prioritizing MAC mechanisms are class-dependent arbitration interframe space and class-dependent contention window. In this article we propose an analytical model to evaluate the effect of the two mechanisms on voice capacity (the maximum number of two-way voice flow pairs supportable) of ad hoc mode and infrastructure mode wireless LANs. We show that the AIFS mechanism has a relatively strong effect on WLAN voice capacity in the ad hoc mode, but not in the infrastructure mode; and the CW mechanism, when properly configured, has a mild effect on voice capacity in both modes.