An analysis of the channel utilization for call admission control in voice over WLAN

Abstract

In this paper, we present an analytical method for effectively evaluating the channel utilization of voice calls in voice over WLAN systems. The method is under realistic assumptions general enough to deal with various cases of mixed traffic sources and transmission conditions. The accuracy and effectiveness of our method are validated through experiments. The method provided a basis for a prototype call-admission-control system for VoWLAN, in an attempt to enable an operational VoWLAN system with quality-of-service support.

Capacity analysis and resource management of an integrated WiMAX & Wi-Fi access system for VoIP

“…While WiMAX, which has a TDMA-based MAC, is intrinsically well-suited to admission control for QoS service, implementing an effective admission control mechanism for CSMA-based Wi-Fi, however, is not trivial. In [6], a method of accurately predicting the WLAN bandwidth usage, and then the maximum number of concurrently admissible VoWLAN (VoIP over WLAN) calls for acceptable voice quality with considerations on the system conditions such as radio signal strength and traffic source characteristics, is introduced. The method provides a basis for effective VoWLAN admission control.…”

“…The traffic load to Wi-Fi cell i is a i (i=1, ..., m), and that directly to the WiMAX cell is a 0 , in the unit of erl (the average number of arrivals in a unit of time, multiplied by the average service time of a call). Each Wi-Fi cell may have a different size of bandwidth resources assigned for the VoIP traffic, in terms of the maximum number of concurrently admissible VoIP calls, depending on various factors including the radio conditions of the terminals and the traffic source characteristics [6]. This kind of traffic model has long been studied in the traffic theory for traditional PSTN telephone systems, where the well-known equivalent random method is applicable for approximate analysis (see [7]).…”

“…In this example, we have a total of 10 identical Wi-Fi cells each having a resource size of simultaneously serving 7 calls (roughly corresponding to the case of an IEEE802.11b WLAN serving G.711 VoIP calls with a packet interval of 20ms [6]), and an equal load of a erl. The Wi-Fi load intensity is thus…”