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  • Research Article
  • Open Access

Modified Isochronous Coordination Function for Enhancement of VoIP Call Capacity over IEEE 802.11 WLAN

EURASIP Journal on Wireless Communications and Networking20072008:218076

Received: 17 March 2007

Accepted: 22 October 2007

Published: 12 November 2007


VoIP over IEEE 802.11 wireless local area network (WLAN) is growing very fast and is providing a cost effective alternative for voice communications. WLANs were initially set up to handle bursty nonreal time type of data traffic. Therefore, the wireless access protocols initially defined are not suitable for voice traffic. Subsequently, updates in the standard have been made to provision for QoS requirements of data, especially the real time traffic of the type voice and video. Despite these updates, however, transmitting voice traffic over WLAN does not utilize the available bandwidth (BW) efficiently, and the number of simultaneous calls supported in practice is significantly lower than what the BW figures would suggest. Several modifications have been proposed to improve the call capacity, and recently isochronous coordination function (ICF) was introduced to mitigate the problem of low call capacity. In this paper, we propose a modified ICF which further improves the performance in terms of the call capacity. The proposed scheme uses multiplexing and multicasting in the downlink to substantially increase the call capacity.


Wireless Local Area NetworkWireless AccessFull ArticleData TrafficTime Type

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Authors’ Affiliations

Department of Electrical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India


© Sanjaya Gupta et al. 2008

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.