Enhanced Distributed Coordination Function of MAC for VoIP Services Using IEEE802.11 Networks

Abstract:

Voice over Internet Protocol (VoIP) is an important service with strict Quality-of-Service (QoS) requirements with in wireless local area networks. The popular Distributed Coordination Function (DCF) of IEEE802.11 Medium Access Control (MAC) protocol adopts Multiplicative Increase and linear Decrease procedure to reduce the packet collision probability in WLANs. In DCF, the size of contention window is doubled upon a collision regardless of the network loads. This paper presents an enhanced DCF scheme to improve the QoS of VoIP in WLANs. This scheme applies a threshold of the collision rate to switch between two different functions for increasing the size of contention window based on the status of network loads. The performance of this scheme investigated and compared to the original DCF using the network simulator NS-2. Under the high traffic loads the packet loss probability decreases with the enhanced DCF compared to the original DCF. Some other parameters like throughput and access delay is decreased with the enhanced DCF.

• Periodical: Advanced Materials Research (Volumes 433-440)
• Pages: 2304-2309
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.433-440.2304
• Online since: January 2012
• Authors: B. Suvarna Vignan, B. Lalu Naick
• Keywords: DCF, Enhanced DCF, QoS, Voice over Internet Protocol (VoIP), WLAN

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