Multi-Class QoS in 802.11 Networks Using Gentle Decrease of Multiple Contention Windows

—IEEE 802.11 Distributed Coordination Function (DCF) uses a binary exponential backoff algorithm to arbitrate simultaneous channel access by multiple stations. When a station senses that either the shared wireless channel is busy or a collision has occurred, that station must delay the transmission by backoff time. This backoff time, in legacy DCF, is uniformly selected from a common contention window range that, in turn, ensures equal chance of grabbing the wireless medium by each station. Therefore, legacy DCF does not support service differentiation or priority access to the channel. To support service differentiation and increased Quality of Service (QoS), we propose two enhancements to the procedures used for managing contention window in original protocol. These two enhancements can be easily incorporated within the legacy DCF mechanism. First, instead of a common window for all classes, each traffic class is assigned a contention window with minimum and maximum values which a...

• Type: Conference
• Year: 2007
• Where: GLOBECOM
• Authors: Bushra Anjum, Zartash Afzal Uzmi
• Keywords: Backoff Algorithm, Binary Exponential Backoff, Communications, Contention Window, GLOBECOM 2007