Access Point-Coordinated Contention Resolution for Channel Access in Wireless LANs

by Mahboob, Ahmed Mishar

The most widely deployed wireless networking (WLAN) standard, 802.11, grants access of the wireless channel to contending stations (STAs) through the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) mechanism. This approach in general is not scalable, is biased against the network's Access Point (AP), and does not satisfy the Quality-of-Service (QoS) requirements of different flow types. These problems persist even in the most recently ratified standard, 802.11e. In this thesis, we propose a new channel access scheme, ARC (Access Point Coordinated Contention Resolution for Channel Access) that demotes contention and promotes coordination among wireless STAs. ARC enhances the 802.11 contention-based standards with an efficient messaging protocol between the AP and the STAs, in order to communicate congestion information to the AP and channel assignments to STAs. With all packets in 802.11 Infrastructure mode being either transmitted or received by the AP, the AP is in a unique position to maintain flows' congestion information and to make channel assignment decisions. Simulation results reveal that ARC offers better channel utilization; better support for QoS demanding flows than the 802.11 standard, and resolves the bias against the AP.