New Channel Access Coordination Functions in Large Scale Wireless LAN Systems

Large-scale wireless LAN systems based on the IEEE 802.11 standards have become the most successful wireless networks deployed in large organizations, such as educational campuses and corporate warehouses. However, the suite of IEEE 802.11 MAC protocols, including DCF, PCF and EDCA mechanisms, was unable to meet the challenges to provide collision freedom and differentiated quality of services. We propose a channel access scheduling protocol based on Latin squares, called DCLASS (Distributed Coordination based on LAtin SquareS), that provisions a set of highly desirable features to large scale wireless networks with stringent performance demands. DCLASS is scalable, fair, and co-exists with IEEE 802.11 nodes with traditional DCF mechanisms. The performance of DCLASS is evaluated using an IEEE standards compliant simulation toolkit, QualNet 4.5, in distributed WLAN systems. The experiment results show the near-optimum performance of DCLASS in contrast to IEEE 802.11 DCF under various scenarios.