An Adaptive MAC Protocol for Wireless LANs

This paper focuses on contention-based Medium Access Control (MAC) protocols used in Wireless Local Area Networks (WLANs). We propose a novel MAC protocol called Adaptive Backoff Tuning MAC (ABTMAC) based on IEEE 802.11 DCF. In our proposed MAC protocol, we utilize a fixed transmission attempt rate and each node dynamically adjusts its backoff window size considering the current network status. We determined the appropriate transmission attempt rate for both cases where the Request-To-Send/Clear-To-Send (RTS/CTS) mechanism was and was not employed. Robustness against performance degradation caused by the difference between desired and actual values of the attempt rate parameter is considered when setting it. The performance of the protocol is evaluated analytically and through simulations. These results indicate that a wireless network utilizing ABTMAC performs better than one using IEEE 802.11 DCF.Comment: 11 pages, 13 figure

Maximizing Differentiated Throughput in IEEE 802.11e Wireless LANs

The throughput performance of the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC protocol quickly degrades as the number of contending stations increases. To solve this problem, it has been shown recently that adaptive contention window modulation based on channel idle time tracking can be used, generating near optimal throughput. In this paper, we extend the approach for the IEEE 802.11e network, where different QoS classes are defined. We show how to find the class-specific optimal contention window sizes that yield the maximum aggregate throughput while maintaining the target throughput difference between classes. 1