Covenant: An architecture for cooperative scheduling in 802.11 wireless networks

Wireless networks based on 802.11a/b/g protocols have gained wide-spread acceptance in both enterprise as well as home networks. However, these devices lack native support for many advanced features such as service differentiation, etc., that are required in specific application domains. In this paper, we propose Covenant, a software based cooperative scheduling framework to provide a rich set of features for applications that require nodes to cooperate with each other to satisfy system-wide objectives. We propose a novel 2 1/2-stage pipeline architecture as an efficient mechanism to implement cooperative scheduling among multiple nodes. We demonstrate how Covenant can be easily implemented in software, thus requiring absolutely no hardware or firmware changes to the already widely installed base of 802.11a/b/g based wireless devices. We also evaluate, using a real Linux based test-bed with Covenant drivers, the efficacy of the approach on two different scheduling disciplines: proportional priority and strict priority. We demonstrate that these scheduling disciplines are effective in providing service guarantees to multimedia applications even in the presence of other competing traffic.