Using Smart Triggers for Improved User Performance in 802.11
The handoff algorithms in the current generation of 802.11 networks are primarily reactive in nature, because they wait until the link quality degrades substantially to trigger a handoff. They further rely on instantaneous signal strength measurements when choosing the best AP. This approach leads to handoff delays on the order of 1-2 seconds that are unacceptable for delay sensitive applications such as VoIP. We propose a fundamentally new approach to handoffs that is based on continuous monitoring of wireless links. In our approach, a client measures the beacon strengths of all the APs operating on the current, and the overlapping channels, and makes its handoff decisions based on the long-term, and short-term trends in these signals. We show through experiments
in a campus wireless network that our proposed algorithms result in more than 50% reduction in average handoff delays, while having the potential to improve overall user performance. Our algorithms have been implemented in today's hardware, and unlike other proposed roaming algorithms in the literature, need no infrastructure support.
Joint work with Vivek Mhatre. This paper appeared in ACM Mobisys 2006.
The success on managing large networks and the services
running on them is closely
related to the quality of the operational control of the net and the
feedback from the customers. As these networks get complex and the
services ubiquitous, there is a need for more flexible, dynamic and
abstract ways to measure the quality of the services provided to
customers. In this talk we introduce the idea of using ontologies to
structure the management information in such a way that it would provide
some key factors we understand will be of importance for managing
services in the future: sharing and collaboration between providers (and
users); high level common specifications; on-the-fly mapping of
policies; context awareness; etc. We will spend some time demonstrating
the potential use of ontologies on a similar problem: security
management. The creation of two ontologies, Security Incident and
Vulnerabilities, with the definition of classes, relationships and the
possibilities of data correlations, will be described.