Adaptive Caching Strategies for Context Management Systems

Efficient access strategies to dynamically changing context information is an important functionality in many scenarios of context-sensitive networking. Access delay requirements and bounded communication overhead can be achieved via caching of the remotely available context information; meeting such QoS constraints is particularly relevant for wireless settings. However, caching increases the probability that the used context information does not correspond to its true value at the remote node. The paper develops a quantitative analytic model to calculate mismatch probability, mean access delay, and network overhead as a function of the cache lifetimes, network delays, request rates, and properties of the dynamically changing context information. Parametric studies of these performance metrics provide insights into the impact of different distribution types and parameter choices on these performance metrics. Due to monotonicity properties, the choice of optimal cache durations can be reduced to numerical solutions of the analytic equations. Results for two optimality criterions are presented and discussed. The quantitative models presented in this paper allow to implement adaptive caching strategies for context-sensitive networking functionalities.