Dynamic QoS Adaptation for Mobile Middleware

Computation and networking resources in mobile operating environments are much scarcer and more dynamic than in desktop operating environments. Mobile applications can leverage on the benefits of adaptive computing to optimize the quality-of-service (QoS) delivery based on dynamic contextual situations. Fuzzy control models have been successfully applied to various distributed network QoS management systems. However, existing models are either application-specific or limited to abstract modeling and simple conceptual scenarios that do not take into account overall model scalability. Specifically, the large number of QoS parameters in a mobile operating environment causes the rule-explosion problem, in which an exponential increase in the number of rules correspondingly increases the demand for processing power to infer the rules. Hierarchical fuzzy systems were introduced to reduce the number of rules using hierarchical fuzzy control, in which correlated linguistic variables are hierarchically inferred and grouped into abstract linguistic variables. In this paper, we propose a mobile QoS management framework that uses a hierarchical fuzzy control model to support a highly extensible and structured adaptation paradigm. The proposed framework integrates several levels of QoS abstractions derived from user-perceived requirements. It also maps these abstractions to appropriate QoS resources that drive the development of mobile services that mitigate the effects of varying mobile environments.