Enhancing cache invalidation in mobile environments

The diversity of services delivered over wireless channels has increased people desire in ubiquitously accessing these services from their mobile devices. However, an ubiquitous mobile computing environment faces several challenges such as scarce bandwidth, limited energy resources, and frequent disconnection of the server and mobile devices. Caching frequently accessed data is an effective technique to improve the network performance since it reduces the network congestion, the query delay, and the power consumption. When caching is used, maintaining cache consistency becomes a major challenge since data items that are updated on the server should be also updated in the cache of the mobile devices. In this paper we propose a new cache invalidation scheme called Selective Adaptive Sorted (SAS) cache invalidation strategy. The proposed scheme overcomes the false invalidation problem that exists in most of the invalidation strategies found in the literature. The performance of the proposed strategy is evaluated. Results showed that a significant cost reduction can be obtained with SAS when measuring performance metrics such as delay, bandwidth, and energy.