In this paper, we propose a new mobicast routing protocol, called the HVE-mobicast (hierarchical-variantegg-based mobicast) routing protocol, in wireless sensor networks (WSNs). Existing protocols for a spatiotemporal variant of the multicast protocol called a "mobicast" were designed to support a forwarding zone that moves at a constant velocity, − → v , through sensornets. The spatiotemporal characteristic of a mobicast is to forward a mobicast message to all sensor nodes that are present at time t in some geographic zone (called the forwarding zone) Z, where both the location and shape of the forwarding zone are a function of time over some interval (t start , t end ). Mobicast routing protocol aims to provide reliable and just-in-time message delivery for a mobile sink node. To consider the mobile entity with the different moving speed, a new mobicast routing protocol is investigated in this work by utilizing the cluster-based approach. The message delivery of nodes in the forwarding zone of the HVE-mobicast routing protocol is transmitted by two phases; cluster-to-cluster and clusterto-node phases. In the cluster-to-cluster phase, the clusterhead and relay nodes are distributively notified to wake them up. In the cluster-to-node phase, all member nodes are then notified to wake up by cluster-head nodes according to the estimated arrival time of the delivery zone. The key contribution of the HVE-mobicast routing protocol is that it is more power efficient than existing mobicast routing protocols, especially by considering different moving speeds and directions. Finally, simulation results illustrate performance enhancements in message overhead, power consumption, needlessly woken-up nodes, and successful woken-up ratio, compared to existing mobicast routing protocols.
Due to the explosive growth of the Internet and increasing service demands from all around the world, the cluster-based system that consists of one request-dispatching server and several requesthandling servers has become a cost-effective way to serve the huge amount of service demands. Nowadays, Web servers have to handle more complex types of requests since requests from clients may be mixed with dynamic Web pages, database processing, or multimedia stream data. Therefore, a Web cluster should be designed with intelligent request dispatching policies for supporting various types of service requests.In this paper, we have proposed two new content-aware request distribution policies named Locality-Aware Request Distribution with Replication and Classification (LARD/RC) and Grouped Client-Aware Policy (GCAP) to dispatch requests efficiently in Web clusters providing multiple types of services and running in homogeneous or heterogeneous environments. We have implemented our proposed policies in the LVS-CAD web cluster that can efficiently perform content-aware request dispatching. Performance evaluation shows that our proposed LARD/RC and GCAP policies could dispatch requests of different types to proper back-end servers in a more efficient way to utilize system resources than the other existing policies in both homogeneous and heterogeneous environments.
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