ABSTRACT

In this chapter we propose a new service classification strategy [38], [42] for hybrid broadcasting to support the differentiated QoS in wireless data networks. The major novelty of our work lies in separating the clients into different classes and introducing the concept of a new selection criteria, termed as importance factor by combining the clients’ priority and the stretch (i.e., max-request min-service-time) value. The item having the maximum importance factor is selected from the pull queue. The service providers now provide different service level agreements (SLA), by guaranteeing different levels of resource provisioning to each class of clients. Figure 7.1 shows one such service level agreement from the service provider by offering more bandwidth allocation for highest priority clients (e.g. Gold or Silver category of users); than for the lower priority clients basic users. The QoS (delay and blocking) guarantee for different classes of clients now becomes different, with the clients having maximum importance factor achieving the highest level of QoS guarantee. The performance of our heterogeneous hybrid scheduler is analyzed using suitable priority queues to derive the expected waiting time. The bandwidth of the wireless channels is distributed among the client classes to minimize the request blocking of highest priority clients. The cutoff point, used to segregate the push and pull items, is efficiently chosen such that the overall costs associated in the system are minimized.