Many real-life phenomena, such as computer systems, communication networks, manufacturing systems, supermarket checkout lines as well as structural military systems can be represented by means of queueing models. Looking at queueing models, a controller may considerably improve the system’s performance by reducing queue lengths, or increasing the throughput, or diminishing the overhead, whereas...

A load balancing issue for heterogeneous web servers is described in this article. The review of algorithms and solutions is shown. The selected Internet service for on-line echocardiography training is presented. The independence of simultaneous requests for this server is proved. Results of experimental tests are presented.

We consider a K-server threshold-based queueing system with hysteresis, for which a set of forward thresholds (F 1 ; F 2 ; : : : ; F K1) and a set of reverse thresholds (R 1 ; R 2 ; : : : ; R K1) are deened. A simple version of this multi-server queueing system behaves as follows. When a customer arrives to an empty system, it is serviced by a single server. Whenever the number of customers exc...

Wireless communication today supports heterogeneous wireless devices with a number of different wireless network interfaces (WNICs). A large fraction of communication is infrastructure based, so the wireless access points and hotspot servers have become more ubiquitous. Battery lifetime is still a critical issue, with WNICs typically consuming a large fraction of the overall power budget in a m...

With ever increasing Web traac, a distributed multi-server Web site can provide scalability and ex-ibility to cope with growing client demands. Load balancing algorithms to spread the requests across multiple Web servers are crucial to achieve the scalability. Various domain name server (DNS) based schedulers have been proposed in the literature, mainly for multiple homogeneous servers. The pre...