In this paper, we introduce and analyze a modified HOL (head-of-the-line) priority scheduling discipline. The modification is incorporated to cope with the so-called starvation problem of regular HOL priority queues. We consider a discrete-time single-server queueing system with two priority queues of infinite capacity and with the introduced priority scheme. We show that the use of probability...

In this paper, an optimistic parallel and distributed logic simulator, XTW, is proposed. In XTW, a new event scheduling mechanism, XEQ, and a new rollback procedure, rb-messages, are proposed for use in optimistic logic simulation. XTW groups LPs into clusters, and makes use of a multi-level queue, XEQ, to schedule events in the cluster. XEQ has an O(1) event scheduling time complexity. Our new...

We study MX/G/1 nonpreemptive and preemptive-resume priority queues with/without vacations under random order of service (ROS) discipline within each class. By considering the conditional waiting times given the states of the system, which an arbitrary message observes upon arrival, we derive the Laplace-Stieltjes transforms of the waiting time distributions and explicitly obtain the first two ...

A new priority queue structure is introduced, for which the amortized time to insert a new element isO(1) while that for the minimumextraction is O(logK). K is the average, taken over all the deleted elements x, of the number of elements that are inserted during the lifespan of x and are still in the heap when x is removed. Several applications of our structure are mentioned.

In a communication network, asymptotic quality of service metrics specify the probability that the delay or buffer occupancy becomes large. An understanding of these metrics is essential for providing worst-case delay guarantees, provisioning buffer sizes in networks, and to estimate the frequency of packet-drops due to buffer overflow. Second, many network control tasks utilize queue length in...

Scheduling algorithms are used in operating systems to optimize the usage of processors. One of the most efficient algorithms for scheduling is Multi-Layer Feedback Queue (MLFQ) algorithm which uses several queues with different quanta. The most important weakness of this method is the inability to define the optimized the number of the queues and quantum of each queue. This weakness has been i...

The Voice over Internet Protocol (VoIP) is a delay sensitive traffic due to real-time applications on networks. The assessment of voice flow quality in the VoIP is an essential requirement for technical and commercial motivation. The packets of VoIP streaming may experience drops because of the competition among the different kinds of traffic flow over the network. A VoIP application is also se...

The analysis of a preemptive priority queuing system with K ( ≥ 2 ) classes of jobs is undertaken. The system consists of a single processor representing a model of discrete dynamic scheduling problems associated with M k / Gk / 1 / ∞ endogenous priority queues. The processor schedules jobs which arrive according to a Markov arrival process. The process of service is arbitrary. With each job ar...

In this paper, we propose a new differentiated service model, referred to as Differentiated Service-EDCA (DS-EDCA), for the Enhanced Distributed Channel Access (EDCA) of IEEE 802.11e wireless local area networks (WLANs). With DS-EDCA, both strict priority and weighted fair service can be provided. The strict priority service is provided for high priority traffic through carefully setting the ED...