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The ieee 802.11 mac-protocol, often used in ad-hoc networks , has the tendency to share the capacity equally amongst the active nodes, irrespective of their loads. An inherent drawback of this fair-sharing policy is that a node that serves as a relay-node for multiple flows is likely to become a bottleneck. This paper proposes a flow-level performance model(More)
This article considers importance sampling as a tool for rare-event simulation. The focus is on estimating the probability of overflow in the downstream queue of a Jacksonian two-node tandem queue; it is known that in this setting “traditional” state-independent importance-sampling distributions perform poorly. We therefore concentrate on(More)
In the planning of modern cellular mobile communication systems, customer behavior has to becarefully taken into account. In this paper, two models dealing with the call retrial phenomenon are presented. The rst model considers a base station with a nite customer population and repeated attempts. A Markov c hain modeling is proposed and a recursive solution(More)
CWI's research has a theme-oriented structure and is grouped into four clusters. Listed below are the names of the clusters and in parentheses their acronyms. ABSTRACT This paper presents a large deviation analysis of the steady-state sojourn time distribution in the GI/G/1 PS queue. Logarithmic estimates are obtained under the assumption of the service(More)
—The main network solutions for supporting QoS rely on traffic policing (conditioning, shaping). In particular, for IP networks the IETF has developed Intserv (individual flows regulated) and Diffserv (only aggregates regulated). The regulator proposed could be based on the (dual) leaky-bucket mechanism. This explains the interest in network element(More)
We consider a queue fed by a mixture of light-tailed and heavy-tailed traffic. The two traffic flows are served in accordance with the generalized processor sharing (GPS) discipline. GPS-based scheduling algorithms, such as weighted fair queueing, have emerged as an important mechanism for achieving service differentiation in integrated networks. We derive(More)