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The statistical approaches of resource allocation require that input traffic is Gaussian. The Gaussian hypothesis is guaranteed by the central limit theorem (CLT), that is verified when several hundreds of independent flows are multiplexed. In realistic scenarios few flows and long range dependent video traces can be multiplexed, in this case the input traffic can't be considered Gaussian. In this...
This paper proposes an analytical method to evaluate the delay violation probability of traffic flows with statistical quality-of-service (QoS) guarantees in a generalized processor sharing scheduler. The statistical QoS targets, for each service class, are expressed in terms of a delay threshold and delay violation probability. We study both the single node and the end- to-end paths comprising multiple...
Long-range dependence (LRD) is a widely verified property of Internet traffic, which severely impacts network performance yielding longer queuing delays. Moreover, LRD is almost ubiquitous and very hard to remove or control. In this work, we investigated by thorough simulation the effect of schedulers on traffic LRD. We analyzed the output traffic of schedulers merging LRD flows according to various...
Long-range dependence (LRD) is a widely verified property of traffic crossing the wireless LAN radio interface. LRD severely affects network performance yielding longer queuing delays. In this paper, we study how LRD and non-LRD traffic flows influence each other in the IEEE 802.11e wireless access network and their queuing behaviour in downstream schedulers. We consider scenarios with one and two...
Currently, the most advanced framework for stochastic network calculus is the min-plus algebra, providing bounds for the end-to-end delay in networks. The bounds calculated with the min-plus algebra are tight, if compared with previous methods, but we still observe a significant degradation of the tightness of bounds as the number of nodes crossed by flows increases. Moreover, even if the calculations...
The IEEE 802.11e WLAN supports prioritized Quality of Services (QoSs), but it needs additional mechanisms to support also the strict QoS required by real-time services. It has been shown that best performance is achieved when the WLAN is unsaturated. Therefore, a call admission control scheme is required to maintain the WLAN working in the unsaturated case. In this paper, we propose an analytical...
In this paper, we propose an analytical method for the resource allocation and admission control of traffic flows with statistical Quality-of-Service (QoS) guarantees in a Static Priority service discipline. We assume that at the network ingress each traffic flow is controlled by a Token Bucket, and the statistical QoS targets for each service class are expressed in terms of delay bound and delay...
Long-range dependence (LRD) is a largely verified property of Internet traffic, which severely affects queuing performance in network buffers. A common approach for guaranteeing performance requirements is to control the statistical profile of the input traffic by regulators based on the leaky bucket scheme. In this paper, we investigate by simulation how the l/falpha power-law spectrum of LRD traffic...
In this paper, we study the problems of resource allocation and admission control of traffic flows with guaranteed quality of service. Specifically, we deal with traffic flows regulated by dual-leaky buckets and we establish the analytical expressions for (a) the minimum capacity to be allocated in order to guarantee the required delay performance and for (b) the maximum number of flows that is possible...
This paper compares two different approaches for providing QoS in the Internet backbone. The first, denoted as simple approach, is a simple method of Admission Control performed by a weighted-fair-queuing scheduler. This approach guarantees QoS with a suitable overprovisioning of transmission resources. The second approach, denoted as basic statistical approach, is a full-featured statistical framework,...
A linear bounded arrival process (LBAP) traffic regulator is characterized by two parameters, the token rate r and the bucket size b, and the design of such a traffic regulator consists in selecting the most appropriate (r, b) pair according to a performance metric to be optimized. This (r, b) pair is currently selected through a two-step process. Firstly, the LBAP curve of the regulator, formed by...
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