16881430
Multimedia Satellite Networks and TCP/IP Traffic Transport
Abstract To meet an increasing demand for multimedia services and electronic connectivity across the world, satellite networks will play an indispensable role in the deployment of global networks. A number of satellite communication systems have been proposed using geosynchronous (GEO) satellites, medium earth orbit (MEO) and low earth orbit (LEO) constellations operating in the Ka-band and above. At these frequencies, satellite networks are able to provide broadband services requiring wider bandwidth than the current services at C or Ku-band. Most of the next-generation broadband satellite systems will use ATM or "ATM-like" switching with onboard processing to provide full two-way services to and from earth stations. The new services gaining momentum include mobile services, private intranets, and high-data-rate internet access carried over integrated satellite-fiber networks. Several performance issues need to be addressed before a transport layer protocol like TCP can satisfactorily work over satellite ATM for large delay-bandwidth networks. The authors review the proposed satellite systems and discuss challenges such as traffic management and QoS requirements for broadband satellite ATM networks. The performance results of TCP enhancements for Unspecified Bit Rate over ATM (ATM-UBR+) for large bandwidth-delay environments with various end system policies and drop policies for several buffer sizes are presented.
3236747
Use-it-or-lose-it Policies for the Available Bit Rate (ABR) Service in ATM Networks
Abstract The Available Bit Rate (ABR) service has been developed to support data applications over Asynchronous Transfer Mode (ATM). The ABR service uses a closed-loop rate-based traffic management framework where the network divides left-over bandwidth among contending sources. The ATM Forum traffic management group also incorporated open-loop control capabilities to make the ABR service robust to temporary network failures and source inactivity. An important problem addressed was whether rate allocations of sources should be taken away if sources do not use them. The proposed solutions, popularly known as the Use-It-or-Lose-It (UILI) policies, have had significant impact on the ABR service capabilities. In this paper we discuss the design, development, and the final shape of these policies and their impact on the ABR service. We compare the various alternatives through a performance evaluation.
789958
Myths about Congestion Management in High Speed Networks
Weaknesses in several recently proposed ideas about congestion control and avoidance in high-speed netwroks are identified. Both sides of the debate concerning prior reservation of resources versus walk-in service, open-loop control versus feedback control, rate control versus window control, and router-based control versus source-based control are presented. The circumstances under which backpressure is useful or not are discussed, and it is argued that a single congestion scheme is not sufficient, but that a combination of several schemes is required for complete congestion management in a network.
3264607
Congestion Control in Computer Networks: Trends and Issues
Myths about congestion control are examined, and an explanation of why the trend toward cheaper memory, higher-speed links, and higher-speed processors has intensified the need to solve the congestion problem is provided. A number of proposed solutions are described, and a classification of congestion problems as well as their solutions is presented. The reasons why the problem is so difficult are identified, and the protocol design decisions that affect the design of a congestion control scheme are discussed. The author's recent proposals, namely, timeout-based congestion control, a DECbit scheme and a delay-based scheme for congestion avoidance are described, and areas for future research are suggested. >
609563
A definition of general weighted fairness and its support in explicit rate switch algorithms
We give a general definition of weighted fairness and discuss how a pricing policy can be mapped to general weighted (GW) fairness. The GW fairness can be achieved by calculating the excess fairshare (weighted fairshare of the left over bandwidth) for each VC. We show how a switch algorithm can be modified to support the GW fairness by using the excess fairshare term. We use ERICA+ as an example switch algorithm and show how it can be modified to achieve the general fairness. Simulations results are presented to demonstrate that, the modified switch algorithm achieves GW fairness. An analytical proof for convergence of the modified ERICA+ algorithm is given in the appendix.
16677800
AQuaFWiN: adaptive QoS framework for multimedia in wireless networks and its comparison with other QoS frameworks
In a wireless environment, due to topology changes and characteristics of media (interference in radio signals) the bandwidth of a link is unpredictable and possibly very low, the error rates are variable and extremely high. Provisioning and guaranteeing quality of service (QoS) in such an environment is a very challenging problem. In this paper we propose an adaptive and QoS framework to support multimedia applications in a wireless networking environment. The proposed framework is hierarchical in nature with cluster of mobile end hosts connected to a base station, base stations are connected to a supervisory node, which in turn is connected to the wired infrastructure. The changing conditions in wireless due to interference and possibly mobility, entitle that the real-time applications needing stringent QoS should be adaptable. The framework uses a generic feedback mechanism to support adaptability at all layers of the wireless network. An overview of existing wireless architectures which support QoS is given. The architectures discussed are WAMIS (wireless adaptive multimedia information system), SWAN (seamless wireless ATM network), MMWN (multimedia support for mobile wireless networks), and QGMC (QoS guarantees in mobile computing). The proposed approach is compared with these existing methods.
38848848
Rough Set Based Decision Tree Model for Classification
Decision tree, a commonly used classification model, is constructed recursively following a top down approach (from the general concepts to particular examples) by repeatedly splitting the training data set. ID3 is a greedy algorithm that considers one attribute at a time for splitting at a node. In C4.5, all attributes, barring the nominal attributes used at the parent nodes, are retained for further computation. This leads to extra overheads of memory and computational efforts. Rough Set theory (RS) simplifies the search for dominant attributes in the information systems. In this paper, Rough set based Decision Tree (RDT) model combining the RS tools with classical DT capabilities, is proposed to address the issue of computational overheads. The experiments compare the performance of RDT with RS approach and ID3 algorithm. The performance of RDT over RS approach is observed better in accuracy and rule complexity while RDT and ID3 are comparable.
39032710
Refining decision tree classifiers using rough set tools
The proposed hybridized rough set framework is composed of traditional Rough Set (RS) approach and classical Decision Tree (DT) induction algorithm. RS helps to identify dominant attributes and DT algorithm results in simpler and generalized classifier. The implementation of the Hybridized Rough Set Framework is presented as the RDT algorithm. GA heuristics are used to generalize the RDT algorithm further. Experimental results obtained on applying the hybridized rough set framework and the related base algorithms on datasets belonging to the three categories are presented in this paper. Accuracy, complexity, number of rules and number of attributes in the induced classifier assess the performance of the candidate algorithms. The results indicate that the proposed framework is an effective model for classification.
47572575
The Art of Computer Systems Performance Analysis
the art of computer systems performance analysis by is one of the most effective vendor publications worldwide? Have you had it? Not at all? Ridiculous of you. Currently, you can get this impressive book simply here. Locate them is layout of ppt, kindle, pdf, word, txt, rar, as well as zip. Just how? Merely download and even read online in this site. Now, never ever late to read this the art of computer systems performance analysis. Whatever our proffesion, the art of computer systems performance analysis can be good source for reading. Find the existing reports of word, txt, kindle, ppt, zip, pdf, and also rar in this website. You can absolutely read online or download this book by right here. Currently, never miss it. Our goal is always to offer you an assortment of cost-free ebooks too as aid resolve your troubles. We have got a considerable collection of totally free of expense Book for people from every single stroll of life. We have got tried our finest to gather a sizable library of preferred cost-free as well as paid files. GO TO THE TECHNICAL WRITING FOR AN EXPANDED TYPE OF THIS THE ART OF COMPUTER SYSTEMS PERFORMANCE ANALYSIS, ALONG WITH A CORRECTLY FORMATTED VERSION OF THE INSTANCE MANUAL PAGE ABOVE.
40775308
Vector Field Analysis for Oriented Patterns
Presents a method, based on the properties of vector fields, for the estimation of a set of symbolic descriptors (node, saddle, star-node, improper-node, center, and spiral) from linear orientation fields. Planar first-order phase portraits are used to model the linear orientation fields. A weighted linear estimator is developed to estimate linear phase portraits, using only the flow orientation. A classification scheme for planar first-order phase portraits, based on their local properties: curl, divergence, and deformation is developed. The authors present results of experiments on noise-added synthetic flow patterns and real oriented textures. >
7565598
Towards coarse-grained mobile QoS
Supporting Quality of Service is an important objective for future mobile and wireless systems, and requires resource reservation and admission control to achieve. In this paper, we introduce a novel coarse grained approach to admission control termed Virtual Bottleneck Cell. Our approach is designed to scale to many users and handoffs, while simultaneously controlling “hot spots” and system bottlenecks. The key technique is to hierarchically control the virtual system, ensuring QoS objectives are satisfied without requiring models or accurate predictions of the users’ future locations. We develop a simple analytical model to study the system and illustrate several key components of the approach. Finally, we perform simulations in a two-dimensional network to compare the performance obtained with Virtual Bottleneck Cell with alternate schemes, including the optimal off line algorithm.