52864471
A binary feedback scheme for congestion avoidance in computer networks
We propose a scheme for congestion avoidance in networks using a connectionless protocol at the network layer. The scheme uses a minimal amount of feedback from the network to the users, who adjust the amount of traffic allowed into the network. The routers in the network detect congestion and set a congestion-indication bit on packets flowing in the forward direction. The congestion indication is communicated back to the users through the transport-level acknowledgment. The scheme is distributed, adapts to the dynamic state of the network, converges to the optimal operating point, is quite simple to implement, and has low overhead. The scheme maintains fairness in service provided to multiple sources. This paper presents the scheme and the analysis that went into the choice of the various decision mechanisms. We also address the performance of the scheme under transient changes in the network and pathological overload conditions.
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.
5318665
Providing rate guarantees to TCP over the ATM GFR service
The ATM guaranteed frame rate (GFR) service is intended for best effort traffic that can benefit from minimum throughput guarantees. Edge devices connecting LANs to an ATM network can use GFR to transport multiple TCP/IP connections over a single GFR VC. These devices would typically multiplex VCs into a single FIFO queue. It has been shown that in general, FIFO queuing is not sufficient to provide rate guarantees, and per-VC queuing with scheduling is needed. We show that under conditions of low buffer allocation, it is possible to control TCP rates with FIFO queuing and buffer management. We present analysis and simulation results on controlling TCP rates by buffer management. We present a buffer management policy that provides loose rate guarantees to SACK TCP sources when the total buffer allocation is low. We study the performance of this buffer management scheme by simulation.
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.
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.
3204907
Performance of Bursty World Wide Web (WWW) Sources over ABR
Bobby Vandalore, Shivkumar Kalyanaraman, Raj Jain, Rohit Goyal, Sonia Fahmy The Ohio State University, Department of CIS Columbus, OH 43210-1277 Phone: 614-688-4482, Fax: 614-292-2911 Email: fvandalor, shivkuma, jain, goyal, fahmyg@cis.ohio-state.edu Seong-Cheol Kim Principal Engineer, Network Research Group, Communication Systems R&D Center Samsung Electronics Co. Ltd., Chung-Ang Newspaper Bldg. 8-2, Karak-Dong, Songpa-Ku, Seoul, Korea 138-160 Email: kimsc@metro.telecom.samsung.co.kr Abstract
15984449
Visual information retrieval
New updated! The latest book from a very famous author finally comes out. Book of visual information retrieval, as an amazing reference becomes what you need to get. What's for is this book? Are you still thinking for what the book is? Well, this is what you probably will get. You should have made proper choices for your better life. Book, as a source that may involve the facts, opinion, literature, religion, and many others are the great friends to join with.
5420102
Dynamic RDT Model for Data Mining
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.
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.
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. >