The Experts below are selected from a list of 37512 Experts worldwide ranked by ideXlab platform
Dmitri Loguinov - One of the best experts on this subject based on the ideXlab platform.
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characterizing tight Link Bandwidth of multi hop paths using probing response curves
International Workshop on Quality of Service, 2010Co-Authors: Seong-ryong Kang, Dmitri LoguinovAbstract:Bandwidth estimation plays an important role in characterizing Internet paths. Existing approaches can be classified into measurement tools [3], [6], [9], [10], [16], [17], [23], [29], which usually have extensive simulations, but no convergence analysis for general cross-traffic, and theoretical models [5], [14], [19], [20], [22], which usually have provable convergence, but no practical implementation. Another issue in related work is the unknown performance of certain proposed algorithms in real networks where delay measurements are not perfect due to various OS and hardware-related timing irregularities [26]. We address the former issue by developing a measurement tool PRC-MT that not only achieves asymptotic accuracy in multi-path networks with arbitrary cross-traffic, but also simultaneously measures the capacity and available Bandwidth of the tight Link. We address the latter issue by performing a comparison study of existing tools in Emulab and assessing their susceptibility to timing irregularities of end-hosts. Our results show that PRC-MT outperforms all existing tools in terms of accuracy, achieves similar convergence delay, and does not require any manual configuration. We also find that interrupt moderation may cause existing tools (such as Pathload [10], Pathchirp [27], and CapProbe [16]) to become quite inaccurate in certain network configurations and exhibit behavior completely different from that in ns2 [28].
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ICDCS - On Estimating Tight-Link Bandwidth Characteristics over Multi-Hop Paths
26th IEEE International Conference on Distributed Computing Systems (ICDCS'06), 1Co-Authors: Seong-ryong Kang, Xiliang Liu, Amit Bhati, Dmitri LoguinovAbstract:In this paper, we explore multi-hop Bandwidth estimation assuming arbitrary cross-traffic at each node and develop a new probing method called Envelope that can asymptotically estimate not only the available Bandwidth but also the raw capacity of the tight Link. Envelope is based on a multi-Link recursive extension of unbiased single-hop estimators proposed in the past (e.g., [14]) and a variation of the packet-cartouche technique [6]. Through extensive simulations, we evaluate Envelope in various network settings and cross-traffic conditions and find that it can measure tight-Link Bandwidth characteristics with accuracy that significantly surpasses that of the existing methods. We also find that Envelope can measure non-tight Links in certain path and cross-traffic configurations.
David Wetherall - One of the best experts on this subject based on the ideXlab platform.
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increasing effective Link Bandwidth by suppressing replicated data
USENIX Annual Technical Conference, 1998Co-Authors: Jonathan Santos, David WetherallAbstract:In the Internet today, transfer rates are often limited by the Bandwidth of a bottleneck Link rather than the computing power available at the ends of the Links. To address this problem, we have utilized inexpensive commodity hardware to design a novel Link layer caching and compression scheme that reduces Bandwidth consumption. Our scheme is motivated by the prevalence of repeated transfers of the same information, as may occur due to HTTP, FTP, and DNS traffic. Unlike existing Link compression schemes, it is able to detect and use the long-range correlation of repeated transfers. It also complements application-level systems that reduce Bandwidth usage, e.g., Web caches, by providing additional protection at a lower level, as well as an alternative in situations where application-level cache deployment is not practical or economic. We make three contributions in this paper. First, to motivate our scheme we show by packet trace analysis that there is significant replication of data at the packet level, mainly due to Web traffic. Second, we present an innovative Link compression protocol well-suited to traffic with such long-range correlation. Third, we demonstrate by experimentation that the availability of inexpensive memory and general-purpose processors in PCs makes our protocol practical and useful at rates exceeding T3 (45 Mbps).
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USENIX Annual Technical Conference - Increasing effective Link Bandwidth by suppressing replicated data
1998Co-Authors: Jonathan R. Santos, David WetherallAbstract:In the Internet today, transfer rates are often limited by the Bandwidth of a bottleneck Link rather than the computing power available at the ends of the Links. To address this problem, we have utilized inexpensive commodity hardware to design a novel Link layer caching and compression scheme that reduces Bandwidth consumption. Our scheme is motivated by the prevalence of repeated transfers of the same information, as may occur due to HTTP, FTP, and DNS traffic. Unlike existing Link compression schemes, it is able to detect and use the long-range correlation of repeated transfers. It also complements application-level systems that reduce Bandwidth usage, e.g., Web caches, by providing additional protection at a lower level, as well as an alternative in situations where application-level cache deployment is not practical or economic. We make three contributions in this paper. First, to motivate our scheme we show by packet trace analysis that there is significant replication of data at the packet level, mainly due to Web traffic. Second, we present an innovative Link compression protocol well-suited to traffic with such long-range correlation. Third, we demonstrate by experimentation that the availability of inexpensive memory and general-purpose processors in PCs makes our protocol practical and useful at rates exceeding T3 (45 Mbps).
Ivan Marsic - One of the best experts on this subject based on the ideXlab platform.
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VTC Fall - Link Quality and Signal-to-Noise Ratio in 802.11 WLAN with Fading: A Time-Series Analysis
IEEE Vehicular Technology Conference, 2006Co-Authors: Jian Zhang, Ivan MarsicAbstract:It is known that for multipath fading channels individual points or average signal-to-noise ratio (SNR) alone do not adequately describe the wireless channel quality. This paper uses time-series modeling to investigate the relationship between SNR and 802.11 Link Bandwidth which we use to define the Link quality. Two models, one linear and another nonlinear, are constructed and fitted to time-series of SNR as input and Link Bandwidth as output. Their performance is measured in terms of the accuracy of prediction of the Link Bandwidth. By the linear Auto- Regressive Moving Average exogenous variables (ARMAX) model, we show the existence of nonlinearity in the input data series, which results in high prediction error. The prediction performance is significantly improved by the nonlinear Echo State Network (ESN) model due to its ability of nonlinear re-expression of the SNR time-series and associating them with the correct Link Bandwidth.
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models for non intrusive estimation of wireless Link Bandwidth
Lecture Notes in Computer Science, 2003Co-Authors: Jian Zhang, Liang Cheng, Ivan MarsicAbstract:Dynamics of Link Bandwidth of a wireless Link, which changes frequently and abruptly due to the dynamic channel sharing, fading, and mobility, is of interest to adaptive network applications and communication protocols. This paper presents a novel approach to estimate wireless Link Bandwidth based on radio signal-to-noise ratio (SNR). Unlike traditional methods that send probe packets, our method is non-intrusive to the wireless network since in IEEE 802.11 wireless local area networks, SNR information is provided by the physical layer for the MAC- and upper layers’ functionality. Theoretical analysis and experimental observation indicate a nonlinear relationship between SNR and the wireless Bandwidth. Based on this, nonlinear models using neural network and Bayesian inference methods are proposed and evaluated on data collected in 802.11b wireless networks. The effectiveness of our method under various environments and scenarios has been studied.
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PWC - Models for Non-intrusive Estimation of Wireless Link Bandwidth
Personal Wireless Communications, 2003Co-Authors: Jian Zhang, Liang Cheng, Ivan MarsicAbstract:Dynamics of Link Bandwidth of a wireless Link, which changes frequently and abruptly due to the dynamic channel sharing, fading, and mobility, is of interest to adaptive network applications and communication protocols. This paper presents a novel approach to estimate wireless Link Bandwidth based on radio signal-to-noise ratio (SNR). Unlike traditional methods that send probe packets, our method is non-intrusive to the wireless network since in IEEE 802.11 wireless local area networks, SNR information is provided by the physical layer for the MAC- and upper layers’ functionality. Theoretical analysis and experimental observation indicate a nonlinear relationship between SNR and the wireless Bandwidth. Based on this, nonlinear models using neural network and Bayesian inference methods are proposed and evaluated on data collected in 802.11b wireless networks. The effectiveness of our method under various environments and scenarios has been studied.
Seong-ryong Kang - One of the best experts on this subject based on the ideXlab platform.
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characterizing tight Link Bandwidth of multi hop paths using probing response curves
International Workshop on Quality of Service, 2010Co-Authors: Seong-ryong Kang, Dmitri LoguinovAbstract:Bandwidth estimation plays an important role in characterizing Internet paths. Existing approaches can be classified into measurement tools [3], [6], [9], [10], [16], [17], [23], [29], which usually have extensive simulations, but no convergence analysis for general cross-traffic, and theoretical models [5], [14], [19], [20], [22], which usually have provable convergence, but no practical implementation. Another issue in related work is the unknown performance of certain proposed algorithms in real networks where delay measurements are not perfect due to various OS and hardware-related timing irregularities [26]. We address the former issue by developing a measurement tool PRC-MT that not only achieves asymptotic accuracy in multi-path networks with arbitrary cross-traffic, but also simultaneously measures the capacity and available Bandwidth of the tight Link. We address the latter issue by performing a comparison study of existing tools in Emulab and assessing their susceptibility to timing irregularities of end-hosts. Our results show that PRC-MT outperforms all existing tools in terms of accuracy, achieves similar convergence delay, and does not require any manual configuration. We also find that interrupt moderation may cause existing tools (such as Pathload [10], Pathchirp [27], and CapProbe [16]) to become quite inaccurate in certain network configurations and exhibit behavior completely different from that in ns2 [28].
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ICDCS - On Estimating Tight-Link Bandwidth Characteristics over Multi-Hop Paths
26th IEEE International Conference on Distributed Computing Systems (ICDCS'06), 1Co-Authors: Seong-ryong Kang, Xiliang Liu, Amit Bhati, Dmitri LoguinovAbstract:In this paper, we explore multi-hop Bandwidth estimation assuming arbitrary cross-traffic at each node and develop a new probing method called Envelope that can asymptotically estimate not only the available Bandwidth but also the raw capacity of the tight Link. Envelope is based on a multi-Link recursive extension of unbiased single-hop estimators proposed in the past (e.g., [14]) and a variation of the packet-cartouche technique [6]. Through extensive simulations, we evaluate Envelope in various network settings and cross-traffic conditions and find that it can measure tight-Link Bandwidth characteristics with accuracy that significantly surpasses that of the existing methods. We also find that Envelope can measure non-tight Links in certain path and cross-traffic configurations.
Jonathan Santos - One of the best experts on this subject based on the ideXlab platform.
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increasing effective Link Bandwidth by suppressing replicated data
USENIX Annual Technical Conference, 1998Co-Authors: Jonathan Santos, David WetherallAbstract:In the Internet today, transfer rates are often limited by the Bandwidth of a bottleneck Link rather than the computing power available at the ends of the Links. To address this problem, we have utilized inexpensive commodity hardware to design a novel Link layer caching and compression scheme that reduces Bandwidth consumption. Our scheme is motivated by the prevalence of repeated transfers of the same information, as may occur due to HTTP, FTP, and DNS traffic. Unlike existing Link compression schemes, it is able to detect and use the long-range correlation of repeated transfers. It also complements application-level systems that reduce Bandwidth usage, e.g., Web caches, by providing additional protection at a lower level, as well as an alternative in situations where application-level cache deployment is not practical or economic. We make three contributions in this paper. First, to motivate our scheme we show by packet trace analysis that there is significant replication of data at the packet level, mainly due to Web traffic. Second, we present an innovative Link compression protocol well-suited to traffic with such long-range correlation. Third, we demonstrate by experimentation that the availability of inexpensive memory and general-purpose processors in PCs makes our protocol practical and useful at rates exceeding T3 (45 Mbps).