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Annual conference of Industrial Electronics Society

作者： P. Gil J. Henriques A. Dourado H. Duarte-Ramos Electrical Engineering Department UNL Monte de Caparica Portugal CISUC-Informatics Engineering Department UC-Pólo II Coimbra Portugal

An extended model-based predictive control scheme is proposed and implemented on a bench three-tanks system. This structure is based on a constrained local instantaneous linear model-based predictive controller complemented with a static offset compensator for guaranteeing that tracking errors converge to zero in a finite time. A nonlinear state-space neural network architecture trained offline is used for modelling purposes and forming a seed from where linear models are extracted at each sampling time. Results from experiments show that this extended model-based predictive control (MPC) scheme ensures a good tracking performance with zero steady-state offsets, in spite of modelling errors.

关键词： Predictive models Predictive control Neural networks Sampling methods Steady-state Constraint optimization Industrial control Error correction Linear systems Recurrent neural networks

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A trie-based algorithm for IP lookup problem

A trie-based algorithm for IP lookup problem

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IEEE conference and Exhibition on Global Telecommunications (GLOBECOM)

作者： P.A. Yilmaz A. Belenkiy N. Uzun N. Gogate M. Toy New Jersey Institute of Technology USA Fujitsu Network Communications

The increase in routing table sizes, number of updates, traffic, speed of links and migration to IPv6 have made IP address lookup, based on longest prefix matching, a major bottleneck for high performance routers. We evaluate and compare several schemes based on complexity analysis and simulation results. We present a trie based scheme, which we call linked list cascade addressable trie (LLCAT), which is easy to be implemented in hardware and allows routing table update operations to be performed incrementally requiring very few memory operations guaranteed for worst case to satisfy requirements of dynamic routing tables in high speed routers. We also consider compression schemes to be applied to our algorithm to improve memory consumption and search time.

关键词： Routing internet Telecommunication traffic Traffic control Analytical models Hardware Multimedia systems Bandwidth Optical fiber networks Aggregates

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Differentiated-service-based inter-domain multicast routing: enhancement of MBGP

Differentiated-service-based inter-domain multicast routing:...

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International conference on Computer Communications and networks (ICCCN)

作者： W.M. Moh Liming Xiang Xiang Zhao Eun Park Computer Science Telecm University of Missouri Kansas City MO USA Department of Math. & Ccmputer Sc. San Jose State University Foundation San Jose CA USA Cisco Systems Inc. San Jose CA USA

There has recently been active research on quality of service (QoS) multicasting. Very few, however, address QoS inter-domain multicasting. In this paper, we present a differentiated service (DS) extension to MBGP (Multicasting Border Gateway Protocol), which is an extension of BGP-4 (Border Gateway Protocol 4) to support multicasting. With limited modification to the MBGP, we extend it to support two prospective differentiated service protocols: expedited forwarding (formally premium service) and assured forwarding (formerly assured service). Detailed mechanisms of the DS extension are described. performance is evaluated through extensive simulation of real-network scenarios (including nodes joining/leaving), supporting CBR, VBR, and best-effort traffic flows requesting different classes of service. We believe that the work presented here is significant to the advancement of the next-generation internet supporting DS communications.

关键词： Multicast protocols Quality of service Routing protocols Telecommunication traffic internet High-speed networks Resource management Bidirectional control Proposals Computer science

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TCP enhancement: token based fast-TCP delay algorithm

TCP enhancement: token based fast-TCP delay algorithm

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International conference on Communication Technology (ICCT)

作者： Haitao Wu Jing Wu Keping Long Shiduan Cheng Jian Ma National Key Lab of Switching Technology and Telecommunication Networks Beijing University of Posts and Telecommunications Beijing China Nokia China Research and Development Center Beijing China

TCP is the widely used transport protocol in the internet, and it relies on the end-to-end window-based mechanism to explain the congestion. However, in huge pipe networks, TCP might be ineffective because it starts decreasing its sending rate just after it senses packet loss, implying that the network has already been congested somewhere. Fast-TCP (F-TCP) is an algorithm proposed to improve TCP performance by avoiding congestion. Without modifying TCP itself, F-TCP is readily to be used in intermediate nodes aiming to improve the TCP throughput by suppressing congestion. We enhance this algorithm of F-TCP by using the token-based mechanism. We introduce the F-TCP and then present the token-based algorithm, as well as the simulation results and analysis.

关键词： Delay TCPIP Transport protocols Analytical models Robustness Electronic mail Research and development Throughput control systems Traffic control

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Datagram-transfer protocol for UHF SATCOM

Datagram-transfer protocol for UHF SATCOM

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MILCOM, Military Communications conference

作者： G.R. Huckell E.W. Chandler SPAWAR Systems Center San Diego CA USA Milwaukee School of Engineering Milwaukee WI USA

ISBN: (纸本)0780365216

The joint UHF MILSATCOM Technical Working Group (TWG) is in the process of updating the demand assigned multiple access (DAMA) waveform standards that specify operation over 5-kHz and 25-kHz UHF military satellite channels. While the existing waveform standards have greatly increased the number of communication services supported by UHF SATCOM, the transition from using UHF resources on a dedicated-channel basis to DAMA operation is proceeding very slowly. One factor that has slowed the switch to DAMA operation is that there are many UHF communication requirements that cannot be efficiently supported by the existing waveform standards. The existing standards define protocols primarily for the transmission and reception of serial (streaming) data. However, there is a growing demand for a datagram-transfer protocol capable of supporting a wide variety of protocols at higher layers, including internet protocols. This paper examines distributed and centralized control of datagram transfers and discusses characteristics of typical UHF terminal architectures, such as the red-black interface, that place restrictions on the datagram-transfer protocol. Considering these factors, this paper proposes a data link protocol that provides control over the use of a DAMA time slot, and a network protocol that supports a local area network (LAN) connection to baseband equipments. Incorporation of these protocols into the updated standards would allow new and updated terminals to provide efficient support for a wide variety of higher-layer data connectivity protocols. Finally, this paper provides a discussion of the improved link performance made possible by use of the proposed protocols.

关键词： Communication standards Switches Local area networks Access protocols Military standards Military satellites Communication switching UHF communication internet Centralized control

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Efficient power co-estimation techniques for system-on-chip design

Efficient power co-estimation techniques for system-on-chip ...

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Design, Automation and Test in Europe conference and Exhibition

作者： M. Lajolo A. Raghunathan S. Dey L. Lavagno C&C Research Labs NEC U.S.A. Princeton NJ USA Università di Udine Italy Politecnico di Torino Italy University of California San Diego La Jolla CA USA

We present efficient power estimation techniques for HW/SW System-On-Chip (SOC) designs. Our techniques are based on concurrent and synchronized execution of multiple power estimators that analyze different parts of the SOC (we refer to this as co-estimation), driven by a system-level simulation master. We motivate the need for power co-estimation, and demonstrate that performing independent power estimation for the various system components can lead to significant errors in the power estimates, especially for control-intensive and reactive embedded systems. We observe that the computation time for performing power co-estimation is dominated by: (i) the requirement to analyze/simulate some parts of the system at lower levels of abstraction in order to obtain accurate estimates of timing and switching activity information and (ii) the need to communicate between and synchronize the various simulators. Thus, a naive implementation of power co-estimation may be too inefficient to be used in an iterative design exploration framework. To address this issue, we present several acceleration (speedup) techniques for power co-estimation. The acceleration techniques are energy caching, software power macromodeling, and statistical sampling. Our speedup techniques reduce the workload of the power estimators for the individual SOC components, as well as their communication/synchronization overhead. Experimental results indicate that the use of the proposed acceleration techniques results in significant (8/spl times/ to 87/spl times/) speedups in SOC power estimation time, with minimal impact on accuracy. We also show the utility of our co-estimation tool to explore system-level power tradeoffs for a TCP/IP network interface card sub-system and an automotive controller.

关键词： System-on-a-chip Computational modeling Analytical models Acceleration Independent component analysis control systems Error correction Embedded system Information analysis performance analysis

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Design and evaluation of congestion control algorithms in the future internet

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performance Evaluation Review 1999年第1期27卷 212-213页

作者： Venkitaraman, Narayanan Kim, Tae-Eun Lee, Kang-Won Lu, Songwu Bharghavan, Vaduvur Coordinated Science Laboratory University of Illinois Urbana IL 61801 United States

Linear Increase/Multiplicative Decrease (LIMD) has typically been the congestion control paradigm of choice in the traditional internet with tail-drop routers. In recent years, routers with fair packet dropping policies (e.g. RED) are increasingly being deployed in the internet. In the context of a network with fair packet dropping routers, we challenge the popular notion that Linear Increase/Linear Decrease (LILD) is an unsuitable paradigm for congestion control, and present two key results: (a) LILD is both efficient and fair in the target environment. In fact, LILD outperforms LIMD in most respects. (b) By maintaining the history of transmission rates and loss profiles, congestion control algorithms can effectively distinguish between congestion-induced and non-congestion-induced loss. We present the LILD/H algorithm that combines the above features. LILD/H reacts gently to random/channel probe loss, and aggressively to congestion loss, thereby adapting effectively to the dynamics of the network. Consequently, we believe that LILD/H is a viable congestion control algorithm at the end host or the edge router in the future internet.

关键词： internet Algorithms Communication channels (information theory) Congestion control (communication) Data communication systems Packet networks Random processes Routers Telecommunication traffic Linear increase/linear decrease (LILD) control

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Multi-layer tracing of TCP over a reliable wireless link

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performance Evaluation Review 1999年第1期27卷 144-154页

作者： Ludwig, Reiner Rathonyi, Bela Konrad, Almudena Oden, Kimberly Joseph, Anthony Ericsson Research Herzogenrath Germany Ericsson Mobile Communications AB Lund Sweden Computer Science Division University of California Berkeley CA United States

It is well-known that TCP performance may degrade over paths that include wireless links, where packet losses are often not related to congestion. We examine this problem in the context of the GSM digital cellular network, where the wireless link is protected by a reliable link layer protocol. We propose the use of multi-layer tracing as a powerful methodology to analyze the complex protocol interactions between the layers. Our measurements show that TCP throughput over GSM is mostly ideal and that spurious timeouts are extremely rare. The multi-layer tracing tool we developed allowed us to identify the primary causes of degraded performance: (1) inefficient interactions with TCP/IP header compression, and (2) excessive queuing caused by overbuffered links. We conclude that link layer solutions alone can solve the problem of `TCP over wireless links'. We further argue that it is imperative to deploy active queue management and explicit congestion notification mechanisms in wide-area wireless networks; which we expect will be the bottleneck in a future internet.

关键词： network protocols Cellular radio systems Digital communication systems internet Packet switching Radio links Wide area networks Wireless telecommunication systems Global system for mobile communications (GSM) Transmission control protocol/internet protocol (TCP/IP)

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performance evaluation of HTTP/TCP on asymmetric networks

Performance evaluation of HTTP/TCP on asymmetric networks

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conference on performance and control of network systems iiI

作者： Hasegawa, G Murata, M Miyahara, H Osaka Univ Grad Sch Econ Toyonaka Osaka 5608531 Japan

ISBN: (纸本)0819434345

As the internet users grow, new network technologies are emerging. Those include ADSL and. CATV internet, which essentially provide asymmetric bandwidth for uplink and downlink to the user's connection. In this paper, we investigate the behavior of HTTP/TCP protocols on such asymmetric networks, and present the analytic results of the mean throughput of TCP. The transfer time of Web documents by HTTP over TCP is also derived. In the analysis, we consider newer HTTP/TCP protocols, HTTP/1.1 and TCP Vegas, in addition to HTTP/1.0 and TCP Tahoe. We then investigate the appropriate combination of HTTP and TCP protocols on the asymmetric network. The results show that the effect of HTTP/1.1 is quite small, but TCP Vegas can improve the performance in asymmetric networks if it is appropriately modified as in our proposal.

关键词： HTTP/1.1 TCP Tahoe TCP Vegas asymmetric network ADSL CATV

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Analysis and application of network traffic characteristics to design of high-speed routers

Analysis and application of network traffic characteristics ...

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conference on internet ii - Quality of Service and Future Directions

作者： Ata, S Murata, M Miyahara, H Osaka Univ Dept Informat & Comp Sci Toyonaka Osaka 5608531 Japan

ISBN: (纸本)0819434353

A rapid growth of the internet and proliferation of new multimedia applications lead to demands of high speed and broadband network technologies. Routers are also necessary to follow up the growth of link bandwidths. From this reason, there have been many researches on high speed routers having switching capabilities. To have an expected effect, however, a control parameters set based on traffic characteristics are necessary. In this paper, we analyze the network traffic using the network traffic monitor and investigate the internet traffic characteristics through a statistical analysis. We next show the application of our analytical results to parameter settings of high speed switching routers. Simulation results show that our approach makes highly utilized VC space and high performance in packet processing delay. We also show the effect of flow aggregation on MPLS. From our results, the flow aggregation has a great impact an the performance of MPLS.

关键词： internet traffic measurement log normal distribution flow aggregation MPLS

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