Control-Theoretic Methods for the Analysis and Design of High-Speed Networks

点击翻译按钮获取中文摘要

Control-Theoretic Methods for the Analysis and Design ofHigh-Speed NetworksCarolyn Beck and R. SrikantOver the last few years, a significant amount of research activity in networking has been devoted to thestudy of congestion control in the Internet. New algorithms have been suggested for congestion controllersat the sources and active queue management at the routers. While the success of the mathematical modellingapproach to congestion control has been quite remarkable, many important problems remain open. In thisproposal, we have targeted a few of these problems which have a control-theoretic flavor and therefore, webelieve, would benefit from analysis using linear or nonlinear system-theoretic methods.The practical impact of the proposed research would be the development of algorithms which will resultin a loss-free, delay-free Internet, thus enabling the users of the Internet to enjoy levels of quality of ser-vicethat are not seen today. Further, our work will lay the groundwork for future Internet algorithms whenthe access speeds are expected to grow by several orders of magnitude as compared to today's networks.Scalable algorithms for high-speed networks are already under development; however, these schemes pri-marilyaddress the fact that today's TCP is not scalably stable. On the other hand, our work will not onlyaddress scalable stability, it also aims to improve the quality of service seen by Internet users by essentiallyeliminating queueing delays and large buffer build-ups which lead to packet losses.Intellectual Merit Our recent work has established scalable local stability of a class of congestion man-agementalgorithms for the Internet with a fixed number of sources, and robustness of these algorithms in thespecial case of a link accessed by many sources. While we have only scratched the surface of this rich classof problems, the appealing features, such as distributed implementation, robustness, full network utilization,etc., observed in the preliminary work indeed ask for a more comprehensive study of the underlying issuesin a broader context. Specifically, we would like to know whether we can establish the global stability ofthese algorithms for general topology networks, quantify their robustness to worst-case disturbance as wellas stochastic disturbances, and study their stability properties when there are source arrivals and departures.In the process, we plan to appeal to the rich literature on model reduction for large-scale control systems.Broad Impact One of the PIs teaches a graduate course on Modeling and Control of High-Speed Networks(ECE 459). The results from this project will be incorporated into that course. We have prior experiencewith employing undergraduates to work on research projects in the area of network design and control.If this project is funded, we will continue to do the same. The algorithms developed as a result of thisproject will be implemented in Internet lab, housed in the Coordinated Science lab and directed by one ofthe PIs. Over the past four years, we have advised six graduate students and two post-doctoral researchassociates from under-represented groups in engineering. We will continue our efforts to recruit studentsfrom under-represented groups for graduate studies. One of the PIs teaches undergraduate courses in theDepartment of General Engineering. Traditionally, this department has a high percentage of women in theundergraduate population compared to other engineering departments. By incorporating some of the resultsof this project in the undergraduate courses in General Engineering, we hope to stimulate interest in thisarea among students from this group.P-1