ITR: Nonlinear Dynamics-Based Robust Congestion Control

虽然互联网起源于计算机和通信技术，但控制和稳定性理论也对其发展产生了重大影响。自1988年Jacobson提出加法增减算法后，第一个有意义的主动队列管理(AQM)算法就是随机早期检测(RED)算法。在RED中，基本思想是通过增加网关处的丢弃概率作为时间平均队列占用率的线性函数来让发送者知道高队列占用率的情况。对部署RED和不部署RED的TCP网络的异常行为进行了现场观测，结果显示负载分批、负载振荡和高参数灵敏度。鉴于互联网的异构性，以及与之相关的参数的广泛变化，扩大参数空间的稳定运行范围显然非常重要。在这项研究计划中，将利用非线性动力系统以及分叉和混沌控制的工具来分析和控制具有一个或多个瓶颈的网络中的拥塞，这些网络具有TCP型和/或UDP(用户数据报协议)类型的业务。该项目强调基本性质的工作，以发展对网络拥塞动态的了解，并解决一些处于拥塞避免和控制问题核心的困难系统问题。该项目建立在PI小组最近在分析TCP-RED和混合交通网络中的非线性动力学方面的工作的基础上。该项目还利用了PI在非线性不稳定控制(分叉控制)和对非线性不确定系统稳定性的闭环监控方面的过去贡献。

Although the internet's origins lie in computer and communication technology, control and stability theory have also had a major influence on its development. After the development of the additive increase, multiplicative decrease algorithm by Jacobson in 1988, the first significant Active Queue Management (AQM) algorithm introduced was Random Early Detection (RED). In RED, the basic idea is to let the senders know about a high queue occupancy situation by increasing the drop probability at the gateways as a linear function of the time-averaged queue occupancy. Field observations of anomalous behavior for TCP networks with and without deployment of RED have been made that show irregular load batching, load oscillations, and high parametric sensitivity. Given the heterogeneity of the internet, and the associated wide variations of parameters, extending the range of stable operation in parameter space is clearly very important. In this research program, tools from nonlinear dynamical systems and from bifurcation and chaos control will be harnessed for the analysis and control of congestion in networks with one or several bottlenecks with TCP-type and/or UDP-type (User Datagram Protocol) traffic. The project emphasizes work of a fundamental nature to develop an understanding of network congestion dynamics and address some of the difficult systems issues that are at the heart of the congestion avoidance and control problem. The project builds on recent work of the PI's group on the analysis of nonlinear dynamics in TCP-RED and mixed traffic networks. The project also leverages past contributions of the PI on control of nonlinear instabilities (bifurcation control) and on closed-loop monitoring of the stability of nonlinear uncertain systems.