ITR: Nonlinear Dynamics-Based Robust Congestion Control

虽然互联网起源于计算机和通信技术，但控制和稳定理论也对其发展产生了重大影响。继Jacobson于1988年提出加性增乘性减算法之后，第一个重要的主动队列管理（AQM）算法是随机早期检测（RED）。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的线性函数），让发送方知道高队列占用情况。对TCP网络的异常行为进行了现场观察，发现有和没有部署RED的TCP网络显示出不规则的负载批处理、负载振荡和高参数灵敏度。鉴于互联网的异质性，以及相关参数的广泛变化，在参数空间中扩展稳定运行的范围显然是非常重要的。在本研究计划中，将利用非线性动态系统和分岔和混沌控制的工具来分析和控制具有tcp类型和/或udp类型（用户数据报协议）流量的一个或几个瓶颈的网络中的拥塞。该项目强调基本性质的工作，以发展对网络拥塞动态的理解，并解决一些困难的系统问题，这些问题是拥塞避免和控制问题的核心。该项目建立在PI小组最近对TCP-RED和混合交通网络的非线性动力学分析的基础上。该项目还利用PI过去在非线性不稳定性控制（分岔控制）和非线性不确定系统稳定性的闭环监测方面的贡献。

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.