Analysis And Synthesis Of Complex Networked System

This paper addresses the problem of congestion control for network and networked control system. Time delay is an inherent property of networked control system. Firstly, the self-similar degree of network-induced time delay is checked by computing Hurst parameter based on R/S, variance and wavelet analysis method respectively, and existence of self-similarity is verified by the above analysis results. Secondly, the largest lyapunov exponent of network-induced time delay is computed based on the improved small-data method and used to identify the chaos of time delay, the results show that chaos in time delay do exist. Thirdly, a Semi-Markov Model is proposes to characterize network-induced time delay, a method to computing delay distribution and state transition matrix is presented based on statistics analysis. The problem of robust stabilization for networked control systems with uncertainty both in mode and state transition matrix delay is discussed based on Markovian jump linear system theory, and some conditions of robust exponential stability are obtained.An approach to forecast time delay is put forward based on WDR (wavelet decomposition and reconstruction) and RBF(radial basis function) neural network, the forecast accuracy of the proposed method is effectively improved compared with the general forecasting approaches. Based on the delay prediction results, a novel variable- horizon adaptive Generalized Predictive Control (GPC) control scheme for NCS is presented, which extends the GPC algorithm to compensate for network-induced time delay. The simulation results show that the method put forward in this paper is effective. Congestion control plays a crucial role on the success of the modern Internet. Firstly, we present an improved model of network fluid flow in this chapter, which is applied in the design of PID congestion control algorithm, and the parameter regions of the robust stability can be determined by using a graphical approach.Recently, wireless access to networks, especially to the Internet, has received significant attention with development of heterogeneous wireless technologies. In this paper, We study a kind of heterogeneous network in which the backbone is a traditional wired network supporting Internet TCP, while end user access is via wireless. RED, PID and PI are respectively developed, from control-theoretic viewpoint, to the design of an active queue management (AQM) based congestion control algorithm for the heterogeneous network. Finally, the proposed three approached is applied to the congestion control algorithm design of heterogeneous network, and yieldes an effective and systematic way for the design problem. Simulation results are provided to illustrate the design procedure and the effectiveness of the proposed methodes.