Traffic management in data communication networks plays a significant role in the performance and reliability of the network. It has been shown that the dynamics of TCP-based communication networks can be highly complicated due to TCPs nonlinear Additive Increase Multiplicative Decrease (AIMD) congestion control mechanism and the stochastic behavior of internet traffic. Early works in flow control over TCP/IP networks suggested the deployment of end to end control mechanisms to avoid congestion. However, higher levels of performance and reliability were only achievable via effective cooperation of the intermediate routers in traffic control. Different control strategies have been discussed for homogenous networks. However, less attention has been paid to stability and optimality of the controller for heterogeneous network topologies including multiple time-varying delays for the links. In this work, we propose an optimal controller design scheme for heterogeneous networks preserving the closed-loop system stability. Delay dependent stability conditions of the closed loop system are derived based on the Lyapunov-Krasovskii method. The proposed approach offers flexible choice of control parameters allowing the network administrator to control fairness and response time for each individual node in a network of multiple links with different delay properties. We have also proposed a cross-layer analytical model to estimate Quality of Service (QoS) metrics such as delay, throughput, and jitter in multi-hop wireless ad hoc networks operating on IEEE 802.11-based MAC with CSMA/CA. The proposed model can be used for both evaluating quality of service and designing more efficient model-based control and management schemes. The model is developed in a queuing theory paradigm which investigates the stochastic behavior of data transmission in wireless ad hoc networks. An extensive list of key factors including network layer processing time, network/MAC layer queuing delay, traffic coming from application layer, network layer queuing delay, retransmission delays, random back-off times due to channel contention period, and the time spent for RTS/CTS access method have been considered. The effectiveness of the proposed controller and the model are both analyzed using event-based computer simulations.
|Advisor:||Fekih, Afef, Perkins, Dmitri|
|Commitee:||Bayoumi, Magdy, Madani, Mohammad|
|School:||University of Louisiana at Lafayette|
|School Location:||United States -- Louisiana|
|Source:||DAI-B 76/11(E), Dissertation Abstracts International|
|Keywords:||Feedback control, Network traffic, Queue management, Traffic management|
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