CONTROL TECHNIQUES IN DYNAMIC COMMUNICATION NETWORKS By SANKRITH SUBRAMANIAN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY

of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy CONTROL TECHNIQUES IN DYNAMIC COMMUNICATION NETWORKS By Sankrith Subramanian December 2012 Chair: Warren E. Dixon Cochair: John M. Shea Major: Electrical and Computer Engineering Power control in the Physical Layer of a communication network is used to ensure that each link achieves its target signal-to-interferenceplus-noise ratio (SINR) to effect communication in the reverse link (uplink) of a wireless cellular communication network. In cellular systems using direct-sequence code-division multiple access (CDMA), the SINR depends inversely on the power assigned to the other users in the system, creating a nonlinear control problem. Due to the spreading of bands in CDMA based cellular communication networks, the interference in the system is mitigated. The nonlinearity now arises by the uncertain random phenomena across the radio link, causing detrimental effects to the signal power that is desired at the base station. Mobility of the terminals, along with associated random shadowing and multi-path fading present in the radio link, results in uncertainty in the channel parameters. To quantify these effects, a nonlinear MIMO discrete differential equation is built with the SINR of the radio-link as the state to analyze the behavior of the network. Controllers are designed based on analysis of this networked system, and power updates are obtained from the control law. Analysis is also provided to examine how mobility and the desired SINR regulation range affects the choice of channel update times. Realistic wireless network mobility models are used for simulation and the power control algorithm formulated from the control development is verified on this mobility model for acceptable communication.