WIRELESS COOPERATIVE NETWORKS WITH DIFFERENTIAL MODULATION: PERFORMANCE ANALYSIS AND RESOURCE OPTIMIZATION By WOONG CHO 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 WIRELESS COOPERATIVE NETWORKS WITH DIFFERENTIAL MODULATION: PERFORMANCE ANALYSIS AND RESOURCE OPTIMIZATION By Woong Cho December 2007 Chair: Liuqing Yang Major: Electrical and Computer Engineering In wireless cooperative networks, virtual antenna arrays formed by distributed network nodes can provide cooperative diversity. Obviating channel estimation, differential schemes have long been appreciated in conventional multi-input multi-output (MIMO) communications. However, distributed differential schemes for general cooperative network setups have not been thoroughly investigated. In this dissertation, we develop and analyze distributed differential schemes using two conventional relaying protocols, decode-and-forward (DF) and amplify-and-forward (AF), and space-time coding (STC)-based relaying protocol with an arbitrary number of relays. For each protocol, we analyze the error performance and consider the resource allocation as a two-dimensional optimization problem: energy optimization, location optimization, and joint energy-location optimization. We first derive an upper bound of the error performance for the DF system, the approximated error performance for the AF system, and an upper bound for the STC-based system at reasonably high SNR, respectively. Based on these results, we then develop the energy optimization and relay location optimization schemes that minimize the average system error. Analytical and simulated comparisons confirm that the optimized systems provide considerable improvement over unoptimized ones, and that the minimum error can be achieved via the joint energy-location optimization. We compare the results of optimization and the effects of different relaying protocols and obtain several