| The past decades have witnessed wireless communications traffic exploding. The static spectrum allocation approach can hardly meet the soaring service requirement. Therefore, different spectrum sharing methodologies emerged, such as Authorized Spectrum Access, TV White Space, unlicensed usage, etc. The vast amounts of research work demonstrates that spectrum sharing provides flexibility in spectrum access, increases spectrum usage efficiency, and improves spectrum users utilities.;Despite of these advantages, spectrum sharing has been adopted slowly due in part to the embedded risks. Specifically, each spectrum sharing method leads to different costs, revenue, and Quality of Services (QoS) levels. Based on spectrum users requirement on QoS and profits, they encounter distinct risks. Meanwhile, risks may not necessarily lead to failure. Spectrum users can actively cope with risks through mitigation strategies. Moreover, like any engineering investment, spectrum usage is a decision making process for spectrum users. Different choices are made based on distinct incentives and limitations.;In order to transform spectrum sharing from a radical strategy to commercial reality, it is essential to quantify risks that associate with each spectrum usage method and understand spectrum users decision process. Consequently, this dissertation focuses on determining expected profits, QoS level, risks, and mitigation strategies for each spectrum sharing method, and applying a decision model to analyze spectrum users' choices.;In detail, two types of risks are modeled in this dissertation: (1) QoS risks with respect to throughput, and (2) monetary risks in terms of profits. Specifically, QoS risks are quantified by M/G/C queue. Monetary risks consider costs, revenues, and mitigation strategies. The value of mitigation strategies is determined by the real options approach to reflect the worth of management flexibility. The best spectrum usage method is identified according to decision criteria such as profits maximization and risk minimization.;The merit of this dissertation is two-fold. First, it helps spectrum entrants select the most appropriate spectrum sharing method based on existing spectrum usage environment, potentials of each method, as well as their goals and limitations. Second, it helps regulators, policy makers, and spectrum market understand spectrum entrants' behavior and create interventions in order to obtain favorable outcomes. |
