Spectrum management is in the core of Internet access and therefore of vital importance for assuring the most important processes of our society. The increasing demand for new services makes the spectrum scarcer and urges national regulatory authorities (NRAs) to promote a more efficient spectrum usage. In this context, dynamic spectrum access (DSA) technologies and the related dynamic spectrum management (DSM) provide new ways of managing spectrum, by dynamically reassigning the underutilized spectrum (i.e. white spaces).This thesis employs a combined approach consisting of agent-based modelling and system dynamics to study spectrum management by means of dynamic neo-institutional economics. Thus, this work combines transaction cost and evolutionary economics into the modelling and analysis of the constantly evolving ICT ecosystem. DSA decreases the costs associated with spectrum transactions and help to clearly define spectrum usage rights, and therefore it provides the basic conditions for the Coasean implications on policy, pushing gradually spectrum management towards a property rights regime.From the analysed scenarios, this thesis shows that indoor deployment is most promising for DSA technologies. Indoor networks transmitting in higher frequency bands require less coordination for achieving mutual benefits from the performed spectrum transactions. Therefore, this thesis emphasizes that spectrum reforms, allowing spectrum transactions, should focus on higher frequency bands and new indoor network deployments, such as smallcells, 5G, IoT and M2M services. NRAs should facilitate flexibility in spectrum assignment in the higher frequency bands, by means of a property rights regime or a flexible licensing regime, to provide indoor deployments with the ability to respond more dynamically to the changes in demand. Moreover, such spectrum reforms may drive spectrum decentralization to stimulate user-centric innovation.Finally, this thesis compares DSA with other alternative mechanisms, such as national roaming and end-user multihoming. The three compared mechanisms may improve the economic efficiency of mobile networks. In indoor networks, while end-user multihoming and national roaming addresses coverage problems, DSA may increase the efficiency further by addressing congestion problems. In outdoor networks, national roaming and end-user multihoming may improve coverage problems.