ABSTRACT
In wireless communication services, radio frequency (RF) spectrum is one of the most widely used resources at all times. From cell phones and police scanners to TV sets and garage door openers, all the wireless devices have access to the RF wireless spectrum. Spectrum sharing can be regarded as a system that can share the available RF spectrum between different systems, with certain constraints. Dynamic spectrum access allows unlicensed wireless users (secondary users) to preemptively access the licensed bands when the legacy spectrum holders (primary users) leave the channel. In our work, we study spectrum sharing in Dynamic Spectrum Access Networks (DSAN). This chapter focuses on underlay and overlay spectrum-sharing schemes of continuous-time Markov chains (CTMC) in the hierarchical access model. It explains the multiple secondary users to the scheme and raises the access probability for secondary users to enhance the fairness of the system. The throughput of three secondary users is higher than two secondary users in simulation results.
