Dynamic spectrum allocation in multiuser wireless networks

Today´s wireless networks are characterized by a fixed spectrum assignment policy. With ever increasing demand for frequency spectrum, there is need to make a paradigm shift and consider allowing more numbers of unlicensed users to transmit their signals in the licensed bands. New approaches of efficient spectrum sharing techniques with unlicensed users are called for; one of them being Cognitive Radios (CRs). Other main functions of CRs that form major steps of the spectrum management process are spectrum sensing, spectrum decision, and spectrum mobility. This work underpins spectrum sensing techniques that can lead to an increase in the efficient use of spectrum by allowing opportunistic unlicensed temporary access to the unused frequency bands across the licensed radio spectrum-dynamic spectrum access. Dynamic spectrum access is viewed with significant potential as an enabler to realizing efficient spectrum utilization. The need to adopt a dynamic spectrum licensing policy is clearly vital.