Spectrum Allocation Simulator For Centralized Cognitive Radio Network

Inefficiency in radio spectrum use in traditional wireless communication systems together with the ever increasing spectrum demand from new wireless application services calls for the development of new spectrum allocation policies for wireless communications. The perceived new spectrum allocation policies, which will allow unlicensed users to access the radio spectrum when it is not occupied by licensed users, will be exploited by the cognitive radio technology. A Cognitive Radio can be defined as an intelligent radio which is capable of changing its transmission or reception parameters in accordance to the radio environment and the network state in order to be able to use the available spectrum optimally. Most of today’s wireless networks are characterized by a fixed spectrum assignment policy. With the introduction of the concept of cognitive radio, they are transformed and we talk about cognitive radio networks; which means that the radio frequency can be accessed in a dynamic manner.Implementation of a cognitive radio network will be based on the concept of dynamic spectrum access (DSA) and that it works optimally when a central controller is deployed. For DSA-based cognitive radio networks, multiple access control protocols designed for traditional wireless networks have to be modified to include spectrum sensing and spectrum access. Spectrum sensing required for the estimation of the instantaneous occupancy of the frequency spectrum and is a key enabling factor for Cognitive Radios. Though various techniques exist for performing spectrum sensing, energy detection is preferred whenever there is little or no knowledge of the primary user signal.This thesis’s goal is to produce a simulator for cognitive radio network. The simulator is built in order to show what could happen if unlicensed users were allowed to coexist with licensed users. Therefore, once the simulator is developed, it is used to evaluate the general scenario of cognitive radio networks. From the final tests of the developed simulator, it shows that there exists unused spectrum which was accessed by unlicensed users and that extending this to reality will eradicate the problem of spectrum scarcity.