Resource allocation in multiuser OFDM based cognitive radio systems

Abstract

Over the last decade, the number of wireless applications and subscribers has been growing at an explosive pace due to the distinct characteristics of wireless links. Higher spectrum utilization is needed in order to meet the growing demand for spectrums allocated to wireless devices with a high data rate and diverse quality of service (QoS) requirements. Cognitive radio (CR) is a novel concept for improving the efficiency of spectrum utilization by allowing secondary users (also referred to as CRUs) to access those frequency bands currently unutilized by the primary users (PUs). All CRUs compete to access the limited unlicensed spectrum in a distributed fashion. In order to achieve a good performance, a CRU is required to have the ability to adapt its transmit parameters (e.g. transmit power and channel) dynamically. In this thesis, we address the resource allocation problems in enabling CR networks (CRNs) with the limited available resources to achieve a good performance, which include optimization, dynamical control and game theory.