Mohamed Hamid MEE0845, pp. 81. TEK/avd. för signalbehandling, 2008.
Over the past two decades wireless communication systems have been showing great revolution and rapid growth. Therefore, the standardization agencies together with wireless researchers and industry have been working on new specifications and standards to face the high demand for wireless communication systems.
One of the most critical issues regarding wireless networks regulation agencies and researchers are thinking about is how to manage the available electromagnetic radio spectrum in a way that satisfies the needs of these growing wireless systems both economically and technically especially with the recent crowding in the available spectrum. Hence, building cognitive radio systems support dynamic access to the available spectrum has appeared recently as a novel solution for the wireless system huge expansion.
In this thesis we investigate the MAC layer sensing schemes in cognitive radio networks, where both reactive and proactive sensing are considered. In proactive sensing the adapted and non-adapted sensing periods schemes are also assessed. The assessment of the pre-mentioned sensing schemes has been held via two performance metrics, achieved spectrum utilization factor and idle channel search delay.
The simulation results show that with proactive sensing adapted periods we achieve the best performance but with an observable over head computational tasks to be done by the network nodes which reflects the extent of complexity we need in our network nodes. On the other hand reactive sensing is the simplest sensing schemes with the worst achieved performance.