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Full Duplex Communication in Cognitive Radio Networks

Student thesis: Doctoral ThesisDoctor of Philosophy

Over the past decade mobile services have evolved from basic voice communication to mobile-broadband multimedia services and sophisticated wireless applications. Today, we cannot imagine a world without wireless communications and smart mobile devices. Any wireless communication relies on the availability of radiofrequency spectrum, which is inherently a finite resource and cannot be produced. This unprecedented growth of wireless devices and services has motivated academia and industry to look for new solutions in utilizing the wireless spectrum more intelligently and efficiently. Cognitive radio (CR) and Full Duplex (FD) communication are two promising technologies recently developed to enhance spectrum utilization and network efficiency, and combination thereof will improve the performance even further. CR technology has been extensively studied within the past 15 years and made available for commercial applications. On the other hand, full duplex communication was not deemed possible due to some complications until recently, when the advances in Self-Interference Suppression (SIS) methods made it possible to implement this technology in future wireless networks.
In line with the global attention on full duplex and cognitive radio technologies, this research investigates new schemes of implementing full duplex communication in cognitive radio networks. In part of this thesis, the advantages of in-band full duplex transmissions in doubling the spectral efficiency and enhancing overall performance of a system, have been studied in a proposed scheme incorporating cooperative Automatic Repeat reQuest (ARQ) in an overlay cognitive radio network. It is shown that a full duplex cooperative ARQ protocol will increase the throughput of primary and secondary networks, without any degradation on primary network performance.
Another part of this thesis focuses on asynchronous bidirectional FD communication in a CR system. While detection probability is enhanced due to
cooperative sensing, the probability of collision and average duration of collisions are decreased significantly thanks to the implementation of asynchronous full duplex transmissions. These gains in network performance are additional to improved throughput of secondary network achieved through implementation of full duplex transmission. The proposed schemes are mathematically analyzed and have been numerically verified through extensive simulations.
As a contribution to IEEE 802.22 Standard revision, a novel suggestion incorporating the use of directional sector antennas, and full duplex operation of secondary users in a Wireless Regional Area Network (WRAN) has been proposed in another part of this thesis and it has been shown how research achievements may be implemented in practice.
A summary of the thesis plus some suggestions for future work conclude this thesis.
Original languageEnglish
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Award date2017

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