Dissertation: On performance analysis of cognitive radios

Along with increasing applications and services of wireless communications, the electromagnetic radio spectrum, a precious natural resource regulated by the government agencies, is becoming more and more scarce.

However, the recent studies by the Federal Communications Commission showed that large portions of the licensed bands remain unused for as much as 85 percent of the time and space. In order to utilize these spectrum more efficiently, cognitive radio has been recognized widely as a potential technology to increase access to spectrum and also make new and improved communication services available to the public.

– I investigate the fundamental problems and develop new radio resource management methods for cognitive radios, for instance, multiple-antenna techniques, optimal power allocation strategies, and system capacity, Duan tells.

– These fundamental research tasks are important for practical use, such as system design, and understanding of this new promising technology.

Different from the traditional wireless communication systems, in cognitive radio networks the interference is caused not only by the secondary users, but also by the primary users. Additionally, the secondary users should not cause unacceptable interference to the primary users.

According to Ruifeng the literature has shown that the fundamental performance of the secondary networks, for instance, ergodic capacity and optimal power allocation strategies, can be much different from the ones of the traditional systems.

The public examination of Ruifeng Duan’s doctoral dissertation ”On Performance Analysis of Cognitive Radios” is on Wednesday 12 February at 12 o´clock in TEK lecture room F651 (Fabriikki). Dr. Uykan Zekeriya (Dokus University, Turkey) will act as an opponent and professor Mohammed Elmusrati as a custos.

Orders of the publication and pdf