Spectrum sensing in cognitive radio - fading, diversity and user cooperation | |
| Author | Herath, Sanjeewa Priyadarshana |
| Call Number | AIT Thesis no.TC-09-02 |
| Subject(s) | Radio--Transmitters and transmission--Fading Cognitive radio networks |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Telecommunications, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-09-02 |
| Abstract | The cognitive radio system is a mechanism which allows unlicensed (cognitive) user to utilized free bands. Cognitive users detect the presence of such free bands and energy detection is highly regarded as prospective technique for this spectrum sensing task. In this research, first, we quantify the energy detector performance vari¬ation over inherent fast fading effects with Nakagami-m, Rician and Rayleigh channel models. To overcome the mathematical difficulties faced in traditional probability density function based method and to evaluate the related Marcum-Q integrals, a new technique is developed which is based on contour integral representation and moment generating function (MGF) of output signal-to-noise ratio (SNR). To overcome fading effects and to benefit from multipath propagation, maximal ratio, equal gain, selection, switch-and-stay, square-law and square-law selection diversity combining schemes are analyzed. In this exercise, use of the newly introduced MGF based approach and al¬ternative series representations of Marcum-Q function to overcome the mathematical difficulties is shown. In order to improve the detection in the low SNR regions, a new cooperative scheme based on primary and cognitive user collaboration is developed. This method is based on first cognitive radio network standard IEEE 802.22 and ben¬efits from primary user dynamic resource allocation. This system architecture utilizes a convex optimization approach and can co-exist with proposed (in previous research studies) interference temperature constrained systems. By means of a combination of gains achieved by receiver diversity techniques, cognitive and primary user cooperative sensing scheme (proposed in this research study) and cognitive user cooperative sensing schemes (proposed in previous research studies), detection reliability under fading is significantly improved. |
| Year | 2009 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-09-02 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Rajatheva, R. M. A. P. |
| Examination Committee(s) | Ahmed, Kazi M.;Poompat Saengudomlert |
| Scholarship Donor(s) | The Government of Finland |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2009 |