Mohammad Sadeghian Kerdabadi - Ph.D. Student, Department of Electrical and Computer Engineering, University of Birjand, Birjand, Iran
Reza Ghazizadeh - Assistant Professor, Department of Electrical and Computer Engineering, University of Birjand, Birjand, Iran.
Hamid Farrokhi - Assistant Professor, Department of Electrical and Computer Engineering, University of Birjand, Birjand, Iran

Cognitive radio networks (CRNs) have been proposed as a promising solution for spectrum scarcity problem and inefficient spectrum management by means of dynamic spectrum access. The CR technology allows unlicensed users to access licensed spectrum bands. Since licensed users have priorities to use the bands, the unlicensed users need to continuously monitor the licensed users’ activities to avoid the interference and collisions. This paper focuses on spectrum sensing in CR which is a recently introduced technology in order to improve the spectrum efficiency. Increasing efficiency of the spectrum usage is an urgent need as an intrinsic result of the increasing demand for higher data rates, better quality of services and higher capacity. There are several spectrum sensing techniques proposed in literature for cognitive radio based systems like Non cooperative and cooperative spectrum sensing. In this paper, energy detection based spectrum sensing systems for cognitive radios with and without multiple antenna are examined and comparative performance results are obtained in wireless communication channels. We consider three multiple antenna processing methods and analyze their detection performance based on the achieved probability of detection for a pre-specified probability of false alarm and given signal-to-noise ratio

Cognitive radio Network, Spectrum sensing, Cooperative sensing, Energy detection, Maximum ratio combining