2017 2 nd International Electrical Engineering Conference (IEEC 2017) May 19 th -20 th , 2017 at IEP Centre, Karachi, Pakistan 1 I. INTRODUCTION With the need of radio applications, the accessibility of radio spectrum is becoming additional expensive. Few unlicensed band were left to open for future use but with the rapid development in personal wireless technology these bands are now congested. Cognitive Radio (CR) is a self-maintaining process without any human involvement, was first proposed by Joseph Mitola III and Gerald Q. Maguire, Jr [1]. After the introduction of CR, it has been adopted by spectrum regulatory authorities such as FCC. Many researchers and research academics contributed in CR and related projects. They started to find the methods to share the spectrum. There are two models of spectrum sharing [3]: Owned - The spectrum is handover to service providers after the auction of spectrum. Common - After the agreement upon etiquette the spectrum can be used. The conventional (owned) method is being implemented but it is still insufficient. As the allocation of spectrum to each wireless application is fixed, so it will be difficult for new and existing wireless technology to be allocated in new band. The OSA (opportunistic spectrum access) and DSA (dynamic spectrum access) methods are being focused by researchers. This problem of fixed allocation has urged authorities to find any method where secondary user (SU) efficiently utilizes the spectrum gap in primary user (PU) licensed spectrum band. In 2003, FCC organized the group for working in CR. In 2004, the access of white space in TV broadcast band is allowed by FCC. Defense Advanced Research Product Agency (DARPA) sponsored Next Generation program in which Filtered Multi-Tone (FMT) CR system is proposed [9]. After research and development in the field of CR, still strong coordination is required between authorities and research academia. On the other hand, IEEE standardized as 802.22, started the group working on TV spectrum and made the access to the secondary system [4]. One of the natural forms of CR is that the secondary user is equipped with the capability of spectrum sensing. Cognitive Radio is supported by dynamic spectrum access, which selects ideal free channel. After selecting the channel, other functionalities are required for adapting available spectrum [5]. Cognitive radio has some specific functionalities, which have been presented as follows; Spectrum Sensing: The purpose of this function to detect the white space or spectrum gap and share to secondary user without any disturbance to primary channel. Spectrum Management: Finding the ideal free channel according to the need of user. Spectrum Mobility: Provides consistent communication by handover to better spectrum channel. Spectrum Sharing: There are number of secondary Realization of Spectrum Sensing in Cognitive Radio Yasir Iqbal 1* , Yusra Kaleem 2 , Ayesha Asad 3 and Muhammad Waseem 4 1 Department of Telecommunication Engineering, Sir Syed University of Engineering and Technology, Karachi, 75300, Pakistan (yasiriqbal.engr@gmail.com) * Corresponding author 2 Department of Telecommunication Engineering, Sir Syed University of Engineering and Technology, Karachi, 75300, Pakistan (yusra.kaleem13@gmail.com) 3 Department of Telecommunication Engineering, Sir Syed University of Engineering and Technology, Karachi, 75300, Pakistan (electro-ayesha@hotmail.com) 4 Department of Telecommunication Engineering, Sir Syed University of Engineering and Technology, Karachi, 75300, Pakistan (engrmwaseem@gmail.com) Abstract: The radio spectrum is becoming increasingly rare. The demand and needs of new wireless applications are escalating dramatically; likewise, the bands less than 3 GHz are extremely sparse. Radio spectrum has become bottleneck that could obstruct the new wireless communication system. According to the survey conducted by Federal Communication Commission (FCC), a huge number of bands are underutilized, ranging from 15 to 85%, while few bands are overloaded. Therefore, the concept of Cognitive Radio was developed to overcome the problem of low spectrum utilization and to solve the spectrum congestion problem effectively. The implementation of Cognitive Radio assures the full utilization of spectrum for secondary user, when the primary (licensed) user is not available. Spectrum sensing is a function of Cognitive Radio, which primarily is responsible to sense and analyze its spectrum environment, then it detects unused spectrum in licensed band. This paper demonstrates Energy Detection technique of spectrum sensing which requires no previous knowledge of received signal. Energy Detection algorithm is implemented on Raspberry pi through MATLAB 2014 to analyze the cognitive radio network. Keywords: Cognitive Radio, Energy Detection, PSD, Spectrum Sensing, Channel Utilization, Raspberry pi.