International Journal of Computer Applications (0975 – 8887) Volume 165 – No.9, May 2017 1 A Comparative Study on Different Types of Spectrum Sensing Techniques in Centralized Cognitive Cellular Network Arpita Mandal Heritage Institute of Technology R.C-1/2, Raghunathpur Kolkata-700059 Sabyasachi Chatterjee Heritage Institute of Technology Chowbaga Road, Anandapur PO: East Kolkata, Township, Kolkata- 700-107 ABSTRACT The shortage of spectrum is increasing day by day. To minimize this problem, dynamic spectrum access (DSA) technique is adopted by Cognitive Radio Technology. Spectrum sensing is an important technique of secondary users or cognitive users to scan the spectrum holes or white spaces. In this paper, they have discussed the sensing method in a Centralized Cognitive Cellular Network. They have also performed a hypothesis test for different values of Probability of Successful Detection and Probability of false alarm while operating in the low Signal-to-Noise Ratio. This paper basically explains different types of spectrum sensing methods graphically. From the graphical analysis, it has been observed that matched filter is the best spectrum sensing method with minimum local sensing time and less spectrum sensing error.. Keywords Dynamic Spectrum Access; Spectrum Sensing; Centralized Cognitive Cellular Network; Spectrum Sensing Technique; Matched Filter; Local Sensing Time; Spectrum Sensing Error. 1. INTRODUCTION Radio spectrum is a valuable commodity and it is natural resource of a communication system. Due to the increase in large number of subscriber and wireless services this radio spectrum is getting crowded day by day. The International Telecommunications Union (ITU) on the year 2020 has predicted that for mobile communication system the demand for spectrum is on the order of 1280–1720 MHz [1]. In contrast, the total amount of spectrum currently occupied by mobile communication is around 230–430 MHz, depending on the geographic region [2]. As they know that cellular network is limited by the static allocated of spectrum. However, the real situation with these allocated bands is that most of time these are underutilized with large spectrum holes at different geographic location. To overcome this problem with the means of improved utilization of spectrum, the Defence Advanced Research Projects Agency (DARPA) introduces the dynamic spectrum access (DSA) [3] networking that shifts the communication paradigm from the traditional fixed spectrum access to the Dynamic spectrum access in Cognitive Radio (CR) technology. The cognitive radio concept dates back to 1998 when the idea was first conceived by Sir Joseph Mitola III at the Royal Institute of Technology in Stockholm. Later in 1999 it was presented officially in an article by Joseph Mitola and Gerald Q. Maguire, Jr. To deal with this problem of underutilized spectrum and spectrum allocation congestion cognitive radio approach [4] senses its local spectrum environment, identify the spectrum holes in radio spectrum space to make autonomous decision of spectrum access. Here, they have used the concept of dynamic spectrum access to improve the spectrum utilization efficiency resulting in easier and flexible spectrum access for future wireless network. Cognitive Radio is an enabling technology in which the secondary users are allowed to use the licensed bands without causing interference to the licensed or primary users [5][6][7].There are many steps in the process of spectrum access, such as Spectrum Sensing, spectrum management, spectrum mi-gration and spectrum sharing [8].Cognitive Radio consists of four functional block: Spectrum Sensing. It will sense the presence of spectrum holes in a radio environment. Spectrum Management. It will predict the time for the availability of spectrum holes for the use of cognitive radio user in the absence of primary user. Spectrum Sharing. It will distribute the spectrum holes among the Cognitive Radio user. Spectrum Mi-gration. It will help for the mobility to some better available spectrum. c c Sensing Spectrum Sharing Spectrum Mobility Cognitive Radio Spectrum Sharing Spectrum Mobility Spectrum Management Spectrum Sensing Figure 1: Functional block of Cognitive Radio The primary user will occupy the spectrum band. By the process of spectrum sensing it will sense its environment and if there is any unoccupied spectrum band or vacant spaces which they have called as spectrum holes then secondary user will occupy those spectrum band as long as the primary user will not become active on that band. Spectrum Sensing can be classified into Centralized or Infrastructure-based Cognitive Cellular network and Distributed or Infrastructure-less Cognitive Cellular network. In this paper, they have discussed best possible spectrum sensing technique for centralized cognitive cellular network. The remainder of the paper is organized as follows: Section II explains the channel allocation procedure with computational timing calculation of centralized cellular cognitive radio network. Section III defines mathematical testing model of spectrum sensing scheme. Simulation and graphical analysis is performed in section IV. Section V concludes the paper.