IJISET - International Journal of Innovative Science, Engineering & Technology, Vol. 3 Issue 4, April 2016. www.ijiset.com ISSN 2348 – 7968 “Review On: Spectrum Sensing in Cognitive Radio Using Multiple Antenna” Komal Pawar 1 , Dr. Tanuja Dhope 2 1 P.G. Student, Department of Electronics and Telecommunication, GHRCEM, Pune, Maharashtra, India 2 Associate Professor, Department of Electronics and Telecommunication, GHRCEM, Pune, Maharashtra, India Abstract As the deployment of new wireless devices and applications is growing rapidly there is an increase in demand for wireless radio spectrum. Researchers show that more than 70% of available spectrum is not used efficiently. For efficient utilization of spectrum we need to know whether the spectrum is used by primary user or not which is called Spectrum Sensing. The concept Cognitive Radio is proposed to address the issue of spectrum efficiency. In this paper, we consider various spectrum sensing techniques using multiple antennas. Multiple antenna technique for wireless communication provide better transmission with higher data rates. Simulations show Pd Vs Pfa and Pmd Vs Pfa Keywords: Cognitive Radio, Spectrum sensing, Spectrum sensing Techniques, Energy Detection, Multiple antennas. 1. Introduction Due to the rapid growth of wireless communications, more and more spectrum resources are needed. Most of the spectrum bands are exclusively allocated to specific licensed services. However, a lot of licensed bands, such as those for TV broadcasting, are underutilized, resulting in spectrum wastage. This has promoted Federal Communications Commission (FCC) to open the licensed bands to unlicensed users through the use of cognitive radio (CR) technology. There have been many factors that have lead to development of cognitive radio technology. One of the major factor is utilization of radio spectrum. Cognitive Radio senses the operating environment, learn and adapt in real time according to environment. The primary objectives of CR is to provide reliable communication and to utilize radio spectrum efficiently. The term "Cognitive Radio" was coined by Joseph Mitola in 2002. In this paper, we use the definition adopted by Federal Communications Commission (FCC): “Cognitive radio: A radio or system that senses its operational electromagnetic environment and can dynamically and autonomously adjust its radio operating parameters to modify system operation, such as maximize throughput, mitigate interference, facilitate interoperability, access secondary markets.” The main challenge to the Cognitive radios is the spectrum sensing. We need spectrum sensing techniques for sensing the radio environment. There are three types of spectrum sensing techniques: energy detection, matched filter detection, and cyclostationary feature detection. These techniques have some limitations. Energy detection approach shows poor performance under low SNR conditions and cannot differentiate the interference from other secondary user sharing the same channel. Matched filter detection use is limited as there is hardly any information of primary user signal available at secondary user. These methods have various advantages but they also have some limitations. In order to address problems related to spectrum sensing in CR, a new concept of MIMO technology is introduced in Cognitive Radio. This technique increases the spectral efficiency leading to improvement in the system performance. Here, multiple antennas are placed both on primary user as well as secondary user to increase the probability of sensing a target. MIMO technology is an efficient way to achieve the goal of reliable and accurate spectrum sensing. Dynamic spectrum allocation and sharing schemes are required to fully utilize the spectrum resources. There have been rapid growth in past few years on Cognitive Radios. Cognitive Radio Technology provides future wireless devices with additional bandwidth, reliable communication and versatility for rapidly growing data applications. Recently, many signal processing techniques have been developed for spectrum sensing, and these can be classified as either non cooperative detection or cooperative detection. One of the first examples of a widely manufactured and distributed cognitive radio system is found in the cellular telecommunications arena. There are a lot of progresses on CR technology in the last ten years. 313