International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue4- April 2013 ISSN: 2231-5381 http://www.ijettjournal.org Page 880 Cognitive Radio in Public Safety and Emergency Applications Yasaswi Kolluru # , Rayala Ravi Kumar * # Final Year B.Tech, Dept. of ECE, KL University, Vaddeswaram, AP, India * Associate Professor B.Tech, Dept. of ECE, KL University, Vaddeswaram, AP, India Address Abstract— During disaster and emergency conditions traditional communication facilities get impaired but it is important to have communication between all the first responders. In such situations wireless technologies offer a suitable way for communication. The emergency communications and disaster relief works create high traffic load and which in turn leads to congestion also network capacity and coverage are the major drawbacks of traditional wireless technologies. As it is known that the spectrum is partitioned and allocated for different purposes, not all the spectrum is used in particular space or time and the unused spectrum can serve the demand in need. “Cognitive radio” which is an intelligent wireless communication system can find spectrum holes (unused spectrum bands) and uses them for communication there by facilitating the effective use of spectrum. So this paper discusses the application of cognitive radio as a solution for communication in Public Safety services and Emergency Communications. Keywords— Cognitive Radio, Ad hoc Network Architecture, Emergency Communications, Network Coverage Extension. I. INTRODUCTION Cognitive radio can be considered as a key technology for future wireless communications. There are diverse wireless technologies that support Internet access and other traffic services, these different wireless networks/systems can be integrated and any one of them can be used appropriately based on the communication environments and application requirements. This integration can be made through cognitive radio which is a new model in wireless communications that ensure better services for public safety, emergency and military etc. Cognitive Radio improves the spectrum utilization and hence when there is congestion or failure of certain existing technologies at times of emergency and disaster, this new technology can be used to meet the user’s needs. Cognitive radio is an intelligent wireless communication system that can perceive their environment, learn behavior and environmental patterns and appropriately adapt themselves to satisfy the immediate needs of the user, network, and radio environment. In other words, once cognitive radios can find the opportunities using the “spectrum holes” for communications, cognitive radio networking to transport packets on top of cognitive radio links is a must to successfully facilitate useful applications and services. A mobile terminal with cognitive radio capabilities can sense, detect and monitor the surrounding communication environments like spectrum holes, geographic location, and available wire/wireless communication systems/networks then reconfigure their own operating characteristics by adjusting the system parameters to best match those communication environments. II. NETWORK ARCHITECTURE A cognitive radio in Cognitive Radio Network (CRN) can sense available networks and communication systems around it. A Cognitive Radio Network (CRN) is thus not just another network to interconnect cognitive radios. The CRNs are composed of various kinds of communication systems and networks, and can be viewed as s sort of heterogeneous networks. The heterogeneity exists in wireless access technologies, networks, user terminals, applications, and service providers. The design of cognitive radio network architecture is toward the objective of improving the entire network utilization, rather than just link spectral efficiency. The network utilization means the users can always fulfill their demands anytime and anywhere through accessing CRNs. The CRNs can be deployed in Ad hoc, and mesh architectures. The basic components of CRNs are Mobile Station (MS), Base Station/Access Point (BSs/APs) and Backbone/Core Networks. A. Ad-hoc Architecture. Ad hoc networks are composed of Cognitive Radio devices that are self organizing and can be deployed without any infrastructure present. If a Mobile Station (MS) with Cognitive capabilities recognizes that there are some other MS or cognitive users nearby they can set up a link through certain communication protocols and thus form an ad hoc network. Each MS or Cognitive user forms a node of the ad hoc network. The links between nodes may be set up by different communication technology. Each Cognitive user decides its action based on a local observation and with cooperation schemes the observed information can be exchanged among other users to become aware on the network. Thus the cognitive users can communicate with other cognitive users through the