Today’s wireless networks are characterized by a fixed spectrum assignment policy. However,a large portion of the assigned spectrum is used sporadically and geographical variations in the utilization of assigned spectrum ranges from 15% to 85% witha high variance in time.
The limited available spectrum and the inefficiency in the spectrum usage necessitate a new communication paradigm to exploit the existing wireless spectrum opportunistically. This new networking paradigm is referred to as cognitive radio networks. In this tutorial, the novel functionalities and current research challenges of the cognitive radio networks are explained indetail. More specifically, an overview of the cognitive radio technology is provided and the network architecture is introduced. Moreover, the cognitive network functions such as spectrum management, spectrum mobility and spectrum sharing are explained in detail. The influence of these functions on the performance of the upper layer protocols such as routing and transport are investigated and open research issues in these areas are also outlined.
The sort of mental processes described as cognitive are largely influenced by research which has successfully used this paradigm in the past. Consequently, this description tends to apply to processes such as memory, attention, perception, action, problem solving and mental imagery. Traditionally, emotion was not thought ofas a cognitive process. This division is now regarded as largely artificial and much research is currently being undertaken to examine the cognitive psychology of emotion; research also includes one's awareness of strategies and methods of cognition, known as metacognition.
Empirical research into cognition is usually scientific and quantitative, or involves creating models to describe or explain certain behaviors.While few people would deny that cognitive processes are a function of the brain, a cognitive theory will not necessarily make any reference to the brain or any other biological process (compare neurocognitive). It may purely describe behaviour in terms of information flow or function. Relatively recent fields of study such as cognitive science and neuro psychologyaim to bridge this gap, using cognitive paradigms to understand how the brain implements these information - processing functions (see also cognitive neuroscience), or how pure information - processing systems (e.g., computers) can simulate cognition (see also artificial intelligence). The branch of psychology that studies brain injury to infer normal cognitive function is called cognitive neuropsychology. The links of cognition to evolutionary demands are studied through the investigation of animal cognition. And conversely, evolutionary - based perspectives can inform hypotheses about cognitive functional systems evolutionary psychology.
"The theoretical school of thought derived from the cognitive approach is often called Cognitivism."
The term “COGNITIVE RADIO” has been derived from the word cognition. Now first weneed to look what this word actually mean.
Theterm cognition ( Latin: cognoscere, "to know" ) is used in several loosely to the related ways to refer to a faculty for the human - like processing of information, applying knowledge and changing preferences. Cognition or cognitive processes can be natural and artificial, conscious and not conscious; therefore, they are analyzed from different perspectives and in different contexts, in anesthesia, neurology, psychology, philosophy, systemic and computer science. The concept of cognition is closely related to such abstract concepts as mind, reasoning, perception, intelligence, learning, and many others that describe numerous capabilities of the human mind and expected properties of artificial or synthetic intelligence. Cognition is an abstract property of advanced living organisms; therefore, it is studied as a direct property of a brain or of an abstract mind on sub - symbolic and symbolic levels.
In psychology and in artificial intelligence, it is used to refer to the mental functions, mental processes and states of intelligent entities (humans, human organizations, highly autonomous robots), with a particular focus toward the study of such mental processes as comprehension, inferencing, decision - making, planning and learning (see also cognitive science and cognitivism). Recently, advanced cognitive researchers have been especially focused on the capacities of abstraction, generalization, concretization/specialization and meta - reasoning which descriptions involve such concepts as beliefs, knowledge, desires, preferences and intentions of intelligent individuals/objects/agents/systems.
Theterm "cognition" is also used in a wider sense to mean the act of knowing or knowledge, and may be interpreted in a social or cultural sense to describe the emergent development of knowledge and concepts within a group that culminates in both thought and action.
Consider a radio which autonomously detects and exploits empty spectrum to increase your file transfer rate. Suppose this same radio could remember the locations where your calls tend to drop and arrange for your call to be serviced by a different carrier for those locations. These are some of the ideas motivating the development of cognitive radio. In effect, a cognitive radio is a software radio whose control processes leverage situational knowledge and intelligent processing to work towards achieving some goal related to the needs of theuser, application, and/or network.
Arising from a logical evolution of the control processes of a software radio, cognitive radio presents the possibility of numerous revolutionary applications, foremost of which is opportunistic spectrum utilization. Cognitive Radio Technologies (CRT) was founded in 2007 by Dr. James Neel and Dr. Jeffrey Reed to speed the transition of cognitive radio from the laboratory to living room.With its extensive experience in the field of cognitive radio, CRT can help your products. Automatically detect and exploit unused spectrum Automatically detect and interoperate with varying network standards Improve performance. The rapid growth of wireless services over the past few years has created a huge and growing demand for radio spectrum. But with unused spectrum in short supply, researchers are now turning their attention to communications systems that can share frequencies without causing interference to each other. One promising approach is cognitive radio.
Cognitive radio utilizes a network, or wireless node, that can change transmission or reception parameters to avoid interference from licensed or unlicensed users inthe same frequency. The concept was developed by Defense Advance Research Products Agency (DARPA) scientist Joseph Mitola as a logical next step for the software defined radios (SDRs) that are emerging today in military and some commercial applications. SDRs use software to replicate filters, mixers, amplifiers and other traditionally hardware - based components to create a radio that can quickly shift between different operating modes, frequencies, protocols and other parameters.
Experts believe that cognitive radio technology may ultimately assist in improving transmission performance over different radio frequencies, particularly for security and military users. Although still an emerging technology, cognitive radio is seen as having great promise in a variety of fields, including public safety and mobile phone communications.
Two wireless networking researchers at the Rochester Institute of Technology have co-authored one of the first textbooks devoted to the study of cognitive radio networks. Cognitive Radio Networks by Fei Hu, an assistant professor of computer engineering at Rochester Institute of Technology, and Yang Xiao, an assistant professor of computer science at the University of Alabama, provides information and applications related to cognitive radio technology for use in research and classroom settings. The book is published by Boca Raton, Fla.-based CRC Press.
Huand Xiao hope their book will expand the development of cognitive radio applications. "The explosion of wireless communication over the last two decades has led to the need for spectrum - agile communications that are more efficient and less prone to interference from other radio transmissions,"Hu says. "This type of technology is particularly important for military and security transmissions where clear, uninterrupted communication is essential."
Cognitive Radio Networks covers a range of topics applicable for future cognitive radios aimed at business, consumer and government users, including research, management and support. The text also examines information theory and multiple access schemes for cognitive radio, as well as spectrum sensing mechanisms and protocol support.
Cognitive radio is still a ascent technology and researchers and students in the field require data and instruction related to best practices and technology applications,"
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