Cognitive radio Cognitive radio is a paradigm for wireless communication in which either network or wireless node itself changes particular transmission or reception parameters to execute its tasks efficiently without interfering with the licensed users . This parameter alteration is based on observations of several factors from external and internal cognitive radio environment , such as radio frequency spectrum , user behaviour , and network state . History The idea of Cognitive radio was first presented officially in the article by Joseph Mitola III and Gerald Q. Maguire , Jr . . It was a novel approach for wireless communication that Mitola III later described as `` the point in which wireless personal digital assistants ( PDAs ) and the related networks are sufficiently computationally intelligent about radio resources and related computer-to-computer communications to detect user communications needs as a function of use context , and to provide radio resources and wire less services most appropriate to those needs '' . It was thought of as a final point towards which a software-defined radio platform should evolve - fully reconfigurable wireless black-box that changes its communcation functions depending on network and/or user demands . On the other hand regulatory bodies in various countries ( such as Federal Communications Commission in the United States ) found that most of the Radio frequency spectrum was inefficiently utilized . For example cellular network bands are overloaded in most parts of the world but amateur radio or paging frequencies are not ( independent studies performed in some countries confirmed that observation , and concluded that spectrum utilization depends strongly on time and place ) . Moreover fixed spectrum allocation caused that rarely used frequencies , assigned to specific services , cannot be accessed by non-licensed users , even if non-licensed user transmission does not introduce any interference to the pre-empted service . This was the reason for allowing non-legitimate users to utilize licensed bands , assuming it would not cause any interference ( thus deferring from licensed bands whenever legitimate user presence was sensed ) . Such a paradigm for wireless communication is also called Cognitive Radio . Terminology Depending on historical reasons and set of parameters taken into account while making decisions on transmission or/and reception alteration we can distinguish many types of cognitive radios . The main two are : Full Cognitive Radio ( `` Mitola radio `` ) : in which every possible parameter observed by a wireless node and/or network is taken into account while making decisions on transmission and/or reception parameter change . Spectrum Sensing Cognitive Radio : this is a special case of Full Cognitive Radio in which only radio frequency spectrum is observed . Also depending on the parts of the spectrum available for cognitive radio we can distinguish : Licensed Band Cognitive Radio : when cognitive radio is capable of using bands assigned to licensed users , apart from utilization unlicensed bands such as UNII band or ISM band . One of the Licensed Band Cognitive Radio-like systems is IEEE 802.15 Task group 2 specification . Unlicensed Band Cognitive Radio : when cognitive radio can only utilize unlicensed parts of radio frequency spectrum . An example of Unlicensed Band Cognitive Radio is IEEE 802.19 . Technology Although cognitive radio was initially thought of as a software-defined radio extension ( Full Cognitive Radio ) most of the research work currently is focusing on Spectrum Sensing Cognitive Radio - particularly on the utilization of TV bands for communication . The essential problem of Spectrum Sensing Cognitive Radio is design of high quality spectrum sensing devices and algorithms for exchanging spectrum sensing data between nodes . It has been shown in that a simple energy detector cannot guarantee accurate detection of signal presence . This calls for more sophisticated spectrum sensing techniques and requires that information about spectrum sensing must be exchanged between nodes regularly ( in authors show that with increasing number of cooperating sensing nodes decreases probability of false detection ) . To adaptively fill free radio frequency bands OFDM seems to be a perfect candidate . Indeed in Timo A. Weiss and Friedrich K. Jondral from University of Karlsruhe proposed a Spectrum Pooling system in which free bands sensed by nodes were immediately filled by OFDM subbands . Some of the applications of Spectrum Sensing Cognitive Radio including emergency networks and WLAN higher throughput and transmission distance extensions . See also Software-defined radio OFDM Frequency assignment Ultra Wideband External links Cognitive Radio Technology - Edited by Bruce Fette - Published August 2006 Many more resources on Cognitive Radio and SDR - from University of South Florida ( USF ) - WCSP Group Adaptive Ad-hoc Freeband Communications - Dutch research project A Good Overview of Cognitive Radio Berkeley Wireless Research Center Cognitive Radio Workshop - first workshop on cognitive radio ; its focus was mainly on research issues in topic Joseph Mitola III , Cognitive Radio : An Integrated Agent Architecture for Software Defined Radio , Royal Institute of Technology ( KTH ) Stockholm , Sweden , 8 May , 2000 , ISSN 1403 - 5286. - PhD dissertation in which cognitive radio architecture was firstly defined in detail Cognitive Radio Technologies Proceeding of Federal Communications Commission - Federal Communications Commission rules on cognitive radio Scientific American Magazine ( March 2006 Issue ) Cognitive Radio Categories : Radio technology | Wireless networking In other languages : Español 