Cognitive radio is a paradigm for wireless communication in which either a network or a wireless node changes its transmission or reception parameters to communicate efficiently avoiding interference with licensed or unlicensed users. This alteration of parameters is based on the active monitoring of several factors in the external and internal radio environment, such as radio frequency spectrum, user behaviour and network state. Look up Cognition in Wiktionary, the free dictionary. ... For the use of the term in networking, see Wireless networking. ... Communication is a process that allows organisms to exchange information by several methods. ... For the scientific and engineering discipline studying computer networks, see Computer networking. ... For the use of the term in networking, see Wireless networking. ... Network node (NN): A grouping of one or more network elements (at one or more sites) which provides network related functions, and is administered as a single entity. ... In telecommunications, transmission is the act of transmitting electrical messages (and the associated phenomena of radiant energy that passes through media). ... Look up reception in Wiktionary, the free dictionary. ... The factual accuracy of this article is disputed. ... It has been suggested that this article or section be merged with Radio waves. ... A telecommunications network is a network of telecommunications links arranged so that messages may be passed from one part of the network to another over multiple links. ...

History

The idea of cognitive radio was first presented officially in an article by Joseph Mitola III and Gerald Q. Maguire, Jr.^[1] It was a novel approach in wireless communications that Mitola later described as: Look up Cognition in Wiktionary, the free dictionary. ...

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 wireless services most appropriate to those needs.^[2] Look up Personal digital assistant in Wiktionary, the free dictionary. ...

It was thought of as an ideal goal towards which a software-defined radio platform should evolve: a fully reconfigurable wireless black-box that automatically changes its communication variables in response to network and user demands. A software-defined radio (SDR) system is a radio communication system which can tune to any frequency band and receive any modulation across a large frequency spectrum by means of programmable hardware which is controlled by software. ... Black box is technical jargon for a device or system or object when it is viewed primarily in terms of its input and output characteristics. ...

Regulatory bodies in various countries (including the Federal Communications Commission in the United States, and Ofcom in the United Kingdom) found that most of the Radio frequency spectrum was inefficiently utilized.^[3] For example, cellular network bands are overloaded in most parts of the world, but amateur radio and paging frequencies are not. Independent studies performed in some countries confirmed that observation,^[4][5] and concluded that spectrum utilization depends strongly on time and place. Moreover, fixed spectrum allocation prevents rarely used frequencies (those assigned to specific services) from being used by unlicensed users, even when their transmissions would not interfere at all with the assigned service. This was the reason for allowing unlicensed users to utilize licensed bands whenever it would not cause any interference (by avoiding them whenever legitimate user presence is sensed). This paradigm for wireless communication is known as Cognitive Radio. The FCCs official seal. ... Ofcom is a regulator for communication industries in the United Kingdom. ... It has been suggested that this article or section be merged with Radio waves. ... The tone or style of this article or section may not be appropriate for Wikipedia. ... Amateur radio station with modern solid-state transceiver featuring LCD display and DSP capabilities Amateur radio, often called ham radio, is a hobby that uses various types of radio broadcasting equipment to communicate with other radio amateurs for public service, recreation and self-training. ... It has been suggested that this article or section be merged with pager. ... Look up Cognition in Wiktionary, the free dictionary. ...

Terminology

Depending on the set of parameters taken into account in deciding on transmission and reception changes, and for historical reasons, we can distinguish certain types of cognitive radio. The main two are:

• Full Cognitive Radio ("Mitola radio"): in which every possible parameter observable by a wireless node or network is taken into account.
• Spectrum Sensing Cognitive Radio: in which only the radio frequency spectrum is considered.

Also, depending on the parts of the spectrum available for cognitive radio, we can distinguish: It has been suggested that this article or section be merged with Radio waves. ...

• Licensed Band Cognitive Radio: in which cognitive radio is capable of using bands assigned to licensed users, apart from unlicensed bands, such as U-NII band or ISM band. One such system is described in the IEEE 802.15 Task group 2 specification.^[6]
• Unlicensed Band Cognitive Radio: which can only utilize unlicensed parts of radio frequency spectrum. An example of Unlicensed Band Cognitive Radio is IEEE 802.19.^[7]

The Unlicensed National Information Infrastructure (U-NII) radio band is part of the radio frequency spectrum used by IEEE-802. ... The industrial, scientific and medical (ISM) radio bands were originally reserved internationally for non-commercial use of RF electromagnetic fields for industrial, scientific and medical purposes. ... IEEE 802. ... It has been suggested that this article or section be merged with Radio waves. ...

Technology

Although cognitive radio was initially thought of as a software-defined radio extension (Full Cognitive Radio), most of the research work is currently focusing on Spectrum Sensing Cognitive Radio, particularly in the TV bands. The essential problem of Spectrum Sensing Cognitive Radio is in designing high quality spectrum sensing devices and algorithms for exchanging spectrum sensing data between nodes. It has been shown^[8] that a simple energy detector cannot guarantee the accurate detection of signal presence, calling for more sophisticated spectrum sensing techniques and requiring information about spectrum sensing to be exchanged between nodes regularly. Increasing the number of cooperating sensing nodes decreases the probability of false detection.^[9] A software-defined radio (SDR) system is a radio communication system which can tune to any frequency band and receive any modulation across a large frequency spectrum by means of programmable hardware which is controlled by software. ... See TV (disambiguation) for other uses and Television (band) for the rock band European networks National In much of Europe television broadcasting has historically been state dominated, rather than commercially organised, although commercial stations have grown in number recently. ...

Filling free radio frequency bands adaptively (OFDM) seems to be the ideal approach. In fact, Timo A. Weiss and Friedrich K. Jondral of the University of Karlsruhe proposed a Spectrum Pooling system^[10] in which free bands sensed by nodes were immediately filled by OFDM subbands. It has been suggested that this article or section be merged with Radio waves. ... Orthogonal frequency division modulation (OFDM, also called orthogonal frequency division multiplexing) is a technique for the modulation of digital information onto an analog carrier electromagnetic (e. ... The Universität Karlsruhe (TH) (also called Fridericiana / University of Karlsruhe) recently merged with Forschungszentrum Karlsruhe to form the Karlsruhe Institute of Technology (KIT). ... Orthogonal frequency division modulation (OFDM, also called orthogonal frequency division multiplexing) is a technique for the modulation of digital information onto an analog carrier electromagnetic (e. ...

Applications of Spectrum Sensing Cognitive Radio include emergency networks and WLAN higher throughput and transmission distance extensions. Professional Mobile Radio (also known as Private Mobile Radio (PMR) in the UK and Land Mobile Radio (LMR) in North America) are field radio communications systems which use portable, mobile, base station, and dispatch console radios and are sometimes based on such standards as MPT-1327, TETRA and APCO 25... Wikipedia does not yet have an article with this exact name. ... In communication networks, throughput is the amount of digital data per time unit that is delivered over a physical or logical link, or that is passing through a certain network node. ... In telecommunications, transmission is the act of transmitting electrical messages (and the associated phenomena of radiant energy that passes through media). ...

Main functions

The main functions of Cognitive Radios are:^[11]

• Spectrum Sensing: detecting the unused spectrum and sharing it without harmful interference with other users, it is an important requirement of the Cognitive Radio network to sense spectrum holes, detecting primary users is the most efficient way to detect spectrum holes. Spectrum sensing techniques can be classified into three categories:
  • Transmitter detection: cognitive radios must have the capability to determine if a signal from a primary transmitter is locally present in a certain spectrum, there are several approaches proposed:
    • matched filter detection
    • energy detection
    • cyclostationary feature detection
  • Cooperative detection: refers to spectrum sensing methods where information from multiple Cognitive radio users are incorporated for primary user detection.
  • Interference based detection.

• Spectrum Management: Capturing the best available spectrum to meet user communication requirements. Cognitive radios should decide on the best spectrum band to meet the Quality of service requirements over all available spectrum bands, therefore spectrum management functions are required for Cognitive radios, these management functions can be classified as:
  • spectrum analysis
  • spectrum decision

• Spectrum Mobility: is defined as the process when a cognitive radio user exchanges its frequency of operation. Cognitive radio networks target to use the spectrum in a dynamic manner by allowing the radio terminals to operate in the best available frequency band, maintaining seamless communication requirements during the transition to better spectrum

• Spectrum Sharing: providing the fair spectrum scheduling method, one of the major challenges in open spectrum usage is the spectrum sharing. It can be regarded to be similar to generic media access control MAC problems in existing systems

A matched filter is obtained by correlating a known signal, or template, with an unknown signal to detect the presence of the template in the unknown signal. ... Cyclostationary is a synonym for spectral conjugate self-coherence. ... In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service (QoS) refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the... The Media Access Control (MAC) data communication protocol sub-layer, also known as the Medium Access Control, is a part of the data link layer specified in the seven-layer OSI model (layer 2). ...

Cognitive radio (CR) vs. Intelligent antenna (IA)

Intelligent antenna (or smart antenna) is antenna technology that does spatial beamforming and spatial coding to cancel interference; however, it requires high cost multiple or cooperative antenna array. On the contrary, cognitive radio (CR) allows user terminals to sense a spectrum particles whether to be used or not, so as to share the spectrum among neighbor users, which is so, low-cost spectrum sharing technology. The following table compares the different points between two advanced approaches for the future wireless systems: Cognitive radio (CR) vs. Intelligent antenna (IA). Understanding of SISO, SIMO, MISO and MIMO Multiple-input and multiple-output (antennas), or MIMO, (pronounced mee-moh or mai-moh) refers to the use of multiple antennas both at the transmitter and receiver to improve the performance of radio communication systems. ... Smart Antenna refers to a system of antenna arrays with smart signal processing algorithms that are used to identify the direction of arrival (DOA) of the signal, and use it to calculate beamforming vectors, to track and locate the antenna beam on the mobile/target. ...

// Ultra-wide-band (also UWB, and ultra-wideband, ultra-wide band, etc. ...

See also

• Software-defined radio
• OFDM
• Frequency assignment
• Ultra Wideband
• Intelligent antenna (IA) is antenna technology which exploits electronic intelligence to enhance the performance of radio communication systems, as well as being used to enhance the performance of freeband systems. For instance, IA-based multiple antenna terminals enable to communicate multiple radio links simultaneously up to the number of embedded multiple antennas.
• Dirty paper coding (DPC) pre-cancels the known interference signal at the transmitter without the additional transmit power regardless of knowing the interference at the receiver, which can be used to optimize cognitive wireless network channels.^[12]
• Cooperative wireless communications

A software-defined radio (SDR) system is a radio communication system which can tune to any frequency band and receive any modulation across a large frequency spectrum by means of programmable hardware which is controlled by software. ... Orthogonal frequency division modulation (OFDM, also called orthogonal frequency division multiplexing) is a technique for the modulation of digital information onto an analog carrier electromagnetic (e. ... // Ultra-wide-band (also UWB, and ultra-wideband, ultra-wide band, etc. ... Understanding of SISO, SIMO, MISO and MIMO Multiple-input and multiple-output (antennas), or MIMO, (pronounced mee-moh or mai-moh) refers to the use of multiple antennas both at the transmitter and receiver to improve the performance of radio communication systems. ... Dirty paper coding (DPC) is a coding technique that pre-cancels a known interference where the known interference is a interference known at the transmitter before self-data transmission. ... The wireless ad-hoc network increases the flexibility of wireless networking at the cost of increased multi-user interference. ...

References

1. ^ http://ieeexplore.ieee.org/iel5/98/17080/00788210.pdf?tp=&arnumber=788210&isnumber=17080
2. ^ http://www.it.kth.se/~jmitola/Mitola_Dissertation8_Integrated.pdf
3. ^ http://www.spectrum.ieee.org/WEBONLY/publicfeature/mar04/0304scar.html
4. ^ http://ieeexplore.ieee.org/iel5/9626/30419/01399240.pdf?tp=&arnumber=1399240&isnumber=30419
5. ^ http://ieeexplore.ieee.org/iel5/35/28504/01273768.pdf?tp=&arnumber=1273768&isnumber=28504
6. ^ http://ieee802.org/15/pub/TG2.html
7. ^ http://grouper.ieee.org/groups/802/19
8. ^ http://www.eecs.berkeley.edu/wireless/posters/WFW05_cognitive.pdf
9. ^ http://ieeexplore.ieee.org/iel5/4234/30631/01413630.pdf?tp=&arnumber=1413630&isnumber=30631
10. ^ http://ieeexplore.ieee.org/iel5/35/28504/01273768.pdf?tp=&arnumber=1273768&isnumber=28504
11. ^ http://www.ece.gatech.edu/research/labs/bwn/radio.pdf
12. ^ Natasha Devroye, Patrick Mitran and V. Tarokh, Limits on Communication in a Cognitive Radio Channel," IEEE Communications Magazine, pp. 44-49, June 2006.

External links

• Adaptive Ad-hoc Freeband Communications - Dutch research project aiming to realize ambient, intelligent radio communications.
• 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
• WWRF WG6 - Cognitive Wireless Networks and Systems