Cognitive radio

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Cognitive radio

• The idea of Cognitive radio was first presented
  in a article by Joseph Mitola III and Gerald Q.
  Maguire, Jr, in year 2000
• A novel approach for wireless communication that
  Mitola 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 wireless services
  most appropriate to those needs
• It was thought as a final point towards
  software-defined radio platform should evolve -
  fully reconfigurable wireless black-box that
  changes its communication functions depending on
  network and/or user demands

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Cognitive Radio

• If you look at the entire RF frequency up to 100
  GHz, and take a snapshot at any given time,
  you'll see that only five to ten percent of it is
  being used. So there's 90 GHz of available
  bandwidth."
• -- Ed Thomas, Former Chief Engr., FCC
• 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
• cellular network bands are overloaded in most
  parts of the world but amateur radio or paging
  frequencies not
• 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.

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cognitive radio

• According to Institute of Electrical and
  Electronic Engineers (IEEE), the cognitive radio
  is a radio transmitter/receiver that is designed
  to intelligently detect whether a particular
  segment of the radio spectrum is currently in use
  and to jump into (or out of) the
  temporarily-unused spectrum very rapidly without
  interfering with the transmissions of other
  users.

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• 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.

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Terminology

• Full Cognitive Radio ("Mitola radio") in which
  every possible parameter observed by wireless
  node and/or network is taken into account while
  making decision 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.
• 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 WPAN-WLAN coexistence Task Group 2
  (TG2)
• Unlicensed Band Cognitive Radio when cognitive
  radio can only utilize unlicensed parts of radio
  frequency sprectrum. An example of Unlicensed
  Band Cognitive Radio is IEEE_802.19 Coexistence
  Technical Advisory Group (TAG)

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Technology

• A software-defined radio (SDR) system is a radio
  communication system which uses software for the
  modulation and demodulation of radio signals.
• 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.

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Technology

• 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
• with increasing number of cooperating sensing
  nodes decreases probability of false detection

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Technology

• To adaptively fill free radio frequency bands
  OFDM seems to be a perfect candidate. In a
  Spectrum Pooling system free bands sensed by
  nodes are immediately filled by OFDM subbands
• Some of the applications of Spectrum Sensing
  Cognitive Radio including emergency networks and
  WLAN higher throughput and transmission distance
  extentions

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