Cognitive Communications

Background

CR is the technology allowing radio equipment to obtain knowledge of its radio environment and to dynamically adjust its operational parameters in order to improve its performance (Mitola & Maguire, 1999; Drozd et al., Mitola, 2000). SDR technologies are a natural platform on which to build in new cognitive features: SDR functionality is seen as the foundation for development of CR functionality. In particular, SDR is a radio communication system where components that in the past have been typically implemented in hardware (e.g. mixers, filters, modulators/demodulators, detectors, etc.) are instead implemented by means of software.

Cognitive radio as a new concept was firstly introduced by Joseph Mitola and Gerald Maguire in (Mitola & Maguire, 1999) where CR is presented as an extension of SDR enhancing flexibility of personal wireless services. Cognitive radio architecture as an integrated agent for SDR in the intersection of personal wireless technology and computational intelligence is further developed in Mitola's Doctoral Dissertation (Mitola, 2000). A CR is assumed to be a fully re-configurable radio device that can cognitively adapt itself (Haykin, 2005):

• 1.

  To the communications requirements of its user,

• 2.

  To the radio frequency environment in which it is operating,

• 3.

  To the various network and regulatory policies.

CR is an intelligent wireless communication system that is aware of its surrounding environment and uses the methodology of understanding by building to learn from the environment and adapt its internal states to statistical variations in the incoming radio frequency stimuli by making corresponding changes in certain operating parameters in real time, with two primary objectives: highly reliable communications whenever and wherever needed and efficient utilization of radio spectrum (Matinmikko et al., 2008). Fully capable CR is unlikely to be achieved in the next years, but certain CR features will be gradually implemented in radio equipment in the next future.