NeXt generation/dynamic spectrum access/cognitive radio wireless networks: A survey

Ian F. Akyildiz, Won Yeol Lee, Mehmet C. Vuran, Shantidev Mohanty

Research output: Contribution to journalArticlepeer-review

5236 Scopus citations


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% with a 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 NeXt Generation (xG) Networks as well as Dynamic Spectrum Access (DSA) and cognitive radio networks. The term xG networks is used throughout the paper. The novel functionalities and current research challenges of the xG networks are explained in detail. More specifically, a brief overview of the cognitive radio technology is provided and the xG network architecture is introduced. Moreover, the xG 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. Finally, the cross-layer design challenges in xG networks are discussed.

Original languageEnglish (US)
Pages (from-to)2127-2159
Number of pages33
JournalComputer Networks
Issue number13
StatePublished - Sep 15 2006
Externally publishedYes


  • Cognitive radio networks
  • Dynamic spectrum access networks
  • Next generation networks
  • Spectrum management
  • Spectrum mobility
  • Spectrum sensing
  • Spectrum sharing

ASJC Scopus subject areas

  • Computer Networks and Communications


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