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  • Research Article
  • Open Access

Opportunistic Cognitive Relaying: A Win-Win Spectrum Sharing Scheme

EURASIP Journal on Wireless Communications and Networking20102010:263405

  • Received: 11 September 2009
  • Accepted: 15 April 2010
  • Published:


A cost-effective spectrum sharing architecture is proposed to enable the legacy noncognitive secondary system to coexist with the primary system. Specifically, we suggest to install a few intermediate nodes, namely, the cognitive relays, to conduct the spectrum sensing and coordinate the spectrum access. To achieve the goal of win-win between primary and secondary systems, the cognitive relay may act as a cooperator for both of them, and an Opportunistic Cognitive Relaying (OCR) scheme is specially devised. In this scheme, the cognitive relay opportunistically switches among three different working modes, that is, Relay for Primary Link (RPL), Relay for Secondary Link (RSL), or Relay for Neither of the Links (RNL), respectively, based on the channel-dependent observation of both systems. In addition, the transmit power for cognitive relay and secondary transmitter in each mode are optimally determined by maximizing the transmission rate of secondary system while keeping or even reducing the outage probability of primary system. Simulation results validate the efficiency of the proposed spectrum sharing scheme.


  • Information System
  • Transmission Rate
  • System Application
  • Outage Probability
  • Intermediate Node

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Authors’ Affiliations

Institute of Information and Communication Engineering, Zhejiang University, Hangzhou, Zhejiang, 310027, China


© Haiyan Luo et al. 2010

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.