An amplify-and-forward scheme for spectrum sharing in cognitive radio channels

Francesco Verde, Anna Scaglione, Donatella Darsena, Giacinto Gelli

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


In this paper, we propose a cognitive radio scheme that allows a secondary user (SU) to transmit over the same time-frequency slot of a primary user (PU), even when the PU is active. In our scheme, the SU amplifies and forwards the signal of the PU, by using as scaling factor the value of its information symbol to be transmitted towards the secondary receiver. The information-theoretic limits of the proposed protocol are investigated in terms of ergodic channel capacities of both the PU and SU links. It is shown that: 1) under certain operating conditions, the SU can superimpose its information symbols on the PU signal, without violating the cognitive radio principle of protecting the PU transmission; and 2) when the primary link is busy, the SU offers the PU its own transmitting power in exchange for a low-capacity communication channel, which improves the packet delay performance of the SU. In this barter, the tempting incentive for the PU consists of a noticeable improvement of its achievable rate at the price of a slight increase in the computational complexity of the primary receiver.

Original languageEnglish (US)
Pages (from-to)5629-5642
Number of pages14
JournalIEEE Transactions on Wireless Communications
Issue number10
StatePublished - Oct 1 2015


  • Amplify-and-forward relaying
  • Cognitive radio
  • Ergodic channel capacity
  • Wireless communications

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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