Cognitive radio: An information-theoretic perspective

Aleksandar Jovičić, Pramod Viswanath

Research output: Contribution to journalArticlepeer-review


In this paper, we consider a communication scenario in which the primary and the cognitive radios wish to communicate to different receivers, subject to mutual interference. In the model that we use, the cognitive radio has noncausal knowledge of the primary radio's codeword. We characterize the largest rate at which the cognitive radio can reliably communicate under the constraint that 1) no rate degradation is created for the primary user, and 2) the primary receiver uses a single-user decoder just as it would in the absence of the cognitive radio. The result holds in a "low-interference" regime in which the cognitive radio is closer to its receiver than to the primary receiver. In this regime, our results are subsumed by the results derived in a concurrent and independent work (Wu et al, 2007). We also demonstrate that, in a "high-interference" regime, multiuser decoding at the primary receiver is optimal from the standpoint of maximal jointly achievable rates for the primary and cognitive users.

Original languageEnglish (US)
Pages (from-to)3945-3958
Number of pages14
JournalIEEE Transactions on Information Theory
Issue number9
StatePublished - 2009


  • Cognitive radio
  • Costa precoding
  • Dirty-paper coding
  • Interference channel
  • Spectral reuse
  • Wireless networks

ASJC Scopus subject areas

  • Information Systems
  • Computer Science Applications
  • Library and Information Sciences


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