Capacity of cognitive interference channels with and without secrecy

Yingbin Liang, Anelia Somekh-Baruch, H. Vincent Poor, Shlomo Shamai, Sergio Verdu

Research output: Contribution to journalArticlepeer-review

139 Scopus citations


Like the conventional two-user interference channel, the cognitive interference channel consists of two transmitters whose signals interfere at two receivers. It is assumed that there is a common message (message 1) known to both transmitters, and an additional independent message (message 2) known only to the cognitive transmitter (transmitter 2). The cognitive receiver (receiver 2) needs to decode messages 1 and 2, while the noncognitive receiver (receiver 1) should decode only message 1. Furthermore, message 2 is assumed to be a confidential message which needs to be kept as secret as possible from receiver 1, which is viewed as an eavesdropper with regard to message 2. The level of secrecy is measured by the equivocation rate. In this paper, a single-letter expression for the capacity-equivocation region of the discrete memoryless cognitive interference channel is obtained. The capacity-equivocation region for the Gaussian cognitive interference channel is also obtained explicitly. Moreover, particularizing the capacity-equivocation region to the case without a secrecy constraint, the capacity region for the two-user cognitive interference channel is obtained, by providing a converse theorem.

Original languageEnglish (US)
Pages (from-to)604-619
Number of pages16
JournalIEEE Transactions on Information Theory
Issue number2
StatePublished - 2009

All Science Journal Classification (ASJC) codes

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


  • Capacity-equivocation region
  • Cognitive communication
  • Confidential messages
  • Interference channel
  • Rate splitting
  • Secrecy capacity region


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