Effects of CSI Knowledge on Secrecy of Threshold-Selection Decode-and-Forward Relaying

Chinmoy Kundu, Sarbani Ghose, Telex M.N. Ngatched, Octavia A. Dobre, Trung Q. Duong*, Ranjan Bose

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
245 Downloads (Pure)


This paper considers secrecy of a three node cooperative wireless system in the presence of a passive eavesdropper. The threshold-selection decode-and-forward relay is considered, which can decode the source message correctly only if a predefined signal-to-noise ratio (SNR) is achieved. The effects of channel state information (CSI) availability on secrecy outage probability (SOP) and ergodic secrecy rate (ESR) are investigated, and closed-form expressions are derived. Diversity is achieved from the direct and relaying paths both at the destination and at the eavesdropper by combinations of maximal-ratio combining and selection combining schemes. An asymptotic analysis is provided when each hop SNR is the same in the balanced case and when it is different in the unbalanced case. The analysis shows that both hops can be a bottleneck for secure communication; however, they do not affect the secrecy identically. While it is observed that CSI knowledge can improve secrecy, the amount of improvement for SOP is more when the required rate is low and for ESR when the operating SNR is also low. It is also shown that the source to eavesdropper link SNR is more crucial for secure communication.

Original languageEnglish
Article number8031880
Pages (from-to)19393-19408
JournalIEEE Access
Early online date12 Oct 2017
Publication statusEarly online date - 12 Oct 2017


  • Channel state information
  • cooperative diversity
  • decode-and-forward relay
  • ergodic secrecy rate
  • secrecy outage probability
  • threshold-selection relay

ASJC Scopus subject areas

  • Computer Science(all)
  • Materials Science(all)
  • Engineering(all)

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