Cooperative Beamforming and User Selection for Improving the Security of Relay-Aided Systems

Tiep M. Hoang, Trung Q. Duong, Himal A. Suraweera, Chintha Tellambura, H. Vincent Poor

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


A relay network in which a source wishes to convey a confidential message to a legitimate destination with the assistance of trusted relays is considered. In particular, cooperative beamforming and user selection techniques are applied to protect the confidential message. The secrecy rate (SR) and secrecy outage probability (SOP) of the network are investigated first, and a tight upper bound for the SR and an exact formula for the SOP are derived. Next, asymptotic approximations for the SR and SOP in the high signal-to-noise ratio (SNR) regime are derived for two different schemes: 1) cooperative beamforming and 2) multiuser selection. Furthermore, a new concept of cooperative diversity gain, namely, adapted cooperative diversity gain (ACDG), which can be used to evaluate the security level of a cooperative relaying network, is investigated. It is shown that the ACDG of cooperative beamforming is equal to the conventional cooperative diversity gain of traditional multiple-input single-output networks, while the ACDG of the multiuser scenario is equal to that of traditional single-input multiple-output networks.

Original languageEnglish (US)
Article number7303925
Pages (from-to)5039-5051
Number of pages13
JournalIEEE Transactions on Communications
Issue number12
StatePublished - Dec 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


  • Large scale relaying
  • Physical layer security
  • cooperative beamforming
  • cooperative diversity
  • decode-and-forward relays


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