Enhanced primary and secondary performance through cognitive relaying and leveraging primary feedback

Doha R. Hamza, Sonia Aïssa

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


We consider a spectrum-sharing system, where the primary terminal operates in a time-slotted fashion and is active only when it has a packet to send. The secondary terminal uses spectrum sensing results and the primary automatic repeat request (ARQ) feedback to access the channel probabilistically. To enhance the primary's system performance, the secondary user (SU) acts as a relay for the primary user (PU) in the event of transmission failure on the direct link of the latter. Closed-form expressions for the primary and secondary throughputs are obtained for the described scheme. The optimal medium access probabilities are then obtained by maximizing the secondary throughput subject to constraints that guarantee the stability of the considered queues, a minimum primary throughput, and a maximum primary queueing delay. The results clearly indicate the benefits of cognitive relaying in enhancing the throughput performance for both the PU and SU. Furthermore, by guaranteeing minimum rate and maximum delay requirements, our scheme is shown to provide a definitive notion of protection for the licensed users of the network. © 2013 IEEE.
Original languageEnglish (US)
Pages (from-to)2236-2247
Number of pages12
JournalIEEE Transactions on Vehicular Technology
Issue number5
StatePublished - Jun 2014

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01

ASJC Scopus subject areas

  • Automotive Engineering
  • Applied Mathematics
  • Computer Networks and Communications
  • Electrical and Electronic Engineering
  • Aerospace Engineering


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