Effect of feedback delay on amplify-and-forward relay networks with beamforming

Himal A. Suraweera, Theodoros A. Tsiftsis, George K. Karagiannidis, Arumugam Nallanathan

Research output: Contribution to journalArticlepeer-review

60 Citations (Scopus)


In this paper, the decremental effect of beamforming with feedback delay on the performance of a two-hop amplify-and-forward (AF) relay network over Rayleigh-fading channels is investigated. An antenna configuration in which the source and the destination are equipped with multiple antennas, whereas the relay is equipped with a single antenna, is assumed. We derive new expressions for the outage probability and the average bit error rate (BER), which are useful for a large number of modulation schemes. To gain further insights, simple outage probability and average BER approximations at high signal-to-noise ratio (SNR) are also presented. It is shown that, whenever a feedback delay exists, the network is not capable of offering diversity gains. Furthermore, source and relay power allocation results show significantly different behavior with feedback delay. Numerical results supported by simulations are provided to show that feedback delay can severely degrade the performance of the considered AF relay system.

Original languageEnglish
Article number5710995
Pages (from-to)1265-1271
Number of pages7
JournalIEEE Transactions on Vehicular Technology
Issue number3
Publication statusPublished - Mar 2011
Externally publishedYes


  • Amplify-and-forward (AF)
  • average bit error rate (BER)
  • beamforming
  • feedback delay
  • relays

ASJC Scopus subject areas

  • Automotive Engineering
  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Applied Mathematics

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