On the performance of cooperative-diversity networks with the Nth best-relay selection scheme

  • Authors:
  • Salama S. Ikki;Mohamed H. Ahmed

  • Affiliations:
  • Electrical and Computer Engineering Department, University of Waterloo, Waterloo, ON, Canada;Electrical and Computer Engineering Department, Memorial University, St. John's, NL, Canada

  • Venue:
  • IEEE Transactions on Communications
  • Year:
  • 2010

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Abstract

In this letter, we consider the adaptive decodeand-forward (DF) and amplify-and-forward (AF) cooperative-diversity systems with the Nth best-relay selection scheme. In the best-relay selection scheme, from the set of M relays the best relay only forwards the source signal to the destination. However, the best relay might be unavailable; hence we might resort to the second, third or generally the Nth best relay. We derive closed-form expressions for the symbol error probability, outage probability and asymptotic error probability. In particular, we derive a closed-form expression for the probability density function (PDF) of the signal-to-noise ratio (SNR) of the relayed signal at the destination node. Then, we find a closed-form expression for the moment generating function (MGF) of the output SNR at the destination. This MGF is used to derive the closed-form expressions of the performance metrics. All these expressions are derived over identical and non-identical Rayleigh fading channels. Results show that with the Nth best relay the diversity order is equal to (M-N+2) where M is the number of relays.