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  • Research Article
  • Open Access

Cooperative Communications over Flat Fading Channels with Carrier Offsets: A Double-Differential Modulation Approach

EURASIP Journal on Advances in Signal Processing20082008:531786

  • Received: 27 October 2007
  • Accepted: 1 April 2008
  • Published:


We propose double-differential (DD) modulation for the amplify-and-forward protocol over Nakagami- fading channels with carrier offsets. We propose an emulated maximum ratio combining (EMRC) decoder, which could be used by the double-differential receiver in the absence of exact channel knowledge. Approximate bit error rate (BER) analysis is performed for the proposed double-differential modulation-based cooperative communication system. The proposed double-differential system is immune to random carrier offsets, whereas the conventional single-differential modulation-based cooperative system breaks down. In addition, the proposed scheme is able to perform better than the same rate training-based cooperative system which utilizes training data for finding estimates of carrier offsets and channel gains.


  • Error Rate
  • Information Technology
  • Training Data
  • Communication System
  • Quantum Information

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Authors’ Affiliations

UniK - University Graduate Center, University of Oslo, P.O. Box 70, 25 Instituttveien, 2027 Kjeller, Norway


© Manav R. Bhatnagar et al. 2008

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.