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Symbol spreading for ultrawideband systems based on multiband OFDM

  • I Ramachandran
  • Y P Nakache
  • P Orlik
  • J Zhang
  • Andreas Molisch
Publiceringsår: 2004
Språk: Engelska
Sidor: 1204-1209
Publikation/Tidskrift/Serie: 15th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2004.
Volym: 2
Dokumenttyp: Konferensbidrag


We investigate the effect of symbol spreading on the performance of ultrawideband systems based on multiband OFDM. Ultrawideband channels offer the possibility of very high frequency diversity, as the used bandwidth is much larger than the coherence bandwidth of the channel. In multiband-OFDM, frequency diversity stems from (i) forward error correction coding, which distributes the symbols associated with one bit among different tones, and (ii) interleaving, which distributes the symbols among different employed frequency bands. We show that for weak (rate 3/4) error correcting codes, the achieved diversity order is insufficient. However, the use of Walsh-Hadamard spreading gives additional diversity within each frequency band and greatly improves the performance. Furthermore, we propose a novel scheme for grouping OFDM tones before the spreading is performed. This grouping gives additional flexibility in the system design.


  • Electrical Engineering, Electronic Engineering, Information Engineering
  • diversity reception
  • error correction codes
  • forward error correction
  • telecommunication channels
  • ultra wideband communication
  • OFDM modulation


IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2004
  • ISBN: 0-7803-8523-3

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