Long codes for generalized FH-OFDMA through unknown multipath channels

Shengli Zhou, Georgios B. Giannakis, Anna Scaglione

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


A generalized frequency-hopping (GFH) orthogonal frequency-division multiple-access (OFDMA) system is developed in this paper as a structured long code direct-sequence code-division multiple-access (DS-CDMA) system in order to bridge frequency-hopped multicarrier transmissions with long code DS-CDMA. Through judicious code design, multiuser interference is eliminated deterministically in the presence of unknown frequency-selective multipath channels. Thanks to frequency-hopping, no single user suffers from consistent fading effects and constellation-irrespective channel indentifiability is guaranteed regardless of channel nulls. A host of blind channel estimation algorithms are developed trading off complexity with performance. Two important variants, corresponding to slow- and fast-hopping, are also addressed with the latter offering symbol recovery guarantees. Performance analysis and simulation results illustrate the merits of GFH-OFDMA relative to conventional OFDMA and long code DS-CDMA with pseudorandom noise codes and RAKE reception.

Original languageEnglish (US)
Pages (from-to)721-733
Number of pages13
JournalIEEE Transactions on Communications
Issue number4
StatePublished - Apr 2001
Externally publishedYes


  • Blind channel estimation
  • Frequency-hopping
  • Multicarrier CDMA
  • Multipath fading channels
  • Spread spectrum systems

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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