Complex-field coding for OFDM over fading wireless channels

Zhengdao Wang, Georgios B. Giannakis

Research output: Contribution to journalArticlepeer-review

157 Scopus citations

Abstract

Orthogonal frequency-division multiplexing (OFDM) converts a time-dispersive channel into parallel sub-channels, and thus facilitates equalization and (de)coding. But when the channel has nulls close to or on the fast Fourier transform (FFT) grid, uncoded OFDM faces serious symbol recovery problems. As an alternative to various error-control coding techniques that have been proposed to ameliorate the problem, we perform complex-field coding (CFC) before the symbols are multiplexed. We quantify the maximum achievable diversity order for independent and identically distributed (i.i.d.) or correlated Rayleigh-fading channels, and also provide design rules for achieving the maximum diversity order. The maximum coding gain is given, and the encoder enabling the maximum coding gain is also found. Simulated performance comparisons of CFC-OFDM with existing block and convolutionally coded OFDM alternatives favor CFC-OFDM for the code rates used in a HiperLAN2 experiment.

Original languageEnglish (US)
Pages (from-to)707-720
Number of pages14
JournalIEEE Transactions on Information Theory
Volume49
Issue number3
DOIs
StatePublished - Mar 2003

Bibliographical note

Funding Information:
Manuscript received April 20, 2001; revised November 1, 2002. This work was supported by the NSF under Grant CCR-9805350 and by the NSF under the Wireless Initiative Grant 9979443. The material in this paper was presented in part at the the Workshop on Signal Processing Advances in Wireless Communication, Taoyuan, Taiwan, ROC, March 2001. Z. Wang is with the Department of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011 USA (e-mail: zhengdao@iastate.edu). G. B. Giannakis is with the Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 USA (e-mail: georgios@ece.umn.edu). Communicated by T. Fuja, Associate Editor At Large. Digital Object Identifier 10.1109/TIT.2002.808101

Keywords

  • Analog codes
  • Coding gain
  • Complex-field coding (CFC)
  • Diversity order
  • Fading
  • Maximum-distance separable (MDS)
  • Orthogonal frequency-division multiplexing (OFDM)
  • Real-number codes

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