Iterative frequency domain channel estimation for DFT-precoded OFDM systems using in-band pilots

Chan Tong Lam, David D. Falconer, Florence Danilo-Lemoine

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)

Abstract

We consider two techniques of in-band frequency domain multiplexed (FDM) pilots using interleaved frequency domain multiple access (IFDMA) signal with a Chu sequence for DFT-precoded OFDM (or single-carrier (SC)) systems. One, called frequency domain superimposed pilot technique (FDSPT), superimposes pilot tones onto scaled or deleted data tones, which preserves spectral efficiency at the expense of a slight performance loss. The other, called frequency expanding technique (FET), multiplexes pilot tones by displacing data tones, which slightly reduces spectral efficiency. Using FDM pilots in SC systems facilitates flexible and efficient assignment of signals to available spectrum. We propose an iterative frequency domain decision-directed interference cancellation technique to reduce the intersymbol interference level of SC signals with FDSPT pilots (resulting from the suppression of data tones). Moreover, we propose a low complexity frequency domain iterative decisiondirected channel estimation (IDDCE) technique for SC systems using FDM pilots. Using IDDCE, the frame error rate (FER) performance for coded SC systems using FET and FDSPT pilots with interference cancellation is found to be about 0.2 dB and about 0.5 dB, respectively, away from the FER performance with known channel frequency response at FER=10-2. FDSPT pilots can also be used for OFDM systems with channel coding. It is found that an extra 1 dB of SNR is required at FER=10-2, compared with that using the conventional FET pilots for OFDM systems.

Original languageEnglish
Pages (from-to)348-358
Number of pages11
JournalIEEE Journal on Selected Areas in Communications
Volume26
Issue number2
DOIs
Publication statusPublished - Feb 2008
Externally publishedYes

Keywords

  • DFTprecoded OFDM
  • Frequency domain channel estimation
  • In-band pilots
  • Iterative frequency domain equalization
  • OFDM
  • Single-carrier

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