Low-Complexity Block Turbo Equalization for OFDM Systems in Time-Varying Channels

  • Authors:
  • Kun Fang;L. Rugini;G. Leus

  • Affiliations:
  • Fac. of Electr. Eng., Math. & Comput. Sci. (EEMCS),, Delft Univ. of Technol., Delft;-;-

  • Venue:
  • IEEE Transactions on Signal Processing
  • Year:
  • 2008

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Abstract

We propose low-complexity block turbo equalizers for orthogonal frequency-division multiplexing (OFDM) systems in time-varying channels. The presented work is based on a soft minimum mean-squared error (MMSE) block linear equalizer (BLE) that exploits the banded structure of the frequency-domain channel matrix, as well as a receiver window that enforces this banded structure. This equalization approach allows us to implement the proposed designs with a complexity that is only linear in the number of subcarriers. Three block turbo equalizers are discussed: two are based on a biased MMSE criterion, while the third is based on the unbiased MMSE criterion. Simulation results show that the proposed iterative MMSE BLE achieves a better bit error rate (BER) performance than a previously proposed iterative MMSE serial linear equalizer (SLE). The proposed equalization algorithms are also tested in the presence of channel estimation errors.