MMSE beamforming for SC-FDMA transmission over MIMO ISI channels

  • Authors:

  • Uyen Ly Dang;Michael A. Ruder;Robert Schober;Wolfgang H. Gerstacker

  • Affiliations:

  • Institute of Mobile Communications, University of Erlangen-Nürnberg, Cauerstraße 7, Erlangen, Germany;Institute of Mobile Communications, University of Erlangen-Nürnberg, Cauerstraße 7, Erlangen, Germany;Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, Canada;Institute of Mobile Communications, University of Erlangen-Nürnberg, Cauerstraße 7, Erlangen, Germany

  • Venue:
  • EURASIP Journal on Advances in Signal Processing - Special issue on advances in single carrier block modulation with frequency domain processing
  • Year:
  • 2011

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Abstract

We consider transmit beamforming for single-carrier frequency-division multiple access (SC-FDMA) transmission over frequency-selective multiple-input multiple-output (MIMO) channels. The beamforming filters are optimized for minimization of the sum of the mean-squared errors (MSEs) of the transmitted data streams after MIMO minimum mean-squared error linear equalization (MMSE-LE), and for minimization of the product of the MSEs after MIMO MMSE decision-feedback equalization (MMSE-DFE), respectively. We prove that for SC-FDMA transmission in both cases eigenbeamforming, diagonalizing the overall channel, together with a nonuniform power distribution is the optimum beamforming strategy. The optimum power allocation derived for MMSE-LE is similar in spirit to classical results for the optimum continuous-time transmit filter for linear modulation formats obtained by Berger/Tufts and Yang/Roy, whereas for MMSE-DFE the capacity achieving waterfilling strategy well known from conventional single-carrier transmission schemes is obtained. Moreover, we present a modification of the beamformer design to mitigate an increase of the peak-to-average power ratio (PAPR) which is in general associated with beamforming. Simulation results demonstrate the high performance of the proposed beamforming algorithms.