Symbol-wise beamforming for co-channel interference reduction in MIMO-OFDM systems

  • Authors:

  • André Pollok;Nick Letzepis;William G. Cowley

  • Affiliations:

  • Institute for Telecommunications Research, University of South Australia, Mawson Lakes, SA, Australia;Institute for Telecommunications Research, University of South Australia, Mawson Lakes, SA, Australia;Institute for Telecommunications Research, University of South Australia, Mawson Lakes, SA, Australia

  • Venue:
  • GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
  • Year:
  • 2009

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Abstract

In communication systems that use orthogonal frequency-division multiplexing and multiple transmit and receive antennas, beamforming (BF) is conventionally carried out on a subcarrier basis. The computational requirements are high as dedicated discrete Fourier transform (DFT) processors are needed for each antenna. Considerable complexity reductions can be achieved by symbol-wise BF, which performs the transmit and receive BF operations in the time domain, and therefore requires only one DFT processor per terminal. In this paper, we investigate symbol-wise BF for the mitigation of co-channel interference on spatially correlated channels, which are modelled with the Kronecker model. We show analytically that symbolwise BF is the optimal BF scheme when the channel is frequency-flat or fully correlated, and present a novel iterative algorithm for the computation of the optimal antenna weights. Monte-Carlo simulations confirm that the relative performance loss of symbolwise BF becomes negligible when approaching full correlation.