EURASIP Journal on Applied Signal Processing
Volume 2004 (2004), Issue 5, Pages 605-612
doi:10.1155/S1110865704311054
Abstract
Multiple-input and multiple-output (MIMO) systems
formed by multiple transmit and receive antennas can improve
performance and increase capacity of wireless communication
systems. Diagonal Bell Laboratories Layered Space-Time (D-BLAST)
structure offers a low-complexity solution for realizing the
attractive capacity of MIMO systems. However, for broadband
wireless communications, channel is frequency-selective and
orthogonal frequency division multiplexing (OFDM) has to be used
with MIMO techniques to reduce system complexity. In this paper,
we investigate D-BLAST for MIMO-OFDM systems. We develop a
layerwise channel estimation algorithm which is robust to channel
variation by exploiting the characteristic of the D-BLAST
structure. Further improvement is made by subspace tracking to
considerably reduce the error floor. Simulation results show that
the layerwise estimators require 1 dB less signal-to-noise
ratio (SNR) than the traditional blockwise estimator for a word
error rate (WER) of 10−2 when Doppler frequency is
40 Hz. Among the layerwise estimators, the subspace-tracking
estimator provides a 0.8 dB gain for 10−2 WER with
200 Hz Doppler frequency compared with the DFT-based
estimator.