Spatio-Temporal Equalization for Multipath Environments
in Mobile Radio Applications
IEEE Vehicular Technology Conference,
Chicago, IL, July 26-28, 1995. © 1995 IEEE.
When digital data are transmitted over multipath radio channels,
the use of base station receivers with multiple antenna elements
can improve the performance significantly, if the measurements
are combined in an appropriate way. The paper studies
ways to perform this combination in TDMA systems.
A key problem is that a large number of filter coefficients
may have to be adjusted based on short training sequences.
Combined spatial and temporal equalization using an
antenna array combined with a decision feedback equalization
scheme is investigated. In particular a TDMA type system,
with a relatively short training sequence, is considered.
Three algorithms are introduced.
The first two algorithms are based on indirect schemes, where
the channels to each
receiver antenna element are identified. The identified channels and
the correlations of the residuals are then used for the tuning
of the beamformer/equalizer coefficients. The spatio-temporal
correlations of the residuals are used in the first algorithm while in
the second algorithm only the spatial correlations of the residuals
The third algorithm forms a number of beams by
using mixtures of different delayed versions of the training
sequence as reference signals. It then performs
temporal equalization by combining the outputs
from the different beamformers, with appropriate delays.
This latter algorithm requires less computations for the
tuning of the equalizer, at the expense of a performance degradation in
The algorithms are evaluated with simulations of multipath
scenarios involving co-channel interference.
- Related publications:
PhD Thesis by Erik Lindskog.
by E Lindskog 1995, which includes the paper.
Conference paper in IEEE ICASSP'95,
which investigates related algorithms.
In Postscript :
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