OFDMA Uplink Channel Prediction to Enable
Frequency-adaptive Multiuser Scheduling.
, Uppsala University.
European Signal Processing Conference Eusipco 2007,
Poznan, Poland, September 2007.
Frequency-adaptive multiuser scheduling utilizes the
frequency-selective small-scale fading to
allocate subcarriers with
advantageous signal-to-noise ratio to each user.
Due to channel
time-variability and delays of the transmission control loop,
this will in general require channel prediction.
Division Duplex) uplinks pose the most challenging prediction
problem: All sub-bands that may potentially
be allocated must here be
predicted for all involved user terminals, based on pilots
transmitted from all terminals.
This poses challenges with respect
to prediction accuracy, estimator complexity and
This paper explores the design
of Kalman predictors used for uplink prediction,
in the context of the EU WINNER project baseline
The paper investigates how the performance depends
on the type of pilots that are transmitted from each terminal.
The conclusion is that for frequency-selective channels,
the use of overlapping pilots outperforms schemes
where each user places pilots on
exclusive time-frequency symbols.
Another conclusion is that cycling the pilot patterns in time
improves the performance.
Channel prediction in an environment with flat Doppler
spectrum is also evaluated.
The resulting performance is adequate for use at
vehicular velocities at 3-5 GHz carriers.
PIMRC 2007 on other aspects such as
the computational complexity of the predictor.
IST Mobile Summit 2005 paper
that describes adaptive TDMA/OFDMA downlink and
Channel estimation and prediction
from a Bayesian perspective,
Licenciat Thesis by Daniel Aronsson, 2007.
IEEE ICASSP 2005:
Channel estimation and prediction for adaptive
OFDMA/TDMA uplinks based on overlapping pilots.
Channel estimation and prediction for adaptive OFDM
Prediction of mobile radio channels,
Ph.D. Thesis by Torbjörn Ekman 2002.
Proceedings of the IEEE
paper (2007) giving overview of adaptive
transmission in OFDMA systems.
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