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Channel Estimation and Prediction for Adaptive OFDMA/TDMA Uplinks
based on Overlapping Pilots.
Mikael Sternad
and
Daniel Aronsson,
Uppsala University
IEEE International Conference on
Acoustics, Speech and Signal Processing, ICASSP-05,
Philadelphia, PA, March 2005. © IEEE
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Outline:
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The Swedish Wireless IP project studies
problems that are crucial in the evolution of UMTS towards high
data rates, as well as in future 4G technologies aimed at
rapidly mobile terminals. The goal is to attain higher
throughputs for packet data in particular in downlinks,
without unnecessary
bandwidth expansion and while providing acceptable
quality of service for various classes of traffic.
This research is also performed within the
EU Integrated Project WINNER.
At IEEE VTC-Fall 2003, we presented our
concept for an adaptive OFDM downlink
in four interrelated papers (see links below).
This paper discussed how to perform
channel estimation in the
corresponding uplinks.
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Abstract:
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In adaptive wireless packet transmission for multiple users,
resources are allocated based on measurement and feedback of the
channel qualities. Uplink channels of adaptive OFDM systems that
use FDD have to be estimated and predicted based on uplink pilots
transmitted by all active users.
To prevent a prohibitive pilot
overhead, the use of overlapping (simultaneously transmitted)
pilots is considered here. Kalman estimators and predictors can
efficiently utilize the channel correlation in time and frequency
to obtain estimates.
The estimates have higher error than in the
downlink case where overlapping pilots are not needed. However,
the estimation and prediction MSE increases rather slowly with the
number of simultaneous users. The results indicate that the
accuracy is adequate for control of an adaptive transmission loop.
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Related publications:
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Channel estimation
and prediction from a Bayesian perspective
Licenciate Thesis by Daniel Aronsson, 2007.
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Proc. of the IEEE (Dec. 2007)
invited paper on
adaptive transmission in beyond-3G wireless systems.
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PIMRC 2007,
later results on uplink OFDMA channel prediction.
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Eusipco 2007,
later results on uplink OFDMA channel prediction.
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Paper 1 at VTC2003,
on adaptive modulation, multiuser diversity
and channel variability within bins.
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Paper 2 at VTC2003,
on the OFDM downlink and cell planning for high SIR.
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Paper 3 at VTC2003,
on OFDM downlink channel estimation and channel prediction.
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Paper 4 at VTC2003,
on the impact of prediction errors on the adaptive modulation.
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An earlier paper
(WWRF 2002) on adaptive uplinks.
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An overview of the Wireless IP Project (RVK02)
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Channel Power Prediction,
by using unbiased predictors and
advanced regressor noise reduction (VTC 2002-Fall).
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PhD Thesis on channel prediction,
by Torbjörn Ekman.
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Source:
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Pdf, (101K)
Postscript (79K)
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The Wireless IP Project Homepage
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Main
entry in list of publications
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