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Adaptive Trellis-Coded Modulation over
Predicted Flat Fading Channels.
Sorour Falahati,
Uppsala University,
Arne Svensson,
Chalmers U. of Technology,
Mikael Sternad,
Uppsala University and
Hong Mei
Uppsala University.
IEEE Vehicular Technology Conference VTC2003-Fall,
Orlando, FLA, Oct. 2003.
© IEEE
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Outline:
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The Wireless IP project within the PCC program 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
througputs for packet data in particular in downlinks,
without bandwidth expansion and while providing acceptable
quality of service for various classes of traffic.
At IEEE VTC-Fall 2003, we presented our
concept for an adaptive OFDM downlink
in four interrelated papers (see links below).
This is Paper 4 of the four papers.
It discusses how the statistics of channel
power prediction errors can be taken into account
in the optimization of adaptive modulation
schemes that use Trellis-coded M-QAM modulation (TCM)
and uncoded M-QAM modulation.
It discusses the impact of the channel prediction
on the modulation rate limits and on the resulting spectral
efficiency in a single user system.
Since the optimization is in this paper performed
under a bit error rate constraint, the modulation rate
limits are raised markedly when predicting into fading dips.
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Abstract:
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We consider the optimum design of an adaptive scheme
based on TCM and predicted CSI for flat
Rayleigh fading channels, intended for fast link adaptation.
The question of how to optimally adjust the data rate to
maximize the spectral efficiency, subject to a
BER constraint when imperfect CSI is taken into account, is answered.
An optimum solution based on the predicted SNR
and the prediction error variance is derived.
The performance of the adaptive TCM scheme is
illustrated by utilizing seven 4-D trellis codes based on the
International Telecommunications
Union s ITU-T V.34 modem standard.
The results indicate that the gain in spectral efficiency by
adaptive TCM is about 1-2 dB compared to adaptive uncoded
M-QAM, for most of average SNRs.
Finally, the performance of the adaptive
TCM and in particular, its loss at high
SNRs compared to adaptive uncoded M-QAM,
are investigated in detail.
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Related publications:
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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 channel estimation and channel prediction.
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An overview of the Wireless IP Project (RVK02)
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Proc. of the IEEE (Dec. 2007)
invited paper on
adaptive transmission in beyond-3G wireless systems.
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Channel Power Prediction,
by using unbiased predictors and advanced regressor noise reduction.
(VTC 2002-Fall.)
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Optimizing uncoded adaptive M-QAM ,
by taking the power prediction error into account (GlobeCom03).
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Optimizing uncoded adaptive M-QAM ,
(IEEE Trans. COM 2004).
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Source:
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Pdf, (328K)
Postscript (512K)
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The Wireless IP Project Homepage
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Main
entry in list of publications
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