Pulse or digital communications – Testing – With indicator
Reexamination Certificate
1997-12-23
2001-11-20
Pham, Chi (Department: 2631)
Pulse or digital communications
Testing
With indicator
C375S229000
Reexamination Certificate
active
06320902
ABSTRACT:
This invention relates to digital subscriber loop telecommunications systems and, in particular, to channel equalizers for the same.
BACKGROUND OF THE INVENTION
The current asymmetrical digital subscriber line (ADSL) standard is based on discrete multi-tone signalling (DMIT) protocol, wherein each frame is comprised of the IFFT of a number of samples. In ADSL channels, and at such high data rates, it is computationally expensive to fully equalize the channel. Hence, only partial equalization is implemented to constrain the overall effective channel length to a certain number of samples, say v. Then the last v samples of each frame are used as a prefex to the frame, so that in effect the time domain data is chclically convolved with effective overall channel response, composed of the physical channel and the equalizer.
FIG. 1
shows the overall situation.
The current equalization technique, which relies on frequency domain 1 ms (least mean square) is computationally expensive, is nonlinear, and its steady state error is light.
SUMMARY OF THE INVENTION
The invention provides an equalization technique that relies on time domain lms, has lower computational complexity and has lower steady state error.
REFERENCES:
patent: 3997841 (1976-12-01), Borowski
patent: 5285474 (1994-02-01), Chow et al.
Nafie Mohammed
Wu Song
Brady III Wade James
Burd Kevin M
Franz Warren L.
Pham Chi
Telecky , Jr. Frederick J.
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