Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1998-06-09
2001-10-09
DeCady, Albert (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
Reexamination Certificate
active
06301683
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a trellis encoding technique for PCM modems. Even more particularly, this invention relates to a novel trellis encoding technique which is based upon International Telecommunication Union (ITU) Standard V.34, a copy of which is attached as an appendix to this application, and is to be considered an integral part thereof. The trellis encoding technique described in V.34 is based upon a trellis coding method and arrangement disclosed in U.S. Pat. No. 4,941,154, incorporated herein by reference.
BACKGROUND OF THE INVENTION
The use of trellis encoding has provided substantial advantages in digital communication. The use of trellis encoding on the analog downstream channel of PCM modems should provide similar advantages. Unfortunately, the non-equal spacing of PCM symbols results in the errors being concentrated only in those symbols with small adjacent symbol spacing.
This unequal distribution of symbol errors per symbol spacing reduces the advantages of trellis encoding. The throughput loss of including trellis state information can be compensated by an increase of throughput due to the ability to communicate error-free in a higher noise environment. Also, the use of trellis encoding may not be compatible with the variety of transmit gain and spectral shaping proposed by others.
What is needed is a trellis encoding technique which uses a modified V.34 trellis encoding for use with the analog downstream of PCM modems.
SUMMARY OF THE INVENTION
A method of applying a multidimensional error reduction/correction algorithm on a stream of one dimensional symbols, comprising converting the stream of one dimensional symbols into a corresponding stream of two dimensional symbols; and, applying the multidimensional error reduction/correction algorithm to the stream of two dimensional symbols. The invention also provides a method of normalizing a metric used by an error reduction/correction algorithm on a stream of symbols wherein the symbols are non-uniformly spaced, comprising: determining a minimum distance (dmin) between two closest symbols in the stream, for each symbol in the stream, determining a minimum distance (dsym) between the each symbol in the stream and each of its adjacent neighboring symbols, and, normalizing the metric used by the error reduction/correction algorithm by the ratio dmin/dsym.
REFERENCES:
patent: 4933956 (1990-06-01), Forney, Jr.
patent: 4941154 (1990-07-01), Wei
patent: 4980897 (1990-12-01), Decker et al.
patent: 5119403 (1992-06-01), Krishnan
patent: 5150381 (1992-09-01), Forney, Jr. et al.
patent: 5233629 (1993-08-01), Paik et al.
patent: 5249200 (1993-09-01), Chen et al.
patent: 5251236 (1993-10-01), Brehmer et al.
patent: 5295142 (1994-03-01), Hatakeyama
patent: 5321725 (1994-06-01), Paik et al.
patent: 5363408 (1994-11-01), Paik et al.
patent: 5396519 (1995-03-01), Betts et al.
patent: 5398073 (1995-03-01), Wei
patent: 5504479 (1996-04-01), Doyle et al.
patent: 5559835 (1996-09-01), Betts
patent: 5659578 (1997-08-01), Alamouti et al.
patent: 5706312 (1998-01-01), Wei
patent: 5790570 (1998-08-01), Heegard et al.
patent: 5878077 (1999-03-01), Betts
patent: 5926505 (1999-07-01), Long
patent: 5953376 (1999-09-01), Wei
patent: 5995550 (1999-11-01), Xu et al.
patent: 6005898 (1999-12-01), Kaewell, Jr.
Kaminsky et al (An eight-dimensional phase invariant trellis coded modulation scheme with constant envelope; IEEE; Apr. 10, 1991).*
Kaminsky et al Constant envelope eight-dimensional trellis coded modulation schemes; IEEE; Jun. 26, 1991).*
Calderbank et al (The normalized second moment of the binary lattice determined by a convolutional code; IEEE; Jan. 1994).*
Chame: A Digital Signal Processor Yields Enhanced Data/FAX Pump, IEEE, 1997.*
Rossin, et al., On the Symmetries and Structures of Trellis Codes, IEEE, 1994.
De'cady Albert
Foley & Lardner
Lamarre Guy
Vocal Technologies Ltd.
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