Title of Invention

METHOD AND A RECEIVER IN A COMMUNICATION SYSTEM FOR DEMODULATING A MODULATION SYMBOL WITHOUT KNOWLEDGE OF THE MODULATION CONSTELLATION EMPLOYED IN A TRANSMITTER TO MODULATE THE SYMBOL BEFORE TRANSMISSION

Abstract A method of demodulating a modulation symbol in a receiver of a communication system without knowledge of the modulation constellation employed in a transmitter to modulate the symbol before transmission, comprising the steps of demodulating the symbol according to an assumed modulation constellation, interpreting the modulation symbol as a symbol of one of a family of hierarchical modulation constellations, decoding the demodulated symbol using a forward error correction (FEC) technique, checking the decoded symbol for correctness, wherein during the interpretation step Mmax -ks of the symbol bits are applied to the FEC decoder where Mmax denotes the number of symbol bits of highest order modulation constellation, Ms is the number of symbol bits of the respective assumed modulation constellation and ks is a value which varies for each assumed modulation constellation according to ks = Mmax -Ms.
Full Text

modulation symbol is useful for mapping the symbol bits into a signal constellation diagram containing a plurality of regions defined by decision boundaries for each bit.
According to a further preferred embodiment of the method, the steps of interpreting and demodulating are successively repeated, wherein in each iteration the modulation symbol is interpreted as a symbol of a different one of the plurality of possible modulation constellations. Hence, the method repeats the steps of interpreting and demodulating until the correct demodulated symbol is obtained. The corresponding embodiment of the receiver underlying the invention contains a feedback loop for notifying the interpretation unit on the result of the check for correctness.
According to a variant of the method underlying the invention, the steps of interpreting and demodulating are carried out simultaneously for a plurality of different possible modulation constellations. Further, the demodulated symbols are selected depending on the result of the check for correctness. In the corresponding preferred embodiment of the receiver, the means for interpreting and demodulating are arranged in parallel branches in order to allow the simultaneous processing. According to this embodiment, although hardware complexity is increased, the advantage lies in the fact that correct demodulated symbols are obtained very quickly.
According to a further advantageous embodiment of the method, the modulation constellations are of different order and the repetition of the interpretation and demodulation steps are performed in a descending modulation order. Alternatively, the repetition can be based on the preceding successful modulation constellation which provided correct demodulated symbols.

Accordingly, the present invention provides a method of demodulating a modulation symbol in a receiver of a communication system without knowledge of the modulation constellation employed in a transmitter to modulate the symbol before transmission, comprising the steps of demodulating the symbol according to an assumed modulation constellation, interpreting the modulation symbol as a symbol of one of a family of hierarchical modulation constellations, decoding the demodulated symbol using a forward error correction (FEC) technique, checking the decoded symbol for correctness, wherein during the interpretation step Mmax - ks of the symbol bits are applied to the FEC decoder where Max denotes the number of symbol bits of highest order modulation constellation, Ms is the number of symbol bits of the respective assumed modulation constellation and kg is a value which varies for each assumed modulation constellation according to ks= Mmax - Ms-
The present invention also provides a receiver in a communication system for demodulating a modulation symbol without knowledge of the modulation constellation employed in a transmitter to modulate the symbol prior to transmission, comprising a demodulator (21) for demodulating the symbol according to an assumed modulation constellation, and an interpretation unit
(22) for interpreting the modulation symbol as a symbol of one of a family of hierarchical modulation constellations,a forward error correction (FEC) decoder
(23) for decoding Mmax - K hits of the demodulated symbol, where Mmax denotes the number of symbol bits of highest order modulation constellation Mg is the number of symbol bits of the respective assumed modulation constellation, and kg is a value which varies for each assumed modulation constellation according to ks = Mmax - Mg, and means (24) for checking the demodulated symbol for correctness.

In the following preferred embodiments of the present invention are described in further detail in order to facilitate the understanding of the invention with reference to the accompanying drawings-Figures 1-4 shows examples of QAM signal constellation diagrams in the complex signal plane.


WE CLAIM :
1. A method of demodulating a modulation symbol in a receiver of a communication system without knowledge of the modulation constellation employed in a transmitter to modulate the symbol before transmission, comprising the steps of demodulating the symbol according to an assumed modulation constellation, interpreting the modulation symbol as a symbol of one of a family of hierarchical modulation constellations, decoding the demodulated symbol using a forward error correction (FEC) technique, checking the decoded symbol for correctness, wherein during the interpretation step Mmax - ks of the symbol bits are applied to the FEC decoder where Mmax denotes the number of symbol bits of highest order modulation constellation, Ms is the number of symbol bits of the respective assumed modulation constellation and kg is a value which varies for each assumed modulation constellation according to ks=Mmax-Ms.
2. The method according to claim 1, wherein the step of checking the demodulated symbol for correctness is performed using the FEC technique.
3. The method according to claim 1, wherein the step of checking the demodulated symbol for correctness is performed by a CRC detection unit.
4. The method according to claim 1, wherein the modulation symbol is

constituted by a structure S0... SM-I of an M-tuple of symbol bits and the plurality of 2M modulation symbols form the modulation constellation of a particular order.
5. The method according to claim 1, wherein the interpretation step is successively repeated, wherein in each iteration the modulated symbol is interpreted as a symbol of a different one of the plurality of possible modulation constellations.
6. The method according to claim 5, wherein the repeated interpretation step is performed for modulation constellations of descending modulation order and/or are based on a previous successful modulation constellation which provided correct demodulated symbols.
7. The method according to claim 1, wherein the interpretation step is carried out simultaneously for a plurality of different possible modulation constellations and further comprising the step of selecting the demodulated symbols depending on the result of the check for correctness.
8. The method according to claim 1, wherein during the interpretation step Mmax- ks of symbol bits are stored in a buffer before being applied to the FEC decoder.
9. The method according to claim 1, wherein during the demodulation step the received symbol is assumed to be of the highest order modulation constellation representing Mmax symbol bits.

10. A receiver in a communication system for demodulating a modulation symbol without knowledge of the modulation constellation employed in a transmitter to modulate the symbol prior to transmission, comprising a demodulator (21) for demodulating the symbol according to an assumed modulation constellation, and an interpretation unit (22) for interpreting the modulation symbol as a symbol of one of a family of hierarchical modulation constellations, a forward error correction (FEC) decoder (23) for decoding Mmax - K, bits of the demodulated symbol, where Mmax denotes the number of symbol bits of highest order modulation constellation Ms is the number of symbol bits of the respective assumed modulation constellation, and kg is a value which varies for each assumed modulation constellation according to kg = Mmax - Ms, and means (24) for checking the demodulated symbol for correctness.
11. The receiver according to claim 10, wherein the FEC decoder (23) is adapted to check the decoded symbol for correctness.
12. The receiver according to claim 10, wherein a CRC detection unit (24) is provided for checking the demodulated symbol for correctness.
13. The receiver according to claim 10, wherein a feedback loop (25) is provided for notifying the interpretation unit (22) on the result for check for correctness.
14. The receiver according to claim 10, wherein a plurality of interpretation units (22-1, 22-2,..22-n), FEC decoders (23-1, 23-2,.,23-n) and means (24-1,24-2,..24-n) are provided for checking the demodulated symbol for

correctness arranged in parallel branches to demodulate the symbols simultaneously for a plurality of different possible modulation constellations.
15. The receiver according to claim 10, wherein the interpretation unit (22)
comprises a buffer for storing and Mmax - ks symbol bits.
16. A method of demodulating a modulation symbol in a receiver of a
communication system without knowledge of the modulation
constellation employed in a transmitter to modulate the symbol before
transmission substantially as herein described with reference to the
accompanying drawings.
17. A receiver in a communication system for demodulating a modulation
symbol without knowledge of the modulation constellation employed in a
transmitter to modulate the symbol prior to transmission substantially as
herein described with reference to the accompanying drawings.
Dated this 7 day of November 2002


Documents:

in-pct-2002-1824-che- triplecate claims.pdf

in-pct-2002-che-1824-claims duplicate.pdf

in-pct-2002-che-1824-claims original.pdf

in-pct-2002-che-1824-correspondance others.pdf

in-pct-2002-che-1824-correspondance po.pdf

in-pct-2002-che-1824-description complete duplicate.pdf

in-pct-2002-che-1824-description complete original.pdf

in-pct-2002-che-1824-drawings.pdf

in-pct-2002-che-1824-form 1.pdf

in-pct-2002-che-1824-form 19.pdf

in-pct-2002-che-1824-form 26.pdf

in-pct-2002-che-1824-form 3.pdf

in-pct-2002-che-1824-form 5.pdf

in-pct-2002-che-1824-pct.pdf


Patent Number 204233
Indian Patent Application Number IN/PCT/2002/1824/CHE
PG Journal Number 26/2007
Publication Date 29-Jun-2007
Grant Date 13-Feb-2007
Date of Filing 07-Nov-2002
Name of Patentee MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD
Applicant Address 1006, Oaza Kadoma, Kadoma-shi Osaka 571.
Inventors:
# Inventor's Name Inventor's Address
1 GOLITSCHEK EDLER VON ELBWART, Alexander Wilhelminenstrasse 32 64285 Darmstadt.
2 SEIDEL, Eiko Gruener Weg 1 64283 Darmstadt.
PCT International Classification Number H04L27/00
PCT International Application Number PCT/EP2001/002813
PCT International Filing date 2001-03-13
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 01921329.7 2001-03-13 EUROPEAN UNION