Method and system for blind detection of modulation type

• US 20030166395A1
• Filed: 04/08/2003
• Published: 09/04/2003
• Est. Priority Date: 03/13/2001
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Seidel, Eiko, Golitschek Edler Von Elbwart, Alexander
• Granted Patent: US 7,046,975 B2
• Time in Patent Office: Days
• US Class Current: 455/130
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 27/2017 in which the phase changes are non-linear, e.g. generalized and Gaussian minimum shift keying, tamed frequency modulation H04L27/201 takes precedence
• CPC Class Codes: H04L 27/2067 with more than two phase states H04L27/2064 takes precedence
• CPC Class Codes: H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems

Abstract

The invention relates to a method and a receiver for demodulating a modulation symbol in a communication system without knowledge of the modulation constellation employed in a transmitter to modulate this symbol before transmission. According to the method, the invention comprises the steps of 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 and demodulating the symbol according to the assumed modulation constellation. Finally, the demodulated symbol is checked for correctness. The receiver comprises of a corresponding interpretation unit, a demodulator and an FEC decoder as well as means for checking the correctness of the demodulated symbol.

Claims

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:

interpreting the modulation symbol as a symbol of one of a family of hierarchical modulation constellations,

demodulating the symbol according to the assumed modulation constellation,

decoding the demodulated symbol using a forward error correction (FEC) technique, and

checking the decoded symbol for correctness.

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 one of claims 1-3, wherein the modulation symbol is constituted by a structure S₀ . . . S_M−

1 of an M-tuple of symbol bits and the plurality of 2^M modulation symbols form the modulation constellation of a particular order.

5. The method according to one of claims 1-4, wherein the interpretation step and the demodulation step are 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 and demodulation steps are performed for modulation constellations of descending modulation order and/or are based on a previous successful modulation constellation which provided correct demodulated symbols.

8. The method according to one of claims 1-7, wherein during the interpretation step M_max−

k_s of symbol bits are stored in a buffer before being applied to the FEC decoder, where M_max denotes the number of symbol bits of highest order modulation constellation, M_s is the number of symbol bits of the respective assumed modulation constellation and k_s is a value which varies for each assumed modulation constellation according to k_s=M_max−

M_s.

9. 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:

an interpretation unit (22) for interpreting the modulation symbol as a symbol of one of a family of hierarchical modulation constellations,

a demodulator (21) for demodulating the symbol according to the assumed modulation constellation, and

a forward error correction (FEC) decoder (23) for decoding the demodulated symbol, and

means (24) for checking the demodulated symbol for correctness.

7. The method according to one of claims 14, wherein the interpretation step and the demodulation step are 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.

10. The receiver according to claim 9, wherein the FEC decoder (23) is adapted to check the decoded symbol for correctness.

11. A receiver according to claim 9, further comprising a CRC detection unit (24) for checking the demodulated symbol for correctness.

12. The receiver according to one of claim 9-11, further comprising a feedback loop (25) for notifying the interpretation unit (22) on the result for check for correctness.

13. The receiver according to one of claims 9-11, comprising 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) for checking the demodulated symbol for correctness arranged in parallel branches to demodulate the symbols simultaneously for a plurality of different possible modulation constellations.

14. The receiver according to one of claims 9-13, wherein the interpretation unit (22) comprises a buffer for storing and M_max−

k_s symbol bits, where M_max denotes the number of symbol bits of highest order modulation constellation M_s is the number of symbol bits of the respective assumed modulation constellation, and k_s is a value which varies for each assumed modulation constellation according to k_s=M_max−

M_s.