Method to create hierarchical modulation in OFDM

• US 20050141627A1
• Filed: 11/22/2004
• Published: 06/30/2005
• Est. Priority Date: 11/26/2003
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG, Stefan V. Chmielewski
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Dibiaso, Eric A., Walker, Glenn A., Hiatt, Michael L. Jr.
• Granted Patent: US 7,230,992 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04H 20/28 Arrangements for simultaneous broadcast of plural pieces of information
• CPC Class Codes: H04H 20/42 Arrangements for resource management
• CPC Class Codes: H04H 20/51 specially adapted for satellite broadcast systems
• CPC Class Codes: H04H 20/74 of satellite networks
• CPC Class Codes: H04H 40/90 specially adapted for satellite broadcast receiving
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 1/0066 Parallel concatenated codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/208 involving signal re-encoding
• CPC Class Codes: H04L 27/183 Multiresolution systems
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/3488 Multiresolution systems

Abstract

The present invention involves a method for transmitting data using an orthogonal frequency division multiplex (OFDM) transmission system, such as over a terrestrial network used in satellite digital audio radio. A OFDM signal is generated based on first input data. A variation is introduced in the OFDM signal based on second input data to generate a modified OFDM signal which is transmitted. The modified OFDM signal is decoded by performing a demodulation of the modified OFDM signal then a first and second detection to obtain the first input data and the second input data. The introduction of a variance may include introducing an additional phase offset across adjacent OFDM sub-carriers, across adjacent OFDM symbols, an additional phase offset in the OFDM signal, an additional amplitude offset in the OFDM signal, an additional amplitude augmentation in the OFDM signal, and/or a second variation in the first OFDM signal based on third input data.

Claims

1. A method for transmitting data using an orthogonal frequency division multiplex (OFDM) transmission system comprising the steps of:

generating a first OFDM signal based on first input data;

introducing a variation in the first OFDM signal based on second input data to generate a modified OFDM signal;

transmitting the modified OFDM signal;

decoding the modified OFDM signal by performing a demodulation of the modified OFDM signal then a first and second detection to obtain the first input data and the second input data.

2. The method of claim 1 wherein the transmitting step includes transmitting the modified OFDM signal with a terrestrial repeater in a satellite based system.

3. The method of claim 1 wherein the introducing step includes introducing the additional phase offset across adjacent OFDM sub-carriers.

4. The method of claim 1 wherein the introducing step includes introducing the additional phase offset across adjacent OFDM symbols.

5. The method of claim 1 wherein the introducing step uses an additional phase offset as the variation in the first OFDM signal.

6. The method of claim 1 wherein the introducing step uses an additional amplitude offset as the variation in the first OFDM signal.

7. The method of claim 1 wherein the introducing step uses an additional amplitude augmentation as the variation in the first OFDM signal.

8. The method of claim 1 wherein the introducing step includes introducing a second variation in the first OFDM signal based on third input data.

9. The method of claim 1 wherein the decoding step includes using an iterative decoder to obtain the second input data.

10. The method of claim 9 wherein the decoding step further includes the iterative decoder using an a posterior algorithm.

11. The method of claim 1 wherein the decoding step includes using a legacy decoder to obtain the first input data.

12. A receiver for receiving primary and secondary data from an orthogonal frequency division multiplex (OFDM) signal comprising:

an antenna for receiving RF signals;

a demodulator coupled to said antenna for downconverting received RF signals into an OFDM signal;

a first detector coupled to said demodulator, said first detector having a first output, and said first detector being adapted to detect primary data on the OFDM signal; and

a second detector coupled to said demodulator, said second detector having a second output, and said second detector being adapted to detect secondary data as predetermined variations on the OFDM signal.

13. The receiver of claim 12 wherein said antenna is adapted to receive satellite broadcast signals.

14. The receiver of claim 12 wherein said second detector is adapted to detect an additional phase offset across adjacent OFDM sub-carriers.

15. The receiver of claim 12 wherein said second detector is adapted to detect an additional phase offset across adjacent OFDM symbols.

16. The receiver of claim 12 wherein said second detector is adapted to detect an additional phase offset as the variation in the first OFDM signal.

17. The receiver of claim 12 wherein said second detector is adapted to detect an additional amplitude offset as the variation in the first OFDM signal.

18. The receiver of claim 12 wherein said second detector is adapted to detect an additional amplitude augmentation as the variation in the first OFDM signal.

19. The receiver of claim 12 further comprising a third detector adapted to detect a second variation in the first OFDM signal based on third input data.

20. The receiver of claim 12 wherein said second detector includes an iterative decoder.

21. The receiver of claim 20 wherein said iterative decoder uses an a posterior algorithm with an interleaver to detect the primary and secondary data.

22. A transmitter for transmitting primary and secondary data on an OFDM signal comprising:

an encoder adapted to receive a first and second input data, said encoder capable of providing digital information based on a first level of data on an output stream as an OFDM signal, said encoder capable of providing digital information based on a second level of data as a variance of the OFDM signal on the output stream;

a modulator coupled to said encoder for upconverting said output stream; and

an antenna coupled to said modulator for transmitting RF signals based on the upconverted output stream.

23. The transmitter of claim 22 wherein said antenna is adapted to broadcast the modified OFDM signal as a terrestrial repeater in a satellite based system.

24. The transmitter of claim 22 wherein said encoder is adapted to impose an additional phase offset across adjacent OFDM sub-carriers.

25. The transmitter of claim 22 wherein said encoder is adapted to impose an additional phase offset across adjacent OFDM symbols.

26. The transmitter of claim 22 wherein said encoder is adapted to impose an additional phase offset as the variation in the OFDM signal.

27. The transmitter of claim 22 wherein said encoder is adapted to impose an additional amplitude offset as the variation in the OFDM signal.

28. The transmitter of claim 22 wherein said encoder is adapted to impose an additional amplitude augmentation as the variation in the first OFDM signal.

29. The transmitter of claim 22 wherein said encoder is adapted to impose a second variation in the OFDM signal based on third input data.

30. The transmitter of claim 22 wherein said encoder includes a recursive systematic code encoder.

31. The transmitter of claim 22 wherein said encoder includes an interleaver adapted to receive the first and second input data.

32. The transmitter of claim 31 further including a multiplexer adapted to provide parity data output.