Method to create hierarchical modulation in OFDM

• US 7,230,992 B2
• Filed: 11/22/2004
• Issued: 06/12/2007
• Est. Priority Date: 11/26/2003
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG (Aptiv PLC), Stefan V. Chmielewski
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Walker, Glenn A., Dibiaso, Eric A., Hiatt, Jr., Michael L.
• Primary Examiner(s): PHU, PHUONG M
• Application Number:
  US10/995,946
• Publication Number:
  US 20050141627A1
• Time in Patent Office: 932 Days
• Field of Search: 375/260, 375/341, 375/261, 370/207, 370/232, 455/562.1
• 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 OFDM sub-carriers using differential modulation based on first input data;

hierarchically modulating the OFDM sub-carriers based on second input data to generate a hierarchically modulated differential OFDM signal;

transmitting the hierarchically modulated differential OFDM signal;

hierarchically demodulating and decoding the hierarchically modulated differential OFDM signal by performing a demodulation of the hierarchically modulated differential 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 hierarchically modulated differential OFDM signal with a terrestrial repeater in a satellite based system.

3. The method of claim 1 wherein the hierarchically modulating step includes introducing an additional phase offset based on the second input data across adjacent OFDM sub-carriers.

4. The method of claim 1 wherein the hierarchically modulating step includes introducing an additional phase offset based on the second input data across adjacent OFDM symbols.

5. The method of claim 1 wherein the hierarchically modulating step includes introducing an additional amplitude offset based on the second data across one of (1) adjacent OFDM sub-carriers and (2) adjacent OFDM symbols.

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

7. The method of claim 6 wherein the decoding step further includes the iterative decoder using an a posterior algorithm.

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

16. The method of claim 1 wherein the hierarchical modulation step includes a second differential modulation based on the second input data.

17. The method of claim 1 wherein the hierarchical modulation step includes a coherent modulation based on the second input data.

9. A receiver for receiving primary and secondary data from a hierarchically modulated differential orthogonal frequency division multiplex (OFDM) signal comprising:

an antenna for receiving RF signals;

a demodulator coupled to said antenna for hierarchically demodulating received RF signals comprising hierarchically modulated differential OFDM signals into a downconverted differential 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 downconverted differential 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 variations on the downconverted differential OFDM signal.

10. The receiver of claim 9 wherein said antenna is adapted to receive terrestrially retransmitted satellite broadcast signals.

11. The receiver of claim 9 wherein said second detector is adapted to detect an additional phase offset across adjacent OFDM sub-carriers and derive therefrom the secondary data.

12. The receiver of claim 9 wherein said second detector is adapted to detect an additional phase offset across adjacent OFDM symbols and derive therefrom the secondary data.

13. The receiver of claim 9 wherein said second detector is adapted to detect an additional amplitude offset across one of adjacent OFDM sub-carriers and adjacent OFDM symbols as the variation in the first OFDM signal and derive therefrom the secondary data.

14. The receiver of claim 9 wherein said second detector includes an iterative decoder.

15. The receiver of claim 14 wherein said iterative decoder uses an a posterior algorithm with an interleaver to detect the primary and secondary data.