Method and apparatus for minimizing co-channel interference by scrambling

• US 8,325,699 B2
• Filed: 01/22/2010
• Issued: 12/04/2012
• Est. Priority Date: 06/28/2004
• Status: Active Grant

• Current Assignee: DTVG Licensing, Inc. (AT&T, Inc.)
• Original Assignee: DTVG Licensing, Inc. (AT&T, Inc.)
• Inventors: Sun, Feng-Wen, Iyer, Lakshmi
• Primary Examiner(s): Moore, Jr., Michael J
• Application Number:
  US12/692,344
• Publication Number:
  US 20100128816A1
• Time in Patent Office: 1,047 Days
• Field of Search: None
• US Class Current: 370/342
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 7/1858 Arrangements for data transmission on the physical system, i.e. for data bit transmission between network components
• CPC Class Codes: H04J 13/102 Combining codes
• CPC Class Codes: H04J 13/16 Code allocation
• CPC Class Codes: H04W 72/0466 the resource being a scrambling code
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

An approach is provided for minimizing co-channel interference in a communication system is disclosed. Non-header portions of frames, which are transmitted over the communication system, are scrambled according to respective different scrambling sequences. The above arrangement is particularly suited to a digital satellite broadcast and interactive system.

Claims

1. A method for transmitting a plurality of signals in a communication system, each signal comprising a plurality of frames, wherein each frame in the plurality of frames comprises a header portion and a payload portion, comprising:

assigning a first scrambling sequence with a scrambler at a transmission station in the communications system to a first header portion of a first frame of a first signal; and

assigning a second scrambling sequence with the scrambler at the transmission station in the communications system to a second header portion of a second frame of a second signal, the second signal being different than the first signal, wherein the first scrambling sequence and the second scrambling sequence are based on seeds selected from one of Table A and Table B;

2. The method of claim 1, further comprising determining the seeds to minimize a worst cross-correlation condition between the first signal and the second signal.

3. The method of claim 1, wherein the header portion is used for at least one of acquiring carrier phase and acquiring carrier frequency.

4. The method of claim 1, wherein the header portion is used for at least one of tracking carrier phase and tracking carrier frequency.

5. The method of claim 1, wherein each frame in the plurality of frames further comprises a pilot sequence.

6. The method of claim 5, wherein the pilot sequence is used for at least one of acquiring carrier phase and acquiring carrier frequency.

7. The method of claim 5, wherein the pilot sequence is used for at least one of tracking carrier phase and tracking carrier frequency.

8. The method of claim 1, further comprising transmitting the signals according to a modulation scheme including Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 8 PSK, 16 Amplitude Phase Shift Keying (APSK), 32 APSK, and a high order Quadrature Amplitude Modulation (QAM).

9. The method of claim 1, further comprising modulating the first signal with a first modulation scheme and the second signal with a second modulation scheme.

10. The method of claim 1, wherein each frame further comprises information encoded according to a Low Density Parity Check (LDPC) coding scheme.

11. A method of receiving a plurality of signals in a communication system, each signal comprising a plurality of frames, wherein each frame in the plurality of frames comprises a header portion and a payload portion, comprising:

receiving the plurality of signals at a receiver;

descrambling a first signal at the receiver; and

descrambling a second signal at the receiver, wherein the first signal is scrambled with a first scrambling sequence applied to a first plurality of frames of the first signal, and the second signal is scrambled with a second scrambling sequence applied to a second plurality of frames of the second signal, wherein the first scrambling sequence and the second scrambling sequence are based on seeds selected from one of Table A and Table B;

12. The method of claim 11, wherein each frame in the plurality of frames has a structure according to a Digital Video Broadcast (DVB) standard.

13. The method of claim 11, further comprising determining the seeds to minimize a worst cross-correlation condition between the first signal and the second signal.

14. The method of claim 11, further comprising transmitting the signals according to a modulation scheme including Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 8 PSK, 16 Amplitude Phase Shift Keying (APSK), 32 APSK, and a high order Quadrature Amplitude Modulation (QAM).

15. The method of claim 11, further comprising demodulating the first signal with a first demodulation scheme and the second signal with a second demodulation scheme.

16. The method of claim 11, wherein each frame further comprises information encoded according to a Low Density Parity Check (LDPC) coding scheme.

17. An apparatus for communicating in a radio communication system, comprising:

a receiver configured to receive a plurality of signals in a communication system, each signal comprising a plurality of frames, each frame in the plurality of frames comprising a header portion and a payload portion;

wherein each of the signals in the plurality of signals are scrambled according to different scrambling sequences based on seeds selected from one of Table A and Table B;

18. The apparatus of claim 17, wherein each frame in the plurality of frames has a structure according to a Digital Video Broadcast (DVB) standard.

19. The apparatus of claim 17, further comprising transmitting the signals according to a modulation scheme including Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 8 PSK, 16 Amplitude Phase Shift Keying (APSK), 32 APSK, and a high order Quadrature Amplitude Modulation (QAM).

20. The apparatus method of claim 17, wherein each frame further comprises information encoded according to a Low Density Parity Check (LDPC) coding scheme.