Shifted channel characteristics for mitigating co-channel interference

• US 7,412,209 B2
• Filed: 04/11/2005
• Issued: 08/12/2008
• Est. Priority Date: 04/12/2004
• Status: Active Grant

• Current Assignee: DTVG Licensing, Inc. (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Santoru, Joseph, Maitra, Shamik, Chen, Ernest C., Lin, Tung-Sheng, Lai, Dennis, Zhou, Guangcai
• Primary Examiner(s): Moazzami; Nasser
• Assistant Examiner(s): Baum; Ronald
• Application Number:
  US11/102,983
• Publication Number:
  US 20050229230A1
• Time in Patent Office: 1,219 Days
• Field of Search: None
• US Class Current: 455/63.1
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• 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: H04N 21/2347 involving video stream encryption
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 21/6143 involving transmission via a satellite
• CPC Class Codes: H04N 5/211 Ghost signal cancellation H04N23/81 takes precedence
• CPC Class Codes: H04N 7/16 Analogue secrecy systems; Analogue subscription systems
• CPC Class Codes: H04N 7/163 by receiver means only
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests

Abstract

Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises shifting a characteristic of the first signal with respect to a like characteristic of the second signal to mitigate co-channel interference, and transmitting the first signal and the second signal over different channels of the communication system.

Claims

1. A method for minimizing co-channel interference in a communication system having at least a first signal and a second signal transmitted at the same frequency from an antenna, each signal transmitted on different channels within the communication system, comprising:

shifting a characteristic of the first signal with respect to a like characteristic of the second signal to mitigate co-channel interference; and

transmitting the first signal and the second signal simultaneously from the antenna over different channels of the communication system.

2. The method of claim 1, wherein the characteristic is a start time of a Start-Of-Frame (SOF) of the first signal.

3. The method of claim 2, wherein the start time is shifted at least a portion of a bit in the SOF.

4. The method of claim 1, wherein the characteristic is a transmission code schema.

5. The method of claim 4, wherein the transmission code schema is selected from a group consisting of QPSK, 8PSK, and 16ASK.

6. The method of claim 1, wherein the characteristic is an in-phase (I) portion of the first signal and a quaternary phase (Q) portion of the first signal.

7. The method of claim 6, wherein the I and Q portions of the first signal are inverted with respect to an I portion and a Q portion of the second signal.

8. The method of claim 1, wherein the characteristic is a frequency of transmission of the first signal.

9. The method of claim 1, further comprising the step of:

transmitting information associated with the shifted characteristic to a receiver within the communication system.

10. The method of claim 1, wherein the characteristic is a content of the Start-Of-Frame (SOF) of the first signal.

11. The method of claim 10, wherein the content is selected from a preselected set of contents for the SOF.

12. A method for minimizing co-channel interference in a satellite-based communication system having at least a first signal and a second signal transmitted at the same frequency from an antenna, each signal comprising at least a header and a payload, each signal being transmitted on different channels within the communication system, comprising:

shifting at least one characteristic of the first signal with respect to a corresponding characteristic of the second signal to mitigate co-channel interference between thc first signal and the second signal; and

transmitting the first signal and the second signal simultaneously from the antenna over different channels of the communication system.

13. The method of claim 12, wherein the characteristic is a transmission code schema.

14. The method of claim 13, wherein the transmission code schema is selected froma group consisting of QPSK, 8PSK, and 16ASK.

15. The method of claim 14, wherein the characteristic further includes a start time of a Start-Of-Frame (SOF) of the first signal.

16. The method of claim 15, wherein the start time is shifted at least a portion of a bit.

17. The method of claim 16, wherein the characteristic further includes an in-phase (I) portion of the first signal and a quaternary phase (Q) portion of the first signal.

18. The method of claim 17, wherein the I and Q portions of the first signal are inverted with respect to an I portion and a Q portion of the second signal.

19. The method of claim 18, wherein the characteristic is a frequency of transmission of the first signal.

20. The method of claim 19, further comprising the step of:

transmitting information associated with the shifted characteristic to a receiver within the communication system.