SHIFTED CHANNEL CHARACTERISTICS FOR MITIGATING CO-CHANNEL INTERFERENCE

• US 20090052503A1
• Filed: 04/14/2008
• Published: 02/26/2009
• 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
• Granted Patent: US 8,594,575 B2
• Time in Patent Office: Days
• US Class Current: 375/148
• 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 device 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:

a transmitter for transmitting the first signal and the second signal simultaneously from the antenna, the transmitter comprising;

an encoder;

a scrambler, coupled to the encoder, and

a modulator, coupled to the scrambler, wherein the scrambler shifts a characteristic of the first signal with respect to a like characteristic of the second signal to mitigate co-channel interference.

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

3. The device of claim 1, wherein the characteristic is a transmission code schema.

4. The device 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.

5. The device of claim 1, wherein the characteristic is a frequency of transmission of the first signal.

6. The device of claim 1, wherein the transmitter transmits information associated with the shifted characteristic to a receiver within the communication system.

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

8. The device of claim 7, wherein the content is selected from a preselected set of contents for the SOF.

9. The device of claim 1, wherein the encoder is a Low Density Parity Check (LDPC) encoder.

10. The device of claim 9, wherein the encoder is also a Bose-Chaudhuri-Hocquenghem (BCH) encoder.

11. A device 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:

a transmitter for transmitting the first signal and the second signal simultaneously from the antenna, the transmitter comprising;

an encoder; and

a scrambler, coupled to the encoder, wherein the scrambler shifts at least one characteristic of the first signal with respect to a corresponding characteristic of the second signal to mitigate co-channel interference between the first signal and the second signal.

12. The device of claim 11, wherein the characteristic is a transmission code schema.

13. The device of claim 12, wherein the characteristic further includes a start time of a Start-Of-Frame (SOF) of the first signal.

14. The device of claim 13, wherein the start time is shifted at least a portion of a bit.

15. The device of claim 14, wherein the characteristic further includes an in-phase (I) portion of the first signal and a quaternary phase (Q) portion of the first signal.

16. The device of claim 15, 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.

17. The device of claim 16, wherein the characteristic is a frequency of transmission of the first signal.

18. The device of claim 17, wherein the transmitter transmits information associated with the shifted characteristic to a receiver within the communication system.

19. A device 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:

a transmitter for transmitting the first signal and the second signal simultaneously from the antenna, the transmitter comprising at least a scrambler, wherein the scrambler shifts at least one characteristic of the first signal with respect to a corresponding characteristic of the second signal to mitigate co-channel interference between the first signal and the second signal.

20. The device of claim 19, wherein the characteristic is a start time of a Start-Of-Frame (SOF) of the first signal.