Physical layer header scrambling in satellite broadcast systems

• US 20050226418A1
• Filed: 04/11/2005
• Published: 10/13/2005
• 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: Sun, Feng-Wen, Santoru, Joseph, Lee, Lin-Nan, Maitra, Shamik, Chen, Ernest C., Lin, Tung-Sheng, Lai, Dennis, Ancken, Adam Von, Zhou, Guangcai
• Granted Patent: US 7,551,736 B2
• Time in Patent Office: Days
• US Class Current: 380/233
• 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 scrambling a first header of the first signal using a first scrambling code, scrambling a second header of the second signal using a second scrambling code, and transmitting the first signal and the second signal with the scrambled first header and the scrambled second header 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, each signal transmitted on different channels within the communication system, comprising:

scrambling a first header of the first signal using a first scrambling code;

scrambling a second header of the second signal using a second scrambling code; and

transmitting the first signal and the second signal with the scrambled first header and the scrambled second header over different channels of the communication system.

2. The method of claim 1, wherein the first signal further comprises a first pilot block, and the pilot block is also scrambled using the first scrambling code.

3. The method of claim 2, wherein the first signal further comprises a first payload portion and the second signal further comprises a second payload portion, and the first payload portion is scrambled using a third scrambling code and the second payload portion is scrambled using a fourth scrambling code.

4. The method of claim 3, wherein the third scrambling code and the fourth scrambling code are Gold codes.

5. The method of claim 4, wherein the first scrambling code and the third scrambling code are a mated pair.

6. The method of claim 5, wherein the first scrambling code and the second scrambling code are selected from a limited number of codes.

7. The method of claim 6, wherein a number of the limited number of codes is determined based on a number of interfering channels within the communication system.

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

transmitting information associated with the first scrambling code and the second scrambling code to a receiver within the communication system.

10. The apparatus of claim 8, wherein the first signal further comprises a first pilot block, and the pilot block is also scrambled using the first scrambling code.

11. The apparatus of claim 10, wherein the first signal further comprises a first payload portion and the second signal further comprises a second payload portion, and the first payload portion is scrambled using a third scrambling code and the second payload portion is scrambled using a fourth scrambling code.

12. The apparatus of claim 11, wherein the third scrambling code and the fourth scrambling code are Gold codes.

13. The apparatus of claim 12, wherein the first scrambling code and the third scrambling code are a mated pair.

14. The apparatus of claim 13, wherein the first scrambling code and the second scrambling code are selected from a limited number of codes.

15. The apparatus of claim 14, wherein a number of the limited number of codes is determined based on a number of interfering channels within the communication system.

16. The apparatus of claim 8, wherein the transmitter sends information associated with the first scrambling code and the second scrambling code to a receiver within the communication system.

9. An apparatus for minimizing co-channel interference in a communication system having at least a first signal and a second signal, each signal transmitted on different channels within the communication system, comprising:

a scrambler for scrambling at least a portion of a first header of the first signal using a first scrambling code and for scrambling at least a portion of a second header of the second signal using a second scrambling code; and

a transmitter for transmitting the first signal and the second signal over different channels of the communication system.

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

scrambling a first header of the first signal using a first scrambling code;

scrambling a first payload of the first signal using a first Gold code;

scrambling a second header of the second signal using a second scrambling code;

scrambling a second payload of the second signal using a second Gold code; and

transmitting the first signal and the second signal with the scrambled first header and the scrambled second header over different channels of the communication system.

18. The method of claim 17, wherein the first scrambling code and the second scrambling code are selected to minimize co-channel interference between the first signal and the second signal.

19. The method of claim 18, wherein the first scrambling code and the first Gold code are used as a mated pair of codes.

20. The method of claim 19, wherein each signal further comprises at least one pilot block, the pilot blocks scrambled with their respective header.