Synchronization apparatus and method for a return link power control for satellite systems

• US 6,771,615 B1
• Filed: 08/18/2000
• Issued: 08/03/2004
• Est. Priority Date: 08/18/2000
• Status: Expired due to Term

• Current Assignee: Hughes Network Systems LLC (Echostar Corporation)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Park, Yunsang, Parr, Michael
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US09/642,283
• Time in Patent Office: 1,446 Days
• Field of Search: 370/321, 370/324, 370/350, 370/470, 370/471, 370/474, 370/503, 370/509, 370/514, 370/535, 370/316, 370/318, 375/240, 375/240.01, 375/240.24, 375/240.26, 375/240.28, 375/362, 375/365, 375/368, 455/12.1, 455/13.2, 455/13.4, 714/752, 714/775, 714/776, 714/781, 714/783, 714/789
• US Class Current: 370/318
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27

Abstract

An approach for providing message synchronization in a communication system is disclosed. Using a selected channel coding method (e.g., Golay coding), an encoder encodes a message for transmission over a communication channel. An interleaver applies a predetermined interleaving pattern to the encoded message. A mask pattern with a prescribed sequence of bits is applied to the interleaved message; the prescribed sequence is ordered to eliminate an all zeros bit pattern and an all ones bit pattern. A multiplexer multiplexes the masked message with data traffic over the communication channel. The masked message is segmented into multiple blocks of a fixed length. At the receiver side, the mask pattern is applied to the demultiplexed message. The message is de-interleaved and decoded to restore the original message. Such an approach synchronizes the message blocks without adding overhead bits for synchronization and has particular applicability to the synchronization of power control messages in a satellite communication system.

Claims

1. A method of performing message synchronization, the method comprising:

encoding a message for transmission over a communication channel;

interleaving the encoded message according to a predetermined interleaving pattern;

applying a mask pattern having a prescribed sequence of bits to the interleaved message, the prescribed sequence being ordered to eliminate an all zero bit pattern and an all ones bit pattern;

segmenting the masked message into a plurality of blocks, each of the blocks having a fixed length; and

multiplexing each of the blocks with data traffic for transmission over the communication channel.

2. The method according to claim 1, further comprising:

receiving the multiplexed traffic from the communication channel;

demultiplexing the received multiplexed traffic to output a received encoded message;

applying the mask pattern to the received encoded message;

de-interleaving the received encoded message based upon the interleaving pattern; and

decoding the de-interleaved message.

3. The method according to claim 2, further comprising:

generating the interleaving pattern and the mask pattern.

4. The method according to claim 2, wherein the generating step comprises:

(a) selecting a test interleaving pattern;

(b) selecting a test mask pattern;

(c) generating a random message having a random arrangement of bits;

(d) encoding the random message;

(e) applying the test interleaving pattern and the test mask pattern to the random message to output a test message;

(f) determining whether the test message is synchronized according to a predetermined threshold of number of synchronization errors;

(g) selecting another test interleaving pattern and another mask pattern based upon determining that the test message is not synchronized; and

(h) repeating steps (a)-(g) until a final interleaving pattern and a final mask pattern is determined, wherein the final interleaving pattern yields synchronization errors in accordance with the predetermined threshold.

5. The method according to claim 4, wherein the steps (a)-(h) are performed on a block by block basis.

6. The method according to claim 1, wherein the encoding step utilizes Golay codes.

7. The method according to claim 1, wherein the encoding step utilizes non-synchronized block codes.

8. The method according to claim 1, wherein the message in the encoding step has a length of 12 bits, the encoded message in the interleaving step has a length of 24 bits, and the fixed length of each of the blocks in the segmenting step is 4 bits.

9. The method according to claim 8, wherein the interleaving pattern in the interleaving step is {60181213191720148215213942210165111723}.

10. The method according to claim 9, wherein the mask pattern in the applying step is {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0}.

11. A communication system for providing message synchronization, comprising:

an encoder configured to encode a message for transmission over a communication channel;

an interleaver coupled to the encoder and configured to interleave the encoded message according to a predetermined interleaving pattern;

an adder configured to add a mask pattern having a prescribed sequence of bits to the interleaved message, the prescribed sequence being ordered to eliminate an all zero bit pattern and an all ones bit pattern; and

a multiplexer configured to multiplex the masked message with data traffic for transmission over the communication channel, the masked message being segmented into a plurality of blocks, each of the blocks having a fixed length.

12. The system according to claim 11, further comprising:

a demultiplexer configured to demultiplex the multiplexed traffic to output a received message;

another adder coupled to the demultiplexer and configured to apply the mask pattern to the received encoded message;

a de-interleaver coupled to the other adder and configured to de-interleave the received message based upon the interleaving pattern; and

a decoder configured to recover an unencoded message.

13. The system according to claim 12, further comprising:

a processor configured to generate the interleaving pattern and the mask pattern, the processor configured to perform the steps of,

(a) selecting a test interleaving pattern,

(b) selecting a test mask pattern,

(c) generating a random message having a random arrangement of bits;

(d) encoding the random message,

(e) applying the test interleaving pattern and the test mask pattern to the random message to output a test message,

(f) determining whether the test message is synchronized according to a predetermined threshold of number of synchronization errors,

(g) selecting another test interleaving pattern and another mask pattern based upon determining that the test message is not synchronized, and

(h) repeating steps (a)-(g) until a final interleaving pattern and a final mask pattern is determined, wherein the final interleaving pattern yields synchronization errors in accordance with the predetermined threshold; and

a memory configured to store the interleaving pattern and the mask pattern.

14. The system according to claim 13, wherein the steps (a)-(h) are performed by the processor on a block by block basis.

15. The system according to claim 11, wherein the encoder utilizes Golay codes.

16. The system according to claim 11, wherein the encoder utilizes non-synchronized block codes.

17. The system according to claim 11, wherein the message has a length of 12 bits, the encoded message has a length of 24 bits, and the fixed length of each of the blocks is 4 bits.

18. The system according to claim 17, wherein the interleaving pattern is {7 0 19 12 13 20 1 8 22 15 8 2 16 23 3 9 4 24 10 17 6 11 18 25}.

19. The system according to claim 18, wherein the mask pattern is {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0}.

20. A computer readable medium containing program instructions for execution on a computer system, which when executed by a computer, cause the computer system to perform method steps for providing message synchronization, the method comprising the steps of:

encoding a message for transmission over a communication channel;

interleaving the encoded message according to a predetermined interleaving pattern;

applying a mask pattern having a prescribed sequence of bits to the interleaved message, the prescribed sequence being ordered to eliminate an all zero bit pattern and an all ones bit pattern;

segmenting the masked message into a plurality of blocks, each of the blocks having a fixed length; and

multiplexing each of the blocks with data traffic for transmission over the communication channel.

21. The computer readable medium according to claim 20, wherein the computer readable medium further includes computer-executable instructions for causing the computer system to perform the steps of:

receiving the multiplexed traffic from the communication channel;

demultiplexing the received multiplexed traffic to output a received encoded message;

applying the mask pattern to the received encoded message;

de-interleaving the received encoded message based upon the interleaving pattern; and

decoding the de-interleaved message.

22. The computer readable medium according to claim 21, wherein the computer readable medium further includes computer-executable instructions for causing the computer system to perform the step of:

generating the interleaving pattern and the mask pattern.

23. The computer readable medium according to claim 21, wherein the generating step comprises:

(a) selecting a test interleaving pattern;

(b) selecting a test mask pattern;

(c) generating a random message having a random arrangement of bits;

(d) encoding the random message;

(e) applying the test interleaving pattern and the test mask pattern to the random message to output a test message;

(f) determining whether the test message is synchronized according to a predetermined threshold of number of synchronization errors;

(g) selecting another test interleaving pattern and another mask pattern based upon determining that the test message is not synchronized; and

(h) repeating steps (a)-(g) until a final interleaving pattern and a final mask pattern is determined, wherein the final interleaving pattern yields synchronization errors in accordance with the predetermined threshold.

24. The computer readable medium according to claim 23, wherein the steps (a)-(h) are performed on a block by block basis.

25. The computer readable medium according to claim 20, wherein the encoding step utilizes Golay codes.

26. The computer readable medium according to claim 20, wherein the encoding step utilizes non-synchronized block codes.

27. The computer readable medium according to claim 20, wherein the message in the encoding step has a length of 12 bits, the encoded message in the interleaving step has a length of 24 bits, and the fixed length of each of the blocks in the segmenting step is 4 bits.

28. The computer readable medium according to claim 27, wherein the interleaving pattern in the interleaving step is {6 0 18 12 13 19 1 7 20 14 8 2 15 21 3 9 4 22 10 16 5 11 17 23}.

29. The computer readable medium according to claim 28, wherein the mask pattern in the applying step is {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0}.