Coding and decoding packetized data

• US 20060268997A1
• Filed: 05/24/2005
• Published: 11/30/2006
• Est. Priority Date: 05/24/2005
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Thaler, Patricia A.
• Granted Patent: US 7,440,513 B2
• Time in Patent Office: Days
• US Class Current: 375/242
• CPC Class Codes: H03M 5/145 Conversion to or from block codes or representations thereof
• CPC Class Codes: H04J 2203/0089 Multiplexing, e.g. coding, scrambling, SONET
• CPC Class Codes: H04J 3/1617 carrying packets or ATM cells
• CPC Class Codes: H04L 25/03866 using scrambling

Abstract

A method for coding a packet of information words into frames for transmission, includes receiving blocks of input data, including control words and the packet of information words. When the block consists exclusively of information words, a master transition having a first sense is scrambled and appended to the block to form one of the frames. When the block does not consist exclusively of information words: the block is condensed to accommodate a TYPE word; a TYPE word having a value that indicates a structural property of the block is generated and inserted into the block; and a master transition having a second sense, opposite to the first sense, is scrambled and appended to the block to form one of the frames.

Claims

1. A method for coding a packet of information words into frames for transmission, the method comprising:

receiving blocks of input data, the input data including control words and the packet of information words, the packet having a start preceded by ones of the control words and an ending followed by others of the control words, the blocks being smaller than the packet;

determining when a block consists exclusively of information words;

when the block consists exclusively of information words, scrambling a master transition having a first sense and appending the scrambled master transition to the block to form one of the frames;

when the block does not consist exclusively of information words;

condensing the block to accommodate a TYPE word;

generating the TYPE word having a value that indicates a structural property of the block, and inserting the TYPE word into the block; and

scrambling a master transition having a second sense, opposite to the first sense, and appending the scrambled master transition to the block to form one of the frames.

2. The method of claim 1, wherein the generated TYPE word has a value that indicates one of the following structural properties of the block:

(a) a position of the start of the packet in the block, (b) a position of the end of the packet in the block, and (c) the block being composed exclusively of control words.

3. The method of claim 1, and further comprising:

recoverably scrambling the block prior to transmission of the block.

4. The method of claim 1, wherein the master transition is a 2-bit value of either 01 or 10.

5. The method of claim 4, wherein both bits of the master transition are scrambled based on a single scrambler bit, and wherein the scrambled master transition is a 2-bit value of either 01 or 10.

6. A coder for coding blocks of input data into respective frames for transmission, the input data including control words and a packet of information words, the packet having a start preceded by ones of the control words and an ending followed by others of the control words, the blocks being smaller than the packet, the coder comprising:

a type word generator that receives a block and generates a TYPE word for the block, the TYPE word having a value that indicates a structural property of the block;

a master transition generator that operates in response to the TYPE word and generates a master transition in a first sense when the TYPE word indicates that the block is composed exclusively of information words, and otherwise generates the master transition in a second sense, opposite to the first sense;

a first scrambler that scrambles the master transition, thereby forming a scrambled master transition;

a payload field generator that operates in response to the TYPE word and that adopts the block to form a payload field of a frame corresponding to the block when the TYPE word indicates that the block is composed exclusively of information words, and that otherwise condenses the block and inserts the TYPE word into the block to form the payload field; and

a frame assembler that appends the scrambled master transition to the payload field to form the frame.

7. The coder of claim 6, wherein the generated TYPE word has a value that indicates one of the following structural properties of the block:

(a) whether the block is composed exclusively of information words, (b) a position of the start of the packet in the block, (c) a position of the end of the packet in the block, and (d) whether the block is composed exclusively of control words.

8. The coder of claim 6, wherein the first scrambler is also configured to scramble the payload field.

9. The coder of claim 6, and further comprising a second scrambler interposed between the payload field generator and the frame assembler for scrambling the payload field.

10. The coder of claim 9, wherein the first scrambler is a 16-bit scrambler.

11. The coder of claim 9, wherein the first scrambler is an 8-bit scrambler.

12. The coder of claim 6, wherein the master transition is a 2-bit value of either 01 or 10, wherein both bits of the master transition are scrambled based on a single scrambler bit, and wherein the scrambled master transition is a 2-bit value of either 01 or 10.

13. The coder of claim 12, wherein the scrambler bit is provided by a second scrambler that scrambles the payload field.

14. A method of decoding a frame of data, the frame being one of a set of frames that represents a packet of information words and that additionally represents coded control words preceding and following the packet, the frames each including a scrambled master transition and a payload field, the payload field being one of (a) composed exclusively of ones of the information words, and (b) including a TYPE word that identifies a structure of the payload field, the method comprising:

descrambling the scrambled master transition, the descrambled master transition being in a first state when the payload field is composed exclusively of ones of the information words, and otherwise being in a second state;

when the descrambled master transition is in the first state, adopting the payload field as a block of received data; and

when the descrambled master transition is not in the first state;

extracting the TYPE word from the payload field;

expanding the payload field in response to the TYPE word; and

adopting the payload field after expansion as a block of received data.

15. The method of claim 14, wherein:

the payload field is scrambled; and

the method additionally comprises descrambling the payload field.

16. The method of claim 14, wherein the scrambled master transition is a 2-bit value of either 01 or 10.

17. The method of claim 16, wherein both bits of the scrambled master transition are descrambled based on a single descrambler bit, and wherein the descrambled master transition is a 2-bit value of either 01 or 10.

18. A decoder for decoding a frame of data, the frame being one of a set of frames that represents a packet of information words and that additionally represents coded control words preceding and following the packet, the frames each including a scrambled master transition and a payload field, the payload field being one of (a) composed exclusively of ones of the information words, and (b) including a TYPE word that identifies a structure of the payload field, the decoder comprising:

a frame decoder that receives the frame and separates the frame into the scrambled master transition and the payload field;

a first descrambler that descrambles the scrambled master transition, the descrambled master transition being in a first state when the payload field is composed exclusively of ones of the information words, and otherwise being in a second state;

a type word extractor connected to receive the payload field and the descrambled master transition and operating to extract the TYPE word from the payload field when the descrambled master transition is in the second state; and

a block generator connected to receive the payload field, the TYPE word and the descrambled master transition, the block generator operating;

when the descrambled master transition is in the first state, to adopt the payload field as a block of received data; and

when the descrambled master transition is in the second state, to expand the payload field in response to the TYPE word and to adopt the payload field after expansion as the block of received data.

19. The decoder of claim 18, wherein:

the payload field is scrambled; and

the decoder additionally comprises a second descrambler connected to receive the payload field from the frame decoder.

20. The decoder of claim 19, wherein the first descrambler descrambles the scrambled master transition based on a single descrambler bit provided by the second descrambler.