System and method for Huffman shaping in a data communication system

• US 7,460,595 B2
• Filed: 07/25/2005
• Issued: 12/02/2008
• Est. Priority Date: 08/11/2000
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Carlson, Arthur J., Ungerboeck, Gottfried
• Primary Examiner(s): Ha; Dac V
• Application Number:
  US11/188,301
• Publication Number:
  US 20050271139A1
• Time in Patent Office: 1,226 Days
• Field of Search: 375261-265, 375/240, 375/254, 375/296, 375/298, 704/500, 704/501, 704/503, 704/504, 341/65, 341/200, 348/384
• US Class Current: 375/240
• CPC Class Codes: H03M 7/40 Conversion to or from variable length codes, e.g. Shannon-Fano code, Huffman code, Morse code
• CPC Class Codes: H04L 27/3405 Modifications of the signal space to increase the efficiency of transmission, e.g. reduction of the bit error rate, bandwidth, or average power

Abstract

In a communication system, Huffman coding techniques are used to obtain shaping gains for an improvement in data transmission rates. More particularly, a novel method of Huffman shaping is described that achieves a shaping gain of greater than 1 dB. The shaping gain results in a higher data rate transmission in a communication system where transmitted power is constrained.

Claims

1. A method of transmitting data, comprising:

inputting data into a transmitter;

scrambling the inputted data;

accumulating the scrambled data, the accumulated data forming Huffman codewords;

mapping the formed Huffman codewords into modulation symbols; and

transmitting, at a constant rate, the modulation symbols from the transmitter.

2. The method according to claim 1, wherein the scrambled data comprises pseudo-random data.

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

performing channel coding operations to achieve coding gain in addition to any gains attributable to the Huffman codewords.

4. The method according to claim 1, wherein the accumulated data is parsed into Huffman codewords.

5. The method according to claim 1, comprising:

framing the modulation symbols.

6. The method according to claim 5,

wherein framing the modulation symbols comprises establishing symbol frames,

wherein the symbol frames have a same symbol frame length and comprise a same number of modulation symbols.

7. The method according to claim 6, wherein the symbol frames comprise a synchronization and pointer field that comprises a synchronization subfield and a pointer subfield.

8. The method according to claim 7, wherein the symbol frame comprises a portion of a first data frame and a portion of a second data frame.

9. The method according to claim 8, wherein the pointer subfield provides an offset value indicating a location of the second portion of the second data frame.

10. The method according to claim 8, wherein the symbol frame does not comprises a portion of a third data frame.

11. The method according to claim 6, wherein the modulation symbols comprise variable-length modulation symbols.

12. The method according to claim 1, wherein the modulation symbols comprise variable-length modulation symbols.

13. The method according to claim 1, wherein transmitting the modulation symbols comprises transmitting the modulation symbols onto a communications channel.

14. The method according to claim 1, wherein the method does not comprises trellis shaping or shell mapping.

15. The method according claim 1, wherein the modulation symbols are PAM symbols.

16. The method according to claim 1, wherein the modulation symbols are QAM symbols.

17. The method according to claim 1, wherein the modulation symbols do not form a uniform distribution.

18. The method according to claim 1, wherein the modulation symbols are not equiprobable.

19. The method according to claim 1, wherein the modulation symbols are equally spaced.

20. The method according to claim 1, wherein the method provides Huffman shaping gains.

21. The method according to claim 1, wherein the modulation symbols form a symbol constellation with unequal symbol probabilities and provide a shaping gain of greater than 1 dB.

22. The method according to claim 21, wherein the modulation symbols provide a shaping gain of approximately 1.35 dB.

23. The method according to claim 21, wherein the modulation symbols provide a shaping gain of approximately 1.5 dB.

24. The method according to claim 1, wherein the method provides variable-rate encoded voice or video streams over one or more constant rate channels.

25. The method according to claim 1, wherein the transmitter comprises a source encoder and a channel encoder, the source encoder being operatively coupled to the channel encoder.

26. The method according to claim 25, wherein the channel encoder comprises a shaper and a modulator, the shaper being operatively coupled to the modulator.

27. The method according to claim 26, wherein the shaper comprises a Huffman decoder and a mapper, the Huffman decoder being operatively coupled to the mapper.