System and method for huffman shaping in a data communication system

• US 20050271139A1
• Filed: 07/25/2005
• Published: 12/08/2005
• Est. Priority Date: 08/11/2000
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Arthur J. Carlson, Gottfried Ungerboeck
• Inventors: Carlson, Arthur J., Ungerboeck, Gottfried
• Granted Patent: US 7,460,595 B2
• Time in Patent Office: Days
• 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. In a communication system, a method of communicating data comprising:

accepting data from a source of user data;

accumulating the data until a Huffman codeword is recognized;

mapping the Huffman codeword into a channel symbol; and

applying the channel symbol to an input of a channel.

2. The method of claim 1 further comprising scrambling the user data into pseudo-random data.

3. The method of claim 1 further comprising performing additional channel coding operations to achieve coding gain in addition to shaping gain.

4. The method of claim 1 further comprising performing a framing operation on the data.

5. The method of claim 1 further comprising modulating channel symbols in various ways.

6. The method of claim 1 further comprising receiving symbols from an output of the channel.

7. The method of claim 2 further comprising:

receiving symbols from an output of the channel; and

descrambling the received pseudo-random data into user data.

8. The method of claim 3 further comprising receiving symbols from an output of the channel by performing additional channel decoding operations.

9. The method of claim 4 further comprising:

receiving symbols from an output of the channel; and

performing a deframing operation.

10. The method of claim 5 further comprising receiving symbols from an output of the channel by performing demodulation operations.

11. The method of claim 6 further comprising performing a Huffman encoding operation on received channel symbols.

12. The method of claim 11 further comprising communicating the received data to a sink of user data.

13. The method of claim 1 wherein a symbol constellation with unequal symbol probabilities leads to a shaping gain of greater than 1 dB.

14. The method of claim 13 whereby a shaping gain of approximately 1.35 dB is attained.

15. The method of claim 13 whereby a shaping gain of approximately 1.5 dB is attained.

16. A communication system comprising:

a communication node having a shaper, the shaper generating channel symbols in a constellation that exhibits a shaping gain of greater than 1 dB.

17. The system of claim 16 whereby a shaping gain of approximately 1.35 dB is attained.

18. The system of claim 16 whereby a shaping gain of approximately 1.5 dB is attained.

19. The system of claim 16 wherein the communication node further comprises a transmitter, and wherein the transmitter comprises the shaper.

20. A communication system comprising a communication node that performs a Huffman decoding operation to generate channel symbols.

21. The system of claim 20 wherein the Huffman decoding operation results in a constellation of symbols and associated symbol propabilities leading to a shaping gain greater than 1 dB.

22. The system of claim 21 whereby a shaping gain of approximately 1.35 dB is attained.

23. The system of claim 21 whereby a shaping gain of approximately 1.5 dB is attained.

24. The system of claim 20 wherein the communication node has a transmitter, and wherein the Huffman decoding operation is performed by the transmitter.