System and method for Huffman shaping in a data communication system

• US 7,106,794 B2
• Filed: 07/03/2001
• Issued: 09/12/2006
• Est. Priority Date: 08/11/2000
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Carlson, Arthur J., Ungerboeck, Gottfried
• Primary Examiner(s): Ha, Dac V.
• Application Number:
  US09/898,850
• Publication Number:
  US 20020044073A1
• Time in Patent Office: 1,897 Days
• Field of Search: 375261-365, 375/285, 375/296, 375/240, 375/298, 375/254, 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. In a communication system, a method of communicating data comprising:

acccpting data from a source of user data;

accumulating the data until a Huffman codeword is recognized;

mapping the Huffman codeword into a channel symbol, the mapping generating a distribution that is aproximately characterized by a sampled Gaussian distribution; and

applying the channel symbol to an input of a channel at a constant rate.

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

3. 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.

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

5. The method of claim 4 further comprising receiving symbols from an output of the channel by performing additional channel decoding operations.

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

7. The method of claim 6 further comprising:

receiving symbols from an output of the channel; and

performing a deframing operation.

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

9. The method of claim 8 further comprising receiving symbols from an output of the channel by performing demodulation operations.

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

11. The method of claim 10 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,

wherein the shaper comprising a Huffman decoder that maps channel symbols into a distribution that is approximately a sampled Gaussian distribution, and

wherein the communication node transmits channel symbols at a constant rate.

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 that are characterized approximately by a sampled Gaussian distribution, the communication node transmitting the channel symbols at a constant rate.

21. The system of claim 20 wherein the Huffman decoding operation results in a constellation of symbols and associated symbol probabilities 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.