Digital audio broadcasting method using puncturable convolutional code

• US 6,108,810 A
• Filed: 03/27/1998
• Issued: 08/22/2000
• Est. Priority Date: 03/27/1998
• Status: Expired due to Term

• Current Assignee: iBiquity Digital Corporation (Adeia Inc.)
• Original Assignee: USA Digital Radio, Inc. (Adeia Inc.)
• Inventors: Cammarata, Denise Maureen, Stehlik, Roy Ronald, Kroeger, Brian William
• Primary Examiner(s): De Cady, Albert
• Assistant Examiner(s): LAMARRE, GUY J
• Application Number:
  US09/049,140
• Time in Patent Office: 879 Days
• Field of Search: 714/790, 714/793, 714/825, 714/97, 714/FOR 104, 375/260
• US Class Current: 714/790
• CPC Class Codes: H03M 13/235 Encoding of convolutional codes, e.g. methods or arrangements for parallel or block-wise encoding
• CPC Class Codes: H03M 13/25 Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM] modulation codes H03M13/31
• CPC Class Codes: H03M 13/35 Unequal or adaptive error protection, e.g. by providing a different level of protection according to significance of source information or by adapting the coding according to the change of transmission channel characteristics
• CPC Class Codes: H03M 13/6375 Rate compatible punctured convolutional [RCPC] codes
• CPC Class Codes: H04H 20/30 by a single channel
• CPC Class Codes: H04H 2201/20 digital audio broadcasting [DAB]
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 2001/0098 Unequal error protection
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/0058 Allocation criteria

Abstract

A broadcasting method encodes program material using convolutional codes having non-puncturable bits and puncturable bits and modulates orthogonal frequency division multiplexed carrier signals with the convolutional codes. The non-puncturable bits are carried by a first group of the carriers and the puncturable bits are carried by a second group of the carriers, where the first group of carrier signals is less susceptible to interference than the second group of carrier signals. The carrier signals are then broadcast to receivers which determine if the carriers in the second group have been corrupted and erase puncturable bits carried by any of the carriers which have been determined to be corrupted. This produces punctured codes which are subsequently decoded to recover the program material.

Claims

1. A broadcasting method comprising the steps of:

encoding program material using convolutional codes having nonpuncturable bits and puncturable bits;

modulating a plurality of orthogonal frequency division multiplexed carrier signals with said convolutional codes, whereby said non-puncturable bits are carried by a first group of said carrier signals and said puncturable bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals; and

broadcasting said carrier signals.

2. The method of claim 1, further comprising the steps of:

receiving said carrier signals;

determining if carrier signals in said second group have been corrupted;

erasing puncturable bits carried by any of said carrier signals which have been determined to be corrupted to produce punctured codes; and

decoding said punctured codes.

3. The method of claim 2, where the step of determining if carrier signals in said second group have been corrupted comprises the step of:

estimating the non-uniform interference to which the carrier signals in said second group of carrier signals have been subjected.

4. The method of claim 1, where different portions of said program material are encoded in said puncturable bits and said non-puncturable bits.

5. The method of claim 4, where one of said non-puncturable bits is a mode control bit.

6. The method of claim 4, wherein said puncturable bits contain audio information and said non-puncturable bits contain data.

7. The method of claim 1, wherein said convolutional codes are rate compatible convolutional codes.

8. The method of claim 1, wherein said puncturable bits are weighted in accordance with a signal-to-noise ratio for each carrier signal in said second group of carrier signals.

9. The method of claim 1, wherein said convolutional codes are systematic codes.

10. The method of claim 1, further comprising the step of:

interleaving said convolutional codes among said carrier signals.

11. The method of claim 10, wherein the step of interleaving said convolutional codes among said carrier signals comprises the step of:

partitioning said convolutional codes.

12. The method of claim 11, further comprising the step of:

mapping partitioned convolutional codes onto said carrier signals.

13. A radio frequency transmitter comprising:

means for encoding program material using convolutional codes having non-puncturable bits and puncturable bits;

means for modulating a plurality of orthogonal frequency division multiplexed carrier signals with said convolutional codes, whereby said non-puncturable bits are carried by a first group of said carrier signals and said puncturable bits are carried by a second group of carrier signals, said first group of carrier signals being less susceptible to interference than said second group of carrier signals; and

means for broadcasting said carrier signals.

14. A radio frequency receiver comprising:

means for receiving a plurality of orthogonal frequency division multiplexed carrier signals with convolutional codes containing puncturable and non-puncturable bits, wherein said non-puncturable bits are carried by a first group of said carrier signals and said puncturable bits are carried by a second group of said carrier signals, said first group of said carrier signals being less susceptible to interference than said second group of said carrier signals;

means for determining if carrier signals in said second group of said carrier signals have been corrupted;

means for erasing puncturable bits carried by any of said carrier signals which have been determined to be corrupted to produce punctured codes; and

means for decoding said punctured codes.

15. A radio frequency receiver comprising:

means for receiving a plurality of orthogonal frequency division multiplexed carrier signals with convolutional codes containing puncturable and non-puncturable bits, wherein said non-puncturable bits are carried by a first group of said carrier signals and said puncturable bits are carried by a second group of said carrier signals, said first group of said carrier signals being less susceptible to interference than said second group of said carrier signals;

means for determining if carrier signals in said second group have been corrupted;

means for weighting puncturable bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted convolutional codes; and

means for decoding said weighted convolutional codes.

16. A method of receiving a radio frequency signal comprising the steps of:

receiving a plurality of orthogonal frequency division multiplexed carrier signals with convolutional codes containing puncturable and non-puncturable bits, wherein said non-puncturable bits are carried by a first group of said carrier signals and said puncturable bits are carried by a second group of said carrier signals, said first group of said carrier signals being less susceptible to interference than said second group of said carrier signals;

determining if carrier signals in said second group of said carrier signals have been corrupted;

erasing puncturable bits carried by any of said carrier signals which have been determined to be corrupted to produce punctured codes; and

decoding said punctured codes.

17. A method for receiving a radio frequency signal comprising the steps of:

receiving a plurality of orthogonal frequency division multiplexed carrier signals with convolutional codes containing puncturable and non-puncturable bits, wherein said non-puncturable bits are carried by a first group of said carrier signals and said puncturable bits are carried by a second group of said carrier signals, said first group of said carrier signals being less susceptible to interference than said second group of said carrier signals;

determining if carrier signals in said second group have been corrupted;

weighting puncturable bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted convolutional codes; and

decoding said weighted convolutional codes.

18. The method of claim 17, wherein said step of determining if carrier signals in said second group have been corrupted comprises the step of:

determining a signal to noise ratio for said carrier signals containing puncturable bits; and

wherein the step of weighting puncturable bits carried by any of said carrier signals which have been determined to be corrupted to produce weighted convolutional codes comprises the steps of;

weighting said puncturable bits in response to said signal to noise ratio.