LINK ADAPTATION IN MULTI-CARRIER COMMUNICATION SYSTEMS

• US 20110286544A1
• Filed: 12/29/2010
• Published: 11/24/2011
• Est. Priority Date: 05/21/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Atheros Communications Incorporated (Qualcomm, Inc.)
• Inventors: Rende, Deniz, Afkhamie, Kaywan, Avudainayagam, Arun, Yonge, Lawrence W. III
• Granted Patent: US 8,781,006 B2
• Time in Patent Office: Days
• US Class Current: 375/295
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 27/2634 Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels

Abstract

A method for transmitting information in a multi-carrier system includes: identifying a first set of carrier signals, associated with a first code rate; and identifying a second set of carrier signals, associated with a second code rate. The method also includes partitioning a first sequence of bits representing a single symbol into a first group of bits associated with the first code rate and at least a second group of bits associated with the second code rate; interleaving a subset of bits from the first group to map multiple bits from the first group to respective carrier signals in the first set of carrier signals to achieve the first code rate; and interleaving a subset of bits from the second group to map multiple bits from the second group to respective carrier signals in the second set of carrier signals to achieve the second code rate.

Claims

1. A method for transmitting information in a multi-carrier system, the method comprising:

identifying a first set of carrier signals, each carrier signal in the first set of carrier signals associated with a first code rate;

identifying a second set of carrier signals, each carrier signal in the second set of carrier signals associated with a second code rate, the second code rate different from the first code rate;

partitioning a first sequence of bits representing a single symbol into a first group of bits associated with the first code rate and at least a second group of bits associated with the second code rate;

interleaving a subset of bits from the first group of bits to map multiple bits from the first group of bits to respective carrier signals in the first set of carrier signals to achieve the first code rate on an average over the first set of carrier signals;

interleaving a subset of bits from the second group of bits to map multiple bits from the second group of bits to respective carrier signals in the second set of carrier signals to achieve the second code rate on an average over the second set of carrier signals;

modulating one or more of the carrier signals in the first set of carrier signals using the mapped bits from the first group; and

modulating one or more of the carrier signals in the second set of carrier signals using the mapped bits from the second group.

2. The method of claim 1, further comprising identifying a third set of carrier signals, each carrier in the third set of carrier signals associated with a third code rate that is different from the first code rate and the second code rate.

3. The method of claim 2, further comprising:

partitioning the first sequence of bits into a third group of bits in addition to the first group of bits and the second group of bits;

interleaving bits from the third group of bits to map multiple bits from the third group of bits to respective carrier signals in the third set of carrier signals to achieve the third code rate on average over the third set of carrier signals; and

modulating multiple carrier signals in the third set of carrier signals using the mapped bits from the third group.

4. The method of claim 1, further comprising:

producing an encoded set of bits by applying an error correction code with a base code rate to information bits, the encoded set of bits comprising (1) the information bits and redundancy bits introduced via the error correction code or (2) the redundancy bits introduced via the error correction code; and

selecting a subset of bits from the encoded set as the first sequence of bits representing the single symbol.

5. The method of claim 4, wherein the first sequence of bits comprises (1) a subset of the information bits and a subset of the redundancy bits, or (2) a subset of the redundancy bits.

6. The method of claim 5, wherein the first group of bits and the second group of bits each comprises (1) one or more bits from the subset of the information bits and one or more bits from the subset of the redundancy bits, or (2) one or more bits from the subset of the redundancy bits.

7. The method of claim 6, further comprising choosing the multiple bits from the first group of bits to be interleaved and mapped to respective carrier signals in the first set of carrier signals in accordance with the first code rate.

8. The method of claim 7, wherein choosing the multiple bits in accordance with the first code rate comprises puncturing the redundancy bits included in the first group of bits using a predetermined puncturing pattern.

9. The method of claim 8, wherein the predetermined puncturing pattern maximizes a distance property for the first code rate.

10. The method of claim 1, wherein, for a given channel between a transmitter and a receiver, the first set of carrier signals performs closer to a Shannon capacity of the given channel at the first code rate than at the second code rate and the second set of carrier signals performs closer to the Shannon capacity of the given channel at the second code rate than at the first code rate.

11. The method of claim 1, further comprising puncturing at least one of the first group of bits and the second group of bits to achieve the first code rate on an average over the first set of carrier signals and the second code rate on average over the second set of carrier signals.

12. The method of claim 1, wherein the first set of carrier signals includes carrier signals assigned to different modulation schemes.

13. The method of claim 1, wherein the carrier signals in the first set and the carrier signals in the second set are not sequential in terms of their respective frequencies.

14. The method of claim 1, wherein identifying the first set and the second set of carrier signals comprises determining a quality metric for each carrier signal in the first and second set over a channel between a transmitter and a receiver.

15. The method of claim 14, wherein the quality metric includes at least one of a signal-to-noise ratio, a bit error rate, and a frame error rate.

16. The method of claim 14, wherein the carrier signals in the first set have an improved quality metric than the carrier signals in the second set and the first code rate is higher than the second code rate.

17. An apparatus for transmitting information in a multi-carrier system, the apparatus comprising:

a partitioning module including circuitry to

identify a first set of carrier signals, each carrier signal in the first set of carrier signals associated with a first code rate,

identify a second set of carrier signals, each carrier signal in the second set of carrier signals associated with a second code rate, the second code rate different from the first code rate,

partition a first sequence of bits representing a single symbol into a first group of bits associated with the first code rate and at least a second group of bits associated with the second code rate;

an interleaver including circuitry to

interleave a subset of bits from the first group of bits to map multiple bits from the first group of bits to respective carrier signals in the first set of carrier signals to achieve the first code rate on an average over the first set of carrier signals, and

interleave a subset of bits from the second group of bits to map multiple bits from the second group of bits to respective carrier signals in the second set of carrier signals to achieve the second code rate on an average over the second set of carrier signals; and

a modulator including circuitry to

modulate multiple carrier signals in the first set of carrier signals using the mapped bits from the first group, and

modulate multiple carrier signals in the second set of carrier signals using the mapped bits from the second group.

18. The apparatus of claim 17, wherein the interleaver comprises a bank of interleavers, each interleaver configured to operate on bits in a given group from the first sequence of bits.

19. The apparatus of claim 17, wherein the interleaver is configured to operate on bits across groups from the first sequence of bits.

20. The apparatus of claim 17, wherein the interleaver is configured to operate on bits from the first sequence of bits prior to being partitioned into groups.