APPARATUS AND METHOD FOR MULTILEVEL CODING (MLC) WITH BINARY ALPHABET POLAR CODES

• US 20150091742A1
• Filed: 10/01/2014
• Published: 04/02/2015
• Est. Priority Date: 10/01/2013
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Roh, June Chul, Mansour, Mohamed F., Hosur, Srinath, Ionita, Corina Ioana
• Granted Patent: US 10,135,460 B2
• Time in Patent Office: Days
• US Class Current: 341/57
• CPC Class Codes: H03M 13/13 Linear codes
• CPC Class Codes: H03M 13/152 Bose-Chaudhuri-Hocquenghem [BCH] codes
• CPC Class Codes: H03M 13/251 with block coding
• CPC Class Codes: H03M 13/255 with Low Density Parity Check [LDPC] codes
• CPC Class Codes: H03M 5/18 two levels being symmetrical with respect to the third level, i.e. balanced bipolar ternary code
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0058 Block-coded modulation
• CPC Class Codes: H04L 25/4917 using multilevel codes
• CPC Class Codes: H04L 27/36 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/364 Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels

Abstract

A method includes receiving multiple bits to be transmitted. The method also includes applying a first binary alphabet polar code to a first subset of the multiple bits to generate first encoded bits. The first encoded bits are associated with a first bit level of a multilevel coding scheme. The method further includes generating one or more symbols using the first encoded bits and bits associated with a second bit level of the multilevel coding scheme. The first binary alphabet polar code is associated with a first coding rate. In addition, the method could include applying a second binary alphabet polar code to a second subset of the multiple bits to generate second encoded bits. The second encoded bits are associated with the second bit level. The second binary alphabet polar code is associated with a second coding rate such that the bit levels have substantially equal error rates.

Claims

1. A method comprising:

receiving multiple bits to be transmitted;

applying a first binary alphabet polar code to a first subset of the multiple bits to generate first encoded bits, the first encoded bits associated with a first bit level of a multilevel coding scheme; and

generating one or more symbols using the first encoded bits and bits associated with a second bit level of the multilevel coding scheme;

wherein the first binary alphabet polar code is associated with a first coding rate.

2. The method of claim 1, further comprising:

applying a second binary alphabet polar code to a second subset of the multiple bits to generate second encoded bits, the second encoded bits associated with the second bit level of the multilevel coding scheme.

3. The method of claim 2, wherein the second binary alphabet polar code is associated with a second coding rate such that the first and second bit levels have substantially equal error rates.

4. The method of claim 1, wherein:

the first bit level represents one or more least significant bits of the one or more symbols; and

the second bit level represents one or more other bits of the one or more symbols.

5. The method of claim 1, wherein the first binary alphabet polar code corresponds to one bit in a bit-to-symbol mapping for an in-phase (I) direction and one bit in the bit-to-symbol mapping for a quadrature (Q) direction.

6. The method of claim 1, wherein the first binary alphabet polar code corresponds to multiple bits in a bit-to-symbol mapping for an in-phase (I) direction and multiple bits in the bit-to-symbol mapping for a quadrature (Q) direction.

7. The method of claim 1, wherein generating the one or more symbols comprises using a symbol mapping of bits to symbols, the symbol mapping providing an increasing Euclidian distance between symbols having a common value at a specific bit position as the bit level increases assuming each bit at each lower bit level is decoded correctly.

8. An apparatus comprising:

a first encoder configured to (i) receive multiple bits to be transmitted and (ii) apply a first binary alphabet polar code to a first subset of the multiple bits to generate first encoded bits, the first encoded bits associated with a first bit level of a multilevel coding scheme; and

a symbol generator configured to map the first encoded bits and bits associated with a second bit level of the multilevel coding scheme to one or more symbols for transmission;

wherein the first binary alphabet polar code is associated with a first coding rate.

9. The apparatus of claim 8, further comprising:

a second encoder configured to apply a second binary alphabet polar code to a second subset of the multiple bits to generate second encoded bits, the second encoded bits associated with the second bit level of the multilevel coding scheme.

10. The apparatus of claim 9, wherein the second binary alphabet polar code is associated with a second coding rate such that the first and second bit levels have substantially equal error rates.

11. The apparatus of claim 8, wherein:

the first bit level represents one or more least significant bits of the one or more symbols; and

the second bit level represents one or more other bits of the one or more symbols.

12. The apparatus of claim 8, wherein the first binary alphabet polar code corresponds to one bit in a bit-to-symbol mapping for an in-phase (I) direction and one bit in the bit-to-symbol mapping for a quadrature (Q) direction.

13. The apparatus of claim 8, wherein the first binary alphabet polar code corresponds to multiple bits in a bit-to-symbol mapping for an in-phase (I) direction and multiple bits in the bit-to-symbol mapping for a quadrature (Q) direction.

14. The apparatus of claim 8, wherein the symbol generator is configured to use a symbol mapping of bits to symbols, the symbol mapping providing an increasing Euclidian distance between symbols having a common value at a specific bit position as the bit level increases assuming each bit at each lower bit level is decoded correctly.

15. A method comprising:

applying a first binary alphabet polar code to first decoding information associated with one or more symbols to generate first decoded bits, the first decoding information associated with a first bit level of a multilevel coding scheme; and

outputting the first decoded bits and bits associated with a second bit level of the multilevel coding scheme;

wherein the first binary alphabet polar code is associated with a first coding rate.

16. The method of claim 15, further comprising:

applying a second binary alphabet polar code to second decoding information associated with the one or more symbols to generate second decoded bits, the second decoded bits associated with the second bit level.

17. The method of claim 16, wherein the second binary alphabet polar code is associated with a second coding rate such that the first and second bit levels have substantially equal error rates.

18. The method of claim 17, further comprising:

calculating log-likelihood ratio (LLR) values associated with the bit levels using the one or more symbols to generate the first and second decoding information;

wherein the LLR values associated with the second bit level are calculated using the first decoded bits.

19. The method of claim 16, further comprising:

applying a third decoding scheme to third decoding information associated with the one or more symbols to generate third decoded bits, the third decoding information associated with a third bit level.

20. An apparatus comprising:

a first decoder configured to apply a first binary alphabet polar code to first decoding information associated with one or more symbols to generate first decoded bits, the first decoding information associated with a first bit level of a multilevel coding scheme, the multilevel coding scheme having a second bit level;

wherein the first binary alphabet polar code is associated with a first coding rate.

21. The apparatus of claim 20, further comprising:

a second decoder configured to apply a second binary alphabet polar code to second decoding information associated with the one or more symbols to generate second decoded bits, the second decoded bits associated with the second bit level.

22. The apparatus of claim 21, wherein the second binary alphabet polar code is associated with a second coding rate such that the first and second bit levels have substantially equal error rates.

23. The apparatus of claim 21, further comprising:

log-likelihood ratio (LLR) calculators configured to calculate log-likelihood ratio (LLR) values associated with the bit levels using the one or more symbols to generate the first and second decoding information;

wherein the LLR values for the second bit level are calculated using the first decoded bits.

24. The apparatus of claim 21, further comprising:

a third decoder configured to apply a third decoding scheme to third decoding information associated with the one or more symbols to generate third decoded bits, the third decoding information associated with a third bit level.

25. The apparatus of claim 20, wherein the first decoder comprises one of:

a successive cancellation decoder, a list decoder, and a belief-propagation decoder.

26. A method comprising:

identifying a target error rate associated with a multilevel coding scheme, the multilevel coding scheme having multiple bit levels;

identifying an effective signal-to-noise ratio (SNR) at each of the bit levels, the effective SNR based on a symbol mapping rule used to map bits into symbols;

identifying a code rate at each bit level using the target error rate and the SNR at that bit level; and

selecting, at one or more of the bit levels, at least one polar code having at least one of the identified code rates so that an overall error rate of each bit level is substantially equal.