REDUCED-STAGE POLAR DECODING

• US 20180054278A1
• Filed: 07/17/2017
• Published: 02/22/2018
• Est. Priority Date: 08/19/2016
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: SHI, WUXIAN, GE, YIQUN
• Granted Patent: US 10,447,435 B2
• Time in Patent Office: Days
• CPC Class Codes: H03M 13/13 Linear codes
• CPC Class Codes: H03M 13/45 Soft decoding, i.e. using symbol reliability information H03M13/41 takes precedence
• CPC Class Codes: H03M 13/6502 Reduction of hardware complexity or efficient processing
• CPC Class Codes: H03M 13/6505 Memory efficient implementations
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0052 Realisations of complexity reduction techniques, e.g. pipelining or use of look-up tables
• CPC Class Codes: H04L 1/0058 Block-coded modulation
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

In reduced-stage polar decoding, a received word that is based on an N-bit codeword of a polar code is decoded using fewer than log₂N Log Likelihood Ratio (LLR) stages. Decoding uses a reduced stage decoding configuration. In an embodiment, such a configuration includes at least one higher-order LLR stage with nodes implementing functions that are based on a combination of lower-order polar code kernels.

Claims

1. A method comprising:

receiving a word that is based on an N-bit codeword of a polar code; and

decoding the received word using fewer than log₂N Log Likelihood Ratio (LLR) stages.

2. The method of claim 1, wherein the LLR stages comprise a higher-order LLR stage with nodes implementing functions based on a combination of lower-order polar code kernels.

3. The method of claim 2, wherein the lower-order polar code kernels are 2-by-2 polar code kernels.

4. The method of claim 3, wherein the functions comprise one or more of the following A, B, C, and D functions or equivalent functions consistent therewith.

A-function:

llr0′

=sgn(llr0)·

sgn(llr1)·

sgn(llr2)·

sgn(llr3)·

min(|llr0|,|llr1|,|llr2|,|llr3|)

B-function;

llr1′

=sgn(llr1)·

sgn(llr3)·

min(|llr1|,|llr3|)+sgnb(û

₀)sgn(llr0)·

sgn(llr2)·

min(|llr0|,|llr2|), or equivalently

5. The method of claim 2, wherein the functions comprise one or more of the following A8 functions or equivalent functions consistent therewith:

A8_0 function;

llr0′

=sgn(llr0)*sgn(llr1)*sgn(llr2)*sgn(llr3)*sgn(llr4)*sgn(llr5)*sgn(llr6)*sgn(llr7)*min{|llr0|, |llr1|,|llr2|,|llr3|,|llr4|,|llr5|,|llr6|,|llr7|}

A8_1 function;

llr1′

=sgnb(û

₀)*sgn(llr0)*sgn(llr2)*sgn(llr4)*sgn(llr6)*min{|llr0|,|llr2|,|llr4|,|llr6|}+sgn(llr1)*sgn(llr3)*sgn(llr5)*sgn(llr7)*min{|llr1|,|llr3|,|llr5|,|llr7|}

A8_2 function;

temp1=sgnb(û

₀⊕

û

₁)·

[sgn(llr0)·

sgn(llr4)·

min(|llr0|,|llr4|)]+sgn(llr2)·

sgn(llr6)·

min(|llr2|,|llr6|)

temp2=sgnb(û

₁)·

[sgn(llr1)·

sgn(llr5)·

min(|llr1|,|llr5|)]+sgn(llr3)·

sgn(llr7)·

min(|llr3|,|llr7|)

llr2′

=sgn(temp1)·

sgn(temp2)·

min(|temp1|,|temp2|)

A8_3 function;

6. The method of claim 1, wherein the LLR stages comprise an LLR stage with f and g nodes, which respectively apply the following functions or equivalent functions consistent therewith:

f-function;

llr0′

=sgn(llr0)·

sgn(llr1)·

min(|llr0|,|llr1|)

g-function;

llr1′

=llr1+sgnb(û

₀)·

llr0,

where

û

₀ is an estimated bit value;

llrx are input LLR values;

llrx′

are output LLR values; and

min( ) is minimum.

7. The method of claim 1, wherein the decoding comprises List decoding.

8. An apparatus comprising:

a receiver for receiving a word that is based on an N-bit codeword of a polar code; and

a decoder, coupled to the receiver, to decode the received word in fewer than log₂N Log Likelihood Ratio (LLR) stages.

9. The apparatus of claim 8, wherein the LLR stages comprise a higher-order LLR stage with nodes implementing functions based on a combination of lower-order polar code kernels.

10. The apparatus of claim 8, wherein the lower-order polar code kernels are 2-by-2 polar code kernels.

11. The apparatus of claim 10, wherein the functions comprise one or more of the following A, B, C, and D functions or equivalent functions consistent therewith:

A-function;

llr0′

=sgn(llr0)·

sgn(llr1)·

sgn(llr2)·

sgn(llr3)·

min(|llr0|,|llr1|,|llr2|,|llr3|)

B-function;

llr1′

=sgn(llr1)·

sgn(llr3)·

min(|llr1|,|llr3|)+sgnb(û

₀)sgn(llr0)·

sgn(llr2)·

min(|llr0|,|llr2|), or equivalently

12. The apparatus of claim 9, wherein the functions comprise one or more of the following A8 functions or equivalent functions consistent therewith:

A8_0 function;

llr0′

=sgn(llr0)*sgn(llr1)*sgn(llr2)*sgn(llr3)*sgn(llr4)*sgn(llr5)*sgn(llr6)*sgn(llr7)*min{|llr0|, llr1|,|llr2|,|llr3|,|llr4|, |llr5|,|llr6|,|llr7|}

A8_1 function;

llr1′

=sgnb(û

₀)*sgn(llr0)*sgn(llr2)*sgn(llr4)*sgn(llr6)*min{|llr0|,|llr2|,|llr4|,|llr6|}+sgn(llr1)*sgn(llr3)*sgn(llr5)*sgn(llr7)*min{|llr1|,|llr3|,|llr5|,|llr7|}

A8_2 function;

temp1=sgnb(û

₀⊕

û

₁)·

[sgn(llr0)·

sgn(llr4)·

min(|llr0|,|llr4|)]+sgn(llr2)·

sgn(llr6)·

min(|llr2|,|llr6|)

temp2=sgnb(û

₁)·

[sgn(llr1)·

sgn(llr5)·

min(|llr5|)]+sgn(llr3)·

sgn(llr7)·

min(|llr3|,|llr7|)

llr2′

=sgn(temp1)·

sgn(temp2)·

min(|temp1|,|temp2|)

A8_3 function;

13. The apparatus of claim 8, wherein the LLR stages comprise an LLR stage with f and g nodes, which respectively apply the following functions or equivalent functions consistent therewith:

f-function;

llr0′

=sgn(llr0)·

sgn(llr1)·

min(|llr0|,|llr1|)

g-function;

llr1′

=llr1+sgnb(û

₀)·

llr0,

where

û

₀ is an estimated bit value;

llrx are input LLR values;

llrx′

are output LLR values; and

min( ) is minimum.

14. The apparatus of claim 8, wherein the decoder comprises a List decoder.

15. User equipment comprising the apparatus of claim 8.

16. Communication network equipment comprising the apparatus of claim 8.