Method and apparatus for generating hybrid polar code
Embodiments of the present invention provide a method and an apparatus for generating a hybrid Polar code. The method includes: obtaining a first matrix of N×N and a sequence that includes N bits, N rows of the first matrix correspond to the N bits in the sequence in a one-to-one manner, and N is a positive integer; determining reliability of the N bits, and determining the weight of each row in the N rows of the first matrix; selecting, according to the reliability of the N bits and the weight of the N rows of the first matrix, K bits among the N bits as information bits, or selecting, according to the reliability of the N bits and the weight of the N rows of the first matrix, K rows of the first matrix to construct a second matrix of K×N used for encoding.
1. A method for transmitting data by a communication apparatus, comprising:
obtaining, by the communication apparatus, a first sequence, wherein the first sequence comprises K information bits, and K is a positive integer;
generating, by the communication apparatus, a second sequence u 1 N , wherein the second sequence u 1 N comprises N bits, N is an integer power of 2 and is greater than K, and wherein K bit-positions of the second sequence u 1 N are occupied by the K information bits of the first sequence;
encoding, by the communication apparatus, the second sequence u 1 N according to an encoding process of x 1 N =u 1 N G N , wherein G N is a Polar code generating matrix of N rows ×N columns, and x 1 N is an N-bit encoded sequence output by the encoding process; and
transmitting, by the communication apparatus, the encoded sequence x 1 N to a receiver;
wherein the i th row of the N×N matrix corresponds to the i th bit of the second sequence u 1 N , i=1, 2, . . . , N;
wherein the K bit-positions in the second sequence u 1 N , that are occupied by the K information bits of the first sequence, are selected according to reliability of the bit-positions of the second sequence u 1 N and weight of the rows of the N×N matrix that correspond to the bit-positions of the second sequence u 1 N .
2. The method according to claim 1 , wherein the K bit-positions in the second sequence, that are occupied by the K information bits of the first sequence, are selected, in descending order of reliability, from the N bit-positions of the second sequence, and wherein the weight of rows in the N×N matrix that correspond to the K selected bit-positions are greater than or equal to a weight threshold.
3. The method according to claim 2 , wherein
the weight threshold is determined according to a minimum code distance requirement.
4. The method according to claim 1 , wherein the K bit-positions in the second sequence, that are occupied by the K information bits of the first sequence, are selected by:
excluding one or more bits of the second sequence, wherein the weight of rows in the N×N matrix that correspond to bit-positions of the excluded bits in the second sequence are smaller than a weight threshold; and
selecting, in descending order of the reliability, K bit-positions among the remaining bits of the second sequence for carrying the K information bits of the first sequence.
5. The method according to claim 1 , wherein the reliability of bit-positions in the second sequence is measured by
capacity of bit-positions in the second sequence, wherein reliability of a bit-position with higher capacity is higher.
6. The method according to claim 1 , wherein the reliability of bit-positions in the second sequence is measured by a Bhattacharyya parameter of the bit-position, wherein reliability of a bit-position with a smaller Bhattacharyya parameter is higher.
7. The method according to claim 1 , wherein the reliability of each bit-position in the second sequence is measured by an error probability of the bit-position, wherein a bit-position with a smaller error probability has a higher reliability.
8. The method according to claim 1 , wherein the Polar code generating matrix G N is:
G N =B N F ⊗n or
G N =F ⊗n ,
wherein B N is a bit reversal matrix, F ⊗n is a kronecker power of F, and
F
=
[
1
0
1
1
]
.
9. The method according to claim 1 , wherein remaining N−K bit-positions in the second sequence are set to a preset value.
10. The method according to claim 1 , wherein when more than one bit-positions in the second sequence correspond to more than one rows of the N×N matrix that have same weight, one or more bit-positions of the second sequence are selected for carrying the information bits of the first sequence in a descending order of reliability of the bit-positions.
11. A communication apparatus, comprising:
a transmitting circuit;
a processor and a memory storing program instructions for execution by the processor, wherein by executing the program instructions, the processor is configured to:
obtain a first sequence, wherein the first sequence comprises K information bits, and K is a positive integer;
generate a second sequence u 1 N , wherein the second sequence u 1 N comprises N bits, N is an integer power of 2 and is greater than K, and wherein K bit-positions of the second sequence u 1 N are occupied by the K information bits of the first sequence;
encode the second sequence u 1 N according to an encoding process of x 1 N =u 1 N G N , wherein G N is a Polar code generating matrix of N rows×N columns, and x 1 N is an N-bit encoded sequence output by the encoding process; and
cause the transmitting circuit to transmit the encoded sequence x 1 N to a receiver;
wherein the i th row of the N×N matrix corresponds to the i th bit of the second sequence u 1 N , i=1, 2, . . . , N;
wherein the K bit-positions in the second sequence u 1 N , that are occupied by the K information bits of the first sequence, are selected according to the reliability of the bit-positions of the second sequence u 1 N and weight of the rows of the N×N matrix that correspond to the bit-positions of the second sequence u 1 N .
12. The communication apparatus according to claim 11 , wherein the K bit-positions in the second sequence, that are occupied by the K information bits of the first sequence, are selected, in descending order of the reliability, from the N bit-positions of the second sequence, and wherein the weight of rows in the N×N matrix that correspond to the K selected bit-positions are greater than or equal to a weight threshold.
13. The communication apparatus according to claim 12 , wherein the weight threshold is determined according to a minimum code distance requirement.
14. The communication apparatus according to claim 12 , wherein the weight threshold is determined according to a minimum code distance requirement.
15. The communication apparatus according to claim 11 , wherein the K bit-positions in the second sequence, that are occupied by the K information bits of the first sequence, are selected by:
excluding one or more bits of the second sequence, wherein the weight of rows in the N×N matrix that correspond to bit-positions of the excluded bits in the second sequence are smaller than a weight threshold;
and
selecting, in descending order of the reliability, K bit-positions among the sorted remaining bits of the second sequence for carrying the K information bits of the first sequence.
16. The communication apparatus according to claim 11 , wherein the reliability of each bit-position in the second sequence is measured by capacity of the bit-positions in the second sequence, wherein reliability of a bit-position with higher capacity is higher.
17. The communication apparatus according to claim 11 , wherein the reliability of each bit-position in the second sequence is measured by a Bhattacharyya parameter of the bit-position, wherein reliability of bit-position with a smaller Bhattacharyya parameter is a higher.
18. The communication apparatus according to claim 11 , wherein the reliability of each bit-position of in the second sequence is measured by an error probability of the bit-position, wherein a reliability of bit-position with a smaller error probability is higher.
19. The communication apparatus according to claim 11 , wherein the Polar code generating matrix G N is:
G N =B N F ⊗n or
G N =F ⊗n ,
wherein B N is a bit reversal matrix, F ⊗n is a kronecker power of F, and
F
=
[
1
0
1
1
]
.
20. The communication apparatus according to claim 11 , wherein remaining N−K positions of the second sequence are set to a preset value.
21. The communication apparatus according to claim 11 , wherein when more than one bit-positions in the second sequence correspond to more than one rows of the N×N matrix that have same weight, one or more bit-positions of the second sequence are selected for carrying the information bits of the first sequence in a descending order of reliability of the bit-positions.