Polar code rate matching method and apparatus

1. A polar code rate matching method, comprising:

performing, by a rate matching apparatus, bit reversal order (BRO) interleaving on a polar code, to obtain interleaved bits, a length of input bits of the rate matching apparatus is N, wherein N is a positive integer;

mapping, by the rate matching apparatus, an i th input bit onto a Π(i+Δ mod N) th output bit, wherein i=0, 1, . . . , and N−1, Δ is an offset, Π(i) is obtained from BRO M (j), wherein the BRO M (j) indicates that a bit reversal order operation is performed on an index j, and M is a positive integer indicating a size of BRO M (j);

determining, by the rate matching apparatus, based on the interleaved bits, a rate-matched output sequence;

arranging, by the rate matching apparatus, the interleaved bits into the rate-matched output sequence to produce a rate-matched output sequence of bits; and

transmitting, by the rate matching apparatus, the rate-matched output sequence of bits.

2. The method according to claim 1 , wherein:

Π(i) is defined as follows: Π B (j)=BRO M (j), wherein

j=0, 1 . . . , and B−1, and B indicates a size of Π B (j).

3. The method according to claim 1 , wherein:

Π(i) is obtained by means of pruning by Π B (j); and

Π B (j)=2 M (j mod J)+BRO M (└j/J┘), wherein

j=0, 1, . . . , B−1, B indicates a size of the rate matching apparatus Π B ( ) B=M×J, and J is a positive integer.

4. The method according to claim 1 , wherein determining, based on the interleaved bits, a rate-matched output sequence comprises:

writing the interleaved bits or reversed bits of the interleaved bits into a circular buffer;

determining a start location of the rate-matched output sequence in the circular buffer according to a redundancy version; and

reading the rate-matched output sequence from the circular buffer according to the start location.

5. The method according to claim 1 , wherein determining, based on the interleaved bits, a rate-matched output sequence comprises:

sequentially intercepting the interleaved bits or reversed bits of the interleaved bits to obtain the rate-matched output sequence; or

repeatedly extracting the interleaved bits or reversed bits of the interleaved bits to obtain the rate-matched output sequence.

6. A wireless communications apparatus, comprising:

a polar code encoder;

a rate matching apparatus, configured to:

perform BRO interleaving on a polar code output by the polar code encoder, to obtain interleaved bits and map an i th input bit onto a Π(i+Δ mod N) th output bit, wherein i=0, 1, . . . , and N−1, Δ is an offset, Π(i) is obtained from BRO M (j), BRO M (j) indicates that a bit reversal order operation is performed on an index j, and M is a positive integer indicating a size of BRO M (j), a length of input bits of the rate matching apparatus is N,

determine, based on the interleaved bits, a rate-matched output sequence, and

arrange the interleaved bits into the rate-matched output sequence to produce a rate-matched output sequence of bits; and

a transmitter, configured to transmit the rate-matched output sequence of bits.

7. The wireless communications apparatus according to claim 6 , wherein the rate matching apparatus is configured to:

write the interleaved bits or reversed bits of the interleaved bits into a circular buffer;

determine a start location of the rate-matched output sequence in the circular buffer according to a redundancy version; and

read the rate-matched output sequence from the circular buffer according to the start location.

8. The wireless communications apparatus according to claim 6 , wherein the rate matching apparatus is configured to:

sequentially intercept the interleaved bits or reversed bits of the interleaved bits to obtain the rate-matched output sequence; or

repeatedly extract the interleaved bits or reversed bits of the interleaved bits to obtain the rate-matched output sequence.

9. An apparatus for interleaving, comprising:

a bit reversal order (BRO) interleaver processor, configured to perform BRO interleaving on a polar code output by a polar code encoder, to obtain interleaved bits, and map an i th input bit onto a Π(i+Δ mod N) th output bit, wherein i=0, 1, . . . , and N−1, Δ is an offset, Π(i) is obtained from BRO M (j), BRO M (j) indicates that a bit reversal order operation is performed on an index j, and M is a positive integer indicating a size of BRO M (j), a length of input bits of the BRO interleaver is N;

a circular buffer, configured to store the interleaved bits or reversed bits of the interleaved bits; and

a transmitter, configured to transmit the interleaved bits or reversed bits.

10. The apparatus for interleaving according to claim 9 , wherein:

Π(i) is defined as follows: Π B (j)=BRO M (j), wherein

j=0, 1, . . . , and B−1, and B indicates a size of Π B (j).

11. The apparatus for interleaving according to claim 9 , wherein:

Π(i) is obtained by means of pruning by Π B (j); and

Π B (j)=2 M (j mod J)+BRO M (└j/J┘), wherein

j=0, 1, . . . , B−1, B indicates a size of the interleaver Π B (j), B=M×J, and J is a positive integer.