Polar code transmission method and apparatus
This application discloses a transmission method, a transmission apparatus, and a communications device. The transmission method includes: performing polar encoding on a bit sequence, to obtain an encoded sequence, where the bit sequence includes control information and a cyclic redundancy check CRC sequence; fragmenting the encoded sequence, to obtain n encoded subsequences, where n is an integer, and n>0; and scrambling the n encoded subsequences by using n scrambling sequences respectively, to obtain n scrambled sequences. In the transmission method, the n scrambling sequences are newly defined based on encoding and decoding features of a polar code, and the n scrambling sequences additionally carry ┌log 2 n┐-bit information. According to the foregoing encoding method, signaling overheads are reduced.
1. A transmission method, applied to a network device and comprising:
performing polar encoding on a bit sequence, to obtain an encoded sequence, wherein the bit sequence comprises control information and a cyclic redundancy check (CRC) sequence;
fragmenting the bit sequence, after performing the polar encoding, to obtain n encoded subsequences, wherein n is an integer, and n>0;
scrambling the n encoded subsequences by using n scrambling sequences respectively, to obtain n scrambled sequences;
performing modulation and mapping operations on the n scrambled sequences; and
sending the n scrambled sequences after performing the modulation and mapping operations,
wherein the scrambling the n encoded subsequences by using the n scrambling sequences respectively comprises:
performing an exclusive-OR operation on an odd-numbered vector and an even-numbered vector of each of the n encoded subsequences by using each of the n scrambling sequences.
2. The method according to claim 1 , wherein the n scrambling sequences carry ┌log 2 n┐-bit information.
3. The method according to claim 1 , wherein the control information is a master information block (MIB).
4. A transmission method, applied to a terminal and comprising:
receiving, by the terminal, a symbol sequence, wherein the symbol sequence is obtained by a network device after the network device encodes control information by using a polar code, and scrambles, modulates, and maps encoded control information;
demapping and demodulating, by the terminal, the symbol sequence, to obtain an encoded sequence;
selecting, by the terminal, at least one encoded subsequence from the encoded sequence;
performing, by the terminal, polar decoding on the at least one encoded subsequence, to obtain a bit sequence, wherein the bit sequence comprises the control information and a Cyclic Redundancy Check (CRC) sequence; and
performing, by the terminal, a descrambling operation on the bit sequence by using at least one descrambling sequence, and performing a CRC check on a descrambled bit sequence, to obtain the control information and timing information if the CRC check succeeds,
wherein the performing, by the terminal, the polar decoding on the at least one encoded subsequence comprises:
decoding, by the terminal, one encoded subsequence and
wherein the performing, by the terminal, the descrambling operation on the bit sequence by using the at least one descrambling sequence, and the performing the CRC check on the descrambled bit sequence comprises:
performing, by the terminal, the descrambling operation on the bit sequence by using each of four descrambling sequences, and further performing CRC check on the descrambled bit sequence obtained each time, to obtain the control information if the CRC check succeeds; and
obtaining, by the terminal, the timing information based on a sequence number of a descrambling sequence corresponding to the successful CRC check.
5. The method according to claim 4 , wherein the control information is a master information block (MIB).
6. A transmission apparatus, comprising:
a processor; and
a memory storing instructions that when executed configure the processor to perform steps comprising:
receiving a symbol sequence, wherein the symbol sequence is obtained by a network device after the network device encodes control information by using a polar code, and scrambles, modulates, and maps encoded control information;
demapping and demodulating the symbol sequence, to obtain an encoded sequence;
selecting at least one encoded subsequence from the encoded sequence;
performing polar decoding on the at least one encoded subsequence, to obtain a bit sequence, wherein the bit sequence comprises the control information and a Cyclic Redundancy Check (CRC) sequence;
performing a descrambling operation on the bit sequence by using at least one descrambling sequence; and
performing a CRC check on the bit sequence after performing the descrambling operation, to obtain the control information and timing information if the CRC check succeeds,
wherein the performing the polar decoding on the at least one encoded subsequence comprises:
decoding one encoded subsequence; and
wherein the performing the descrambling operation on the bit sequence and the performing the CRC check on the bit sequence, after performing the descrambling operation comprises:
performing a descrambling operation on the bit sequence by using each of four descrambling sequences, and further performing a CRC check on a descrambled bit sequence obtained each time, to obtain the control information if the CRC check succeeds; and
obtaining the timing information based on a sequence number of a descrambling sequence corresponding to the successful CRC check.
7. The apparatus according to claim 6 , wherein the control information is a master information block (MIB).