Method for transmitting data by using polar coding in wireless access system

Abstract

The present invention relates to data transmission/reception methods using a polar coding scheme, and devices for supporting same. The method for transmitting data by using polar coding in a wireless access system, according to one embodiment of the present invention, may comprise the steps of deriving Bhattacharyya parameters according to data bits input for finding noise-free channels among equivalent channels; allocating data payloads comprising data bits and cyclic redundancy check (CRC) bits to the found noise-free channels; inputting the data payloads into a polar encoder; and transmitting code bits output by the polar encoder, wherein the CRC bits may be allocated to better noise-free channels, among the noise-free channels indicated by the Bhattacharyya parameters, than the data bits.

The invention claimed is: 
     
       1. A method for transmitting data by using polar coding in a wireless access system, the method comprising:
 inputting first data bits to a polar encoder;   deriving Bhattacharyya parameters in accordance with the first data bits to discover noise free channels from equivalent channels, wherein the equivalent channels are defined for each of the first data bits;   allocating a data payload including second data bits and cyclic redundancy check (CRC) bits to the discovered noise free channels, wherein the number of the discovered noise free channels corresponds to a total number of bits of the data payload;   performing rate matching for the data payload based on a size of the polar encoder and a size of the data payload; and   transmitting code bits output from the polar encoder through the noise free channels,   wherein the CRC bits are allocated to noise free channels starting from a noise free channel having a lowest error probability among the discovered noise free channels and the second data bits are allocated to the other noise free channels among the discovered noise free channels according to the Bhattacharyya parameters.   
     
     
       2. The method according to  claim 1 , further comprising:
 transmitting size information indicating the size of the data payload and information on a coding rate of the polar encoder to a receiver.   
     
     
       3. The method according to  claim 1 , wherein the rate matching is performed by puncturing or repeating the data payload in accordance with the size of the polar encoder. 
     
     
       4. The method according to  claim 3 , further comprising:
 generating a generator matrix for the polar encoder by puncturing one or more specific columns of a mother generator matrix based on the size of the data payload when the size of the code block of the polar encoder is greater than the size of the data payload when performing rate matching.   
     
     
       5. The method according to  claim 4 , wherein the one or more specific columns are selected starting from a column having a lowest weight value. 
     
     
       6. The method according to  claim 4 , wherein the one or more specific columns are selected considering a minimum distance set based on an index of a noise free channel to which the data bits are allocated. 
     
     
       7. The method according to  claim 4 , wherein the one or more specific columns are selected based on a priority according to a column index. 
     
     
       8. The method according to  claim 3 , further comprising:
 generating a generator matrix for the polar encoder by repeating one or more specific columns of a mother generator matrix based on the size of the data payload when the size of the code block of the polar encoder is smaller than the size of the data payload when performing rate matching.   
     
     
       9. The method according to  claim 8 , wherein the one or more specific columns are selected starting from a column having a highest weight value. 
     
     
       10. A device for a wireless communication system, the device comprising:
 at least one processor; and   at least one computer memory storing at least one program which causes the at least one processor to perform operations comprising:
 allocating a payload of K bits to K predetermined input bits among N input bits for a polar code of size N, where K is a positive integer not greater than N; 
 generating encoded bits based on the N input bits and the polar code; and 
 transmitting the encoded bits to a receiving device, 
 wherein the payload includes L data bits and M cyclic redundancy check (CRC) bits, where L+M=K, and L and M are positive integers, and 
 wherein the M CRC bits are allocated to M most reliable input bits among the K predetermined input bits.  
   
     
     
       11. The device according to claim 10, wherein the operations further comprise:
 allocating 0 to each of N-K input bits other than the K predetermined input bits among the N input bits for the polar code,   wherein the K predetermined input bits have higher reliability than the N-K input bits.    
     
     
       12. A non-transitory computer readable storage medium storing at least one program that cause at least one processor to perform operations comprising:
 allocating a payload of K bits to K predetermined input bits among N input bits for a polar code of size N, where K is a positive integer not greater than N;   generating encoded bits based on the N input bits and the polar code; and   transmitting the encoded bits to a receiving device,   wherein the payload includes L data bits and M cyclic redundancy check (CRC) bits, where L+M=K, and L and M are positive integers, and   wherein the M CRC bits are allocated to M most reliable input bits among the K predetermined input bits.    
     
     
       13. The non-transitory computer readable storage medium according to claim 12, wherein the operations further comprise:
 allocating 0 to each of N-K input bits other than the K predetermined input bits among the N input bits for the polar code,   wherein the K predetermined input bits have higher reliability than the N-K input bits.    
     
     
       14. A method for receiving data by using polar coding in a wireless communication system, the method comprising:
 receiving encoded bits from a transmitting device; and   decoding the encoded bits to obtain a payload of K bits based on a polar code of size N,   wherein the encoded bits are decoded based on a mapping relationship between the payload of K bits and K predetermined input bits among N input bits for the polar code, where K is a positive integer not greater than N,   wherein the payload includes L data bits and M cyclic redundancy check (CRC) bits, where L+M=K, and L and M are positive integers, and   wherein the mapping relationship comprises: mapping the M CRC bits to M most reliable input bits among the K predetermined input bits.    
     
     
       15. The method according to claim 14, wherein the mapping relationship further comprises:
 mapping 0 to each of N-K input bits other than the K predetermined input bits among the N input bits for the polar code,   wherein the K predetermined input bits have higher reliability than the N-K input bits.