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