A rate matching method including: determining a receiving capability of a receive end, where the receiving capability is used to indicate a maximum data processing volume of the receive end in a first transmission time, and/or the receiving capability is used to indicate a maximum data buffer volume of the receive end in a first transmission time; the first transmission time is used to transmit a first transport block to which a first code block belongs; determining N.sub.CB based on the receiving capability, where N.sub.CB represents a code block size used for rate matching; performing rate matching on the first code block based on N.sub.CB. The receive end can adjust, based on a processing capability and/or a buffer capability that are/is of the receive end in a period of time, the code block size used for rate de-matching, to avoid insufficiency in processing capability and/or buffer overflow at the receive end.

Systems, methods, and instrumentalities are disclosed for interleaving coded bits. A wireless transmit/receive unit (WTRU) may generate a plurality of polar encoded bits using polar encoding. The WTRU may divide the plurality of polar encoded bits into sub-blocks of equal size in a sequential manner. The WTRU may apply sub-block wise interleaving to the sub-blocks using an interleaver pattern. The sub-blocks associated with a subset of the sub-blocks may be interleaved, and sub-blocks associated with another subset of the sub-blocks may not be interleaved. The sub-block wise interleaving may include applying interleaving across the sub-blocks without interleaving bits associated with each of the sub-blocks. The WTRU may concatenate bits from each of the interleaved sub-blocks to generate interleaved bits, and store the interleaved bits associated with the interleaved sub-blocks in a circular buffer. The WTRU may select a plurality of bits for transmission from the interleaved bits.

Various aspects of the disclosure relate to retransmission techniques for communication of information (e.g., for wireless communication). In some aspects, if a device's first transmission including punctured encoded data fails, the device's second transmission (e.g., in response to a NAK) may involve transmitting the punctured bits. In some aspects, the coding rate used for encoding the data for the first transmission is selected to meet an error rate (e.g., a block error rate) for the second transmission. The second transmission may also include at least some of the encoded data. In some aspects, the puncturing may be performed according to a puncture pattern that is generated based on bit error probabilities of bit positions for encoded data.

A polar encoding and decoding method and apparatus are provided. The method includes: obtaining K to-be-encoded bits; selecting K sequence numbers from a first sequence, where the to-be-encoded bits are placed on polar channels corresponding to the K sequence numbers; and performing polar code encoding on the K to-be-encoded bits to obtain encoded bits, where the first sequence includes sequence numbers of N polar channels, and the first sequence is one or a subsequence of a related sequence. This technical solution is applicable to a short message communication system of a BeiDou satellite. The method can effectively improve performance of the communication system and reduce complexity.

A polar code encoding method includes obtaining, by an encoding apparatus, to-be-encoded bits, a mother code length, and a first sequence. The first sequence includes sequence numbers of polarized subchannels. The sequence numbers of the polarized subchannels are arranged in the first sequence based on reliability of the polarized subchannels. The method also includes determining, based on the first sequence, polarized subchannels used to contain the to-be-encoded bits, and performing polarization encoding on the to-be-encoded bits to obtain an encoded bit sequence. The method further includes performing rate matching on the encoded sequence to obtain a rate-matched sequence. The method additionally includes outputting the rate-matched sequence.

The present disclosure relates to polar code rate matching methods, apparatuses, and mediums. One example method includes obtaining K to-be-coded bits and a mother code length N, where N=2.sup.n performing polar code encoding on the K to-be-coded bits based on the mother code length N to obtain an encoded bit sequence, performing rate matching on the polar-encoded bit sequence based on a rate matching sequence to obtain a rate matched sequence with a length of M, and outputting the rate matched sequence.

Systems, methods, and instrumentalities are disclosed for interleaving coded bits. A wireless transmit/receive unit (WTRU) may generate a plurality of polar encoded bits using polar encoding. The WTRU may divide the plurality of polar encoded bits into sub-blocks of equal size in a sequential manner. The WTRU may apply sub-block wise interleaving to the sub-blocks using an interleaver pattern. The sub-blocks associated with a subset of the sub-blocks may be interleaved, and sub-blocks associated with another subset of the sub-blocks may not be interleaved. The sub-block wise interleaving may include applying interleaving across the sub-blocks without interleaving bits associated with each of the sub-blocks. The WTRU may concatenate bits from each of the interleaved sub-blocks to generate interleaved bits, and store the interleaved bits associated with the interleaved sub-blocks in a circular buffer. The WTRU may select a plurality of bits for transmission from the interleaved bits.

A method, apparatus, and chipset are provided for constructing hybrid automatic repeat request (HARQ) rate-compatible polar codes for communication channels. The method includes constructing, in a terminal, a base polar code of length 2.sup.n; and determining a sequence of m<2.sup.n bits to puncture in the base polar code by testing a predetermined criterion at most (2.sup.2n+2.sup.n)/2−1 times.

.[.A method for constructing a low-density parity-check (LDPC) code using a structured base parity check matrix with permutation matrix, pseudo-permutation matrix, or zero matrix as constituent sub-matrices; and expanding the structured base parity check matrix into an expanded parity check matrix. A method for constructing a LDPC code using a structured base parity check matrix H=[H.sub.d|H.sub.p], H.sub.d is the data portion, and H.sub.p is the parity portion of the parity check matrix; the parity portion of the structured base parity check matrix is such so that when expanded, an inverse of the parity portion of the expanded parity check matrix is sparse; and expanding the structured base parity check matrix into an expanded parity check matrix. A method for encoding variable sized data by using the expanded LDPC code; and applying shortening, puncturing..]. .Iadd.System and method for operating a wireless device to encode data using low-density parity-check (LDPC) encoding is discussed. One example method includes: computing a number of modulated orthogonal frequency-division multiplexing (OFDM) symbols for transmitting the data; computing a number of shortening bits; distributing the number of shortening bits over the at least one LDPC codeword; computing a number of puncturing bits for the at least one LDPC codeword; distributing the number of puncturing bits over the at least one LDPC codeword; determining a criterion using at least one of the number of shortening bits and the number of puncturing bits; if the criterion is met, increasing the number of modulated OFDM symbols and recalculating the number of puncturing bits; generating the encoded data using the number of shortening bits, the number of puncturing bits, and the at least one LDPC codeword; and transmitting the encoded data..Iaddend.

Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to methods and apparatus for rate-matching a stream of bits encoded using polar codes. An exemplary method generally includes encoding K information bits using a polar code with a mother code length, N, to generate a stream of encoded bits storing a portion of the encoded bits in a circular buffer of size N reordering P blocks of the circular buffer according to row weights of a Hadamard matrix J interlacing the encoded bits of the blocks having a same row weight selecting, based on the row weights, a subset of the encoded bits in the blocks to modify modifying the selected subset of the encoded bits and transmitting the encoded bits in the P blocks, subsequent to modifying the selected subset of the encoded bits, via transmission resources.