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.

Systems and methods are disclosed herein for puncturing Polar-encoded bits. In some embodiments, a method of operation of a radio node that utilizes a Polar encoder comprising performing Polar encoding of a plurality of bits to provide a plurality of Polar-encoded code bits and puncturing the plurality of Polar-encoded code bits using a hybrid puncturing scheme to provide a plurality of rate-matched Polar-encoded code bits, wherein the hybrid puncturing scheme uses different puncturing patterns for different code rate regions.

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.

According to certain embodiments, a transmit node in a wireless communications system includes a first universal rate-compatible polar encoder and a transmitter. The first universal rate-compatible polar encoder is configured for a family of two or more types of channels and encodes a plurality of information bits to provide a plurality of coded bits. The transmitter transmits the plurality of coded bits to a receive node.

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.

An encoder for encoding K information bits into a code word of length N on the basis of a polar code of length N is provided, wherein N is a power of 2 and greater than or equal to N. The encoder comprises a memory storing a plurality of bit indices, which comprise a set of N frozen bit indices associated with the polar code of length N, a set of N/2 puncturing bit indices and/or a set of N/2 shortening bit indices and a processor configured to retrieve at least a subset of the plurality of bit indices from the memory, to encode the K information bits using the polar code of length N for obtaining encoded data of length N and to reduce the number of bits of the encoded data to the length N for obtaining the code word of length N.

Embodiments of this application provide a polar code rate matching method and apparatus, and a communications apparatus. The rate matching method includes: determining N to-be-encoded bits, where the N to-be-encoded bits include N1 information bits, and both N1 and N are positive integers; encoding the N to-be-encoded bits to obtain N encoded bits; obtaining a first puncturing sequence based on an information bit length N1, the quantity N of the encoded bits, and a quantity Q of to-be-punctured bits; and performing a puncturing operation on the N encoded bits based on the first puncturing sequence to implement a rate matching. To-be-punctured bits indicated in the first puncturing sequence are obtained based on the information bit length N1, the quantity N of the encoded bits, and the quantity Q of the to-be-punctured bits, and are not generated randomly.

Apparatus and methods are provided for polar code sub-block interleaving and bit selection. In one novel aspect, middle-part interlaced sub-block interleaving is provided for polar code interleaving. In one embodiment, the middle part of the polar code is interlaced and generates the interleaved polar code. In another embodiment, the lower part and the upper part are also sub-block interleaved with the middle-part interlaced method. In another novel, rate-dependent unified bit selection is provided. The bit selection is categorized into three operation categories of repetition, puncturing and the shortening. Each category follows unified bit selection rule with different categories differ only in the access scheme. In one embodiment, the circular buffer is used for bit selection.

Systems and methods are disclosed herein for puncturing Polar-encoded bits. In some embodiments, a method of operation of a radio node that utilizes a Polar encoder comprising performing Polar encoding of a plurality of bits to provide a plurality of Polar-encoded code bits and puncturing the plurality of Polar-encoded code bits using a hybrid puncturing scheme to provide a plurality of rate-matched Polar-encoded code bits, wherein the hybrid puncturing scheme uses different puncturing patterns for different code rate regions.