Patent Description:
Channel coding is usually used in a communications system to improve data transmission reliability, so as to ensure communication quality. Polar codes (Polar codes) proposed by Turkish professor Arikan are the first desirable codes that have been theoretically proved to be able to achieve a Shannon capacity and that have low encoding and decoding complexity. A polar code is a linear block code, and its encoding matrix is GN. For example, a polar encoding process is indicated as <MAT>, where <MAT> is a binary row vector, a length of <MAT> is N (that is, a mother code length); GN is an N×N matrix, and <MAT> is defined as a Kronecker (Kronecker) product of log<NUM> N matrices F<NUM>.

In a polar encoding process, some bits in <MAT> are used to carry information and are referred to as information bits, and a set of indexes of these bits is denoted as <IMG>; and the other bits in <MAT> are set to fixed values that are pre-agreed on by a receive end and a transmit end and are referred to as fixed bits or frozen bits (frozen bits), and a set of indexes of these bits is denoted as a complementary set <IMG> of <IMG>. The polar encoding process is equivalently indicated as <MAT>. Herein, GN(A) is a sub-matrix formed by rows, corresponding to the indexes in the set A, in GN, and GN(AC) is a sub-matrix formed by rows, corresponding to the indexes in the set AC, in GN. uA is a set of the information bits in <MAT>, a quantity of the information bits is K, uAc is a set of the fixed bits in <MAT>, a quantity of the fixed bits is (N-K), and the fixed bits are known bits. These fixed bits are usually set to <NUM>, but a fixed bit may be set randomly provided that the receive end and the transmit end have a pre-agreement. When the fixed bits are set to <NUM>, an encoding output of the polar code may be simplified as <MAT>, where GN(A) is a K × N matrix.

A construction process of the polar code is a selection process of the set A , and determines polar code performance. The construction process of the polar code usually includes: determining, based on a mother code length N, that there are a total of N polarized channels that are respectively corresponding to N rows of the encoding matrix; calculating reliability of the polarized channels; and using indexes of the first K polarized channels with higher reliability as elements of the set A, and using indexes of the rest (N-K) polarized channels as elements of the index set Ac of the fixed bits. The set A determines positions of the information bits, and the set Ac determines positions of the fixed bits.

It may be seen from the encoding matrix that, a code length of an original polar code (mother code) is an integral power of <NUM>. In actual application, rate matching usually needs to be performed to obtain a polar code with any code length, and a puncturing (puncture) manner may usually be used to implement rate matching.

In the prior art, conventional random puncturing may be used, that is, a position in which puncturing needs to be performed is randomly determined. For example, a mother code length of a polar code is <NUM>, a quantity of positions in which puncturing needs to be performed is <NUM>. In this case, six puncturing positions are selected randomly from <NUM> positions. Implementing rate matching in the random puncturing manner reduces polar code performance. More information can be found in <NPL>. In this document a simplified polar code construction and rate-matching scheme are discussed. Further information is available in the document <NPL>. In this document a design of rate-compatible polar codes suitable for HARQ communications is proposed. The proposed design comprises a feature wherein the puncturing order is chosen with low complexity on a base code of short length, which is then further polarized to the desired length. With the document a practical ratematching system that has the flexibility to choose any desired rate through puncturing or repetition while preserving the polarization is suggested as well. The proposed rate-matching system is combined with channel interleaving and a bit-mapping procedure that preserves the polarization of the rate-compatible polar code family over bit-interleaved coded modulation systems. A further document, providing more information is <NPL>. Therein, a bit reversal permutation and its application are discussed. The document <NPL> can be considered as another source of information. Therein, the construction and the the rate matching of polar codes are discussed and an ordered sequence design for polar codes is proposed.

Embodiments of this application provide a polar code rate matching method and apparatus, so as to improve polar code performance. Embodiments and aspects described in conjunction with <FIG>, <FIG> and <FIG> are presented not as embodiments of the invention but as examples useful for understanding the invention.

According to a first aspect, a polar code rate matching method for a communication system applying polar mother codes and supporting target code lengths including a maximum target code length corresponding to a maximum polar mother code length Nmax is provided, including:
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 puncturing on the N encoded bits based on the first puncturing sequence to implement rate matching.

The determining N to-be-encoded bits includes: determining N based on M, where <MAT>, the symbol <IMG> represents a rounding-down operation, M is an output target code length of a polar code, M is not equal to a positive integer power of <NUM>, M is a positive integer, and the quantity of to-be-punctured bits is Q=N-M.

The 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 includes:
obtaining a third puncturing sequence corresponding to the information bit length N1 and a maximum mother code length, where the maximum mother code length is a mother code length corresponding to the maximum target code length supported by a communications system to which the polar code is applied; and determining the first puncturing sequence from the third puncturing sequence based on the quantity N of the encoded bits and the quantity Q of to-be-punctured bits.

In a possible implementation, the obtaining a third puncturing sequence corresponding to the information bit length N1 and a maximum mother code length includes:
obtaining the third puncturing sequence from a puncturing sequence in an appendix table <NUM> or an equivalent replacement sequence of the puncturing sequence in the table <NUM>.

In a possible implementation, the determining the first puncturing sequence from the third puncturing sequence based on the quantity N of the encoded bits and the quantity Q of to-be-punctured bits includes:
successively reading, starting from the first to-be-punctured bit in the third puncturing sequence, to-be-punctured bits that are not greater than N; and when a quantity of read to-be-punctured bits reaches the quantity Q of to-be-punctured bits, determining a sequence including the read Q to-be-punctured bits as the first puncturing sequence.

According to a second aspect, a polar code rate matching apparatus for a communication system applying polar mother codes and supporting target code lengths including a maximum target code length corresponding to a maximum polar mother code length Nmax is provided, including:
a determining module, configured to determine N to-be-encoded bits, where the N to-be-encoded bits include N1 information bits, and both N1 and N are positive integers; an encoding module, configured to encode the N to-be-encoded bits to obtain N encoded bits; a first-puncturing-sequence obtaining module, configured to obtain 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 a puncturing module, configured to perform puncturing on the N encoded bits based on the first puncturing sequence to implement rate matching.

The determining module is specifically configured to:
determine N based on M, where <MAT>, the symbol └┘ represents a rounding-down operation, M is an output target code length of a polar code, M is not equal to a positive integer power of <NUM>, M is a positive integer, and the quantity of to-be-punctured bits is Q=N-M.

The first-puncturing-sequence obtaining module includes:
a third-puncturing-sequence obtaining module, configured to obtain a third puncturing sequence corresponding to the information bit length N1 and the maximum mother code length, where the maximum mother code length is a mother code length corresponding to a maximum target code length supported by a communications system to which the polar code is applied; and a first-puncturing-sequence determining module, configured to determine the first puncturing sequence from the third puncturing sequence based on the quantity N of the encoded bits and the quantity Q of to-be-punctured bits.

In a possible implementation, the third-puncturing-sequence obtaining module is specifically configured to:
obtain the third puncturing sequence from a puncturing sequence in an appendix table <NUM> or an equivalent replacement sequence of the puncturing sequence in the table <NUM>.

In a possible implementation, the first-puncturing-sequence determining module is specifically configured to:
successively read, starting from the first to-be-punctured bit in the third puncturing sequence, to-be-punctured bits that are not greater than N; and when a quantity of read to-be-punctured bits reaches the quantity Q of to-be-punctured bits, determine a sequence including the read Q to-be-punctured bits as the first puncturing sequence.

According to a third aspect, a communications apparatus is provided, including:.

Another aspect of this application provides a computer-readable storage medium, where the computer-readable storage medium stores an instruction, and when the instruction runs on a computer, the computer is enabled to perform the method in the foregoing aspects.

Another aspect of this application provides a computer program product including an instruction, where when the instruction runs on a computer, the computer is enabled to perform the method in the foregoing aspects.

Another aspect of this application provides a computer program, where when the computer program runs on a computer, the computer is enabled to perform the method in the foregoing aspects.

In the embodiments of this application, the 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 to-be-punctured bits, and are not generated randomly. Therefore, a polar code performance can be improved.

The embodiments of this application may be applied to various communications systems, and therefore the following description is not limited to a specific communications system. A global system for mobile communications (Global System of Mobile communication, "GSM" for short) system, a code division multiple access (Code Division Multiple Access, "CDMA" for short) system, a wideband code division multiple access (Wideband Code Division Multiple Access, "WCDMA" for short) system, a general packet radio service (General Packet Radio Service, "GPRS" for short) system, a long term evolution (Long Term Evolution, "LTE" for short) system, an LTE frequency division duplex (Frequency Division Duplex, "FDD" for short) system, an LTE time division duplex (Time Division Duplex, "TDD" for short) system, a universal mobile telecommunications system (Universal Mobile Telecommunications System, "UMTS" for short), or the like. Polar coding in the embodiments can be used for all information or data that can be processed through conventional turbo coding or LDPC coding by a base station or a terminal in the foregoing system.

Terms such as "component", "module", and "system" used in this specification are used to indicate computer-related entities, hardware, firmware, combinations of hardware and software, software, or software being executed. For example, a component may be, but is not limited to, a process that runs on a processor, a processor, an object, an executable file, a thread of execution, a program, and/or a computer. As shown in figures, both an application that runs on a computing device and a computing device may be components. One or more components may reside within a process and/or a thread of execution, and a component may be located on one computer and/or distributed between two or more computers. In addition, these components may be executed from various computer-readable media that store various data structures. The components may perform communication by using a local and/or remote process and based on, for example, a signal having one or more data packets (for example, data from two components interacting with another component in a local system, a distributed system, and/or across a network such as the Internet interacting with other systems by using the signal).

In addition, the embodiments are described with reference to an access terminal. The access terminal may also be referred to as a system, a subscriber unit, a subscriber station, a mobile station, a mobile console, a remote station, a remote terminal, a mobile device, a user terminal, a terminal, a wireless communications device, a user agent, a user apparatus, or UE (User Equipment, user equipment). The access terminal may be a cellular phone, a cordless phone, a SIP (Session Initiation Protocol, session initiation protocol) phone, a WLL (Wireless Local Loop, wireless local loop) station, a PDA (Personal Digital Assistant, personal digital assistant), a handheld device with a wireless communication function, a computing device, or another processing device connected to a wireless modem. In addition, the embodiments are described with reference to a base station. The base station can be used for communicating with a mobile device, and the base station may be a BTS (Base Transceiver Station, base transceiver station) in a GSM (Global System of Mobile Communication, global system for mobile communications) system or in a CDMA (Code Division Multiple Access, code division multiple access) system; or may be an NB (NodeB, NodeB) in a WCDMA (Wideband Code Division Multiple Access, wideband code division multiple access) system; or may be an eNB or eNodeB (Evolved Node B, evolved NodeB) in an LTE (Long Term Evolution, long term evolution) system, a relay station, an access point, a base station device in a future <NUM> network, or the like.

<FIG> shows a wireless communications system <NUM> according to the embodiments described in this specification. The system <NUM> includes a base station <NUM>, and the base station <NUM> may include a plurality of antenna groups. For example, one antenna group may include antennas <NUM> and <NUM>, another antenna group may include antennas <NUM> and <NUM>, and an additional group may include antennas <NUM> and <NUM>. For each antenna group, two antennas are shown. However, more or less antennas may be used in each group. The base station <NUM> may additionally include a transmitter chain and a receiver chain. A person of ordinary skill in the art may understand that both the transmitter chain and the receiver chain may include a plurality of components related to signal transmission and reception (for example, a processor, a modulator, a multiplexer, a demodulator, a demultiplexer, or an antenna).

The base station <NUM> may communicate with one or more access terminals (for example, an access terminal <NUM> and an access terminal <NUM>). However, it may be understood that the base station <NUM> may communicate with basically any quantity of access terminals similar to the access terminals <NUM> and <NUM>. The access terminals <NUM> and <NUM> may be, for example, cellular phones, smartphones, portable computers, handheld communications devices, handheld computing devices, satellite radio apparatuses, global positioning systems, PDAs, and/or any other appropriate devices that are configured to perform communication in the wireless communications system <NUM>. As shown in the figure, the access terminal <NUM> communicates with the antennas <NUM> and <NUM>. The antennas <NUM> and <NUM> send information to the access terminal <NUM> through a forward link <NUM>, and receive information from the access terminal <NUM> through a reverse link <NUM>. In addition, the access terminal <NUM> communicates with the antennas <NUM> and <NUM>. The antennas <NUM> and <NUM> send information to the access terminal <NUM> through a forward link <NUM>, and receive information from the access terminal <NUM> through a reverse link <NUM>. For example, in an FDD (Frequency Division Duplex, frequency division duplex) system, for example, a frequency band used for the forward link <NUM> may be different from that used on the reverse link <NUM>, and a frequency band used for the forward link <NUM> may be different from that used on the reverse link <NUM>. In addition, in a TDD (Time Division Duplex, time division duplex) system, a frequency band used for the forward link <NUM> may be the same as that used on the reverse link <NUM>, and a frequency band used for the forward link <NUM> may be the same as that used on the reverse link <NUM>.

Each antenna group and/or area designed for communication are/is referred to as a sector of the base station <NUM>. For example, an antenna group may be designed to communicate with an access terminal in a sector of a coverage area of the base station <NUM>. During communication through the forward links <NUM> and <NUM>, transmit antennas of the base station <NUM> may increase signal-to-noise ratios of the forward links <NUM> and <NUM> for the access terminals <NUM> and <NUM> through beamforming. In addition, compared with a manner in which a base station uses a single antenna to send information to all access terminals served by the base station, when the base station <NUM> sends, through beamforming, information to the access terminals <NUM> and <NUM> that are distributed randomly in the related coverage area, a mobile device in a neighboring cell receives less interference.

Within a given time, the base station <NUM>, the access terminal <NUM>, and/or the access terminal <NUM> may be a wireless communications sending apparatus and/or a wireless communications receiving apparatus. When sending data, the wireless communications sending apparatus may encode the data for transmission. Specifically, the wireless communications sending apparatus may have (for example, generate, obtain, or store in a memory), a specific quantity of information bits to be sent to the wireless communications receiving apparatus through a channel. Such information bits may be included in a data transport block (or a plurality of transport blocks), and the transport block may be segmented to generate a plurality of code blocks. In addition, the wireless communications sending apparatus may use a polar code encoder (which is not shown) to encode each code block.

<FIG> shows a basic flowchart of wireless communication. At a transmit end, a signal source is sent after having successively undergone source encoding, channel encoding, and digital modulation. At a receive end, after having successively undergone digital demodulation, channel decoding, and source decoding, a processed signal source is output to a sink. A polar code may be used for channel encoding and decoding. Because a code length of an original polar code (mother code) is an integral power of <NUM>, in actual application, rate matching needs to be performed to obtain a polar code with any code length. As shown in <FIG>, at the transmit end, rate matching is performed after channel encoding to obtain any target code length; and at the receive end, rate de-matching is performed before channel decoding.

<FIG> is a schematic diagram of a polar encoding and rate matching process according to an embodiment of this application. It can be seen from <FIG> that, polar encoding and rate matching mainly includes four processing processes: construction, encoding, puncturing sequence determining, and rate matching.

Construction process: Input N1 information bits are received, and a mother code length N is determined, where the mother code length N is determined based on a target code length M obtained after rate matching, a quantity of to-be-encoded bits is N, the N to-be-encoded bits includes N1 information bits and N2 fixed bits, and one bit (an information bit or a fixed bit) corresponds to one polarized channel. Positions of the N1 information bits form an information bit position set, and positions of the N2 fixed bits form a fixed-bit position set. The information bit position set may be specifically a set of indexes of the information bits, and a manner of determining the information bit position set is not limited in this application. For example, a position of an information bit may be determined based on reliability of a polarized channel. Specifically, reliability of a polarized channel is estimated based on an actual parameter and a code rate of the polarized channel, and an information bit is set in a position corresponding to a polarized channel with high reliability, or a position of an information bit may be determined based on a polarization weight of a polarized channel.

Encoding process: Polar encoding is performed on the to-be-encoded bits to obtain encoded bits.

Puncturing sequence determining: A puncturing sequence is determined, where the puncturing sequence is a set of to-be-punctured bits and is used to indicate puncturing positions, and a quantity of elements included in the puncturing sequence is a quantity of to-be-punctured bits.

Rate matching: Puncturing is performed on the encoded bits based on the determined puncturing sequence to implement rate matching. Specifically, some encoded bits are selected from the encoded bits according to the determined puncturing sequence, and are directly discarded without being transmitted through a channel, so as to be adapted to the target code length to adjust an encoding code rate.

<FIG> shows a polar code rate matching method <NUM> according to an embodiment of this application. Specifically, the rate matching method <NUM> includes the following steps.

The N to-be-encoded bits include N1 information bits, and both N1 and N are positive integers.

Specifically, N is determined based on an output target code length M of a polar code, where <MAT>, the symbol <IMG> represents a rounding-down operation, M is not equal to a positive integer power of <NUM>, M is a positive integer, the N to-be-encoded bits correspond to N polarized channel, and one bit corresponds to one polarized channel.

A puncturing manner is used to implement rate matching, and a quantity of to-be-punctured bits is Q=N-M.

It should be noted that, in this embodiment of this application, the information bits may include only information bits, or may be bits with a specific function relationship with the information bits, or may include information bits and check bits, and the check bit may be a CRC bit or a parity check bit.

S320: Encode the N to-be-encoded bits to obtain N encoded bits.

Specifically, an encoding matrix FN of the polar code may be used to complete an encoding process of the to-be-encoded bits, so as to obtain the encoded bits after polar encoding.

S330: Obtain 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.

Specifically, the following provides three specific implementations with reference to <FIG>, <FIG>, where solely the embodiment according to <FIG> falls under the scope of the claimed invention and the examples according to <FIG> and <FIG> are solely for illustrative purpose.

The information bit length means a quantity of the information bits. When the information bits include an information bit and a check bit, the information bit length means a sum of a quantity of the information bits and a quantity of the check bits; and the quantity N of the encoded bits is a mother code length N.

S340: Perform puncturing on the N encoded bits based on the first puncturing sequence to implement rate matching.

Specifically, some encoded bits are selected from the encoded bits based on to-be-punctured bits indicated in the first puncturing sequence, and are directly discarded without being transmitted through a channel, so as to be adapted to the target code length to adjust an encoding code rate.

The following provides three specific implementations of S330 with reference to <FIG>, <FIG>.

As shown in <FIG>, S330 of 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 includes the following steps.

S331a: Obtain a second puncturing sequence corresponding to the information bit length N1 and the quantity N of the encoded bits, where a length of the second puncturing sequence is (N/<NUM>)-<NUM>.

Specifically, an appendix table <NUM> provides second puncturing sequences corresponding to different values of the information bit length N1 and different values of the quantity N of the encoded bits. For example, when the information bit length is N1=<NUM>, the quantity of the encoded bits (the mother code length) is N=<NUM>, the table <NUM> provides three possible second puncturing sequences. When the information bit length is N1=<NUM>, the quantity of the encoded bits (the mother code length) is N=<NUM>, the table <NUM> also provides three possible second puncturing sequences. It should be noted that, the information bit length N1 may also be equal to a replacement value of <NUM>, and the replacement value of <NUM> indicates that the information bit length N1 may be a value close to <NUM>. For example, the replacement value of <NUM> may be a value in an interval [<NUM>, <NUM>], or a value in an interval [<NUM>, <NUM>].

Therefore, the second puncturing sequence may be obtained through query of a puncturing sequence in the table <NUM> or an equivalent replacement sequence of the puncturing sequence in the table <NUM>. An element in the puncturing sequence in the table <NUM> is used to indicate a sequence number of a polarized channel, all or a part of the puncturing sequences in the table <NUM> may be stored in a communications system to which this implementation is applied.

It should be noted that, the table <NUM> and a table <NUM> in the following are only examples, and adjustment or equivalent replacement made to the puncturing sequences in the table <NUM> and the table <NUM> without affecting an overall effect of the table <NUM> and the table <NUM> may include but not be limited to the following several aspects.

S332a: Determine the first puncturing sequence from the second puncturing sequence based on the quantity Q of to-be-punctured bits.

Specifically, Q to-be-punctured bits are selected from the second puncturing sequence as the first puncturing sequence. For example, a sequence including the first Q to-be-punctured bits in the second puncturing sequence is determined as the first puncturing sequence, or a sequence including the last Q to-be-punctured bits in the second puncturing sequence is determined as the first puncturing sequence. How to select Q to-be-punctured bits from the second puncturing sequence as the first puncturing sequence is not specifically limited in this embodiment.

It can be learned from the embodiment corresponding to <FIG> that, computing complexity during construction of the first puncturing sequence can be reduced through storage of the second puncturing sequences in the communications system.

As shown in <FIG>, in an embodiment of this application, S330 of 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 includes the following steps.

S331b: Obtain a third puncturing sequence corresponding to the information bit length N1 and a maximum mother code length Nmax.

The maximum mother code length Nmax is a mother code length corresponding to a maximum target code length supported by the communications system to which the polar code is applied, a length of the third puncturing sequence is Nmax-<NUM>, and the third puncturing sequence is a maximum puncturing sequence corresponding to the maximum mother code length Nmax.

Specifically, the appendix table <NUM> provides third puncturing sequences corresponding to different values of the information bit length N1 and different values of the maximum mother code length Nmax. For example, when the information bit length is N1=<NUM>, the maximum mother code length is Nmax=<NUM>, the table <NUM> provides three possible third puncturing sequences. It should be noted that, the information bit length N1 may be equal to a replacement value of <NUM>, and the replacement value of <NUM> indicates that the information bit length N1 may be a value close to <NUM>. For example, the replacement value of <NUM> may be a value in an interval [<NUM>, <NUM>], or a value in an interval [<NUM>, <NUM>].

Therefore, the third puncturing sequence may be obtained through query of a puncturing sequence in the table <NUM> or an equivalent replacement sequence of the puncturing sequence in the table <NUM>. An element in the puncturing sequence in the table <NUM> is used to indicate a sequence number of a polarized channel, all or a part of the puncturing sequences in the table <NUM> may be stored in the communications system to which this implementation is applied.

That the puncturing sequence in the table <NUM> can be used for equivalent replacement is described above, and details are not described herein again.

S332b: Determine the first puncturing sequence from the third puncturing sequence based on the quantity N of the encoded bits and the quantity Q of to-be-punctured bits.

Specifically, to-be-punctured bits that are not greater than N are successively read starting from the first to-be-punctured bit in the third puncturing sequence; and when a quantity of read to-be-punctured bits reaches the quantity Q of to-be-punctured bits, a sequence including the read Q to-be-punctured bits is determined as the first puncturing sequence.

Obviously, alternatively, to-be-punctured bits that are not greater than N may be successively read starting from the last to-be-punctured bit in the third puncturing sequence. Reading is performed starting from which element in the third puncturing sequence is not limited in this embodiment.

It can be learned from the embodiment corresponding to <FIG> that, computing complexity during construction of the first puncturing sequence can be reduced through storage of the third puncturing sequences in the communications system.

S331c: Determine the first to-be-punctured bit from the N encoded bits based on the N1 information bits.

Specifically, when each bit in the N encoded bits is used as a to-be-punctured bit, an error probability of polarized channels corresponding to the N1 information bits is separately calculated; and a minimum error probability is determined from the calculated N error probabilities, and an encoded bit corresponding to the minimum error probability is determined as the first to-be-punctured bit.

The calculating an error probability of polarized channels corresponding to the N1 information bits includes:
adding up error probabilities of the polarized channels corresponding to all of the N1 information bits to obtain the error probability of the polarized channels corresponding to the N1 information bits.

It should be noted that, the error probability of polarized channels corresponding to the information bits can be calculated by using a method such as a density evolution method or a Gaussian approximation method. How to calculate the error probability of the polarized channels is not specifically limited in this embodiment.

S332c: Separately determine, by traversing i values from <NUM> to the quantity Q of to-be-punctured bits, the ith to-be-punctured bit from (N-i+<NUM>) encoded bits remaining after determined (i-<NUM>) to-be-punctured bits are excluded from the N encoded bits, where <NUM>≤i≤Q.

Specifically, the determining the ith to-be-punctured bit from (N-i+<NUM>) encoded bits remaining after determined (i-<NUM>) to-be-punctured bits are excluded from the N encoded bits includes:
when each of the (N-i+<NUM>) encoded bits is used as a to-be-punctured bit, separately calculating an error probability of polarized channels corresponding to the N1 information bits; and determining a minimum error probability from the calculated (N-i+<NUM>) error probabilities, and determining an encoded bit corresponding to the minimum error probability as the ith to-be-punctured bit.

For example, when i=<NUM>, it indicates that a second round of determining a puncturing position is performed. In this case, determining the second puncturing position from positions of (N-<NUM>) encoded bits remaining after one puncturing position is excluded from positions of the N encoded bits includes:
when each of the (N-<NUM>) encoded bits is used as a to-be-punctured bit, calculating an error probability of polarized channels corresponding to the N1 information bits; and determining a minimum error probability from the calculated (N-<NUM>) error probabilities, and determining an encoded bit corresponding to the minimum error probability as the second to-be-punctured bit.

S333c: Use a sequence including the determined Q to-be-punctured bits as the first puncturing sequence.

It can be learned from the example not falling under the scope of the claimed invention corresponding to <FIG>, the first puncturing sequence is determined through online calculation with no needs to store a puncturing sequence in the communications system, so as to save a storage resource.

In the rate matching method provided in this application, the 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 to-be-punctured bits, and are not generated randomly. Therefore, polar code performance can be improved.

With reference to <FIG>, the following describes a polar code rate matching apparatus <NUM> provided in an embodiment of this application. The rate matching apparatus <NUM> includes a determining module <NUM>, an encoding module <NUM>, a first-puncturing-sequence obtaining module <NUM>, and a puncturing module <NUM>.

The determining module <NUM> is configured to determine N to-be-encoded bits, where the N to-be-encoded bits include N1 information bits, and both N1 and N are positive integers.

Specifically, the determining module <NUM> is configured to determine N based on M, where <MAT>, the symbol <IMG> represents a rounding-down operation, M is an output target code length of a polar code, M is not equal to a positive integer power of <NUM>, M is a positive integer, and a quantity of to-be-punctured bits is Q=N-M.

The encoding module <NUM> is configured to encode the N to-be-encoded bits to obtain N encoded bits.

The first-puncturing-sequence obtaining module <NUM> is configured to obtain a first puncturing sequence based on an information bit length N1, the quantity N of the encoded bits, and the quantity Q of to-be-punctured bits.

The puncturing module <NUM> is configured to perform puncturing on the N encoded bits based on the first puncturing sequence to implement rate matching.

In an example not falling under the scope of the claimed invention, as shown in <FIG>, the first-puncturing-sequence obtaining module <NUM> includes a second-puncturing-sequence obtaining module <NUM> and a first-puncturing-sequence determining module <NUM>.

The second-puncturing-sequence obtaining module <NUM> is configured to obtain a second puncturing sequence corresponding to the information bit length N1 and the quantity N of the encoded bits, where a length of the second puncturing sequence is (N/<NUM>)-<NUM>.

The first-puncturing-sequence determining module <NUM> is configured to determine the first puncturing sequence from the second puncturing sequence based on the quantity Q of to-be-punctured bits.

Specifically, the second-puncturing-sequence obtaining module <NUM> may obtain the second puncturing sequence from a puncturing sequence in an appendix table <NUM> or an equivalent replacement sequence of the puncturing sequence in the table <NUM>; and the first-puncturing-sequence determining module <NUM> may determine a sequence including the first Q to-be-punctured bits in the second puncturing sequence, as the first puncturing sequence.

In an embodiment of this application, as shown in <FIG>, the first-puncturing-sequence obtaining module <NUM> includes a third-puncturing-sequence obtaining module <NUM> and the first-puncturing-sequence determining module <NUM>.

The third-puncturing-sequence obtaining module <NUM> is configured to obtain a third puncturing sequence corresponding to the information bit length N1 and a maximum mother code length, where the maximum mother code length is a mother code length corresponding to a maximum target code length supported by a communications system to which the polar code is applied.

The first-puncturing-sequence determining module <NUM> is configured to determine the first puncturing sequence from the third puncturing sequence based on the quantity N of the encoded bits and the quantity Q of to-be punctured bits.

Specifically, the third-puncturing-sequence obtaining module <NUM> may obtain the third puncturing sequence from a puncturing sequence in an appendix table <NUM> or an equivalent replacement sequence of the puncturing sequence in the table <NUM>; and the first-puncturing-sequence determining module <NUM> is specifically configured to: successively read, starting from the first to-be-punctured bit in the third puncturing sequence, to-be-punctured bits that are not greater than N; and when a quantity of read to-be-punctured bits reaches the quantity Q of to-be-punctured bits, determine a sequence including the read Q to-be-punctured bits as the first puncturing sequence.

In an example not falling under the scope of the claimed invention, the first-puncturing-sequence obtaining module <NUM> is specifically configured to: determine the first to-be-punctured bit from the N encoded bits based on the N1 information bits; separately determine, by traversing i values from <NUM> to the quantity Q of to-be-punctured bits, the ith to-be-punctured bit from (N-i+<NUM>) encoded bits remaining after determined (i-<NUM>) to-be-punctured bits are excluded from the N encoded bits, where <NUM>≤i≤Q; and use a sequence including the determined Q to-be-punctured bits as the first puncturing sequence.

The determining the first to-be-punctured bit from the N encoded bits based on the N1 information bits includes: when each of the N encoded bits is used as a to-be-punctured bit, separately calculating an error probability of polarized channels corresponding to the N1 information bits; and determining a minimum error probability from the calculated N error probabilities, and determining an encoded bit corresponding to the minimum error probability as the first to-be-punctured bit.

The determining the ith to-be-punctured bit from (N-i+<NUM>) encoded bits remaining after determined (i-<NUM>) to-be-punctured bits are excluded from the N encoded bits includes: when each of the (N-i+<NUM>) encoded bits is used as a to-be-punctured bit, separately calculating an error probability of polarized channels corresponding to the N1 information bits; and determining a minimum error probability from the calculated (N-i+<NUM>) error probabilities, and determining an encoded bit corresponding to the minimum error probability as the ith to-be-punctured bit.

Further, the calculating an error probability of polarized channels corresponding to the N1 information bits includes: adding up error probabilities of the polarized channels corresponding to all of the N1 information bits to obtain the error probability of the polarized channels corresponding to the N1 information bits.

In the rate matching apparatus provided in this embodiment of this application, the 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 to-be-punctured bits, and are not generated randomly. Therefore, a polar code performance can be improved.

<FIG> is a schematic structural diagram of a communications apparatus <NUM> according to an embodiment of this application (for example, a communications apparatus such as an access point, a base station, a station, or a terminal; or a chip in the foregoing communications apparatus).

As shown in <FIG>, the communications apparatus <NUM> may be implemented by using a bus <NUM> as a general bus architecture. Based on a specific application and an overall design constraint of the communications apparatus <NUM>, the bus <NUM> may include any quantity of interconnection buses and bridges. The bus <NUM> connects various circuits together, and the circuits include a processor <NUM>, a storage medium <NUM>, and a bus interface <NUM>. Optionally, the communications apparatus <NUM> uses the bus interface <NUM> to connect a network adapter <NUM> and the like through the bus <NUM>. The network adapter <NUM> may be configured to implement a signal processing function of a physical layer in a wireless communications network, and implement sending and receiving of a radio frequency signal through an antenna <NUM>. A user interface <NUM> may be connected to a user terminal such as a keyboard, a display, a mouse, or a joystick. The bus <NUM> may be further connected to various other circuits, such as a timing source, a peripheral device, a voltage regulator, or a power management circuit. The circuits are well known in the art, and therefore details are not described herein.

Alternatively, the communications apparatus <NUM> may be configured as a general-purpose processing system. For example, the general-purpose processing system may be generally referred to as a chip. The general-purpose processing system includes one or more microprocessors providing a processor function, and an external memory providing at least one part of the storage medium <NUM>; and all these are connected to another support circuit through an external bus architecture.

Alternatively, the communications apparatus <NUM> may be implemented through the following: an ASIC (application-specific integrated circuit) with the processor <NUM>, the bus interface <NUM>, and the user interface <NUM> and at least one part of the storage medium <NUM> integrated into a single chip; or the communications apparatus <NUM> may be implemented through the following: one or more FPGAs (field-programmable gate array), a PLD (programmable logic device), a controller, a state machine, gate logic, a discrete hardware component, any other suitable circuit, or any combination of circuits implementing various functions described in this application.

The processor <NUM> is responsible for bus management and general processing (including executing software stored in the storage medium <NUM>). The processor <NUM> may be implemented through one or more general-purpose processors and/or one or more special-purpose processors. For example, the processor includes a microprocessor, a microcontroller, a DSP processor, and another circuit that can execute software. The software should be broadly explained as indicating an instruction, data, or any combination thereof, regardless of that it is referred as software, firmware, middleware, microcode, hardware description language, and the like.

As shown in the following figure, the storage medium <NUM> is separated from the processor <NUM>. However, a person skilled in the art easily understands that, the storage medium <NUM> and any part thereof may be located outside the communications apparatus <NUM>. For example, the storage medium <NUM> may include a transmission line, a carrier waveform modulated by using data, and/or a computer product separated from a wireless node, and all the media may be accessed by the processor <NUM> through the bus interface <NUM>. Alternatively, the storage medium <NUM> and any part thereof may be integrated into the processor <NUM>. For example, the storage medium <NUM> may be a cache and/or a general register.

The processor <NUM> may implement the foregoing embodiments, for example, the embodiments successively corresponding to <FIG>, <FIG>, and an implementation process of the processor <NUM> is not described herein.

The communications apparatus described in the embodiments of this application may be a wireless communications device such as an access point, a station, a base station, or a user terminal.

The polar code described in the embodiments of this application includes but is not limited to an Arikan polar code, or may be a CA-polar code or a PC-polar code. The Arikan polar code is an original polar code, is not concatenated with other code, and includes only an information bit and a frozen bit. The CA-polar code is a polar code obtained by concatenating a polar code with a cyclic redundancy check (Cyclic Redundancy Check, CRC for short) code, and the PC-polar code is a code obtained by concatenating a polar code with a parity check (Parity Check, PC for short) code. The PC-polar code and the CA-polar code improve polar code performance through concatenating different codes.

The fixed bits described in the embodiments of this application may also be referred to as frozen bits. In the examples described in the embodiments of this application, units and method processes may be implemented by electronic hardware or a combination of computer software and electronic hardware. A person skilled in the art can implement the described functions by using different methods for each specific application.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other manners. For example, the described apparatus embodiments are merely examples. For example, the module division is merely logical function division and may be other division in actual implementation. For example, a plurality of modules or units may be combined or integrated into another system, or some steps may be ignored or not performed. In addition, coupling, direct coupling, or a communication connection between the modules or units may be implemented through some interfaces, and these may be in an electrical form, a mechanical form, or another form.

The unit described as a separate component may be or not be separate physically, and may be disposed in one position, or may be distributed to a plurality of network units.

All or some of the foregoing embodiments may be implemented through software, hardware, firmware, or any combination thereof. When software is used to implement the embodiments, the embodiments may be implemented completely or partially in a form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the procedure or functions according to the embodiments of this application are all or partially generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or another programmable apparatus. The computer instructions may be stored in a computer-readable storage medium or may be transmitted from a computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired (for example, a coaxial cable, an optical fiber, or a digital subscriber line (DSL)) or wireless (for example, infrared, radio, and microwave) manner. The computer-readable storage medium may be any usable medium accessible by a computer, or a data storage device, such as a server or a data center integrating one or more usable media. The usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, or a magnetic tape), an optical medium (for example, a DVD), a semiconductor medium (for example, Solid State Disk (SSD)), or the like.

Claim 1:
A polar code rate matching method for a communication system applying polar mother codes and supporting target code lengths including a maximum target code length corresponding to a maximum polar mother code length Nmax, the method comprising:
determining (S310) a polar mother code length N based on an output target code length M according to <MAT>, the symbol └┘ represents a rounding-down operation, M is not equal to a positive integer power of <NUM>, wherein a quantity of to-be-encoded bits is N, wherein the N to-be-encoded bits comprise N1 information bits, and both N1 and N are positive integers;
encoding (S320) the N to-be-encoded bits using a polar mother code with the determined polar mother code length N to obtain N encoded bits;
obtaining (S330) 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 is N-M; and
performing (S340) puncturing on the N encoded bits based on the first puncturing sequence to implement rate matching; and
wherein the obtaining (S330) 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 comprises:
obtaining (S331b) a third puncturing sequence corresponding to the information bit length N1 and the maximum mother code length Nmax;
wherein a length of the third puncturing sequence is Nmax-<NUM>, and the third puncturing sequence is a maximum puncturing sequence corresponding to the maximum mother code length Nmax;
wherein a plurality of third puncturing sequences corresponding to different values of the information bit length N1 and different values of the maximum mother code length Nmax are stored in the communication system;
wherein the third puncturing sequence is obtained through query a third puncturing sequence in said plurality of third puncturing sequences stored in the communication system; and
determining (S332b) the first puncturing sequence from the third puncturing sequence based on the quantity N of the encoded bits and the quantity Q of to-be-punctured bits.