Patent Description:
Examples of such multiple-access technologies include Long Term Evolution (LTE) systems, code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC--FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

In some examples, a wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UEs). In LTE or LTE-A network, a set of one or more base stations may define an e NodeB (eNB). In other examples (e.g., in a next generation or <NUM> network), a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads (SRHs), transmission reception points (TRPs), etc.) in communication with a number of central units (CUs) (e.g., central nodes (CNs), access node controllers (ANCs), etc.), where a set of one or more distributed units, in communication with a central unit, may define an access node (e.g., a new radio base station (NR BS), a new radio node-B (NR NB), a network node, <NUM> NB, gNB, etc.). A base station or DU may communicate with a set of UEs on downlink channels (e.g., for transmissions from a base station or to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or distributed unit).

<NPL>, relates to Polar Code Rate-Matching Design. <NPL>, relates to Rate-Matching for Polar Codes.

After considering this discussion, and particularly after reading the section entitled "Detailed Description" one will understand how the features of this disclosure provide advantages that include improved communications in a wireless network.

So that the manner in which the features of the present invention as specified in the claims can be understood in detail, a more particular description, may be had by reference to aspects, some of which are illustrated in the appended drawings.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for multi-slice networks, such as new radio (NR) (new radio access technology or <NUM> technology).

NR may include Enhanced mobile broadband (eMBB) techniques targeting wide bandwidth (e.g. <NUM> and larger) communications, millimeter wave (mmW) techniques targeting high carrier frequency (e.g. <NUM>) communications, massive MTC (mMTC) techniques targeting non-backward compatible MTC techniques, and mission critical targeting ultra reliable low latency communications (URLLC).

Aspects of the present disclosure relate to a rate-matching scheme for control channels using polar codes. Rate matching is a process whereby the number of bits to be transmitted is matched to the available bandwidth of the number of bits allowed to be transmitted. In certain instances the amount of data to be transmitted is less than the available bandwidth, in which case all the data to be transmitted (and one or more copies of the data) will be transmitted (a technique called repetition). In other instances the amount of data to be transmitted exceeds the available bandwidth, in which case a certain portion of the data to be transmitted will be omitted from the transmission (a technique called puncturing).

In NR, polar codes may be used to encode a stream of bits for transmission. However, in some cases, using a traditional rate matching scheme (e.g., for TBCC codes) may lead to performance loss when used with polar codes. Thus, aspects of the present disclosure propose an efficient rate-matching scheme to be used to rate-match a stream of bits encoded using a polar code.

Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses, or objectives. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the figures and in the following description of the preferred aspects. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims.

The techniques described herein may be used for various wireless communication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. A CDMA network may implement a radio technology such as universal terrestrial radio access (UTRA), cdma2000, etc. UTRA includes wideband CDMA (WCDMA), time division synchronous CDMA (TD-SCDMA), and other variants of CDMA. A TDMA network may implement a radio technology such as global system for mobile communications (GSM). An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA), ultra mobile broadband (UMB), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, Flash-OFDM®, etc. UTRA and E-UTRA are part of universal mobile telecommunication system (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A), in both frequency division duplex (FDD) and time division duplex (TDD), are new releases of UMTS that use E-UTRA, which employs OFDMA on the downlink and SC-FDMA on the uplink. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies, such as a <NUM> next-en/NR network.

<FIG> illustrates an example wireless network <NUM>, such as a new radio (NR) or <NUM> network, in which aspects of the present disclosure may be performed, for example, for improving device discovery in a multi-slice network. In some cases, the network <NUM> may be a multi-slice network, each slice defines as a composition of adequately configured network functions, network applications, and underlying cloud infrastructures that are bundled together to meet the requirement of a specific use case or business model.

As illustrated in <FIG>, the wireless network <NUM> may include a number of BSs <NUM> and other network entities. A BS may be a station that communicates with UEs. Each BS <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a Node B and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term "cell" and eNB, Node B, <NUM> NB, AP, NR BS, NR BS, BS, or TRP may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile base station. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in the wireless network <NUM> through various types of backhaul interfaces such as a direct physical connection, a virtual network, or the like using any suitable transport network.

In some cases, NR or <NUM> RAT networks may be deployed, employing a multi-slice network architecture.

The BSs <NUM> may also communicate with one another, e.g., directly or indirectly via wireless or wireline backhaul.

A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE), a cellular phone, a smart phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainment device (e.g., a music device, a video device, a satellite radio, etc.), a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered evolved or machine-type communication (MTC) devices or evolved MTC (eMTC) devices. Some UEs may be considered Internet-of-Things (IoT) devices.

For example, the spacing of the subcarriers may be <NUM> and the minimum resource allocation (called a 'resource block') may be <NUM> subcarriers (or <NUM>). Consequently, the nominal FFT size may be equal to <NUM>, <NUM>, <NUM>, <NUM> or <NUM> for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM> megahertz (MHz), respectively. For example, a subband may cover <NUM> (i.e., <NUM> resource blocks), and there may be <NUM>, <NUM>, <NUM>, <NUM> or <NUM> subbands for system bandwidth of <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, respectively.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communications systems, such as NR/<NUM>.

A single component carrier bandwidth of <NUM> may be supported. NR resource blocks may span <NUM> sub-carriers with a subcarrier bandwidth of <NUM> over a <NUM> duration. Each radio frame may consist of <NUM> subframes with a length of <NUM>. Consequently, each subframe may have a length of <NUM>. Each subframe may indicate a link direction (i.e., DL or UL) for data transmission and the link direction for each subframe may be dynamically switched. Each subframe may include DL/UL data as well as DL/UL control data. UL and DL subframes for NR may be as described in more detail below with reference to <FIG>. Alternatively, NR may support a different air interface, other than an OFDM-based. NR networks may include entities such CUs and/or DUs.

As noted above, a RAN may include a CU and DUs. A NR BS (e.g., gNB, <NUM> Node B, Node B, transmission reception point (TRP), access point (AP)) may correspond to one or multiple BSs. NR cells can be configured as access cell (ACells) or data only cells (DCells). For example, the RAN (e.g., a central unit or distributed unit) can configure the cells. DCells may be cells used for carrier aggregation or dual connectivity, but not used for initial access, cell selection/reselection, or handover. In some cases DCells may not transmit synchronization signals-in some case cases DCells may transmit SS. NR BSs may transmit downlink signals to UEs indicating the cell type. Based on the cell type indication, the UE may communicate with the NR BS. For example, the UE may determine NR BSs to consider for cell selection, access, handover, and/or measurement based on the indicated cell type.

<FIG> illustrates example components of the BS <NUM> and UE <NUM> illustrated in <FIG>, which may be used to implement aspects of the present disclosure. As described above, the BS may include a TRP. One or more components of the BS <NUM> and UE <NUM> may be used to practice aspects of the present disclosure. For example, antennas <NUM>, Tx/Rx <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be used to perform the operations described herein and illustrated with reference to <FIG>.

According to aspects, for a restricted association scenario, the base station <NUM> may be the macro BS 110c in <FIG>, and the UE <NUM> may be the UE 120y.

At the base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The control information may be for the Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid ARQ Indicator Channel (PHICH), Physical Downlink Control Channel (PDCCH), etc. The data may be for the Physical Downlink Shared Channel (PDSCH), etc. The processor <NUM> may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor <NUM> may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal.

The processor <NUM> and/or other processors and modules at the base station <NUM> may perform or direct, e.g., the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. The processor <NUM> and/or other processors and modules at the UE <NUM> may also perform or direct, e.g., the execution of the functional blocks illustrated in <FIG>, and/or other processes for the techniques described herein. The memories <NUM> and <NUM> may store data and program codes for the BS <NUM> and the UE <NUM>, respectively.

The illustrated communications protocol stacks may be implemented by devices operating in a <NUM> system (e.g., a system that supports uplink-based mobility).

A first option <NUM>--a shows a split implementation of a protocol stack, in which implementation of the protocol stack is split between a centralized network access device (e.g., an ANC <NUM> in <FIG>) and distributed network access device (e.g., DU <NUM> in <FIG>).

A second option <NUM>--b shows a unified implementation of a protocol stack, in which the protocol stack is implemented in a single network access device (e.g., access node (AN), new radio base station (NR BS), a new radio Node-B (NR NB), a network node (NN), or the like.

<FIG> illustrates various components that may be utilized in a wireless communications device <NUM> that may be employed within the wireless communication system from <FIG>. The wireless communications device <NUM> is an example of a device that may be configured to implement the various methods described herein. The wireless communications device <NUM> may be an BS <NUM> from <FIG> or any of user equipments <NUM>.

The wireless communications device <NUM> may include a processor <NUM> which controls operation of the wireless communications device <NUM>. The processor <NUM> may also be referred to as a central processing unit (CPU). Memory <NUM>, which may include both read-only memory (ROM) and random access memory (RAM), provides instructions and data to the processor <NUM>. A portion of the memory <NUM> may also include non-volatile random access memory (NVRAM). The instructions in the memory <NUM> may be executable to implement the methods described herein.

The wireless communications device <NUM> may also include a housing <NUM> that may include a transmitter <NUM> and a receiver <NUM> to allow transmission and reception of data between the wireless device <NUM> and a remote location. The transmitter <NUM> and receiver <NUM> may be combined into a transceiver <NUM>. A single or a plurality of transmit antennas <NUM> may be attached to the housing <NUM> and electrically coupled to the transceiver <NUM>. The wireless communications device <NUM> may also include (not shown) multiple transmitters, multiple receivers, and multiple transceivers.

The wireless communications device <NUM> may also include a signal detector <NUM> that may be used in an effort to detect and quantify the level of signals received by the transceiver <NUM>. The signal detector <NUM> may detect such signals as total energy, energy per subcarrier per symbol, power spectral density and other signals. The wireless communications device <NUM> may also include a digital signal processor (DSP) <NUM> for use in processing signals.

Additionally, the wireless communications device <NUM> may also include an encoder <NUM> for use in encoding signals for transmission. The encoder may also store the encoded signals in a circular buffer (not shown) and perform rate matching on the encoded signals (e.g., by implementing operations <NUM>, shown in <FIG>). Further, the wireless communication device <NUM> may include a decoder <NUM> for use in decoding received signals.

The various components of the wireless communications device <NUM> may be coupled together by a bus system <NUM>, which may include a power bus, a control signal bus, and a status signal bus in addition to a data bus. The processor <NUM> may be configured to access instructions stored in the memory <NUM> to perform connectionless access, in accordance with aspects of the present disclosure discussed below.

<FIG> is a simplified block diagram illustrating an encoder, in accordance with certain aspects of the present disclosure. <FIG> illustrates a portion of a radio frequency (RF) modem <NUM> that may be configured to provide an encoded message for wireless transmission (e.g., using polar codes described below). In one example, an encoder <NUM> in a wireless device (e.g., BS <NUM> or a UE <NUM>) receives a message <NUM> for transmission. The message <NUM> may contain data and/or encoded voice or other content directed to the receiving device. The encoder <NUM> encodes the message using a suitable modulation and coding scheme (MCS), typically selected based on a configuration defined by the BS <NUM> or another network entity. The encoded bitstream <NUM> is then stored in circular buffer and rate-matching is performed on the stored encoded bitstream, for example, according to aspects of the present disclosure described in more detail below. After the encoded bitstream <NUM> is rate-matched, the encoded bitstream <NUM> may then be provided to a mapper <NUM> that generates a sequence of TX symbols <NUM> that are modulated, amplified and otherwise processed by TX chain <NUM> to produce an RF signal <NUM> for transmission through antenna <NUM>.

<FIG> is a simplified block diagram illustrating a decoder, in accordance with certain aspects of the present disclosure. <FIG> illustrates a portion of a RF modem <NUM> that may be configured to receive and decode a wirelessly transmitted signal including an encoded message (e.g., a message encoded using a polar code as described below). In various examples, the modem <NUM> receiving the signal may reside at a user equipment, at a base station, or at any other suitable apparatus or means for carrying out the described functions. An antenna <NUM> provides an RF signal <NUM> (i.e., the RF signal produced in <FIG>) to an access terminal (e.g., UE <NUM>). An RX chain <NUM> processes and demodulates the RF signal <NUM> and may provide a sequence of symbols <NUM> to a demapper <NUM>, which produces a bitstream <NUM> representative of the encoded message.

A decoder <NUM> may then be used to decode m-bit information strings from a bitstream that has been encoded using a coding scheme (e.g., a Polar code). The decoder <NUM> may comprise a Viterbi decoder, an algebraic decoder, a butterfly decoder, or another suitable decoder. In one example, a Viterbi decoder employs the well-known Viterbi algorithm to find the most likely sequence of signaling states (the Viterbi path) that corresponds to a received bitstream <NUM>. The bitstream <NUM> may be decoded based on a statistical analysis of LLRs calculated for the bitstream <NUM>. In one example, a Viterbi decoder may compare and select the correct Viterbi path that defines a sequence of signaling states using a likelihood ratio test to generate LLRs from the bitstream <NUM>. Likelihood ratios can be used to statistically compare the fit of a plurality of candidate Viterbi paths using a likelihood ratio test that compares the logarithm of a likelihood ratio for each candidate Viterbi path (i.e. the LLR) to determine which path is more likely to account for the sequence of symbols that produced the bitstream <NUM>. The decoder <NUM> may then decode the bitstream <NUM> based on the LLRs to determine the message <NUM> containing data and/or encoded voice or other content transmitted from the base station (e.g., BS <NUM>).

<FIG> is a diagram <NUM> showing an example of a DL-centric subframe, which may be used by one or more devices (e.g., BS <NUM> and/or UE <NUM>) to communicate in the wireless network <NUM>.

The DL-centric subframe may also include a common UL portion <NUM>. The common UL portion <NUM> may sometimes be referred to as an UL burst, a common UL burst, and/or various other suitable terms. The common UL portion <NUM> may include feedback information corresponding to various other portions of the DL-centric subframe. For example, the common UL portion <NUM> may include feedback information corresponding to the control portion <NUM>. Non-limiting examples of feedback information may include an ACK signal, a NACK signal, a HARQ indicator, and/or various other suitable types of information. The common UL portion <NUM> may include additional or alternative information, such as information pertaining to random access channel (RACH) procedures, scheduling requests (SRs), and various other suitable types of information. As illustrated in <FIG>, the end of the DL data portion <NUM> may be separated in time from the beginning of the common UL portion <NUM>. One of ordinary skill in the art will understand that the foregoing is merely one example of a DL-centric subframe and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

<FIG> is a diagram <NUM> showing an example of an UL-centric subframe, which may be used by one or more devices (e.g., BS <NUM> and/or UE <NUM>) to communicate in the wireless network <NUM>. The UL -centric subframe may include a control portion <NUM>. The control portion <NUM> may exist in the initial or beginning portion of the UL-centric subframe. The control portion <NUM> in <FIG> may be similar to the control portion described above with reference to <FIG>. The UL-centric subframe may also include an UL data portion <NUM>. The UL data portion <NUM> may sometimes be referred to as the payload of the UL-centric subframe. The UL portion may refer to the communication resources utilized to communicate UL data from the subordinate entity (e.g., UE) to the scheduling entity (e.g., UE or BS). In some configurations, the control portion <NUM> may be a physical DL control channel (PDCCH).

As illustrated in <FIG>, the end of the control portion <NUM> may be separated in time from the beginning of the UL data portion <NUM>. The UL-centric subframe may also include a common UL portion <NUM>. The common UL portion <NUM> in <FIG> may be similar to the common UL portion <NUM> described above with reference to <FIG>. The common UL portion <NUM> may additional or alternative include information pertaining to channel quality indicator (CQI), sounding reference signals (SRSs), and various other suitable types of information. One of ordinary skill in the art will understand that the foregoing is merely one example of an UL-centric subframe and alternative structures having similar features may exist without necessarily deviating from the aspects described herein.

As noted above, polar codes are used to encode a stream of bits for transmission. Polar codes are the first provably capacity-achieving coding scheme with almost linear (in block length) encoding and decoding complexity. Polar codes are widely considered as a candidate for error-correction in the next-generation wireless systems. Polar codes have many desirable properties such as deterministic construction (e.g., based on a fast Hadamard transform), very low and predictable error floors, and simple successive-cancellation (SC) based decoding.

Polar codes are linear block codes of length N=<NUM>n where their generator matrix is constructed using the nth Kronecker power of the matrix <MAT> denoted by Gn, also referred to as a Hadamard matrix of order n. For example, Equation (<NUM>) shows the resulting generator matrix for n=<NUM>.

According to certain aspects, a codeword may be generated (e.g., by a BS) by using the generator matrix to encode a number of input bits (e.g., information bits). For example, given a number of input bits u=(u<NUM>, u<NUM>,. , uN-<NUM>), a resulting codeword vector x=(x<NUM> , x<NUM>,. , xN-<NUM>) may be generated by encoding the input bits using the generator matrix G. This resulting codeword is then rate matched (e.g., using techniques described herein) and transmitted by a base station over a wireless medium and received by a UE.

When the received vectors are decoded (e.g., by the UE) using a Successive Cancellation (SC) decoder (e.g., decoder <NUM>), every estimated bit, ûi, has a predetermined error probability given that bits u<NUM>i-<NUM> were correctly decoded, that tends towards either <NUM> or <NUM>. Moreover, the proportion of estimated bits with a low error probability tends towards the capacity of the underlying channel. Polar codes exploit a phenomenon called channel polarization by using the most reliable K bits to transmit information, while setting, or freezing, the remaining (N-K) bits to a predetermined value, such as <NUM>, for example as explained below.

For very large N, polar codes transform the channel into N parallel "virtual" channels for the N information bits. If C is the capacity of the channel, then there are almost N*C channels which are completely noise free and there are N(<NUM> - C) channels which are completely noisy. The basic polar coding scheme then involves freezing (i.e., not transmitting) the information bits to be sent along the completely noisy channel and sending information only along the perfect channels. For short-to-medium N, this polarization may not be complete in the sense there could be several channels which are neither completely useless nor completely noise free (i.e., channels that are in transition). Depending on the rate of transmission, these channels in the transition are either frozen or they are used for transmission.

Aspects of the present disclosure relate to a rate-matching scheme for transmission of information using polar codes. Rate matching is a process whereby the number of bits to be transmitted is matched to the available bandwidth of the number of bits allowed to be transmitted (e.g., the number of bits that can be carried in an allocation of transmission resources). In certain instances, the amount of data to be transmitted is less than the available bandwidth, in which case all the data to be transmitted (and one or more copies of the data) will be transmitted (a technique called repetition). In other instances, the amount of data to be transmitted exceeds the available bandwidth, in which case a certain portion of the data to be transmitted will be omitted from the transmission using a technique called puncturing and/or a technique called shortening.

<FIG> illustrates an example process <NUM> for polar encoding and rate matching information, according to aspects of the present disclosure. Information bits <NUM> may be encoded with a polar encoder <NUM> to produce encoded bits at <NUM>. The encoded bits may be collected into a circular buffer (e.g., a virtual circular buffer implemented in memory of a device) at <NUM>. Some of the encoded bits are selected for puncturing, shortening, or repetition at <NUM>. The stream of encoded bits that is produced is then interleaved at <NUM> and provided to a transmit chain for transmission.

<FIG> illustrates an exemplary circular buffer <NUM>, according to aspects of the present disclosure not falling under the scope of the claims. For example, in LTE, a tail biting convolutional code (TBCC) of rate <NUM>/<NUM> may be used for rate matching control channels and other types of channels, which is typically performed using a circular buffer. In the example, the bits of the channel may be encoded using three polynomials. Still in the example, after encoding a stream of bits, the resultant encoded bits from the three polynomials are put into the circular buffer one by one. For example, with reference to <FIG>, code bits from the first polynomial are placed in the circular buffer in the range of [<NUM>, N-<NUM>]. Further, code bits from the second polynomial are placed in the circular buffer in the range of [N, 2N-<NUM>], and code bits from the third polynomial are placed in the circular buffer in the range of [2N, 3N-<NUM>].

Once the coded bits are stored in the circular buffer, rate matching may be performed. For example, assuming an allocated block size of 'M', if M = 3N, then no repetition, puncturing, or shortening (i.e., rate matching) is performed. However, if M > 3N, then repetition may be performed clockwise from 3N around the circular buffer. Additionally, if M < 3N, then puncturing and/or shortening may be performed counterclockwise from 3N-<NUM> around the circular buffer.

In NR, polar codes of size (N) may be used to encode a stream of bits for transmission. However, in some cases, using the rate matching scheme described above (e.g., for TBCC codes) may lead to performance loss when used with polar codes, for example, when the size of the circular buffer is not a power of <NUM> (e.g., the block length constraint of polar codes).

As noted above, rate-matching may involve puncturing, repeating, or shortening certain bits of the encoded bits stored in the circular buffer, for example, as illustrated in <FIG>. Whether puncturing, repeating, or shortening is used may be determined by the wireless communications device based, at least in part, on the allocated coded block size, M, and the target coded block size, N.

For example, if M>N, the wireless communications device performs rate matching by repeating M-N (M minus N) encoded bits (e.g., Rbits) based on the Polar code of size N starting from the zeroth position in the circular buffer and proceeding clockwise around the circular buffer until position Rbits-<NUM> in the circular buffer, for example, as illustrated in <FIG>. According to aspects of the present disclosure, Rbits may be repeated at the end of the stream of encoded bits stored in the circular buffer.

In aspects of the present disclosure, if M<N, then the wireless communications device may perform rate matching by either puncturing or shortening certain bits of the stored encoded bits. For example, if M<N and M>=βK (where β is an integer and represents the reciprocal of the effective coded rate used to encode the stream of bits), then the wireless communications device punctures N-M encoded bits (e.g., Pbits) based on the Polar code of size N, starting at the zeroth position in the circular buffer and proceeding clockwise around the circular buffer, as illustrated in <FIG>.

According to aspects of the present disclosure, if M<N and M< βK, the wireless communications device shortens N-M encoded bits (e.g., Pbits) based on the Polar code N, starting from position N-<NUM> in the circular buffer and proceeding counterclockwise around the circular buffer, for example, as illustrated in <FIG>.

<FIG> is a diagram <NUM> illustrating a block-level interlacing technique for rate matching, according to previously known techniques. The polar encoder <NUM> uses a polar code of size N to encode a stream of bits to generate a stream of encoded output bits <NUM>. That stream of encoded output bits is divided into <NUM> blocks at <NUM>. The blocks are then interlaced by being placed in a circular buffer in a different order at <NUM>. An allocation of transmission resources of size M is allocated for transmission of the stream of bits. If M is less than N, then some of the blocks may be punctured, as shown at <NUM>, or shortened, as shown at <NUM>. If M is greater than N, then some of the blocks may be repeated, as shown at <NUM>. This technique of rate matching has a granularity of N/<NUM> (e.g., an entire block of size N/<NUM> may be punctured or shortened), and this can be very large when N is very large, which may be a drawback in some cases.

<FIG> is a diagram <NUM> illustrating a bit-level interlacing technique for rate matching, according to previously known techniques. The polar encoder <NUM> uses a polar code of size N to encode a stream of K bits (e.g., information bits and a CRC) to generate a stream of encoded output bits <NUM>. That stream of encoded output bits is divided into <NUM> blocks at <NUM>. The bits of the middle two blocks are then interlaced by at <NUM>. An allocation of transmission resources (e.g., a coded bit length) of size M is allocated for transmission of the stream of bits. If M is greater than N, then some of the bits may be repeated, as shown at <NUM>. If M is less than N, then some of the bits may be punctured, as shown at <NUM>, or shortened, as shown at <NUM>. This technique of rate matching may have decreased performance when a number of bits to puncture or shorten is greater than N;<NUM>.

Thus, aspects of the present disclosure propose an efficient rate-matching scheme for channels using polar codes. In aspects of the present disclosure, bits are selected for modification (e.g., puncturing and/or shortening) based on row weights of a Hadamard matrix. According to aspects of the present disclosure, bits corresponding to the smallest row weights may be punctured to provide better performance than previously known techniques. In aspects of the present disclosure, bits corresponding to the largest row weights may be shortened to provide better performance than previously known techniques.

In the discussion below the following parameters are used:.

<FIG> illustrates example operations <NUM> for wireless communications, for example, for rate-mating of a control channel using polar codes. Operations <NUM> may be performed by a wireless communications device, such as a base station (BS <NUM>), user equipment <NUM>, and/or wireless communications device <NUM>.

Operations <NUM> begin at <NUM> by encoding K information bits using a polar code with a mother code length, N, to generate a stream of encoded bits.

At <NUM>, the wireless communications device stores a portion of the encoded bits in a circular buffer of size N.

At <NUM>, the wireless communications device reorders P blocks of the circular buffer according to row weights of a Hadamard matrix J.

At <NUM>, the wireless communications device interlaces the encoded bits of the blocks having a same row weight.

At <NUM>, the wireless communications device selects, based on the row weights, a subset of the encoded bits in the blocks to modify.

At <NUM>, the wireless communications device modifies the selected subset of the encoded bits.

At <NUM>, the wireless communications device transmits the encoded bits in the P blocks, subsequent to modifying the selected subset of the encoded bits, via transmission resources.

<FIG> is a diagram <NUM> of an exemplary algorithm for determining bits to be punctured and/or shortened for rate-matching, in accordance with certain aspects of the present disclosure. The encoded (e.g., polar encoded) bits are represented at <NUM>. At <NUM>, a wireless communications device divides the mother code length N bits into P blocks, each containing N/P bits. i.e., block! has bits <NUM> through (N/P)-<NUM>, block2 has bits N/P through (N/P)*<NUM>-<NUM>, etc. <FIG> is illustrated using a typical value of P of <NUM>, but other values of P that are integral powers of <NUM> may be used. At <NUM>, the wireless communications device reorders the blocks according to the row weights of a Hadamard matrix. The Hadamard matrix J is constructed with order of log<NUM>(P). The row weights of J may be calculated by adding the values in each row of J. The Hadamard matrix of order <NUM> is reproduced below, with a table showing the row weights.

Thus, as shown at <NUM>, sorting the blocks according to row weights of the Hadamard matrix J results in the fifth block being placed before the fourth block. When sorting the blocks, the blocks remain in the natural order for blocks corresponding to rows with a same row weight.

At <NUM>, the wireless communications device performs a bit-level interlace of the bits, after the block reordering at <NUM>. The interlacing interlaces bits of blocks having a same row weight. Thus, in <FIG>, the bits from blocks <NUM>, <NUM>, and <NUM> are interlaced, and the bits from blocks <NUM>, <NUM>, and <NUM> are interlaced.

At <NUM>, if bits are to be punctured, the bits selected for puncturing are the 1st N-M bits from <NUM>. If bits are to be shortened, the bits selected for shortening are the end N-M bits from <NUM>. The bits selected for shortening are labeled at <NUM>.

According to aspects of the present disclosure, the modification operation in block <NUM> of <FIG> may be a repetition operation. The wireless communications device may select the first N-M bits in the blocks for repetition.

As mentioned above, other values of P may be used with the disclosed techniques. According to aspects of the present disclosure, row weights of a Hadamard matrix of order <NUM>, for P = <NUM>, are shown in the table below.

According to aspects of the present disclosure, the techniques described above provide an efficient rate-matching algorithm(s) with a good trade-off between decoding complexity and decoding performance. For example, by using the techniques described above to puncture, repeat, or shorten encoded bits before transmission, decoding complexity and latency at a receiving device may be reduced because these bits do not need to be decoded, which, in turn, saves processing resources and power at the receiving device.

In some cases, rather than actually transmitting a frame, a device may have an interface to output a frame for transmission. For example, a processor may output a frame, via a bus interface, to an RF front end for transmission. Similarly, rather than actually receiving a frame, a device may have an interface to obtain a frame received from another device. For example, a processor may obtain (or receive) a frame, via a bus interface, from an RF front end for transmission.

For example, means for transmitting, means for receiving, means for determining, means for performing (e.g., rate-matching), means for encoding, means for, puncturing, means for repeating, means for shortening, and/or means for generating may comprise one or more processors or antennas at the BS <NUM> or UE <NUM>, such as the transmit processor <NUM>, controller/processor <NUM>, receive processor <NUM>, or antennas <NUM> at the BS <NUM> and/or the transmit processor <NUM>, controller/processor <NUM>, receive processor <NUM>, or antennas <NUM> at the UE <NUM>.

The processor may be implemented with one or more general-purpose and/or specialpurpose processors.

Claim 1:
A method (<NUM>) of wireless communications, comprising:
encoding (<NUM>) K information bits using a polar code with a mother code length, N, to generate a stream of encoded bits;
storing (<NUM>) the encoded bits in a circular buffer of size N,
dividing the encoded bits in the circular buffer into P blocks, each block containing N/P encoded bits, wherein P is an integral power of <NUM>;
selecting (<NUM>) a subset of the encoded bits in the P blocks to modify;
modifying (<NUM>) the selected subset of the encoded bits, wherein the modification is one of a shortening, a puncturing, and a repetition; and
transmitting (<NUM>) the encoded bits in the P blocks, subsequent to modifying the selected subset of the encoded bits, via transmission resources, the method characterized by further comprising, after the dividing and before the selecting (<NUM>):
reordering (<NUM>) the P blocks of the circular buffer according to row weights of a Hadamard matrix J, wherein the Hadamard matrix J has an order that is equal to log<NUM>(P); and
interlacing (<NUM>) the encoded bits of the reordered blocks having a same row weight of the Hadamard matrix J; the method being further characterized in that the selecting (<NUM>) is based on the row weights of the Hadamard matrix J.