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).

Document <NPL> discusses polar codes design and proposes a new order index for polar codes, which can further simplify the encoding procedure. Polar codes are constructed by channel polarization phenomenon. However, this phenomenon is depended on the channel states. For different channel states, "good" and "bad" bit indices are usually different. One method to select the frozen set is to use different frozen sets for different channel states, such as for different coding rates and different codelengths. With another method, only one ordered index sequence QNmax of length Nmax is needed for encoding, which may reduce the memory cost.

Document <NPL> describes a design of polar code for NR control channel and data channel using a PC (Parity-Check)-polar code construction, in which a sub-set of the frozen-bit set is selected, the "PC frozen-bit set", over which a parity-check function is set up for error correction. PC-frozen bits and Frozen bits are selected from an ordered bits position sequence (Q) according to descending reliability order by pre-flagging. Then, information bit positions are selected one by one from the rightmost to the leftmost (in a reliability descending order) skipping the flagged bit positions, until the number of the information bit positions reaches information bits length K. It is shown that the polar code has good and stable performance with a PC-SCL decoder and supports the fine-granularity rate-matching scheme for all NR scenarios, including eMBB/mMTC/uRLLC and control channel.

It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for encoding using dynamic frozen polar codes. In aspects, the techniques may be used in multi-slice networks, such as NR (new radio access technology or <NUM> technology).

NR may support various wireless communication services, such as Enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. <NUM> beyond), millimeter wave (mmW) targeting high carrier frequency (e.g. <NUM> or beyond), massive MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra reliable low latency communications (URLLC).

In NR, Polar codes may be used for forward error correction (FEC) to encode information transmitted on control channels. Generally, in Polar encoding, the most reliable channels are selected to carry information, and the rest of the bits are set to a fixed value (e.g., such as <NUM>), which are referred to as "frozen bits". However, as disclosed herein, performance can be improved by selecting some frozen bits to have values that depend on the information bits. Thus, aspects of the present disclosure present techniques for Polar encoding using dynamic frozen (PCF) bits. PCF bits may be used for error detection and/or error correction.

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 invention 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> nextgen/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 control channel encoding using dynamic frozen polar codes. For example, a BS <NUM> or UE <NUM> may perform polar encoding/encoding for transmissions according to the techniques described herein. For example, the BS <NUM> and/or UE <NUM> may select channel indices in connection with encoding information bits, CRC bits, frozen bits, and dynamic frozen (PCF) bits and may transmit a polar coded message in accordance therewith.

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, a gNB, 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 also applicable to 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. It should be noted that <NUM> is only an example and NR resource blocks may span other subcarrier bandwidths such as <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

In LTE, the basic transmission time interval (TTII) or packet duration is the <NUM> subframe. slots) depending on the tone-spacing (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

Additionally, each radio frame may consist of <NUM> subframes with a total 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 respect to <FIG> and <FIG>. MIMO transmissions with preceding may also be supported. 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 an example logical architecture of a distributed radio access network (RAN) <NUM>, which may be implemented in the wireless network <NUM> illustrated in <FIG>.

The logical architecture may be used to illustrate fronthaul definition.

The logical architecture may share features and/or components with LTE.

The logical architecture may enable cooperation between and among TRPs <NUM>. For example, cooperation may be present within a TRP and/or across TRPs via the ANC <NUM>.

According to aspects, a dynamic configuration of split logical functions may be present within the logical architecture.

<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. A transmit ('I'X) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 432a through 432t.

The symbols from the transmit processor <NUM> may be preceded by a TX MIMO processor <NUM> if applicable, further processed by the demodulators 454a through 454r (e.g., for SC-FDM, etc.), and transmitted to the base station <NUM>.

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>, <FIG> and <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>, <FIG> and <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.

<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 a 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 select a rate code to encode the signals and may store the encoded signals in a circular buffer (not shown). The encoder may also perform rate matching on the encoded signals, as described below. Further, the wireless communication device <NUM> may include a decoder <NUM> for use in decoding received signals, for example, by using Polar encoding with dynamic frozen bits as will be described in more detail below.

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 base station (e.g., BS <NUM>) or a UE (e.g., UE <NUM>) on the reverse path receives a message <NUM> for transmission. The message <NUM> may contain data and/or encoded voice or other content directed to the receiving device. In aspects, the message <NUM> is first input into a sequencer <NUM> that receives the message <NUM> and output the message <NUM> as a sequence of bits in a channel index order. In aspects, the sequencer <NUM> determines the channel index order for the sequence of bits. As discussed further herein, the sequencer <NUM> may be responsible for determining the channel indices for fixed frozen bits, information bits, and dynamic frozen (PCF) bits. For example the sequencer <NUM> may determine the channel indices for the fixed frozen bits, information bits, and dynamic frozen bits as shown in <FIG>. As will be discussed in more detail herein, the sequencer <NUM> may determine values for the dynamic frozen bits based on a function of all or a part of the previous information bits. 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. In some cases, the encoder <NUM> may select, from a set of rate codes, a rate code to be used to encode the message. The encoded bitstream <NUM> may then be stored in circular buffer and rate-matching may be performed on the stored encoded bitstream, for example, according to aspects presented 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 the access terminal, at the 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 demodulated 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 in-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>). In some cases, the decoder may combine LLRs associated with lower aggregation levels with LLRs associated with higher aggregation levels and use the combined LLRs to decode the bitstream <NUM>, for example, as described in greater detail below.

<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>. In some configurations, the DL data portion <NUM> may be a physical DL shared channel (PDSCIT).

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 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 may be used to encode a stream of bits for transmission. Polar codes are a 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. For example, Equation (<NUM>) shows the resulting generator matrix for n=<NUM>.

A codeword may be generated 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 may then be rate matched and transmitted.

When the received vectors are decoded) 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.

In new radio (NR) as described above, Polar codes may be used to encode information. For example, Polar codes may be used as forward error correction (FEC) for control channels (e.g., <NUM> control channels). Generally, cyclic redundancy check (CRC) bits can be added in the Polar codes (e.g., CRC-aided polar coding (CA-polar)) to improve the error rate performance and error detection. Generally, other types of "assistant bits" can also be used.

Because Polar codes are linear block codes with a recursively constructed generator matrix, a polar code of length N is built from the concatenation of two constituent polar codes of length Nv = N/<NUM>. This recursive construction is carried out in a way that polarizes the probability of correctly estimating bits: some bit estimates become more reliable and others becomes less reliable. As the blocklength increases, some bit estimates become more reliable and the rest become less reliable.

Each polar code bit-channel (e.g., channel index) is assigned a reliability value, used to determine which bits transmit information and which parity. Relative reliabilities may be known (e.g., stored and/or computed) by both encoders and decoders. The relative order of reliabilities can be dependent on the code length and on the signal-to-noise ratio (SNR) for which the code has been constructed. The reliabilities associated with the bit-channels can be determined, for example, by using the Bhattacharyya parameter, through the direct use of probability functions, or other reliability computation.

In Polar encoding, the most reliable channels (e.g., most reliable bit locations/positions) are typically selected to carry information (e.g., information bits), and the rest of the bits are set as a fixed value (e.g., <NUM>). These fixed bits may be referred to as frozen bits. However if some of the frozen bits are selected having values that depend on the information bits, the performance can be improved.

According to certain aspects, a bit sequence (e.g., ordering or arrangement of bits of a stream of bits) for bits input to a Polar encoder may be determined, where each bit in the bit sequence corresponds to (e.g., is selected/ordered/arranged/set/placed in the bit sequence based on) a channel index (e.g., bit location/position) having certain reliability metrics.

<FIG> illustrates example operations <NUM> for wireless communications. Operations <NUM> may be performed by an encoding device, which may be a wireless communications device, such as a base station (e.g., BS <NUM>), a user equipment (e.g., UE <NUM>), and/or other wireless communications device <NUM>.

Operations <NUM> begin at <NUM> by encoding a stream of bits using polar code, wherein the encoding includes setting a first set of bits of the stream of bits as dynamic frozen (PCF) bits. The PCF bits have values based on one or more information bits. At <NUM>, the encoding device transmits the encoded stream of bits.

Setting the dynamic frozen bits includes determining a set of most reliable bit positions. A second set of bits of the stream of bits can be selected as the one or more information bits (i. e, (e.g., K information bits). The information bits may include payload bits and/or cyclic redundancy check (CRC) bits (e.g., <NUM> CRC bits). The information bits may also include false alarm rate (FAR) bits. A set of the most reliable channel indices (e.g., bit positions) is selected for information bits. A third set of bits of the stream of bits are selected as fixed frozen bits. The selecting includes, at 1102a, selecting most reliable channel indices for the information bits and, at 1102b, selecting channel indices smaller than channel index for the first information bit for the fixed frozen bits. At 1102c, the remaining channel indices are selected for the dynamic frozen (PCF) bits.

According to certain aspects, the method further includes, at <NUM>, calculating the values of the dynamic frozen bits as a function of at least a portion of the previous information bits. For example, the function may be an XOR (exclusive or) function. The function may be a length-<NUM> cycle shift register.

According to certain aspects, the stream of bits may be a code block of a control channel. Each bit in the stream of bits may correspond to a channel indices. The channel indices of the fixed frozen bits, information bits, and/or the dynamic frozen bits may be determined independently for each stream of bits to be encoded.

<FIG> illustrates example operations <NUM> for wireless communications. Operations <NUM> may be performed by a decoding device, which may be a wireless communications device, such as a base station (e.g., BS <NUM>), user equipment (e.g., <NUM>), and/or wireless communications device <NUM>.

Operations <NUM> begin at <NUM> by receiving a polar encoded stream of bits including a first set of dynamic frozen bits having values based on one or more information bits. At <NUM>, the encoding device decodes the encoded stream of bits, wherein decoding the stream of bits includes decoding the dynamic frozen bits based on one or more previous information bits.

<FIG> is an exemplary wireless device <NUM> that may include means for performing the operations <NUM> for dynamic frozen polar code encoding described above with respect to <FIG>, in accordance with certain aspects of the present disclosure. Wireless device <NUM> may be a UE such as UE <NUM> described above or a BS such as BS <NUM> described above. According to certain aspects, the wireless device <NUM> may include one or antenna(s) <NUM> for receiving and/or transmitting a stream of bits, which may be an encoded stream of bits. As shown in <FIG>, the wireless device includes a sequencer <NUM> and an encoder <NUM>. The wireless device <NUM> may bits for encoding. For example, the wireless device <NUM> may include a stream of bits corresponding to code blocks of a control channel. Although not shown, wireless device may include a module (e.g., a processor) configured to generate information bits to be encoded for transmission to another wireless device.

According to certain aspects, sequencer <NUM> may include the information bit channel indices determination module <NUM> for determining the information channel indices. The information bit channel indices determination module <NUM> selects most reliable channel indices for the information bits. The sequencer <NUM> selects (e.g., set) the K most reliable channels as information channel indices, where K is equal to the number of information bits, which may include payload and CRC bits. Sequencer <NUM> includes fixed frozen bit channel indices determination module <NUM> configured to determine fixed frozen channel indices. The sequencer <NUM> selects (e.g., set) the channels before (i.e., having smaller/lower channel indices) the first information channel as the fixed frozen channel indices. For example, since these channel having the lower channel indices may be lower reliability, these are used for the frozen bits (e.g., padding). Sequencer <NUM> includes dynamic frozen bit channel indices determination module <NUM> for determining dynamic frozen channel indices. Sequencer <NUM> selects the remaining channels (i.e., the channel indices not selected for the information bits or the fixed frozen bits) may be selected (e.g., set) as the dynamic frozen channel indices.

<FIG> is an example of the channel selection for the information bits, fixed frozen bits, and dynamic frozen bits, in accordance with certain aspects of the present disclosure. As shown in <FIG>, the channel indices are ordered u0, u1, u2, u3. etc. The channel indices are associated with a reliability metric. The selection of the channel indices to use for encoding is based on the reliability metric associated with each channel index. As shown in <FIG>, the set of channel indices selected for the information bits is based on the reliability metric indicating those channels as the most reliable channels. The channel indices smaller than the first (lowest) channel index selected for encoding the information bits are selected for encoding fixed frozen bits. The remaining channels indices are selected for the dynamic frozen bits.

As used herein, channel indices may refer to virtual channels (e.g., the indices may map to frequency resources). In an example, each channel carries one bit.

CRC bits can be added to the information bits. For example, as shown in <FIG>, encoder <NUM> includes CRC encoding module <NUM>. CRC encoding module <NUM> may be configured to encode the payload (e.g., by adding CRC bits to the payload). CRC encoder module <NUM> may output K information bits. The K information bits can be put in the selected information channels.

As shown in <FIG>, the values of the dynamic frozen bits can be calculated. Sequencer <NUM> includes dynamic frozen bit value determination module <NUM>. For example, for a code length of length N bits, the channel index order may be denoted as u<NUM>, u<NUM>,. , uN-<NUM>. The set of information channels can be denoted as A, where |A| = K. For a given dynamic frozen bit, ui, dynamic frozen bit value determination module <NUM> may calculate the value of the bit based on (e.g., dependent on) previous information bits. For example, the value of the dynamic frozen bit may be calculated as: <MAT> where, i<NUM> < i,. , ij < i; i<NUM> ∈ A,. , ij ∈ A, and f is dynamic frozen function. According to certain aspects, the value of the dynamic frozen bit may be based on all or only a portion of the previous information bits. For example, the dynamic frozen function f may be an XOR (exclusive or) function of all of the previous information bits or an XOR function of part of the previous information bits.

As shown in <FIG>, encoder <NUM> may include Polar code module <NUM>. For example, after the dynamic frozen bits are calculated, the sequence u<NUM>,u<NUM>,. ,uN-<NUM> may be fed to the Polar code module <NUM> which may be configured to perform Polar encoding and output the coded bits. The output coded stream of bits may be transmitted to another wireless device, for example, via the antenna(s) <NUM>.

According to certain aspects, a sequencer may select (e.g., determine, set) channel indices for the information bits, frozen bits, and/or dynamic frozen bits. An encoder (e.g., a CRC encoder) may perform encoding on the information bits. The sequencer may also calculate the values of the dynamic frozen bits. For example, the encoder may add CRC bits to payload bits. Another encoder may perform the Polar encoding on the stream of bits including the information bits, frozen bits, and dynamic frozen bits.

According to certain aspects, each bit in the stream of bits may correspond to a channel index. The channel indices of the information bits, the fixed frozen bits, and/or the dynamic frozen bits may be determined independently for each stream of bits to be encoded (e.g., for each code block). For example, the most reliable channels may change over time. Thus, the positions (e.g., channel indices), and/or the values of the bits, determined for the information bits and, thus, for the fixed frozen bits and/or the dynamic frozen bits may vary over time as well.

Although not shown in <FIG>, a wireless device, such as wireless device <NUM> may include a decoder. On the decoding side, the decoder may receive the coded stream of bits. The decoder may decode the stream of bits in order, starting from the lower channel indices. Thus, the decoder may decode the fixed frozen bits first, and then information bits and dynamic frozen bits. In aspects, the decoder may use the information bits to decode the dynamic frozen bits, which may increase the decoding performance.

<FIG> illustrates example operations <NUM> for wireless communications. Operations <NUM> may be performed by an encoding device, which may be a wireless communications device, such as a BS (e.g., BS <NUM>), a UE (e.g., UE <NUM>), and/or other wireless communications device <NUM>.

Operations <NUM> begin at <NUM> by encoding a stream of bits using a polar code. As shown in <FIG>, the encoding includes selecting a first set of channel indices associated with the most reliable channels for encoding information bits (e.g., payload, CRC, and/or FAR bits) at 1502a, selecting a second set of the channel indices smaller than the channel index of the first information bit (e.g., the smallest channel index) for encoding fixed frozen bits at 1502b, and selecting the remaining channel indices for encoding PCF bits (e.g., <NUM> PCF bits) having values based on one or more of the information bits at 1502c. Different channel indices may be selected for different code blocks. Optionally, at <NUM>, the method includes CRC encoding the information bits before the polar encoding. The channel indices are associated with a reliability metric. The selection of the first set of channel indices is determined based on the reliability metric.

At <NUM>, the encoding device transmits the encoded stream of bits (e.g., one code block of a control channel, such as an eMBB control channel).

According to certain aspects, the values of each of the PCF bits can be calculated as a function of at least a portion of the previous information bits to that dynamic frozen bit. In some examples, the values are calculated using an XOR function.

In one example, K information bits may be used for an uplink control channel. The number of information bits for payload and FAR may be equal to or between <NUM> and <NUM>. In addition to the FAR bits, <NUM> assistance bits may be included, for example, <NUM> CRC bits and <NUM> PCF bits. The K information bits may be encoded with the <NUM> CRC bits. K' = K + <NUM> most reliable bits positions may be selected for the information and assistance bits. The <NUM> PCF bits may be assigned positions from the K' most reliable.

Techniques described herein provide advantages. Use of CRC-aided and PCF-added polar encoding improved code performance. The improved code performance enables better encoding and decoding, for example, faster and more accurate encoding and decoding. The improved encoding and decoding improves the performance of the encoders/decoders in the processing system and improves the experience in wireless communications.

The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified.

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 encoding, means for selecting, means for decoding, means for calculating, and/or means for setting 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>.

Claim 1:
A method (<NUM>) for wireless communications, comprising:
encoding (<NUM>) a stream of bits using a polar code, wherein the encoding includes:
selecting (1102a) a first set of channel indices consisting in the K most reliable channel indices for encoding information bits, where K is equal to the number of information bits, wherein the channel index order of the stream of bits input to the polar coding using a generator matrix G is denoted as u<NUM>, u<NUM>, ... , uN-<NUM> for a polar code of length N bits, wherein the channel indices are associated with a reliability metric, and wherein the first set of channel indices is determined based on the reliability metric;
selecting (1102b) a second set of the channel indices consisting in the set of channel indices smaller than the channel index of the first information bit for encoding fixed frozen bits; and
selecting (1102c) the remaining channel indices within u<NUM>, u<NUM>, ... , uN-<NUM> as the channel indices for encoding dynamic frozen bits having values based on one or more of the information bits; and
transmitting (<NUM>) the encoded stream of bits.