RNTI encoding and blind decoding of PAC codes for pdcch

Abstract

An apparatus configured to apply a convolutional precoder with a time-varying polynomial to an information vector to generate a precoded vector, wherein coefficients of the time-varying polynomial are generated by a pseudo-random number generator (PRNG) using a radio network temporary identifier (RNTI) as an initialization seed, generate a polarization-adjusted convolution (PAC) codeword based on the precoded vector and transmit the PAC codeword.

Description

Attorney Docket No. 30164 / 100602Ref. No. P70119WO1 RNTI Encoding and Blind Decoding of PAC Codes for PDCCH Inventors: Arman Fazeli Chaghooshi, Louay Jalloul and Mohamad MansourPriori ty / Incorporation By Reference

[0001] This application claims priority to U. S. Provisional Application Serial No. 63 / 719, 498 filed on November 12, 2024, and entitled " RNTI Encoding and Blind Decoding of PAC Codes for PDCCH, ” the entirety of which is incorporated by reference herein.Background

[0002] The physical downlink control channel (PDCCH) in a cellular network carries downlink control information (DCI ), which may include, e. g., control and scheduling information. In current radio networks, including 5G New Radio (NR) and 4G Long Term Evolution (LTE ), the encoding process for the PDCCH includes the attachment of a cyclic redundancy check (CRC) to the DCI payload. In 5G NR, a 24-bit CRC is masked with a radio network temporary identifier (RNTI ) and the sequence is passed to a polar encoder to generate a codeword for transmission by the PDCCH. Polar codes are generally effective for error correction, however, they have limitations that necessitate the use of the CRC for error detection in 5G NR PDCCH.Summary

[0003] Some example embodiments are related to an apparatus having memory coupled to processing circuitry, the processing circuitry configured to apply a convolutional precoder with a time-varying polynomial to an information vector to generate a precoded vector, wherein coefficients of the time-varying polynomial are generated by a pseudo-random number generatorAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 ( PRNG) using a radio network temporary identifier (RNTI ) as an initialization seed, generate a polarization-adjusted convolution ( PAC) codeword based on the precoded vector and transmit the PAC codeword.

[0004] Other example embodiments are related to an apparatus having memory coupled to processing circuitry, the processing circuitry configured to apply a polarization-adjusted convolutional (PAC) decoder to bits of physical downlink control channel (PDCCH) candidates, the PAC decoder applying coefficients generated from a pseudo-random number generator ( PRNG) that uses a radio network temporary identifier (RNTI ) as an initialization seed, the PAC decoder calculating metrics representing confidence levels for estimated codewords corresponding to the PDCCH candidates and determine, based on the metrics, whether a PDCCH candidate is valid.

[0005] Still further example embodiments are related to an apparatus having memory coupled to processing circuitry, the processing circuitry configured to apply an encryption algorithm to a codeword, wherein a radio network temporary identifier (RNTI ) is used as a key to the encryption algorithm and the codeword is scrambled by a pseudo-random number generator ( PRNG) and transmit the codeword.Brief Description of the Drawings

[0006] Fig. 1 shows a diagram illustrating an encoding process of a physical downlink control channel ( PDCCH) using legacy polar codes.

[0007] Fig. 2 shows a diagram illustrating a legacy blind decoding process of the PDCCH.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0008] Fig. 3 shows a diagram illustrating an encoding process using polarization-adjusted convolutional (PAG) codes according to various example embodiments.

[0009] Fig. 4 shows a chart illustrating the performance of PAC codes according to one example study.

[0010] Fig. 5 shows a diagram illustrating an encoding process using PAC codes in which a time-varying convolutional precoder utilizes a radio network temporary identifier (RNTI) sequence as input to the precoder according to various example embodiments.

[0011] Fig. 6 shows a diagram illustrating an end-to-end PAC encoding and blind detection scheme in which a radio network temporary identifier (RNTI) is utilized as an initialization seed to the encoding and decoding process according to various example embodiments.

[0012] Fig. 7 shows an example network arrangement according to various example embodiments.

[0013] Fig. 8 shows an example UE according to various example embodiments.

[0014] Fig. 9 shows an example base station according to various example embodiments.Detailed Description

[0015] The example embodiments may be further understood with reference to the following description and the related appendedAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 drawings, wherein like elements are provided with the same reference numerals. The example embodiments relate to channel encoding and decoding schemes comprising Polarization-Adjusted Convolutional (PAC) codes. In some aspects of the example embodiments, a radio network temporary identifier (RNTI) is used by a transmitter as a seed for randomizing the PAC encoding / decoding such that, if the RNTI used by the receiver is the same as the RNTI used by the transmitter, e. g., the encoder and the decoder are in synchronization, the decoding is successful.

[0016] The example embodiments are described with regard to a user equipment (UE). However, reference to a UE is merely provided for illustrative purposes. The example embodiments may be utilized with any electronic component that may establish a connection to a network and is configured with the hardware, software, and / or firmware to exchange signaling and / or data with the network. Therefore, the UE as described herein is used to represent any electronic component.

[0017] The example embodiments are also described with reference to cellular networks. It is noted that certain aspects of the 5G New Radio (NR) network are described herein. However, reference to a 5G NR network is merely provided for illustrative purposes. In particular, the example embodiments may be suitable for implementation in a next generation radio access network, e. g., a 6G network or beyond 6G network. The example embodiments may be utilized with any network capable of implementing channel coding and decoding functionalities similar to those described herein. Therefore, reference to a network such as the 5G NR network should be understood as representingAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 any type of network implementing functionalities based on and / or s imilar to the 5G NR network.

[0018] The example embodiments are al so described with regard to the phys ical downlink control channel ( PDCCH ) and downl ink control information ( DCI ). However, aspects o f the example embodiments may be appl icable to channel s other than the PDCCH, such as, e. g., the PDSCH, or any other wireles s channel.

[0019] The example embodiments are al so described with regard to the Radio Network Temporary Identi fier (RNT I ). In current 5G NR standards, the Radio Network Temporary Identi fier (RNT I ) is a key identi f ier embedded in the PDCCH to speci fy the intended recipient o f the DCI. The 5G RNTI i s a 1 6-bit identi f ier.Exi sting RNT I types in 5G NR include: paging RNTI ( P-RNT I ); system information RNTI ( S I-RNT I ); random acces s RNT I (RA-RNTI ); cel l RNT I ( C-RNTI ); temporary cell RNTI ( TC-RNT I ); modulation coding scheme cel l RNTI (MCS-C-RNT I ); conf igured schedul ing RNT I ( CS-RNT I ); transmit power control RNT I ( TPC-RNT I ) including TPC physical upl ink control channel RNT I ( TPC-PUCCH-RNT I ), TPC physical upl ink shared channel RNT I ( TPC-PUSCH-RNTI ), and TPC sounding re ference s ignal RNT I ( TPC-SRS-RNT I ); interruption RNT I ( INT-RNT I ); s lot format indication RNTI ( S FI-RNT I ); and semi-persi stent channel state information RNT I ( SP-CS I-RNT I ). Each o f the RNTI types i s as sociated with a value or a range o f values de fined by standards, e. g., 3GPP Technical Speci f ications ( TS ). Some RNT I s are common to all UEs in a cel l, e. g., P-RNTI and S I -RNTI, some RNTI s are common to a group, e. g., TPC-RNT I, and some RNT I s are UE- speci f ic, e. g., C-RNT I. The RNT I i s used in PDCCH transmis s ions to di f ferentiate UEs or groups of UEs. One or more RNTI s may be ass igned to a UE, whi le others may be determined by the UE or prede f ined.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0020] Current 5G NR operations include a cyclic redundancy check ( CRC ) to as s i st in error detection for PDCCH reception. The CRC in 5G NR compri ses 24 bits and i s appended to the DCI payload before encoding. The RNTI masks the last 1 6 bits o f the CRC, e. g., by an exclus ive OR (XOR) operation. During bl ind detection, the UE attempts to decode multiple PDCCH candidates and appl ies the RNT I to the CRC during veri fication. I f the CRC pas ses for any candidate ( e. g., the CRC matches ), the UE identi f ies the corresponding DCI as val id and relevant, al lowing it to proces s control information even without prior knowledge o f where the PDCCH i s located. The UE then fol lows the schedul ing or control instructions included in the val id DCI. I f the CRC fai ls for any candidate ( e. g., the CRC does not match), the UE identi f ies the corresponding DCI as inval id and di scards the candidate. Thi s proces s ensures that each UE applies only to the DCI that i s intended for the UE and so that the UE knows the usage o f the DCI.

[0021] The 3GPP standards that speci fy RNT I encoding and detection in 5G NR PDCCH include 3GPP TS 38. 211, which details physical channels and modulation techniques, including how RNT I s are appl ied in 5G. 3GPP TS 38. 212 covers multiplexing and channel coding, speci fying the RNT I mas king process and how polar coding i s used for DCI transmi s sion. 3GPP TS 38. 213 focuses on the phys ical layer procedures, particularly how UEs perform blind decoding and uti l i ze search spaces to detect control information.

[0022] Fig. 1 shows a diagram 100 il lustrating an encoding proces s o f a phys ical downlink control channel ( PDCCH ) us ing legacy polar codes according to one example. The encodingAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 process of the diagram 100 may be implemented by a transmitter in a 5G NR network, e. g., a base station, gNB, TRP, etc.

[0023] The transmitter receives raw data 102 from higher layers which, in the case of the PDCCH, includes downlink control information (DCI ). The raw data 102 comprises a binary vector of length k that is first processed by a CRC precoder 104 that computes ( / c0- k CRC bits and appends them to the data vector 102, optionally masking it with the RNTI sequence 106 that is known to both the transmitter device (e. g., gNB) and receiver device (e. g., UE). The output of the CRC precoder 104 is protected data 108 comprising a binary vector of length k0.

[0024] The protected data 108 is passed to a rate profiler 110 that utilizes a frozen bit map 112, known to both the transmitter (e. g., base station) and receiver (e. g., UE), to place the k0bits into an information vector 114 of length n, wherein (n — / c0) zeros are inserted in the other locations of the vector 114 according to the frozen bit map. The (n — k0~) bits are known as frozen bits and their value and locations are known at the time of the decoding if the decoder is attempting to decode a PDCCH candidate with the same code parameters n and k.

[0025] The information vector 114 is then passed to a rate-1 polar transform 116 of length n to generate a coded vector 118. The coded vector 118 is optionally passed through a ratematching block 120 to comply with the parameters dictated by standard, e. g., to ensure the codeword 122 matches a transmission rate for the transmission resources. The output of the coding process is a codeword 122 that may be furtherAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 processed, e. g., mapped to modulation symbols and resource elements, for transmission by the PDCCH.

[0026] Fig. 2 shows a diagram 200 illustrating a legacy blind decoding process of the PDCCH according to one example. The decoding process of the diagram 200 may be implemented by a receiver in a 5G NR network, e. g., a UE.

[0027] The receiver performs demodulation and PDCCH preprocessing 202 to define a search space and assemble up to 44 candidates that are passed to a polar decoder 206 as soft bits 204. The soft bits 204 may be in the form of log likelihood ratios (LLR). The full set of candidates may include a first subset of candidates with valid DCI vectors that are intended for the UE and a second subset of candidates with invalid DCI vectors that are not intended for the UE. However, the UE is not aware of the exact locations of the valid DCI (s). The decoder 206 is tasked with going through these candidates and attempting to decode them. The decoder 206 utilizes the RNTI mask as well as the CRC information to confirm if any of these candidates carry valid DCI. The decoder output 208 could be a single vector or a list of polar codewords, in the case of successive cancellation list (SCL) decoding, to be described in greater detail below, which are all cross checked against the RNTI-masked CRC 210 for the secondary verification. When the CRC passes 212, the DCI 214 is processed, e. g., applied by the UE.

[0028] Polarization Adjusted Convolutional (PAC) codes were published in 2019. Later improvements include SCL decoding of PAC codes, a novel rate-profile design, and decoder simplifications. Since the development of PAC codes, the PAC codes have been shown to achieve superior error correctionAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 performance compared to conventional polar codes without requiring the enhancements that are provided through CRC-precoding. PAC codes generally do not employ CRC blocks, although, in some cases, a CRC may also be used.

[0029] Fig. 3 shows a diagram 300 illustrating an encoding process using polarization-adjusted convolutional (PAC) codes according to one example. In contrast to the polar coding scheme described with regard to Fig. 1, there is no CRC precoding block. Raw data bits 302 are passed to a rate profiler 304, which inserts (n — k) frozen values (zeros) into the raw data 302 according to a frozen bit map 306 that is known to both the encoder and the decoder. The output of the rate profiler 304 is an information vector 308 of length n, including both data bits and frozen bits, denoted as v”-1.

[0030] In PAC encoding, the information vector 308 is then passed to a rate-1 convolutional transform 310 before the rate-1 polar transform 316. A convolutional code is a type of errorcorrection code that generates coded symbols (such as parities) via the sliding application of a binary polynomial function 312 to the input stream, in this case, the information vector 308. The output of the convolutional transform 310 is a precoded vector 314 denoted as UQ-1. As a result of the sliding window process, any bit such as u, may be represented as a binary linear combination of the preceding Vi according to: Wi= / (id,...,iy_t) (Equation 1), where f is a linear combination whose coefficients are determined according to the degree-t binary polynomial. The precoded vector 314 is passed to the rate-1 polar transform 316 of length n to generate a PAC codeword 318, denoted as c”-1.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0031] Fig. 4 shows a chart 400 demonstrating the performance of PAC codes according to one example study. The chart 400 illustrates the frame error rate (FER) relative to SNR for three coding / decoding schemes utilized for transmissions over a binary-input additive white Gaussian noise (BIAWGN) channel, including a polar code with SC decoding, a polar code with SCL decoding, and a PAC code. The chart 400 further includes a BIAWGN dispersion approximation, which serves as a theoretical lower bound. The performance gap between polar codes and PAC codes is evident from the chart 400, the PAC code having a significantly lower FER than the polar codes. The FER / BLER improvement achieved by PAC codes was further verified in multiple additional references for 5G compliant polar codes with strong SCL decoders.

[0032] SCL decoding, with minor modifications, is suitable for decoding PAC codes with no performance loss in moderate regions. This is an encouraging result from the implementation perspective as it establishes the high similarity of design between polar and PAC codes, which makes them suitable for integration into the standards. Additionally, effective results may be achieved by selecting a randomized polynomial of sufficient degree at every index. In other words, the fixed relation in Equation 1 is replaced with: u;-= iy_i,..., ) (Equation 2).

[0033] According to various example embodiments, a PAC encoding scheme is described for channel encoding, in particular PDCCH encoding. As described in detail above, PDCCH encoding schemes currently implemented in 5G NR utilize CRC precoding to assist in both error detection and UE identification. The CRC typically comprises 24 bits in 5G NR. The PAC encoding schemeAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 described herein obviates the need for CRC precoding, relative to the legacy CRC-aided polar codes, which may reduce the overhead associated with PDCCH transmissions, improving performance and / or freeing up the bits typically used for the CRC for data communication. It is noted that, in some embodiments to be described in greater detail below, a CRC may be used, if desired. However, in view of the performance of the PAC codes, this is not required and, if the CRC is used, it may be smaller than the 24 bits used in NR, e. g., 4 or 8 bits.

[0034] In example embodiments, a method is described to embed the RNTI sequence into the randomizer as a seed, which transforms the conventional PAC codes into PAC codes with timevarying convolutional pre-coders. As described above, the RNTI sequence may serve as a key for the UE to unlock DCI messages intended for the UE over the PDCCH. As described above, the RNTI sequence is assigned to the UE by the network or is otherwise known to both the UE and the network. Thus, embedding the RNTI sequence into the encoding process provides RNTI verification in a manner different from the RNTI masking of the CRC currently used in 5G NR.

[0035] Fig. 5 shows a diagram 500 describing an encoding process using PAC codes in which a time-varying convolutional precoder utilizes a radio network temporary identifier (RNTI ) sequence as input to the precoder according to various example embodiments. Similar to the PAC encoding scheme described in Fig. 3, there is no CRC pre-coding block and raw data bits 502 are passed directly to a rate profiler 504 that utilizes a frozen bit map to output an information vector 506.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0036] According to the example embodiments, the information vector 506 is then passed to a time varying convolutional precoder 508 that uses the RNTI sequence 510 as input, to be described in greater detail below. The precoder 508 outputs a precoded vector 512 that is passed to the rate-1 polar transform 514 to generate a PAC codeword 516.

[0037] The example embodiments describe methods for using PAC codes for PDCCH transmission without any CRC-precoding while further embedding the RNTI information into the transmitted codeword. The example embodiments further describe methods for extracting valid DCI and discarding invalid DCI during the blind detection stage at the receiver.

[0038] In some aspects of the example embodiments, the fixed-polynomial convolutional pre-coding stage of existing PAC codes is replaced with a time-varying polynomial of the same degree whose coefficients are randomly generated using a Pseudo Random Number Generator (PRNG) initiated with the RNTI sequence as its initialization seed. The RNTI sequence is utilized as the seed to the pseudo-random generator device so that, when the key matches the lock, the pseudo-random generators on Tx and Rx side are in synchronization without requiring any look-up tables.

[0039] The UE can track the pre-coding equations at the time of the blind decoding and, when a correct PDCCH candidate is detected, it can be passed on for post-decoding processing. By contrast, when the UE attempts to decode an invalid / unintended PDCCH candidate, the mismatch in the PRNG seed causes a mismatch in decoding trajectories. This mismatch can be detected by monitoring the path metrics throughout the SCL decoding without requiring any CRC verifications.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0040] Fig. 6 shows a diagram 600 describing an end-to-end PAC encoding and blind detection scheme in which a radio network temporary identifier (RNTI ) is utilized as an initialization seed to the encoding and decoding process according to various example embodiments.

[0041] Raw data 602, which in the case of PDCCH is mostly DCI, is denoted by a binary vector d = d0, d1,.... dk-1. The raw data 602 is passed on to a rate-profiler 604, which inserts (n - k) zeros in between the data bits according to some predefined frozen bit mappings.

[0042] The rate-profiler 604 may be configured according to various techniques. Multiple known frozen bit maps may be suitable, and the example embodiments are compatible with any choice of frozen bit maps. In some aspects, a reinforcement learning (RL) algorithm may be used for rate profile construction, e. g., Q-Learning, to solve a maze traversing game for discovering better rate-profilers than those commonly used.

[0043] The output of the rate-profiler 604 is called the uncoded vector 606 and is denoted by v =. The uncoded vector 606 is passed on to the rate-1 convolutional pre-coder 608 with a time-varying polynomial. The coefficients 614 of the time-varying polynomial are denoted as a- coefficients 614. The a coefficients 614 are binary values that are generated pseudo-randomly at the time of the encoding based on the RNTI 610 as an initialization seed.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0044] In various aspects of the example embodiments, thecoefficients are generated by any method of pseudo-random number generation (PRNG). In some example embodiments, a Linear Feedback Shift Register (LFSR) 612 is utilized to generate a sequence of binary values based on a linear feedback function. The LFSR 612 comprises a series of flip-flops arranged in a row, with each flip-flop holding one bit of data. The feedback is derived by performing a bitwise XOR operation on selected bits (called taps) and feeding the result back into the register.LFSRs are commonly used for generating pseudo-random sequences. Accordingly, using a LFSR 612 comprises a simple and hardware friendly method for pseudo-random number generation.

[0045] PRNGs appear random but are actually deterministic and, given the same initialization seed, the PRNG produces the same sequence of numbers. In some aspects of the example embodiments, the RNTI sequence associated with the PDCCH encoding process (e. g., the RNTI sequence identifying the type of DCI and, in some cases, identifying a specific UE) serves as the initialization seed for the LFSR.

[0046] To be described in greater detail below, the same RNTI sequence can be used to initiate the same PRNG circuit for randomized generations on the decoder side, allowing the transmitter and the receiver to share these randomized values in perfect synchronization without requiring either side to store large look-up tables for the encoding process and the decoding process. Even though the precoding coefficients are generated randomly, their values are known to the decoder and can be used to trace the decoding trajectories at the time of decoding.However, when the decoder attempts to decode unintended PDCCHAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 candidates, or pure noise, the uncertainty in the randomized precoder breaks down the decoder and makes it unable to decode a valid PAC codeword with high confidence.

[0047] Accordingly, the RNTI sequence 610 is introduced into the PAC encoding process as an initialization seed of a random number generator 612, the random number generator 612 generating time varying polynomial coefficients 614 to be used by the rate-1 time-varying convolutional pre-coder 608. The output of convolutional pre-coder 608, referred to herein as the convolutionally-pre-coded vector 616, or simply the pre-coded vector 616, is denoted by u =...,un-1. The input-output relation of this block is given by Vf: ui=ui+ a1vi-1+ a2vi-2+ ... + atvi-t(Equation 3) where the additions are mod 2 (XOR), and t denotes the degree on the precoding polynomial. Variables with negative subscripts are default set to 0.

[0048] The pre-coded vector 616 is then passed on to a rate-1 polar transformation 618 of length n, which can be represented by matrix multiplication in the binary domain using the polar[1 01®generator matrix G — j111, where m = log n and ® is the Kronecker product. In some aspects of these example embodiments, this is the same transformation that is used in legacy polar codes.

[0049] The output of the rate-1 polar transform 618 comprises the PAG codeword 620, denoted by c = c0, c1,.... cn-1. The PAG codeword 620 may be transmitted over a channel 622. It is noted that the channel 622 of Fig. 6 represents a simplified collection of the transformations and processing stages that occur in the middleAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 between the encoder block in the transmitter and the decoder block in the receiver, such as modulation and demodulation.

[0050] On the receiver side, the receiver performs demodulation and PDCCH processing 624 (e. g., serving as a dispatcher for the decoder 628 ). The dispatcher is tasked at packaging the corresponding soft bits for these candidates and passing these to the decoder 628. In the present example embodiment, the soft bits are in the form of LLRs 626.

[0051] The decoder 628 initiates decoding instances with the proper LLR input values, frozen bit maps, and the RNTI sequence for LFSR initialization. In 5G NR PDCCH, up to 44 candidates may be processed with the decoder concurrently. The decoder 628 according to the example embodiments may be configured to process any number of PDCCH candidates, e. g., a maximum number defined in future specifications.

[0052] According to various example embodiments, the decoder 628 calculates metrics that relate to the confidence of the decoder in the estimated codeword. In the present example, SCL decoding compares path metrics 636 with certain pre-computed thresholds 638, to be described in greater detail below. If the encoder and decoder are in synchronization, e. g., using the same RNTI, then the decoder can track the decoding, e. g., the path metrics 636 will reveal a high confidence in the decoding. If the encoder and the decoder are not in synchronization, then the decoding traj ectories will be thrown off, e. g., the path metrics 636 will reveal a low confidence in the decoding. In some embodiments, the estimated codeword of a PDCCH candidate is determined to be invalid 640 when the path metrics exceed a certain threshold 638 at any time during the decoding process.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1 If the threshold 638 is not exceeded, then the estimated codeword is determined to be valid 642.

[0053] It is noted that additional checks may be made on the estimated codewords initially determined to be valid. For example, a DCI post-processing can be used as an additional check. Additionally, in some embodiments, a CRC may be added to the data bits. The CRC may be shorter than the 24-bit CRC used in 5G NR, e. g., may be 4 bits or 8 bits.

[0054] Any polar / PAC decoding algorithm may be employed on the Rx side. In some embodiments, Successive Cancellation (SC) decoding and its variations, such as Successive Cancellation List (SCL) decoding, are highly suitable for blind detection according to the present embodiments.

[0055] A successive cancellation (SC) decoding method is based on estimating the pre-coded bits one by one in a sequential manner, where the hard decided values (0, 1 ) are assigned tou0, as an approximation for u.

[0056] SC decoding is based on a certain schedule of LLR combining and hard decisions over the polar encoding circuit. At step i, to estimate Uj, the decoder calculates a likelihood (or LLR), which may be viewed as P(ûi= 0) / P(ui= 1), conditioned on the decoding traj ectory for the bits estimated so far. Recalling Equation 3 described above ( i Ui =vi+ a1vi-1+ ... + atvi-t), two scenarios are possible based on the frozen bit map that is used to setup the decoder.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0057] If V is frozen, the value of it, depends on the previously decoded bits and hence may be computed on the fly. Such a method of computing the frozen values on the fly is commonly known as dynamic frozen value assignment in the literature.

[0058] If Vi is non-frozen, the value of u, depends both on the unknown bit Vi as well as the previously decoded bits. In this case, the decoder relies on the correctness of the decoded bits so far and uses the newly computed soft bits to make a hard decision on the value of Ui.

[0059] SC decoding and its variations are unable to fix an incorrect decision that is made during the decoding process and suffer from the error propagation issue. However, SCL decoding is designed such that it tracks a list of traj ectories at any given index, usually denoted by the parameter L, which increases the chance of maintaining the correct traj ectory in the list and improves the error correction probability. Small values of L can be sufficient to aid the most likely traj ectory to be preserved throughout the decoding process, which indicates that the SCL decoding may approximate the error correction performance of the Maximum Likelihood (ML) decoder with reasonable precision.

[0060] Now, looking at the RNTI sequence and how it serves as the seed for the PRNG, two scenarios may occur for the decoder. If both the encoder and the decoder utilize the same RNTI sequence, the precoding in this scheme is in perfect synchronization, which means that the only source of errors throughout the decoding can be the decoder' s inability to produce highly reliable soft bits for hard decisions.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0061] If the UE attempts to decode an invalid PDCCH candidate, there will be a mismatch in the RNTI sequences, which means that during decoding the i-th bit, the effect of the so-far-decoded bits of Equation 3 is highly unpredictable, which makes any soft bits computed for Uj not useful. The uncertainty in the way of combining the previously decoded bits quickly sends the decoder off the track after decoding only a few frozen bits and the message will not be recoverable by the UE.

[0062] The SCL decoder can differentiate between these two scenarios by tracking the path metric variable, which is an internal variable to the decoder, used to monitor the reliability of the decoding trajectories for the candidates on the list. In the absence of the correct trajectory from the list in addition to mixing multiple incorrect decisions on the frozen indices, the path metric variables signal the decoder on low confidence, which may be used to terminate the decoding process.

[0063] Thus, the blind detection may be performed by tracking the decoder' s confidence in the decoded vectors, which in the case of SCL decoding is available via comparing the path metrics with certain pre-computed thresholds. The above discrimination method based on path metric allows the decoder to reliably separate valid DCI sequences from the invalid candidates and further terminate the decoding process in early stages as soon as the confidence levels fall below certain thresholds.

[0064] The elimination of the CRC from blind decoding process opens additional bits for data transmission, which may be utilized to enhance the code rate (e. g., throughput) or the error correction performance of the code, or both. Furthermore,Attorney Docket No. 30164 / 100602Ref. No. P70119WO1 not requiring specific CRCs creates a generic design for the encoder and decoder, which may provide additional flexibility to the device.

[0065] The proposed scheme replaces the 5G CRC-aided polar codes for PDCCH with PAC codes while improving the overall error probability and eliminating the requirement for CRC without requiring additional computational power. Such a scheme provides a method for early decoding termination with minimal additional computing costs. The proposed schemes use flexible thresholdbased methods for blind detection of PDCCH candidates that can eliminate the need for CRC entirely.

[0066] The DCI encoding process comprises a low-complexity and randomized embedding of RNTI sequence via a time-varying convolutional pre-coder. The semi randomized encoder also provides measures of privacy in the shared control channel (CCH). The semi randomized encoder provides beneficial error correction performance measured in terms of BLER given that the randomization mimics the performance of random linear codes.

[0067] SCL decoding with dynamic frozen value determination can decode PAC codes with time-varying convolutional pre-coder as they did for the state-of-the-art PAC codes with a fixed-polynomial convolutional pre-coder. The path metrics, and internal SCL decoding variable associated with the different decoding traj ectories in the list, is sensitive towards incorrect decisions. A mismatch in the seeds used for the precoding results in the decoder making many incorrect decisions throughout the decoding, which is detectable by monitoring the path metrics. A path metric threshold comparison allows the UE to detect incorrect PDCCH candidates and terminate the decodingAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 as soon as the path metrics surpas s the threshold. The smooth and dynamic early termination scheme of PAG codes i s an e f f icient method o f early termination which al lows the UE to save computational power during the PDCCH proces sing.

[0068] In additional aspects of the present disclosure, the RNT I can be utili zed in a general encryption scheme for secure communication. In one embodiment, the RNT I can serve as the encryption key whi le the PRNG can serve as the scrambler.

[0069] Fig. 7 shows an example network arrangement 700 according to various example embodiments. The example network arrangement 700 includes a UE 710. The UE 710 may be any type o f electronic component that i s conf igured to communicate via a network, e. g., mobi le phones, tablet computers, des ktop computers, smartphones, embedded devices, wearables, Internet o f Things ( loT ) devices, etc. An actual network arrangement may include any number o f UEs being used by any number o f users.Thus, the example o f one UE 710 is merely provided for i l lustrative purposes.

[0070] The UE 710 may be configured to communicate with one or more networks. In the example o f the network arrangement 700, the network with which the UE 710 may wireles s ly communicate i s a 5G NR radio acces s network ( RAN) 720. However, as described above, the example embodiments may be more readi ly implemented in a future generation RAN, e. g., 6G RAN.

[0071] The UE 710 may also communicate with other types o f networks ( e. g., 5G cloud RAN, a next generation RAN (NG-RAN), a legacy cellular network, etc. ) and the UE 710 may al so communicate with networks over a wired connection. With regardAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 to the example embodiments, the UE 710 may establish a connection with the 5G NR RAN 720. Therefore, the UE 710 may have a 5G NR chipset to communicate with the NR RAN 720.

[0072] The 5G NR RAN 720 may be portions of a cellular network that may be deployed by a network carrier (e. g., Verizon, AT& T, T-Mobile, etc. ). The RAN 720 may include cells or base stations that are configured to send and receive traffic from UEs that are equipped with the appropriate cellular chip set. In this example, the 5G NR RAN 720 includes the gNB 720A and the gNB 720B. However, reference to a gNB is merely provided for illustrative purposes, any appropriate base station or cell may be deployed (e. g., Node Bs, eNodeBs, HeNBs, eNBs, gNBs, gNodeBs, macrocells, microcells, small cells, femtocells, etc. ).

[0073] Any association procedure may be performed for the UE 710 to connect to the 5G NR RAN 720. For example, as discussed above, the 5G NR RAN 720 may be associated with a particular network carrier where the UE 710 and / or the user thereof has a contract and credential information (e. g., stored on a SIM card). Upon detecting the presence of the 5G NR RAN 720, the UE 710 may transmit the corresponding credential information to associate with the 5G NR RAN 720. More specifically, the UE 710 may associate with a specific cell (e. g., gNB 720A).

[0074] The network arrangement 700 also includes a cellular core network 730, the Internet 740, an IP Multimedia Subsystem ( IMS) 750, and a network services backbone 760. The cellular core network 730 manages the traffic that flows between the cellular network and the Internet 740. The IMS 750 may be generally described as an architecture for delivering multimedia services to the UE 710 using the IP protocol. The IMS 750 mayAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 communicate with the cellular core network 730 and the Internet 740 to provide the multimedia services to the UE 710. The network services backbone 760 is in communication either directly or indirectly with the Internet 740 and the cellular core network 730. The network services backbone 760 may be generally described as a set of components (e. g., servers, network storage arrangements, etc. ) that implement a suite of services that may be used to extend the functionalities of the UE 710 in communication with the various networks.

[0075] Fig. 8 shows an example UE 710 according to various example embodiments. The UE 710 will be described with regard to the network arrangement 700 of Fig. 7. The UE 710 may represent any electronic device and may include a processor 805, a memory arrangement 810, a display device 815, an input / output ( I / O) device 820, a transceiver 825, and other components 830. The other components 830 may include, for example, an audio input device, an audio output device, a battery that provides a limited power supply, a data acquisition device, ports to electrically connect the UE 710 to other electronic devices, sensors to detect conditions of the UE 710, etc.

[0076] The processor 805 may be configured to execute a plurality of engines for the UE 710. For example, the engines may include a FAC encoding and decoding engine 835 for performing operations related to PAG decoding, e. g., for PDCCH candidates, as described in detail above. The UE 710 may also be configured for PAG encoding for uplink channels.

[0077] The above referenced engine being an application (e. g., a program) executed by the processor 805 is only an example. The functionality associated with the engines may alsoAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 be represented as a separately incorporated component of the UE 710 or may be a modular component coupled to the UE 710, e. g., an integrated circuit with or without firmware. For example, the integrated circuit may include input circuitry to receive signals and processing circuitry to process the signals and other information. The engines may also be embodied as one application or separate applications. In addition, in some UEs, the functionality described for the processor 805 is split among two or more processors such as a baseband processor and an applications processor. The example embodiments may be implemented in any of these or other configurations of a UE.

[0078] The memory arrangement 810 may be a hardware component configured to store data related to operations performed by the UE 710. The display device 815 may be a hardware component configured to show data to a user while the I / O device 820 may be a hardware component that enables the user to enter inputs. The display device 815 and the I / O device 820 may be separate components or integrated together such as a touchscreen.

[0079] The transceiver 825 may be a hardware component configured to establish a connection with the 5G NR-RAN 720, an LTE-RAN (not pictured), a legacy RAN (not pictured), a WLAN (not pictured), etc. Accordingly, the transceiver 825 may operate on a variety of different frequencies or channels (e. g., set of consecutive frequencies). The transceiver 825 includes circuitry configured to transmit and / or receive signals (e. g., control signals, data signals). Such signals may be encoded with information implementing any one of the methods described herein. The processor 805 may be operably coupled to the transceiver 825 and configured to receive from and / or transmit signals to the transceiver 825. The processor 805 may beAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 configured to encode, decode and / or process signals (e. g., signaling from a base station of a network) for implementing any one of the methods described herein.

[0080] In the example of Fig. 8, the processor 805 and the radio frequency (RF) circuitry (e. g., transceiver 825) are illustrated as separate components. However, in some example embodiments, the RF circuitry and the processing circuitry may be integrated into the same chip, e. g., a system on chip that includes a baseband processor and RF circuitry.

[0081] Fig. 9 shows an example base station 900 according to various example embodiments. The base station 900 may represent the gNB 720A, the gNB 720B or any other access node through which the UE 710 may establish a connection and manage network operations. The base station 900 may operate as the MN or the SN as described in the examples above.

[0082] The base station 900 may include a processor 905, a memory arrangement 910, an input / output ( I / O) device 915, a transceiver 920, and other components 925. The other components 925 may include, for example, an audio input device, an audio output device, a battery, a data acquisition device, ports to electrically connect the base station 500 to other electronic devices and / or power sources, etc.

[0083] The processor 905 may be configured to execute a plurality of engines for the UE 710. For example, the engines may include PAG encoding and decoding engine 930 for performing operations related to PAG encoding, e. g., for PDCCH transmissions, as described in detail above. The base station 900 may also be configured for PAG decoding for uplink channels.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0084] The memory arrangement 910 may be a hardware component configured to store data related to operations performed by the base station 900. The I / O device 915 may be a hardware component or ports that enable a user to interact with the base station 900.

[0085] The transceiver 920 may be a hardware component configured to exchange data with the UE 710 and any other UE in the network arrangement 700. The transceiver 920 may operate on a variety of different frequencies or channels (e. g., set of consecutive frequencies). The transceiver 920 includes circuitry configured to transmit and / or receive signals (e. g., control signals, data signals). Such signals may be encoded with information implementing any one of the methods described herein. The processor 905 may be operably coupled to the transceiver 920 and configured to receive from and / or transmit signals to the transceiver 920. The processor 905 may be configured to encode, decode and / or process signals (e. g., signaling from a UE) for implementing any one of the methods described herein.

[0086] In the example of Fig. 9, the processor 905 and the radio frequency (RF) circuitry (e. g., transceiver 920) are illustrated as separate components. However, in some example embodiments, the RF circuitry and the processing circuitry may be integrated into the same chip, e. g., a system on chip that includes a baseband processor and RF circuitry.Examples

[0087] In a first example, a method, comprising applying a convolutional precoder with a time-varying polynomial to anAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 information vector to generate a precoded vector, wherein coefficients of the time-varying polynomial are generated by a pseudo-random number generator (PRNG) using a radio network temporary identifier (RNTI ) as an initialization seed, generating a polarization-adj usted convolution ( PAG) codeword based on the precoded vector and transmitting the PAC codeword.

[0088] In a second example, the method of the first example, further comprising applying a rate profiler to data bits, the data bits comprising a binary vector of length k, to generate the information vector.

[0089] In a third example, the method of the second example, wherein the rate profiler inserts (n — k') zeros into the data bits according to a frozen bit mapping, the information vector comprising a binary vector of length n.

[0090] In a fourth example, the method of the first example, wherein the coefficients of the time-varying polynomial of the convolutional precoder are randomized by the PRNG based on the RNTI.

[0091] In a fifth example, the method of the first example, wherein the PRNG comprises a linear feedback shift register (LFSR).

[0092] In a sixth example, the method of the first example, wherein generating the PAC codeword comprises applying a polar transformation to the precoded vector.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0093] In a seventh example, the method of the sixth example, wherein the polar transformation transforms the information vector by a polar generator matrix to generate the PAG codeword of length n, wherein the method further comprises mapping the PAG codeword to modulation symbols and mapping the modulation symbols to resource elements (RE) for transmission.

[0094] In an eighth example, the method of the first example, wherein the PAG codeword is transmitted by a physical downlink control channel ( PDCCH).

[0095] In a ninth example, the method of the first example, further comprising adding a cyclic redundancy check (CRC) prior to generating the information vector, the CRC comprising 4 bits or 8 bits.

[0096] In a tenth example, a processor configured to perform any of the methods of the first through ninth examples.

[0097] In an eleventh example, a user equipment (UE ) configured to perform any of the methods of the first through ninth examples.

[0098] In a twelfth example, a base station configured to perform any of the methods of the first through ninth examples.

[0099] In a thirteenth example, a method, comprising applying a polarization-adj usted convolutional ( PAG) decoder to bits of physical downlink control channel ( PDCCH) candidates, the PAG decoder applying coefficients generated from a pseudo-random number generator ( PRNG) that uses a radio network temporary identifier (RNTI ) as an initialization seed, the PAG decoderAttorney Docket No. 30164 / 100602Ref. No. P70119WO1 calculating metrics representing confidence levels for estimated codewords corresponding to the PDCCH candidates and determining, based on the metrics, whether a PDCCH candidate is valid.

[0100] In a fourteenth example, the method of the thirteenth example, wherein, when the PDCCH candidate is valid, the method further comprises extracting downlink control information (DCI ) from the PDCCH candidate.

[0101] In a fifteenth example, the method of the thirteenth example, wherein the bits of the PDCCH candidates are soft bits comprising log likelihood ratios (LLR).

[0102] In a sixteenth example, the method of the thirteenth example, wherein the PAC decoder applies a predefined frozen bit mapping to the soft bits of the PDCCH candidates.

[0103] In a seventeenth example, the method of the sixteenth example, wherein the PAC decoder applies dynamic frozen value assignment to compute frozen bit values.

[0104] In an eighteenth example, the method of the thirteenth example, further comprising tracking a path metric variable for the PDCCH candidates during decoding to monitor a reliability of decoding traj ectories of the PDCCH candidates and determining, based on at least the path metric, whether the PDCCH candidate is valid.

[0105] In a nineteenth example, the method of the eighteenth example, wherein determining the PDCCH candidate is valid is based on comparing the path metric variable for the PDCCH candidate to a predetermined threshold.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0106] In a twentieth example, the method of the nineteenth example, further comprising discarding the PDCCH candidate when the predetermined threshold is exceeded at any time during the decoding.

[0107] In a twenty first example, the method of the thirteenth example, further comprising terminating a PAC decoding process prior to completion of the PAC decoding process.

[0108] In a twenty second example, the method of the thirteenth example, wherein the PAC decoder applies successive cancellation (SC) decoding or successive cancellation list (SCL) decoding to estimate precoded bits sequentially.

[0109] In a twenty third example, the method of the thirteenth example, wherein the PAC decoder applies belief propagation decoding, successive cancellation flip decoding, or sequential stack decoding.

[0110] In a twenty fourth example, the method of the thirteenth example, wherein the metrics representing the confidence levels for the estimated codewords do not comprise path metrics.

[0111] In a twenty fifth example, a processor configured to perform any of the methods of the thirteenth through twenty fourth examples.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0112] In a twenty sixth example, a user equipment (UE) configured to perform any of the methods of the thirteenth through twenty fourth examples.

[0113] In a twenty seventh example, a base station configured to perform any of the methods of the thirteenth through twenty fourth examples.

[0114] In a twenty eighth example, a method, comprising applying an encryption algorithm to a codeword, wherein a radio network temporary identifier (RNTI ) is used as a key to the encryption algorithm and the codeword is scrambled by a pseudorandom number generator (PRNG) and transmitting the codeword.

[0115] In a twenty ninth example, a processor configured to perform the method of the twenty eighth example.

[0116] In a thirtieth example, a user equipment (UE) configured to perform the method of the twenty eighth example.

[0117] In a thirty first example, a base station configured to perform the method of the twenty eighth example.

[0118] Although this application described various embodiments each having different features in various combinations, those skilled in the art will understand that any of the features of one embodiment may be combined with the features of the other embodiments in any manner not specifically disclaimed or which is not functionally or logically inconsistent with the operation of the device or the stated functions of the disclosed embodiments.Attorney Docket No. 30164 / 100602Ref. No. P70119WO1

[0119] Some embodiments described herein may include use of learning and / or non-learning-based process (es). The use may include collecting, pre-processing, encoding, labeling, organizing, analyzing, recommending and / or generating data.Entities that collect, share, and / or otherwise utilize user data should provide transparency and / or obtain user consent when collecting such data.

[0120] It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

[0121] It will be apparent to those skilled in the art that various modifications may be made in the present disclosure, without departing from the spirit or the scope of the disclosure. Thus, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their eguivalent.

Claims

1. Attorney Docket No. 30164 / 1006022.Ref. No. P70119WO1 What is claimed:

1. An apparatus comprising memory coupled to processing circuitry, the processing circuitry configured to:4.apply a convolutional precoder with a time-varying polynomial to an information vector to generate a precoded vector, wherein coefficients of the time-varying polynomial are generated by a pseudo-random number generator (PRNG) using a radio network temporary identifier (RNTI ) as an initialization seed;5.generate a polarization-adjusted convolution (PAC) codeword based on the precoded vector; and6.transmit the PAC codeword.

2. The apparatus of claim 1, the processing circuitry further configured to:8.apply a rate profiler to data bits, the data bits comprising a binary vector of length k, to generate the information vector.

3. The processor of claim 2, wherein the rate profiler inserts (n — fc) zeros into the data bits according to a frozen bit mapping, the information vector comprising a binary vector of length n.

4. The apparatus of claim 1, wherein the coefficients of the time-varying polynomial of the convolutional precoder are randomized by the PRNG based on the RNTI.Attorney Docket No. 30164 / 10060211.Ref. No. P70119WO1 5. The apparatus of claim 1, wherein the PRNG comprises a linear feedback shift register (LFSR).

6. The apparatus of claim 1, wherein generating the PAC codeword comprises the processing circuitry applying a polar transformation to the precoded vector.

7. The apparatus of claim 6, wherein the polar transformation transforms the information vector by a polar generator matrix to generate the PAC codeword of length n, wherein the processing circuitry is further configured to:14.map the PAC codeword to modulation symbols; and15.map the modulation symbols to resource elements (RE) for transmission.

8. The apparatus of claim 1, wherein the PAC codeword is transmitted by a physical downlink control channel (PDCCH).

9. The apparatus of claim 1, wherein the processing circuitry is further configured to:18.add a cyclic redundancy check (CRC) prior to generating the information vector, the CRC comprising 4 bits or 8 bits.

10. An apparatus comprising memory coupled to processing circuitry, the processing circuitry configured to:Attorney Docket No. 30164 / 10060220.Ref. No. P70119WO1 apply a polarization-adjusted convolutional (PAC) decoder to bits of physical downlink control channel (PDCCH) candidates, the PAC decoder applying coefficients generated from a pseudorandom number generator (PRNG) that uses a radio network temporary identifier (RNTI) as an initialization seed, the PAC decoder calculating metrics representing confidence levels for estimated codewords corresponding to the PDCCH candidates; and determine, based on the metrics, whether a PDCCH candidate is valid.

11. The apparatus of claim 10, wherein, when the PDCCH candidate is valid, the processing circuitry is further configured to:22.extract downlink control information (DCI ) from the PDCCH candidate.

12. The apparatus of claim 10, wherein the bits of the PDCCH candidates are soft bits comprising log likelihood ratios (LLR).

13. The apparatus of claim 10, wherein the PAC decoder applies a predefined frozen bit mapping to the soft bits of the PDCCH candidates.

14. The apparatus of claim 13, wherein the PAC decoder applies dynamic frozen value assignment to compute frozen bit values.

15. The apparatus of claim 10, wherein the processing circuitry is further configured to:Attorney Docket No. 30164 / 10060227.Ref. No. P70119WO1 track a path metric variable for the PDCCH candidates during decoding to monitor a reliability of decoding trajectories of the PDCCH candidates; and28.determine, based on at least the path metric, whether the PDCCH candidate is valid.

16. The apparatus of claim 15, wherein the processing circuitry determines the PDCCH candidate is valid based on comparing the path metric variable for the PDCCH candidate to a predetermined threshold.

17. The apparatus of claim 16, wherein the processing circuitry is further configured to:31.discard the PDCCH candidate when the predetermined threshold is exceeded at any time during the decoding.

18. The apparatus of claim 10, wherein the processing circuitry is further configured to:33.terminate a PAC decoding process prior to completion of the PAC decoding process.

19. The apparatus of claim 10, wherein the PAC decoder applies successive cancellation (SC) decoding or successive cancellation list (SCL) decoding to estimate precoded bits sequentially.

20. An apparatus comprising memory coupled to processing circuitry, the processing circuitry configured to:Attorney Docket No. 30164 / 10060236.Ref. No. P70119WO1 apply an encryption algorithm to a codeword, wherein a radio network temporary identifier (RNTI ) is used as a key to the encryption algorithm and the codeword is scrambled by a pseudo-random number generator (PRNG); and37.transmit the codeword.

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