Patent Description:
Thanks to success of long term evolution (LTE)/LTE-advanced (LTE-A) for <NUM> mobile communication, interest in future mobile communication, that is, <NUM> mobile communication, is increasing and studies thereon are continuing.

In next-generation mobile communication, that is, <NUM> mobile communication, a data service having a minimum speed of <NUM> Gbps seems to be realized.

In <NUM> mobile communication, a turbo code, a polar code, a low density parity check (LDPC) code, etc. are considered as a channel coding method. Thereamong, the polar code is used by combining successive cancelation (SC) decoding and list decoding. However, in the list decoding, there is no method of excluding an erroneous decoding path through error correction before final decoding ends. Accordingly, the erroneous decoding path finally remains, thereby increasing an error probability and decreasing list gain.

The document ("<NPL>) discloses a multi-CRC aided SCL decoding scheme. In the document, for a multi-CRC polar code, an information block is described to be processed by one CRC encoder with check parity bits, and the information block is to be split into M sub-blocks.

<CIT> discloses a channel encoding and particularly relates to a polar code coding and decoding method with segmented cyclic redundancy check (Cyclic Redundancy Check, CRC) auxiliary check. In the document it is described that certain information bits are sacrificed to check polar codes to improve the decoding performance, assuming that the length of used CRC is K-k bits, the information is averagely divided into M segments by segmented CRC check, k/M bits of information and (K-k)/M bits of CRC check information constitute an information structure of each segment, the information bits are encoded and transmitted by a channel, finally, SCL decoding and check are carried out on the information received by a receiving end, and L maximum storage paths are available.

Accordingly, the disclosure of this specification is to solve the above-described problems.

According to the disclosure of this specification, it is possible to solve the above-described problems.

Specifically, according to the disclosure of this specification, it is possible to determine whether decoding is performed well before decoding is completed. More specifically, according to the disclosure of this specification, by allowing early termination of decoding upon determining that errors occur in decoding before decoding is completed, it is possible to reduce computational load due to blind decoding of a receiver and to reduce complexity and delay.

Technical terms used in this specification are used merely to illustrate specific embodiments, and it should be understood that they are not intended to limit the present disclosure. So long as not defined otherwise, all terms used herein including technical terms may have the same meaning as generally understood by an ordinary person skilled in the art to which the present disclosure pertains, and should not be construed in an excessively comprehensive manner or an extremely restricted manner. In addition, if a technical term used in the description of the present disclosure is an erroneous term that fails to clearly express the idea of the present disclosure, it should be replaced by a technical term that can be properly understood by those skilled in the art. In addition, general terms used in the description of the present disclosure should be construed according to definitions in dictionaries or according to context, and should not be construed in an excessively restrained manner.

A singular representation may include a plural representation unless context clearly indicates otherwise. It will be understood that the terms 'comprising', 'include', etc., when used in this specification, specify the presence of several components or several steps and part of the components or steps may not be included or additional components or steps may be further included.

For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element.

It will be understood that when an element is referred to as being "connected to" another element, the element can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly connected to" another element, there are no intervening elements present.

Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings in which the same reference numbers are used throughout this specification to refer to the same or like parts. In describing the present invention, a detailed description of known functions and configurations will be omitted when it may obscure the subject matter of the present invention. The accompanying drawings are used to help easily understood the technical idea of the present invention and it should be understood that the idea of the present invention is not limited by the accompanying drawings. The idea of the present invention should be construed to extend to any alterations, equivalents and substitutions besides the accompanying drawings.

The term base station used hereinafter refers to a fixed station communicating with a wireless device and may also be referred to as eNodeB (evolved-NodeB), eNB (evolved-NodeB), BTS (base transceiver system), access point, etc..

In addition, the term user equipment (UE) used hereinafter may be fixed or movable and may also be referred to as device, wireless device, terminal, mobile station (MS), user terminal (UT), subscriber station (SS), mobile terminal (MT), etc..

<FIG> is a view showing a wireless communication system.

Referring to <FIG>, the wireless communication system includes at least one base station (BS) <NUM>. Each base station <NUM> provides a communication service to specific geographical regions (generally, referred to as cells) 20a, 20b and 20c. The cell may be divided into a plurality of regions (referred to as sectors).

A UE generally belongs to one cell and a cell, to which the UE belongs, is referred to as a serving cell. A base station for providing a communication service to the serving cell is referred to as a serving BS. The wireless communication system is a cellular system and thus other cells are located adjacent to the serving cell. The other cells located adjacent to the serving cell are referred to as neighbor cells. BSs for providing communication services to the neighbor cells are referred to as neighbor BSs. The serving cell and the neighbor cell are determined based on the UE.

Hereinafter, downlink means communication from the BS <NUM> to the UE <NUM> and uplink means communication from the UE <NUM> to the BS <NUM>. On downlink, a transmitter may be a portion of the BS <NUM> and a receiver may be a portion of the UE <NUM>. On uplink, a transmitter may be a portion of the UE <NUM> and a receiver may be a portion of the BS <NUM>.

Hereinafter, an LTE system will be described in greater detail.

<FIG> is a view showing the structure of a radio frame according to FDD in 3GPP LTE.

Referring to <FIG>, the radio frame includes <NUM> subframes and one subframe includes two slots. The slots in the radio frame are numbered from <NUM> to <NUM>. A time required to transmit one subframe is referred to as a transmission time interval (TTI). The TTI may be a scheduling unit for data transmission. For example, the length of one radio frame may be <NUM>, the length of one subframe may be <NUM>, and the length of one slot may be <NUM>.

The structure of the radio frame is merely exemplary and the number of subframes included in the radio frame or the number of slots included in the subframe may be variously changed.

Meanwhile, one slot may include a plurality of orthogonal frequency division multiplexing (OFDM) symbols. The number of OFDM symbols included in one slot may vary according to cyclic prefix (CP).

One slot includes NRB resource blocks (RBs) in the frequency domain. For example, in an LTE system, the number of RBs, that is, NRB, may be any one of <NUM> to <NUM>.

The RB is a resource allocation unit and includes a plurality of subcarriers in one slot. For example, if one slot includes <NUM> OFDM symbols in the time domain and the RB includes <NUM> subcarriers in the frequency domain, one RB may include <NUM>×<NUM> resource elements (REs).

As mobile communication based on the <NUM> LTE/international mobile telecommunications (IMT) standard has been successfully commercialized, research into next-generation mobile communication (fifth-generation mobile communication) is ongoing. The fifth-generation mobile communication system aims at higher capacity than <NUM> LTE and can increase the density of mobile broadband users and support device to device (D2D), high stability and machine type communication (MTC). Research into and development of the <NUM> mobile communication system aim at lower latency and lower battery consumption than the <NUM> mobile communication system in order to better implement the Internet of things. For such <NUM> mobile communication, new radio access technology (New RAT or NR) may be proposed.

In NR, reception from a base station may use downlink subframes and transmission to the base station may use uplink subframes. This scheme is applicable to paired spectra and unpaired spectra. A pair of spectra means that two carrier spectra are included for downlink and uplink operation. For example, in a pair of spectra, one carrier may include a pair of a downlink band and an uplink band.

<FIG> is a view showing an example of a subframe type in NR.

The transmission time interval (TTI) shown in <FIG> may be referred to as a subframe or slot for NR (or new RAT). The subframe (or the slot) of <FIG> may be used in an NR (or new RAT) TDD system in order to minimize data transmission delay. As shown in <FIG>, the subframe (or the slot) includes <NUM> symbols, similarly to a current subframe. The front symbol of the subframe (or the slot) may be used for a DL control channel and the rear symbol of the subframe (or the slot) may be used for a UL control channel. The remaining symbols may be used for DL data transmission or UL data transmission. According to such a subframe (or slot) structure, downlink transmission and uplink transmission may be sequentially performed in one subframe (or slot). Accordingly, downlink data may be received in the subframe (or the slot) and uplink ACK/NACK may be transmitted in the subframe (or the slot). Such a subframe (or slot) structure may be referred to as a self-contained subframe (or slot). When such a subframe (or slot) structure is used, a time required to retransmit data which has been erroneously received can be reduced, thereby minimizing final data transmission latency. In the self-contained subframe (or slot) structure, a time gap may be necessary in a process of switching from a transmission mode to a reception mode or from a reception mode to a transmission mode. To this end, in the subframe structure, when switching from DL to UL, some OFDM symbols may be set as a guard period (GP).

Requirements of the <NUM> system include latency, peak data rate, error correction, etc. The <NUM> system, which will be used not only in a mobile communication system but also in ultra-high-resolution media streaming, the Internet of things, cloud computing, autonomous vehicles, etc., aims at performance much higher than the requirements of the LTE system in various areas.

The <NUM> system aims at <NUM> which is <NUM>/<NUM> the latency of the LTE system. Such short latency is an important indicator in an area directly related to human life, such as autonomous vehicles. The <NUM> system aims at a high transmission rate. The <NUM> system is expected to provide high-capacity high-speed communication such as high-quality media service streaming services with a maximum transmission rate which is <NUM> times that of the LTE system and a sensible transmission rate which is <NUM> to <NUM> times that of the LTE system. Error correction capability reduces a data retransmission rate, thereby improving latency and a data transfer rate.

As a <NUM> channel coding method, first, a turbo code, a polar code, a low density parity check (LDPC) code, etc. are considered.

First, the turbo code refers to a method of concatenating convolutional codes in parallel and applies different arrangements of the same sequence to two or more component codes. In the turbo code, a soft output iterative decoding method is used as a decoding method. Since the basic concept of turbo code decoding is to improve performance by exchanging information on each bit within a decoding period and using the information for next decoding, it is necessary to obtain soft output in the decoding process of the turbo code. Such a probabilistic iterative decoding method leads to excellent performance and speed.

Next, the LDPC code is based on the characteristics of an LDPC iterative decoding scheme, in which error correction capability per bit is improved but calculation complexity per bit is maintained, by increasing the length of the code. In addition, since the code may be designed such that decoding operation is performed in parallel, decoding of a long code can be performed at a high speed.

Finally, the polar code has low coding and low decoding complexity and is a first error correction code which has theoretically been proven to achieve a channel capacity in a general binary discrete memoryless symmetric channel. In contrast to the turbo code and the LDPC code using the iterative decoding process, the polar code uses a combination of successive cancelation (SC) decoding and list decoding. In addition, the polar code improves performance through pipelining, unlike the LDPC for improving performance through a parallel process.

<FIG> is a view showing the basic concept of a polar code and <FIG> is a view showing the structure of an SC decoder.

Referring to <FIG>, different inputs u<NUM> and u<NUM> undergo different channels and thus x1 and x2 are output. At this time, assume that input u<NUM> passes through a relatively good channel and input u<NUM> passes through a relatively bad channel. The channel means influence of an encoder. If the structure of <FIG> is repeated, input u<NUM> passing through the good channel gradually becomes better and input u<NUM> passing through the bad channel gradually becomes worse, thereby obtaining the structure shown in <FIG>. This is referred to as polarization.

The structure shown in <FIG> may be generated by a Kronocker product of a <NUM>×<NUM> kernel matrix. Accordingly, an encoder is always created in the form of the exponent of <NUM>.

In <FIG>, assume that the channel experienced by input u<NUM> is better than the channel experienced by input u<NUM>. That is, assume that the larger the index, the better the channel.

The polar code means a method of mapping data to a good channel and mapping a frozen bit (that is, known bit information such as <NUM>) to a bad channel, using polarization effects.

At this time, a code rate is determined by (the number of data bits)/(the number of data bits + the number of frozen bits).

<FIG> is a view showing the concept of a list decoding method.

As shown in <FIG>, the list decoding method means a method of maintaining L (L being greater than <NUM>) or more decoding candidates in a sequential decoding process such as trellis based or successive cancelation (SC) decoding and selecting a best decoding path by determining a measurement value such as a log likelihood ratio (LLR) when decoding of all bits is completed. Here, the decoding path means a path on which selection of each bit is stored in the sequential decoding process.

In the existing list decoding, after final decoding of all bits is completed, single cyclic redundancy check (CRC) was used for error correction to determine whether an error has occurred in all paths. Here, error correction in list decoding means that an erroneous decoding path of a plurality of lists is excluded.

In other words, in the existing list decoding, there is no method of excluding the erroneous decoding path through error correction before final decoding is completed. Accordingly, the erroneous decoding path finally remains, which may increase an error probability or decrease list gain. That is, in existing list decoding, a false alarm rate (FAR) increases. Here, the FAR refers to a probability that an incorrect signal is identified as a correct signal and is decoded, thereby passing CRC.

One disclosure of this specification proposes a multiple-cyclic redundancy check (CRC) structure in order to solve the above-described problem (the problem that erroneous decoding cannot be excluded through error correction using CRC before final decoding is completed in list decoding. Specifically, according to one disclosure of this specification, a method of using at least one of multiple CRCs for error correction before decoding is completed to improve decoding performance is proposed. According to this method, it is possible to determine whether an error occurs at an early stage while using list decoding. In addition, since a block error rate (BLER) can be improved, this method may be efficient.

Another disclosure of this specification proposes a method of using a single parity bit for the same purpose instead of CRC.

In this specification, for convenience of description, although a channel coding scheme using a polar code is described, the disclosure of this specification is generally applicable to channel coding schemes, to which list decoding is applicable.

As in a polar decoder, if channel coding using successive cancelation (SC) decoding is used, due to the properties of an SC decoder, an error may occur in a step of performing SC to generate error propagation, thereby deteriorating performance. In the case of successive cancelation list (SCL) decoding, error propagation may maintain an erroneous path as a list, thereby decreasing list gain. A method of applying multiple CRCs to perform multi-level CRC check in order to reduce influence of error propagation in a receiver using the SCL is proposed.

In the case of using M-level CRC, the following operations may be performed. First, data may be divided into M blocks. At this time, all the sizes of the blocks may be the same. Alternatively, the sizes of the blocks may be different from each other. The sizes of the data blocks may be set to reduce decoding error as much as possible. When data for different purposes are transmitted in one transmission block (TB), the sizes of the blocks may be set considering the size of each datum. Multiple CRCs are generated by the number of blocks and CRC generation rules may be equal or different with respect to all CRCs. When CRC generation rules are different, the sizes of the blocks matching CRCs may be different. The CRC generation rules may be controlled considering tradeoff between error correction and error detection performance and overhead size. Examples thereof will be described with reference to <FIG>.

<FIG> is a view showing non-claimed examples and the claimed embodiment of generating multiple CRCs when one TB is divided into two data blocks.

<FIG> shows a non-claimed example of calculating CRC by reflecting a corresponding data block. In this case, CRC is calculated by reflecting only the size of the data block directly associated therewith, thereby reducing complexity. In other words, if a transmission block (TB) is divided into n data blocks, CRC may be calculated with respect to each of n blocks. Therefore, (n-i)-th CRC may be calculated with respect to an (n-i)-th data block.

<FIG> shows the claimed embodiment of calculating CRC using a total sum of the data blocks. In <FIG>, CRC1 is generated by reflecting only Data <NUM> and CRC2 is generated by using Data <NUM> and Data <NUM>. In other words, if a TB is divided into n data blocks, (n-i)-th CRC may be generated with respect to a first data block to an (n-i)-th data block. This is characterized in that CRC calculated later has a value calculated by reflecting all data.

<FIG> shows a non-claimed example of calculating CRC by reflecting all blocks (data blocks and CRC blocks). This example is advantageous in that, although rules used to calculate CRCs or the lengths of CRCs are different, all preceding blocks affect rear CRC. In other words, if a TB is divided into n data blocks, the (n-i)-th CRC may be generated with respect to first to (n-i)-th data blocks and first to (n-i-l)-th CRCs. Here, the first CRC may be generated with respect to the first data block.

<FIG> shows a non-claimed example of calculating CRC by reflecting a data block directly associated therewith and previous CRC blocks thereof. In this case, since CRC is calculated by reflecting some of influence of the preceding data block and the size of the block necessary for simultaneous calculation is not large, it is possible to reduce complexity. In the above examples, for convenience, assume that one TB is divided into two data blocks. However, the above examples are applicable to the case where one TB is divided into two or more blocks and two or more multiple CRCs are used. In addition, although the sizes of the data blocks and the CRCs are the same for convenience in <FIG>, the above-described methods are applicable to the case where the sizes of the data blocks and the CRCs are different.

When applying multiple CRCs, the number of used data blocks and CRCs may be set according to various methods.

The number of multiple CRCs may be greater than the number of data blocks. For example, multiple CRCs respectively corresponding to data blocks may be present and one or more CRCs for checking all data blocks and multiple CRCs may be present. In this case, when the total number of data blocks is N, the number of multiple CRCs may be N+<NUM> or more.

In order to improve performance of list decoding, a single parity bit may be used instead of multiple CRCs. The reason why the single parity bit is used is as follows.

First, multiple CRCs have the following disadvantages. When CRC is generated by a plurality of polynomials, an additional J-bit CRC polynomial is necessary for distinguishment from the same CRC as the purpose used in the existing LTE and thus a calculation equation becomes complicated. In contrast, when CRC is generated by one polynomial, permutation operation of a CRC generation matrix is necessary to maintain correlation between data and CRC. Therefore, complexity of multiple CRCs may be higher than that of the single parity bit always having the same generation equation (without an additional calculation process). In addition, the CRC generation process has a disadvantage in that computational load is larger than that of a process of generating a single parity bit. Similarly, a process of checking CRC has a disadvantage in that computational load is larger than that of a process of checking a single parity bit.

In contrast, there is an advantage that the single parity bit may always be generated regardless of the position where the parity bit is added. In addition, there is an advantage that computational load is small in the process of generating or checking the parity bit.

The single parity bit added to the data block according to this disclosure may be used to prevent error propagation due to selection of the wrong list, similarly to the above-described multiple CRCs. A method of using the single parity bit may have lower error detection capability than the method of using multiple CRCs but may relatively reduce overhead.

In list decoding, the single parity bit may be used to check whether decoding of one or more data blocks is correct to maintain only a correct path. For example, in a list decoding operation for storing L paths as a list, it is possible to improve reliability of the list by determining whether an error occurs in data through XOR operation of all bits of a specific data block and the single parity bit and including only the correct paths in a candidate path.

A plurality of single parity bits may be located among a plurality of data blocks, into which one TB is divided. Multiple single parity bits may be generated as shown in <FIG>.

<FIG> is a view showing an example of generating multiple single parity bits when one TB is divided into two data blocks.

Although an example of dividing one TB into two data blocks is used for convenience of description in <FIG>, the description may be generally used for a plurality of single parity bits, e.g., two or more single parity bits. <FIG> shows an example of generating single parity bits by reflecting only a portion corresponding to each of two data blocks. <FIG> shows an example of generating single parity bits by reflecting influence of all preceding data blocks.

When the single parity bits are applied, the numbers of used data blocks and single parity bits may be determined using various methods.

An example of a method of using a single parity bit according to the TBS when two single parity bits are used is shown in <FIG>.

The number of single parity bits may be greater than the number of data blocks. For example, one single parity bit corresponding to each data block may be present and one or more single parity bits for checking all data blocks and the single parity bits may be present. In this case, when the total number of data blocks is N, the number of single parity bits may be equal to or greater than N+<NUM>.

The single parity bit and the multiple CRCs may be independently used and a combination of two technologies may be applied. When a combination of two technologies is used, the single parity bit is used in the middle of the data blocks and CRCs may be used in the last part of the data blocks. This will be described with reference to <FIG>.

<FIG> is a view showing an example of using a combination of a single parity bit and multiple CRCs.

As can be seen from <FIG>, when one TB is divided into two data blocks, the single parity bit may be generated with respect to the part corresponding to each data block. That is, a single parity bit SPB <NUM> may be generated with respect to Data <NUM> and a single parity bit SPB2 may be generated with respect to Data <NUM>. CRC may be added to the last part. The CRC of the last part may be used for error detection or error correction as described below with reference to <FIG>.

In this chapter, a method of enhancing decoding performance using multiple CRCs and a single parity bit in a list decoding process will be described. In the following description, error correction operation is a process of excluding an erroneous decoding path from among a plurality of lists and one or more decoding paths may be selected regardless of reliability of the decoding path. If errors are detected in all decoding paths of the list in the error correction process, early termination in which the decoding process is stopped is performed. In the following description, error detection operation is a process of checking errors with respect to one decoding path having highest reliability among a plurality of lists. When an error occurs in a corresponding path, a receiver does not perform error checking and determines that decoding fails, even when there is another decoding path in the list. At this time, a log likelihood ratio (LLR) value may be used as reliability. The LLR value may be obtained in a process of performing decoding and is changed according to the decoding path.

In this chapter, a method of tracking and erasing erroneous decoding paths before decoding of all bits is completed in the list decoding process will be described.

Since there is no method of performing error correction with respect to the erroneous decoding path before final decoding is completed in the existing list decoding, the corresponding decoding path may increase error probability or decrease list gain in a process of selecting a final decoding path.

In order to overcome such disadvantages, in this chapter, a method of checking reliability of the list in the middle of the decoding process through the methods of using multiple CRCs, the single parity bit or a combination thereof is proposed. Although multiple CRCs are used for convenience in this chapter, the single parity bit may be used or the multiple CRCs and the single parity bit may be simultaneously used.

<FIG> is a view showing an example of a list decoding process, and <FIG> is a flowchart illustrating the process shown in <FIG>.

First, in order to realize the proposal, assume that a transmission side and a reception side accurately know the positions of multiple CRCs. This may be estimated through the predetermined sizes of the data blocks and the multiple CRCs. If there is a plurality of predetermined values, it is possible to provide both the transmission side and the reception side with the sizes of used data blocks and multiple CRCs through exchange of information such as a control signal.

As shown in <FIG>, the reception side sequentially performs decoding of the data blocks and multiple CRCs (S1201 and S1203) and determines whether an error occurs in multiple paths through CRC check at the position of the CRC block for error correction (S1205). For example, if there are N CRC blocks for error correction, error path checking is performed N times. In each error detection step using multiple CRCs, paths on which errors occur are erased from the list and only paths on which errors do not occur as the CRC checking result are left in the list as surviving paths (S1207) and are used for the decoding step. This process is performed with respect to all data blocks and multiple CRC blocks and, when decoding and CRC checking of all bits are completed, a final decoding path is determined using a measurement value such as LLR (S1209).

Multiple CRCs may be used for error correction to determine whether an error occurs on each path of list decoding and increasing reliability of the list or may be used for error detection to determine whether an error occurs in bits which are determined as a decoding path and are decoded.

<FIG> is a view showing an example of using multiple CRCs.

As shown in <FIG>, if there are N data blocks and N+<NUM> multiple CRCs, N multiple CRCs may be used for error correction of each data block and (N+<NUM>)-th CRC may be used for error detection. For example, in <FIG>, second CRC may be used for error correction of a second data block. In this case, a method of using up to an N-th multiple-CRC block to select a decoding path having a highest measurement value such as LLR through the list decoding process and using a resultantly derived decoding bit for error detection using an (N+<NUM>)-th multiple-CRC is applicable. Although last CRC performing error check with respect to all data blocks is described in <FIG>, a period in which error check is performed may be changed according to the CRC generation method.

The (N+<NUM>)-th multiple-CRC may be used for error detection, but may be used for error correction according to the situation of the reception side as shown in <FIG>. In this case, in a list decoder using L lists, if it is assumed that M(≤L) paths, to which error correction is applied after the N-th multiple-CRC are detected, a method of determining M'(≤M) paths again using (N+<NUM>)-th multiple-CRC is applicable. As shown in <FIG>, when CRC used for error detection and CRC used for list decoding are successively arranged in the last part, the decoding order may be determined according to the generation order of CRC. This will be described with reference to <FIG>.

<FIG> is a view showing an example of the encoding and decoding order of multiple CRCs.

As shown in <FIG>, for example, if CRC which reflects all data is CRC block <NUM> and CRC which reflects data and CRC block <NUM> is CRC block <NUM>, the CRC encoding order is from CRC block <NUM> to CRC block <NUM> and the CRC decoding order is from CRC block <NUM> to CRC block <NUM>. At this time, as the purpose of each CRC block, CRC block <NUM> may be used for error detection and CRC block <NUM> may be used for list decoding, in order to check the influence of an error, which may occur in CRC block <NUM>, in CRC block <NUM> once in a first CRC check step. If CRC block <NUM> is first checked and then CRC block <NUM> is checked, a bit error, which may occur in CRC block <NUM>, cannot be checked in a process of checking CRC block <NUM>.

Specifically, referring to <FIG>, the encoding order may be determined to generate CRC1 for data and then to reflect the data and CRC1 to generate CRC2. In contrast, referring to <FIG>, the decoding order may be determined to use CRC2 with respect to the block including all data, CRC1 and CRC2 and then to use CRC1 with respect to the block including the data and CRC1. At this time, CRC1 may be used for error detection and CRC2 may be used for list check.

If the above-described multiple CRCs (and/or the single parity bit) are used, a method of mapping data and CRC bits (and/or single parity bits) in an encoding process may be determined by reliability from the viewpoint of the input bit of an encoder. For example, in the case of a polar code, if the total bit number of the data and the CRC bits (and/or the single parity bits) is K, the K bits may be sequentially arranged in K bits having highest reliability from the viewpoint of the input bit. If K reliable bit positions are determined, the arrangement order of the data and the CRC bits (and/or the single parity bits) may be determined in consideration of the decoding order shown in <FIG>. Here, for the sake of understanding, the reason why the reliability of each input bit of the polar code is different is as follows. First, as described above, the polarization effects of the polar code are changed according to input bit. Accordingly, there may be bits having higher reliability and bits having relatively low reliability among input bits which are input as data. Generally, in the structure shown in <FIG>, as the index of the input bit is increased, reliability is increased.

<FIG> is a view showing an example of arranging data bits and CRC bits (and/or single parity bits).

A frozen bit shown in <FIG> means a bit which is not used as data and CRC bit (and/or single parity bit) when the total size of the encoder of a polar code is N, and is filled with information known to the transmission side and the reception side. In <FIG>, the data block and CRC bits (and/or the single parity bits) may be generated as described in Chapters I and II.

When the data block and the CRC block (and/or the single parity bit) are generated as described in Chapters I and II, a relationship between the data block and the CRC block (and/or the single parity bit) may consider reliability from the viewpoint of the encoder input bits. For example, in the case of the polar code, the reliabilities of the encoder input bits may have different values and some input bits may have a relatively higher error probability than the other input bits. In order to consider a difference in reliability, the CRC bit (and/or the single parity bit) may appear at a high frequency at positions earlier in the decoding order. That is, since a probability that an error occurs is low in the case of the input bits having high reliability, CRC may be added with low density. In contrast, since a probability that an error occurs is high in the case of input bits having low reliability, CRC may be added with high density. This will be described with reference to <FIG>.

<FIG> is a view showing an example in which the sizes of successive data blocks distinguishable according to the position of CRC or a single parity bit differ.

As shown in <FIG>, the sizes of successive data blocks distinguishable according to the position of the CRC or single parity bit may differ from each other according to the decoding order. That is, in the example of <FIG>, the earlier the decoding order, the shorter the data block, after which the CRC or the single parity bit appears. This serves to increase error detection capability with respect to input bits with relatively low reliability. At this time, the size of each data block may be defined by a ratio relative to each other.

In a control channel such as a physical downlink control channel (PDCCH), scrambling of CRC may be used with a UE identity. Similarly, even in the multiple-CRC scheme proposed by the present invention, a UE may be identified through CRC. If control information such as a PDCCH is transmitted using CRC alone and the UE is identified through CRC, a false alarm rate (FAR) in which a decoder using list decoding may misjudge a signal thereof even when it is not a signal thereof is increased. However, as described above, if the multiple-CRC scheme is used and at least one CRC is used for error detection, the FAR of the UE may be reduced, thereby relatively increasing a probability that the UE identity is accurately distinguished. Accordingly, for the purpose of distinguishing the UE identity in the control channel, a multiple-CRC structure is more advantageous than an existing single CRC structure considering the UE using list decoding.

The scrambling method which may be used in a UE identity distinguishing method through scrambling of multiple CRCs proposed in this chapter may follow the following options.

In Option <NUM>, scrambling is not applied to CRC used for list decoding but is applied to only CRC used for error detection. For example, when scrambling of CRC is used to represent an N-bit RNTI in N-bit CRC, a scrambling code having a length of N bits is used and applicable to CRC used for error detection. Since this is not so different from the method used in existing LTE, if the length of CRC used for error detection is equal to that of LTE, this method is advantageous from the viewpoint of backward compatibility of NR. In Option <NUM>, one long scrambling is applied to the total length of multiple CRCs. For example, in order to represent an N-bit RNTI, an N-bit scrambling code may be generated, may be divided by a length of N/<NUM> bits, and may be divisionally used in two CRCs each having a length of N/<NUM> bits. In addition, this method may be extended to a method of dividing multiple CRCs into smaller groups and applying scrambling in group units. This method is advantageous in that it is possible to prevent the capability of distinguishing the UE identity from being reduced due to reduction in the length of one CRC by introduction of multiple CRCs. In Option <NUM>, the same scrambling is applied to multiple CRCs. For example, when CRC scrambling is used to represent an N-bit RNTI, an N-bit scrambling code is generated and is equally applied to each CRC having a length of N bits. This method is advantageous in that influence of scrambling is checked plural times to check the UE identity plural times, thereby reducing the FAR. In Option <NUM>, different scrambling is applied to CRCs. In this method, some CRCs may share the same scrambling. The method of applying different scrambling may serve to represent one UE identity in various manners. For example, in order to represent an N-bit RNTI, if an N-bit scrambling code is used and N-bit CRC has M blocks, M different scrambling codes for representing the same RNTI may be generated and respectively used for CRCs. This is advantageous in that the same UE identity is represented several times to reduce the influence of the FAR. Alternatively, one UE identity may be represented by a combination of a plurality of scrambling codes. For example, if two CRCs, each having a length of N/<NUM>, are used to represent an N-bit RNTI, the N-bit RNTI may be divided into two RNTI parts having a length of N/<NUM> bits and a scrambling code corresponding to the RNTI part having the length of N/<NUM> bits may be generated and applied to CRC having a length of N/<NUM> bits. This may serve to compensate for a short length when the length of the RNTI and the length of the CRC block do not match. Alternatively, two or more different UE identities may be represented. For example, if there are an N-bit RNTI for the purpose of A and an M-bit RNTI for the purpose of B, independent scrambling codes corresponding to the N-bit length and the M-bit length may be generated and respectively used for CRC having a length of N bits and CRC having a length of M bits. At this time, N and M are arbitrary integers, which may be equal to or different from each other. This may allow for one UE to distinguish the control channel for two or more purposes.

The embodiments of the present invention can be implemented by a variety of means, for example, hardware, firmware, software, or a combination thereof. More specifically, the description will be made with reference to the drawings.

<FIG> is a block diagram showing a wireless communication system implemented by this disclosure.

A base station <NUM> includes a processor <NUM>, a memory <NUM> and a radio frequency (RF) unit <NUM>. The memory <NUM> is connected to the processor <NUM> to store a variety of information for driving the processor <NUM>. The RF unit <NUM> is connected to the processor <NUM> to transmit and/or receive a radio signal. The processor <NUM> implements the proposed function, process and/or method. In the above-described embodiment, operation of the base station may be implemented by the processor <NUM>.

The UE <NUM> includes a processor <NUM>, a memory <NUM> and an RF unit <NUM>. The memory <NUM> is connected to the processor <NUM> to store a variety of information for driving the processor <NUM>. The RF unit <NUM> is connected to the processor <NUM> to transmit and/or receive a radio signal. The processor <NUM> implements the proposed function, process and/or method.

Claim 1:
A method of encoding an information sequence at a transmitting device, the method comprising:
generating the information sequence for channel encoding based on a polar code; and
performing, by an encoder, channel encoding for the information sequence based on the polar code to produce an encoded information sequence,
wherein the information sequence includes at least a first data block, a first parity block, a second data block, and a second parity block,
wherein the first parity block is subsequent to the first data block in the information sequence, the second data block is subsequent to the first parity block, and the second parity block is subsequent to the second data block, and
characterised in that the second parity block is generated based on preceding data blocks only that include the first and second data blocks, and not based on any following data block.