JP2011504038A - Transport block size determination method and signal transmission method using the same - Google Patents

Abstract

A method for determining a transport block size and a signal transmission method using the same are disclosed. In this signal transmission method, if a transport block size combination is determined in advance to form a transport block size combination, it is possible to prevent the insertion of an arbitrary dummy bit in consideration of the limit of the input bit length of the encoder at the time of encoding. When a CRC is attached to a transport block and the transport block is divided into a plurality of code blocks, this signal transmission method considers the length of the transport block in consideration of the length of the CRC attached to each code block. Can be set.
[Selection] Figure 3

Description

  The present invention relates to a method and apparatus for efficiently determining the size of a data block or transport block in a wireless communication system, and a method for transmitting a signal using the method.

  Generally, in a communication system, the transmission side of the communication system encodes transmission information using a forward error correction code, and transmits the encoded information to the reception side of the communication system. On the side, errors caused by the channel in the received information can be corrected. The reception side demodulates the reception signal and decodes the error correction code to restore the transmission information transmitted from the transmission side. In this decoding process, the received signal error caused by the channel can be corrected.

  Although various types of error correction codes can be used, for convenience of explanation, a turbo code will be described below as an example of the forward error correction code. The turbo code includes a recursive systematic convolution encoder and an interleaver. When a turbo code is actually implemented, there is an interleaver for facilitating parallel decoding, and a QPP (quadratic polynomial permutation) interleaver can be used as an example of this interleaver. This QPP interleaver is known to maintain good throughput or performance only for specific data block sizes. In this case, the term “data block” means block unit data encoded by the encoder. When block unit data transferred from the upper layer to the physical layer is encoded without segmentation described below, this data block can also be referred to as a transport block (TB). On the other hand, considering the segmentation of the transport block to be encoded, this data block matches the “code block”.

  In general, the turbo code performance increases as the data block size increases. In an actual communication system, a data block of a certain size or more is divided into a plurality of data blocks having a small size and encoded for convenience in actual implementation. A divided data block having a small size is called a code block. In general, these code blocks have the same size, but one code block among a plurality of code blocks may have different sizes due to the limitation of the QPP interleaver size. A data block having a small size is transmitted through a radio (RF) channel after an error correction coding process in units of code blocks having a predetermined interleaver size. In this case, the data blocks are interleaved in order to reduce the influence of burst errors that occur in the process of transmitting the data blocks on the radio channel. The interleaved data block is mapped to an actual radio resource and transmitted.

  Since the amount of radio resources used in the actual transmission process is constant, rate matching must be performed on the encoded code block. In general, the rate matching process is performed by puncturing or repetition. For example, rate matching can also be performed in units of coded code blocks, such as 3GPP WCDMA. As another example, the systematic and parity portions of the encoded code block are separated from each other. The systematic part and the parity part can be rate matched together, or the systemmatic part and the parity part can be rate matched independently.

  FIG. 1 is a conceptual diagram illustrating the basic operation of a turbo encoder.

  As shown in FIG. 1, when the turbo encoder receives one code block, the received code block is divided into a systematic part (S) and a parity part (P1 and P2). The systematic part (S) and the parity part (P1 and P2) pass through the respective sub-block interleaver. Therefore, the systematic part (S) and the parity part (P1 and P2) are interleaved by different sub-block interleavers, and the interleaved result is stored in a circular buffer.

  As can be seen from FIG. 1, the systematic part and the parity part of the code block can be separated from each other, and rate matching is performed on each separated part. However, the example of FIG. 1 is for illustrating the present invention, and the idea and spirit of the present invention are not limited to this example, and can be applied to other examples. For convenience of explanation, the code rate is 1/3.

  Various transport block sizes can be defined depending on the service type of the upper layer, but it is preferable to quantize the transport block size in order to efficiently perform signaling of various transport block sizes. In the quantization process, dummy bits can be added to the source data block in order to adjust the source data block transferred from the upper layer to the data block size of the physical layer. In this quantization process, it is preferable to minimize the amount of added dummy bits.

  In order to achieve these and other benefits, and in accordance with the objectives of the present invention, a signal transmission method and apparatus is provided, as embodied and broadly described herein, which has a specific size. Determining the number of code blocks used to transmit the transport blocks having and mapping the transport blocks to code blocks corresponding to the determined number; a cyclic redundancy check for each of the code blocks redundancy check: CRC); encoding each code block with CRC by a turbo encoder including an internal interleaver; and transmitting the encoded code block; The specific size of the block is a preset transport block Corresponds to an arbitrary transport block size in the combination, and an arbitrary transport block size in the preset transport block size combination is a code block mapped to a transport block having a specific size. The sum of the length of any one of the code blocks and the CRC length attached to the one code block is set in advance to be the same as the block size of the internal interleaver.

  The block size of the internal interleaver of the turbo encoder can be determined in advance as a combination of predetermined bit lengths.

  Under the above assumption, if the number of code blocks used to transmit a transport block is 1, the specific transport block size is any one of the predetermined transport block sizes, CRC It can be any one of the preset transport block size combinations that correspond to the sum of the length and the block size of the internal interleaver.

  Under the same assumption, if the number of code blocks used to transmit a transport block is two or more, the transport block is divided into two or more code blocks having the same length and two or more. Can be mapped to a code block.

  The above operation can be generalized as the following equation.

If the size of the transport block is N, the number of code blocks used to transmit the transport block is M, the length of each of the M code blocks is N _C , and the CRC length is L, the specific transport The block size N can satisfy N = M * N _C -L, and the specific transport block size is the block size of the internal interleaver where the value of N _C + L is predetermined as a combination of the predetermined bit length It can be any one of the preset transport block size combinations that correspond to the above.

  Specifically, the block size of the internal interleaver of the turbo encoder can be preset as a “K” value according to index (i) in Table 1 below.

  Under this assumption, if the number of code blocks used to transmit a transport block is 1, the specific transport block size is the K value shown in Table 1 as an arbitrary transport block size. And the transport block size combination corresponding to the sum of the CRC length.

  The above operation can be generalized by the following equation.

If the size of the transport block is N, the number of code blocks used to transmit the transport block is M, the length of each of the M code blocks is N _C , and the CRC length is L, the specific transport The block size N can satisfy N = M * N _C -L, and the specific transport block size is a combination of transport block size combinations in which the value of N _C + L corresponds to the K value in Table 1. Can be one of them.

  The specific size N of the transport block can be set to a length selected from the combinations shown in Table 2 below according to the number M of code blocks that can be used to transmit the transport block.

  In this method, information on a modulation and coding scheme (MCS) and an available resource region size is received from a receiving side, and based on the received information, a specific transport is selected from among preset transport block size combinations. The method may further include determining a port block size.

  When the transport block size based on the received information is not included in the preset transport block size combination, the specific transport block size is selected from the preset transport block size combinations based on the received information. Set to the maximum transport block size that does not exceed the size of the port block, among the preset transport block size combinations, the minimum transport block size that exceeds the transport block size based on the received information, or set in advance Among the transport block size combinations that have been made, the transport block size having the smallest difference from the transport block size based on the received information can be obtained.

In another embodiment of the present invention, attaching a first CRC of length L to a transport block of length N; and transporting the transport block with the first CRC to M having a length of N _C Dividing each of the divided M code blocks with a second CRC of size L; and the M code blocks with the second CRC attached to each of the divided M code blocks; Encoding using a turbo encoder with an inner interleaver; transmitting the encoded M code blocks, wherein the size N of the transport block is N = M * N Has a size that satisfies _C -L (where N, N _C , M, and L are natural numbers), and the N _C + L has one of the block sizes of the internal interleaver of the turbo encoder Set as To provide a signal transmission method according to claim Rukoto.

  In yet another embodiment of the present invention, a transport block having a length of N is mapped to one or more code blocks; a turbo encoder having an internal interleaver for the one or more code blocks; Transporting the encoded code block, wherein the transport block size N includes all or part of the values listed in Table 3 below: Provided is a signal transmission method (where N is a natural number) that is a transport block size selected from among the block size combinations.

  According to each embodiment of the present invention as described above, when a transport block received from an upper layer is divided into code blocks and encoded by a turbo encoder, dummy bits based on an input bit length of an internal interleaver of the turbo encoder Can be avoided and signals can be transmitted efficiently.

  Together with the specification serving to explain the principles of the invention, the accompanying drawings included to provide a further understanding of the invention illustrate embodiments of the invention.

It is a conceptual diagram explaining the basic operation | movement of the turbo encoder by this invention. 3 is a conceptual diagram illustrating a method of dividing a long transport block into a plurality of short transport blocks and attaching CRC to the short transport block in the 3GPP system according to the present invention. FIG. 3 is a conceptual diagram illustrating a method of dividing a long transport block into a plurality of short transport blocks and attaching CRC to the short transport block in the 3GPP system according to the present invention. FIG. It is a figure explaining the setting principle of the transport block size by one Example of this invention. It is a figure which shows an example of the resource structure by this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, throughout the present specification, the same constituent elements will be described using the same reference numerals. The terms used in the present invention are selected from general terms that are widely used as much as possible. However, in some cases, there are terms arbitrarily selected by the applicant. Since the meaning is described in detail in the explanation part of the invention, it should be clarified that the present invention should be grasped not as a simple term name but as a meaning of the term.

  For the convenience of explanation and understanding of the invention, the following detailed description discloses various embodiments and variations of the invention. In some cases, in order to avoid obscuring the concept of the present invention, well-known structures and devices are omitted as appropriate, or illustrated in a block diagram format centering on the core functions of each structure and device. Further, throughout the present specification, the same constituent elements will be described with the same reference numerals.

  As described above, the internal interleaver of the turbo code is known to exhibit excellent performance only for a specific data block size. When the data block size is a certain size or more, the transport block or data block is divided into a plurality of code blocks. This process is called segmentation. Due to the limitations on the interleaver size as described above, the transport block or data block may not be divided into code blocks of the same size.

  However, for the downlink, it is preferable that the transport block or data block is divided into code blocks of the same size, since the channel quality indicator must be applied to all of the code blocks divided from the data block. If the data block size or the divided code block size is different from the internal interleaver size of the turbo code, dummy bits are inserted. In this case, however, transmission efficiency decreases. In order to solve this problem, a segmentation process that does not require dummy bits is preferable.

  For the operation described above, it is necessary to consider the block size of the internal interleaver of the turbo encoder, which is directly responsible for inserting dummy bits. To perform channel coding, a CRC is attached to a transport block or a code block divided from the transport block and at the same time the length of each data block is converted to another length, thus for channel coding. It is necessary to consider.

  First, the CRC adding process described above will be specifically described.

  A CRC for detecting an error is attached to a transport block received from an upper layer. For convenience of implementation, a CRC can be attached to each of the divided code blocks.

  2 and 3 are conceptual diagrams illustrating a method of dividing a long transport block into a plurality of short transport blocks and attaching CRC to the short transport blocks in the 3GPP system according to the present invention.

  The 3GPP system divides a long transport block (TB) into a plurality of short code blocks (CB), encodes the short code block, collects the encoded short code blocks, and collects the collected short code blocks. Is transmitted. This operation in the 3GPP system will be described in detail with reference to FIG.

  Referring to FIG. 2, a long transport block has a CRC, that is, a CRC is added to the transport block (S101). Thereafter, the long transport block with CRC is divided into a plurality of short code blocks (S102). As indicated by reference numerals 201 to 203 in FIG. 3, the CRC is attached to a long transport block, and the transport block to which the CRC is attached is divided into a plurality of code blocks. However, if the length of the transport block received from the upper layer is less than the predetermined length that can be configured by one code block, that is, the maximum length of the internal interleaver of the turbo encoder, the transport block segmentation Can be omitted. In this case, the process of attaching CB CRC can also be omitted.

  On the other hand, CRC is attached to each short code block. That is, a CRC attaching process is performed for each code block (S103). Specifically, as indicated by reference numeral 204 in FIG. 3, each code block includes a CRC.

  Each code block with a CRC is applied to the channel encoder, and channel coding is performed on the code block (S104). Thereafter, each code block is transmitted to the receiving side through rate matching (S105), code block concatenation and channel interleaving process (S106).

  Therefore, according to the following embodiment, a method for determining the size of a transport block in consideration of a two-stage CRC attachment process is proposed. When the size of the transport block is smaller than a predetermined size (such as the maximum internal interleaver size) and this transport block is mapped to one code block, the embodiment of the present invention only applies one CRC. A method for setting the transport block size in consideration is provided.

  Under the above assumption, a method for mapping a transport block to one code block will be described. In order to eliminate the need for the prior art to add dummy bits when a transport block is mapped to one codeword, an embodiment of the present invention provides a transport block size (N) and one CRC length. We propose to make the sum equal to the block size of the internal interleaver of the turbo encoder. Table 1 below shows combinations of block sizes of the internal interleaver of the turbo encoder.

  Therefore, as shown in Table 1, when a transport block is mapped to one code block, the transport block subtracts the CRC length attached to the transport block from the block size (K) of the internal interleaver. It is preferable to have a specific length. If the length of the CRC attached to the transport block is 24 bits, the transport block size (N) when the transport block is mapped to one code block can be K-24. That is, in this embodiment, the transport block size can be selected from the combinations shown in Table 4 below.

  Meanwhile, in the following, a method of dividing one transport block into two or more code blocks and performing a mapping process on the divided code blocks will be described in detail.

  When one transport block is divided into two or more code blocks, as shown in FIGS. 2 and 3, CRC for transport block is attached to the transport block, and each CRC for code block is divided. Attached to each code block. Under these assumptions, in order to eliminate the addition of dummy bits, the sum of the size of an arbitrary divided code block and the size of the CRC attached to the corresponding code block is as shown in Table 1. The input bit size of the internal interleaver is preferably the same.

  In the embodiment of the present invention, the divided codewords have the same size. The difference in code block size due to transport block segmentation is due to the size limitation of the internal interleaver of the turbo encoder. As described in the present embodiment, when the transport block size is set in advance in consideration of the size of the internal interleaver of the turbo encoder, each code block does not need to have a different size.

  A method for setting the transport block size according to the present embodiment under the above assumption will be described in detail below.

  FIG. 4 is a diagram for explaining the principle of setting the transport block size according to an embodiment of the present invention.

First, it is assumed that a CRC having a size L is added to a transport block (TB) having a size N. If the CRC-attached transport block (TB) size is longer than the maximum length of the internal interleaver, the transport block is divided into a plurality of code blocks (CB). As can be seen from FIG. 4, the transport block (TB) size is divided into _M code blocks (CB _{1 to} CB _M ) having the same N _C bit length.

  On the other hand, a CRC having a size L is attached to each of the M code blocks.

  As described above, when the divided code blocks have the same length and the two attached CRC lengths are considered, the transport block size N can be expressed by Equation 1 below.

  If a 24-bit CRC is used, the above Equation 1 can be expressed by another equation such as N = M * Nc-24.

  Since each of the divided code blocks includes a CRC, the code block with CRC is input to the internal interleaver of the turbo encoder. Therefore, as shown in FIG. 4, the length of the code block with CRC is the same as the block size of the internal interleaver shown in Table 1, as shown in Equation 2.

  Based on the above description, this embodiment proposes a method using the following transport block size shown in Table 2 below. Table 2 below represents various cases illustrating the relationship between a single transport block and up to 25 code blocks mapped to this single transport block.

  Table 2 shows up to the case where the above Equation 1 and Equation 2 are satisfied and one transport block is divided into 25 code blocks. Within the range satisfying Equation 1 and Equation 2, those skilled in the art can sufficiently estimate the additional transport block (TB) size from the values shown in Table 2.

  Since signal transmission is performed according to the above-described embodiment of the present invention, the addition of dummy bits due to the block size limitation of the turbo encoder can be removed, and the system performance or throughput can be improved.

  On the other hand, considering not only the case where the transport block is mapped to one code block but also the case where the transport block is divided into two or more code blocks, the available transport block sizes are shown in Table 3. be able to.

When implementing the above method, if the terminal recognizes that the transport block length with CRC is larger than the maximum interleaver block size, the terminal determines the number of code blocks from the lookup table, or Based on this, the number of code blocks can be calculated. This calculation includes calculating the number of code blocks based on the following equation.

  The signal transmission method and apparatus according to the present invention allows the transport block to have a predetermined length corresponding to any one of the various values shown in Table 3. Table 3 shows the available transport block (TB) sizes that eliminate the need to insert dummy bits into the signal. According to the signal transmission method, instead of using all the values in Table 3, a subset of Table 3 can be shared between the transmitting side and the receiving side in consideration of signaling overhead and the like.

  On the other hand, in order to inform the receiving side of the transport block size, the transmitting side can represent the transport block size by a combination of modulation and decoding scheme (MCS) and the allocated resource size. The scheduler determines the MCS according to the channel quality indicator transmitted from the receiving side. The size of the allocated resource is determined in consideration of not only a resource for transmitting control information but also other resources for a reference signal for channel estimation.

  FIG. 5 is a diagram illustrating an example of a resource structure according to the present invention.

  Referring to FIG. 5, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. When the resource structure of FIG. 5 is used, if a resource for transmitting control information corresponds to three symbols and two transmission antennas are used, one resource block (RB) is used for data transmission. 120 resource elements (RE) that can be used.

  In this case, if the modulation rate is 64QAM, the coding rate is 0.6504, and the number of allocated resource blocks (RBs) is 10, the size of the transmittable data block is 4658 bits. These 4658 bits exist between 4608 bits and 4672 bits in Table 1. When the size of a transmittable data block is set to 4608 bits or 4672 bits, the data block size can be determined by various modulation and coding rates and allocated resource sizes.

  As described in the above example, if the actually transmittable data block size is different from the supportable data block size, the actually transmittable data block size is determined by the following rules i) to iii). be able to.

  A method of determining a data block size that can be supported at most that is not larger than a data block size that can be actually transmitted as a data block size that can be actually transmitted.

  A method of determining a minimum supportable data block size larger than a data block size that can be actually transmitted as a data block size that can be actually transmitted.

  A method of determining a supportable data block size having a smallest difference from a data block size that can be actually transmitted as a data block size that can be actually transmitted.

  In this case, if one transport block is transmitted through one code block, the data block can correspond to the transport block. If one transport block is transmitted through two or more code blocks, the data block can be regarded as a code block.

  Although the present invention has been described with reference to the preferred embodiments of the present invention, the present invention can be variously modified without departing from the spirit and scope of the present invention described in the appended claims. This is obvious to those with ordinary knowledge in the art. For example, the signal transmission method according to the present invention was disclosed based on the 3GPP LTE system, but has a block size limitation, and is also applicable to other communication systems using a predetermined combination of transport block sizes. Is possible.

  When the transport block received from the upper layer is divided into a plurality of code blocks and the code block is encoded by the turbo encoder, the signal transmission method according to the present invention is caused by the restriction on the block size of the internal interleaver of the turbo encoder. This eliminates the addition of dummy bits and allows signals to be transmitted efficiently.

Claims (25)

A method of transmitting data from a first device including a physical layer and an upper layer of the physical layer to a second device including an interleaver having a plurality of predetermined block sizes,
Receiving a transport block having a predetermined length from the upper layer of the physical layer at the physical layer;
Attaching a first CRC code having a first CRC code length to the received transport block to generate a transport block with CRC having a length larger than a maximum interleaver block size;
Dividing the transport block with CRC into a predetermined number of code blocks having a common length;
Each of the predetermined number of code blocks is attached with a corresponding second CRC code having a second CRC code length, and a code block with CRC having the same length as one of the plurality of predetermined block sizes is obtained. Generating stage,
Having a method.   The method of claim 1, wherein the maximum interleaver block size is 6144.   The method of claim 1, wherein the first and second CRC code lengths are 24.   The method of claim 1, wherein the predetermined number of code blocks is identical to a value x, where x ≧ 25 ≧ x ≧ 2. The step of dividing the transport block with CRC into a predetermined number of code blocks having a common length includes:
Determining a length of the transport block with CRC larger than the maximum interleaver block size;
Selecting the predetermined number of code blocks from a lookup table;
The method of claim 1, comprising: The step of dividing the transport block with CRC into a predetermined number of code blocks having a common length includes:
Determining a length of a transport block with CRC larger than the maximum interleaver block size;
Calculating the predetermined number of code blocks based on the following equation:
The method of claim 1, comprising:

The method of claim 1, wherein one of the plurality of predetermined block sizes is the same as a value in the table below.

The predetermined length is N, the predetermined number of code blocks is M, the common length is N _C , the first and second CRC code lengths are L, and the predetermined length N The method of claim 1, wherein N = M * N _C -L. The predetermined number of code blocks is M, the predetermined length is N, and a set of M and N values is one of a set of values shown in the following table. the method of.

Channel coding the code block with CRC;
Rate matching the channel coded blocks;
Performing code block concatenation and channel interleaving on the rate-matched code blocks;
Transmitting the block concatenated and channel interleaved code blocks;
The method of claim 1, further comprising:   The method of claim 1, wherein the first device is a mobile terminal and the second device is a base station.   The method of claim 1, wherein the first device is a base station and the second device is a mobile terminal. A mobile terminal having a physical layer and an upper layer of the physical layer and configured to transmit data to an external device,
An interleaver having a plurality of predetermined block sizes;
In the physical layer, a transport block having a predetermined length is received from the higher layer of the physical layer, and a first CRC code having a first CRC code length is attached to the received transport block, A transport block with CRC having a length larger than the maximum interleaver block size is generated, the transport block with CRC is divided into a predetermined number of code blocks having a common length, and the predetermined number of code blocks A corresponding CRC code having a second CRC code length is attached to each of the code blocks to generate a code block with CRC having the same length as one of the plurality of predetermined block sizes. A processor;
A mobile terminal.   The mobile terminal according to claim 13, wherein the maximum interleaver block size is 6144.   The mobile terminal according to claim 13, wherein the first and second CRC code lengths are 24.   The mobile terminal according to claim 13, wherein the predetermined number of code blocks is the same as the value x, and x is 25 ≧ x ≧ 2.   The mobile terminal according to claim 13, wherein the processor determines a length of the transport block with CRC larger than the maximum interleaver block size, and selects the predetermined number of code blocks from a lookup table. The mobile terminal according to claim 13, wherein the processor determines the length of the transport block with CRC larger than the maximum interleaver block size, and calculates the number of code blocks based on the following equation.

The mobile terminal according to claim 13, wherein one of the plurality of predetermined block sizes is the same as a value in the following table.

The predetermined length is N, the predetermined number of code blocks is M, the common length is N _C , the first and second CRC code lengths are L, and the predetermined length N The mobile terminal according to claim 3, wherein N = M * N _C -L. The predetermined number of code blocks is M, the predetermined length is N, and a set of M and N values is one of a set of values shown in the following table. Mobile terminal.

  Channel coding the code block with CRC, rate matching the channel coded block, performing code block concatenation and channel interleaving on the rate matched code block, and transmitting the block concatenated and channel interleaved code block The mobile terminal according to claim 13, further comprising: A base station transmission device having a physical layer and an upper layer of the physical layer and configured to transmit data to a mobile terminal,
An interleaver having a plurality of predetermined block sizes;
The transport block having a predetermined length is received from the higher layer of the physical layer at the physical layer, and a first CRC code having a first CRC code length is attached to the received transport block, A transport block with CRC having a length larger than the maximum interleaver block size is generated, and the transport block with CRC is divided into a predetermined number of code blocks having a common length, and the predetermined number of code blocks A processor configured to generate a code block with CRC having the same length as one of the predetermined block sizes by attaching a corresponding second CRC code having a second CRC code length to each. When,
A base station transmitter. The predetermined number of code blocks is M, the predetermined length is N, and a set of M and N values is one of a set of values shown in the following table. Base station transmission device.

Determining the number of code blocks used to transmit a transport block having a specific size, and mapping the transport blocks to code blocks corresponding to the determined number;
Attaching a CRC to each of the code blocks;
Encoding each CRC code block with a turbo encoder including an inner interleaver;
Transmitting the encoded code block;
Including
The specific size of the transport block corresponds to an arbitrary transport block size in a preset transport block size combination,
An arbitrary transport block size in the preset transport block size combination includes a length of one code block in a code block mapped to a transport block having a specific size, and the one code A signal transmission method, wherein a sum of a CRC length attached to a block is set in advance to be equal to a block size of the internal interleaver.

Images