KR20100049179A - Method for transmitting data using harq - Google Patents

Abstract

PURPOSE: A method for transmitting data using an HARQ(Hybrid Automatic Repeat Request) is provided to efficiently obtain a coding gain of an IR(Incremental Redundancy) mode by giving a cyclic offset indicating a cycle point to retransmission data. CONSTITUTION: A first sub-packet which is a bit string of a code word is transmitted. According to the retransmission request for the code word, a second sub-packet comprising a bit string continuous on the first sub-packet is transmitted. The second sub packet is configured in bit string after cyclic offset that moves the cyclic point of a bit string included in retransmitted data. A turbo code is applied to a code word to be configured in at least one parity bit. The cyclic offset includes the range of the structured bit.

Description

Method for transmitting data using HARQ {Method for transmitting data using HARQ}

The present invention relates to wireless communication, and more particularly, to a data transmission method using HARQ.

Error compensation techniques for securing communication reliability include a forward error correction (FEC) scheme and an automatic repeat request (ARQ) scheme. In the FEC scheme, an error at the receiving end is corrected by adding an extra error correction code to the information bits. In the ARQ scheme, errors are corrected through data retransmission, and there are a stop and wait (SAW), a go-back-N (GBN), and a selective repeat (SR) scheme. The SAW method is a method of transmitting the next frame after checking whether the transmitted frame is correctly received. The GBN method transmits N consecutive frames and retransmits all frames transmitted after the frame in which an error occurs if transmission is not successful. The SR method selectively retransmits only a frame in which an error occurs.

The FEC method has a short time delay and does not require information to be exchanged between the transmitter and the receiver, but has a disadvantage in that the system efficiency is poor in a good channel environment. ARQ method can improve the transmission reliability, but it has the disadvantage of incurring time delay and inferior system efficiency in poor channel environment. To solve these shortcomings, a hybrid automatic repeat request (HARQ) method combining FEC and ARQ is proposed. According to the HARQ method, whether the data received by the physical layer includes an error that cannot be decoded, and when an error occurs, retransmission is requested to improve performance.

A HARQ (Hybrid Auto Repeat Request) receiver basically attempts error correction on received data and determines whether to retransmit using an error detection code. The error detection code may use a cyclic redundancy check (CRC). When the CRC detection process detects an error in the received data, the receiver sends a non-acknowledgement (NACK) signal to the transmitter. The transmitter receiving the NACK signal transmits appropriate retransmission data according to the HARQ mode. The receiver receiving the retransmitted data improves the reception performance by combining and decoding the previous data and the retransmitted data.

The mode of HARQ may be classified into chase combining and incremental redundancy (IR). Chase combining is a method of obtaining a signal-to-noise ratio (SNR) gain by combining with retransmitted data without discarding the data where an error is detected. IR is a method in which additional redundant information is incrementally transmitted to retransmitted data, thereby reducing the burden of retransmission and obtaining a coding gain.

HARQ may be classified into adaptive HARQ and non-adaptive HARQ according to transmission attributes such as resource allocation, modulation technique, transport block size, and the like. Adaptive HARQ is a method in which transmission attributes used for retransmission are changed in whole or in part compared to initial transmission according to a change in channel conditions. Non-adaptive HARQ is a method of continuously using the transmission attribute used for the initial transmission regardless of the change in channel conditions.

Data transmission using HARQ is performed using a mother codeword composed of structured bits and at least one parity bits, which are bit streams associated therewith. When transmitting data in IR mode, a subpacket containing structured bits is transmitted in the first transmission, followed by a subpacket containing parity bits. When all of the mother codewords are transmitted, they are sent cyclically from the structured bit portion. In this case, since all of the mother codes are transmitted, only the SNR gain of HARQ can be obtained, and the coding gain of the IR mode cannot be obtained.

What is needed is a way to more efficiently obtain the coding gain of the IR mode.

An object of the present invention is to provide a data transmission method using HARQ.

A data transmission method using HARQ according to an aspect of the present invention includes transmitting a first subpacket, which is a part of a bit string of a codeword, and a bit stream consecutive to the first subpacket in response to a retransmission request for the codeword. And transmitting a second subpacket, wherein the second subpacket comprises a bit string after a cyclic offset for moving a circulating point of a bit string included in retransmission data.

According to another aspect of the present invention, a data transmission method using HARQ includes generating a plurality of subpackets for data transmission in a mother code consisting of a structured bit and at least one parity bit by a turbo code, and including the structured bit. Transmitting a first subpacket, and transmitting a second subpacket according to a retransmission request for the mother code, wherein the second subpacket has a cyclic offset indicating a recursive point of retransmission data. It consists of bits only.

Coding gain in IR mode can be obtained more efficiently by giving a cyclic offset indicating a recursion point for retransmitted data.

1 is a block diagram illustrating a wireless communication system. Wireless communication systems are widely deployed to provide various communication services such as voice and packet data.

Referring to FIG. 1, a wireless communication system includes a user equipment (UE) 10 and a base station 20 (BS). The terminal 10 may be fixed or mobile and may be called by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device. The base station 20 generally refers to a fixed station that communicates with the terminal 10, and in other terms, such as a Node-B, a Base Transceiver System, or an Access Point. Can be called. One or more cells may exist in one base station 20.

Hereinafter, downlink (DL) means communication from the base station 20 to the terminal 10, and uplink (UL) means communication from the terminal 10 to the base station 20. In downlink, the transmitter may be part of the base station 20 and the receiver may be part of the terminal 10. In uplink, the transmitter may be part of the terminal 10 and the receiver may be part of the base station 20.

The wireless communication system may be an Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiple Access (OFDMA) based system. OFDM uses multiple orthogonal subcarriers. OFDM uses orthogonality between inverse fast fourier transforms (IFFTs) and fast fourier transforms (FFTs). At the transmitter, data is transmitted by performing an IFFT. The receiver performs FFT on the received signal to recover the original data. The transmitter uses an IFFT to combine multiple subcarriers, and the receiver uses a corresponding FFT to separate multiple subcarriers.

2 illustrates a superframe structure.

Referring to FIG. 2, a super-frame SU includes a plurality of frames F and a frame includes a plurality of sub-frames SF.

Each superframe includes a super-frame header. The superframe header includes system information and resource allocation information in the superframe. The synchronization signal may be transmitted through the superframe header. The synchronization signal is a downlink signal for the terminal to synchronize with the base station. The terminal may acquire a cell ID by synchronizing with the base station during an initial access or handover process through a synchronization signal. The synchronization signal may be called a preamble. Superframe may be defined as the transmission period of the superframe header. The superframe header may be transmitted at 20 ms intervals, and a 20 ms superframe may be defined. A 20ms superframe may include four 5ms frames.

The frame may include a downlink frame in which downlink data is transmitted and an uplink frame in which uplink data is transmitted. The downlink frame and the uplink frame may be allocated in a TDD method or an FDD method. The TDD scheme is a scheme in which uplink transmission and downlink transmission are performed at different times while using the same frequency band. In the FDD scheme, downlink transmission and uplink transmission are simultaneously performed through different frequency bands.

One frame may include eight subframes. The subframe may be a basic unit for resource allocation. The subframe includes a plurality of OFDM symbols. The number of OFDM symbols included in the subframe may vary depending on the length of a cyclic prefix (CP). For example, when the CP length is 1/8 of the OFDM symbol time Tu, six OFDM symbols are included in a subframe, and the frame may include 48 OFDM symbols.

Each subframe may be divided into a control region and a data region. User data or control information may be transmitted through the data area. Resource allocation information in a subframe may be transmitted through the control region. In data transmission using HARQ, an ACK / NACK signal may be transmitted through a control region of a subframe. The sequence number of the subframe in which the ACK / NACK signal for the user data transmitted through the preceding subframe is transmitted may be indicated or implicitly designated through the superframe header.

Hereinafter, a data transmission method using HARQ will be described.

3 is a flowchart illustrating an example of a data transmission method using HARQ.

Referring to FIG. 3, the transmitter generates a subpacket (S110). The subpacket may be initially transmitted and retransmitted in units of subpackets in the data transmission process using HARQ. The subpacket may be encoded data encoded by adding a Cyclic Redundancy Check (CRC) to information bits to perform HARQ. As a coding method, a turbo code, which is one of error correction codes, may be applied. A turbo code is a structural code that includes information bits as systematic bits. In the case of a turbo code with a code rate of 1/3, two parity bits are assigned to one structured bit.

The transmitter performs the first transmission (S120). The transmitter transmits a first subpacket generated by applying a turbo code. The first subpacket may include structured bits.

The receiver detects whether the received first subpacket is in error (S130). The receiver attempts error correction on the received first subpacket, and determines whether to retransmit using the CRC, which is an error detection code.

If an error is detected in the first data, the receiver transmits a NACK signal that is a retransmission request signal to the transmitter (S140).

The transmitter receiving the NACK signal performs an appropriate second transmission according to the HARQ mode (chase combining or IR) (S150). In the HARQ of the IR mode, the transmitter transmits a second subpacket, which is a contiguous bit string, to the first subpacket, and the receiver combines and decodes the first subpacket and the second subpacket to improve reception performance.

4 is an exemplary diagram illustrating a subpacket generation process for performing HARQ.

Referring to FIG. 4, data to be transmitted is input as an information block (S210).

A padded block may be padded in the information block to fit a predetermined number of bits for encoding (S220). Channel interleaving is performed to distribute transmission errors according to channels, and the number of bits input to the encoder may be determined according to the size of the channel interleaving. A padding block may be added to match bits input to the encoder to a predetermined number of bits. If the size of the information block is not an element of the allowed set, a padding block may be added to the information block. The acknowledgment set is a set of bits, and the element of the acknowledgment set means the number of bits before the CRC, which is an error detection code, is added to the predetermined number of bits N _EP input to the encoder. For example, the grant set may have {32, 80, 128, 176, 272, 368, 464, 944, 1904, 2864, 3824, 4784, 9584, 14384, 19184, 23984} bits.

CRC, which is an error detection code, is encoded in the information block to which the padding block is added (S230). CRC is added to detect an error in the process of performing HARQ. The CRC may be set to a constant size. For example, the size of the CRC may be 16 bits. The number of bits of the CRC additional packet may be {48, 96, 144, 192, 288, 384, 480, 960, 1920, 2880, 3840, 4800, 9600, 14400, 19200, 24000} bits.

The CRC-encoded packet is divided into encoder blocks having an size that can be input to the encoder (S240). If the size of the CRC encoded packet is larger than the maximum number of bits that can be input to the encoder, the CRC encoded packet is divided into the maximum number of bits. For example, when the maximum number of bits that can be input to the encoder is 4800 bits, if the size of the CRC encoded packet is 9600 bits, it is divided into two encoder blocks. If the size of the CRC encoded packet is smaller than the maximum number of bits, it is not divided.

Randomization is performed for each encoder block (S250). The encoder block becomes a randomized block by randomization. A pseudo-random binary sequence (PRBS) generator may be used for randomization, and the PRBS generator generates randomized blocks by mixing bits of encoder blocks sequentially input.

The randomized block is encoded into a mother codeword by the encoder (S260). The encoder may perform Convolutional Turbo Code (CTC) encoding. The mother code may be composed of structured bits and at least one parity bit associated with the structured bits. If the code rate is 1/3, the mother code includes one structured bit and two parity bits. The error correction code is not limited to a turbo code, but the technical idea of the present invention can be applied to a low density parity check code (LDPC) or other convolution code.

The parent code is disposed according to an interleaving scheme for subpacket generation (S270). According to the interleaving scheme, the bits of the structured bits may be disposed as they are and the parity bits may be interleaved and mixed.

5 shows an example of an interleaving scheme in a subpacket generation process.

Referring to FIG. 5, structured bits and parity bits of a parent code may be divided into at least one subblock. The subblocks are interleaved bit by bit by the subblock interleaver.

The subblocks of the structured bits may be disposed as they are and the subblocks of the parity bits may be interleaved and arranged in units of bits. For example, structured bits are divided into A subblocks and B subblocks, parity bit 1 is divided into Y1 subblocks and Y2 subblocks, and parity bit 2 is divided into W1 subblocks and W2 subblocks. The bits of the A subblock and the B subblock are arranged as they are, while the bits of the Y1 subblock and the Y2 subblock are mixed with each other, and the bits of the W1 subblock and the W2 subblock may be mixed with each other.

Now, a description will be given of a method of transmitting and configuring the arranged bits into subpackets according to HARQ in incremental redundancy (IR) mode. HARQ data retransmission may be performed synchronously or asynchronously according to SAW (stop and wait), GBN (Go-back-N), and SR (selective repeat). In this case, the retransmitted data is transmitted after the transmission attribute such as resource allocation, modulation technique, transport block size, etc. is adaptively changed according to channel conditions according to adaptive HARQ, or used for initial transmission according to non-adaptive HARQ. It can be transmitted by continuously applying the transmission attribute.

6 shows a data transmission method using non-adaptive HARQ (IRQ) of the IR mode.

Referring to FIG. 6, in the non-adaptive HARQ scheme of the IR mode, retransmission data may be incrementally transmitted after the previously transmitted data. Initial data refers to a subpacket transmitted through the first transmission, and retransmission data refers to a subpacket transmitted through the retransmission process after the first transmission. The subpackets of the first transmission include some bit strings of the parent codewords, and the subpackets of the second transmissions are made up of bit streams contiguous with the subpackets of the first transmission. In non-adaptive HARQ, retransmission data is transmitted at the same size as the original data. That is, subpackets having the same size as the subpackets transmitted through the first transmission in the non-adaptive HARQ are transmitted through the second, third, and fourth transmissions.

When the index of the retransmission data is equal to the length N _EP / R _M of the mother codeword, the retransmission data may be cyclically transmitted. R _M is the mother code rate and N _EP is the size of the encoder block entering the encoder. When the encoder uses the Convolutional Turbo Code (CTC) of double binary (duo-binary) structure, N _EP is the number of bits input to the CTC turbo encoder and is a parameter defined as the size of the encoder block. . When the size of the internal interleaver of the CTC turbo encoder is N, N _EP = 2 × N.

The mother code may be composed of structured bits having a bit string having the same size as an encoder block input to the encoder and at least one parity bits corresponding to the bit string. The parent codeword may be a turbo codeword. The length of the parent word is N _EP / R _M.

In the IR mode, some bit strings including the structured bits of the mother code are configured as a first subpacket and transmitted first, and some other bit streams are incrementally transferred to the second subpacket according to a retransmission request for the mother code. A second transmission. That is, some bit strings of the mother code are composed of subpackets and transmitted through initial transmission and retransmission. If the length of the retransmission subpacket following the bit stream of the previously transmitted subpacket exceeds the range of the parent code, the bit stream of the retransmission subpacket is cyclically generated from the last bit of the parent code to the bit at a predetermined position. If the sum of the length of the first subpacket and the length of the second subpacket exceeds the length of the parent codeword, the portion exceeding the length of the parent codeword is cyclically transmitted.

When the mother coding rate R _M = 1/3 and the size of the encoder block input to the encoder is N _EP , the subpacket transmitted in the initial transmission and retransmission may be configured as in Equation 1 below.

Where k is the number of retransmissions (if k = 0, first (new) transmission, S _k is the k-th data, F _k is the start of the k-th data, i is the bit with the i-th index, and L _k is The length of the k th data transmitted through the channel N _SCHk is the number of unit resources, SPID _k is the version of the k th data (first transmission is always SPID = 0), 0, 1, 2, 3, 0, 1, can be repeated to .... M _k is the modulation order (modulation order). If the modulation method is BPSK (Banary-Phase Shift Keying) when the _{M k = 1, QPSK (Quadrature} -Phase Shift Keying) M k In the case of = 2 and 8 PSK, M _k = 3 and in the case of 16 Quadrature Amplitude Modulation (QAM), M _k = 4 and M _k = 6 in case of 64 QAM.

In the chase combining mode, the initial transmission part is repeatedly transmitted at retransmission. On the other hand, in the IR mode, retransmission data is transmitted after previously transmitted data, and when all mother codes are transmitted, the retransmission data is sequentially transmitted from the structured bit portion. Since all of the mother codes are transmitted, the coding gain of the IR mode is not obtained, and only the signal-to-noise ratio (SNR) gain of HARQ can be obtained. When re-transmission in the HARQ of the IR mode, a better coding gain of the IR mode can be obtained when the parity bit is transmitted repeatedly than the structured bits of the turbo code are repeatedly transmitted.

7 shows a data transmission method using non-adaptive HARQ of the IR mode according to an embodiment of the present invention.

Referring to FIG. 7, after the initial data is transmitted, retransmission data is incrementally transmitted according to a retransmission request. The bit string of a subpacket composed of retransmission data varies according to a cyclic offset. The cyclic offset is an offset for shifting a cyclic point of a bit string included in retransmitted data when data is cyclically transmitted after all mother codes are transmitted according to the IR mode. The cyclic offset may be determined by the size of the structured bits such that the data to be retransmitted is the parity bits of the parent code. Alternatively, the cyclic offset may be set smaller or larger than the size of the structured bit as needed.

Equation 2 shows a method of moving a recursive point of retransmission data in non-adaptive HARQ of the IR mode.

Where k is the number of retransmissions (if k = 0, first (new) transmission, S _k is the k-th data, F _k is the start of the k-th data, i is the bit with the i-th index, and L _k is the length of the k-th data being transmitted over the channel. N _SCHk the number of unit resources, N _SUBk is the number of sub-carriers per for OFDMA unit resources as the number of symbols that can silyl per unit resource. SPID _k is k The first version of the data (first transmission is always SPID = 0) and can be repeated 0, 1, 2, 3, 0, 1, ... M _k is the modulation order F _OFFSET k is k Circular offset to shift the circular point of the second data.

If the cyclic offset is set to the size of the structured bit, the parity bit portion is transmitted after all of the parent codes have been transmitted. When the cyclic offset becomes zero, the structured bit portion is transmitted after all the parent codes are transmitted as in the conventional method. If the cyclic offset is smaller than the size of the structured bits, some of the structured bits may be included in the retransmission data. That is, the parity amount of retransmission data may be adjusted by adjusting the value of the cyclic offset. The value of the cyclic offset may be predetermined or changed according to the number of retransmissions. Alternatively, a separate calculation formula for calculating the cyclic offset may be provided to determine the value of the cyclic offset.

Here, the case where the cyclic offset F _OFFSETk is determined as the size of the structured bit in the non-adaptive HARQ of the IR mode in which the mother coding rate R _M = 1/3 and the size of the subpacket L _k = 2N _EP is shown. The subpacket of the second transmission incrementally transmitted in the first transmission is generated by moving the cyclic point by the cyclic offset following the last bit string of the parent code. The subpacket of the second transmission consists of a bit string after the cyclic offset. The subpacket of the second transmission may not include structured bits but only parity bits.

In non-adaptive HARQ of the IR mode, the structured bits are repeatedly transmitted when retransmitted with a cyclic offset, and the parity bits are transmitted so that the coding gain of the HARQ in the IR mode can be more efficiently obtained.

8 shows a data transmission method using adaptive HARQ in the IR mode according to an embodiment of the present invention.

Referring to FIG. 8, in the adaptive HARQ scheme, transmission attributes such as a decrease in allocated resources and a change in modulation order may be changed during retransmission. When the length L _k of the retransmission data is changed compared to the original data, data duplicated with previously transmitted data may be transmitted according to Equation 2. If the retransmission data overlaps with the previously transmitted data, the coding gain of the IR mode cannot be sufficiently obtained.

Equation 3 shows a method of moving a recursive point of retransmission data in adaptive HARQ in IR mode.

Here, E _k is the last point of the k-th data, F ₀ is the start point of the data selected during the first transmission. In general, F ₀ may be 0, but may be set to another value in some cases.

Even if the length L _k of retransmission data is changed compared to the original data, retransmission data is transmitted after the last point E _k-1 of the preceding data, so the retransmission data does not overlap with the preceding data. When the length of the retransmission data is fixed, the retransmission data may be transmitted as shown in Equation 2.

Even in the adaptive HARQ of the IR mode, the cyclic offset may be set to the size of the structured bit. If the cyclic offset is set to the size of the structured bit, the parity bit portion is transmitted after all of the parent codes are transmitted. By adjusting the value of the cyclic offset, the parity amount of retransmission data may be adjusted. The value of the cyclic offset may be predetermined or changed according to the number of retransmissions. Alternatively, a separate calculation formula for calculating the cyclic offset may be provided to determine the value of the cyclic offset.

Even in the adaptive HARQ of the IR mode, when the retransmission is performed with a cyclic offset, it is possible to reduce the repetitive transmission of the structured bits and to transmit the parity bits so that the coding gain of the HARQ of the IR mode can be efficiently obtained.

9 shows a data transmission method using HARQ according to an embodiment of the present invention.

Referring to FIG. 9, the base station transmits HARQ information including a cyclic offset (F _offset ) to the terminal (S310). The cyclic offset value may be determined by the base station and inform the terminal. The cyclic offset value may be transmitted through system information or through a dedicated control channel for the terminal. The cyclic offset adjusts the amount of parity included in retransmission data in adaptive or non-adaptive HARQ of IR mode. By reducing the structured bits that can be included in the retransmission data and increasing the parity bits, the coding gain of the HARQ in the IR mode can be more efficiently obtained.

The base station transmits initial data to the terminal (S320). The base station uses the turbo code to generate a mother code consisting of structured bits and at least one parity bit. A plurality of subpackets are generated that include some bit strings of the parent code. The original data may be a subpacket consisting of some bit strings of the mother code generated by applying the turbo code. Initial data may include structured bits.

The terminal detects whether the received initial data is an error (S330). The terminal attempts error correction on the first received data and determines whether to retransmit using the CRC, which is an error detection code.

If an error is detected in the initial data, the terminal transmits a NACK signal that is a retransmission request signal to the base station (S340).

The base station receiving the NACK signal generates and transmits appropriate retransmission data according to the IR mode HARQ (S350). In this case, the base station generates retransmission data by adjusting the parity amount included in the retransmission data according to the cyclic offset. The terminal can improve reception performance by decoding the retransmission data received according to the cyclic offset with the original data.

Here, although the base station assumes a downlink HARQ process for transmitting data to the terminal, the present invention can be equally applied to the uplink HARQ process for transmitting data to the base station.

10 is a graph showing the performance of HARQ when a cyclic offset is applied according to an embodiment of the present invention.

Referring to FIG. 10, when the mother coding rate R _M = 1/3 and the size of the subpacket L _k = 2N _EP , a non-adaptive HARQ scheme and a proposal of the conventional IR mode using a convolutional turbo code of a dual binary structure A block error rate (BLER) according to a signal-to-noise ratio (SNR) of a non-adaptive HARQ scheme of an IR mode to which a cyclic offset F _OFFSETk = N _EP is applied. The channel assumes Additive White Gaussian Noise (AWGN).

It can be seen that the proposed method outperforms the existing method.

All the above functions may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), or the like according to software or program code coded to perform the function. The design, development and implementation of the code will be apparent to those skilled in the art based on the description of the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

1 is a block diagram illustrating a wireless communication system.

2 illustrates a superframe structure.

3 is a flowchart illustrating an example of a data transmission method using HARQ.

4 is an exemplary diagram illustrating a subpacket generation process for performing HARQ.

5 shows an example of an interleaving scheme in a subpacket generation process.

6 shows a data transmission method using non-adaptive HARQ (IRQ) of the IR mode.

7 shows a data transmission method using non-adaptive HARQ of the IR mode according to an embodiment of the present invention.

8 shows a data transmission method using adaptive HARQ in the IR mode according to an embodiment of the present invention.

9 shows a data transmission method using HARQ according to an embodiment of the present invention.

10 is a graph showing the performance of HARQ when a cyclic offset is applied according to an embodiment of the present invention.

Claims (9)

In the data transmission method using HARQ, Transmitting a first subpacket which is a part of a bit string of codewords; And And transmitting a second subpacket consisting of consecutive bit streams to the first subpacket according to a retransmission request for the codeword, wherein the second subpacket moves a cycle point of a bit stream included in retransmission data. A data transmission method using HARQ consisting of a bit string after a cyclic offset. The method of claim 1, wherein the codeword is a turbo code applied to each other, thereby forming structural bits and at least one parity bits. 3. The method of claim 2, wherein the cyclic offset includes a range of the structured bits. 3. The method of claim 2, wherein the cyclic offset is determined by the size of the structured bit. The method of claim 1, wherein the second subpacket is transmitted in the same size as the first subpacket. The method of claim 1, wherein the second subpacket is transmitted in a different size from the first subpacket. In the data transmission method using HARQ, Generating a plurality of subpackets for data transmission in a mother code consisting of a structured bit and at least one parity bit by a turbo code; Transmitting a first subpacket including the structured bits; And And transmitting a second subpacket according to a retransmission request for the mother codeword, wherein the second subpacket includes only bits after a cyclic offset indicating a recursion point of retransmission data. . 8. The method of claim 7, wherein the cyclic offset is transmitted through system information or a dedicated control channel. 8. The method of claim 7, wherein the second subpacket comprises only the parity bits.

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