KR100908064B1 - Method for transporting downlink control information - Google Patents

Abstract

A downlink control information transmitting method in a multiple antenna communications system is provided to transmit downlink control information according to a codeword swapping in the multiple antenna communications system. An MCS(Modulation and Coding Scheme) information about each information transmitted through two coding words, an NDI(New Data Indicator) and RV(redundancy version) are transmitted in a multiple antenna communications system. Additional control information transmits one or more among a swapping indicator, which shows whether to swap the information transmitted through two code word, and code word activation information, which shows whether to deactivate the transmission of the codeword. In case the transmission of one coding word is deactivated among two coding words, the use of the swapping pointer is reserved.

Description

How to pass downlink control information {METHOD FOR TRANSPORTING DOWNLINK CONTROL INFORMATION}

The present invention relates to a multi-antenna communication system, and more particularly, to a method of efficiently transmitting downlink control information including information on codeword swapping and activation.

Error control algorithms used in current communication systems can be classified into two types, namely, automatic repeat request (ARQ) and forward error correction (FEC). Types of ARQ include Stop and Wait ARQ, Go-Back-N ARQ, and Selective-Repeat ARQ. Stop and Wait ARQ is a technique that transmits the next frame after confirming the correct reception of each transmitted frame (ACK signal confirmation), and Go-Back-N ARQ transmits N consecutive data frames and successfully transmits them. If this is not done, all data frames transmitted after the frame in which the error occurs are retransmitted. The selective iterative ARQ technique is a method of selectively retransmitting only an error frame.

On the other hand, HARQ (Hybrid Automatic Repeat reQuest) is a technology that controls the error by combining retransmission and error correction, a method of maximizing the error correction code capability of the data received during retransmission. According to the characteristics of bits transmitted during retransmission, it can be divided into chase combing (CC) and incremental redundancy (IR) HARQ. Chase combining HARQ is a method to obtain gain by increasing the SNR ratio at the receiver by using the data used in the first transmission when retransmission, and IR HARQ transmits and combines redundancy bits during retransmission. In this method, a coding gain is obtained at a receiving end to improve performance.

1 is a view for explaining the concept of the Stop and Wait ARQ scheme of the HARQ scheme.

As shown in FIG. 1, the Stop and wait HARQ protocol is a method of determining whether to retransmit by receiving ACK (ACKnowledgement) / NACK (No ACK) separately from a receiving end after transmitting one process block. Although this Stop and wait HARQ protocol is the simplest and most efficient transmission method, the link transmission efficiency is reduced due to the rounding trip time ("RTT") until the transmitting end of the data receives the ACK / NACK from the receiving end of the data. Degrades.

2 is a diagram for explaining an N-channel Stop and wait HARQ protocol technique.

That is, the N-channel Stop and wait HARQ protocol scheme can be used for various periods of time when the transmission link is not used until the ACK / NACK is exchanged as shown in FIG. 2 to compensate for the problems described above with reference to FIG. 1. It refers to a technique for operating the independent (N) stop-and wait HARQ. This can reduce processing delays.

On the other hand, MIMO (Multiple Input Multiple Output) technique refers to a method of increasing the capacity of the system by transmitting multiple data streams simultaneously using two or more transmitting and receiving antennas at the base station and the terminal. A transmission diversity gain or beamforming gain is obtained by using a plurality of transmission antennas.

The transmit diversity scheme enables reliable data transmission in fast time-varying channel situations by transmitting the same data information through multiple transmit antennas, and has an advantage that it can be implemented without channel related feedback information from a receiver. Beamforming is used to increase the receiver SINR (Signal to Interference plus Noise Ratio) of a receiver by multiplying a plurality of transmit antennas by appropriate weights, and is generally used for uplink / downlink transmission in a frequency division duplexing (FDD) system. Since the channel is independent, highly reliable channel information is required to obtain a proper beamforming gain. Therefore, a separate feedback from the receiver is used.

Meanwhile, the spatial multiplexing method for a single user and multiple users will be briefly described as follows.

FIG. 3 is a diagram illustrating the concept of spatial multiplexing (SM) and spatial divisional multiple access (SMD) schemes used in a MIMO communication system.

Spatial multiplexing for a single user is referred to as SM or SU-MIMO (Single User MIMO), and by using a plurality of antennas of one user in a manner as shown on the left side of FIG. It increases in proportion to the number of antennas. Meanwhile, spatial multiplexing for multiple users is called SDMA or MU-MIMO (Multi-User MIMO), and data transmission and reception are performed through a plurality of user antennas as shown in the right side of FIG. 3.

When using the MIMO scheme, a single codeword (SCW) scheme for transmitting N data streams simultaneously transmitted using one channel encoding block and M data streams in which M is always less than or equal to N There is a multiple codeword (MCW) scheme for transmitting using) channel encoding blocks. At this time, each channel encoding block generates an independent codeword and each codeword is designed to enable independent error detection.

Meanwhile, the codewords as described above are transmitted through one or more layers, and the information transmitted through each codeword may be transmitted by swapping with each other. In addition, in a wireless communication system capable of transmitting a plurality of codewords simultaneously, certain codewords may be disabled.

An object of the present invention is to provide a method for efficiently transmitting downlink control information including information on codeword swapping and activation in a multi-antenna communication system as described above.

In one aspect of the present invention for solving the above problems, as a method for transmitting control information in a multi-antenna system capable of transmitting up to two codewords at the same time, for each information transmitted through the two codewords Among the two codewords and a swapping indicator that transmits Modulation and Coding Scheme (MCS) information, a new data indicator (NDI), a redundancy version (RV), and the like, and whether the information transmitted through the two codewords is swapped. Transmitting additional control information including at least one of the codeword activation information indicating whether any one of the codeword transmissions is deactivated, wherein any one of the two codewords is deactivated. The downlink indicator is characterized in that the swapping indicator is configured to be reserved for use. It provides information delivery methods.

In another aspect of the present invention, as a method of receiving control information in a multi-antenna system capable of simultaneously receiving up to two codewords, MCS (Modulation and Coding) for each information transmitted through the two codewords Receive Scheme) information, a new data indicator (NDI) and a redundancy version (RV), and a swapping indicator indicating whether or not swapping of information transmitted through the two codewords and transmitting one of the two codewords Receiving additional control information including one or more of codeword activation information indicating whether or not to be deactivated, wherein the swapping indicator is used when any one of the two codewords is deactivated. Provided is a method for receiving downlink control information, which is reserved.

In this case, through the additional control information including at least one of the swapping indicator and the codeword activation information, in the first case that the two codewords are transmitted without swapping, the second codewords are swapped with each other and transmitted. In this case, any one of the two codewords may be deactivated, and each codeword information may be set to indicate a third case and a fourth case as two cases in which the codeword information is transmitted through the activated codeword.

In addition, when both codewords are activated, the swapping indicator is included as explicit 1-bit information in downlink control information, and the codeword activation information is included in the new data indicator (NDI) and the redundancy version (RV). ) May be set to be implicitly delivered according to a combination of one or more of the MCS information.

According to each embodiment of the present invention as described above, downlink control information including information according to codeword swapping and activation can be efficiently delivered in a multi-antenna communication system.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form, centering on the core functions of each structure and device, in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

As described above, the present invention is to provide a method for efficiently transmitting downlink control information including information according to codeword swapping and activation in a multi-antenna communication system. To this end, in the following, the transmission relationship of codewords and control information generally required for downlink transmission in a multi-antenna system will be described, and then the above-described swapping information and codeword deactivation information will be described. Look at it.

4 is a diagram illustrating a structure of a transmitting end of a MIMO system using multiple codewords.

Specifically, M data packets generate M codewords through encoding (for example, turbo encoding of FIG. 4) and modulation (for example, QAM modulation of FIG. 4), respectively, and each code The word will have an independent HARQ process block. The modulated M data symbols are simultaneously encoded according to a multiple antenna scheme in the MIMO stage and transmitted through each physical antenna. Subsequently, the receiving end may adjust the spatial multiplexing rate, coding rate, and modulation scheme by feeding back channel quality information in a multi-antenna channel situation.

In addition, for MIMO transmission as shown in FIG. 4, MCS information on the modulation and coding scheme used by the transmitting end, a new data indicator (NDI) indicating whether the transmitted data is new data or retransmitted data, and in case of retransmission, Redundancy version (RV) information about whether to retransmit the subpacket is required.

Meanwhile, the mapping relationship between the codeword and the physical antenna may have any form.

5 is a diagram illustrating a mapping relationship between a codeword and a physical antenna.

FIG. 5 illustrates a codeword-to-layer mapping for spatial multiplexing in DL according to spatial multiplexing rate in downlink in 3GPP TS 36.211. That is, when the spatial multiplexing rate is 1, one codeword is mapped to one layer, and data generated in one layer by the precoding scheme is encoded to be transmitted through four transmission antennas. In the case where the spatial multiplexing rate is 2, a form in which two codewords are mapped to two layers and mapped to four antennas by a precoder is illustrated. In addition, when the spatial multiplexing rate is 3, one codeword of two codewords is mapped to two layers by a serial-to-parallel converter (S / P), so that a total of two codewords are mapped to three layers and then free. The coder maps to four antennas. In addition, when the spatial multiplexing rate is 4, an example in which two codewords are each mapped to two layers by a serial-to-parallel converter, and a total of four layers are mapped to four antennas by a precoder is illustrated.

That is, a base station having four transmit antennas may have up to four layers and may have four independent codewords, but FIG. 5 illustrates a system configured to have only two codewords, for example. Doing. Therefore, in the system shown in FIG. 5, it can be seen that up to two independent HARQ processes can be transmitted if each codeword CW has an independent HARQ process.

On the other hand, the precoder is usually expressed as Mt (number of transmit antennas) * v (spatial multiplexing rate) matrix, and the precoding matrix is appropriately suited to the situation by using a set of matrices predetermined by the transmitter / receiver. Adaptive use The set of such precoding matrices is called a codebook. For example, Tables 1 and 2 below show examples of codebooks used for downlink in 3GPP TS 36.211.

TABLE 1

TABLE 2

Specifically, Table 1 shows a codebook used in a two antenna system (2 Tx system), and Table 2 shows a codebook used in a four antenna system (4 Tx system).

On the other hand, in the Stop-And-Wait HARQ method, the data receiver checks whether the data is successfully received through an error detection code such as a cyclic redundancy check (CRC). For convenience, in this description, a data unit in which an error can be detected is referred to as a 'HARQ process block'. In addition, an identifier used to distinguish HARQ process blocks that can be transmitted within a predetermined interval in the system, for example, within a round trip time, is referred to as a HARQ process number.

If an error of data is not detected, the receiving end transmits an ACK signal, and if an error is detected, the receiving end transmits a NACK signal. The data transmitting end receiving the ACK signal then transmits the data. The data transmitting end receiving the NACK signal retransmits the corresponding data having an error. In this case, the retransmitted data may change the format of the retransmitted data according to the HARQ type.

Meanwhile, when the transmission bandwidth is wide or when data is transmitted using multiple antennas, a plurality of HARQ process blocks may be simultaneously transmitted.

FIG. 6 is a diagram for describing a multiple HARQ scheme of simultaneously transmitting m HARQ process blocks and receiving an ACK / NACK signal for each HARQ process block.

That is, the transmitting side may simultaneously transmit a number (m) of HARQ process blocks in a predetermined transmission unit as shown in FIG. In response, the receiving end may transmit m ACK / NACK signals for m HARQ process blocks to the data transmitting end. Furthermore, the multiple stop-and-wait HARQ scheme as shown in FIG. 6 may be combined with the N-channel stop and wait HARQ scheme described above with reference to FIG.

That is, the number of combinations of HARQ process numbers that may occur in a system in which at most n HARQ process blocks can operate in the RTT and transmit m HARQ process blocks simultaneously is as follows.

[Equation 1]

가 된다.

Becomes

The number of bits x of control signaling to express the combination of all HARQ process numbers for supporting this is as follows.

[Equation 2]

On the other hand, if the number of HARQ process blocks transmitted at the same time, that is, the number of layers to be used at the same time through a signal, the number of bits x of the control signaling for representing a combination of HARQ process numbers can be expressed as follows.

[Equation 3]

As a method for reducing the overhead of such control information, there is a technique in which N bit used to distinguish HARQ process IDs in SIMO is used in MIMO as it is.

FIG. 7 is a diagram for describing a method of configuring simultaneous HARQ process blocks to be shared by using HARQ process numbers.

In detail, FIG. 7 illustrates a case in which up to 8 HARQ process blocks may operate during a round trip time (RTT), and two layers may be simultaneously used, so that up to 16 HARQ process blocks may be transmitted during RTT. . However, FIG. 7 illustrates an example in which HARQ process blocks transmitted simultaneously share and use HARQ process numbers 0 to 7 so that the HARQ process number can be expressed using only 3 bits of control information.

Based on this description, the following control information is used in the 3GPP LTE system for MIMO transmission as described above with reference to FIG. 4, layer mapping, precoding, and HARQ process number signaling as described above with reference to FIG. It is becoming.

TABLE 3

However, the following problem may occur with only the control information form described above.

For example, assume a multi-antenna system capable of transmitting up to two codewords and having four transmit antennas. In this case, when the spatial multiplexing rate is 4, the first codeword CW1 may be transmitted through the (1, 2) th layer, and the second codeword CW2 may be transmitted through the (3, 4) th layer. . In this case, error detection is possible in codeword units, so if an error is detected only in CW1, and the channel situation changes at the time of retransmission and the spatial multiplexing rate needs to be transmitted as 2, the CW1 in which the error occurs is chase combining. There is a problem that cannot use the HARQ method such as.

In addition, if all the CW2 transfers are completed and the CW2 buffer is empty, it is impossible to properly cope with the situation in which only CW1 is transmitted despite the current spatial multiplexing rate of 4.

In the case of sharing multiple HARQ process blocks simultaneously transmitted in a MIMO mode as one HARQ process block, the location where data is mapped to a layer is changed or a single data is generated due to antenna selection or rank adaptation during retransmission. If is transmitted, it is not possible to recognize only the HARQ process number.

In order to solve the above problem, one embodiment of the present invention proposes to send null data to a specific CW.

8 illustrates a concept of transmitting null data in a specific codeword according to an embodiment of the present invention.

Specifically, FIG. 8 shows null data in one CW when a buffer of one CW suddenly becomes empty or the spatial multiplexing rate of a channel decreases in a situation in which the spatial multiplexing rate is transmitted to 2 or more among the layer mapping relationships as shown in FIG. 5. FIG. 8A illustrates a case where null data is transmitted in codeword A, and FIG. 8B illustrates a case where null data is transmitted in codeword B. As shown in FIG.

In this way, multiple antenna schemes are used, as if both CWs are used on the surface. As such, when null data is transmitted through a specific codeword, the corresponding codeword may be expressed as disabled. In addition, in the present invention, the specific codeword is inactivated when the codeword transmission itself is inactivated (when null data is transmitted) and when the information transmitted through each codeword is inactivated. For example, although FIG. 8 illustrates a case in which CW1 or CW2 is inactivated, the concept includes a case in which a size of transport block 1 / transport block 2 mapped to CW1 / CW2 is 0.

In addition, one embodiment of the present invention proposes setting so that the positions of CW1 and CW2 can be changed and transmitted.

FIG. 9 is a diagram illustrating a concept in which codewords are swapped and transmitted according to an embodiment of the present invention.

In FIG. 9, when two or more codewords among the layer mapping relationships as illustrated in FIG. 5 are transmitted, a position where CW1 and CW2 are transmitted is swapped. However, in the present invention, swapping assumes a concept that includes not only a case where a transmission position of two codewords is changed but also a case where information transmitted through each codeword is changed and mapped to codewords. For example, when a transport block is mapped and transmitted to each codeword, it is not necessary to change the transport location of the codeword itself but to change the location where each transport block is mapped to the codeword. The concept is included.

Therefore, the indexing of the HARQ process block as shown in FIG. 7 is proposed to be changed as follows.

FIG. 10 is a diagram illustrating a concept of distinguishing between HARQ process blocks transmitted at the same time and enabling swapping and null data transmission of HARQ process blocks transmitted simultaneously according to an embodiment of the present invention.

That is, FIG. 10 is required to be distinguished from each other, as indicated by "a" and "b" between HARQ process blocks transmitted simultaneously, and retransmission by distinguishing "a" and "b" even when retransmitting. Suggest.

In addition, when mapping each HARQ process block to a layer, it is desirable to be able to swap the layer mapping of "a" and "b".

To this end, an embodiment of the present invention proposes to transmit additional control information to a receiving side to distinguish the following six states.

TABLE 4

In Table 4, "Swapping" indicates a case where a transmission position is changed between codewords, or information mapped to each codeword is exchanged, and "null Tx" indicates when null data is transmitted to CW A or CW B, or The case in which the transport block mapped to each codeword is inactivated is shown.

When the above information is indicated in the downlink control information field, it may be expressed explicitly or implicitly. For example, a control information field for expressing the cases of Table 4 may be explicitly added to Table 3 above. At this time, if all the cases are considered, three bits of control information are required to represent six cases.

However, the 3-bit control information that must be present to represent all six cases is a number of bits that can represent eight cases, and may be considered to include some overhead to represent six cases. Therefore, in one preferred embodiment of the present invention, it is proposed to maintain similar performance while reducing control information overhead by reducing the six cases of Table 4 to four cases as shown in Table 5 below.

TABLE 5

Specifically, in Table 5, when CWA or CWB in Table 4 is inactivated, two cases are omitted by suspending the use of a swapping function. That is, in this embodiment, when one codeword is inactivated, the swapping position of the codewords has a small profit compared to the case where two codewords are transmitted. Suggest that.

As described above, the four state information of Table 5 may be implicitly conveyed through explicit signaling or through other control information.

According to an embodiment of the present invention, it is proposed to indicate whether or not swapping is performed using two bits of RSN field information of Table 3 above. For example, if the RSN field is 0, it may indicate that swapping is not used, and if the RSN field is 1 to 3, it may be set to indicate that swapping is performed. In another embodiment of the present invention, a new data indicator (NDI) of 1 bit and RSN information of 2 bits may be used to indicate whether or not swapping is performed as follows.

TABLE 5

Alternatively, if an extra state exists in any of the control information fields, information necessary for this state may be added and expressed.

For example, if there is an extra state in the Precoding information field as shown in Table 1, a state indicating a swapping CW A / B, which is one of necessary information, may be added to this empty state.

TABLE 6

The upper end of Table 6 represents Table 1 as it is, and the lower end of Table 6 shows that a precoding matrix indicating CW swapping is added to the empty state of Table 1.

You can also add other information as needed if there is more redundant state.

In another embodiment of the present invention, the codebook shown in Table 1 may be modified as follows to indicate that a specific codeword is deactivated.

TABLE 7

In Table 7, the " number of layer " field and the precoding information field are represented by the same column in the codebook of Table 1, and indexes 0 to 5 are information on rank 1, and the rest of the indexes are information on rank 2. The set example is shown. In particular, indexes 9 through 11 indicate "null Tx A", that is, codeword A transmits null data, and indexes 12 through 14 represent "null Tx B", that is, codeword B transmit null data. .

One embodiment of the present invention proposes a method of implicitly informing downlink control information as explicit 1-bit information about whether or not to swap, and other control information as shown in Table 7 above for deactivation of a specific codeword. do.

As an example of such an embodiment, Table 8 below shows an example of using explicit 1-bit information about swapping and using precoding information as shown in Table 7 above for the codeword activation state.

TABLE 8

In the example of Table 8, state "1" or "2" indicates a state according to an explicit swapping flag, and in Table 7, indexes 6 to 14 correspond to layer 2, and thus different states depending on whether or not swapping is performed. Will be displayed. In particular, in the case of the indexes 9 to 14, the specific codewords are deactivated.

As described above, the same state may be used in various meanings using the control information field.

As another example, if the transmission formats of the first transport block and the second transport block of Table 3 mean that the size of the data is '0', as in the example of Table 8, an explicit swapping flag is set for whether or not to swap. For the null Tx, the following status information may be indicated according to one or more combinations of other control information, for example, a new data indicator (NDI), a redundancy version (RV), and MCS information.

TABLE 9

Meanwhile, there are various ways in which the transmission formats of the first transport block and the second transport block can express the meaning that the data size is '0'. One of them may represent a state having a size of '0' in the state of the transport format field. In addition, if the size is '0', there is a method that does not represent the field itself. If the meaning implies that the first transport block is mapped to CW1 and the second transport block is mapped to CW2, the transport format field of the first transport block is removed to express CW1, and the second to deactivate CW2. The transport format field of the transport block can be removed.

However, if one data is transmitted to the first transport block, if one data is always transmitted regardless of whether it is CW1 or CW2, the data size may be set to be transmitted through the transport format field of the first transport block. . In this case, it is assumed that CW1 / CW2 can be explicitly or implicitly distinguished through arbitrary state information.

When a state having a size of '0' is added to a transport format field of a first transport block and a second transport block, and explicit swapping information is used, all four states required according to the present embodiment may be represented.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

As described above, the method for transmitting control information according to each embodiment of the present invention can transmit not only the above-described 3GPP LTE system but also up to two codewords simultaneously, and any multiplication that requires swapping and deactivation of a specific codeword is required. It is apparent to those skilled in the art that the antenna system can be applied by the same principle.

1 is a view for explaining the concept of the Stop and Wait ARQ scheme of the HARQ scheme.

2 is a diagram for explaining an N-channel Stop and wait HARQ protocol technique.

3 is a diagram illustrating the concept of a spatial multiplexing (SM) and a spatial divisional multiple access (SM) scheme used in a MIMO communication system.

4 is a diagram illustrating a structure of a transmitting end of a MIMO system using multiple codewords.

5 is a diagram illustrating a mapping relationship between a codeword and a physical antenna.

FIG. 6 is a diagram for describing a multiple HARQ scheme of simultaneously transmitting m HARQ process blocks and receiving an ACK / NACK signal for each HARQ process block.

FIG. 7 is a diagram for describing a method of configuring simultaneous HARQ process blocks to be shared by using HARQ process numbers.

8 illustrates a concept of transmitting null data in a specific codeword according to an embodiment of the present invention.

FIG. 9 is a diagram illustrating a concept in which codewords are swapped and transmitted according to an embodiment of the present invention.

FIG. 10 is a diagram for describing a concept of distinguishing between HARQ process blocks transmitted simultaneously and swapping and transmitting null data of HARQ process blocks transmitted simultaneously according to an embodiment of the present invention.

Claims (6)

In a method of transmitting control information in a multi-antenna system capable of transmitting up to two codewords at the same time, Transmitting Modulation and Coding Scheme (MCS) information, a new data indicator (NDI) and a redundancy version (RV) for each of the information transmitted through the two codewords; And Additional control information including at least one of a swapping indicator indicating whether information transmitted through the two codewords is swapped and codeword activation information indicating which one of the two codewords is deactivated; Sending a step, And when the codeword transmission of any of the two codewords is disabled, the swapping indicator is reserved for use. The method of claim 1, Through additional control information including one or more of the swapping indicator and the codeword activation information, In the first case in which the two codewords are transmitted without swapping, in the second case in which the two codewords are swapped and transmitted, one codeword of the two codewords is deactivated, and each codeword information is And a third case and a fourth case as two cases transmitted through the activated codeword. The method of claim 1, The swapping indicator is included as explicit 1 bit information in downlink control information, The codeword activation information is implicitly delivered according to one or more combinations of the new data indicator (NDI), the redundancy version (RV), and the MCS information. A method of receiving control information in a multi-antenna system capable of receiving up to two codewords simultaneously, Receiving Modulation and Coding Scheme (MCS) information, a new data indicator (NDI), and a redundancy version (RV) for each of the information transmitted through the two codewords; And Additional control information including at least one of a swapping indicator indicating whether information transmitted through the two codewords is swapped and codeword activation information indicating which one of the two codewords is deactivated; Receiving; And when the one of the two codewords is deactivated, the swapping indicator is reserved for use. The method of claim 4, wherein Through additional control information including one or more of the swapping indicator and the codeword activation information, In the first case in which the two codewords are transmitted without swapping, in the second case in which the two codewords are swapped and transmitted, one of the two codewords is deactivated, and each codeword information is activated. And obtaining information on the third and fourth cases as the two cases transmitted through the codeword. The method of claim 4, wherein The swapping indicator is received as included in the downlink control information as explicit 1-bit information, The codeword activation information is implicitly recognized according to one or more combinations of the new data indicator (NDI), the redundancy version (RV), and the MCS information.

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