ES2706294T3 - Procedure for transmitting downlink control information - Google Patents

Abstract

A method for transmitting control information in a multi-antenna system that can simultaneously transmit a maximum of two code words, the procedure comprising: transmitting modulation and coding scheme information, called MCS, a new data indicator, called NDI, and a redundancy version, called RV, for blocks of information transmitted through the two code words; and transmitting additional control information that includes at least one of an exchange indicator and enable / disable information, indicating the exchange indicator whether or not there is an exchange between the blocks of information transmitted through the two words of code, and indicating the enable / disable information if any one of the transmissions through the two code words is or is not disabled, in which: the exchange indicator is reserved when any one of the transmissions through the Two code words are disabled, and the exchange indicator is transmitted within downlink control information as explicit one-bit information, characterized in that the enable / disable information is implicitly transmitted by one or more combinations of the NDI information. , of RV and MCS.

Description

DESCRIPTION

Procedure for transmitting downlink control information

Technical field

The present invention relates to a multi-antenna communication system, and more particularly to a method for efficiently transmitting downlink control information including codeword exchange information and codeword enable / disable information .

Previous technique

The error control algorithms that are currently used in communication systems can be broadly classified into an automatic repetition request (ARQ ) scheme and a forward error correction scheme (FEC). ). The ARQ scheme includes stop and wait ARQ, N retrace ARQ, selective repeat ARQ, etc. The stop and wait ARQ refers to a scheme to confirm whether a transmitted frame has been received accurately and then transmit a subsequent frame. The N-retrace ARQ refers to a scheme for transmitting N successive data frames, and if the transmission is unsuccessful, all data frames followed by an error-generated frame are retransmitted. The selective repetition ARQ refers to a scheme to selectively retransmit only generated error frames.

On the other hand, the hybrid automatic repetition request (HARQ, hybrid ARQ) refers to an error control scheme that combines retransmission and correction of errors that maximize the coding capabilities of data error correction received during retransmission. The HARQ can be divided into HARQ with combination of packets (CC, Chase Combining) and HARQ with incremental redundancy (IR ) according to the characteristics of the bits transmitted during the retransmission. The HARQ with packet combination obtains a gain by increasing a signal-to-noise ratio (SNR ) in a receiving party using data used for primary transmission during retransmission. The HARQ with incremental redundancy obtains a coding gain in a receiving part by combining redundancy bits during retransmission to improve performance.

Figure 1 is a view that explains the concept of an ARQ stop and wait scheme in HARQ.

In an ARQ stop and wait protocol, it is determined whether data should be retransmitted by individually receiving an acknowledgment (ACK) / negative acknowledgment (NACK) signal from a receiving party after the transmission of a process block. Although the ARQ stop-and-wait scheme is the simplest and most efficient transmission procedure, the efficiency of the link transmission is reduced to a round trip time (RTT ) until a transmitting party receives the ACK signal. / NACK from the receiving party. Figure 2 is a view explaining a HARQ protocol scheme for stop and wait of N channels.

The HARQ stop and wait protocol of N channels performs N independent stop and wait HARQ operations for a time during which a transmission link is not used until it is transmitted and receives an ACK / NACK signal to overcome a described deficiency with reference to figure 1. The scheme of the HARQ protocol of stop and wait of N channels can reduce the processing delay.

On the other hand, a scheme of multiple inputs and multiple outputs (MIMO, multiple-input multiple-output) increases the capacity of the system by simultaneously transmitting multiple data streams using two or more transmitting / receiving antennas in a base station and a terminal. mobile. The MIMO scheme can obtain a transmission diversity gain or a beamforming gain using multiple transmit antennas.

A transmission diversity scheme transmits the same data through multiple transmission antennas for reliable data transmission in fast-changing channel environments and has the advantage of being achieved even without feedback information related to the channel from a receiver A beamforming scheme is used to increase a signal to interference plus noise (SINR ) ratio of a receiver by multiplying weighting values by multiple transmission antennas. In general, since a frequency division duplex (FDD ) system has independent uplink and downlink channels, high reliability channel information is required to obtain adequate beam gain and, for therefore, additional received response information from the receiver is used.

A spatial multiplexing scheme for a single user and for multiple users will be briefly described.

Figure 3 is a view illustrating the concept of spatial multiplexing and spatial division multiple access schemes used in a MIMO communication system.

Spatial multiplexing for a single user is called SM or single user (SU) -MIMO and transmits data using a plurality of antennas for a user as shown in the left part of figure 3. Therefore, the capacity of a MIMO channel increases in proportion to the number of antennas. On the other hand, spatial multiplexing for multiple users is called multiple access by spatial division (SDMA, spatial division multiple access) or multiuser (MU) -MIMO and transmits and receives data through a plurality of user antennas as shown in the right part of figure 3.

A MIMO schema includes a single codeword (SCW ) procedure that simultaneously transmits N data streams using a channel coding block and a multiple codeword (MCW ) procedure that transmits N streams. data using M channel coding blocks (M being equal to or less than N). Each channel coding block generates independent code words and each code word is designed to detect errors independently.

On the other hand, the code word described above is transmitted through one or more layers and the information transmitted through the code words can be exchanged for transmission. In a wireless communication system that can simultaneously transmit a plurality of code words, a specific code word can be disabled.

"MIMO Related DL Control Signaling", by Ericsson, 3GPP Draft, R1-080341, vol. RAN WG1, no. Sevilla, Spain, January 9, 2008, analyzes content related to multiple downlink planning assignment antennas. HARQ operations are considered for two transport blocks in spatial multiplexing mode and it is proposed to have as signaling a number of shared processes for the first and second transport blocks and that the first and second transport blocks correspond to the sub-process A and B similarly as in MIMO HSDPA. It is also commented that it should be possible to exchange the first and second transport blocks in a layer mapping with code words. The separation of the retransmission sequence number for each transport block is further analyzed.

The 3GPP document "Single codeword indication on DCI format 2", R1-082400, by Panasonic, describes PDCCH indications of code words with TBS size equal to zero using switching indications MCS, MCS RV and MCS NDI.

Divulgation

Technical problem

Therefore, the present invention has been made taking into account the above problems, and it is an object of the present invention to provide a method for efficiently transmitting downlink control information including information exchange of code words and information Enabling / disabling code words in a multi-antenna communication system.

Technical solution

The object of the present invention can be achieved by means of the methods and apparatus of the appended claims.

Advantageous effects

In a multi-antenna communication system in accordance with the embodiments of the present invention, downlink control information including codeword exchange information and word enable / disable information can be transmitted efficiently. code.

Description of the drawings

The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and, together with the description, serve to explain the principle of the invention.

In the drawings:

Figure 1 is a view explaining the concept of an ARQ stop and wait scheme in HARQ;

Figure 2 is a view explaining a HARQ protocol scheme for stop and wait of N channels;

Figure 3 is a view illustrating the concept of spatial multiplexing and spatial division multiple access schemes used in a MIMO communication system.

Figure 4 is a view illustrating a structure of a transmitting part of a MIMO system using multiple code words.

Figure 5 is a view illustrating mapping relationships between code words and physical antennas;

Figure 6 is a view explaining a multiple HARQ scheme in which m HARQ process blocks are transmitted simultaneously and an ACK / NACK signal is received for each HARQ process block;

Fig. 7 is a view explaining a method for configuring HARQ process blocks transmitted simultaneously to share HARQ process numbers;

Figures 8A and 8B illustrate the concept of transmitting null data through a specific code word according to an exemplary embodiment of the present invention;

Fig. 9 is a view illustrating the concept of transmission through the exchange of code words according to an exemplary embodiment of the present invention; Y

Fig. 10 is a view explaining the concept for discriminating between simultaneously transmitted HARQ process blocks and allowing the exchange of simultaneously transmitted HARQ process blocks and null data transmission according to an exemplary embodiment of the present invention.

Best way of realization

Reference will now be made in detail to the exemplary embodiments of the present invention, with the illustration of examples thereof in the accompanying drawings. The detailed description, which is provided below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention, instead of showing the only embodiments that can be implemented according to the invention.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without such specific details. In some cases, known structures and / or devices are omitted or shown in block diagram form, emphasizing important features of the structures and / or devices, so as not to obscure the concept of the present invention. In this specification, the same reference numbers will be used to refer to equal or similar parts.

The present invention provides a method for efficiently transmitting downlink control information including exchange information and enable / disable information of code words in a multi-antenna communication system. For this purpose, a transmission relationship of code words in a multi-antenna system, and control information generally necessary for downlink transmission will be described. Next, a method for efficiently transmitting exchange information and enabling / disabling codeword information will be described.

Figure 4 is a view illustrating a structure of a transmitting part of a MIMO system using multiple code words.

In particular, M data packets are generated as M code words by encoding (e.g., turbo encoding or turbo-encoding as shown in Figure 4) and modulation (e.g., quadrature amplitude modulation (QAM, quadrature amplitude modulation) as shown in Figure 4). Each code word has a separate HARQ process block. M modulated data symbols are coded simultaneously into a MIMO part according to a multi-antenna pattern and are transmitted through respective physical antennas. A receiving party can control a spatial multiplexing rate, a coding rate and a modulation scheme by feedback of channel quality information over a multi-antenna channel state.

For the MIMO transmission shown in Figure 4, there is necessary coding and modulation scheme (MCS ) information that is used by the transmitting party, a new data indicator (NDI ) indicating whether the data transmitted is new data or retransmitted data, redundancy version information (RV, redundancy version) relative to which sub-packet is retransmitted in the retransmission, and the like.

On the other hand, a mapping relationship between code words and physical antennas may have an arbitrary shape. Figure 5 is a view illustrating mapping relationships between code words and physical antennas.

In particular, Figure 5 illustrates the mapping of code words with layers according to a rate of spatial multiplexing in a downlink in 3GPP TS 36.211. When a spatial multiplexing rate is 1, a code word is mapped with a layer and the data generated in a layer is encoded by a pre-coding scheme so that they are transmitted through four antennas. When a spatial multiplexing rate is 2, two code words are mapped with two layers and then mapped to four antennas by a pre-encoder. For a spatial multiplexing rate of 3, one of the two code words is mapped with two layers by a serial to parallel (S / P) converter. As a result, a total of two code words are mapped with three layers and then mapped to four antennas by a pre-encoder. If the spatial multiplexing rate is 4, each of the two code words is mapped with two layers by an S / P converter. Consequently, a total of four layers with four antennas are mapped by a pre-encoder.

That is, a base station that has four transmit antennas can have a maximum of four layers and four independent codewords. However, Figure 5 illustrates a system configured to have a maximum of only two code words. Therefore, assuming that in the system shown in Figure 5, each code word has a separate HARQ process, a maximum of two independent HARQ processes can be transmitted.

On the other hand, the pre-encoder is generally expressed by a matrix of the number of transmission antennas Mt by a spatial multiplexing rate v and adaptively uses a pre-encoding matrix employing a predetermined array of matrix by a transmitter and a receiver under the circumstances. A set of said pre-coding matrices is called a codebook. The following Table 1 and Table 2 illustrate examples of a codebook used in the downlink in 3GPP TS 36.211.

Table 1

Table 2

In particular, Table 1 illustrates a codebook used in a two-antenna system (2-Tx system) and Table 2 illustrates a codebook used in a four-antenna system (4-Tx system).

On the other hand, a HARQ stop scheme and expects a receiving party data confirms whether the data has been successfully received by a code error detection, such as a cyclic redundancy check (CRC, Cyclic Redundancy Check ). For greater convenience of the description, a data unit in which an error can be detected will be referred to as "HARQ process block". An identifier used to discriminate between HARQ process blocks that can be transmitted within a predetermined range of a system, i.e., within an RTT will be referred to as "HARQ process number".

When no errors are detected in the data, a receiving party transmits an ACK signal, and when an error is detected, the receiving party transmits a signal ⁿ A ^c K. The transmitting party that receives the ACK signal, transmits the following data . The data transmitting part that receives the signal NAC ^k , retransmits the corresponding data in which an error has occurred. The retransmitted data can change its format according to a HARQ type.

If a transmission bandwidth is wide or data is transmitted using multiple antennas, a plurality of HARQ process blocks can be transmitted simultaneously.

Figure 6 is a view explaining a multiple HARQ scheme in which m HARQ process blocks are transmitted simultaneously and an ACK / NACK signal is received for each HARQ process block.

A transmitting part can simultaneously transmit m HARQ process blocks in a given transmission unit as illustrated in FIG. 6. A receiving party that has received data can transmit m ACK / NACK signals for the m HARQ process blocks to the transmitting party . Effective data transmission can be applied by combining the multiple stop and wait HARQ scheme as shown in Figure 6 with the N-channel stop and wait HARQ scheme that has been described with reference to Figure 2.

In particular, the number of combinations of HARQ process numbers that can be generated in a system that can operate a maximum of n HARQ process blocks within an RTT and simultaneously transmit m HARQ process blocks is as indicated below.

Equation 1

The number x of control signaling bits to express combinations of all HARQ process numbers is as indicated below.

Equation 2

On the other hand, if the number of HARQ process blocks transmitted simultaneously, that is, the number of simultaneously used layers is indicated by any signal, the number x of control signaling bits to express combinations of HARQ process numbers is as indicated below.

Equation 3

As a method to reduce overload of said control information, the N bits that have been used to discriminate between HARQ process identifiers in a single input scheme and multiple outputs (SIMO, single-input multiple-output) can also be used in MIMO. .

Fig. 7 is a view explaining a method for configuring HARQ process blocks transmitted simultaneously to share HARQ process numbers.

In particular, in Figure 7, a maximum of 8 HARQ process blocks can be operated during one RTT, and a maximum of 16 HARQ process blocks can be transmitted during one RTT because two layers can be used simultaneously. In Figure 7, since the HARQ process blocks transmitted simultaneously share the HARQ process numbers from 0 to 7, the HARQ process numbers can be expressed using only 3-bit control information.

For the MIMO transmission described with reference to FIG. 4, and the layer mapping, pre-coding and signaling of the HARQ process number described with reference to FIG. 5, the following control information has been commented upon for use in a 3GPP LTE system.

Table 3

However, the above form of the control information described above may have the following problems.

For example, it is assumed that a maximum of two code words can be transmitted and that a multi-antenna system has four transmit antennas. If a spatial multiplexing rate is 4, a first codeword CW1 can be transmitted through first and second layers, and a second codeword CW2 can be transmitted through third and fourth layers. In this case, an error can be detected in units of a code word. If an error is detected only in the first codeword CW1 and the codewords must be transmitted with a spatial multiplexing rate equal to 2 due to variations of the channel environments at a retransmission time point, the codeword CW1 generated by error can not use a HARQ scheme such as packet combination (CC, Chase Combining).

Furthermore, if the transmission of the second codeword CW2 is completed and, therefore, the buffer of the codeword CW2 is empty, it is difficult to deal adequately with the case in which only the codeword CW1 is transmitted. although the spatial multiplexing rate is 4.

In addition, in the sharing of a plurality of HARQ process blocks that are simultaneously transmitted in a MIMO mode by a number of HARQ processes, if the locations of the mapped data change due to the selection of an antenna or the range adaptation. During retransmission or only one unit of data is transmitted, it is not possible to recognize the HARQ process blocks only by the HARQ process number. To solve the deficiencies described above, the exemplary embodiment of the present invention proposes a method of transmitting null data to a specific code word.

Figures 8A and 8B illustrate the concept of transmitting null data through a specific codeword in accordance with an exemplary embodiment of the present invention.

In particular, Figures 8A and 8B illustrate the concept of null data transmission through a codeword, when a buffer of a codeword is empty or the spatial multiplexing rate of a channel decreases under the circumstances in which it is transmit data with a spatial multiplexing rate equal to 2 or greater between the layer mapping relationships shown in Figure 5. In Figure 8a, null data is transmitted through a code word CW1, and in Figure 8B, null data is transmitted through a code word CW2.

The above procedure apparently uses a multi-antenna pattern as if two code words were used, but in reality a spatial multiplexing rate can be set to be small due to null data. The transmission of null data through a specific codeword can be expressed as the disabling of a corresponding codeword. Disabling a specific codeword includes disabling a codeword itself (the case in which null data is transmitted) and disabling the information transmitted through each codeword. For example, Figures 8A and 8B show the disabling of the CW1 codeword itself or, however, have a concept that includes the case in which the size of a first or second transport block mapped with the code word ^c W 1 or CW2 is zero, 0.

The exemplary embodiment of the present invention proposes to interchangeably transmit locations of the code words ^c W1 and CW2.

Fig. 9 is a view explaining the concept of transmission through the exchange of code words according to an exemplary embodiment of the present invention.

In Figure 9, the exchange locations of the code words CW1 and CW2 are shown when two or more code words are transmitted between the layer mapping relationships shown in Figure 5. In the embodiment As an example of the present invention, the exchange assumes the concept that includes the case in which the information locations mapped with the code words are transmitted interchangeably, as well as the case in which the transmission locations of the codes are changed. two code words. For example, when the transport blocks are mapped with respective code words for transmission, changing the locations of the transport blocks mapped with the code words as well as changing the transmission locations of the code words themselves is included in the concept of exchange according to the present invention.

Therefore, it is proposed that the HARQ process block indexation as shown in Fig. 7 change in the following manner.

Fig. 10 is a view explaining the concept for discriminating between simultaneously transmitted HARQ process blocks and allowing the exchange of simultaneously transmitted HARQ process blocks and null data transmission according to an exemplary embodiment of the present invention.

That is, the HARQ process blocks transmitted simultaneously are discriminated by 'a' and 'b', and even during retransmission, the HARQ process blocks are discriminated by 'a' and 'b'.

When mapping each HARQ process block with a layer, it is preferable to be able to exchange the layer mapping of 'a' and 'b'.

To this end, it is proposed to transmit additional control information to discriminate between the following 6 states to a receiving party.

Table 4

In Table 4, "exchange" denotes a change of locations of transmission of code words or exchange of information mapped with respective codewords, and "Tx of nulls" denotes the transmission of null data to a codeword CWA or CWB or the disabling of a transport block mapped with each code word.

Such information may be expressed explicitly or implicitly when it is represented in a control information field. For example, the control information field can be explicitly added to express the cases in Table 4 in Table 3. When all possible cases are considered, 3-bit control information is needed to represent 6 cases.

However, since the 3-bit control information to express 6 cases is the number of bits that can represent 8 cases, the 3-bit control information can be interpreted as including some overhead in the representation of 6 cases. Therefore, it is proposed that the 6 cases in Table 4 be reduced to 4 cases in the following Table 5, thereby reducing overall overload and maintaining a similar performance.

Table 5

Specifically, Table 5 omits two cases from among the cases in Table 4 reserving the use of an exchange function when a CWA or CWB code word is disabled. That is, if some codeword is disabled, since the exchange of codeword transmission locations is less favorable than the transmission of two codewords, this exemplary embodiment proposes to reserve an exchange function when any one of the code words is disabled.

As described above, the state information of the 4 cases in Table 5 can be transmitted through explicit signaling or can be transmitted implicitly through other control information. The exemplary embodiment of the present invention proposes to indicate the exchange or no exchange using information from a 2-bit retransmission sequence (RSN) number field in Table 3. For example, an RSN field equal to 0 to indicate that the exchange is not used, and an RSN field equal to a value between 1 and 3 can be established to indicate that the exchange is performed. Alternatively, a new data indicator (NDI) of a bit and 2-bit RSN information can be set to indicate exchange or no exchange in the following manner.

Table 6

If there is a redundant state in any control information field, the necessary information can be added.

For example, if a redundant state exists in a pre-coding information presented in Table 1 above, the states indicating exchange of a CWA / CWB code word, which is necessary information, can be added to an empty state.

Table 7

The upper part of Table 7 shows Table 1 and the lower part of Table 7 shows the aggregation of a pre-coding matrix that indicates the exchange of code words to empty states of Table 1.

If there are more redundant states, other necessary information can be added.

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

Table 8

In Table 8, a field 'number of layers' and a field of pre-coding information shown in Table 1 are expressed in the same column, indexes 0 to 5 denote information for range 1, and the other indexes denote information for the rank 2. Especially, the indices of 9 to 11 denote 'A tx null' which represents that a code word A transmits null data, and the indices of 12 to 14 denote 'B tx null' which represents that a code word B transmits null data.

The exemplary embodiment of the present invention proposes a method for including an indication of whether or not an exchange occurs in the downlink control information as one bit explicit information and implicitly indicating the disabling of a word of specific code through other control information as shown in Table 8.

The following Table 9 indicates an example of the use of explicit one-bit information to indicate whether the exchange and use of the pre-coding information shown in Table 8 occurs to indicate enabling / disabling information of a word of code.

Table 9

In Table 9, the state '1' or '2' denotes a state in accordance with an explicit exchange indicator. In Table 8, the indices 6 through 14 are for layer 2 and, therefore, denote different states depending on whether the exchange occurs. Especially, the indices 9 through 14 represent that a specific code word is disabled.

As described above, the same state can have various meanings using the control information field.

As another example, if the transport formats of the first and second transport blocks of Table 3 have a meaning indicating that the size of the data is equal to 0, and the status information of the following Table 10 can be expressed as in the example of Table 9 Specifically, an explicit exchange indicator is used to indicate whether exchange and other control information occurs, that is, one or more combinations of, for example, NDI, redundancy version (RV) and MCS information, is used to indicate null transmission. Table 10

On the other hand, an indication that the transport formats of both blocks of a first transport block and a second transport block have a data size equal to 0 can be expressed using several procedures. One of them is to express a state that indicates that a data size equals 0 in a transport format field. Alternatively, the field may not be expressed when the data size equals 0. If a meaning is assigned that indicates that a first transport block is mapped with a code word CW1 and a second transport block is mapped with a word of code CW2, the transport format field of the first transport block can be eliminated to disable the code word CW1 and the transport format field of the second transport block can be eliminated to disable the code word CW2.

However, if a meaning is assigned that indicates that a data unit is transmitted to the first transport block, the size of the data can be set to be transmitted through the transport format field of the first transport block, regardless of the code word CW1 or CW2 when a unit of data is transmitted. In this case, it is assumed that the codewords CW1 and CW2 are discriminated explicitly or implicitly through any state information.

A state that indicates that a data size equals 0 can be added to the transport format fields of the first and second transport blocks. When explicit exchange information is used, four necessary states can be represented according to this exemplary embodiment.

The detailed description of the exemplary embodiments of the present invention has been provided to enable those skilled in the art to apply and practice the invention. Although the invention has been described with reference to exemplary embodiments, those skilled in the art will appreciate that various modifications and variations may be made to the present invention without departing from the scope of the invention described in the appended claims. Accordingly, the invention should not be limited to the specific embodiments described herein, but should be granted the broadest possible scope in accordance with the new principles and features described herein.

Industrial applicability

The method for transmitting control information in accordance with the exemplary embodiments of the present invention is applicable according to the same principle not only to the 3GPP LTE system described above, but also to any multi-antenna system that can simultaneously transmit a maximum of 2 code words and requires the exchange and disabling of a specific code word.

Claims (6)

A method for transmitting control information in a multi-antenna system that can simultaneously transmit a maximum of two codewords, the method comprising: transmitting modulation and coding scheme information, called MCS, a new data indicator, called NDI, and a redundancy version, called RV, for information blocks transmitted through the two code words; Y transmitting additional control information including at least one of an exchange indicator and enabling / disabling information, indicating the exchange indicator whether or not exchange occurs between the blocks of information transmitted through the two code words , and indicating the enable / disable information if any of the transmissions through the two code words is or is not disabled, in which: the exchange indicator is reserved when any one of the transmissions through the two codewords is disabled, and the exchange indicator is transmitted within downlink control information as one bit explicit information, characterized because the enable / disable information is implicitly transmitted by one or more combinations of the NDI, RV and MCS information. The method according to claim 1, wherein the additional control information indicates four states, including the four states: a first state in which the information blocks transmitted through the two code words are transmitted without exchange; a second state in which the blocks of information transmitted through the two code words are transmitted in exchange; and a third and fourth states in which one of the blocks of information transmitted through the two codewords is transmitted through a codeword enabled when any one of the transmissions through the two codewords is disabled . 3. A method for receiving control information in a multi-antenna system that can simultaneously receive a maximum of two codewords, the method comprising: receiving modulation and coding scheme information, called MCS, a new data indicator, called NDI, and a redundancy version, called RV, for information blocks transmitted through the two code words; Y receiving additional control information including at least one of an exchange indicator and enabling / disabling information, indicating the exchange indicator whether or not exchange occurs between the blocks of information transmitted through the two code words , and indicating the enable / disable information if any of the transmissions through the two code words is or is not disabled, in which the exchange indicator is reserved when any one of the transmissions through the two codewords is disabled, and in which: the exchange indicator is received within downlink control information as one bit explicit information, characterized because the enabling / disabling information is implicitly acquired by a receiving party through one or more combinations of NDI, RV and MCS information. The method according to claim 3, wherein the additional control information indicates four states, including the four states: a first state in which the blocks of information transmitted through the two codewords are transmitted without exchange; a second state in which the blocks of information transmitted through the two code words are transmitted in exchange; and a third and fourth states in which one of the blocks of information transmitted through the two codewords is transmitted through a codeword enabled when any one of the transmissions through the two codewords is disabled . 5. A user equipment for receiving control information in a multi-antenna system that can simultaneously receive a maximum of two codewords, the user equipment comprising: a receiver configured to receive modulation and coding scheme information, called MCS, a new data indicator, called NDI, and a redundancy version, called RV, for information blocks transmitted through the two code words and information of additional control that includes at least one of an exchange indicator and enable / disable information, indicating the exchange indicator if there is or is no exchange between the information blocks transmitted through the two code words, and indicating the enable / disable information if any of the transmissions through the two code words is or is not disabled, wherein the exchange indicator is reserved when any one of the transmissions through the two codewords is disabled, and wherein the receiver is further configured to receive the exchange indicator within downlink control information as one bit explicit information, characterized because the user equipment is configured to implicitly acquire the enabling / disabling information based on one or more combinations of the NDI, RV and MCS information. The user equipment according to claim 5, wherein the additional control information indicates four states, including the four states: a first state in which the blocks of information transmitted through the two code words are transmitted without exchange; a second state in which the blocks of information transmitted through the two code words are transmitted in exchange; and a third and fourth states in which one of the blocks of information transmitted through the two codewords is transmitted through a codeword enabled when any one of the transmissions through the two codewords is disabled .