KR20140103055A - Method and apparatus for power control and multiplexing for device to device communication in wirelss cellular communication system - Google Patents

Abstract

The demand for device-to-device (D2D) communication is increased with the development of various novel services in a wireless cellular communication system. When the D2D communication is employed to the cellular communication system, a terminal that performs conventional cellular communication and a terminal that performs the D2D communication exist together, thereby causing problems. When two different terminals which performs the cellular communication and the D2D communication, respectively, exist at the same time, at least one different signal is received in the reception by a base station or a terminal. And, if one received signal is greater than the other received signal by a predetermined intensity or more, the received signal having a less intensity may not be received, which is called receiving sensitivity degradation. The present invention provides a method of preventing the receiving sensitivity degradation as much as possible in the terminal which performs the conventional cellular communication by controlling transmission power of the terminal which performs the D2D communication. In addition, the present invention provides a method of multiplexing information on operations of the terminal, especially, the information on the D2D communication and the information on the cellular communication when one terminal has to perform the cellular communication and the D2D communication simultaneously.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power control and multiplexing method and apparatus for performing end-to-end communication in a wireless cellular communication system,

The present invention relates generally to a wireless mobile communication system and, more particularly, to a terminal operation including a transmission power control procedure and a multiplexing procedure of a terminal in a state where a terminal-to-terminal communication technology and a wireless cellular communication technology are mixed and used, Base station operation, and devices thereof.

As the kinds of services using the wireless mobile communication system have diversified, there has been a need for a new technology to more efficiently support new emerging services, and new methods and new technologies have been developed in the wireless mobile communication system .

BACKGROUND ART [0002] In a new technology in which a device to device (D2D) communication is emerging as a solution to a new service, a terminal-to-terminal communication is basically a technology that allows a terminal to directly communicate with another terminal existing around the terminal to be. When the terminal-to-terminal communication technology is used, the terminal discovers which terminals are present around the terminal, and can perform direct communication with the terminal requiring communication.

When the terminal-to-terminal performs direct communication, relatively few radio resources are used compared to the communication using the existing radio network using the base station, which is a great advantage in terms of radio resource efficiency. In addition, since a method of finding a terminal around the terminal is supported, the terminal can directly provide necessary information to a desired terminal, thereby supporting the advertisement service and the social networking service (SNS) .

Currently, LTE-A (Long Term Evolution - Advanced) systems require support for end-to-end technology and technical discussions are in progress.

1 is a diagram showing a state in which terminal-to-terminal communication is supported in a cellular system.

A base station 101 manages a terminal 103 and a terminal 104 in a cell 102 managed by the base station. The terminal 103 performs cellular communication using the link 106 between the base station 101 and the terminal-base station, and the terminal 104 performs cellular communication using the link 107 between the base station 101 and the terminal-base station do. When terminal-to-terminal communication is possible between the terminal 103 and the terminal 104, information can be exchanged directly using the terminal-to-terminal link 105 without going through the base station 101.

It is assumed that a device to device (hereinafter referred to as D2D) technology using a cellular wireless mobile communication system such as the LTE-A system is basically implemented in a direction that does not cause a greatest damage to a terminal using an existing cellular system do. For this purpose, a resource that does not overlap with the radio resources used by the cellular terminal (in the present invention, the cellular terminal refers to a terminal performing existing terminal-to-base station communication, not terminal-to-terminal communication) may be used for D2D communication , Or that the resources used by the cellular terminal are used by the D2D terminal equally, but not so much as to interfere with each other as much as possible.

There is a Frequency Division Duplexing (hereinafter referred to as FDD) as a reverse and forward Duplexing method used by an LTE or LTE-A system.

The FDD distinguishes between forward and reverse directions by using different frequency resources. When the D2D communication is used differently from the existing cellular communication resources in the system using the FDD, a method of using the reverse frequency resource as the D2D among the forward and reverse resources tends to be a higher priority. This is because, in the FDD system, more kinds of signals are multiplexed in the forward frequency resource than in the reverse frequency resource, so it is difficult to allocate the resources separately for the D2D communication as compared with the reverse resource.

Also, in the FDD system considering only existing cellular terminals, the forward traffic tends to be higher than the reverse direction due to the characteristics of the communication service, and the overhead transmitted in the forward direction is larger than the reverse direction, It is generally larger than the frequency usage burden on the resource.

Therefore, if a forward resource is allocated for D2D communication, the burden on the forward resource becomes larger, which may make it difficult to balance the use of forward and reverse frequency resources.

Assuming that the D2D communication is performed using the reverse resource in the communication system using the FDD, the problem caused by using the forward resource in the D2D technique described above can be solved. However, applying D2D communication technology using reverse resources does not solve all the problems. For example, in the reverse resource used in the LTE system, resources of arbitrary size may be allocated to both ends of the entire band for transmission of control information for a conventional cellular terminal.

The control information transmitted in the reverse direction includes forward link channel state information (CQI) of the UE, ACK / NACK information as response information for a Hybrid Automatic ReQuest (HARQ) Scheduling request information for uplink information transmission, and the like.

 The control information is transmitted from any of the terminals to the BS in the reverse direction. The transmission of the control information may occur even when only the cellular terminals perform communication with the reverse resource, and also when the D2D terminals communicate between the terminals. That is, a plurality of D2D terminals communicate with each other at the same time (for example, in the same subframe in LTE) in the same cell, and the cellular terminal transmits control information to the base station. The case where the frequency resource used for the control information transmission and the frequency resource used for the communication between the terminals of the D2D terminal are different from each other may be assumed.

2 is a diagram showing a state in which a cellular terminal in the same cell and a D2D terminal simultaneously transmit and receive signals to and from a base station using reverse resources in the same subframe.

The base station 201 has cells and the terminals 203, 205, 206 are located in the cell. The terminal 203 transmits the reverse control information to the cellular terminal using the reverse resource 204. The terminal 205 is performing D2D communication with the terminal 206, and the terminal 205 can transmit information to the terminal 206 using the D2D link 207. [ At this time, the terminal 203 appropriately sets the transmission power for information transmission so that the base station 201 can have a proper reception power in receiving the uplink control information. Also, the terminal 205 appropriately sets the transmission power for information transmission so that the terminal 206 can receive the proper reception power when the terminal 206 receives the D2D transmission.

In this case, as the distance between the terminal 205 and the terminal 206 increases, the terminal 205 may set a large transmission power to perform the D2D transmission so that the terminal 205 can be properly transmitted. At this time, if the terminal 205 is located very close to the base station 201, the D2D transmission transmitted from the terminal 205 to the terminal 206 may be received at the base station 201 with a very large received power.

At this time, when the reception power received from the terminal 205 by the base station 201 becomes larger than a predetermined value (refer to 208) in comparison with the signal transmitted by the cellular terminal 203 in the reverse direction, desensitization of receiving sensitivity occurs upon receiving the signal, There is a possibility that reception of the reverse control information transmitted by the base station 201 to the base station 201 may become impossible.

In the above case, when a cell terminal included in one base station and a D2D terminal perform simultaneous transmission using reverse frequency resources, a difference between the strengths of the received signals received from the cellular terminal and the D2D terminal becomes large, so that the information transmitted from the cellular terminal The problem that can not be received is described. In the present invention, a power control procedure of a D2D terminal and an operation of a related base station and a terminal for solving a problem due to a lack of reception sensitivity phenomenon in the scenario described above will be described.

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the above problems, and it is an object of the present invention to provide a D2D channel which is required for performing communication at the same time without causing deterioration of reception sensitivity between a terminal using a D2D technology and a cellular terminal A power control procedure, a procedure in which one terminal simultaneously transmits D2D data and cellular data, and a method and apparatus for operating the base station and the terminal to support the above procedures.

According to an aspect of the present invention, there is provided a method of controlling power of a terminal for terminal-to-terminal communication in a wireless communication system, the method comprising: receiving power control- Determining transmission power of the terminal based on available power and power control related information for the received terminal-to-terminal communication; and transmitting data according to the determined transmission power.

Also, in the wireless communication system of the present invention, a terminal for controlling power for terminal-to-terminal communication includes a transmitter / receiver for transmitting / receiving signals to / from a terminal or a base station, and power control- Determining a transmission power of the terminal based on the maximum available power of the terminal and the power control related information for the received terminal to terminal communication and controlling the transmission of data according to the determined transmission power .

Meanwhile, a power control method for a terminal for terminal-to-terminal communication in a wireless communication system according to another embodiment of the present invention includes receiving transmission-related information for the terminal-to-terminal communication from a base station, , Determining whether the transmission sub-frame of the cellular information to be transmitted to the base station is a sub-frame permitting the UE-to-terminal communication, and if the transmission sub-frame of the cellular information is a sub- Determining a transmission power using a first offset value included in the transmission related information, and transmitting the cellular information to the base station according to the determined transmission power.

In addition, in a wireless communication system according to another embodiment of the present invention, a terminal for controlling power for terminal-to-terminal communication includes a transmission / reception unit for transmitting / receiving signals to / from a terminal or a base station, Frame based on the transmission-related information, and determines that the transmission sub-frame of the cellular information to be transmitted to the base station is a sub-frame permitting the UE-to-terminal communication. If it is determined that the transmission sub- Frame determining unit determines a transmission power using a first offset value included in the transmission related information and controls the transmission of the cellular information to the base station according to the determined transmission power .

In addition, in the method of multiplexing a terminal for terminal-to-terminal communication in a wireless communication system according to another embodiment of the present invention, transmission of uplink control information including ACK or NACK for forward information reception at a certain point Determining whether information included in the uplink control information is an ACK or NACK when transmission is required, and if the information included in the uplink control information is ACK, determining whether the information included in the uplink control information is ACK or NACK, And transmitting the uplink control information to the base station without transmitting information on communication.

In addition, in a wireless communication system according to another embodiment of the present invention, a terminal for multiplexing cellular information and terminal-to-terminal communication information includes a transceiver for transmitting / receiving signals to / from a terminal or a base station, ACK or NACK, and determines whether information included in the uplink control information is an ACK or a NACK when transmission is required. If it is determined that the information included in the uplink control information is ACK or NACK, The base station controls to transmit the uplink control information to the base station without transmitting information on the terminal-to-terminal communication.

According to the embodiment of the present invention, it is possible to prevent a situation in which the reception sensitivity degradation phenomenon occurs to the terminal performing the existing cellular communication by controlling the transmission power of the terminal performing terminal-to-terminal communication. According to another embodiment of the present invention, the operation of a terminal in a case where one terminal simultaneously performs cellular communication and terminal-to-terminal communication can be clearly defined.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.
2 is a diagram illustrating an example of a reverse frequency resource
FIG. 3 is a flowchart illustrating an autonomous cell deactivation process according to an embodiment of the present invention; FIG.
4 is a flowchart illustrating an operation procedure of a small cell for performing a network control cell deactivation procedure according to an embodiment of the present invention.
5 is a block diagram illustrating an internal structure of a transmitter device of a D2D terminal according to an embodiment of the present invention;
6 is a block diagram illustrating an internal structure of a base station apparatus for power control of a D2D terminal according to an embodiment of the present invention;
FIG. 7 is a flowchart showing an operation sequence of a terminal according to an embodiment of the present invention; FIG.
8 is a flowchart showing an operation procedure of a base station according to an embodiment of the present invention; 9 is a block diagram illustrating an internal structure of a terminal according to another embodiment of the present invention.
10 is a block diagram showing an internal structure of a base station according to another embodiment of the present invention;
11 is a flowchart showing a multiplexing operation procedure of a terminal according to an embodiment of the present invention.
FIG. 12 is a flowchart showing a procedure of multiplexing operations of a terminal according to another embodiment of the present invention; FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

While the embodiments of the present invention will be described in detail, the OFDM-based wireless communication system, particularly the 3GPP EUTRA standard, will be the main object of the present invention, but the main point of the present invention is to provide a communication system It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

In the embodiment of the present invention described below, a base station or a cell can be used in the same sense. Also, D2D communication can be used to include both a discovery operation for finding neighboring terminals and a direct communication in which the terminals and the terminals exchange information directly.

In the above description, when the FDD system is assumed as the duplexing method to which the present invention is applied, the D2D communication is supported using the reverse frequency resource.

FIG. 3 is a diagram showing resources that can be used as D2D by using the format of the reverse resource supported by the current LTE.

In FIG. 3, reference numeral 301 denotes a plurality of subframes gathered along the time axis. The subframe is a time unit used in LTE, which is a 10 ms time interval including a plurality of symbols. In the present invention, a subframe used in LTE is taken as an example, but the present invention is not limited thereto. have.

In the present invention, it is assumed that a part of the set 301 of subframes is used as a resource for D2D. 3, regular subframes 302 are allocated for cellular communication and D2D subframes 303 are allocated for D2D communication.

In detail, the resource of D2D subframes 303 may include a plurality of subframes in the D2D reverse resource. One subframe includes a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols or a single-Carrier Frequency Division Multiplexing (SC-FDM) symbol on a time axis and includes a plurality of subcarriers along the frequency axis.

As described above, among the subcarriers available in the frequency domain in the LTE reverse resource, as shown in 304 and 305 of FIG. 3, a plurality of subcarriers located at both ends are called reverse control information (in the LTE, Control Channel (PUCCH)). As described above, the uplink control information includes uplink channel quality information (CQI) of the UE, ACK / REQ response information for a Hybrid Automatic ReQuest (HARQ) NACK information, and Scheduling Request information for transmission of reverse information.

On the other hand, D2D transmission is possible through a plurality of subcarriers 306 located in the middle of the frequency axis excluding both ends of the subframe. At this time, the last OFDM symbol (or SC-FDM symbol) located in each subframe can be used for transmission of a sounding reference signal (SRS) required for channel estimation in the reverse direction of the UEs in the base station. Since the period of transmission of the SRS varies depending on the setting of the base station, there may be a sub-frame including the SRS and a sub-frame not including the SRS. In the subframe without SRS, the last symbol 307 can be used as a resource for D2D. In addition, due to the nature of D2D, the UE needs to continuously transmit and receive. In this case, The last symbol 307 may be used as the transition time needed to change the operation to transmit.

2, the terminal 205 located close to an arbitrary base station 201 may use the D2D communication channel 207 (see FIG. 2) If another cellular terminal 203 transmits the PUCCH 204 to the base station 201 in a situation where the mobile terminal 203 transmits data using the D2D resource to the remote terminal 206, the base station 201 transmits the PUCCH 204 to the terminal 203 The PUCCH 204 can not be correctly received. This is because the reception strength of one or more signals received by one base station 201 may differ by more than a predetermined value. That is, when the signal 208 transmitted from the terminal 205 arrives at the base station 201, the reception intensity may become very high. The present invention provides a method for solving the above-mentioned situation in which a base station does not receive information of a cellular terminal due to communication of a D2D terminal through the following embodiments.

First, before explaining the transmission power control shown in the present invention, a transmission power control method in a case where a transmitter and a receiver communicate in general, and in particular, a transmitter is a terminal will be described. The transmit power used by a terminal to transmit an arbitrary channel to a base station can be set to a smaller value among the following two variables.

1. Maximum available power of transmitter (terminal)

2. When the receiver (base station) receives the signal transmitted by the transmitter (terminal), the transmit power

Here, the maximum available power of the transmitter, i.e., the terminal may be the power that can be physically used by the transmitter to limit the transmission of information by the hardware of the terminal or may be the maximum power determined by an arbitrary setting of the base station . The receiver, that is, the base station makes an effort to adjust the received power of the terminal to a predetermined value. This is to prevent reception sensitivity degradation when signals of several terminals are simultaneously received, and to facilitate scheduling for transmission of the terminal will be. Therefore, the terminal limits the transmission power to match the reception power of the base station.

Therefore, the transmission power of the UE can be determined by the above two parameters, and the transmission power of the UE can be expressed by the following equation.

Tx_Power = min {Max_Tx_Power, f (Rx_Power)}

In the above equation, Tx_Power is the transmission power of the UE, Max_Tx_Power is the maximum available power of the UE, Rx_Power is the reception power of the base station receiving the transmission signal of the UE, and the function f (Rx_Power) And the transmission power determined accordingly. The function f (Rx_Power) can be variously determined using the Rx_Power value, and the most representative formula is as follows.

f (Rx_Power) = Rx_Power + Prop_loss

In the above, Prop_loss is a path loss according to the distance between a transmitter and a receiver, and is determined by a state where a transceiver is located as well as a distance between transceivers, a medium existing between the transceivers, and the like. The UE measures the received power of the reference signal transmitted from the base station and measures the transmission power of the reference signal from the base station so that the terminal can recognize the path loss value of the base station and the base station. Since the path loss value is a value measured over a long term and it can be assumed that the path loss in the reverse direction and the forward path are the same, the path loss value measured in the forward direction can be used for the power control of the reverse transmission .

The f (Rx_Power) equation can be defined using various parameters in addition to the path loss value. The above variables can be exemplified by the amount of resources of the channel to be transmitted (for example, the number of PRB (physical resource blocks) defined in LTE), an arbitrary offset value set by the base station, and various other variables. The above equation f (Rx_Power) can be obtained by adding arbitrary weights to the respective variables and adding them together. The weight can be changed, and it can be set by the base station, and it can be a positive value or a negative value.

A method for solving the problem of lowering the base station reception sensitivity through power control of the D2D terminal will be described below through various embodiments.

Example 1: D2D  Channel power control

In the present embodiment, a terminal performing D2D communication refers to the D2D link (in the present invention, a link means a radio channel through which information is transmitted between a transmitter and a receiver and can be used in the same sense as a radio link, a channel, a radio channel, The present invention proposes a method of supporting both information transmission through the D2D link and resolution of reception sensitivity degradation of the base station through proper setting of the transmission power for the D2D link.

There is an arbitrary base station and a cellular terminal, and the cellular terminal transmits arbitrary control information or data information to the base station, and the D2D terminal existing in the base station at the same time or the same subframe transmits the D2D channel The transmission power of the D2D terminal can be set to any one of the following three parameters. According to a preferred embodiment of the present invention, the transmission power of the D2D terminal can be set to the smallest value among the three parameters.

1. The maximum available power of the transmitting D2D terminal (205 in FIG. 2)

2. When the receiving D2D terminal (206 in FIG. 2) receives the signal transmitted from the transmitting D2D terminal (205 in FIG. 2), the transmission power that can be set to the desired receiving power

3. When the base station (201 in FIG. 2) receives a signal transmitted from the transmitting D2D terminal (205 in FIG. 2), the base station receives a signal from another cellular terminal (203 in FIG. 2) The transmission power enough not to cause the phenomenon

The maximum usable power of the terminal may be the physically usable power that the transmitter is limited by the hardware of the terminal for transmitting information or it may be the maximum power determined by an arbitrary setting of the base station. The reason why the transmitting D2D terminal makes an effort to match the D2D channel transmitted by the receiving D2D terminal with the proper receiving power is to facilitate the scheduling of the transmission of the transmitting D2D terminal. The third parameter is a condition that when the base station receives the D2D transmission transmitted from the transmitting D2D terminal, the receiving power of the D2D transmission is maintained at a predetermined level or lower, It is a value which is not enough. In this case, the third variable prevents the reception signal of the D2D terminal from becoming too large at the base station, thereby reducing the receiving sensitivity of the signal of the living cell terminal. The above contents can be expressed by the following equations.

Tx_Power = min {Max_Tx_Power, f (Rx_Power_D2D), g (Rx_Power_eNB)}

Rx_Power_D2D is the reception power of the receiving D2D terminal that receives the transmission signal of the transmitting D2D terminal, Rx_Power_2NB is the reception power of the transmitting D2D terminal, and Rx_Power_2NB is the transmission power of the transmitting D2D terminal. In the equation, Tx_Power is the transmission power of the transmitting D2D terminal, Max_Tx_Power is the maximum available power of the transmitting D2D terminal, And may be the received power when the base station receives the transmitted signal.

The function f (Rx_Power_D2D) is the transmission power determined by the transmitting D2D terminal when the Rx_Power_D2D is determined, and the function g (Rx_Power_eNB) is the transmission power determined by the transmitting D2D terminal when the Rx_Power_2NB is determined.

The function f (Rx_Power_D2D) can be determined in various ways using the value of Rx_Power_D2D. The most representative equation may be as follows.

f (Rx_Power_D2D) = Rx_Power_D2D + Prop_loss_D2D

In the above, Prop_loss_D2D is a path loss according to the distance between the transmitting D2D terminal and the receiving D2D terminal, and is determined by the state where the transceiver is located as well as the distance between the transceivers and the medium existing between the transceivers. The transmitting D2D terminal can know the path loss by transmitting and receiving arbitrary promised signals and sharing information about the transmission power of the promised signal when the transmitting D2D terminal and the receiving D2D terminal set the D2D channel.

The above equation f (Rx_Power_D2D) can be defined using various parameters in addition to the path loss value. These variables include the amount of resources of the channel to be transmitted (for example, the number of PRBs (Physical Resource Blocks) defined in the LTE), an arbitrary offset value set by the base station or set through the channel setting between D2D terminals, An example is a branch variable. The above equation f (Rx_Power_D2D) can be obtained by adding arbitrary weights to the respective variables and adding them together. The weight may be changed, and may be set by the base station or may be set between the D2D terminals through channel setting, and may be a positive value or a negative value.

The function g (Rx_Power_eNB) can be defined in various ways using the Rx_Power_eNB value. The most typical formula is as follows.

g (Rx_Power_eNB) = Rx_Power_eNB + Prop_loss_eNB + Desense_Offset

Prop_loss_eNB is the path loss according to the distance between the transmitting D2D terminal and the base station. It is determined by the state where the transmitting D2D terminal and the base station are located as well as the distance between the transmitting D2D terminal and the base station, the medium existing between the transmitting D2D terminal and the base station The transmitting D2D terminal can measure the receiving power of the reference signal transmitted by the base station and measure the transmission power of the reference signal from the base station to know the path loss value of the transmitting D2D terminal and the base station.

The desense offset (Desense_Offset) may be defined as a value that adjusts the reception sensitivity so as not to lower the reception sensitivity when the base station receives the D2D signal and the signal coming from another cellular terminal. The desense offset (Desense_Offset) may be determined to an arbitrary value in consideration of the performance of the receiver of the base station, and may be set by the base station and informed to the transmitting D2D terminal.

The equation g (Rx_Power_eNB) can be defined using various parameters in addition to the path loss value. The variables include, for example, the amount of resource of the D2D channel to be transmitted (for example, the number of PRB (physical resource blocks) defined in LTE), an arbitrary offset value set by the base station, and various other variables. g (Rx_Power_eNB) can take the form of adding arbitrary weights to each variable and adding them together. The weight can be changed, and it can be set by the base station, and can be a positive value or a negative value.

Hereinafter, an operation flowchart of a terminal and a base station according to the first embodiment of the present invention will be described.

FIG. 4 is a flowchart illustrating a transmission power control process of the D2D channel transmitted by the D2D terminal.

4 shows a transmitting D2D terminal 401, a receiving D2D terminal 402 and a base station 403. The transmitting D2D terminal 401 and the receiving D2D terminal 402 set D2D (or a channel for D2D communication) in operation 404. Information of the base station may be used in step 404. For example, the D2D transmitting / receiving terminals need to perform mutual synchronization in order to discovery each other and perform data scheduling and actually transmit data. The synchronization may be performed using a synchronization signal (PSS, SSS) .

Subsequently, the transmitting D2D terminal 401 receives the power control related information from the base station 403 in step 405. The power control related information may include information used when determining f (Rx_Power_D2D) or information used when determining g (Rx_Power_eNB) in the above equation. The receiving D2D terminal of 402 can also receive the power control related information from the base station of 403 in step 406. [ This is because the receiving D2D terminal of the 402 can also be a transmitting D2D terminal for the D2D channel. The power control related information of step 406 does not necessarily have to be the same as the power control related information of step 405. [

In FIG. 4, the base station for providing power control related information to the transmitting D2D terminal 401 and the base station for providing the power control related information to the receiving D2D terminal 402 are the same base station 403. However, the present invention is not limited thereto. For example, May be different from each other if the base station to which the base station belongs is a different base station.

The transmitting D2D terminal 401 and the receiving D2D terminal 402 can then determine the path loss for the D2D channel. The determination of the path loss may be predetermined in step 404. The determination of the path loss may be shared between the transmitting D2D terminal 401 and the receiving D2D terminal 402 through path loss calculation and measurement report according to the reference signal transmission in step 407 and the measurement of the reference signal in step 408. [ The transmitting D2D terminal 401 stores the information held therein and the following equation

Tx_Power = min {Max_Tx_Power, f (Rx_Power_D2D), g (Rx_Power_eNB)}

In step 409, the D2D channel can be transmitted.

5 is a block diagram illustrating an internal structure of a transmitting D2D terminal according to an embodiment of the present invention.

The storage unit 501 may store information used to determine power control related setting values received from the base station, that is, information used to determine f (Rx_Power_D2D) or g (Rx_Power_eNB).

The power control related information stored in the storage unit 501 is input to the power control controller 502. The power control controller 502 determines the transmission power of the D2D channel using the above equation and transmits the power control information to the power amplifier through the control signal 503 Input the transmission power.

Meanwhile, in the D2D channel generator 504, a signal transmitted through the D2D channel is generated by wirelessly transmitting information through channel coding, modulation, and the like. The signal is amplified by a power amplifier 505. At this time, the power control controller 502 determines the degree of amplification using the control signal 503. The signal amplified by the power amplifier 505 is wirelessly transmitted through the transmitter 506.

Although the power controller 502 and the D2D channel generator 504 are shown as separate blocks in the above description, they need not necessarily be divided into hardware that is physically divided as described above, but may be implemented with detailed functional blocks performed by the controller.

6 is a block diagram illustrating an internal structure of a base station apparatus for power control of a D2D terminal according to an embodiment of the present invention.

The D2D power control related setting value determiner of the base station determines a power control related setting value required when the D2D terminal receives the D2D channel (601). The power control related set value may include information used when determining f (Rx_Power_D2D). In addition, the D2D power control related setting value determiner of the base station determines a power control related setting value required when the base station receives the D2D channel (602). The power control related set value may include information used when determining g (Rx_Power_eNB).

The two setting values are signaled to the D2D terminal through the transmission unit 603. [ The procedure for signaling is shown in step 405 of FIG. 6, the D2D power control-related set value determining unit is divided into two blocks. However, the D2D power control-related set value determining unit need not necessarily be divided into the hardware that is physically divided as described above, and may be implemented with detailed functional blocks performed by the controller Be careful.

Example 2: D2D  If a channel exists Cellular  Channel power control

In the second embodiment of the present invention described below, a new power control method of a cellular terminal is proposed in order to solve a problem of a decrease in reception sensitivity of a cellular terminal due to the reception of a D2D link of a D2D terminal existing at a position adjacent to the base station.

In the above description, when the cellular terminal transmits information using the cellular channel in the reverse direction, the transmission power is used as a value determined according to the following equation.

Tx_Power = min {Max_Tx_Power, f (Rx_Power)}

In the above equation, Tx_Power is the transmission power of the UE, Max_Tx_Power is the maximum available power of the UE, Rx_Power is the reception power of the base station receiving the transmission signal of the UE, and the function f (Rx_Power) And the transmission power determined accordingly.

In this embodiment, the cellular terminal provides a method of setting the transmission power using another equation according to the presence or absence of the D2D terminal.

That is, when there is a D2D terminal in the vicinity of a base station and the base station receives the transmission of the cellular terminal, it is possible to prevent a problem of a decrease in reception sensitivity due to the D2D terminal, And adding the offset to transmit with a stronger transmission signal. The present embodiment according to the above description can be expressed by the following equation.

Tx_Power = min {Max_Tx_Power, f (Rx_Power) + offset_D2D}

In the above equation, Tx_Power is the transmission power of the UE, Max_Tx_Power is the maximum available power of the UE, Rx_Power is the reception power of the base station receiving the transmission signal of the UE, and the function f (Rx_Power) And can be the transmission power determined accordingly. Lastly, the offset_D2D variable is an offset having a different value according to the presence or absence of a D2D terminal that performs simultaneous transmission with the cellular terminal when the cell terminal transmits arbitrary data information or control information.

Generally, a larger offset_D2D value can be set in comparison with the case where there is a D2D terminal transmitting simultaneously. For example, if there is a D2D terminal, offset_D2D (first offset) = 5dB, and if there is no D2D terminal, offset_D2D (second offset) = 0dB.

In addition, the offset_D2D effect can be obtained by setting the variable in f (Rx_Power) to be different. The f (Rx_Power) expression of PUCCH can be set as follows.

등의 변수가 상위 계층에서 PUCCH 성능을 위하여 설정해주는 변수들인데, 이 변수 중 하나 혹은 복수개의 변수들을 두 개의 셋으로 구분하여 D2D가 설정되지 않은 일반 서브프레임에서 사용되는 하나의 셋과, D2D가 설정된 서브프레임에서 사용되는 다른 하나의 셋을 설정하여 준다. 단말은 현재 PUCCH를 전송하는 서브프레임에서 D2D가 존재하는 지의 여부를 판단하여 설정된 두 개의 변수, 혹은 변수 셋 중에서 하나를 선택하여 상기 수학식에 대입하여 PUCCH 전력 설정에 사용할 수 있다.here

Are set for the PUCCH performance in the upper layer. One set used in the normal subframe in which one or more of the variables are divided into two sets and D2D is not set, and D2D And sets another one to be used in the set subframe. The UE may determine whether D2D exists in a subframe in which the PUCCH is currently transmitted, and may select one of two set variables or a set of variables to be used in the PUCCH power setting.

The offset_D2D value may be set by the base station through signaling, or may be set to an arbitrary value. Alternatively, a new DCI format may be defined in addition to a conventionally set format of DCI (Downlink Control Information), and the offset_D2D value may be informed to the UE through a newly defined DCI format. For example, the offset_D2D value may be transmitted to the UE through a physical downlink control channel. Alternatively, the information may be transmitted to the terminal using a reserved field in any of the previously defined DCI formats without defining a new DCI format, and may be defined to have different interpretations for arbitrary fields of the previously defined DCI format And transmit the offset_D2D value to the terminal.

On the other hand, the function f (Rx_Power) in the above equation can be determined by the method described above.

On the other hand, the base station can inform all terminals belonging to the base station of the subframe in which the D2D channel exists by using the system information, so that the cellular terminal can know whether or not the D2D terminal is simultaneously transmitted. In addition, the base station may inform each terminal of the transmission time of the D2D terminal, and may inform the terminal through higher layer signaling or physical layer control information.

Hereinafter, the operation procedure of the terminal and the base station according to the second embodiment of the present invention will be described. 7 is a flowchart showing an operation procedure of a terminal according to the second embodiment of the present invention.

The cellular terminal starts operation in step 701 and acquires D2D transmission related information, for example, information on when the D2D transmission is performed through which subframe and offset_D2D information according to the D2D transmission.

The information on the subframe in which the D2D transmission is performed can be used to determine in which subframe each of the offset_D2D information A and B received by the terminal is to be used.

Assuming that offset_D2D = A when the D2D terminal exists and offset_D2D = B when the D2D terminal does not exist, the value for (A, B) is related to the offset_D2D information according to the D2D transmission, Can be set.

The D2D transmission related information can be obtained from the system information through a broadcast channel, and the base station can set and inform each terminal. In this case, higher layer signaling such as RRC may be used.

The offset_D2D information can be obtained from the system information. Alternatively, the base station can notify offset_D2D information for each terminal. In this case, higher layer signaling such as RRC may be used. Alternatively, the base station may define a new DCI format including the D2D transmission related information and offset_D2D information, and the base station may transmit the new DCI format to the terminal through the PDCCH. Alternatively, the base station may not define a new DCI format, and may transmit the information to the terminal using a reserved field in any of the previously defined DCI formats. Also, the offset_D2D value may be transmitted to the UE by defining the arbitrary field of the previously defined DCI format to have different interpretations.

In step 703, the cellular terminal prepares cellular information, that is, information to be transmitted to the base station. Next, in step 704, it is determined whether D2D transmission is performed at the time of transmitting the cellular information using the D2D transmission related information acquired in step 702 . For example, the UE can determine whether the subframe for transmitting the cellular information is a subframe for allowing D2D transmission.

As a result of the determination, if the D2D transmission is performed together, the terminal proceeds to step 705 and sets an offset value required when offset_D2D = A, i.e., when there is a D2D transmission. On the other hand, if the D2D transmission is not performed together, the terminal proceeds to step 706 and sets an offset value required when offset_D2D = B, that is, when there is no D2D transmission.

Then, the MS calculates an offset_D2D value set in step 707,

Tx_Power = min {Max_Tx_Power, f (Rx_Power) + offset_D2D}

To determine the transmission power.

In step 708, the terminal transmits the cellular information using the transmission power, and then ends the transmission procedure in step 709.

8 is a flowchart showing an operational procedure of a base station according to the second embodiment of the present invention.

The base station starts operation in step 801 and transmits information on D2D transmission related information, that is, information on when the D2D transmission is performed through which subframe, in step 802. In step 803, the base station transmits all information related to the power control of the cellular terminal including the power control information of the cellular terminal, i.e., offset_D2D information.

The terminal can obtain the D2D transmission related information from the system information through a broadcast channel, and the base station can also inform the terminal about the D2D transmission related information. Similarly, the UE can know the offset_D2D from the system information, or the BS can set and inform the UE on a per-UE basis. In another embodiment, a new DCI format including the D2D transmission related information and the offset_D2D information may be defined, and the base station may transmit the new DCI format to the mobile station through the PDCCH. Alternatively, the information may be transmitted to the terminal using a reserved field in any of the previously defined DCI formats without defining a new DCI format, and may be defined to have different interpretations for arbitrary fields of the previously defined DCI format And transmit the offset_D2D value to the terminal.

In operation 804, the operation is completed.

FIG. 9 is a block diagram showing an internal structure of a terminal device for an embodiment according to the second embodiment of the present invention.

The D2D transmission determination unit 901 determines whether there is a D2D transmission. The power control related set value storage 902 stores power control related set values received from the base station. When the determination information of the D2D transmission determination unit 901 and the information stored in the power control related setting value storage 902 are inputted to the cellular transmission power controller 903, the transmission power for the cellular information transmitted by the terminal is determined.

The offset_D2D value is stored in the power control related set value storage 902. In accordance with the determination of the D2D transmission determination unit 901, the cell transmission power controller 903 determines the correct offset_D2D. The channel to be transmitted by the UE is generated in the cell channel generator 905 and amplified through the power amplifier 906. The amplified value is determined by inputting (904) the value determined in the cellular transmission power controller 903 to the power amplifier 906. The amplified cellular information is transmitted through the transmitter 907.

Each block shown in FIG. 9 is not necessarily divided into physically separated hardware, but may be implemented with detailed functional blocks performed by the control unit.

10 is a block diagram showing an internal structure of a base station apparatus according to a second embodiment of the present invention.

The D2D transmission related information generated by the D2D transmission time information generator 1001 and the cellular channel transmission power control related information generated by the cellular transmission related information generator 1002 are transmitted to the terminal through the transmission unit 1003.

Hereinafter, a method of multiplexing D2D information and cellular information provided in another embodiment of the present invention will be described.

A description has been given of a problem in a situation where a cellular terminal transmits cellular information in a reverse direction to a base station and a D2D terminal transmits to another D2D terminal using the same reverse frequency resource and a solution through power control of a D2D terminal or a cellular terminal .

Hereinafter, it is assumed that one terminal transmits or receives D2D information and transmits cellular information at the same time. The UE may perform normal cellular transmission in which reverse data information is transmitted in the reverse direction (i.e., to the base station) or in the reverse direction according to the forward data information according to the scheduling of the base station. Incidentally, it may happen that transmission or reception of D2D information for D2D together with the cellular transmission is required at the same time.

The cellular transmission may include data transmission, and may also include ACK / NACK transmission, CQI transmission, and scheduling request information according to forward data transmission.

In another embodiment of the present invention described below, a solution for the case where the transmission of the cellular information and the transmission and reception of D2D information occur simultaneously is proposed.

Example 3: Cellular  Channel and D2D  Send channels simultaneously

In this embodiment, it is assumed that one terminal transmits reverse cell information to a base station over a cellular channel and simultaneously transmits D2D information to another D2D terminal through a D2D channel. The UE uses a single carrier frequency division multiple access (SC-FDMA) transmission scheme.

Therefore, it is assumed that a channel transmitted by one terminal is limited to one channel. In the case where the terminal needs to simultaneously transmit the cellular channel and the D2D channel, the following operation is possible. Preferably, one of the operations described below can be selected and performed.

1. Send only the D2D channel.

2. Send only the cellular channel.

(In this case, the base station transmits the D2D channel and the cellular channel through the upper layer signaling such as system information, RRC signaling, or the physical layer control information, etc.) according to the setting of the base station. When the simultaneous transmission and reception of a channel occurs, information on which channel is to be given priority can be transmitted to the terminal.

4. Ignore the SC-FDMA scheme and transmit both channels simultaneously. At this time, the transmission power is first allocated to the cellular channel and the remaining transmission power is allocated to the D2D channel.

Example 4: ACK / NACK In accordance Cellular  Channel and D2D  Selective channel transmission

In this embodiment, it is assumed that one mobile station transmits reverse cellular information including ACK / NACK to a base station through a cellular channel, and simultaneously transmits D2D information to another D2D terminal through a D2D channel.

The fact that the UE transmits ACK / NACK information to the Node B means that the UE informs the Node B whether ACK / NACK has been correctly received with respect to the forward information already received.

When the information to be transmitted to the base station by the terminal is an ACK of ACK / NACK, that is, when forwarding information is correctly received, ACK information must be transmitted to the base station to prevent further retransmission. On the other hand, when the information to be transmitted to the Node B by the UE is a NACK of ACK / NACK, the NACK information is transmitted to the Node B, but the Node B retransmits the forward information, The need to transmit is reduced.

Therefore, in the present embodiment, when one UE transmits reverse cellular information including an ACK / NACK to a base station through a cellular channel and simultaneously transmits D2D information to another D2D terminal through a D2D channel, the importance of the ACK and NACK Considering that ACK / NACK information is ACK, only the D2D channel is transmitted and only the cell channel is transmitted. When the ACK / NACK information is NACK, a method of transmitting only the D2D channel without transmitting the cellular channel is proposed.

With reference to the fourth embodiment of the present invention described above, the operation of the terminal will be described with reference to FIG.

When the UE starts operating in step 1101 of FIG. 11, it prepares for transmission of D2D information in step 1102. FIG. In step 1103, if necessary, preparation for transmission of the cellular information is performed. In this case, the information included in the PUCCH may be included in the information for preparing for transmission in step 1103.

In step 1104, the MS determines whether transmission of uplink control information (PUCCH) is required. If the PUCCH transmission is not required, the MS transmits D2D information in step 1106. [ On the other hand, if it is determined in step 1104 that the transmission of the PUCCH is required, it is determined in step 1105 whether the ACK / NACK information included in the PUCCH is ACK or NACK again.

If the ACK / NACK information is ACK, the UE proceeds to step 1107 and transmits a PUCCH. On the other hand, if the ACK / NACK information is NACK, the UE proceeds to step 1106 and transmits D2D information.

In step 1106, D2D information is transmitted, but PUCCH information is not transmitted. In step 1107, PUCCH information is transmitted but D2D information is not transmitted.

After completing steps 1106 and 1107, the operation of the terminal is terminated in step 1108. [

Example 5: Cellular  Channel Transmission D2D  Selecting simultaneous channel reception

In this embodiment, it is assumed that one mobile station transmits reverse cellular information to a base station over a cellular channel and receives D2D information from another D2D terminal through a D2D channel at the same time.

The terminal can not transmit and receive simultaneously through the same band. Therefore, in the present invention, when the UE is required to simultaneously perform the transmission of the cellular channel and the reception of the D2D channel, the following operation is possible. Preferably, one of the operations described below can be selected and performed.

1. Receive only the D2D channel.

2. Send only the cellular channel.

3. In accordance with the setting of the base station, the mobile station selects one of the D2D channel reception and the transmission of the cellular channel. (In this case, the base station transmits, To the terminal, which of the operations of transmission of the D2D channel and reception of the D2D channel should be given priority.

Example 6: Cellular  Depending on the type of control information Cellular  The transmission of control information and D2D  Choosing to receive channels

In this embodiment, it is assumed that one mobile station transmits reverse cellular information including ACK / NACK to a base station through a cellular channel and simultaneously receives D2D information from another D2D terminal through a D2D channel.

The UE transmits ACK / NACK information to the Node B, which means that the UE informs the Node B via ACK / NACK of whether information has been correctly received for the forward information received from the Node B.

When the information transmitted from the mobile station to the base station is ACK of ACK / NACK, that is, when the forward information is correctly received, the ACK information must be transmitted to the base station to prevent further retransmission. On the other hand, when the information transmitted from the mobile station to the base station is NACK of the ACK / NACK, the NACK information is not transmitted to the base station but the base station retransmits the forward information. Therefore, compared to the necessity of transmitting ACK information, Lt; RTI ID = 0.0 > a < / RTI >

Therefore, in the present embodiment, when one UE transmits reverse cellular information including an ACK / NACK to a base station through a cellular channel and simultaneously transmits D2D information to another D2D terminal through a D2D channel, the importance of the ACK and NACK If the ACK / NACK information is ACK, the D2D channel is not received and the cell channel is transmitted. If the ACK / NACK information is NACK, the D2D channel is received without transmitting the cell channel.

The operation procedure of the terminal according to the present embodiment will now be described with reference to FIG.

If the UE starts the operation in step 1201 of FIG. 12, it prepares for reception of the D2D information in step 1202 and prepares to transmit the cellular information if necessary in step 1203. The cell information in step 1203 may include information included in the PUCCH.

The UE determines in step 1204 whether transmission of the PUCCH is necessary. As a result of the determination, if the PUCCH transmission is not required, the D2D information is received in step 1206.

On the other hand, if it is determined in step 1204 that the PUCCH transmission is required, it is determined in step 1205 whether the ACK / NACK information included in the PUCCH is ACK again. If the ACK / NACK information is ACK, the UE proceeds to step 1207 and transmits a PUCCH. On the other hand, if the ACK / NACK information is NACK, the UE proceeds to step 1206 and receives D2D information.

In step 1206, D2D information is received but PUCCH information is not transmitted. In step 1207, PUCCH information is transmitted but D2D information is not received. After completing steps 1206 and 1207, the UE ends its operation in step 1208. [

According to the embodiment of the present invention described above, it is possible to prevent a situation in which the reception sensitivity degradation phenomenon occurs in the terminal performing the existing cellular communication by controlling the transmission power of the terminal performing terminal-to-terminal communication. According to another embodiment of the present invention, the operation of a terminal in a case where one terminal simultaneously performs cellular communication and terminal-to-terminal communication can be clearly defined.

The embodiments of the present invention disclosed in the present specification and drawings are intended to be illustrative only and not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

Claims (22)

A method of controlling power of a terminal for terminal-to-terminal communication in a wireless communication system,
Receiving power control related information for the terminal-to-terminal communication from the base station;
Determining a transmission power of the terminal based on the maximum available power of the terminal and the power control related information for the received terminal to terminal communication; And
And transmitting data according to the determined transmission power. The power control apparatus according to claim 1,
Information on the transmission power determined according to the reception power of the reception terminal for the terminal-to-terminal communication and information on the transmission power determined based on the reception signal when the base station receives the signal of the terminal-to-terminal communication The power control method of the terminal. 2. The method according to claim 1,
The maximum available power of the terminal, the transmission power determined according to the reception power of the reception terminal of the terminal-to-terminal communication, the transmission power determined based on the reception signal when the base station receives the signal of the terminal- And determines a smaller value as the transmission power of the terminal. 3. The method of claim 2, wherein the transmission power determined according to the reception power of the reception terminal for the terminal-
Wherein the terminal power is determined as a sum of a received power of a receiving terminal for the terminal-to-terminal communication and a path loss depending on a distance between the terminals performing the terminal-to-terminal communication. 3. The method of claim 2, wherein the transmission power determined according to the reception signal when the base station receives the terminal-
Wherein the reception signal is determined by a sum of a reception signal when the base station receives a signal of the terminal-to-terminal communication and a path offset depending on a distance between the transmission terminal performing the terminal-to-terminal communication and the base station, A method of controlling power of a terminal. A terminal for controlling power for terminal-to-terminal communication in a wireless communication system,
A transmitting and receiving unit for transmitting and receiving signals to and from a terminal or a base station; And
Determining power control related information for the terminal to terminal communication from the base station and determining a transmission power of the terminal based on the maximum available power of the terminal and power control related information for the received terminal to terminal communication, And control to transmit data according to the determined transmission power. 7. The power control apparatus according to claim 6,
Information on the transmission power determined according to the reception power of the reception terminal for the terminal-to-terminal communication and information on the transmission power determined based on the reception signal when the base station receives the signal of the terminal-to-terminal communication To the terminal. 7. The apparatus of claim 6,
The maximum available power of the terminal, the transmission power determined according to the reception power of the reception terminal of the terminal-to-terminal communication, the transmission power determined based on the reception signal when the base station receives the signal of the terminal- And determines a smaller value as the transmission power of the terminal. 8. The method according to claim 7, wherein the transmission power determined according to the reception power of the reception terminal for the terminal-
Wherein the terminal is determined as the sum of the received power of the receiving terminal for the terminal-to-terminal communication and the path loss depending on the distance between the terminals performing the terminal-to-terminal communication. 8. The method of claim 7, wherein the transmission power determined according to the reception signal when the base station receives the terminal-
Wherein the reception signal is determined by a sum of a reception signal when the base station receives a signal of the terminal-to-terminal communication and a path offset depending on a distance between the transmission terminal performing the terminal-to-terminal communication and the base station, Terminal. A method of controlling power of a terminal for terminal-to-terminal communication in a wireless communication system,
Receiving transmission-related information for the terminal-to-terminal communication from the base station;
Determining whether a transmission subframe of the cellular information to be transmitted to the base station is a subframe allowing the terminal to terminal communication based on the transmission related information;
Determining a transmission power using a first offset value included in the transmission-related information when the transmission sub-frame of the cellular information is a sub-frame permitting the UE-to-terminal communication as a result of the determination; And
And transmitting the cell information to the base station according to the determined transmission power. 12. The method according to claim 11,
Determining a transmission power using a second offset value included in the transmission-related information when the transmission sub-frame of the cellular information is not a sub-frame allowing the UE-to-terminal communication as a result of the determination Wherein the power control method comprises the steps of: 12. The method according to claim 11,
Wherein the transmission-related information is received through at least one of system information, higher layer signaling, and physical layer control information. A terminal for controlling power for terminal-to-terminal communication in a wireless communication system,
A transmitting and receiving unit for transmitting and receiving signals to and from a terminal or a base station; And
Based on the transmission-related information, whether the transmission sub-frame of the cellular information to be transmitted to the base station is a sub-frame permitting the UE-to-terminal communication, If the transmission sub-frame of the resultant cellular information is a sub-frame permitting the UE-to-terminal communication, determines a transmission power using a first offset value included in the transmission-related information, To the base station, to the base station. 15. The apparatus of claim 14,
Wherein if the transmission sub-frame of the cellular information is not a sub-frame permitting the UE-to-terminal communication as a result of the determination, the transmission power determining unit determines the transmission power using a second offset value included in the transmission- . 15. The apparatus of claim 14,
And receives the transmission related information through at least one of system information, higher layer signaling, and physical layer control information. A method of multiplexing terminals for terminal-to-terminal communication in a wireless communication system,
Determining whether transmission of uplink control information including an ACK or a NACK with respect to reception of forward information is necessary at an arbitrary point in time;
Determining whether the information included in the uplink control information is ACK or NACK when transmission is required; And
And if the information included in the uplink control information is ACK, transmitting the uplink control information to the base station without transmitting information on the UE-to-terminal communication. Way. 18. The method of claim 17,
And transmitting information on the UE-to-UE communication without transmitting the uplink control information when the information included in the uplink control information is NACK as a result of the determination. . 18. The method of claim 17,
And if the information included in the uplink control information is NACK as a result of the determination, receiving information on the terminal-to-terminal communication. A terminal for multiplexing cellular information and terminal-to-terminal communication information in a wireless communication system,
A transmitting and receiving unit for transmitting and receiving signals to and from a terminal or a base station; And
Determines whether transmission of uplink control information including an ACK or NACK with respect to reception of forward information is necessary at a certain point of time, and determines whether information included in the uplink control information is ACK or NACK when transmission is required, And controls the uplink control information to be transmitted to the base station without transmitting information on the terminal-to-terminal communication when the information included in the uplink control information is ACK. 21. The apparatus of claim 20,
Wherein the controller controls to transmit information on the terminal-to-terminal communication without transmitting the uplink control information when the information included in the uplink control information is NACK. 21. The apparatus of claim 20,
Further comprising the step of receiving information on the terminal-to-terminal communication when the information included in the uplink control information is NACK as a result of the determination.

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