KR102213461B1 - Method and apparatus for power control and multiplexing for device to device communication in wirelss cellular communication system - Google Patents

Abstract

With the development of various new services in wireless cellular communication systems, the need for terminal-to-terminal communication is increasing. When terminal-to-terminal communication is used in a cellular communication system, a terminal for conventional cellular communication and a terminal for terminal-to-terminal communication exist together, and a problem arises. When there are two different terminals that perform cellular communication and terminal-to-terminal communication at the same time, one or more different signals are received in the reception of the base station or the reception of the terminal. On the other hand, when the size is larger than a certain size, reception sensitivity decreases, which makes it difficult to receive a small signal.
The present invention provides a method for avoiding a situation in which the reception sensitivity decreases to the existing cellular communication terminal by controlling the transmission power of a terminal performing terminal-to-terminal communication. In addition, it provides a method of multiplexing the operation of a terminal, particularly information on terminal-to-terminal communication and information on cellular communication, when a single terminal must simultaneously perform cellular communication and terminal-to-terminal communication.

Description

Power control and multiplexing method and apparatus for performing terminal-to-terminal communication in a wireless cellular communication system {METHOD AND APPARATUS FOR POWER CONTROL AND MULTIPLEXING FOR DEVICE TO DEVICE COMMUNICATION IN WIRELSS CELLULAR COMMUNICATION SYSTEM}

The present invention relates to a general wireless mobile communication system, and in particular, a terminal operation including a transmission power control procedure and a multiplexing procedure of a terminal in a state in which terminal-to-terminal communication technology and wireless cellular communication technology are mixed and used, and the corresponding Base station operation, and their apparatus.

As the types of services using wireless mobile communication systems are greatly diversified, there is a need for new technologies to support newly emerging services more efficiently, and accordingly, new methods and new technologies are developed and researched within the wireless mobile communication system. Is becoming.

Device-to-device (D2D) communication is a new technology that has emerged as a solution to a new service, and terminal-to-device communication is basically a technology that allows an arbitrary terminal to communicate directly with other terminals existing around the terminal. to be. Using the terminal-to-terminal communication technology, the terminal discovers which terminals exist around the terminal, and can perform direct communication with a terminal requiring communication.

When a terminal to a terminal performs direct communication, it has a great advantage in terms of radio resource efficiency because relatively few radio resources are used compared to performing communication using a base station using an existing wireless network. In addition, since the method to find the terminal around the terminal is supported, the terminal can directly provide the necessary information to the desired terminal, greatly increasing efficiency in supporting advertising services and social networking services (SNS). You can increase it.

Currently, Long Term Evolution-Advanced (LTE-A) systems also require support for terminal-to-terminal technology, and technical discussions are underway.

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

The base station 101 manages the terminal 103 and the terminal 104 in the cell 102 controlled by the base station. The terminal 103 performs cellular communication using the base station 101 and the terminal-base station link 106, and the terminal 104 performs cellular communication using the base station 101 and the terminal-base station link 107. do. When terminal-to-terminal communication is possible between the terminal 103 and the terminal 104, it is possible to directly exchange information with each other using the terminal-to-terminal link 105 without going through the base station 101.

Terminal-to-device (Device to Device: hereinafter referred to as D2D) technology using a cellular wireless mobile communication system such as the LTE-A system is basically assumed to be executed in a direction that does not damage the terminal using the existing cellular system as much as possible. do. To this end, a radio resource used by a cellular terminal (in the present invention, a cellular terminal refers to a terminal performing conventional terminal-to-base station communication, not terminal-to-terminal communication), and resources that do not overlap each other may be used for D2D communication, and Or, although the D2D terminal uses the same resource used by the cellular terminal, it may be considered to be used so as not to interfere with each other as much as possible.

There is frequency division duplexing (hereinafter referred to as FDD) as a reverse and forward duplexing method used by an LTE or LTE-A system.

In the FDD, the forward direction and the reverse direction are distinguished by using different frequency resources. In the case of using D2D communication separately from existing cellular communication resources in a system using the FDD, in general, a method of using a reverse frequency resource as D2D among forward and reverse resources tends to be more prioritized. This is because in the FDD system, forward frequency resources are multiplexed with more types of signals than reverse frequency resources, so it is difficult to allocate resources separately for D2D communication purposes compared to reverse resources.

In addition, in the FDD system considering only the existing cellular terminals, the forward traffic tends to be more than the reverse direction due to the characteristics of the communication service, and the overhead transmitted in the forward direction is higher than that in the reverse direction. It is generally greater than the frequency usage burden for resources.

Therefore, when forward resources are allocated and used for D2D communication purposes, the burden on the forward resources increases, and it may be difficult to balance the use of forward and reverse frequency resources.

Assuming that D2D communication is performed using reverse resources in a communication system using FDD, the problem caused by using the forward resources of the D2D technology described above can be solved. However, even if the D2D communication technology is applied using reverse resources, not all problems are solved. For example, in the reverse resource used in the LTE system, resources of an arbitrary size may be allocated to both ends of the entire band in order to transmit control information for an existing cellular terminal.

The control information transmitted in the reverse direction includes forward link channel state information of the terminal (Channel Quality Information: hereinafter CQI), ACK/NACK information, which is response information for a hybrid automatic retransmission (HARQ) technology of forward communication, and Scheduling request information for transmission of reverse information may be included.

The control information is transmitted from arbitrary terminals in the reverse direction, that is, to the base station. Transmission of the control information may occur when only cellular terminals perform communication on the reverse resource as well as when D2D terminals communicate between terminals. That is, there may be a case in which a plurality of D2D terminals communicate with each other at the same time within the same cell (for example, within the same subframe in LTE), and the cellular terminal transmits control information to the base station. In the above case, it may be assumed that the frequency resource used by the cellular terminal for transmission of control information and the frequency resource used by the D2D terminal for inter-terminal communication are different from each other and the same case.

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

Base station 201 has a cell, and terminals 203, 205, and 206 are located in the cell. The terminal 203 transmits 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 may 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 an appropriate reception power when receiving the reverse control information. In addition, the terminal 205 appropriately sets the transmission power for information transmission so that the terminal 206 can have an appropriate reception power when receiving the D2D transmission.

In this case, as the distance between the terminal 205 and the terminal 206 increases, the terminal 205 may perform D2D transmission by setting a large transmission power so that transmission to the terminal 206 is properly performed. In this case, when the terminal 205 is located very close to the base station 201, the D2D transmission transmitted by the terminal 205 to the terminal 206 may be received by the base station 201 with very large reception power.

At this time, if the received power received by the base station 201 from the terminal 205 (refer to 208) is greater than a certain value compared to the signal transmitted by the cellular terminal 203 in the reverse direction, a desensitization phenomenon occurs when receiving the signal. There is a concern that a problem in which the base station 201 cannot receive the reverse control information transmitted by the 203 may occur.

In the above, when a cellular terminal included in one base station and a D2D terminal simultaneously transmit using reverse frequency resources, the information transmitted from the cellular terminal increases as the difference in strength of the received signal received from the cellular terminal and the D2D terminal by the base station increases. The problem of not receiving is described. In the present invention, a power control procedure of a D2D terminal for solving a problem caused by a lack of reception sensitivity in the above-described scenario, and an operation of the related base station and the terminal are described.

The present invention has been conceived to solve the above problems, and in a mobile communication system, a terminal using D2D technology and a cellular terminal do not cause a problem of reducing reception sensitivity between each other, and a D2D channel required for simultaneous communication An object thereof is to provide a power control procedure, a procedure for simultaneously transmitting D2D data and cellular data by a single terminal, and a method and apparatus for operating a base station and a terminal to support the above procedures.

In the wireless communication system of the present invention to achieve the above object, the power control method of a terminal for terminal-to-terminal communication includes the steps of receiving power control-related information for the terminal-to-terminal communication from a base station, the maximum of the terminal. And determining the transmission power of the terminal based on the available power and the received power control-related information for the terminal-to-terminal communication, and transmitting data according to the determined transmission power.

In addition, in the wireless communication system of the present invention, a terminal controlling power for terminal-to-terminal communication receives a transmission/reception unit for transmitting and receiving a signal with a terminal or a base station, and power control-related information for the terminal-to-terminal communication from the base station. And a control unit that determines the transmission power of the terminal based on the maximum available power of the terminal and the received power control-related information for terminal-to-terminal communication, and controls to transmit data according to the determined transmission power. It is characterized.

On the other hand, in a wireless communication system according to another embodiment of the present invention, a method for controlling power of a terminal for terminal-to-terminal communication includes the steps of receiving transmission-related information for the terminal-to-terminal communication from a base station, based on the transmission-related information. , Determining whether the transmission subframe of the cellular information to be transmitted to the base station is a subframe that allows the terminal-to-terminal communication, and as a result of the determination, when the transmission subframe of the cellular information is a subframe that allows the terminal-to-terminal communication And determining 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 controlling power for terminal-to-terminal communication includes a transceiver for transmitting and receiving a signal with a terminal or a base station, and transmission-related information for the terminal-to-terminal communication from the base station. And, based on the transmission-related information, it is determined whether the transmission subframe of the cellular information to be transmitted to the base station is a subframe allowing the terminal-to-terminal communication, and as a result of the determination, the transmission subframe of the cellular information is the terminal-to-terminal In the case of a subframe allowing communication, a control unit for determining transmission power using a first offset value included in the transmission related information, and controlling to transmit the cellular information to the base station according to the determined transmission power. It features.

In addition, in the wireless communication system according to another embodiment of the present invention, the terminal multiplexing method for terminal-to-terminal communication requires transmission of uplink control information including ACK or NACK for whether forward information is received at an arbitrary point in time. Determining whether it is necessary, determining whether the information included in the uplink control information is ACK or NACK when transmission is necessary, and when the determination result, the information included in the uplink control information is ACK, UE to UE And transmitting the uplink control information to a base station without transmitting information on communication.

In addition, in a wireless communication system according to another embodiment of the present invention, a terminal multiplexing cellular information and terminal-to-terminal communication information includes a transmission/reception unit for transmitting/receiving a signal with a terminal or a base station, and whether forward information is received at any time. It determines whether transmission of uplink control information including ACK or NACK is required, and when transmission is required, determines whether information included in the uplink control information is ACK or NACK, and as a result of the determination, information included in the uplink control information When is ACK, the uplink control information is transmitted to the base station without transmitting information on terminal-to-terminal communication.

According to an embodiment of the present invention, by controlling the transmission power of a terminal performing terminal-to-terminal communication, it is possible to prevent a situation in which a reception sensitivity reduction phenomenon occurs in a terminal performing the existing cellular communication as much as possible. According to another embodiment of the present invention, it is possible to clearly define the operation of a terminal when one terminal simultaneously performs cellular communication and terminal-to-terminal communication.

1 is a basic diagram of terminal-to-terminal communication.
2 is a reverse frequency resource used as a terminal to terminal resource
3 is a flow chart illustrating an autonomous cell deactivation process according to an embodiment of the present invention.
4 is a flowchart illustrating an operation sequence of a small cell 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 apparatus of a D2D terminal according to an embodiment of the present invention.
6 is a block diagram showing an internal structure of a base station apparatus for power control of a D2D terminal according to an embodiment of the present invention.
7 is a flow chart showing an operation sequence of a terminal according to an embodiment of the present invention.
8 is a flow chart showing an operation sequence of a base station according to an embodiment of the present invention. 9 is a block diagram showing 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 flow chart showing a multiplexing operation sequence of a terminal according to an embodiment of the present invention.
12 is a flow chart showing a multiplexing operation sequence of a terminal according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail together with the accompanying drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary depending on the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout this specification.

In addition, in describing the embodiments of the present invention in detail, the OFDM-based wireless communication system, in particular, the 3GPP EUTRA standard will be the main target, but the main subject of the present invention is other communication systems having a similar technical background and channel type. In addition, it can be applied with slight modifications within the range not significantly departing from the scope of the present invention, which will be possible by judgment of a person skilled in the technical field of the present invention.

In the embodiments of the present invention described below, a base station or cell may be used with the same meaning. In addition, D2D communication may be used to include both a terminal discovery operation for finding a neighboring terminal and direct communication in which the terminal and the terminal directly exchange information.

In the above, when an FDD system is assumed as the duplexing method to which the present invention is applied, it has been described that D2D communication is supported using reverse frequency resources.

FIG. 3 is a diagram illustrating resources that can be used in D2D by dividing them using a format of reverse resources currently supported by LTE.

In FIG. 3, reference numeral 301 shows that a plurality of subframes are gathered along the time axis. The subframe is a time unit used in LTE, which means a 10ms time interval including a plurality of symbols.In the present invention, a subframe used in LTE is exemplified, but is not limited thereto and can be applied to an arbitrary time unit. have.

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

Looking at the resource of D2D subframes 303 in detail, several subframes may be included in the reverse resource for D2D. 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 several subcarriers on a frequency axis.

And as described above, in the LTE reverse resource, among the subcarriers available on the frequency axis, as shown in 304 and 305 of FIG. 3, a plurality of subcarriers located at both ends are reverse control information (in LTE, Physical Uplink It is used for transmission of Control Channel (means PUCCH). As described in the prior art, the reverse control information includes forward link channel state information of the terminal (Channel Quality Information: hereinafter CQI), ACK/ which is response information for hybrid automatic retransmission (Hybrid Automatic ReQuest: hereinafter HARQ) technology of the terminal. NACK information and scheduling request information for transmission of reverse information may be included.

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 may be used for transmission of a sounding reference signal (SRS) required for channel estimation of the UEs in the reverse direction in the base station. Since the transmission period of the SRS varies according to the configuration of the base station, a subframe including the SRS may exist, and a subframe including the SRS may also exist. In a subframe without SRS, the last symbol 307 can be used as a resource for D2D, and due to the nature of D2D, there is a case that the UE must continuously transmit and receive.At this time, while changing the operation from transmission to reception, or The last symbol 307 may be used as a transition time required while changing the operation to transmission.

The lack of reception sensitivity (desensing) based on the reverse resource shown in FIG. 3 can be described with reference to FIG. 2, that is, a terminal 205 located close to an arbitrary base station 201 uses a D2D communication channel 207. Therefore, when the other cellular terminal 203 transmits the PUCCH 204 to the base station 201 in a situation in which a remote terminal 206 is transmitted using D2D resources, the base station 201 is transmitted by the terminal 203 due to a decrease in reception sensitivity. There occurs a situation in which the PUCCH 204 cannot be accurately 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 reaches the base station 201, a situation in which the reception strength is very large may occur. The present invention proposes a method for solving the above situation in which a base station cannot receive information of a cellular terminal due to communication of a D2D terminal through the following embodiments.

First, before describing the transmission power control proposed in the present invention, a transmission power control method in a case where a transmitter and a receiver communicate in general, particularly when the transmitter is a terminal will be described. The transmission power used when the terminal transmits an arbitrary channel to the base station may be determined as a small value among the following two variables.

1. The maximum available power of the transmitter (terminal)

2. When the receiver (base station) receives the signal transmitted by the transmitter (terminal), the transmission power that can match the desired reception power

Here, the maximum available power of the transmitter, that is, of the terminal may be the power that the transmitter can physically use limited by the hardware of the terminal for information transmission, or the maximum power determined by an arbitrary setting of the base station. I can. The receiver, that is, the base station, makes an effort to adjust the reception power of the terminal to a predetermined value. This is to prevent a decrease in reception sensitivity when signals from multiple terminals are simultaneously received, and to facilitate scheduling of transmissions of the terminal. will be. Therefore, the terminal limits the transmission power in order to match the reception power of the base station.

Accordingly, the transmission power of the terminal can be determined by the above two variables, and the transmission power of the terminal 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 terminal, Max_Tx_Power is the maximum available power of the terminal, Rx_Power is the received power of the base station receiving the transmission signal of the terminal, and the function f (Rx_Power) is the terminal when the Rx_Power is determined. It is the transmit power determined accordingly. The function f(Rx_Power) can be variously determined using the value of Rx_Power, and the most representative equation is as follows.

f(Rx_Power) = Rx_Power + Prop_loss

In the above, Prop_loss is a path loss according to the distance between the transmitter and the receiver, and is determined not only by the distance between the transceivers, but also by the state in which the transceiver is located, and a medium that exists between the transceivers. When the terminal measures the reception power of the reference signal transmitted by the base station and measures the transmission power of the reference signal from the base station, it is possible to know the path loss value of the terminal and the base station. The path loss value is a value measured over a long term, and since it can be assumed that the path loss in the reverse direction and the forward direction is the same, the path loss value measured in the forward direction can be used for power control of the reverse transmission. .

The f(Rx_Power) equation can be defined using various variables in addition to the path loss value. The variables may be the amount of resources of the channel to be transmitted (eg, the number of physical resource blocks (PRBs) defined in LTE), an arbitrary offset value set by the base station, and various other variables. The f(Rx_Power) equation may take a method of adding a random weight to each variable and adding it. The weight can be changed, the base station can set it, and can correspond to a positive or negative value.

Hereinafter, a method of solving the phenomenon of lowering the reception sensitivity of a base station through power control of a D2D terminal will be described through various embodiments.

Example 1: D2D Channel power control

In this embodiment, a terminal performing D2D communication is a D2D link (in the present invention, a link refers to a radio path through which information is transmitted between a transmitter and a receiver, and may be used in the same sense as a radio link, channel, radio channel, access, etc. In the case of transmitting a signal through .), a method of supporting both information transmission through the D2D link and resolution of the reception sensitivity reduction of the base station is proposed through appropriate 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 a D2D terminal existing in the base station at the same time or in the same subframe uses a D2D channel. In a transmitting situation, the transmission power of the D2D terminal may be determined as any one of the following three variables, and may be determined as the smallest value among the three variables according to a preferred embodiment of the present invention.

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 by the transmitting D2D terminal (205 in Fig. 2), the transmission power that can set the desired reception power

3. When the base station (201 in Fig. 2) receives the signal transmitted by the transmitting D2D terminal (205 in Fig. 2), the base station decreases the reception sensitivity in receiving signals from other cellular terminals (203 in Fig. 2). Transmit power enough to not cause a phenomenon

The maximum available power of the terminal may be the power that the transmitter can physically use limited by the hardware of the terminal for information transmission, or may be the maximum power determined by an arbitrary setting of the base station. In addition, the reason for making an effort to match the D2D channel transmitted by the transmitting D2D terminal to the receiving D2D terminal with appropriate reception power is to facilitate the scheduling of the transmission of the transmitting D2D terminal. The third variable is, assuming that the base station receives the D2D transmission transmitted by the transmitting D2D terminal, the reception power of the D2D transmission is maintained below a certain level and is not larger than a signal received from other cellular terminals by a certain value or more. It is a value that is not enough. In this case, the third variable is to prevent a situation in which the reception signal of the D2D terminal in the base station is too large than the reception signal of the cellular terminal to reduce the reception sensitivity of the signal of the living cellular terminal. When the above contents are shown by the equation, it is as follows.

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

In the above 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, Rx_Power_D2D is the reception power of the receiving D2D terminal receiving the transmission signal of the transmitting D2D terminal, and Rx_Power_2NB is the transmission power of the transmitting D2D terminal. It may be the received power when the base station receives the transmission signal.

And 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) may be determined in various ways using the value of Rx_Power_D2D, and 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 not only by the distance between the transceivers, but also by the state in which the transceiver is located, and a medium that exists between the transceivers. When the transmitting D2D terminal and the receiving D2D terminal establish a D2D channel, the transmitting D2D terminal may know the path loss through transmission and reception of an arbitrary promised signal and sharing information about the transmission power of the promised signal.

The f(Rx_Power_D2D) equation may be defined using various variables in addition to the path loss value. The above variables are the amount of resources of the channel to be transmitted (for example, the number of PRBs (Physical Resource Blocks) defined in LTE), or an arbitrary offset value set by the base station or through channel setting between D2D terminals, and other various For example, there are several variables. The f(Rx_Power_D2D) equation may take a method of adding and adding a random weight to each variable. The weight may be changed, may be set by the base station or may be set through channel setup between D2D terminals, and may correspond to a positive value or a negative value.

The function g(Rx_Power_eNB) can be defined in various ways using the value of Rx_Power_eNB, and the most representative equation is as follows.

g(Rx_Power_eNB) = Rx_Power_eNB + Prop_loss_eNB + Desense_Offset

In the above, Prop_loss_eNB is a path loss according to the distance between the transmitting D2D terminal and the base station, and is determined by the distance between the transmitting D2D terminal and the base station, as well as the state in which the transmitting D2D terminal and the base station are located, and the medium that exists between the transmitting D2D terminal and the base station. In addition, the transmitting D2D terminal measures the reception power of the reference signal transmitted by the base station, and the transmission power of the reference signal from the base station is measured 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 adjusted so as not to decrease reception sensitivity when the base station receives the D2D signal and a signal from another cellular terminal together. The desense offset (Desense_Offset) may be determined as an arbitrary value in consideration of the performance of a receiver of the base station, and may be set by the base station and notified to the transmitting D2D terminal.

The g(Rx_Power_eNB) equation can be defined using various variables in addition to the path loss value. The variables may include the amount of resources of the D2D channel to be transmitted (for example, the number of physical resource blocks (PRBs) defined in LTE), an arbitrary offset value set by the base station, and various other variables. The g(Rx_Power_eNB) equation may take a method of adding random weights to each variable and adding them. The weight can be changed, can be set by the base station, and can correspond to 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 is shown.

4 is a flowchart illustrating a process of controlling transmission power of a 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 establish D2D (or a channel for D2D communication) in step 404. In step 404, the information of the base station may be used. For example, in order for D2D transmission/reception terminals to discover each other, perform data scheduling, and actually transmit data, synchronization must be performed, and the synchronization is performed using synchronization signals (PSS, SSS) transmitted by the base station, etc. Can be done.

Subsequently, the transmitting D2D terminal 401 receives 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) in the above equation, or information used when determining g(Rx_Power_eNB). The receiving D2D terminal of 402 may also receive 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 in step 406 is not necessarily the same as the power control related information in step 405.

In FIG. 4, the base station giving power control-related information to the transmitting D2D terminal 401 and the base station providing power control-related information to the receiving D2D terminal 402 are the same base station 403, but are not limited thereto, for example, each D2D terminal If the base station to which the base station belongs is different base stations, they may be different base stations.

Subsequently, the transmitting D2D terminal 401 and the receiving D2D terminal 402 may determine a path loss for the D2D channel. The determination of the path loss may be determined in advance 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 the reference signal transmission in step 407 and the path loss calculation and measurement report according to the measurement of the reference signal in step 408. The transmitting D2D terminal 401 has information and the following equation

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

D2D channel transmission may be performed in step 409 by using.

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

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

Power control-related information stored in the storage unit 501 is input to the power control controller 502, and the power control controller 502 determines the transmission power of the D2D channel using the above equation, and transmits the D2D channel to the power amplifier through a control signal 503. Enter the transmit power.

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

In the above, the power controller 502 and the D2D channel generator 504 are divided into separate blocks. However, they do not necessarily need to be divided into physically divided hardware as described above, and may be implemented as detailed functional blocks performed by the controller.

6 is a block diagram showing 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 determining unit 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 setting value may include information used when determining f(Rx_Power_D2D). In addition, the D2D power control-related setting value determining unit of the base station determines a power control-related setting value required when the base station receives a D2D channel (602). The power control-related setting 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 signaled procedure has been shown in step 405 of FIG. 4. In FIG. 6, the D2D power control-related setting value determination unit is divided into two blocks, but it is not necessary to be divided into physically separated hardware as described above, and may be implemented as detailed function blocks performed by the control unit. Be careful.

Example 2: D2D If the 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 the problem of deterioration of reception sensitivity of a cellular terminal due to D2D link reception of a D2D terminal in a location adjacent to the base station.

In the above, when a cellular terminal transmits information using a cellular channel in the reverse direction, it has been described that 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 terminal, Max_Tx_Power is the maximum available power of the terminal, Rx_Power is the received power of the base station receiving the transmission signal of the terminal, and the function f (Rx_Power) is the terminal when the Rx_Power is determined. It is the transmit power determined accordingly.

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

That is, in order to prevent the problem of deterioration of reception sensitivity due to the D2D terminal when the base station receives the transmission of the cellular terminal due to the presence of a D2D terminal near the base station, the cellular terminal is added to the transmit power when there is a D2D terminal. It includes a method of transmitting a stronger transmission signal by adding an offset. This 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 terminal, Max_Tx_Power is the maximum available power of the terminal, Rx_Power is the received power of the base station receiving the transmission signal of the terminal, and the function f (Rx_Power) is the terminal when the Rx_Power is determined. It may be a transmission power determined accordingly. Finally, the variable offset_D2D is an offset having a different value according to the presence or absence of a D2D terminal performing simultaneous transmission with the cellular terminal when a cellular terminal transmits arbitrary data information or control information.

In general, it is possible to set a larger offset_D2D value when there is a D2D terminal transmitting at the same time compared to a case where it is not. For example, when a D2D terminal exists, offset_D2D (first offset) = 5dB, when a D2D terminal does not exist, offset_D2D (second offset) = 0dB, etc. can be used.

In addition, the effect of offset_D2D can be obtained by setting the variable existing in f(Rx_Power) differently. The f(Rx_Power) equation 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

Variables such as, etc. are variables set for PUCCH performance in the upper layer. One or more of these variables are divided into two sets, one set used in a general subframe for which D2D is not set, and D2D Another set used in the configured subframe is set. The UE may determine whether or not D2D exists in the subframe currently transmitting the PUCCH, select one of two set variables or set of variables, and substitute it into the above equation to use for setting the PUCCH power.

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

Meanwhile, in the above equation, the function f(Rx_Power) may be determined by the method described above.

Meanwhile, in order for the cellular terminal to know whether or not the D2D terminal is simultaneously transmitted, the base station may inform all terminals belonging to the base station of the subframe in which the D2D channel exists using system information. In addition, the base station may inform each terminal of the transmission time of the D2D terminal, and in this case, the base station may inform the terminal through higher layer signaling or physical layer control information.

In the following, an operation sequence of the terminal and the base station according to the second embodiment of the present invention will be described. 7 is a flow chart showing an operation sequence of a terminal according to a 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 and through which subframe D2D transmission is performed, and offset_D2D information according to D2D transmission in step 702.

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

In addition, with respect to the offset_D2D information according to D2D transmission, assuming that offset_D2D = A when a D2D terminal exists, and offset_D2D = B when a D2D terminal does not exist, the values for (A,B) are in the terminal. Can be set.

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

The offset_D2D information can be known through system information. Alternatively, the base station may inform the 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 it 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 by using a field reserved in an arbitrary format among conventionally defined DCI formats. In addition, the offset_D2D value may be transmitted to the terminal by defining different interpretations of arbitrary fields of the conventionally defined DCI format.

Next, the cellular terminal prepares cellular information, that is, information to be transmitted to the base station in step 703, and then, in step 704, determines whether D2D transmission is performed together at the time to transmit the cellular information by using the D2D transmission-related information acquired in step 702. . For example, the terminal may determine whether the subframe for transmitting the cellular information is a subframe allowing D2D transmission.

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

Then, the terminal offset_D2D value set in step 707 and the following equation

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

The transmit power is determined using.

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

8 is a flow chart showing an operation sequence of a base station according to the second embodiment of the present invention.

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

The terminal can obtain the D2D transmission related information from system information through a broadcast channel, and the base station can inform each terminal. Likewise, the terminal can know the offset_D2D from system information, or the base station can set and inform each terminal. In another embodiment, by defining a new DCI format including the D2D transmission related information and offset_D2D information, the base station may transmit it to the terminal through the PDCCH. Or, without defining a new DCI format, the information may be transmitted to the terminal by using a field reserved in an arbitrary format among the previously defined DCI formats, and the interpretation is defined to be different for any field of the conventionally defined DCI format. Thus, the offset_D2D value may be transmitted to the terminal.

In step 804, the operation is finished.

9 is a block diagram showing the 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 D2D transmission exists. The power control related setting value storage 902 stores the power control related setting value received from the base station. When the determination information of the D2D transmission determination unit 901 and information stored by the power control-related setting value storage 902 are input to the cellular transmission power controller 903, the transmission power for the cellular information transmitted by the MS is determined.

The offset_D2D value is stored in the power control-related setting value storage 902, and the cellular transmission power controller 903 determines the correct offset_D2D according to the determination of the D2D transmission determination unit 901. The channel to be transmitted by the present terminal is generated by the cellular channel generator 905 and amplified through the power amplifier 906, and the amplified value is determined by being input 904 to the power amplifier 906 with a value determined by the cellular transmission power controller 903. The amplified cellular information is transmitted through the transmission unit 907.

Each block shown in FIG. 9 does not necessarily need to be divided into physically divided hardware, and may be implemented as detailed functional blocks performed by the controller.

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

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 transmitter 1003.

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

A problem in the situation in which a cellular terminal transmits cellular information to a base station in the reverse direction and a D2D terminal transmits it to another D2D terminal using the same reverse frequency resource, and a solution through power control of a D2D terminal or a cellular terminal have been described. .

In the following, it is assumed that one terminal transmits or receives D2D information and transmits cellular information at the same time. The terminal may perform general cellular transmission in which reverse data information is transmitted in the reverse direction (ie, to the base station) according to the scheduling of the base station or control information according to the forward data information is transmitted in the reverse direction. However, there may be a case in which transmission or reception of D2D information for D2D is required simultaneously with the cellular transmission.

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

Another embodiment of the present invention described below is intended to propose a solution when the above-described transmission of cellular information and transmission and reception of D2D information occur simultaneously.

Example 3: Cellular Channel and D2D Transmit channels simultaneously

In the present embodiment, it is assumed that one terminal transmits reverse cellular information to a base station through 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 the number of channels simultaneously transmitted by one terminal is limited to one. When the terminal needs to simultaneously transmit the cellular channel and the D2D channel, the following operations are possible. Preferably, it can be performed by selecting any one of the operations described below.

1. Only D2D channel is transmitted.

2. Transmit only cellular channels.

3. Depending on the settings of the base station, the base station selects and transmits one of the D2D channel and the cellular channel. (In this case, the base station uses system information, higher layer signaling such as RRC signaling, or physical layer control information, When simultaneous transmission and reception of channels occurs, information on which channel to give priority to can be delivered to the terminal.)

4. Ignore the SC-FDMA method and transmit both channels simultaneously. At this time, 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 Channel selective transmission

In this embodiment, it is assumed that one terminal 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.

When the terminal transmits the ACK/NACK information to the base station, it means that the terminal informs the base station of whether or not the forward direction information already received is properly received through ACK/NACK.

When the information to be transmitted by the terminal to the base station is ACK among ACK/NACK, that is, when the forward direction information is correctly received, the ACK information must be transmitted to the base station to prevent further retransmission. On the other hand, if the information to be transmitted by the UE to the base station is NACK among ACK/NACK, the base station performs retransmission of forward information even when the NACK information is not transmitted to the base station. The need to transmit is low.

Therefore, in this embodiment, when one terminal 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 importance of the ACK and NACK Considering this, when the ACK/NACK information is ACK, only the cellular channel is transmitted without transmitting the D2D channel, and when the ACK/NACK information is NACK, the cellular channel is not transmitted and only the D2D channel is transmitted.

With respect to the fourth embodiment of the present invention described above, the operation of the terminal will be described with reference to FIG. 11 below.

When the operation of the terminal is started in step 1101 of FIG. 11, preparation for transmission of D2D information is performed in step 1102. In step 1103, if necessary, cellular information is prepared for transmission. In this case, information included in the PUCCH may be included as information prepared for transmission in step 1103.

Subsequently, the UE determines whether transmission of uplink control information (PUCCH) is required in step 1104, and if PUCCH transmission is not required, transmits D2D information in step 1106. On the other hand, if it is determined in step 1104 that 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.

In this case, if the ACK/NACK information is ACK, the UE proceeds to step 1107 to transmit a PUCCH. On the other hand, when the ACK/NACK information is NACK, the UE proceeds to step 1106 to transmit D2D information.

Step 1106 transmits D2D information but does not transmit PUCCH information. Step 1107 transmits PUCCH information but does not transmit D2D information.

When steps 1106 and 1107 are completed, the operation of the terminal is terminated in step 1108.

Example 5: Cellular Channel transmission and D2D Selection of simultaneous channel reception

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

The terminal cannot transmit and receive simultaneously through the same band. Accordingly, in the present invention, when the UE needs to simultaneously transmit the cellular channel and receive the D2D channel, the following operations are possible. Preferably, it can be performed by selecting any one of the operations described below.

1. Only D2D channel is received.

2. Transmit only cellular channels.

3. Depending on the settings of the base station, the base station selects either the reception of the D2D channel or the transmission of the cellular channel. (In this case, the base station selects the cellular channel through system information, higher layer signaling such as RRC signaling, or control information of the physical layer. It is possible to transmit information on which operation priority is given to the terminal between the transmission of the D2D channel and the reception of the D2D channel.)

Example 6: Cellular Depending on the type of control information Cellular Transmission of control information and D2D Choice of receiving channels

In the present embodiment, it is assumed that one terminal 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.

When the terminal transmits ACK/NACK information to the base station, it means that the terminal informs the base station of information on whether or not the forward direction information received from the base station has been properly received through ACK/NACK.

When the information transmitted from the terminal to the base station is ACK among ACK/NACK, that is, when the forward direction information is correctly received, ACK information must be transmitted to the base station to prevent further retransmission. On the other hand, when the information transmitted from the terminal to the base station is NACK among ACK/NACK, the base station performs retransmission of forward information even when the NACK information is not transmitted to the base station, compared to the need to transmit ACK information. The necessity to transmit the data drops.

Therefore, in this embodiment, when one terminal 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 importance of the ACK and NACK Considering that, when the ACK/NACK information is ACK, the cellular channel is transmitted without receiving the D2D channel, and when the ACK/NACK information is NACK, the cellular channel is not transmitted and the D2D channel is received.

12 illustrates a sequence of operations of the terminal according to the present embodiment.

When the operation of the terminal starts in step 1201 of FIG. 12, preparation for reception of D2D information is performed in step 1202, and transmission of cellular information is prepared if necessary in step 1203. The cellular information in step 1203 may include information included in the PUCCH.

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

On the other hand, if it is determined in step 1204 that transmission of the PUCCH is required, it is determined in step 1205 whether the ACK/NACK information included in the PUCCH is ACK. At this time, if the ACK/NACK information is ACK, the UE proceeds to step 1207 to transmit a PUCCH. On the other hand, when the ACK/NACK information is NACK, the UE proceeds to step 1206 to receive D2D information.

Step 1206 receives D2D information but does not transmit PUCCH information, and step 1207 transmits PUCCH information but does not receive D2D information. After completing step 1206 or step 1207, the operation of the terminal is terminated in step 1208.

According to the above-described embodiment of the present invention, by controlling the transmission power of a terminal performing terminal-to-terminal communication, it is possible to prevent a situation in which a reception sensitivity reduction phenomenon occurs in a terminal performing a conventional cellular communication as much as possible. According to another embodiment of the present invention, it is possible to clearly define the operation of a terminal when one terminal simultaneously performs cellular communication and terminal-to-terminal communication.

The embodiments of the present invention disclosed in the present specification and drawings are only provided for specific examples to easily explain the technical content of the present invention and to aid understanding of the present invention, and are not intended to limit the scope of the present invention. In addition to the embodiments disclosed herein, it is obvious to those of ordinary skill in the art that other modified examples based on the technical idea of the present invention may be implemented.

Claims (22)

In the method performed by the first terminal of a wireless communication system,
Receiving, from a base station, power control-related information for D2D (Device to Device) communication;
Determining a first transmission power based on the maximum available power of the terminal;
Determining a second transmit power based on the power control related information; And
And transmitting, to a second terminal, D2D signaling according to a smaller transmission power among the first transmission power and the second transmission power. The method of claim 1,
The D2D communication, characterized in that it comprises at least one of a discovery operation (operation), control information transmission, and data transmission. The method of claim 1,
The second transmission power is characterized in that it is determined based on the number of allocated resource blocks, path loss, and the power control related information. The method of claim 3,
The path loss, characterized in that it is determined for the serving cell based on information provided by signaling from the base station. In the first terminal of the wireless communication system,
A transceiver configured to transmit and receive signals; And
It includes a control unit connected to the transmission and reception unit,
The control unit:
Receives information related to power control for D2D (Device to Device) communication from the base station,
Determining a first transmission power based on the maximum available power of the terminal,
Determining a second transmission power based on the power control-related information,
The first terminal, characterized in that the second terminal is configured to transmit D2D signaling according to a smaller transmission power of the first transmission power and the second transmission power. The method of claim 5,
The D2D communication, characterized in that it comprises at least one of a discovery operation (operation), control information transmission, and data transmission, the first terminal. The method of claim 5,
The second transmission power, characterized in that it is determined based on the number of allocated resource blocks, path loss, and the power control-related information. The method of claim 7,
The first terminal, characterized in that the path loss is determined for a serving cell based on information provided by signaling from the base station. In the method performed by the first terminal of a wireless communication system,
Determining whether uplink transmission and sidelink transmission are set within a transmission time interval (TTI);
If uplink transmission is not configured within the TTI, transmitting the sidelink transmission to a second terminal based on transmission power within the TTI; And
When the uplink transmission and the sidelink transmission are set within the TTI, transmitting the uplink transmission within the TTI to a base station,
When the uplink transmission and the sidelink transmission are set within the TTI, the sidelink transmission is not transmitted to the second terminal. The method of claim 9,
The sidelink transmission, characterized in that it comprises transmission of at least one of a discovery signal, control information, and data transmission. The method of claim 9,
The method, characterized in that the transmission power is a smaller value of the first transmission power and the second transmission power. The method of claim 11,
The method further comprises receiving power control related information from the base station,
The first transmission power is determined based on the number of allocated resource blocks, path loss, and power control related information,
The second transmission power, characterized in that the maximum available transmission power for the sidelink transmission. The method of claim 12,
The path loss, characterized in that it is determined for the serving cell based on information provided by signaling from the base station. In the first terminal of the wireless communication system,
A transceiver configured to transmit and receive signals; And
It includes a control unit connected to the transmission and reception unit,
The control unit:
Determine whether uplink transmission and sidelink transmission are set within a transmission time interval (TTI),
If uplink transmission is not configured within the TTI, the second terminal transmits the sidelink transmission based on transmission power within the TTI,
When the uplink transmission and the sidelink transmission are set within the TTI, the base station is configured to transmit the uplink transmission within the TTI,
When the uplink transmission and the sidelink transmission are set within the TTI, the sidelink transmission is not transmitted to the second terminal. The method of claim 14,
The sidelink transmission, characterized in that it comprises at least one transmission of a discovery signal, control information, and data transmission, the first terminal. The method of claim 14,
The first terminal, characterized in that the transmission power is a small value of the first transmission power and the second transmission power. The method of claim 16,
The control unit is further configured to receive power control related information from the base station,
The first transmission power is determined based on the number of allocated resource blocks, path loss, and power control related information,
The second transmission power, characterized in that the maximum available transmission power for the sidelink transmission, the first terminal. The method of claim 17,
The first terminal, characterized in that the path loss is determined for a serving cell based on information provided by signaling from the base station. delete delete delete delete

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