JP6843901B2 - Power control and multiplexing methods and devices for performing D2D communication in wireless cellular communication systems - Google Patents

Description

The present invention relates to a general wireless mobile communication system, in particular, a terminal operation including a transmission power control procedure and a multiplexing procedure of a terminal in a state where D2D communication technology and wireless cellular communication technology are mixed and used, and a base corresponding thereto. Regarding station operation and these devices.

As the types of services using wireless mobile communication systems become large and diverse, there is a need for new technologies to support new services more efficiently, which is a new method within wireless mobile communication systems. And the technology has been developed and studied.

Terminal-to-terminal (D2D) communication is a new technology that has emerged as a solution to new services, and D2D communication is basically direct communication with other terminals in which any terminal exists around the terminal. It is a technology that enables you to do this. By using D2D communication technology, a terminal can discover what kind of terminals exist around it (discovery), and can perform direct communication with a terminal that requires communication (Direct communication).

If D2D communicates directly, it will use relatively less wireless resources than communication using a base station using an existing wireless network, which is large in terms of wireless resource efficiency. It will have merit. In addition, since the method of discovering terminals around the terminal is supported, it becomes possible to give necessary information directly to the terminal desired by the terminal, and advertising service, social network service (Social Networking Service: The following) It will be possible to greatly improve efficiency in supporting SNS) and the like.

Currently, even higher long-term evolution (Long Term Evolution-Advanced, hereinafter referred to as LTE-A) systems also require support for D2D technology, and technical discussions on it are underway.

FIG. 1 is a drawing showing a scenario in which D2D communication is supported in a cellular system.

The base station 101 controls the terminal 103 and the terminal 104 in the cell 102 under the control of 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 further uses the link 107 between the base station 101 and the terminal-base station for cellular communication. Come to communicate. When D2 communication is possible between the terminal 103 and the terminal 104, it is possible to directly exchange information with each other using the D2D link 105 without passing through the base station 101.

Terminal-to-terminal (Device to Device, hereinafter referred to as D2D) technology using a cellular wireless mobile communication system such as the LTE-A system basically does not cause maximum damage to terminals using an existing cellular system. Suppose it runs in the direction. For this purpose, resources that do not overlap with each other are used for D2D communication in addition to the radio resources used by the cellular terminal (in the present invention, the cellular terminal refers to a terminal that performs existing terminal-to-base station communication instead of D2D communication). Alternatively, it can be considered that the resources used by the cellular terminal are used by the D2D terminal as well, but not to interfere with each other to the maximum extent possible.

Frequency division duplexing (hereinafter referred to as FDD) is a reverse and forward duplexing method used by LTE or LTE-A systems.

In the FDD, the forward direction and the reverse direction are distinguished by using other frequency resources. When D2D communication is used separately from existing cellular communication resources in the system using FDD, the method of using the reverse frequency resource as D2D among the forward and reverse resources tends to be given higher priority. is there. This is because in the FDD system, more types of signals are multiplexed in the forward frequency resource than in the reverse frequency resource, and it is more difficult to allocate the resource separately for the D2D communication application than in the reverse frequency resource.

Further, in an FDD system that considers only existing cellular terminals, the forward traffic tends to be larger than that in 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. Because of the large number, the overhead burden of frequency usage on forward resources is generally greater than the burden of frequency usage on reverse resources.

Therefore, if the forward resources are allocated to the D2D communication use and used, the burden on the forward resources becomes larger, and it becomes difficult to balance the use of the forward and reverse frequency resources.

Assuming that D2D communication is performed using reverse resources in a communication system using FDD, the problems caused by using forward resources in the above-mentioned D2D technology can be solved. However, applying D2D communication technology using reverse resources does not solve all the problems. As an example, the reverse resource used in the LTE system can be allocated a resource of arbitrary size at both ends of the entire band for transmitting control information for an existing cellular terminal.

The control information transmitted in the reverse direction includes the forward link channel state information (CQI) of the terminal, and the hybrid automatic request (hereinafter, HARQ) technology for forward communication. ACK / NACK information which is response information, scheduling request information for transmitting information in the reverse direction, and the like can be included.

The control information will be transmitted from any terminal in the opposite direction, that is, to the base station. The transmission of the control information can occur not only when only the cellular terminal communicates with the resource in the reverse direction, but also when the D2D terminal communicates between the terminals. That is, a plurality of D2D terminals may communicate with each other at the same time in the same cell (for example, within the same subframe in LTE), and the cellular terminal may transmit control information to the base station. it can. In the above case, it is possible to assume the same case where the frequency resource used by the cellular terminal for transmitting control information and the frequency resource used by the D2D terminal for communication between the terminals are different from each other.

FIG. 2 is a drawing showing a scenario in which a cellular terminal and a D2D terminal in the same cell simultaneously send and receive signals to and from a base station using reverse resources in the same subframe.

The base station 201 has a cell, and terminals 203, 205, and 206 are located in the cell. The terminal 203 uses the reverse resource 204 to transmit reverse control information at the cellular terminal. The terminal 205 is performing D2D communication with the terminal 206, and the terminal 205 can transmit information at 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 has an appropriate reception power when receiving the reverse direction control information. Further, the terminal 205 appropriately sets the transmission power for information transmission so that the terminal 260 has an appropriate reception power when receiving the D2D transmission.

In this case, as the distance between the terminal 205 and the terminal 206 becomes longer, the terminal 205 may perform D2D transmission by setting a large transmission power so that the transmission to the terminal 206 becomes proper. At this time, when the terminal 205 is located so as to be in close contact with the base station 201, the D2D transmission transmitted by the terminal 205 to the terminal 206 can be received by the base station 201 with a very large reception power.
At this time, if the received power received by the base station 201 from the terminal 205 (see 208) is larger than a certain value or more than the signal transmitted by the cellular terminal 203 in the reverse direction, the reception sensitivity is insufficient in receiving the signal (see 208). There is a possibility that a problem may occur in which the base station 201 may not be able to receive the reverse control information transmitted by the terminal 203 due to the occurrence of the desensing phenomenon.

International Publication No. 2012/166969 Special table 2010-5004048 U.S. Patent Application Publication No. 2012/0269072

When the cellular terminal and the D2D terminal included in one base station simultaneously transmit using the reverse frequency resource, the difference in the strength of the received signals received by the base station from the cellular terminal and the D2D terminal becomes large, so that the cellular terminal becomes cellular. Described the problem of not being able to receive the information sent from the terminal. The present invention attempts to describe the power control procedure of a D2D terminal and the related base station and terminal operations for solving the problem caused by the reception sensitivity shortage phenomenon in the above-mentioned scenario.

The present invention has been devised to solve the above-mentioned problems, and according to one aspect of the present invention, there is a problem of a decrease in reception sensitivity between a terminal using D2D technology in a mobile communication system and a cellular terminal. D2D channel power control procedure required for simultaneous communication without generating D2D data, procedure for one terminal to transmit D2D data and cellular data at the same time, and operation method of base station and terminal to support the procedure. And the equipment provided.

According to one aspect of the present invention, in the wireless communication system, the power control method of the terminal for D2D communication includes the stage of receiving the power control related information for D2D communication from the base station and the maximum of the terminal. Including a step of determining the transmission power of the terminal based on the available power and the power control related information for the received D2D communication, and a step of transmitting data by the determined transmission power. It is a feature.

According to another aspect of the present invention, in the wireless communication system of the present invention, the terminal that controls power for D2D communication includes a transmission / reception unit that transmits / receives a signal to and from the terminal or a base station, and the D2D from the base station. The power control related information for communication is received, the transmission power of the terminal is determined based on the maximum usable power of the terminal and the received power control related information for D2D communication, and the determined transmission power is determined. It is characterized by including a control unit that controls to transmit data by.

According to another aspect of the present invention, in the wireless communication system, the power control method of the terminal for D2D communication is based on the stage of receiving the transmission-related information for the D2D communication from the base station and the transmission-related information. A step of determining whether the transmission subframe of the cellular information to be transmitted to the base station is a subframe that allows the D2D communication, and a case where the determination result shows that the transmission subframe of the cellular information is a subframe that allows the D2D communication. , A step of determining a transmission power using the first offset value included in the transmission-related information, and a step of transmitting the cellular information to the base station by the determined transmission power. And.

According to another aspect of the present invention, in a wireless communication system, a terminal that controls power for D2D communication is a transmission / reception unit that transmits / receives a signal to / from the terminal or a base station, and is related to transmission from the base station to the D2D communication. It is determined whether the transmission subframe of the cellular information that receives the information and transmits it to the base station based on the transmission-related information is a subframe that allows the D2D communication, and as a result of the determination, the transmission subframe of the cellular information is When the subframe allows D2D communication, the transmission power is determined using the first offset value included in the transmission-related information, and the cellular information is transmitted to the base station by the determined transmission power. It is characterized by including a control unit for controlling such as.

According to another aspect of the present invention, in a wireless communication system, a terminal multiplexing method for D2D communication includes uplink control including ACK or NACK for whether or not to receive forward information at any time. A step of determining whether information transmission is necessary, a stage of determining whether the information included in the uplink control information is ACK or NACK when transmission is required, and the determination result, the uplink control information. When the information included in is ACK, it is characterized by including a step of transmitting the uplink control information to the base station without transmitting the information for D2D communication.

According to another aspect of the present invention, in a wireless communication system, a terminal that multiplexes cellular information and D2 communication information transmits and receives signals to and from the terminal or base station, and forward information at any time. It is determined whether transmission of uplink control information including ACK or NACK is necessary for whether or not to receive, and when transmission is necessary, it is determined whether the information included in the uplink control information is ACK or NACK. As a result of the determination, when the information included in the uplink control information is ACK, the uplink control information is controlled to be transmitted to the base station without transmitting the information for the D2D communication.

It is a communication basic drawing of D2D. It is a reverse frequency resource used in the D2D resource. It is a flowchart which shows the autonomous cell deactivation process by one Embodiment of this invention. It is a flowchart which shows the operation procedure of the small cell which performs the network control cell deactivation procedure by one Embodiment of this invention. It is a block diagram which shows the internal structure of the transmitter apparatus of the D2D terminal by one Embodiment of this invention. It is a block diagram which shows the internal structure of the base station apparatus for power control of the D2D terminal by one Embodiment of this invention. It is a flowchart which shows the operation procedure of the terminal by one Embodiment of this invention. It is a flowchart which shows the operation procedure of the base station by one Embodiment of this invention. It is a block diagram which shows the internal structure of the terminal by another embodiment of this invention. The block diagram which shows the internal structure of the base station by another embodiment of this invention. It is a flowchart which shows the multiplexing operation procedure of the terminal by one Embodiment of this invention. It is a flowchart which shows the multiplexing operation procedure of the terminal by another embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail together with the accompanying drawings. In addition, when it is determined that a specific description of a known function or configuration related to the description of the present invention can make the gist of the present invention unnecessary, the detailed description thereof will be omitted. The terms described below are defined in consideration of the functions in the present invention, and may be changed depending on the intentions or customs of the user and the operator. Therefore, the definition must be drawn down on the basis of the content throughout this specification.

Further, in concretely explaining the embodiment of the present invention, the wireless communication system based on OFDM, particularly the 3GPP EUTRA standard, is mainly the subject, but the main gist of the present invention is a similar technical background and channel form. It can be applied to other communication systems having the present invention with a slight modification within the range without significantly deviating from the scope of the present invention, and this can be determined by a person having technical knowledge skilled in the technical field of the present invention. Let's go.

In the embodiments of the present invention described below, the base station or the cell can be used interchangeably. Further, D2D communication can be used in the sense of including all of a terminal discovery operation for discovering a terminal in contact and a direct communication in which the terminal and the terminal directly exchange information.

It has been described above that when the FDD system is assumed by the duplexing method to which the present invention is applied, D2D communication is supported by using a reverse frequency resource.

FIG. 3 is a drawing showing the resources that can be used for D2D separately using the format of the reverse resource currently supported by LTE.

In FIG. 3, 301 indicates that a plurality of subframes are gathered on the time axis. The subframe means a 10 ms time interval including a large number of symbols as the time unit used in LTE, and the subframe used in LTE is given as an example in the present invention, but the time unit is not limited to this and can be any time unit. It can be applied.

In the present invention, it is assumed that a part of the set of subframes 301 is used as a resource for D2D. In FIG. 3, regular subframes 302 are assigned for cellular communication and D2Dsubframes 303 is assigned for D2D communication.

More specifically, the resource ofD2Dsubframes303 may include some subframes in the D2D reverse resource. One subframe contains a large number of OFDM (Orthogonal Frequency Multiplexing) symbols on the time axis, or SC-FDM (single-Carrier Frequency Multiplexing) symbols, and includes several subcarriers on the frequency axis.

Then, as described above, among the subcarriers available on the frequency axis in the LTE reverse resource, as shown by 304 and 305 in FIG. 3, a large number of subcarriers located at both ends are reversed. It is used for transmission of control information (in LTE, it means Physical Uplink Resource Channel (PUCCH)). As described in the prior art, the reverse control information includes forward link channel state information (Channel Quality Information: hereinafter, CQI) of the terminal, and hybrid automatic request (hereinafter, HARQ) of forward communication. ACK / NACK information, which is response information for technology, scheduling request information for transmitting information in the reverse direction, and the like can be included.

On the other hand, D2D transmission is possible via a large number 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 is for transmitting the sounding reference signal (SRS) required for channel estimation in the reverse direction of the terminal at the base station. Can be used for. Since the transmission cycle of the SRS changes according to the setting of the base station, there may be a subframe including the SRS, and there may be a subframe not including the SRS. In the subframe without SRS, the last symbol 307 can be used in the resource for D2D, and further, there may be a case where the terminal due to the nature of D2D has to continuously transmit and receive. It is also possible to use the last symbol 307 with the required transition time while changing the operation from reception to reception or from reception to transmission.

The phenomenon of insufficient reception sensitivity (dessensing) can be described with reference to FIG. 2 based on the reverse resource shown in FIG. That is, in a situation where a terminal 205 located near an arbitrary base station 201 uses the D2D communication channel 207 to transmit to a terminal 206 far away using D2D resources, another cellular terminal 203 transmits the PUCCH 204 at the base station 201. If transmission occurs, the base station 201 may not be able to accurately receive the PUCCH 204 transmitted by the terminal 203 due to the reception sensitivity decrease phenomenon. This is because there may be a case where the reception strengths of one or more signals received by one base station 201 differ by more than a certain value. That is, when the signal 208 transmitted by the terminal 205 reaches the base station 201, a situation in which the reception strength becomes very large can occur. The present invention presents a method for solving the above-mentioned situation in which the base station cannot receive the information of the cellular terminal by the communication of the D2D terminal via the following embodiment.

First, prior to explaining the transmission power control presented in the present invention, a transmission power control method will be generally described when the transmitter and the receiver communicate with each other, particularly when the transmitter is a terminal. When the terminal transmits an arbitrary channel to the base station, the transmission power to be used can be determined by the smaller value of the following two variables.

1. Maximum usable power of the transmitter (terminal) 2. Transmission power that can match the desired received power when the receiver (base station) receives the signal transmitted by the transmitter (terminal).

Here, the maximum usable power of the transmitter, that is, the terminal can be the power that the transmitter can physically use for transmitting information, which is limited by the hardware of the terminal, or of the base station. It can be the maximum power determined by any setting. The receiver, that is, the base station, makes an effort to match the received power of the terminal with a constant value. This is to prevent the reception sensitivity decrease phenomenon when the signals of many terminals are received at the same time, and to facilitate the scheduling for the transmission of the terminals. Therefore, the terminal will limit the transmission power in order to match the reception power of the base station.

Therefore, 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 mathematical formula.

Tx_Power = min {Max_Tx_Power, f (Rx_Power)} --- (1)

In the formula (1), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum usable power of the terminal, Rx_Power is the reception power of the base station that receives the transmission signal of the terminal, and the function f (Rx_Power) is the above. The transmission power determined by the terminal when Rx_Power is defined. Although the function f (Rx_Power) can be variously determined by using the Rx_Power value, the most typical mathematical formula is as follows.

f (Rx_Power) = Rx_Power + Prop_loss--(2)

In the above equation (2), Prop_loss is a path loss due to the distance between the transmitter and the receiver, and is determined not only by the distance between the transmitters and receivers but also by the state in which the transmitter and receiver are located, the medium existing between the transmitters and receivers, and the like. To. The terminal measures the received power of the reference signal transmitted by the base station, and if the transmission power of the reference signal is measured from the base station, the path loss value between the terminal and the base station can be known. Since the path loss value is a value measured over a long period of time (long term) and it can be assumed that the path loss in the reverse direction and the path loss in the forward direction are the same, the path loss value measured in the forward direction is used. It can be used for power control of reverse transmission.

The f (Rx_Power) equation can be defined by using various variables other than the path loss value. Examples of the variable include the amount of resources of the channel to be transmitted (for example, the number of PRB (Physical Resource Block) defined in LTE), an arbitrary offset value set by the base station, and various other variables. Can be done. The f (Rx_Power) equation can be matched by giving an arbitrary weighted value to each variable. The weighted value can be changed, can be set by the base station, and can correspond to a positive value or a negative value.

In the following, a solution to the current state of decrease in reception sensitivity of a base station through power control of a D2D terminal via various embodiments will be described.

Embodiment 1: D2D channel power control In the present embodiment, the terminal performing D2D communication is the D2D link (in the present invention, the link means a radio path through which information is transmitted between a transmitter and a receiver, a radio link, a channel, and the like. When transmitting a signal via a radio channel, a connection, etc.), information transmission through the D2D link and the base station via an appropriate setting of transmission power for the D2D link. We present a method that supports all of the solutions to the phenomenon of reduced reception sensitivity.

There is an arbitrary base station and a cellular terminal, and the cellular terminal transmits arbitrary control information or data information at the base station, and D2D existing in the base station at the same time (time) or the same subframe. In a situation where the terminal is transmitting a D2D channel, the transmission power of the D2D terminal can be determined by the value of any one of the following three variables, and according to the preferred embodiment of the present invention, the three variables It can be determined by the smallest value of.

1. 1. Maximum usable power of the transmission D2D terminal (205 in FIG. 2) 2. A transmission power capable of receiving a signal transmitted by the transmission D2D terminal (205 in FIG. 2) and setting a desired reception power when the 206 in FIG. 2 is received 3. The transmission D2D terminal (in FIG. 2) When the base station (201 in FIG. 2) receives the signal transmitted by 205), the base station does not cause a decrease in reception sensitivity in receiving the signal received from another cellular terminal (203 in FIG. 2). Transmission power

The maximum usable power of the terminal can be the power that the transmitter can physically use, which is limited by the hardware of the terminal for transmitting information, or the maximum determined by any setting of the base station. It can be electric power. Further, the reason for making an effort to match the D2D channel transmitted by the transmitting D2D terminal so that the receiving D2D terminal can receive it with an appropriate received power is to facilitate scheduling for transmission of the transmitting D2D terminal. That is. The third variable is arbitrary from signals received from other cellular terminals while maintaining the received power of the D2D transmission below a certain level when it is assumed that the base station receives the D2D transmission transmitted by the transmission D2D terminal. The value does not become larger than the value of. In this case, the third variable prevents a situation in which the reception signal of the D2D terminal becomes much larger than the reception signal of the cellular terminal at the base station and the reception sensitivity of the signal of the cellular terminal is lowered. The above contents are shown in a mathematical formula as follows.

Tx_Power = min {Max_Tx_Power, f (Rx_Power_D2D), g (Rx_Power_eNB)} --- (3)

In the formula (3), Tx_Power is the transmission power of the transmission D2D terminal, Max_Tx_Power is the maximum usable power of the transmission D2D terminal, and Rx_Power_D2D is the reception power of the reception D2D terminal that receives the transmission signal of the transmission D2D terminal, Rx_Power_2NB. It can be the received power when the base station receives the transmission signal of the transmission D2D terminal.

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

The function f (Rx_Power_D2D) can be variously determined by using the Rx_Power_D2D value, but the most typical mathematical formula is as follows.

f (Rx_Power_D2D) = Rx_Power_D2D + Prop_loss_D2D --- (4)

In the above equation (4), Prop_loss_D2D is a path loss due to the distance between the transmitting D2D terminal and the receiving D2D terminal, and not only the distance between the transmitting and receiving parts but also the state where the transmitting and receiving parts are located, the medium existing between the transmitting and receiving parts, and the like. Determined by. When the transmitting D2D terminal and the receiving D2D terminal set the D2D channel, the transmitting D2D terminal knows the route loss through transmission / reception of an arbitrary promised signal and information sharing with respect to the transmission power of the promised signal.

The formula f (Rx_Power_D2D) can be defined by using various variables other than the path loss value. The variable may be the amount of resources of the channel to be transmitted (eg, the number of PRBs (Physical Resolution Blocks) defined in LTE), or any set at the base station or set via channel settings between D2D terminals. Offset values and various other variables can be given as examples. The f (Rx_Power_D2D) equation can be matched by giving an arbitrary weighted value to each variable. The weighted value can be changed, can be set by the base station or can be set between D2D terminals via channel setting, and can correspond to a positive value or a negative value.

The function g (Rx_Power_eNB) can be variously defined using the Rx_Power_eNB value, and the most typical mathematical formula is as follows.

g (Rx_Power_eNB) = Rx_Power_eNB + Prop_loss_eNB + Desense_Offset --- (5)

In the above equation (5), Prop_loss_eNB is a route loss due to the distance between the transmission D2D terminal and the base station, and not only the distance between the transmission D2D terminal and the base station but also the state where the transmission D2D terminal and the base station are located, the transmission D2D. Determined by the medium existing between the terminal and the base station, the transmission D2D terminal measures the reception power of the reference signal transmitted by the base station, measures the transmission power of the reference signal from the base station, and transmits the transmission D2D. You can see the route loss value of the terminal and the base station.

The sense offset (Desense_Offset) can be defined as a value adjusted so that the base station does not reduce the reception sensitivity when receiving the D2D signal and a signal from another cellular terminal together. The desense offset (Desense_Offset) can be determined by an arbitrary value in consideration of the performance of the receiver of the base station, and can be set by the base station and notified to the transmission D2D terminal.

The g (Rx_Power_eNB) equation can be defined using various variables other than the path loss value. Examples of the variable include the amount of resources of the D2D channel to be transmitted (for example, the number of PRBs (Physical Resource Blocks) defined in LTE), an arbitrary offset value set by the base station, and various other variables. Can be done. The g (Rx_Power_eNB) equation can be matched by giving an arbitrary weighted value to each variable. The weighted value can be changed, can be set by the base station, and can correspond to a positive value or a negative value.

The operation flowchart of the terminal and the base station according to the 1st Embodiment of this invention is shown below.

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

FIG. 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 404 steps. Base station information can also be used in 404 steps. For example, in order for D2D transmitting / receiving terminals to discover each other (discovery), perform scheduling, and actually transmit data, synchronization between them should be achieved, and the synchronization is a synchronization signal (PSS,) transmitted by a base station. It can be done using SSS) or the like.

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

In FIG. 4, it is shown that the base station that gives power control-related information to the transmitting D2D terminal 401 and the base station that gives power control-related information to the receiving D2D terminal 402 are the same base station 403, but it is always limited to this. Instead, for example, when the base stations to which each D2D terminal belongs are different base stations, they may be different base stations.

The transmitting D2D terminal 401 and the receiving D2D terminal 402 can then determine the path loss for the D2D channel. The determination for the path loss can also be determined in advance in 404 steps. The determination for the path loss can be shared between the transmitting D2D terminal 401 and the receiving D2D terminal 402 via a 407-step reference signal transmission and a 408-step reference signal measurement path loss calculation and measurement report. The transmission D2D terminal 401 can transmit the D2D channel in 409 steps by using the following formula.

Tx_Power = min {Max_Tx_Power, f (Rx_Power_D2D), g (Rx_Power_eNB)} --- (6)

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

The storage unit 501 may store the set value related to the power control received from the base station, that is, the information used when determining f (Rx_Power_D2D) or the information used when determining g (Rx_Power_eNB). it can.

The 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 formula and sends the power amplifier to the power amplifier via the control signal 503. Input the transmission power of the D2D channel.

On the other hand, in the D2D channel generator 504, a signal is generated in which the information transmitted via the D2D channel is wirelessly transmitted via channel coding, modulation, or the like. The signal is amplified by the power amplifier 505. At this time, the power control controller 502 determines the position to be amplified by using the control signal 503. The signal amplified by the power amplifier 505 is transmitted wirelessly via the transmission unit 506.

In the above, the power controller 502 and the D2D channel generator 504 are shown by being divided into separate blocks, but it is not always necessary to be divided into physically divided hardware as described above, and the detailed function block performed by the control unit. It can also be embodied in.

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

The D2D power control-related setting value determination unit of the base station determines the 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). Further, the D2D power control-related setting value determination unit of the base station determines the power control-related setting value required when the base station receives the D2D channel (602). The power control related setting value may include information used when determining g (Rx_Power_eNB).

The two set values are signaled to the D2D terminal via the transmission unit 603. The signaling procedure is shown in step 405 of FIG. In FIG. 6, the determination unit of the D2D power control related setting value is shown by dividing it into two blocks, but it is not always necessary to divide it into the physically divided hardware as described above, and the control unit performs it. It should be noted that it can also be embodied in a detailed functional block.

Embodiment 2: Power control of the cellular channel when the D2D channel exists In the second embodiment of the present invention described below, the reception of the cellular terminal by the D2D link reception of the D2D terminal existing at the position where the base station is in contact is received. Cellular terminals present new power control methods to solve the problem of reduced sensitivity.

It has been explained above that when a cellular terminal transmits information using a cellular channel in the opposite direction, the transmission power is used at a value determined by the following mathematical formula.

Tx_Power = min {Max_Tx_Power, f (Rx_Power)} --- (7)

In the formula (7), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum usable power of the terminal, Rx_Power is the reception power of the base station that receives the transmission signal of the terminal, and the function f (Rx_Power) is the above. The transmission power determined by the terminal when Rx_Power is defined.

In the present embodiment, the cellular terminal presents a method of setting the transmission power using another mathematical formula depending on the presence or absence of the D2D terminal.

That is, when the D2D terminal exists near the base station and the base station receives the transmission of the cellular terminal, the cellular terminal causes the D2D terminal to prevent the problem of lowering the reception sensitivity from occurring due to the D2D terminal. In some cases, it includes a method of adding an additional offset to the transmission power and transmitting with a stronger transmission signal. The present embodiment according to the above description can be expressed by the following mathematical formula.

Tx_Power = min {Max_Tx_Power, f (Rx_Power) + offset_D2D} --- (8)

In the formula (8), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum usable power of the terminal, Rx_Power is the reception power of the base station that receives the transmission signal of the terminal, and the function f (Rx_Power) is the above. When Rx_Power is defined, the terminal can be the communication power determined by it. Finally, the variable offset_D2D is an offset having another value depending on the presence or absence of the D2D terminal that simultaneously transmits the cellular terminal when the cellular terminal transmits arbitrary data information or control information.

In general, it is possible to set a larger offset_D2D value than when there are D2D terminals transmitting at the same time and when not. In one example, when a D2D terminal exists, it can be used with offset_D2D (first offset) = 5 dB, and when a D2D terminal does not exist, it can be used with offset_D2D (second offset) = 0 dB.

The effect of offset_D2D can be obtained by additionally setting different variables existing in f (Rx_Power). The PUCCH f (Rx_Power) equation can be set as follows.

here

Variables such as are variables that are set for PUCCH performance in the upper hierarchy, but one or more variables in this variable are divided into two sets and one used in general subframes where D2D is not set. Set one set and another set used in the subframe where D2D is set. The terminal currently determines whether or not D2D exists in the subframe that transmits PUCCH, selects one of the two variables or variable sets set, substitutes it in the above formula, and uses it for PUCCH power setting. be able to.

The office_D2D value can be set by the base station via signaling, or can be determined by an arbitrary value. Alternatively, it is possible to add to the conventionally set DCI (Downlink Control Information) format, define a new DCI format, and notify the terminal of the offset_D2D value via the newly defined DCI format. For example, the offset_D2D value can be transmitted to the terminal via a physical downlink channel (Physical Downlink Control Channel). Alternatively, the information can be transmitted to the terminal using fields reserved in any of the conventional defined DCI formats without defining a new DCI format, and any of the conventional defined DCI formats. It is also possible to define the field to have a different interpretation and send the offset_D2D value to the terminal.

On the other hand, in the formula (9), the function f (Rx_Power) can be determined by the method described above.

On the other hand, since it is possible to know whether or not the cellular terminal simultaneously transmits the D2D terminal, the base station can notify all the terminals belonging to the base station of the subframe in which the D2D channel exists by using the system information. it can. Further, the base station can also notify each terminal of the transmission time of the D2D terminal, and in this case, the terminal can be notified via higher-level signaling or physical layer control information.

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

The cellular terminal starts operation in the 701 step and acquires the D2D transmission related information, for example, the information about when the D2D transmission is made via which subframe, and the offset_D2D information by the D2D transmission in the 702 step.

The information for 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 used.

Further, regarding the offset_D2D information by D2D transmission, if the D2D terminal exists, it is assumed that the offset_D2D = A, and if the D2D terminal does not exist, the value for (A, B) is assumed to be the terminal. Can be set with.

The D2D transmission-related information can be obtained from system information via a broadcast channel (broadcast channel), and can be set and notified by a base station for each terminal.

In this case, higher layer signaling such as RRC can be used.

Offset_D2D information can be found via system information. Alternatively, the base station can notify the offset_D2D information for each terminal. In this case, higher layer signaling such as RRC can be used. Alternatively, the base station may define a new DCI format including the D2D transmission-related information and the office_D2D information, and the base station may transmit the information to the terminal via the PDCCH. Alternatively, the base station may transmit the information to the terminal using a field reserved in any of the conventional defined DCI formats without defining a new DCI format. It is also possible to send the offset_D2D value to the terminal by defining it to have a different interpretation for any field in the conventional defined DCI format.

Next, the cellular terminal goes to the cellular information, that is, the base station in 703 steps.

The information to be transmitted is prepared, and then in the 704 step, the D2D transmission-related information acquired in the 702 step is used to determine whether the D2D transmission is performed together at the time when the cellular information is transmitted. For example, the terminal can determine whether the subframe for transmitting cellular information is a subframe that allows D2D transmission.

As a result of the determination, when the D2D transmission is combined, the terminal proceeds to the 705 stage and sets_D2D = A, that is, an offset value required when the D2D transmission exists. On the other hand, when D2D transmission does not occur together, the terminal proceeds to the 706 stage and sets offset_D2D = B, that is, an offset value required when D2D transmission does not exist.

Next, the terminal determines the transmission power using the offset_D2D value set in 707 steps and the following mathematical formula.

Tx_Power = min {Max_Tx_Power, f (Rx_Power) + offset_D2D} --- (10)

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

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

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

The terminal can obtain the D2D transmission-related information from the system information via a broadcast channel (broadcast channel), and the base station can notify each terminal. Similarly, the terminal can know the office_D2D from the system information, or the base station can set and notify each terminal. As another embodiment thereof, a new DCI format including the D2D transmission-related information and offset_D2D information can be defined, and the base station can transmit the information to the terminal via the PDCCH. Alternatively, the information can be transmitted to the terminal using a field reserved in any of the conventional defined DCI formats without defining a new DCI format, and any of the conventional defined DCI formats. The offset_D2D value can also be sent to the terminal by defining different interpretations for the field of.

The operation is finished in 804 steps.

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

Whether or not D2D transmission is performed is determined by the determination machine 901 whether or not D2D transmission exists. The power control-related setting value storage device 902 stores the power control-related setting value received from the base station. When the determination information of the D2D transmission availability determination machine 901 and the information stored in the storage device 902 of the power control related setting value are input 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 storage device 902 of the power control-related set value, and the cellular transmission power controller 903 determines the accurate offset_D2D according to the determination of the D2D transmission possibility determination machine 901. The channel to be transmitted by the terminal is generated by the cellular channel generator 905 and amplified via the power amplifier 906, but the amplified value is the value determined by the cellular transmission power controller 903 and is input to the power amplifier 906 904. Will be decided. The amplified cellular information is transmitted via the transmission unit 907.

Each block shown in FIG. 9 does not necessarily have to be divided into physically divided hardware, and can be embodied in a detailed functional block performed by the control unit.

FIG. 10 is a block diagram showing an internal structure of the base station apparatus according to the 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 via the transmission unit 1003.

From the following, a method for multiplexing D2D information and cellular information presented in another embodiment of the present invention will be described.

Problems in a situation where a cellular terminal transmits cellular information to a base station in the opposite direction and a D2D terminal transmits it to another D2D terminal using the same reverse frequency resource, and a solution through power control of the D2D terminal or the cellular terminal. Described for.

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

The cellular transmission can include data transmission, and can also include ACK / NACK transmission by forward data transmission, CQI transmission, and scheduling request information.

In yet another embodiment of the present invention described below, it is attempted to propose a solution in the case where the transmission of the cellular information and the transmission / reception of the D2D information described above occur at the same time.

Embodiment 3: Simultaneous transmission of cellular channel and D2D channel In the present embodiment, one terminal transmits reverse cellular information to a base station via the cellular channel, and at the same time, D2D information is transmitted to another D2D terminal via the D2D channel. Suppose the sending situation. The terminal uses a single carrier frequency division method (Single Carrier Frequency Division Multiple Access: hereinafter, SC-FDMA) transmission method.

Therefore, it is assumed that the number of channels transmitted by one terminal at the same time is limited to one. If the terminal must transmit the cellular channel and the D2D channel at the same time, the following operations are possible. Preferably, any one of the operations described later can be selected and performed.

1. 1. Only the D2D channel is transmitted.
2. Send only cellular channels.
3. 3. One of the D2D channel and the cellular channel is selected and transmitted according to the setting of the base station. (In this case, the base station gives priority to which channel when simultaneous transmission / reception of the D2D channel and the cellular channel occurs via system information, upper layer signaling such as RRC signaling, or control information of the physical layer. That information can be transmitted to the terminal.)
4. Two channels are transmitted at the same time, ignoring the SC-FDMA system. At this time, the transmission power is first assigned to the cellular channel, and the remaining transmission power is assigned to the D2D channel.

Embodiment 4: Selective transmission of cellular channel and D2D channel by ACK / NACK In the present embodiment, one terminal transmits reverse cellular information including ACK / NACK at a base station via the cellular channel, and simultaneously transmits a D2D channel. It is assumed that the D2D information is transmitted by another D2D terminal via the terminal.

When the terminal transmits information for ACK / NACK at the base station, it means that the base station notifies via ACK / NACK whether or not the forward information received in advance by the terminal is properly received. Means that.

If the information transmitted by the terminal to the base station is ACK among ACK / NACK, that is, if the ACK information is always transmitted to the base station when the reception for the forward information is accurate, additional retransmission is performed. Can be prevented. On the other hand, if the information transmitted by the terminal at the base station is NACK among ACK / NACK, the base station retransmits the forward information even if the NACK information is not transmitted to the base station, so the ACK information must be transmitted. The need to send NACK information is less than the need to have to.

Therefore, in the present embodiment, when one terminal transmits reverse cellular information including ACK / NACK at the base station via the cellular channel and at the same time transmits D2D information at another D2D terminal via the D2D channel, the above-mentioned Considering the importance of ACK and NACK, if the ACK / NACK information is ACK, the D2D channel is not transmitted and only the cellular channel is transmitted. If the ACK / NACK information is NACK, the cellular channel is not transmitted and only the D2D channel is transmitted. Suggest a way to send.

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

If the operation of the terminal is started at the 1101 stage of FIG. 11, preparations for transmission of D2D information are performed at the 1102 stage. At the 1103 stage, if necessary, the transmission for cellular information is prepared. In this case, the information included in the PUCCH can be included in the information for preparing the transmission in 1103 steps.

Next, the terminal determines whether the uplink control information (PUCCH) needs to be transmitted in the 1104 step, and if the PUCCH transmission is not necessary, the terminal transmits the D2D information in the 1106 step. On the other hand, if it is determined in the 1104 step that the PUCCH transmission is necessary, the 1105 further determines whether or not the ACK / NACK information included in the PUCCH is ACK or NACK.

At this time, if the ACK / NACK information is ACK, the terminal proceeds to the 1107 step and transmits the PUCCH. On the other hand, when the ACK / NACK information is NACK, the terminal proceeds to the 1106 step and transmits the D2D information.

The 1106 step transmits D2D information but does not transmit PUCCH information, and the 1107 step transmits PUCCH information but does not transmit D2D information.

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

Embodiment 5: Cellular channel-transmission and D2D channel reception are selected at the same time.

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

The terminal cannot transmit and receive at the same time via the same band. Therefore, in the present invention, when the terminal must simultaneously perform the transmission of the cellular channel and the reception of the D2D channel, the following operations are possible. Preferably, any one of the operations described later can be selected and performed.

1. 1. Receives only the D2D channel.
2. Send only cellular channels.
3. 3. Select one of D2D channel reception and cellular channel transmission according to the base station settings. (In this case, which operation of the transmission of the cellular channel and the reception of the D2D channel is given priority by the base station via system information, upper layer signaling such as RRC signaling, or control information of the physical layer. Information can be transmitted to the terminal.)

Embodiment 6: Selection for transmission of cellular control information and reception of D2D channel depending on the type of cellular control information.

In the present embodiment, it is assumed that one terminal transmits reverse cellular information including ACK / NACK at a base station via a cellular channel, and at the same time receives D2D information from another D2D terminal via a D2D channel.

When the terminal transmits ACK / NACK information at the base station, the terminal notifies the base station of information regarding whether or not the forward information received from the base station is properly received via ACK / NACK. It means that.

If the information transmitted by the terminal at the base station is ACK among ACK / NACK, that is, if the reception for the forward information is accurate and the ACK information is always transmitted to the base station, additional retransmission is performed. Can be prevented. On the other hand, if the information transmitted by the terminal at the base station is NACK among ACK / NACK, the base station retransmits the forward information even if the NACK information is not transmitted to the base station, so the ACK information must be transmitted. The need to send NACK information is less than the need to have to.

Therefore, in the present embodiment, when one terminal transmits reverse cellular information including ACK / NACK at the base station via the cellular channel and at the same time transmits D2D information at another D2D terminal via the D2D channel, the above-mentioned Considering the importance of ACK and NACK, if the ACK / NACK information is ACK, the D2D channel is not received and the cellular channel is transmitted, and if the ACK / NACK information is NACK, the cellular channel is not transmitted and the D2D channel is received. To do.

The operation procedure of the terminal according to the present embodiment is shown with reference to FIG. 12 below.

If the operation of the terminal is started at the 1201 stage of FIG. 12, the preparation for receiving the D2D information is performed at the 1202 stage, and if necessary at the 1203 stage, the transmission for the cellular information is prepared. The 1203 step cellular information can include information contained in PUCCH. The terminal determines in 1204 steps whether PUCCH transmission is required. As a result of the determination, if PUCCH transmission is not necessary, D2D information is received in 1206 steps.

On the other hand, if it is determined in the case where the PUCCH transmission is required in the 1204 step, it is determined in 1205 whether the ACK / NACK information included in the PUCCH is ACK. At this time, if the ACK / NACK information is ACK, the terminal proceeds to the 1207 stage and transmits the PUCCH. On the other hand, when the ACK / NACK information is NACK, the terminal proceeds to the 1206 step and receives the D2D information.

The 1206 stage receives D2D information but does not transmit PUCCH information, and the 1207 stage transmits PUCCH information but does not receive D2D information. When the 1206 step or the 1207 step is completed, the operation of the terminal is terminated at the 1208 step.

According to the above-described embodiment of the present invention, it is possible to control the transmission power of the terminal that performs D2D communication to prevent the situation where the reception sensitivity decrease phenomenon occurs in the existing terminal that performs cellular communication as much as possible. According to still another embodiment of the present invention, it is possible to clearly define the operation of a terminal when one terminal performs cellular communication and D2D communication at the same time.

The embodiments of the present invention disclosed in the present specification and the drawings present specific examples in order to easily explain the technical contents of the present invention and assist the understanding of the invention, and limit the scope of the present invention. It is not something to do. It is obvious to those who have ordinary knowledge in the technical field to which the present invention belongs that other modifications based on the technical idea of the present invention can be implemented in addition to the embodiments disclosed herein. is there.

401 Transmission D2D terminal 402 Reception D2D terminal 403 Base station 501 Storage unit 502 Power control controller 503 Control signal 504 Channel generator 505 Power amplifier 506 Transmission unit 603 Transmission unit 901 Transmission enable / disable judgment machine 902 Storage device 903 Cellular transmission power controller 904 Input 905 Cellular Channel Generator 906 Power Amplifier 907 Transmitter 1001 Transmission Time Information Generator 1002 Cellular Transmission Related Information Generator 1003 Transmitter

Claims (12)

In the method performed by the first terminal of the wireless communication system,
At the stage of confirming whether uplink transmission and sidelink transmission are set in the subframe,
When the uplink transmission is not set in the subframe, the step of transmitting the sidelink transmission to the second terminal in the subframe and the stage of transmitting the sidelink transmission to the second terminal.
When the uplink transmission and the sidelink transmission are set in the subframe, the step of transmitting the uplink transmission to the base station in the subframe is included.
A method , characterized in that, when the uplink transmission and the sidelink transmission are set in the subframe, the sidelink transmission is not transmitted to the second terminal. The side link transmission, discovery signals, characterized in that it comprises at least one of control information and data information, methods who claim 1. The side link transmission, characterized in that it is transmitted on the basis of a small transmission power of the first transmission power and the second transmission power, technique better of claim 1. The method further comprises the step of receiving power control related information from the base station.
The first transmission power, the number of allocated resource blocks, characterized in that it is determined based on the path loss and the received power control-related information, method who claim 3. The second transmission power, characterized in that the side links is the maximum possible transmission power for transmission, methods who claim 3. The path loss, on the basis of the information provided by the signaling of the base station, characterized in that it is determined for the serving cell, methods who claim 4. In the first terminal of the wireless communication system
A transmitter / receiver set to transmit and receive signals,
Including a control unit connected to the transmission / reception unit
The control unit
Check if uplink transmission and sidelink transmission are set in the subframe,
When the uplink transmission is not set in the subframe, the sidelink transmission is transmitted to the second terminal in the subframe.
When the uplink transmission and the sidelink transmission are set in the subframe, the uplink transmission is set to be transmitted to the base station in the subframe.
A first terminal, characterized in that, when the uplink transmission and the sidelink transmission are set in the subframe, the sidelink transmission is not transmitted to the second terminal. The first terminal according to claim 7, wherein the side link transmission includes at least one of a discovery signal, control information, and data information. The first terminal according to claim 7, wherein the side link transmission is transmitted based on the smaller transmission power of the first transmission power and the second transmission power. The control unit
Further configured to receive power control related information from the base station,
The first terminal according to claim 9, wherein the first transmission power is determined based on the number of allocated resource blocks, the route loss, and the received power control-related information. The first terminal according to claim 9, wherein the second transmission power is the maximum possible transmission power for the side link transmission. The first terminal according to claim 10, wherein the route loss is determined for the serving cell based on the information provided by the signaling of the base station.