JP2019068486A - Method and apparatus for power control and multiplexing for executing d2d communication in wireless cellular communication system - Google Patents

Abstract

To provide a method and an apparatus for power control for executing D2D communication in a wireless cellular communication system.SOLUTION: A power control method of a terminal for device-to-device (D2D) communication in a wireless system includes the steps of: receiving power control related information for the D2D communication from a base station; determining transmission power of the terminal on the basis of maximum available power of the terminal and the received power control related information for the D2D communication; and transmitting data according to the determined transmission power.SELECTED DRAWING: Figure 4

Description

  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 where D2D communication technology and wireless cellular communication technology are mixed and used, and a corresponding base Station operation and these devices.

  The wide variety of services using wireless mobile communication systems will require a need for new technologies to support emerging services more efficiently, thereby leading to new methods within wireless mobile communication systems And technologies are being developed and studied.

  Device-to-terminal (Device to Device, D2D) communication is a new technology that appears as a solution to new services, and D2D communication is basically direct communication with other terminals in which any terminal is present around the terminal. Technology that allows people to Using D2D communication technology, terminals can discover what terminals are present around them, and can perform direct communication with terminals that need to communicate.

  If D2D comes to perform direct communication, it will use relatively less radio resources compared to performing communication using a base station using an existing radio network, which is large in terms of radio resource efficiency It comes to have a merit. In addition, a method that enables the discovery of a terminal around a terminal is supported, so that the terminal can directly provide necessary information to the desired terminal, advertising service, social network service (Social Networking Service: It will be possible to greatly increase the efficiency in supporting SNS) and the like.

  At present, the Long Term Evolution-Advanced (hereinafter referred to as LTE-A) system also requires support for D2D technology, and technical debates on it are in progress.

  FIG. 1 is a diagram illustrating a scenario in which D2D communication is supported in a cellular system.

  The base station 101 manages terminals 103 and 104 in a cell 102 controlled by the base station. The terminal 103 performs cellular communication using the link 106 between the base station 101 and the terminal-base station, and the terminal 104 performs cellular communication using the link 107 between the base station 101 and the terminal-base station. It will 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 LTE-A system basically does not cause maximum damage to terminals using existing cellular systems. Assume that it is executed in the direction. For this purpose, resources for non-overlapping radio resources are used for D2D communication separately from radio resources used by a cellular terminal (in the present invention, a cellular terminal refers to a terminal that performs existing terminal-to-base station communication rather than D2D communication). It can also be considered that the resources used by the cellular terminals are likewise used by the D2D terminals but without giving maximum interference to each other.

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

  In the FDD, forward and reverse directions are classified by using other frequency resources. When D2D communication is used separately from existing cellular communication resources in a system using the FDD, there is a tendency that the method of using the reverse frequency resource with D2D among the forward direction and reverse direction resources is generally prioritized is there. This is because in the FDD system, more types of signals are multiplexed on the forward frequency resource than the reverse frequency resource, and it is difficult to separately allocate the resource in the D2D communication application as compared to the reverse resource.

  Also, in an FDD system that considers only existing cellular terminals, forward traffic tends to be higher than in the reverse direction due to the characteristics of communication services, and overhead transmitted in the forward direction is greater than in the reverse direction. The frequency usage burden on forward resources is generally greater than the frequency usage burden on reverse resources.

  Therefore, if forward resources are allocated and used for D2D communication applications, the burden on the forward resources becomes greater, and it becomes difficult to balance forward and reverse frequency resource usage.

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

  The control information transmitted in the reverse direction includes forward link channel state information (Channel Quality Information: hereinafter referred to as CQI) of a terminal, and Hybrid Automatic ReQuest (hereinafter referred to as HARQ) technology for forward communication. ACK / NACK information, which is response information, and scheduling request information for transmitting reverse direction information may be included.

  The control information is transmitted from any terminal in the reverse direction, ie, to the base station. In the case where only the cellular terminal communicates in the reverse direction resource, of course, the transmission of the control information can occur even when the D2D terminal communicates between the terminals. That is, there may occur a case where a plurality of D2D terminals communicate with each other at the same time in the same cell (in the same subframe in LTE as an example) and the cellular terminal transmits control information to the base station it can. In the above case, it may be assumed that the frequency resource used by the cellular terminal to transmit 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 diagram illustrating a scenario in which a cellular terminal and a D2D terminal in the same cell simultaneously transmit and receive signals with a base station using reverse resources in the same subframe.

  The base station 201 has a cell and the terminals 203, 205, 206 are located in the cell. Terminal 203 is transmitting reverse control information at the cellular terminal using reverse resource 204. The terminal 205 is performing D2D communication with the terminal 206, and the terminal 205 can transmit information using the D2D link 207 at the terminal 206. At this time, the terminal 203 appropriately sets transmission power for information transmission such that the base station 201 has appropriate reception power when receiving the reverse control information. Also, 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, when the distance between the terminal 205 and the terminal 206 is increased, the terminal 205 may set a large transmission power to perform D2D transmission so that transmission to the terminal 206 becomes proper. At this time, when the terminal 205 is positioned to be in close contact with the base station 201, the D2D transmission that the terminal 205 transmits to the terminal 206 can be received by the base station 201 with a very large received power.
At this time, if the reception power received by the base station 201 from the terminal 205 (see 208) is greater than a certain value as compared to the signal transmitted by the cellular terminal 203 in the reverse direction, reception sensitivity is insufficient in receiving the signal ( There is a risk that a problem may occur in which the base station 201 can not receive the reverse direction control information transmitted by the terminal 203 due to the occurrence of the phenomenon of “descending”.

International Publication No. 2012/166969 JP-T 2010-504048 U.S. Patent Application Publication No. 2012/0269072

  In the case where the cellular terminal and the D2D terminal included in one base station simultaneously transmit using the reverse frequency resource, the difference in received signal strength between the base station and the cellular terminal and the D2D terminal becomes large. We described the problem that we can not receive the information sent from the terminal. The present invention attempts to describe the power control procedure of the D2D terminal and the operation of the associated base station and terminal in order to solve the problem due to the reception insufficiency in the scenario described above.

  The present invention has been made to solve the above-mentioned problems, and according to one aspect of the present invention, the terminal and the cellular terminal using D2D technology in the mobile communication system have the problem of degradation of reception sensitivity between each other. Power control procedure of D2D channel necessary to perform communication simultaneously, a procedure in which one terminal simultaneously transmits D2D data and cellular data, and a method of operating base station and terminal to support the procedure And provide an apparatus.

  According to one aspect of the present invention, in a wireless communication system, a method of controlling power of a terminal for D2D communication comprises: receiving power control related information for D2D communication from a base station; Determining the transmission power of the terminal based on the available power and the received power control related information for D2D communication, and transmitting data according to the determined transmission power. It features.

   According to another aspect of the present invention, in the wireless communication system of the present invention, a terminal that controls power for D2D communication is a transmitting / receiving unit that transmits / receives a signal to / from the terminal or the base station; Receiving power control related information for communication, determining the transmission power of the terminal based on the maximum available power of the terminal and the power control related information for the received D2D communication, the determined transmission power And a control unit configured to control to transmit data according to.

  According to another aspect of the present invention, in a wireless communication system, a method of controlling power of a terminal for D2D communication comprises: receiving transmission related information for the D2D communication from a base station; and based on the transmission related information. Determining whether a transmission subframe of cellular information to be transmitted to the base station is a subframe permitting the D2D communication, and a case where the transmission subframe of cellular information allows the D2D communication as a result of the determination Determining a transmission power using a first offset value included in the transmission related information, and transmitting the cellular information to the base station according to the determined transmission power. I assume.

  According to another aspect of the present invention, in a wireless communication system, a terminal controlling power for D2D communication is a transmitting / receiving unit transmitting / receiving a signal to / from the terminal or base station, and transmission related to the D2D communication from the base station. Information is received, and it is determined whether a transmission subframe of cellular information to be transmitted to the base station is a subframe that permits the D2D communication based on the transmission related information, and as a result of the determination, the transmission subframe of cellular information is If it is a subframe that allows the D2D communication, a transmission power is determined using a first offset value included in the transmission related information, and the cellular information is transmitted to the base station according to the determined transmission power. And a control unit for controlling.

  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 receiving forward information at any time. Determining whether it is necessary to transmit information, and, when it is necessary to transmit, determining whether the information included in the uplink control information is ACK or NACK, and the determination result, the uplink control information And transmitting the uplink control information to the base station without transmitting information for D2D communication when the information contained in the ACK is an ACK.

  According to another aspect of the present invention, in a wireless communication system, a terminal for multiplexing cellular information and D2 communication information includes a transmitting / receiving unit for transmitting / receiving a signal to / 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 according to whether to receive or not, and when transmission is required, it is determined whether the information included in the uplink control information is ACK or NACK, As a result of the determination, if the information included in the uplink control information is an ACK, control is performed to transmit the uplink control information to the base station without transmitting information for D2D communication.

It is a communication basic drawing of D2D. It is a reverse frequency resource used by the resource of D2D. 5 is a flowchart illustrating an autonomous cell deactivation process according to an embodiment of the present invention. 5 is a flowchart illustrating an operation procedure of a small cell performing a network control cell deactivation procedure according to an embodiment of the present invention. FIG. 2 is a block diagram showing an internal structure of a transmitter apparatus of a D2D terminal according to an embodiment of the present invention. FIG. 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. 5 is a flowchart illustrating an operation procedure of a terminal according to an embodiment of the present invention. 5 is a flowchart illustrating an operation procedure of a base station according to an embodiment of the present invention. FIG. 7 is a block diagram illustrating an internal structure of a terminal according to another embodiment of the present invention. FIG. 7 is a block diagram showing an internal structure of a base station according to another embodiment of the present invention. 5 is a flowchart illustrating a multiplexing operation procedure of a terminal according to an embodiment of the present invention. 5 is a flowchart illustrating a multiplexing operation procedure of a terminal according to another embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. Further, in the description of the present invention, when it is determined that the specific description of the related known function or configuration can make the gist of the present invention unnecessary, the detailed description thereof will be omitted. And, the terms to be described later are terms defined in consideration of the functions in the present invention, which can be changed according to the intention or convention of the user or the operator. Therefore, the definition should be based on the contents throughout the present specification.

  Also, in describing the embodiments of the present invention, OFDM based wireless communication systems, especially the 3GPP EUTRA standard, are mainly targeted, but the main gist of the present invention has similar technical background and channel configuration. The present invention can be applied to other communication systems having the same without departing from the scope of the present invention in a range of minor variations within the scope, which can be determined by those skilled in the art of the present invention. I will.

  In the embodiments of the invention described hereinafter, base stations or cells can be used interchangeably. Also, D2D communication can be used in the sense that it includes both a terminal discovery operation of discovering a connected terminal and direct communication in which a terminal and a terminal directly exchange information.

  It has been described above that D2D communication is supported using reverse frequency resources when assuming an FDD system in a duplexing method to which the present invention is applied.

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

  In FIG. 3, reference numeral 301 denotes 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 a time unit used in LTE, and in the present invention, a subframe used in LTE is taken as an example, but it is not limited thereto and may be any time unit. It can be applied.

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

  Specifically, the resource of D2D subframes 303 may include some subframes 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-DDM) symbol in a time axis, and includes several subcarriers in a frequency axis.

  Then, as described above, in the LTE reverse resources, among the subcarriers available on the frequency axis, 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 Control Channel (PUCCH)). In the reverse control information, as described in the above-mentioned prior art, forward link channel state information (Channel Quality Information: hereinafter referred to as CQI) of a terminal, hybrid automatic retransmission of forward communication (following referred to as HARQ below) ACK / NACK information, which is response information for the technology, and scheduling request information for transmitting reverse direction information may 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 portions at both ends of the subframe. At this time, the last OFDM symbol (or SC-FDM symbol) located in each subframe is for transmission of a sounding reference signal (SRS) required for channel estimation in the reverse direction at the base station. Can be used. The SRS may be transmitted in different subframes depending on the setting of the base station, and may include subframes in which the SRS is included, and subframes in which the SRS is not included. In the subframes without SRS, the last symbol 307 can be used in the D2D resource, and there may be a case where the terminal in the nature of D2D must transmit and receive continuously, but at this time, transmission It is also possible to use the last symbol 307 with a transition time that is required while changing the operation from Q.2 to reception or from the reception to transmission.

  Based on the reverse direction resources shown in FIG. 3, the de-sensing phenomenon may be described with reference to FIG. That is, another cellular terminal 203 uses the PUCCH 204 at the base station 201 in a situation where the terminal 205 located near any base station 201 transmits using the D2D communication channel 207 to the distant terminal 206 using D2D resources. If transmission is to be performed, a situation occurs in which the base station 201 can not correctly 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 may differ by more than a predetermined value. That is, when the signal 208 transmitted by the terminal 205 reaches the base station 201, a situation may occur where the reception strength becomes very large. The present invention presents a method for solving the above situation where the base station can not receive the information of the cellular terminal by the communication of the D2D terminal through the following embodiments.

  First, prior to describing the transmission power control presented in the present invention, a transmission power control method will be described generally in the case where the transmitter and the receiver communicate, 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.

One. Maximum available power of transmitter (terminal) 2. Transmission power that can match the desired reception power when a receiver (base station) receives a signal transmitted by the transmitter (terminal)

  Here, the maximum available power of the transmitter, ie the terminal, can also be the physically available power that the transmitter is limited by the hardware of the terminal for transmitting information, or of the base station It can be the maximum power defined by any setting. The receiver, ie, the base station will make an effort to adjust the received power of the terminal at a constant value. This is to prevent the reception desensitization phenomenon when signals of many terminals are simultaneously received, and to facilitate scheduling for transmission of the terminals. Therefore, the terminal limits the transmission power to match the reception power of the base station.

  Therefore, the transmission power of the terminal can be determined by the 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)} --- (1)

  In Equation (1), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum available power of the terminal, Rx_Power is the reception power of the base station receiving the transmission signal of the terminal, and the function f (Rx_Power) is the above It is a transmission power determined by the terminal when Rx_Power is determined. Although the function f (Rx_Power) can be determined variously using the Rx_Power value, the most representative equation is as follows.

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

  In the 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 transmitter and receiver but also by the state in which the transmitter and receiver are located and the existing medium between the transmitter and receiver Ru. If the terminal measures the received power of the reference signal transmitted by the base station and measures the transmission power of the reference signal from the base station, path loss values of the terminal and the base station can be obtained. Since the path loss value is a value measured over a long term, and it is assumed that the reverse and forward path losses can be assumed to be the same, the forward path loss value measured It can be used for reverse transmission power control.

  The f (Rx_Power) equation can be defined using various variables other than the path loss value. The variable may be, for example, an amount of resources of a channel to be transmitted (for example, the number of PRBs (Physical Resource Blocks) defined in LTE), an arbitrary offset value set in a base station, and various other variables. Can. The f (Rx_Power) formula can take a method of giving an arbitrary weight value to each variable and combining them. The weight may be changed, may be set by the base station, and may correspond to a positive value or a negative value.

  The following describes a solution to the current situation of receiving sensitivity reduction of a base station through power control of a D2D terminal through various embodiments.

Embodiment 1: D2D Channel Power Control In the present embodiment, a terminal performing D2D communication is the D2D link (in the present invention, a link means a radio path through which information is transmitted between a transmitter and a receiver). Can be used in the same sense as a radio channel, connection, etc.) when transmitting information through the D2D link and the base station via the appropriate setting of the transmit power for the D2D link. We propose a method to support all of the reception sensitivity reduction phenomenon solution.

  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 or in the same subframe. In a situation where a terminal is transmitting a D2D channel, the transmission power of the D2D terminal can be determined by one of the following three variables, according to a preferred embodiment of the present invention: It can be determined by the smallest value of

1. Maximum available power of the transmitting D2D terminal (205 in FIG. 2) The transmission power which can set the reception power desired when the transmission D2D terminal (205 in FIG. 2) receives the signal transmitted by the transmission D2D terminal (205 in FIG. 2) 3. The transmission D2D terminal (FIG. 2) 2) such that when the base station (201 in FIG. 2) receives a signal transmitted by the base station (201 in FIG. 2), the base station does not cause a reception sensitivity reduction phenomenon in receiving signals received from other cellular terminals (203 in FIG. Transmission power

  The maximum available power of the terminal can also be the power physically available to the transmitter limited by the hardware of the terminal for transmitting information, or the maximum determined by any setting of the base station It can be power. Also, the reason for trying to align the receiving D2D terminal so that the receiving D2D terminal can receive the D2D channel transmitted by the transmitting D2D terminal to appropriate receiving power tries to facilitate scheduling for transmission of the transmitting D2D terminal It is. Assuming that the base station receives the D2D transmission transmitted by the transmission D2D terminal, the third variable maintains the reception power of the D2D transmission at a predetermined level or less than the signals received from other cellular terminals. The value does not increase beyond the value of. In this case, the third variable prevents a situation in which the received signal of the D2D terminal is much larger than the received signal of the cellular terminal at the base station to reduce the reception sensitivity of the signal of the cellular terminal. It is as follows when the said content is shown to numerical formula.

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

  In Equation (3), Tx_Power is the transmission power of the transmission D2D terminal, Max_Tx_Power is the maximum available 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 may be 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 transmitting D2D terminal when the Rx_Power_D2D is determined, and the function g (Rx_Power_eNB) is the transmitting D2D terminal when the Rx_Power_2NB is determined. It is the transmission power to be determined.

  Although the function f (Rx_Power_D2D) can be variously determined using the Rx_Power_D2D value, the most representative equation is as follows.

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

  In the equation (4), Prop_loss_D2D is a path loss due to the distance between the transmitting D2D terminal and the receiving D2D terminal, not only the distance between the transmitting and receiving units but also the state where the transmitting and receiving units are located, the existing medium between the transmitting and receiving units, etc. Determined by When the transmitting D2D terminal and the receiving D2D terminal set up the D2D channel, the transmitting D2D terminal sees path loss through transmission and reception of any promised signals and information sharing on the transmission power of said promised signals.

  The f (Rx_Power_D2D) equation can be defined using various variables other than the path loss value. The variable is an amount of resources of a channel to be transmitted (for example, the number of PRBs (Physical Resource Blocks) defined in LTE), or an arbitrary one set by a base station or set via a channel setting between D2D terminals. Offset values and various other variables can be mentioned by way of example. The f (Rx_Power_D2D) equation may be combined with giving any weight value to each variable. The weight may be changed, and may be set by a base station or may be set between D2D terminals through channel setting, and may correspond to a positive value or a negative value.

  The function g (Rx_Power_eNB) may be defined in various ways using Rx_Power_eNB values, but the most representative equation is as follows.

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

  In the equation (5), Prop_loss_eNB is the path loss due to the distance between the transmitting D2D terminal and the base station, and the state where the transmitting D2D terminal and the base station are located, as well as the distance between the transmitting D2D terminal and the base station, transmission D2D The transmission D2D terminal determines the reception power of the reference signal transmitted by the base station, which is determined by the existing medium between the terminal and the base station, and measures the transmission power of the reference signal from the base station to determine the transmission D2D. The path loss value of the terminal and the base station can be known.

  The desense offset (Desense_Offset) may be defined as a value that adjusts the base station not to reduce reception sensitivity when receiving both the D2D signal and signals from other cellular terminals. The desense offset (Desense_Offset) can be determined with an arbitrary value in consideration of the performance of the receiver of the base station, and can be set and notified to the transmitting D2D terminal by the base station.

  The g (Rx_Power_eNB) equation can be defined using various variables other than the path loss value. The variables may be, for example, the amount of D2D channel resources to be transmitted (eg, the number of PRBs (Physical Resource Blocks) defined in LTE), or any offset value set by the base station, and various other variables. Can. The g (Rx_Power_eNB) formula can adopt a scheme of giving an arbitrary weight value to each variable and combining them. The weight may be changed, may be set by the base station, and may correspond to a positive value or a negative value.

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

  FIG. 4 is a flowchart illustrating a process of controlling transmission power of a 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 step 404. Base station information may also be used in step 404. For example, a D2D transmitting / receiving terminal discovers each other (discovery), performs scheduling, and synchronization between each other should actually be to transmit data, the synchronization signal transmitted by the base station (PSS, SSS) etc. can be used.

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

  Although FIG. 4 shows that the base station that provides the power control related information to the transmitting D2D terminal 401 and the base station that provides the power control related information to the receiving D2D terminal 402 are the same base station 403, they are necessarily limited to this. Instead, for example, when the base stations to which each D2D terminal belongs are different base stations, they can 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 may also be predetermined at 404. The determination on the path loss may be shared between the transmitting D2D terminal 401 and the receiving D2D terminal 402 through path loss calculation and measurement reporting by measuring the reference signal in step 407 and in step 408. The transmission D2D terminal 401 can perform transmission of the D2D channel in step 409 using the following equation.

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

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

  The storage unit 501 stores the setting value related to power control received from the base station, that is, information used when determining f (Rx_Power_D2D), or 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 then the power control controller 502 determines the transmission power of the D2D channel using the above equation and transmits the power amplifier to the power amplifier through the control signal 503. Input the transmit power of D2D channel.

  Meanwhile, the D2D channel generator 504 generates a signal by which information transmitted via the D2D channel is wirelessly transmitted via channel coding, modulation and the like. The signal is amplified by a power amplifier 505. At this time, the power controller 502 uses the control signal 503 to determine the position to be amplified. The signal amplified by the power amplifier 505 is transmitted to the radio via the transmitting unit 506.

  Although the power controller 502 and the D2D channel generator 504 are separately divided into separate blocks in the above description, they are not necessarily divided into physically divided hardware as described above, and detailed functional blocks 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 apparatus for power control of a D2D terminal according to an embodiment of the present invention.

  The determination unit of the D2D power control related setting value of the base station determines a power control related setting value necessary when the D2D terminal receives the D2D channel (601). The power control related settings may include information used when determining f (Rx_Power_D2D). Further, the determination unit of the D2D power control related setting value of the base station determines a power control related setting value required when the base station receives the D2D channel (602). The power control related settings may include information used when determining g (Rx_Power_eNB).

  The two setting values are signaled to the D2D terminal via the transmitting unit 603. The signaled procedure is shown in step 405 of FIG. Although FIG. 6 shows the determination unit of the D2D power control related setting value divided into two blocks, it does not necessarily have to be divided into physically divided hardware as described above, and is performed by the control unit It should be noted that it can also be embodied in the detail function block.

Embodiment 2: When there is a D2D channel , in the second embodiment of the present invention described in the following power control of the cellular channel reception of the cellular terminal by D2D link reception of the D2D terminal located in the position where the base station is in contact The cellular terminal presents a new power control method to solve the desensitization problem.

  It has been described above that when the cellular terminal transmits information using the cellular channel in the reverse direction, the transmission power is used with a value determined by the following formula.

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

  In Equation (7), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum available 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 terminal when Rx_Power is determined is the transmission power determined thereby.

  In the present embodiment, the cellular terminal presents a method of setting the transmission power using another formula depending on whether or not the D2D terminal is present.

  That is, when there is a D2D terminal near the base station and the base station receives the transmission of the cellular terminal, the cellular terminal can be configured to receive the D2D terminal so that the reception sensitivity lowering problem is not generated by the D2D terminal. In some cases, an additional offset is added to the transmission power, and a method of transmitting with a stronger transmission signal is included. The embodiment described above can be expressed by the following equation.

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

  In Equation (8), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum available power of the terminal, Rx_Power is the reception power of the base station receiving the transmission signal of the terminal, and the function f (Rx_Power) is the above When Rx_Power is determined, the terminal can be the communication power determined thereby. Finally, a variable offset_D2D is an offset having another value depending on the presence or absence of a D2D terminal simultaneously transmitting with the cellular terminal when the cellular terminal transmits arbitrary data information or control information.

  Generally, a larger offset_D2D value can be set in the case where there are simultaneously transmitting D2D terminals than in the case where they do not. In one example, when there is a D2D terminal, it is possible to use offset_D2D (first offset) = 5 dB, and when there is no D2D terminal, offset_D2D (second offset) = 0 dB and so on.

  In addition, the effect of offset_D2D can be obtained by changing the setting of variables present in f (Rx_Power). The PUCCH f (Rx_Power) equation can be set as follows.

  here

  Are variables set for PUCCH performance in the upper layer, but one or more variables in this variable are divided into two sets and used in a general subframe in which D2D is not set. Set one set and another set to be used in subframes in which D2D is set. The terminal selects one of two variables or a set of variables set by determining whether D2D is present in a subframe currently transmitting PUCCH, and substitutes it into the above equation to use for PUCCH power setting. be able to.

    The offset_D2D value may be set by the base station via signaling, or may be determined with an arbitrary value. Alternatively, it can be added to the format of Downlink Control Information (DCI) set up conventionally, define a new DCI format, and notify the terminal of the offset_D2D value through the newly defined DCI format. For example, the offset_D2D value may be transmitted to the terminal through a Physical Downlink Control Channel. Alternatively, the information may be transmitted to the terminal using a field reserved in any of the conventionally defined DCI formats without defining a new DCI format, and any of the conventionally defined DCI formats may be transmitted. The offset_D2D value can also be sent to the terminal by defining the field to be interpreted differently.

  Meanwhile, the function f (Rx_Power) in Equation (9) can be determined by the method described above.

  Meanwhile, since it is known whether the cellular terminal is simultaneously transmitted by the D2D terminal, the base station may notify all subframes in which the D2D channel exists to all terminals belonging to the base station using system information. it can. Also, the base station can notify each terminal of the transmission time of the D2D terminal, and in this case, it can notify the terminal via higher layer signaling or physical layer control information.

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

  The cellular terminal starts operation in step 701 to obtain D2D transmission related information, for example, information on when and through which D2D transmission consists of D2D transmission, and offset_D2D information according to D2D transmission in step 702.

  The information on subframes in which the D2D transmission is performed may be used to determine which subframe A and B, which are offset_D2D information received by the terminal, are used.

  Also, regarding offset_D2D information by D2D transmission, if there is a D2D terminal, assuming that offset_D2D = A, and if there is no D2D terminal, assuming that offset_D2D = B, the value for (A, B) is the terminal Can be set in

  The D2D transmission related information may be obtained from system information through a broadcast channel, and may be set and notified by a base station for each terminal.

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

  The offset_D2D information is known via system information. Alternatively, the base station can notify offset_D2D information by terminal. In this case, upper 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 offset_D2D information, and the base station may transmit to the terminal through the PDCCH. Alternatively, the base station may transmit the information to the terminal using a field reserved in any format of the conventionally defined DCI format without defining a new DCI format. Also, the offset_D2D value may be transmitted to the terminal by defining the interpretation differently for any field of the conventionally defined DCI format.

  The cellular terminal then proceeds to step 703 to the cellular information, ie to the base station.

  In step 704, the D2D transmission related information obtained in step 702 is used to determine whether D2D transmission will be made together at the time of transmitting cellular information. For example, the terminal may determine whether a subframe for transmitting cellular information is a subframe for permitting D2D transmission.

  If it is determined that the D2D transmission is performed together, the UE proceeds to step 705 and sets offset_D2D = A, that is, an offset value necessary when D2D transmission is present. On the other hand, if D2D transmission is not achieved at the same time, the terminal proceeds to step 706 and sets offset_D2D = B, that is, an offset value necessary when D2D transmission does not exist.

  Then, the terminal determines transmission power using the offset_D2D value set in step 707 and the following equation.

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

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

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

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

  The terminal can obtain the D2D transmission related information from system information through a broadcast channel, and can be notified by the base station on a per-terminal basis. Similarly, the terminal can know offset_D2D from the system information or the base station can set and notify by terminal. As another embodiment, a new DCI format including the D2D transmission related information and offset_D2D information may be defined, and the base station may transmit to the terminal via PDCCH. Alternatively, the information may be transmitted to the terminal using a field reserved in any of the conventionally defined DCI formats without defining a new DCI format, and any of the conventionally defined DCI formats may be transmitted. The offset_D2D value can also be sent to the terminal by defining the interpretation to be different for the field of.

  The operation is finished in step 804.

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

  The judging device 901 judges whether D2D transmission exists or not. The power control related setting storage unit 902 stores the power control related setting received from the base station. When the information stored in the storage device 902 of the determination information of the D2D transmission permission determination unit 901 and the power control related setting value is input to the cellular transmission power controller 903, the transmission power for cellular information to be transmitted by this terminal is determined.

  The offset_D2D value is stored in the power control related setting value storage unit 902, and the cellular transmission power controller 903 determines an accurate offset_D2D according to the determination of the D2D transmission availability determination unit 901. The channel to which this terminal is to transmit is generated by the cellular channel generator 905 and amplified through the power amplifier 906, but the value to be amplified is the value determined by the cellular transmission power controller 903 to be input 904 to the power amplifier 906. It will be decided. The amplified cellular information is transmitted via the transmitting unit 907.

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

  FIG. 10 is a block diagram showing an internal structure of a 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 transmitter 1003.

  The following describes a method of multiplexing D2D information and cellular information presented in another embodiment of the present invention.

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

  In the following, it is assumed that transmission of D2D information or reception of cellular information is simultaneously performed by one terminal. The terminal may take a general cellular transmission to transmit reverse data information in the reverse direction (ie, at the base station) according to the scheduling of the base station and to transmit control information according to the forward data information in the reverse direction . However, there may be a case where transmission or reception for D2D information for D2D is required simultaneously with the cellular transmission.

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

  Another embodiment of the present invention, which will be described below, proposes a solution when transmission of cellular information and transmission and reception for D2D information occur simultaneously.

Embodiment 3: Simultaneous transmission of cellular channel and D2D channel In this embodiment, one terminal transmits reverse cellular information to the base station via the cellular channel, and simultaneously D2D information at the other D2D terminal via the D2D channel. Assume the situation to send. The terminal uses a single carrier frequency division multiple access (hereinafter referred to as SC-FDMA) transmission scheme.

  Therefore, it is assumed that the channel which one terminal transmits simultaneously is limited to one. If the terminal has to transmit the cellular and D2D channels simultaneously, the following operations are possible. Preferably, any one of the operations described later can be selected and performed.

1. Transmit only D2D channel.
2. Transmit only cellular channels.
3. Depending on the setting of the base station, one of the D2D channel and the cellular channel is selected to be transmitted. (In this case, the base station gives priority to the D2D channel and the cellular channel simultaneously when transmission and reception of the D2D channel and the cellular channel occur via system information, upper layer signaling such as RRC signaling or physical layer control information, etc. Information can be transmitted to the terminal.)
4. The two channels are simultaneously transmitted ignoring the SC-FDMA scheme. 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 this embodiment, one terminal transmits reverse cellular information including ACK / NACK at the base station via the cellular channel, and simultaneously transmits the D2D channel. Assume a situation in which D2D information is transmitted by other D2D terminals via the network.

  The fact that the terminal transmits information on ACK / NACK at the base station means that the base station notifies via the ACK / NACK whether or not the terminal is properly received with respect to forward information received in advance. It means that.

  If the information that the terminal transmits to the base station is ACK among ACKs / NACKs, that is, if the reception for the forward information becomes accurate, the ACK information is always transmitted to the base station, additional retransmissions are formed. Can be prevented. On the other hand, if the information transmitted from the base station by the terminal is NACK among the 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 reduced compared to the need to be done.

  Therefore, in the present embodiment, when one terminal transmits reverse cellular information including ACK / NACK at the base station via the cellular channel and simultaneously transmits D2D information at the other D2D terminal via the D2D channel, Considering the importance of ACK and NACK, when ACK / NACK information is ACK, D2D channel is not transmitted and only cellular channel is transmitted, and when ACK / NACK information is NACK, cellular channel is not transmitted and only D2D channel Suggest a plan to send

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

  If the operation of the terminal is started in step 1101 of FIG. 11, preparation for transmission of D2D information is performed in step 1102. Step 1103 prepares transmission for cellular information, if necessary. In this case, information to prepare for transmission in step 1103 may include information included in the PUCCH.

  Next, the UE determines in step 1104 whether transmission of uplink control information (PUCCH) is necessary, and transmits D2D information in step 1106 when PUCCH transmission is not necessary. If it is determined in step 1104 that PUCCH transmission is required, it is determined in 1105 whether ACK / NACK information included in the PUCCH is ACK or NACK.

  At this time, if the ACK / NACK information is ACK, the UE proceeds to step 1107 and transmits a PUCCH. Meanwhile, if the ACK / NACK information is NACK, the UE proceeds to step 1106 and transmits D2D information.

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

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

  Embodiment 5: Simultaneous selection of cellular channel transmission and D2D channel reception

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

  The terminal can not simultaneously transmit and receive via the same band. Therefore, according to the present invention, if the terminal has to simultaneously perform transmission of the cellular channel and reception of the D2D channel, the following operations are possible. Preferably, any one of the operations described later can be selected and performed.

1. Receive only D2D channel.
2. Transmit only cellular channels.
3. One of reception of D2D channel and transmission of cellular channel is selected according to the setting of the base station. (In this case, which operation should be prioritized between the transmission of the cellular channel and the reception of the D2D channel via the system information, upper layer signaling such as RRC signaling or control information of the physical layer, etc. Information can be transmitted to the terminal.)

  Embodiment 6: Selection for transmission of cellular control information and reception of D2D channel according to the type of cellular control information

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

  That the terminal transmits ACK / NACK information at the base station means that the terminal notifies the base station via ACK / NACK information on whether forward reception information received from the base station is properly received or not. It means that.

  If the information transmitted by the terminal at the base station is ACK among ACKs / NACKs, that is, if the reception for the forward information becomes accurate, the ACK information is always transmitted to the base station, additional retransmission will occur. Can be prevented. On the other hand, if the information transmitted from the base station by the terminal is NACK among the 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 will drop compared to the need to do so.

  Therefore, in the present embodiment, when one terminal transmits reverse cellular information including ACK / NACK at the base station via the cellular channel and simultaneously transmits D2D information at the other D2D terminal via the D2D channel, Considering the importance of ACK and NACK, when the ACK / NACK information is ACK, the D2D channel is not received and the cellular channel is transmitted. When the ACK / NACK information is NACK, the cellular channel is not transmitted and the D2D channel is received. Do.

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

  If operation of the terminal is started 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 operation 1203 may include information included in PUCCH. The UE determines in step 1204 whether PUCCH transmission is necessary. If it is determined that PUCCH transmission is not necessary, D2D information is received in step 1206.

  If it is determined in step 1204 that the PUCCH needs to be transmitted, it is determined in step 1205 whether the ACK / NACK information included in the PUCCH is an ACK. At this time, if the ACK / NACK information is ACK, the UE proceeds to step 1207 to transmit a PUCCH. Meanwhile, if the ACK / NACK information is NACK, the UE proceeds to step 1206 to receive D2D information.

  The step 1206 receives D2D information but does not transmit PUCCH information, and the step 1207 transmits PUCCH information but does not receive D2D information. Upon completion of operation 1206 or operation 1207, the operation of the terminal is completed in operation 1208.

  According to the embodiment of the present invention described above, it is possible to control the transmission power of the terminal that performs D2D communication to prevent the situation where the reception sensitivity reduction phenomenon occurs in the terminal that performs the existing cellular communication, to the maximum extent. 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 D2D communication.

  The embodiments of the present invention disclosed in the specification and the drawings are for the purpose of easily describing the technical contents of the present invention and presenting specific examples in order to facilitate understanding of the invention, thereby limiting the scope of the present invention. It does not mean. It is obvious to those skilled in the art to which the present invention belongs that other modifications based on the technical idea of the present invention can be implemented other than 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 possibility determination unit 902 storage device 903 cellular transmission power controller 904 input 905 cellular Channel generator 906 Power amplifier 907 Transmission unit 1001 Transmission time information generator 1002 Cellular transmission related information generator 1003 Transmission unit

Claims (12)

In a power control method in a communication system,
Confirming whether the first terminal's uplink transmission is at a first point in time;
And D. performing the sidelink transmission to the second terminal at the first time based on the transmission power when uplink transmission of the first terminal is not at the first time. . The power control method of claim 1, wherein the side link transmission includes at least one of a discovery signal, control information, and data information. The power control method according to claim 1, wherein the transmission power is a smaller value of the first transmission power and the second transmission power. The first terminal receiving power control related information from a base station;
The power control method of claim 3, wherein the first transmission power is determined based on the number of allocated resource blocks, path loss and the received power control related information. The power control method according to claim 3, wherein the second transmission power is a maximum transmission power for the side link transmission. The power control method according to claim 4, wherein the path loss is determined for a serving cell based on information provided by signaling of the base station. At the first terminal in the communication system:
A transceiver unit,
It is confirmed whether the uplink transmission of the first terminal is at a first point of time, and if the uplink transmission of the first terminal is not at the first point of time, to the second terminal at the first point of time based on transmission power. A control unit configured to control side link transmission; The terminal of claim 7, wherein the side link transmission includes at least one of a discovery signal, control information, and data information. The terminal according to claim 7, wherein the transmission power is a smaller value of the first transmission power and the second transmission power. The control unit
Further control to receive power control related information from the base station;
The terminal according to claim 9, wherein the first transmission power is determined based on the number of allocated resource blocks, a path loss and the received power control related information. The terminal according to claim 9, wherein the second transmission power is a maximum transmission power for the sidelink transmission. The terminal according to claim 10, wherein the path loss is calculated for a serving cell based on information provided by signaling of the base station.