KR20150128285A - Method and apparatus for reporting power headroom in wireless communicaton system supporting device to device communication - Google Patents

Abstract

Provided are a method and apparatus for reporting power headroom in a wireless communications system supporting device-to-device (D2D) communications. According to the present invention, the method for reporting, by a terminal, the power headroom in the wireless communications system supporting the D2D communications, comprises the following steps: triggering a power headroom report when a triggering condition is satisfied; calculating power headroom in a sub-frame capable of transmitting the power headroom report to configure the power headroom report; and transmitting the power headroom report to a device which allocates a resource for the D2D communications. The triggering condition can be determined with respect to which D2D transmission is activated or not, or a D2D resource pool.

Description

TECHNICAL FIELD [0001] The present invention relates to a surplus power reporting method and apparatus in a wireless communication system supporting inter-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a method and apparatus for reporting surplus power in a wireless communication system supporting device-to-device communication.

Proximity-based applications and services reflect emerging social-technology trends. Long term evolution (LTE) of the 3rd generation partnership project (3GPP) allows the provision of ProSe (Proximity Service) to meet the need for public safety. With the addition of discovery technology and broadcast communications to proximity-based services, technologies that provide compatibility with LTE standards are required. A representative of proximity-based application technology is device-to-device (D2D) communication. D2D communication is a communication method that has been available since the days of analog radios and has a very long history. However, the D2D communication in the wireless communication system is different from the existing inter-terminal communication.

D2D communication in a wireless communication system means communication in which data is directly exchanged between terminals without going through an infrastructure (for example, a base station) of a wireless communication system. That is, the two terminals perform communication by being a source and a destination of data, respectively. D2D communication provides advantages such as efficient use of limited radio resources, reduction of load of wireless communication system, and communication without network.

D2D communication may be performed using a communication method using a license-exempt band such as a wireless LAN or a Bluetooth, such as IEEE 802.11, but it is difficult to provide a planned and controlled service using the communication method using the license-exempt band. In particular, performance can be drastically reduced by interference. On the other hand, inter-terminal communication, which is operated or provided in a license band or inter-system interference controlled environment, can support quality of service (QoS), increase frequency utilization efficiency through frequency reuse, The distance can be increased.

In the inter-terminal communication in the licensed band, that is, in the inter-terminal communication based on the cellular communication, a method of allocating resources of a terminal corresponding to a cluster head (hereinafter referred to as a cluster head) . At this time, a cell uplink channel or uplink subframes may be used as resources to be allocated. D2D communication includes data communication between terminals and control signal communication between terminals.

The cluster head or the base station can utilize the power headroom information of the terminal to efficiently utilize the resources. Power control technology is a core technology for minimizing interference elements and reducing battery consumption of terminals in order to allocate resources efficiently in wireless communication. When a terminal provides redundant power information to a cluster head or a base station, the cluster head or the base station can estimate a time / frequency resource and an uplink maximum output power that can be allocated to the terminal. Accordingly, the cluster head or the base station can provide the UE with uplink scheduling such as transmission power control, modulation and coding level and bandwidth within a range not exceeding the estimated maximum power of the uplink.

SUMMARY OF THE INVENTION The present invention is directed to a surplus power reporting method and apparatus in a wireless communication system supporting inter-terminal communication.

Another aspect of the present invention is to provide a surplus power report triggering condition in a wireless communication system supporting inter-terminal communication.

It is another object of the present invention to provide a method and apparatus for calculating a surplus power report in a wireless communication system supporting inter-terminal communication.

According to an aspect of the present invention, a method for a terminal to report a power headroom in a wireless communication system supporting D2D (Device-to-Device) communication is a method in which, when a triggering condition is satisfied, Generating a power headroom report, calculating a surplus power in a subframe capable of transmitting the surplus power report to construct a surplus power report, and allocating a surplus power report to the resource for the inter- And the triggering condition may be determined based on whether to activate the D2D transmission or the D2D resource pool.

According to another aspect of the present invention, in a wireless communication system supporting inter-terminal communication, a method of transmitting resource allocation information by a device allocating resources for inter-terminal communication includes receiving a power headroom report from a terminal Determining a surplus power of the UE based on the surplus power report, performing uplink scheduling based on the surplus power, and allocating resource allocation information indicating a resource allocated by the uplink scheduling, Wherein the surplus power report comprises a device for allocating resources for inter-terminal communication and a device for allocating resources for inter-terminal communication separately from a surplus power report between the terminals, And an extra resource other than the surplus power report between the terminals.

According to another aspect of the present invention, in a wireless communication system supporting inter-terminal communication, a terminal reporting a power headroom may trigger a power headroom report when a triggering condition is satisfied, A processor for configuring a surplus power report by calculating a surplus power in a subframe capable of transmitting the surplus power report, a memory for storing the surplus power, and the surplus power report to a device for allocating resources for inter- , And the triggering condition may be determined based on whether the D2D transmission is activated or the D2D resource pool.

According to another aspect of the present invention, in a wireless communication system supporting inter-terminal communication, an apparatus for allocating resources for inter-terminal communication includes an RF (Radio Frequency) unit for receiving a surplus power report from the terminal, And a processor for performing uplink scheduling on the basis of the redundant power, wherein the RF unit includes a memory for storing resources allocated by the uplink scheduling, Wherein the surplus power report is received separately from the surplus power report between the device and the terminal, and transmits the surplus power report between the device and the terminal, Lt; / RTI >

According to the present invention, a cluster head or terminals existing in a service range of a base station can efficiently allocate resources for inter-terminal communication.

1 is a block diagram illustrating a wireless communication system to which the present invention is applied.
2 is a diagram for explaining the concept of a cellular network-based D2D communication applied to the present invention.
3 and 4 are views schematically showing the structure of a radio frame according to the present invention.
5 is a flowchart illustrating a PHR performing operation for D2D communication of a terminal according to an embodiment of the present invention.
6 and 7 are views showing an example of the structure of PHR MAC CE for D2D PHR applied to the present invention.
8 is a diagram showing an example of the structure of an extended PHR MAC CE for D2D PHR applied to the present invention.
9 is a diagram illustrating a MAC PDU structure for a D2D PHR applied to the present invention.
10 and 11 are views showing an example of a sub-header of a MAC PDU applied to the present invention.
12 is a flowchart showing a PHR receiving operation for D2D communication of a cluster head (or a base station) according to an embodiment of the present invention.
13 is a block diagram illustrating a terminal and a base station (or cluster head) performing D2D communication according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

In addition, the present invention will be described with respect to a wireless communication network. The work performed in the wireless communication network may be performed in a process of controlling a network and transmitting data by a system (e.g., a base station) Work can be done at a terminal connected to the network.

1 is a block diagram illustrating a wireless communication system to which the present invention is applied.

Referring to FIG. 1, a wireless communication system 10 is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system 10 includes at least one base station (BS). Each base station 11 provides communication services for a particular geographical area or frequency domain and may be referred to as a site. A site may be divided into a plurality of areas 15a, 15b, and 15c, which may be referred to as sectors, and the sectors may have different cell IDs.

A user equipment (UE) may be fixed or mobile and may be a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a digital assistant, a wireless modem, a handheld device, and the like. The base station 11 generally refers to a station that communicates with the terminal 12 and includes an evolved-NodeB (eNodeB), a base transceiver system (BTS), an access point, a femto base station (Femto eNodeB) (ENodeB), a relay, a remote radio head (RRH), and the like. The cells 15a, 15b and 15c should be interpreted in a comprehensive sense to indicate a partial area covered by the base station 11 and include all coverage areas such as megacell, macrocell, microcell, picocell, femtocell to be.

Hereinafter, a downlink refers to a communication or communication path from the base station 11 to the terminal 12, and an uplink refers to a communication or communication path from the terminal 12 to the base station 11 . In the downlink, the transmitter may be part of the base station 11, and the receiver may be part of the terminal 12. In the uplink, the transmitter may be part of the terminal 12, and the receiver may be part of the base station 11.

On the other hand, there is no limitation in the multiple access technique applied to the wireless communication system 10. [ (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA , OFDM-CDMA, and the like. These modulation techniques increase the capacity of the communication system by demodulating signals received from multiple users of the communication system. The uplink transmission and the downlink transmission may be performed using a time division duplex (TDD) scheme transmitted at different times or a frequency division duplex (FDD) scheme using different frequencies.

The layers of the radio interface protocol between the terminal and the base station are divided into a first layer (L1), a second layer (L1), and a second layer (L2) based on the lower three layers of an open system interconnection A second layer (L2), and a third layer (L3). Among them, the physical layer belonging to the first layer provides an information transfer service using a physical channel.

The physical layer is connected to a MAC layer (Media Access Control) layer through a transport channel. The data is transmitted between the MAC layer and the physical layer through a transmission channel. The transport channel is classified according to how the data is transmitted over the air interface. Further, data is transmitted through physical channels between different physical layers (i.e., between the physical layer of the terminal and the base station). The physical channel can be modulated by an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and uses time, frequency, and space generated by a plurality of antennas as radio resources.

For example, a physical downlink control channel (PDCCH) of a physical channel notifies a UE of resource allocation of a paging CHannel (DLH), a downlink shared channel (DL-SCH), and Hybrid Automatic Repeat Request (HARQ) And an uplink scheduling grant informing the UE of the resource allocation of the uplink transmission. The Physical Control Format Indicator CHannel (PCFICH) informs the UE of the number of OFDM symbols used for PDCCHs and is transmitted every subframe. Also, the PHICH (Physical Hybrid ARQ Indicator CHannel) carries HARQ ACK / NAK signals in response to the uplink transmission. Also, the Physical Uplink Control CHannel (PUCCH) carries uplink control information such as HARQ ACK / NAK, scheduling request and CQI for downlink transmission. Also, the Physical Uplink Shared CHannel (PUSCH) carries UL-SCH (Uplink Shared CHannel). If necessary, the PUSCH may include CSI (Channel State Information) information such as HARQ ACK / NACK and CQI according to the setup and request of the base station.

Hereinafter, the inter-terminal communication (D2D communication) will be described in detail. In recent years, research has been conducted to perform discovery and direct communication between devices in network coverage (in-coverage or out-of-coverage) for public safety and other purposes .

A terminal transmitting a signal based on inter-terminal communication may be referred to as a transmission terminal (Tx UE), and a terminal receiving a signal based on inter-terminal communication may be defined as a reception terminal (Rx UE). The transmitting terminal may transmit a discovery signal, and the receiving terminal may receive a discovery signal. The roles of the transmitting terminal and the receiving terminal may be changed. On the other hand, the signal transmitted by the transmitting terminal may be received by two or more receiving terminals.

2 is a diagram for explaining the concept of a cellular network-based D2D communication applied to the present invention.

D2D communication may mean a technique of directly transmitting and receiving data between terminals. Hereinafter, it is assumed that the terminal supports D2D communication in the embodiment of the present invention.

In a cellular system, the load of a base station can be dispersed when terminals at close distances perform D2D communication. In addition, when terminals perform D2D communication, the terminal transmits data at a relatively short distance, so that the transmission power consumption and latency of the terminal can be reduced. In addition, since the existing cellular-based communication and D2D communication use the same resources, the frequency utilization efficiency can be improved.

D2D communication can be classified into a communication method of a terminal located in network coverage (in-base coverage) and a communication method of a terminal located in an out-of-coverage area of network coverage (base station coverage).

2, communication between the first terminal 210 located in the first cell and the second terminal 220 located in the second cell, communication between the third terminal 230 located in the first cell and the third terminal located in the first cluster 210, 4 terminal 240 may be a D2D communication within the network coverage. The communication between the fourth terminal 240 located in the first cluster and the fifth terminal 250 located in the first cluster may be D2D communication outside the network coverage. Here, the fifth terminal 250 may operate as a cluster head (CH) of the first cluster.

D2D communication can be divided into a search procedure for performing discovery for communication between terminals and a direct communication procedure for transmitting and receiving control data and / or traffic data between terminals. D2D communication can be used for various purposes. For example, D2D communication within network coverage and D2D communication outside network coverage can be used for public safety. D2D communication outside network coverage may be used only for public safety.

As one embodiment of performing D2D communication, the base station 200 may transmit D2D resource allocation information to the first terminal 210. [ The first terminal 210 is a terminal located within the coverage of the base station 200. The D2D resource allocation information may include allocation information for a transmission resource and / or a reception resource that can be used for D2D communication between the first terminal 210 and another terminal (e.g., the second terminal 220) .

The first terminal 210 receiving the D2D resource allocation information from the base station can transmit the D2D resource allocation information to the second terminal 220. [ The second terminal 220 may be a terminal located outside the coverage of the base station 200. The first terminal 210 and the second terminal 220 can perform D2D communication based on the D2D resource allocation information. Specifically, the second terminal 220 can acquire information on the D2D communication resources of the first terminal 210. [ The second terminal 220 can receive data transmitted from the first terminal 210 through the resource indicated by the information on the D2D communication resource of the first terminal 210. [

In D2D communication, a terminal can transmit control data to another terminal. A separate channel (for example, a physical uplink control channel (PUCCH)) for transmitting control data in the D2D communication may not be defined. If the control channel is not defined in the D2D communication, the terminal can use various methods to transmit control data for D2D communication. In D2D communication, control data may also be expressed in terms of Scheduling Assignment (SA) information. Actual traffic data distinguished from control data in D2D communication can be expressed by the term D2D data.

D2D communication within network coverage may be represented by first mode communication, and D2D communication outside network coverage may be expressed by second mode communication. In the first mode communication, the base station or the relay node can schedule accurate information on resources for D2D communication of the terminal. Specifically, in the first mode communication, the base station can transmit resource allocation information on control data (or SA data) and resource allocation information on traffic data (or D2D data) to the terminal.

In a second mode of communication, a terminal (cluster head) can directly schedule resources for D2D communication based on a D2D resource pool. Specifically, in the second mode communication, resource allocation information for transmission of control data and resource allocation information for traffic data can be selected by the terminal from the D2D resource pool. D2D resource pools can be pre-configured or semi-statically allocated.

3 and 4 are views schematically showing the structure of a radio frame according to the present invention.

Referring first to FIG. 3, a radio frame includes 10 subframes. One subframe includes two slots. The time (length) for transmitting one subframe is called a transmission time interval (TTI). For example, the length of one subframe (1 subframe) may be 1 ms and the length of one slot (slot) may be 0.5 ms.

One slot may comprise a plurality of symbols in the time domain. For example, in a wireless system using OFDMA in a downlink (DL), the symbol may be an Orthogonal Frequency Division Multiplexing (OFDM) symbol, and in an uplink (UL) For a wireless system using Single Carrier-Frequency Division Multiple Access (FDMA), the symbol may be a Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol. On the other hand, the representation of the symbol period in the time domain is not limited by the multiple access scheme or name.

The number of symbols included in one slot may vary according to the length of a CP (Cyclic Prefix). For example, one slot may include seven symbols in the case of a normal CP, and one slot may include six symbols in the case of an extended CP.

Referring to FIG. 4, a resource block (RB) is a resource allocation unit, and may be a time-frequency resource corresponding to one slot on the time axis at 180 kHz as a frequency axis. A resource element (RE) is the smallest time-frequency resource to which a modulation symbol of a data channel or a modulation symbol of a control channel is mapped, and is a resource corresponding to one symbol in the time domain and one subcarrier in the frequency domain.

In a wireless communication system, it is necessary to estimate the state of an uplink channel or a downlink channel for data transmission / reception, system synchronization acquisition, channel information feedback, and the like. The terminal and / or the base station can perform channel estimation for recovering a transmission signal by compensating for distortion of a signal caused by a sudden change in the channel environment.

The terminal and the base station can use a reference signal (RS) for channel estimation between the terminal and the base station. In the case of downlink channel estimation, the UE knows the information of the reference signal received from the Node B. Accordingly, the UE estimates a channel based on the reference signal received from the Node B and compensates the channel value, thereby accurately obtaining downlink data transmitted from the Node B. In the case of the uplink channel estimation, the downlink channel estimation can be performed in the same manner as the downlink channel estimation, except that the transmitting entity of the reference signal is the terminal and the receiving entity is the base station.

The reference signal can generally be generated based on the reference signal sequence. The reference signal sequence may be one or more of several sequences having superior correlation characteristics. For example, a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence such as a Zadoff-Chu (ZC) sequence or a PN (pseudo-noise) sequence such as an m-sequence, a Gold sequence or a Kasami sequence May be used as a reference signal sequence, or various other sequences having superior correlation characteristics may be used depending on system conditions. Also, the reference signal sequence may be used by cyclic extension or truncation in order to adjust the length of the sequence, or may be used in various forms such as Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK) And may be mapped to a resource element.

In the downlink, a cell-specific RS (CRS), a MBSFN (Multimedia Broadcast and Multicast Single Frequency Network) reference signal, a UE-specific RS, a position reference signal PRS : Positioning RS, and CSI (Channel State Information) reference signal (CSI-RS).

The UE-specific reference signal is a reference signal received by a specific UE or a specific UE group in the cell. May be referred to as a downlink demodulation reference signal (DM-RS) since it is mainly used for demodulating downlink data for a specific terminal or a specific terminal group.

Similar to the downlink, the UE can transmit the uplink reference signal to the Node B on the uplink. The uplink reference signal may include uplink DM-RS and SRS. The uplink DM-RS may be used for coherent demodulation of the base station for uplink physical channels (PUSCH) and physical uplink control channel (PUCCH). Therefore, the uplink DM-RS may be allocated to the frequency bandwidth to which the PUSCH or PUCCH is allocated.

The uplink SRS can be used for channel estimation for channel dependent scheduling and link adaptation according to the uplink channel. When there is sufficient reciprocity between the uplink and downlink, that is, when the uplink and downlink channels have sufficiently similar characteristics, the uplink SRS can be used to estimate the downlink channel condition.

Hereinafter, the power headroom (PH) will be described.

The surplus power means an extra power that can be additionally used in addition to the power that the present terminal uses for uplink transmission. For example, assuming that the maximum transmission power, which is the uplink transmission power in the allowable range of the terminal, is 10W and the current terminal uses 9W of power in the frequency band of 10Mhz, in this case, the terminal can additionally use 1W, The power is 1W.

Here, if the base station allocates a frequency band of 20 MHz to the terminal, 18 W (= 9 W × 2) of power is required. However, since the maximum power of the UE is 10W, if the UE allocates 20Mhz, the UE can not use all of the frequency bands, or the UE can not properly receive signals of the UE due to insufficient power. In order to solve such a problem, the MS reports to the BS that the surplus power is 1 W, and allows the BS to perform scheduling within the surplus power range. This is called the Power Headroom Report (PHR).

(1) information on a difference between a maximum transmission power of a nominal terminal and an estimated UL-SCH (PUSCH) transmission power for each activated serving cell, 2) information on the difference between the maximum transmission power of the scheduled MS and the predicted PUCCH transmission power in the primary serving cell, or 3) the estimated maximum transmission power and the estimated UL-SCH and PUCCH transmission power in the main serving cell And the like can be transmitted.

The terminal's surplus power report can be defined as two types (first type and second type). The residue power of an arbitrary terminal may be defined for subframe i for serving cell c. The first type of redundant power report is performed when the UE transmits 1) only the PUSCH without the PUCCH, 2) simultaneously transmits the PUCCH and the PUSCH, and 3) the PUSCH is not transmitted. The second type of redundant power report is used when the UE transmits 1) PUCCH and PUSCH simultaneously to subframe i for the main serving cell, 2) transmits PUSCH without PUCCH, and 3) transmits PUCCH without PUSCH , And 4) does not transmit the PUCCH or PUSCH.

If an extended PHR (Extended PHR, hereinafter referred to as extended PHR) is not configured, only the first type of redundant power for the main serving cell is reported. On the other hand, if the extended surplus power report is configured, the first type of surplus power and the second type of surplus power are reported for each of the activated serving cells configured in the uplink.

The delay of the redundant power report refers to the difference between the starting point of the redundant power reference interval and the point at which the terminal starts transmitting the redundant power over the air interface. The delay of the surplus power report should be 0ms and the delay of the surplus power report may be applied for all the triggering schemes configured for the surplus power report.

The reported residual power is mapped to a specific index value, the embodiment of which is shown in the following table.

Reported value
(reported value) Measured quantitative values
(Measured quantity value, dB) POWER_HEADROOM_0 -23? PH <22 POWER_HEADROOM_1 -22? PH <-21 POWER_HEADROOM_2 -21? PH <20 POWER_HEADROOM_3 -20? PH <-19 POWER_HEADROOM_4 -19? PH <18 POWER_HEADROOM_5 -18? PH <-17 ... ... POWER_HEADROOM_57 34? PH <35 POWER_HEADROOM_58 35? PH <36 POWER_HEADROOM_59 36? PH <37 POWER_HEADROOM_60 37? PH <38 POWER_HEADROOM_61 38? PH <39 POWER_HEADROOM_62 39? PH <40 POWER_HEADROOM_63 PH = 40

Referring to Table 1, the surplus power falls within the range of -23 dB to +40 dB. If 6 bits are used to represent the residue power, it can represent 64 (= 26) kinds of indexes. Therefore, the surplus power can be divided into a total of 64 levels. For example, if the bit representing the redundant power is "0" ("000000" if represented by 6 bits), it indicates that the level of the surplus power is "-23? PPH <-22dB".

Hereinafter, a method of reporting information on the amount of transmission power available for each terminal to a network in a wireless communication system supporting D2D communication according to an embodiment of the present invention (hereinafter referred to as D2D PHR) ) Will be described. Hereinafter, a case where a resource used for communication between terminals is controlled by a network will be described by way of example, but the scope of the present invention is not limited thereto.

A terminal supporting D2D communication can perform D2D communication when a user of the terminal sets up the terminal to enable D2D communication through a user interface (UI). Or, a D2D server that manages a ProSe (Proximity Services) ID and a ProSe application ID of a terminal using D2D communication, a serving base station of the terminal, etc.) of a network (for example, It is possible to finally determine whether or not the D2D communication can be performed by the terminal set to be D2D communication. That is, the terminal may perform inter-terminal communication only when the inter-terminal communication of the terminal is permitted by the network even if the terminal is set to enable inter-terminal communication by the user of the terminal. Information on whether or not D2D communication is possible can be displayed on the screen of the terminal.

Meanwhile, resources for D2D communication can be allocated by a terminal (hereinafter referred to as a cluster head) or a base station that is responsible for allocating resources for D2D communication in D2D communication. Therefore, if the terminal performs D2D communication, the terminal must transmit the PHR to the base station within the network coverage, and transmit the PHR to the cluster head outside the network coverage. Hereinafter, the base station and the cluster head are collectively referred to as a base station for convenience of explanation.

The MCS (Modulation and Coding Scheme) level and the transmission power for the SA, the MCS level and the transmission power for the data transmission can be distinguished from each other. If the physical transmission scheme used for the SA is different from the physical transmission scheme used for the data transmission, the generated PH value may be required for both the SA and the data transmission. The D2D data reception is possible after the terminal receiving the D2D data first obtains the SA information provided by the terminal transmitting the data. Therefore, the SA and the data can not be transmitted at the same time. In addition, the MCS scheme for SA is fixed and the amount of frequency resource allocated for SA is always the same at the same time, and the MCS scheme to be set in D2D data transmission is determined by the cluster head (or base station) Or base station) and the time / frequency resource allocation for the data may be variable. For example, data transmission including single or multiple transmission blocks (TBs) through a single SA is possible.

FIG. 5 is a flowchart illustrating a PHR performing operation for D2D communication of a terminal according to an embodiment of the present invention, and FIGS. 6 and 7 illustrate an example of a structure of a PHR MAC CE for a D2D PHR applied to the present invention. FIG.

Referring to FIG. 5, if the D2D PHR triggering condition is satisfied, the terminal triggers the D2D PHR (S510).

As an example (Example 1-1), the D2D PHR may be triggered if it is predefined or the periodic D2D PHR timer configured by the base station (or cluster head) expires.

As another example (Embodiment 1-2), the D2D PHR can be triggered when D2D transmission (e.g., transmission of data or control signals) is started. At this time, the D2D PHR can be triggered on the basis of the enable of the D2D transmission. The activation includes a case where setting is completed in a state in which D2D communication is possible in units of a terminal, and a case in which a group capable of communicating in a D2D is set in a state in which D2D communication is enabled. The group may be established by a cluster header (or a base station) through an RRC reconfiguration procedure, and may be established through a discovery channel received by the terminal. This corresponds to the PHR being triggered when a secondary serving cell configured in the uplink is activated in the existing wireless communication system.

Alternatively, whether or not the D2D communication is enabled by the network is finally determined for the terminal for which the terminal user has made the D2D activation setting. According to the determination, the D2D PHR can be triggered at the time when the D2D transmission / reception of the terminal is finally possible. Also, the D2D PHR can be triggered even if a group capable of communicating with the D2D is set after the D2D transmission / reception of the terminal is finally set. For example, the network may be a D2D server that manages Proximity Services (ProSe) IDs and ProSe application IDs of all terminals using D2D communication, or a serving base station or a cluster head of the terminal. At this time, the D2D communication activation state can be displayed on the screen of the terminal.

Additionally, the D2D PHR may be triggered at a time when the terminal discovers a new D2D terminal (or group) through a D2D discovery signal or a D2D discovery channel and a new D2D data transfer to the D2D terminal (or group) is possible.

As another example (Embodiment 1-3), the D2D PHR is a signal having a signal intensity measured through a D2D synchronization signal (SS) or a discovery signal or a discovery channel, And may be triggered if it changes by more than a predetermined threshold configured by the base station (cluster head). That is, assuming that the transmission power to be set when transmitting the discovery signal or the discovery channel is fixed, the signal intensity measured through the signal or channel is determined by the path attenuation of the D2D radio channel between the target terminal transmitting the signal and the channel, . Thus, the D2D PHR may be triggered based on the amount of variation in path loss.

As another example (Embodiment 1-4), the D2D PHR can be triggered on the basis of the starting point of the D2D resource pool or a predetermined point in time before or after the D2D resource pool. The D2D resource pool may be a set of resources that can be used for D2D communication (hereinafter referred to as D2D communication candidate resource). Specifically, the D2D resource pool may be a collection of directed resources (D2D communication candidate resources) based on transmission opportunities. Here, the transmission opportunity may correspond to the D2D communication candidate resource. Multiple transmission opportunities can be defined within a D2D resource pool. For example, the transmission opportunity (or D2D communication candidate resource) may be discontinuously defined in at least one (e.g., one subframe or two) subframe units in successive subframes. Specifically, consecutive subframes can be divided into four subframe units. One preceding subframe in the divided four subframe units may be indicated as a transmission opportunity (or a D2D communication candidate resource).

The terminal calculates D2D surplus power (hereinafter referred to as D2D PH) when the D2D PHR is triggered (S520). At this time, the calculated D2D PH can be stored in the terminal.

In the conventional wireless communication system, the path attenuation amount is calculated using the CRS as a reference signal when calculating the PH. However, in calculating the D2D PH, the terminal uses the D2D synchronization signal, the discovery signal, or the discovery channel as a reference signal Path attenuation can be calculated. Further, when calculating the D2D PH, the upper layer determination parameter may or may not use a predetermined default value (i.e., a value of 0 or 1 can be used).

As an example (Embodiment 2-1), the terminal can calculate D2D PH in the subframe for the most recent D2D data transmission. In this case, the calculation of D2D PH may be performed in the subframe where the data transmission is performed. That is, the D2D PH can be calculated only in a section where a resource pool capable of D2D data transmission exists. At this time, the terminal can discard the stored PH value when a predetermined time (for example, a PHR cycle timer value) elapses.

In addition, when the UE receives a grant for uplink transmission of a wide area network (WAN), i.e., a wireless cellular communication, the UE can transmit the generated PH information to the base station (or the cluster header). Here, the PH information includes a real PH value and time information of a subframe in which the actual PH value is generated. Here, the time information may be a value obtained by converting an actual time (for example, minute / second unit) into 8 bits in the form of a time stamp, or a value obtained by converting a subframe in which a PHR is transmitted in a frame / May be a value obtained by converting the state time to 8 bits. If the extended D2D PHR MAC CE is used, a field including broadcast and a PH field for each group and time stamp information for each group PH information may be included.

On the other hand, when the UE receives a grant for uplink transmission of wireless cellular communication from a base station (or a cluster head) at a time point of overlapping with a resource pool period in which D2D data transmission is possible, the UE calculates D2D PH . At this time, the terminal computes a virtual PH value as D2D PH. This is because uplink transmission of wireless communication data and D2D data transmission can not occur at the same time. The virtual format used to generate the virtual PH value may be a data transmission format that is set to the lowest MCS value and the minimum frequency resource amount in a format known in advance by the cluster header (or the base station) and the terminal, but is not limited thereto. If using extended D2D PHR MAC CE, the 'V' field is not used and is reserved. Here, the 'V' field indicates whether the reported residual power is based on the actual transmission or based on the reference format. In this manner, the terminal transmits the virtual PH value, so that the base station (or the cluster head) can confirm the path attenuation amount of the D2D communication link considered by the corresponding terminal.

As another example (Embodiment 2-3), when a terminal receives a grant for uplink transmission of wireless cellular communication from a base station (or a cluster head) overlaps with a resource pool period in which D2D data transmission is possible, D2D PH But it can be transmitted with the actual PH value. If there is a scheduled D2D data transmission in the current D2D resource pool, the terminal can calculate (estimate) the actual PH value assuming that the transmission of the scheduled D2D data is to be transmitted in the subframe in which the D2D PHR is to be transmitted. At this time, the terminal can assume that there is no transmission power to be allocated for uplink transmission of wireless communication data.

Thus, the base station (or the cluster head) can know the information for D2D data transmission in advance and can utilize it in the future D2D scheduling by predicting the actual PH value on the assumption of the D2D data transmission.

On the other hand, when the D2D PH is calculated, the terminal configures at least one PHR MAC CE (hereinafter referred to as "D2D PHR MAC CE") for transmitting the D2D PHR based on the calculated D2D PH (S530). At this time, the D2D PHR MAC CE may be an extended PHR MAC CE. Also, the D2D PHR may include classification information for a D2D communication object (group / broadcast, etc.). For example, if the D2D PHR is not an extended PHR MAC CE, a PH field consisting of one octet may be configured. For example, the D2D PHR MAC CE may be configured as shown in FIG.

Referring to FIG. 6, the PH field is composed of 6 bits and has the same category as a conventional wireless communication system. In the wireless communication system, the two bits which have been set as the spare bits can indicate the division information for the D2D communication object (group / broadcast, etc.). For example, '00' indicates PH in case of a broadcast type, and '01' through '11' indicates a group index indicated by an upper layer (for example, RRC) May be directed to an object.

Meanwhile, the D2D PHR MAC CE may be composed of a plurality of octets as shown in FIG.

Referring to FIG. 7, the D2D PHR may include PH information on broadcast type D2D transmission and information on all groups. The PH information included in the first octet is in a broadcast form, and the PH information corresponding to the group index indicated by the upper layer (for example, RRC) among the groups is included in ascending order from the PH information included in the second octet. In this case, the 'V' field used in the existing wireless communication system may be defined for this, because it may include a case where D2D transmission can not actually occur in a specific group.

Then, the terminal transmits the constructed D2D PHR MAC CE to the base station (or cluster head) (S540). At this time, the D2D PHR can be transmitted separately from the PHR for uplink transmission of wireless communication data. Here, the D2D PHR MAC CE may be set to extend regardless of the setting of the PHR MAC CE for wireless cellular communication, and whether the PHR MAC CE is established for wireless cellular communication may be directly applied to the D2D PHR MAC CE extension have.

If a PHR for uplink transmission of wireless communication data is triggered, the terminal preferentially transmits PHR for uplink transmission of the wireless communication data. At this time, the terminal can transmit D2D PHR only when a PHR for uplink transmission of the wireless communication data is available and there is a resource to transmit D2D PHR.

8 is a diagram showing an example of the structure of an extended PHR MAC CE for D2D PHR applied to the present invention.

Referring to FIG. 8, the extended PHR MAC CE includes a plurality of octets. The first octet is a field for indicating whether PH information is included in the D2D communication object corresponding to each of C1 to C7. Each of C1 to C7 represents a communication object (group / broadcast). For example, when C1 to C7 are set to '1', it is assumed that D2D transmission is performed on a target corresponding to the group index indicated by an upper layer (for example, RRC) among the groups, or PH information generated upon D2D transmission . The second octet consists of a 'P' field, a 'V' field and a field indicating the redundant power (PH) for the scheduling assignment (SA) channel. That is, it represents the PH value for the SA channel used when the UE transmits the SA information in broadcast type D2D transmission, which is always included in the extended D2D PHR MAC CE configuration. Here, the 'P' field indicates whether or not the UE has applied a power backoff by power management. The 'V' field is an indicator indicating whether the reported residual power is based on the actual transmission or based on the reference format. In the case of the surplus power of the D2D data transmission channel, when V = 0, it indicates that there is PUSCH transmission for actual D2D data transmission, and when V = 1, it indicates that PUSCH reference format for D2D data transmission is used. In the case of the surplus power of the SA channel, when V = 0, it indicates that there is PUSCH transmission for actual D2D SA transmission, and V = 1 indicates that PUSCH reference format for D2D SA transmission is used.

On the other hand, the third octet includes a 'P' field, a 'V' field, and a field indicating an extra power (PH) related to the D2D data channel. The fourth octet consists of a P field, a V field, and a field indicating the residue power (PH) of the D2D data channel for the first group (Group 1). The residue power for the group 1 may consider both the SA and the data channel, and may consider only the data channel.

FIG. 9 is a diagram illustrating a MAC PDU structure of a wireless cellular communication system for transmitting a D2D PHR applied to the present embodiment, and FIGS. 10 and 11 are views showing an example of a MAC subheader. The MAC PDU may be referred to as a transport block.

Referring to FIG. 7, a PHR MAC CE for D2D PHR may be included in MAC PDU 900. The MAC PDU 900 includes a MAC header 910, at least one MAC control element CE 920-1, ..., 920-n, at least one MAC SDU , 930-1, ..., 930-m, and padding 940.

The MAC control elements 920-1, ..., 920-n are control messages generated by the MAC layer. The MAC header 910 includes at least one sub-header 910-1, 910-2, 910-3, 910-4, ..., 910-k, and each sub-header 910- 1, 910-2, 910-3, 910-4, ..., 910-k correspond to one MAC SDU or one MAC control element or padding 940. The order of the subheaders 910-1, 910-2, 910-3, 910-4, ..., 910-k is the same as the order of the corresponding MAC SDUs 930-1, ..., 930- -m), the MAC control elements 920-1, ..., 920-n, or the padding 940.

Each of the subheaders 910-1, 910-2, 910-3, 910-4, ..., 910-k includes four fields such as R, R, E and LCID, , LCID, F, L, and so on. The subheader including the four fields is a subheader corresponding to the MAC control elements 920-1, ..., 920-n or the padding 940. The subheader including the six fields includes a MAC SDU 930 -1, ..., 930-m.

10 illustrates a structure of a MAC subheader including six fields R, R, E, LCID, F and L, and four fields R, R, E and LCID in FIG. The structure of the MAC subheader including the MAC header is shown. Hereinafter, the fields included in the MAC subheader will be described in more detail.

The logical channel ID (LCID) field is a field for identifying a logical channel of a corresponding MAC SDU or identifying a type of a corresponding MAC control element or padding. The length (size) of the LCID field is 5 bits. The LCID field is one MAC SDU included in the MAC PDU, one MAC control element, or one per padding.

For example, the LCID field for the uplink may be determined by the MAC control elements 920-1, ..., 920-n as the MAC CE for the D2D PHR, the MAC CE for the PHR in the wireless communication Or extended PHR MAC CE). That is, the LCID field may include identification information indicating that it is a D2D PHR.

index LCID value 00000 CCCH 00001-01010 Logical channel identification 01011-10110 Reserved 10111 Extended D2D PHR 11000 D2D PHR 11001 Extended PHR 11010 PHR 11011 C-RNTI 11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 padding

The Length field is a field for identifying the length of the corresponding MAC SDU or the length of a variable-sized MAC control element. The length of the 'L' field is set to a format (F: Format) field. &Lt; / RTI &gt; In Fig. 10, for example, the length of the 'L' field is 7 bits and the case of 15 bits is a sub-header.

The 'F' field is a field for identifying the length of the 'L' field, and may have a length of 1 bit. If the length of the MAC SDU or variable size MAC control element is less than 128 bytes, the value of the 'F' field may be set to '0', otherwise it may be set to '1'.

The Extension (E) field is a flag that identifies whether other fields are present in the MAC header. When set to "1", there is at least another set of R / R / E / LCID fields. Indicates that the MAC SDU, MAC control element or padding is started in the next byte when set to "0 ".

The R (Reserved) field is a reserved field and is set to "0 ".

12 is a flowchart showing a PHR receiving operation for D2D communication of a cluster head (or a base station) according to an embodiment of the present invention. The reception of the D2D PHR may be performed by the cluster head or by the base station.

Referring to FIG. 12, the cluster head (or base station) receives the D2D PHR from the terminal (S1210). For the D2D PHR, for example, a D2D PHR MAC CE as shown in FIG. 6 or 7 may be used and an extended PHR MAC CE for the D2D PHR as shown in FIG. 8 may be used. The PHR MAC CE and the extended PHR MAC CE for the D2D PHR may be included in a MAC PDU as shown in FIG. 9 and received by the base station. At this time, the D2D PHR can be received separately from the PHR for uplink transmission of wireless communication data.

Meanwhile, the cluster head (or the base station) can receive the D2D PH calculated by the UE together with the uplink transmission of the wireless cellular communication. In this case, the received information may be the actual PH value and the time information of the subframe in which the actual PH value is generated, and the time information of the subframe in which the actual PH value is generated may be a real time (e.g., Min) / 8), or a value obtained by converting the relative time value of the system frame / subframe into 8 bits based on the subframe in which the D2D PHR is transmitted.

Upon receiving the D2D PHR MAC CE, the cluster head (or the base station) confirms the surplus power based on the D2D PHR MAC CE (S1220). For example, the cluster head (or the base station) may check the group power of the group based on the group index field of the D2D PHR MAC CE and determine from the PH field about the group included in the PHR MAC CE Can be confirmed. Then, the cluster head (or the base station) performs uplink scheduling based on the information confirmed through the D2D PHR (S1230). Here, the uplink scheduling includes determining a D2D SA to be allocated to each UE and all radio resources that can be determined by the cluster head (or the base station) for data transmission. Then, the cluster head (or the base station) transmits D2D resource allocation information indicating a resource allocated by the scheduling to the terminal (S1240). Here, the D2D resource allocation information may be included in downlink control information (DCI).

On the other hand, when the SA and the physical transmission scheme used for data transmission are the same and resources not distinguished from each other are used, the mobile station can handle the SA and the PH for data transmission without distinguishing them. In this case, the period in which the UE can generate and transmit the D2D PHR is extended to the entire D2D resource pool.

13 is a block diagram illustrating a terminal performing a D2D communication and a cluster head (or a base station) according to an embodiment of the present invention. 13, the terminal 1300 includes a processor 1305, an RF unit 1310, and a memory 1315.

The terminal 1300 includes a processor 1305, an RF unit (radio frequency unit) 1310, and a memory 1315. The memory 1315 is connected to the processor 1305 and stores various information for driving the processor 1305. [ The RF unit 1310 is connected to the processor 1305 to transmit and / or receive a radio signal. For example, RF section 1310 may transmit the D2D PHR MAC CE published herein to base station or cluster head 1350 and may receive resource allocation information from base station or cluster head 1350.

The processor 1305 triggers the D2D PHR when the D2D PHR triggering condition is met. An embodiment of the D2D PHR triggering condition is as follows.

In one example, if the predefined or periodic D2D PHR timer configured by the cluster head (or base station) expires, the processor 1305 triggers the D2D PHR.

In another example, if D2D transmission (e.g., transmission of data or control signals) is possible, processor 1305 triggers D2D PHR. In this case, the processor 1305 can trigger the D2D PHR based on the enablement of the D2D transmission. Here, whether or not the terminal can enable D2D can be set by the terminal user (e.g., switch ON / OFF by UI operation). Alternatively, the processor 1305 may trigger the D2D PHR at a time when the D2D transmission / reception of the terminal is finally possible according to the determination of the network. At this time, the D2D communication activation state can be displayed on the screen of the terminal. For example, the terminal can be activated when D2D communication is enabled, when the setting is completed, or when a group capable of communicating with the D2D is set in a state where D2D communication is enabled. The group may be established by a cluster header (or a base station) through an RRC reconfiguration procedure, or may be established through a discovery channel received by the terminal.

If the terminal finds a new D2D terminal (or group) on the D2D discovery channel and is able to transmit new D2D data to the D2D terminal (or group), the processor 1305 determines whether the new D2D terminal (or group) The D2D PHR can be triggered at a time when D2D data transmission is possible.

As another example, if the signal strength measured via the D2D sync signal or the D2D discovery signal (or D2D discovery channel) is changed beyond a predetermined threshold configured by the cluster head (or base station) Lt; / RTI &gt; can trigger the D2D PHR. Alternatively, the processor 1305 may trigger the D2D PHR based on path loss variation.

As another example, the processor 1305 may trigger the D2D PHR based on a start point of time of the D2D resource pool, or a predetermined point in time before / after the start of the D2D resource pool.

On the other hand, the processor 1305 calculates the D2D surplus power. The calculation of the D2D residue power may be performed before the triggering of the D2D PHR, or may be performed simultaneously with the triggering of the D2D PHR. At this time, the calculated D2D PH may be stored in the memory 1315. The D2D PH stored in the memory 1315 may be provided to the processor 1305 according to the request of the processor 1305. [

The processor 1305 may calculate the path attenuation to the reference signal as a discovery signal or a discovery channel in calculating the D2D PH. Further, when calculating D2D PH, the processor 1305 may or may not use a default value as the upper layer determination parameter (i.e., a value of 0 or 1 may be used).

In one example, processor 1305 may calculate D2D PH in the subframe for the most recent D2D data transmission. The D2D PH calculation may be performed in a subframe in which data transmission is performed, which may be a part or all of a period in which a resource pool capable of D2D data transmission exists. If the PH value stored in the memory 1315 exceeds a predetermined time (for example, a PHR cycle timer value), the processor 1305 can discard it from the memory 1315. [

As another example, the processor 1305 may determine that a point in time when a grant for a wide area network (WAN), i.e., a wireless cellular communication uplink transmission, from a cluster head (or a base station) is overlapped with a resource pool period in which D2D data transmission is possible D2D PH calculations can be performed. At this time, the processor 1305 calculates the virtual PH value as D2D PH. The virtual format used to generate the virtual PH value may be a data transmission format set to the lowest MCS value.

As another example, the processor 1305 may calculate the D2D PH when the point of time when the grant for the wireless cellular communication uplink transmission from the cluster head (or the base station) is overlapped with the D2D data transmission enabled resource pool period, Can be calculated.

In addition, processor 1305 may calculate the actual PH value assuming that the scheduled D2D data transmission is to be transmitted in the subframe in which the D2D PHR is to be transmitted, if there is a scheduled D2D data transmission in the current resource pool. At this time, the terminal can assume that there is no transmission power to be allocated for uplink transmission of the non-communication data.

On the other hand, the processor 1305 may configure at least one PHR MAC CE for the D2D PHR based on the computed D2D PH. At this time, at least one D2D PHR MAC CE configured may be an extended PHR MAC CE as shown in FIG. At this time, the LCID field for the uplink can identify whether the MAC control element is the MAC CE for the D2D PHR and the MAC CE for the PHR (or the extended PHR MAC CE) for the wireless communication data as shown in Table 2 .

Meanwhile, the RF unit 1310 transmits the D2D PHR MAC CE to the RF unit 1355 of the base station or the cluster head. At this time, the D2D PHR can be transmitted separately from the PHR for the wireless communication data.

If a PHR for uplink transmission of wireless communication data is triggered, the RF unit 1310 preferentially transmits PHR for uplink transmission of the wireless communication data. At this time, the RF unit 1300 can transmit a PHR for uplink transmission of the wireless communication data and transmit D2D PHR only when there is a resource to transmit the D2D PHR.

In another example, when the RF unit 1310 receives a grant for wireless cellular communication uplink transmission, the D2D PH calculated by the processor 1305 is transmitted to the RF unit 1355 of the base station or the cluster head together with the wireless cellular communication uplink transmission ).

At this time, the transmitted information may include the actual PH value and the time information of the subframe in which the actual PH value is generated. In this case, the time information of the subframe in which the actual PH value is generated may be a value obtained by converting the form of real time (for example, minute / second unit) into 8 bits in the form of a time stamp, / The relative time value of the subframe may be converted into 8 bits.

On the other hand, the base station or cluster head 1350 includes an RF section 1355, a processor 1360, and a memory 1365. The memory 1365 is coupled to the processor 1360 and stores various information for driving the processor 1360. RF section 1355 is coupled to processor 1360 to transmit and / or receive wireless signals.

The RF unit 1355 receives the D2D PHR from the RF unit 1310 of the terminal 1300. For example, the RF unit 1355 can receive the D2D PHR in a manner different from the PHR for the wireless communication data. The memory 1365 can store the PHR received by the RF unit 1355.

As another example, the RF unit 1355 may receive the D2D PH computed by the terminal 1300 along with the wireless cellular communication uplink transmission. The received information may include an actual PH value and time information of a subframe in which the actual PH value is generated. The time information of the subframe in which the actual PH value is generated may include a real time (e.g., Min) / 8), or a value obtained by converting the relative time value of the system frame / subframe into 8 bits based on the subframe in which the D2D PHR is transmitted.

Meanwhile, the processor 1360 confirms surplus power based on the D2D PHR. For example, the processor 1360 may determine whether the redundant power for a D2D group is reported based on the group index field of the D2D PHR MAC CE, and determine from the PH field about the serving cell included in the PHR MAC CE Can be confirmed. The processor 1360 also performs uplink scheduling based on the D2D PHR. Here, the UL scheduling includes determining resources to be allocated to each UE.

The processor 1360 transmits resource allocation information indicating the D2D resource allocated by the UL scheduling to the RF unit 1315. [ Here, the resource allocation information may be included in downlink control information (DCI).

The processor may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The RF unit may include a baseband circuit for processing the radio signal. When the embodiment according to the present invention is implemented in software, the above-described technique may be implemented by a module (process, function, etc.) that performs the above-described function. The module is stored in memory and can be executed by the processor. The memory may be internal or external to the processor and may be coupled to the processor by any of a variety of well known means.

In the above-described exemplary system, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders . It will also be understood by those skilled in the art that the steps shown in the flowchart are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention.

Claims (20)

A method for a terminal to report a power headroom in a wireless communication system supporting D2D (Device-to-Device) communication,
Triggering a power headroom report if the triggering condition is satisfied;
Constructing a surplus power report by calculating a surplus power in a subframe capable of transmitting the surplus power report; And
Transmitting the surplus power report to an apparatus for allocating resources for inter-terminal communication
Lt; / RTI &gt;
The triggering condition includes:
Wherein the determination is made based on whether the D2D transmission is activated or the D2D resource pool. The method according to claim 1,
Whether or not the D2D transmission is activated,
Wherein the power control information is set in a user interface of the terminal. The method according to claim 1,
Whether or not the D2D transmission is activated,
Wherein the triggering condition is finally determined by an apparatus for allocating resources for inter-terminal communication, and the Triggering condition is satisfied at a time when D2D transmission / reception of the terminal is possible according to the determination. The method according to claim 1,
The triggering condition includes:
Wherein when the UE finds a new D2D terminal or group on the D2D discovery channel and attempts to start a new D2D data transmission, the terminal is satisfied at the time of starting the new D2D data transmission. The method according to claim 1,
The triggering condition includes:
Wherein the signal strength measured through the D2D synchronization signal, the D2D discovery signal or the D2D discovery channel is satisfied when the intensity is changed by a predetermined threshold or more, Power reporting method. The method according to claim 1,
The surplus electric power,
Frame is calculated in a subframe for D2D data transmission that is most recently performed. The method according to claim 6,
The sub-
Wherein the subframe is a subframe in which D2D data transmission is performed, and is a part or all of a section in which a resource pool capable of D2D data transmission exists. The method according to claim 1,
Wherein the calculating the surplus power comprises:
And a step of calculating a virtual surplus power when a time point at which a grant for uplink transmission is received from a device for allocating resources for inter-terminal communication overlaps with a resource pool period in which D2D data transmission is possible. Reporting method. The method according to claim 1,
Wherein the calculating the surplus power comprises:
Calculating a real surplus power when a point of time when a grant for uplink transmission is received from an apparatus for allocating resources for inter-terminal communication overlaps with a resource pool period in which D2D data transmission is possible; And
And calculating the actual residue power assuming that the scheduled D2D data transmission is to be transmitted in the subframe in which the redundant power report is to be transmitted if there is a scheduled D2D data transmission in the resource pool. Reporting method. A method of transmitting resource allocation information by a device allocating resources for inter-terminal communication in a wireless communication system supporting D2D (Device-to-Device) communication,
Receiving a power headroom report from the terminal;
Confirming surplus power of the terminal based on the surplus power report;
Performing uplink scheduling based on the surplus power; And
Transmitting resource allocation information indicating a resource allocated by the UL scheduling to the UE;
Lt; / RTI &gt;
The surplus power report includes:
A device for allocating resources for inter-terminal communication, an apparatus for allocating resources for inter-terminal communication, separately received from an idle power report between the terminals, and an apparatus for allocating resources for inter- &Lt; / RTI &gt; 1. A terminal reporting a power headroom in a wireless communication system supporting D2D (Device-to-Device) communication,
A processor for triggering a power headroom report if a triggering condition is satisfied and for configuring a surplus power report by calculating a residue power in a subframe capable of transmitting the redundant power report;
A memory for storing the surplus power; And
An RF (Radio Frequency) unit for transmitting the surplus power report to an apparatus for allocating resources for inter-
/ RTI &gt;
The triggering condition includes:
And whether the D2D transmission is activated or not is determined based on a D2D resource pool. 12. The method of claim 11,
Whether or not the D2D transmission is activated,
Wherein the terminal is set in a user interface of the terminal. 12. The method of claim 11,
Whether or not the D2D transmission is activated,
Wherein the triggering condition is satisfied when the D2D transmission / reception of the terminal is possible according to the determination. 12. The method of claim 11,
The triggering condition includes:
Wherein when the new D2D terminal or group is discovered through the D2D discovery channel and a new D2D data transmission is to be started, the terminal is satisfied at the start of the new D2D data transmission. 12. The method of claim 11,
The triggering condition includes:
A signal strength measured through a D2D synchronization signal, a D2D discovery signal, or a D2D discovery channel is predefined or is changed by a predetermined threshold or more, which is configured by a device allocating resources for the inter-terminal communication. . 12. The method of claim 11,
The processor comprising:
And calculates a surplus power in a subframe for D2D data transmission that is most recently performed. 17. The method of claim 16,
The sub-
A subframe in which D2D data transmission is performed, and is a part or all of a section in which a resource pool capable of D2D data transmission exists. 12. The method of claim 11,
The processor comprising:
And calculates a virtual surplus power when a time point at which a grant for uplink transmission is received from a resource allocating apparatus for inter-terminal communication overlaps with a resource pool period in which D2D data transmission is possible. 12. The method of claim 11,
The processor comprising:
When a point of time when a grant for uplink transmission is received from a resource allocating apparatus for inter-terminal communication overlaps with a resource pool period in which D2D data transmission is possible,
And calculates the actual surplus power assuming that the scheduled D2D data transmission is to be transmitted in a subframe in which the surplus power report is to be transmitted if there is a scheduled D2D data transmission in the resource pool. An apparatus for allocating resources for inter-terminal communication in a wireless communication system supporting device-to-device (D2D) communication, the apparatus comprising:
An RF (Radio Frequency) unit for receiving a surplus power report from the terminal;
A memory for storing the surplus power report; And
A processor for performing uplink scheduling on the basis of the surplus power, checking the surplus power of the terminal based on the surplus power report,
Lt; / RTI &gt;
The RF unit includes:
Transmitting resource allocation information indicating a resource allocated by the uplink scheduling to the UE,
The surplus power report includes:
And is received separately from an excess power report between the device and the terminal, and is received through an extra resource other than a surplus power report between the device and the terminal.

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