KR20160134438A - Method for operating relay device in wireless communication system and device using the method - Google Patents

Abstract

A method and apparatus for operating a relay terminal in a wireless communication system supporting inter-terminal communication are provided. A method of operating a buffer state report (BSR) by a terminal in a wireless communication system supporting D2D (Device to Device) communication is a method in which a first terminal located in a network coverage receives a network coverage Receiving data to be delivered to a second terminal located outside the first terminal, and triggering a BSR for data excluding data to be transmitted to the second terminal among data to be transmitted through D2D communication existing in a buffer in the first terminal Configuring a Media Access Control (MAC) control element for the triggered BSR, and transmitting a MAC control element for the constructed BSR to the BS.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for operating a relay terminal in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to wireless communication, and more particularly, to a wireless communication system supporting device-to-device communication in which, when resources used for communication between terminals are controlled by a network, And more particularly, to a method and apparatus for operating a relay terminal that relays communication between a terminal and a base station located outside of the relay terminal.

Device to Device (D2D) communication is a communication method that has been available since the days of analog radios, and has a long history. However, D2D communication in a wireless communication system is different from existing D2D communication. D2D communication in a wireless communication system is a method in which terminals geographically close to each other use transmission and reception techniques of the wireless communication system in a frequency band of a wireless communication system or other frequency bands but directly transmit and receive data without going through an infrastructure such as a base station Communication. This provides the advantage that the terminal can use the wireless communication in an area other than the area where the wireless communication infrastructure is constructed and reduce the network load of the wireless communication system.

In such a wireless communication system, a base station may schedule resources required for in-coverage of a terminal to perform D2D communication. In this case, the terminal may transmit D2D communication to a buffer in the terminal. The buffer status report (BSR) to inform the base station how much data is available for the BS. At this time, a method of operating the BSR is not yet defined in the case where the UE performs a role of a relay terminal that transmits data received from the BS to a UE that is not in a coverage area for the purpose of coverage expansion, that is, expansion of a service range. Therefore, a concrete method for operating the BSR is required for the relay terminal.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for operating a relay terminal that is located within a coverage of a network in a wireless communication system supporting inter-terminal communication and relays communication between a terminal and a base station outside the coverage of the network.

According to an aspect of the present invention, a method for operating a buffer state report (BSR) by a terminal in a wireless communication system supporting D2D (Device to Device) communication includes a first terminal located in a network coverage The method comprising the steps of: receiving data to be transmitted from a base station to a second terminal located outside a network coverage through a downlink; receiving data to be transmitted to the second terminal among data to be transmitted through D2D communication existing in a buffer in the first terminal; Triggering a BSR for the data, configuring a Media Access Control (MAC) control element for the triggered BSR, and transmitting a MAC control element for the configured BSR to the base station.

According to another aspect of the present invention, a relay terminal supporting D2D communication in a wireless communication system includes a radio frequency (RF) unit for receiving data to be transmitted from a base station to a remote terminal located outside a network coverage on a downlink, A controller for controlling the BSR of the data to be transmitted through the D2D communication existing in the buffer except the data to be transmitted to the remote terminal to be triggered, and a component configuring the MAC control element for the triggered BSR.

According to another aspect of the present invention, in a wireless communication system supporting D2D communication, a method of operating a base station transmits data to be transmitted to a second terminal located outside the network coverage to a first terminal located in a network coverage through a downlink Receiving a MAC control element for a BSR including information on data to be transmitted through the D2D communication in the first terminal from the first terminal, receiving a MAC control element for a BSR including information corresponding to the received MAC control element, And allocating resources corresponding to data to be transmitted to the first terminal.

According to another aspect of the present invention, a base station in a wireless communication system supporting D2D communication transmits data to be transmitted to a second terminal located outside network coverage to a first terminal located in a network coverage through a downlink, An RF unit for receiving a MAC control element for a BSR including information on data to be transmitted from the first terminal through D2D communication in the first terminal and a resource corresponding to the received MAC control element to the second terminal And allocating resources corresponding to the data to the first terminal.

According to the present invention, a base station can efficiently receive information on the amount of data to be transmitted from a terminal within a network coverage to a base station outside the network coverage, and can reduce unnecessary power consumption of the terminal in the network coverage.

1 is a diagram illustrating a wireless communication system to which the present invention is applied.
2 is a diagram for explaining a method of extending network coverage using a relay terminal based on D2D communication in a wireless communication system to which the present invention is applied.
3 is a diagram for explaining a wireless protocol defined in the present invention.
4 is a diagram for explaining a process of setting up a connection between a relay terminal, a base station and a core network according to the present invention.
5 is a diagram illustrating a procedure for establishing a one-to-one communication connection with a remote terminal according to the present invention.
6 is a diagram illustrating a PC5 signaling protocol stack used by a relay terminal according to the present invention.
7 is a diagram illustrating a relay terminal configuration procedure according to the present invention.
8 is a diagram showing a mapping relationship between bearers in the present invention.
9 is a diagram illustrating a method of operating a relay terminal according to the present invention.
10 is a diagram illustrating a format of an SL BSR MAC control element operated by a relay terminal according to the present invention.
11 is a view illustrating a subheader of an SL BSR MAC control element operated by a relay terminal according to the present invention.
12 is a diagram illustrating a method of operating a base station according to the present invention.
13 is a diagram illustrating a wireless communication system according to the present invention.
14 shows a PDCP data PDU used in the user plane.
FIG. 15 schematically shows an operating invention of a relay terminal according to an example of the present invention.
16 schematically illustrates an operation of the relay terminal according to another example of the present invention.
17 schematically shows an operation of a relay terminal according to another example of the present invention.

Hereinafter, the contents related to the present invention will be described in detail with reference to exemplary drawings and embodiments, together with the contents of the present invention. 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 included in the network.

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

The network structure shown in FIG. 1 may be a network structure of an Evolved-Universal Mobile Telecommunications System (E-UMTS). The E-UMTS system may include LTE (Long Term Evolution), LTE-A (advanced) systems, and the like.

Referring to FIG. 1, a base station (BS) and a user equipment (UE) 12 in a wireless communication system 10 can transmit and receive data wirelessly. Also, the wireless communication system 10 may support device to device (D2D) communication. D2D communication in a wireless communication system will be described later.

In the wireless communication system 10, the base station 11 can provide a communication service through a specific frequency band to terminals existing within the coverage of the base station. The coverage served by the base station may also be expressed in terms of a site. A site may include a plurality of areas 15a, 15b, 15c, which may be referred to as sectors. Each of the sectors included in the site can be identified based on different identifiers. Each of the sectors 15a, 15b, and 15c can be interpreted as a partial area covered by the base station 11.

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, and a remote radio head (RRH).

The terminal 12 may be fixed or mobile and may be a mobile station, a mobile terminal, a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant (PDA) , A wireless modem, a handheld device, and the like.

Also, the base station 11 may be referred to as various terms such as a megacell, a macrocell, a microcell, a picocell, a femtocell, etc., depending on the size of coverage provided by the corresponding base station. The cell may be used in terms of the frequency band provided by the base station, the coverage of the base station, or the term indicating the base station.

Hereinafter, a downlink (DL) refers to a communication or communication path from the base station 11 to the terminal 12, and an uplink (UL) refers to communication from the terminal 12 to the base station 11 Communication path ". 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 to the multiple access technique applied to the wireless communication system 10. For example, a CDMA (Code Division Multiple Access), a TDMA (Time Division Multiple Access), an FDMA (Frequency Division Multiple Access), an OFDMA (Orthogonal Frequency Division Multiple Access), an SC- , OFDM-TDMA, and OFDM-CDMA may be used. Also, a time division duplex (TDD) scheme or a frequency division duplex scheme (FDD) scheme using different frequencies may be used for uplink and downlink transmission.

2 is a diagram for explaining a method of extending network coverage using a relay terminal based on D2D communication in a wireless communication system to which the present invention is applied.

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 addition, D2D communication can be replaced with proximity based service (ProSe) or ProSe-D2D communication. The use of the term ProSe for D2D communication means that the meaning of data transmission / reception directly between terminals is not changed but the meaning of proximity based service can be added. In addition, an inter-terminal air interface and / or a wireless communication link in which the D2D communication is performed is defined as a side link (SL).

D2D communication is a discovery procedure for communication between terminals in network coverage (in-coverage) or out-of-coverage, and a direct communication (" direct communication procedures. Hereinafter, a terminal transmitting a signal based on D2D communication is referred to as a transmission terminal (Tx UE), and a terminal receiving a signal based on D2D communication is referred to as a reception terminal (Rx UE). The transmitting terminal can transmit a discovery signal, and the receiving terminal can receive a discovery signal. The roles of the transmitting terminal and the receiving terminal may be changed. A signal transmitted by a transmitting terminal may be received by more than one receiving terminal.

D2D communication can be used for various purposes. For example, D2D communications within network coverage based on commercial frequencies can be used for public safety, ultra-low latency services, and commercial-grade services. However, when based on public safety frequencies, D2D communications over that frequency can be used only for public safety, regardless of network coverage.

When terminals in close proximity in a cellular system perform D2D communication, the load of the base station can be dispersed. Also, when terminals close to each other perform D2D communication, the terminals transmit 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 is a communication between terminals located in an in-coverage area of a network coverage (base station coverage), communication between terminals located in an out-of-coverage area, communication between terminals located within a network coverage area .

Referring to FIG. 2, the communication between the first terminal 210 and the second terminal 220 may be a D2D communication within the network coverage. The communication between the third terminal 230 and the fourth terminal 240 may be a D2D communication outside the network coverage. The communication between the first terminal 210 and the third terminal 230 and the communication between the first terminal and the fourth terminal 240 may be a D2D communication between the terminal located within the network coverage and the terminal located outside the network coverage.

The base station 200 may schedule the resources required for the UEs 210 and 220 within the coverage to transmit data through the side link for D2D communication in the wireless communication system. In this case, each of the terminals 210 and 220 existing in the coverage determines how much data (D2D data) to be transmitted on the side link is stored in the intra-terminal buffer, through the buffer state report (BSR) 200). A BSR for a site link may be referred to as a SL BSR (Sidelink BSR) or a ProSe (Proximity Service) BSR to distinguish it from a BSR for a wide area network (WAN).

As one embodiment of performing D2D communication, the base station 200 may transmit D2D resource allocation information to the first terminal 210 located within the coverage of the base station 200. [ The D2D resource allocation information may include allocation information for transmission resources and / or reception resources that can be used for D2D communication between the first terminal 210 and the other terminals 220, 230, The first terminal 210 receiving the D2D resource allocation information from the base station transmits the D2D resource allocation information to be transmitted to the other terminals 220, 230, and 230 so that the first terminal 210 can receive the D2D data transmitted from the first terminal 210, 240).

The first terminal 210, the second terminal 220, the third terminal 230 and / or the fourth terminal 240 may perform D2D communication based on the D2D resource allocation information. Specifically, the second terminal 220, the third terminal 230, and / or the fourth terminal 240 may obtain information on the D2D communication resources of the first terminal 210. The second terminal 220, the third terminal 230 and / or the fourth terminal 240 may receive the D2D communication resources from the first terminal 210 through the resources indicated by the D2D communication resources of the first terminal 210 D2D data to be transmitted can be received. The first terminal 210 may transmit a request for allocation of resources for D2D communication with the second terminal 220, the third terminal 230 and / or the fourth terminal 240 from the base station 200, 210 to the base station 200 via the SL BSR. [0051] The base station 200 transmits the D2D data to the base station 200 via the SL BSR.

Meanwhile, since the first terminal 210 and the second terminal 220 are located within the network coverage, communication with the base station 200 is possible. That is, the first terminal 210 and the second terminal 220 can perform UL data transmission and DL data reception for the WAN through the base station 200. However, the third terminal 230 and the fourth terminal 240 outside the network coverage can not perform direct wireless communication with the base station 200. This is because the terminal can not communicate with another terminal, a base station, a server, or the like located in an area where a signal can not physically reach. However, when the fourth terminal 240 outside the network coverage requires a connection to the network for reasons such as public safety service or commercial service, and is capable of D2D communication with the first terminal 210 existing within the network service range through D2D communication The fourth terminal 240 outside the network coverage can transmit data to and receive data from the base station 200 via the indirect path if the first terminal 220 can perform a relay function. That is, the first terminal 220 acts as a relay terminal, and the base station 200 receives the WAN data to be transmitted to the fourth terminal 240 through the downlink, and transmits the WAN data to the fourth terminal 240 When the fourth terminal 240 receives data to be transmitted to the base station 200 via D2D communication and transmits the data to the base station 200 through the uplink, the third terminal 230 transmits the data to the base station 200 200 can be communicated. Hereinafter, a terminal located within a network coverage and relaying communication between another terminal and a base station is referred to as a relay terminal, and a terminal located outside a network coverage and communicating with a base station via a relay terminal is referred to as a remote terminal.

In general, in order for a terminal to perform a role of a relay terminal, in order to transmit / receive data to / from a remote access terminal to / from a remote terminal, a radio resource control connected state is set with a base station within a coverage of the base station It needs to be. However, when the relay terminal operates in the RRC idle mode and receives data requested to be transmitted from the remote terminal to the base station, the relay terminal starts the RRC connection establishment procedure to transmit the data to the base station, changes to the RRC connection mode, To the base station and may be changed to the RRC idle mode by the base station after the transmission is completed. Alternatively, when the relay terminal operates in the RRC idle mode and connection setup is completed in at least one or more remote terminals and the application layer (not a connection establishment in the wireless layer to an upper layer than the RRC layer) The RRC connection establishment procedure is started to transmit to the base station or the remote terminal, and the mode is changed to the RRC connection mode. If there is no remote terminal connected and configured in the application layer, the base station may change the RRC idle mode. Therefore, the relay terminal needs the RRC connection mode for the actual relay operation, but can maintain the relay terminal configuration irrespective of the RRC connection state.

3 is a diagram for explaining a wireless protocol defined in the present invention.

In FIG. 3, the PC 5 interface between the remote terminal 310 located outside the network coverage and the relay terminal 320 located within the network coverage can be defined as a wireless protocol interface which is implemented in the side link. Uu interface means a protocol interface defined in a radio link between a relay terminal 320 and a base station 330. [ The base station 330 is connected to an evolved packet core (EPC) through an S1 interface. The EPC can be connected to the AS (Application Server, 340) for public safety via the SGi interface.

4 is a diagram for explaining a process of setting up a connection between a relay terminal, a base station and a core network according to the present invention.

Referring to FIG. 4, the first MS 410 initially accesses an Evolved-UMTS Terrestrial Radio Access Network (UMTS) to access a wireless network, and transmits a Mobility Management Entity (MME) Home Subscriber Server). In addition, the first UE 410 may establish a connection to the PDN by performing a PDN (Packet Data Network) connection procedure (S410) (initial E-UTRAN Attach and / or UE requested PDN procedure).

The first terminal 410 may be changed to an EMM connected mode through the initial E-UTRAN connection and / or PDN connection procedure. The EMM connected UE may operate as an RRC idle mode terminal or as an RRC connected mode terminal. It means that the UE context information for the first UE 410 is stored in the upper network elements (MME 405 / HSS 400). An initial attach procedure, a tracking area update procedure, a handover, and a TAU procedure may be performed using the stored UE context information. In this regard, the upper networks can acquire / verify the location information of the terminal. In this way, it can be recognized by the upper network that the terminal belongs to a certain tracking area, and further, by using the PDN context information through the PDN connection procedure and the location information of the first terminal 410, (Bearer context) for packet data transmission for the mobile station.

That is, according to the present invention, the first terminal 410 supports the LTE service (LTE bearer setup) by connecting to the LTE system, and is a terminal supporting D2D communication, And D2D data with other terminals 430 located within the coverage of the base station or outside the base station coverage. Also, the first terminal 410 may transmit / receive information to / from the D2D terminal and the relay terminal for the present invention by the base station through the UE capability procedure and / or the ProSe UE information procedure. Herein, the BS determines the first terminal 410 as a relay terminal through the UE capability procedure and / or the ProSe UE information procedure, and configures the first terminal 410 as a relay terminal through an RRC connection reconfiguration procedure. Or the first terminal 410 recognizes that the corresponding cell provides parameters related to the relay terminal configuration through the information broadcast by the base station and when it is determined that the first terminal 410 can be configured as a relay terminal And a relay terminal. That is, the first terminal 410 supporting D2D communication can operate as a relay terminal when configured as a relay terminal through a base station.

The first terminal 410 acting as the relay terminal may operate as a Model A or Model B. The Model A is a form of "I'm here" in which the first terminal 410 transmits information including its own information in a discovery message. Model B is "Who's there?" Or "Is UE1 there?" Refers to a form in which information including a specific condition to be searched for or a specific terminal is transmitted and information that requests a response when the corresponding condition or terminal is correct is transmitted in a discovery message.

The third terminal 430 located outside the coverage of the base station finds the relay terminal through the discovery procedure (acquires the discovery signal transmitted by the first terminal 410) and selects the relay terminal (S420) discovery procedure, and may perform a procedure for establishing a one-to-one communication connection between the relay terminals by operating as a remote terminal (S430) (Establishment of connection for One-to-One Communication). At this time, the procedure for establishing a one-to-one communication connection between the remote terminal and the relay terminal may include the following secure layer-2 establishment procedure.

FIG. 5 is a diagram illustrating a procedure for establishing a one-to-one communication connection with a relay terminal according to the present invention, and FIG. 6 is a diagram illustrating a PC5 signaling protocol stack used by a relay terminal according to the present invention.

Referring to FIG. 5, the terminal A can request direct communication for mutual authentication to the terminal B based on the PC5 interface (S510) (Direct communication request). Here, the terminal A may be a remote terminal and the terminal B may be a relay terminal. For this, the terminal A needs to know the second layer (layer-2) ID of the terminal B. For example, the terminal A determines the second layer ID of the terminal B included in the discovery message transmitted by the terminal B as a relay terminal or participates in the one-to-many communication including the terminal B to find out the second layer ID of the terminal B (learn). Here, the second layer ID is terminal identification information used in a second layer that hosts a PDCH / RLC / MAC entity, and includes a source layer 2-ID field and a destination layer 2-ID Field. Here, the source layer 2 ID field carries the identity of the source (carries). It can be used as a ProSe UE ID. The size of the SRC field is 24 bits, and the DST field carries the 16 most significant bits of the destination layer-2 ID (carries). The Always Destination Layer 2 ID can be used as the ProSe Layer-2 Group ID. Upon receiving a direct communication request from the terminal A, the terminal B performs a mutual authentication procedure and establishes a secure layer-2 link based on the PC5 interface (S520) (Authentication and establishment of security association ).

The terminal performing the secure layer-2 link procedure includes a physical layer (PHY) layer 605, a medium access control (MAC) layer 605, (RLC) layer 615, a Packet Data Convergence Protocol (PDCP) layer 620, and a PC 5 signaling protocol layer 625.

The PHY layer 605 provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to the MAC layer, which is an upper 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. Data is transferred between the PHY layers through the physical channel. The physical channel can be modulated by an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and utilizes time, frequency, and space generated by a plurality of antennas as radio resources.

The MAC layer 610 multiplexes data into a transport block provided on a physical channel on a transport channel of a MAC SDU (Service Data Unit) belonging to a logical channel and a mapping between a logical channel (LC) Or demultiplexing. The MAC layer provides a service to the RLC layer through a logical channel. The logical channel can be divided into a control channel for transferring control area information and a traffic channel for transferring user area information. For example, there are data transmission or radio resource allocation as services provided from the MAC layer to the upper layer.

The function of RLC layer 615 includes concatenation, segmentation and reassembly of RLC SDUs. RLC SDUs are supported in various sizes, and may be supported on a byte basis, for example. RLC Protocol Data Units (PDUs) are defined only when a transmission opportunity from a lower layer (eg, the MAC layer) is notified and forwarded to the lower layer. The transmission opportunity may be notified with the size of the total RLC PDUs to be transmitted. In addition, the transmission opportunity and the size of the total RLC PDUs to be transmitted may be separately reported.

The function of the Packet Data Convergence Protocol (PDCP) layer 620 includes transmission of user data, header compression and ciphering, transmission of control plane data, and encryption / integrity protection.

The PC5 signaling protocol layer 625 is responsible for transferring D2D data. As shown in the following Table 1, the SDU type field value in the PDCP header can discriminate that the corresponding SDU is data for the PC5 signaling protocol. The terminal A and the terminal B perform signaling for the Secure Layer-2 establishment procedure as shown in FIG. 5 through the PC5 signaling protocol.

Bit Description 000 IP 001 ARP 010 PC5 Signaling Protocol 011-111 reserved

7 is a diagram illustrating a relay terminal configuration procedure according to the present invention.

A terminal supporting D2D communication can perform D2D communication when it connects to a D2D application server (or a ProSe application server) and has successfully completed the D2D operation authentication procedure and has been allocated an identifier (ID) to be used in the D2D operation . The identifier may include a source ID, a destination ID, and the like. Here, the source ID may be assigned only one ID unique to each terminal, but a plurality of IDs may be assigned to the destination ID according to the purpose of the corresponding D2D communication. That is, if the terminal directly requests ID information for a plurality of different destinations according to the terminal characteristics (for example, access rights, etc.) based on the terminal information, the D2D application server sends one It is possible to assign a plurality of destination IDs to the terminals of the terminal device.

In addition, the terminal can perform D2D communication when a user of the terminal sets the terminal to enable D2D communication through a user interface (UI). Alternatively, the D2D communication of the D2D terminal may always be set to the permissible state, and the user may be unchangeable.

On the other hand, if the terminal is located within the cellular service area (network coverage), i.e., can receive and recognize signals transmitted by the base station for cellular services, the terminal is assigned ID (s) to use in the D2D operation, The D2D communication can be performed only when the base station transmits a message including information for allowing the D2D operation. That is, the terminal can perform D2D communication only when it receives a message from the base station, including a message that allows D2D operation. Here, the information for allowing the D2D operation may be defined as a system information block (SIB) including configuration information for each of the communication and the discovery in the D2D operation is received from the base station.

The 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. In this case, when the terminal performs D2D communication, the terminal must transmit the BSR for the D2D data to the base station or the cluster head. Hereinafter, the BSR for the D2D data is referred to as a Side Link (SL) BSR. In addition, the cellular network can be replaced with the term wide area network (WAN).

A logical channel (hereinafter referred to as PC5 LC) for D2D communication is distinguished from an LC (hereinafter referred to as WAN LC) for WAN (e.g., LTE) communication. The PC5 LC may be composed of a plurality of PCs in a single terminal, and each of the PC5 LCs may be provided with a Source Layer-2 ID, a Destination Layer-2 ID, and an LCID (Logical Channel ID) Lt; / RTI >

Referring to FIG. 7, when a base station receives D2D terminal (ProSe UE) information from a terminal supporting D2D communication (S710), the base station determines whether the terminal can perform a role of a relay terminal, The relay configuration information may be transmitted to the corresponding terminal (S720). In addition, the base station can receive the terminal information and the capability information of the terminal from the terminal. That is, the BS determines whether the UE capability information (UE capability information) transmitted from the UE and the D2D UE information (ProSe UE information) are configured as a relay terminal (S720).

Alternatively, when the base station receives the terminal information (ProSe UE) from a terminal supporting a plurality of D2D communication in the cell (S710), it determines whether at least one terminal can perform a role of a relay terminal based on the information And may include the relay configuration information in the system information (S720). Therefore, the relay configuration information can be received by all the terminals in the cell, but only the terminal capable of performing the role of the relay terminal can operate as the relay terminal.

Alternatively, when the base station receives the terminal information (ProSe UE) from a terminal supporting a plurality of D2D communication in the cell (S710), it determines whether at least one terminal can perform a role of a relay terminal based on the information (For example, a discovery procedure-related parameter in the case of operating as a relay terminal) of all the relay terminals in the relay information of the system information and transmits relay configuration information (for example, The source ID assigned to each relay terminal) through the RRC reconfiguration procedure (S720).

Here, the RRC reconfiguration procedure for configuring the necessary relay configuration information only for the terminal may be provided when the relay terminal needs to operate in the RRC connected mode. That is, it can be provided through the RRC connection reconfiguration procedure immediately after establishing the RRC connection. Also, the terminal information may include information on capability of the terminal and / or information on whether the terminal intends to operate as a relay terminal.

The terminal receiving the relay configuration information from the base station can operate as a relay terminal (S730). For example, the relay configuration information may include parameters necessary for the corresponding terminal to operate as a relay terminal. Herein, the parameters necessary for operating the relay terminal include a relay signal included in a synchronization signal in a discovery message and a relay identifier included in a system message transmitted so that a plurality of relay terminals can be distinguished by a remote terminal in a single cell, Parameters.

Upon receiving the relay configuration information, the terminal can recognize that the base station implicitly instructs the base station to operate as a relay terminal. Alternatively, the relay configuration information may include information directly indicating that the corresponding terminal operates as a relay terminal, in addition to the parameters. That is, the base station can directly configure or release the relay terminal.

Alternatively, the relay configuration information may include RS-RSRP (Reference Signal Received Power) of a base station and / or SLRS (Side Link Sync Signal) based on a remote terminal or DM-RS (Demodulation-reference signal) Sidelink-RSRP). ≪ / RTI > In this case, the terminal can determine whether to operate the relay terminal based on the threshold value. That is, the base station can allow the relay operation of the corresponding terminal through the parameter configuration, and if the relay operation is allowed, the terminal can determine whether to operate the relay terminal based on the threshold value.

In another example, the base station may provide only configuration information to the terminal, whether or not to permit the operation of the relay terminal, and may not provide the parameters necessary for the operation of the relay terminal. In this case, the terminal can determine whether to operate the relay terminal on its own basis.

The relay terminal can operate in the first transmission mode and the second transmission mode in the D2D communication. The first transmission mode is a mode that can perform D2D communication only when a terminal is allocated resources for D2D communication from a base station, and may be called a scheduling resource selection mode. The base station is configured in a first transmission mode and can transmit a D2D grant to a terminal in which data to be transmitted exists via a side link. In the D2D communication, the D2D grant transmits side link control information (SCI: Sidelink control information), which is control information to be secured for receiving D2D data at the receiving side terminal, and PSSCH (Physical Sidelink Shared Channel) indicated by the SCI, To assign a resource allocation for a resource. The resource allocation is transmitted to the transmitting terminal through downlink control information (DCI), and the DCI is an SL-RNTI (Sidelink-Radio Network Temporary Identifier) for indicating physical layer control information for the side link. (Physical Downlink Control Channel (PDCCH) or Extended PDCCH (EPDCCH) scrambled with a value of < RTI ID = 0.0 > The D2D grant may be referred to as a side link grant (SL grant). The UE operates in the first transmission mode except for some exceptional cases such as when an RRC connection reconfiguration message is transmitted from the base station and an SL-RNTI is configured, a problem occurs in the radio link with the base station, can do.

Meanwhile, the second transmission mode is a mode in which the UE can perform D2D communication regardless of the indication of the BS, and may be called an autonomous resource selection mode. The terminal may internally select a resource to use among the radio resources (for example, time, frequency, space, etc.) available in the second transmission mode in the D2D communication, and transmit the D2D data. If the UE determines that it is located within the cellular service area, that is, if it determines that at least one suitable cell is present, the base station specific cell transmits a D2D through a system information block (SIB) / dedicated signaling And / or D2D resource pool information for a second transmission mode provided by the base station exists in the second transmission mode. However, if the base station does not allow operation in the second transmission mode, the UE can not operate in the second transmission mode even though the D2D resource pool information exists. If the terminal is located outside the network coverage, the terminal may use the D2D resource pool information for the second transmission mode stored in an internal device such as UICC (USIM (Universal Subscriber Identity Module) Integrated Circuit Card) The mobile station can operate in the second transmission mode using the D2D resource pool information for the second transmission mode received through the base station in the network service area.

8 is a diagram showing a mapping relationship between bearers in the present invention.

The logical channels in the PC5 interface established between the remote terminals UE1 and UE2 810 and 820 and the relay terminal 805 are connected to the relay bearer 805 and the EPS bearer connected to the E-UTRAN / Lt; / RTI > In this case, the logical channels in the PC5 interface may be mapped to the EPS bearer one-to-one and one-to-many mapped (multiple PC5 LC mapped to one EPS bearer).

For example, the first PC5LC to the third PC5LC to the first remote terminal are mapped to the first EPS bearer, and the fourth PC5LC to the sixth PC5LC to the second remote terminal are mapped to the second EPS bearer Fig.

The mapping can be configured by the relay terminal itself. For example, if it is assumed that the base station configures the first EPS bearer to support VoIP (voice over IP) and the second EPS bearer supports the video service for the purpose of supporting the remote terminal, The MS can configure the mapping relationship to correspond to the characteristics of the EPS bearers in consideration of the traffic characteristics of each PC 5 LC configured by the remote terminals connected to the MS and the priorities of the remote terminals based on the information .

The PC 5 LC-specific traffic characteristics and priority for each remote terminal can be provided to the relay terminal through the application layer when the application layer connection is established between the relay terminal and the remote terminal.

In another method, the relay terminal confirms information indicating priority in each packet received from the base station to transmit to the remote terminal, and operates based on this information. The packet may be a PDCP SDU or a PDCP PDU. The priority information may be included in the PDCP SDU or the PDCP PDU, or may be included in the PDCP header. The information indicating the priority may be defined in ascending order of 8 different priorities or 16 different priorities in 3 bits, or 32 different priorities in ascending order by 5 bits.

14 shows a PDCP data PDU used in the user plane. Referring to FIG. 14, the most significant bit (MSB) is the leftmost bit of the first line of the bit string represented in FIG. The PDCP data PDU may be referred to as a PDCP PDU. Here, PPP stands for priority per packet. The PPP field is located immediately after the sequence number (PDCP SN) field indicating the corresponding SDU and PDU except for the spare field (R). The D / C field is a field for indicating whether the corresponding PDCP PDU is for user data (data PDU) or control information (control PDU).

The PPP information in the PDCP SDU may be configured at the MSB position of the bit string constituting the PDCP SDU, or at the end of the PDCP SDU as shown in FIG.

If the total number of configurable logical channels is less than the number of different priorities currently set for each packet, packets with different priorities may be included in a single logical channel, Is determined as a packet having the highest priority among the packets included in the logical channel. Therefore, the EPS bearer configured to transmit data to the remote terminal can have a mapping relation only to the PC5 logical channels set for the specific remote terminal, and the priority of the PC5 logical channel is the most It can be changed according to a packet having a high priority.

Also, the relay terminal can transmit a general D2D data and configure a logical channel for the D2D data transmission. The logical channels set for transmitting the general D2D data can also set a priority for each packet generated by the application in the relay terminal, and the priority of the logical channel configured to transmit the logical channels is determined based on the priority of the packets included in the logical channel And is determined as a packet having the highest priority.

FIG. 15 schematically shows an operating invention of a relay terminal according to an example of the present invention.

Referring to FIG. 15, the relay terminal may determine the priority of each logical channel by combining the PC5 logical channels for the general D2D data transmission and the PC5 logical channels for transmitting the relay data to the remote terminal. In this case, the MAC PDU is configured by selecting data having a logical channel having the highest priority among the general D2D data or the relay data for a single transmission resource configurable based on the SLgt information received from the base station for SL resource allocation .

16 schematically illustrates an operation of the relay terminal according to another example of the present invention. Referring to FIG. 16, the relay terminal may separate the PC5 logical channels for the general D2D data transmission and the PC5 logical channels for transmitting the relay data to the remote terminal, and determine the priorities in the respective categories. At this time, all the PC 5 logical channels for transmitting to the remote terminal so that the SL radio resource provided by the base station to the relay terminal through the SL grant signaling can be preferentially used for data transmission within all the PC 5 logical channels for transmitting to the remote terminal May have higher priority than PC5 logical channels for normal D2D data transmission.

FIG. 17 schematically shows an operating invention of a relay terminal according to another example of the present invention.

Referring to FIG. 17, it is possible to completely separate the PC5 logical channels for the general D2D data transmission and the PC5 logical channels for transmitting the relay data to the remote terminal, and may operate in different MAC layers.

9 is a diagram illustrating a method of operating a relay terminal according to the present invention.

The terminal supporting the D2D service can inform the base station through the SL BSR of the amount of data (SL data) to be transmitted through the D2D communication through the side link in the buffer when operating in the first transmission mode. To this end, the conditions for triggering the SL BSR are defined in the wireless communication system as shown in Table 2 below.

A sidelink Buffer Status Report (BSR) shall be triggered if any of the following events occur:
- if the MAC entity has a configured SL-RNTI:
- SL data, for a sidelink logical channel of a ProSe Destination, becomes available for transmission in the RLC entity or PDCP entity (the definition of what data is to be used for transmission is specified) for transmission of any of the sidelink logical channels belonging to the same ProSe Destination, in which case the Sidelink BSR is referred to as "Regular Sidelink BSR";

According to the SL BSR triggering condition as shown in Table 2, when the relay terminal receives data to be transmitted from the base station to the remote terminal through the WAN DL, it must transmit the SL BSR through the side link.

Meanwhile, the base station according to the present invention can determine the amount of data to be transmitted to the MS over the WAN DL, that is, the amount of data to be transmitted to the MS through the relay link (higher layer PC 5) The QoS of the data to be transmitted to the remote terminal is known to the terminal. This is because the D2D terminal configured by the base station as the relay terminal can manage / configure the mapping relationship between the EPS bearer and the logical channels in the PC5 interface. The mapping between the service bearers may be configured by a relay terminal. This is as described in FIG.

Alternatively, the mapping relationship between the PS bearer and the logical channels in the PC5 interface may be managed / configured by the base station. When the relay terminal completes the one-to-one connection setup with the remote terminal, the relay terminal reports the newly generated PC5 LCs to the base station, and based on the configuration information, the base station transmits the configuration information about the mapping relationship between the EPS bearer and the logical channels in the PC5 interface Can be provided. Where the PC5 LCs are bi-directional channels. That is, data transmission and reception are all performed on the basis of the same PC5 LC.

The SL BSR triggering operation (SL BSR triggering operation) according to the conditions described in Table 2 is performed by the D2D terminal operating as a relay terminal by the configuration of the base station (or by the parameter configuration or autonomous configuration of the terminal) ) May cause unnecessary SL BSR operation for the D2D terminal. The SL BSR operation may additionally cause unnecessary operations such as an SR transmission request / SL grant between the base station and the D2D terminal.

Therefore, the present invention needs to modify the SL BSR triggering condition / SL BSR transmission condition of the D2D terminal. As described above, the D2D terminal configured as a relay terminal according to the present invention confirms the existence of data to be transmitted to the remote terminal among the data received from the base station via the WAN DL when the generation of data to be transmitted through the side link is confirmed, When there is data to be transmitted to the terminal, the SL BSR is triggered on the SL data excluding the data received from the base station to transmit to the remote terminal among the generated SL data.

This is because the base station acquires the mapping relationship between the EPS bearer and the logical channels in the PC 5 interface by the relay terminal, that is, the mapping relationship between the EPS bearer and the logical channels in the PC 5 interface Data to be transmitted to the remote terminal so that the QoS of the data can be satisfied without receiving information on the amount of data through the SL BSR from the relay terminal (WAN DL To the relay terminal.

Therefore, according to the present invention, the D2D terminal can trigger the SL BSR according to the conditions shown in Table 3. [

A sidelink Buffer Status Report (BSR) shall be triggered if any of the following events occur:
- if the MAC entity has a configured SL-RNTI:
- SL data, for a sidelink logical channel of a ProSe Destination, becomes available for transmission in the RLC entity or PDCP entity (the definition of what data is to be used for transmission is specified in [3] and [4] The ProSe Destination, which is the Sidelink BSR, is referred to below as "Regular Sidelink BSR" except for the ProSe Destination of SL data is "Remote" ;;

Referring to FIG. 9, a D2D terminal configured as a relay terminal confirms a destination type of generated data (S900).

When the D2D terminal configured as the relay terminal confirms the data to be transmitted to the remote terminal located outside the network coverage through the downlink from the base station, that is, if it is confirmed that the destination type for transmitting the generated data is the remote terminal (S900) The relay terminal does not trigger the SL BSR (910).

Alternatively, the D2D terminal configured by the relay terminal may transmit a logical channel (LC) including data to be transmitted to a remote terminal located outside the network coverage through a downlink from a base station to a logical channel group: LCG). That is, when it is confirmed that the destination type of the logical channel to which the data to be transmitted is the remote terminal (S900), the logical channels including the data to be transmitted to the remote terminal are not included in any logical channel group, (910). Therefore, the SL BSR can be triggered according to the conditions shown in Table 4.

Each sidelink logical channel is allocated to an LCG except for remote UEs and belongs to a ProSe Destination.

A sidelink Buffer Status Report (BSR) shall be triggered if any of the following events occur:
- if the MAC entity has a configured SL-RNTI:
- SL data, for a sidelink logical channel belonging to a LCG of a ProSe Destination, becomes available for transmission in the PDCP entity (the definition of what data is to be used for transmission is specified in [3] and [4] respectively) and there is currently no data available for transmission of any of the logical channels belonging to the LCG of same ProSe Destination, in which case the Sidelink BSR is referred to as "Regular Sidelink BSR";

The LCG may include at least one or more LCs and may have a value ranging from 0 to 3 for each destination layer-2 ID.

The mapping between the LC for the D2D communication (hereinafter referred to as SLLC) and the LCG is performed in the terminal, and the priority of the LCG is determined according to the highest priority value among the packets in the LC included in each LCG. The priority of the packets in the LC to be included in each LCG may be determined by the BS and configured to the UE through RRC signaling or the like. The UE determines the priority of the packets in the LC to be included in each LCG, Based on this, the base station may configure the terminal through RRC signaling or the like.

For example, the base station can set priority within each LCG as follows. First, LCG value '0' maps priorities 1 and 2 and LCG value '1' maps to priorities 3, 4 and 5. LCG value '2' maps priorities 6 and 7 and finally LCG value ' Can set information to be mapped as priority 8. The above configuration can be configured differently for each terminal. You can also configure information for some LCGs, not just for all LCGs.

On the other hand, when there is data to be transmitted from the base station to the remote terminal located outside the network coverage through the downlink from the base station and the relay terminal confirms that there is data to be transmitted to the destination other than the remote terminal (S920), the relay terminal can trigger the SL BSR if D2D data does not exist (S900) when the destination data of the generated data is other than the remote terminal.

The relay terminal is triggered by the SL BSR and transmits data to be transmitted to the remote terminal among the data (SL data) to be transmitted through the D2D communication existing in the buffer in the relay terminal except for the transfer destination of the rest of the destinations The relay terminal configures a MAC Control Element (CE) for the SL BSR and transmits the configured SL BSR MAC CE to the BS in step S930. .

If SL BSR is triggered and data to be transmitted through the D2D communication existing in the buffer in the relay terminal (SL data) is not included in the remaining destinations except the data to be transmitted to the remote terminal, In the case where an uplink grant which can be transmitted including only some information is secured, a MAC Control Element (CE) for a truncated SL BSR may be configured and the configured SL BSR MAC CE may be transmitted to the BS in operation S930. . Hereinafter, the format of the SL BSR MAC CE will be described later.

Upon receiving the SL BSR MAC CE from the relay terminal, the base station can allocate resources corresponding to the SL data present in the buffer in the relay terminal. Here, the resource corresponding to the SL data existing in the buffer in the relay terminal may include a resource corresponding to the amount of data reported to the BS through the SL BSR MAC CE and a resource corresponding to data to be transmitted to the relay terminal. In other words, since the base station knows information on the amount of data to be transmitted to the remote terminal through the side link, in addition to the information on the amount of data reported through the SL BSR MAC CE in the buffer in the relay terminal, Resources corresponding to the data can be allocated.

On the other hand, the relay terminal not only serves as a relay terminal for a remote terminal but also can perform general D2D communication with other terminals. It is also possible to perform general D2D communication instead of data transmission / reception as a relay with a remote terminal. Accordingly, when the relay terminal operates as a relay, it can simultaneously configure the ProSe UE ID used in the secure layer-2 establishment procedure and the ProSe UE ID for general inter-terminal communication.

In other words, the source ID / destination ID used in the case of operating as a relay terminal and the source ID / destination ID used in general D2D communication are different from each other and can be configured in the relay terminal at the same time. Here, the ProSe UE ID (source ID and destination ID) to be used as a relay terminal may be allocated to the base station, the E-UTRAN, and the base station when the relay terminal is allocated from the ProSe application server or configured as a relay terminal Or from an EPC. Here, each ProSe UE ID can be configured through one of the following methods.

An ID (unicast ProSe UE ID) used for a one-to-one connection between a remote terminal and a relay terminal and an ID (groupcast ProSe UE ID) used for general D2D communication are distinguished by one bit in a UE ID (UE ID) The terminal ID can be allocated within a predetermined range of the range to which the terminal ID can be allocated. Alternatively, the MAC layer can distinguish between the IDs used for the one-to-one connection between the remote terminal and the relay terminal and the IDs used for the general D2D communication with different MAC headers. Alternatively, the destination layer-2 ID used by the remote terminal and the relay terminal for one-to-one connection may be configured so that there is only one terminal indicated by the destination layer-2 ID .

FIG. 10 is a diagram illustrating a format of an SL BSR MAC control element operated by a relay terminal according to the present invention, and FIG. 11 is a diagram illustrating a subheader of an SL BSR MAC control element operated by a relay terminal according to the present invention.

Referring to FIG. 10, an example of the MAC CE of the SL BSR is shown. There may be a plurality of destinations that can transmit data through a side link in D2D communication. The object may comprise one or more terminals. Therefore, the SL BSR MAC CE may include buffer state information for a plurality of objects as shown in FIG. 10 (a) and FIG. 10 (b), but when the target is a remote terminal, (I.e., data to be transmitted to the remote terminal among the data (SL data) to be transmitted through the D2D communication existing in the buffer in the relay terminal is excluded), and the destination of the remaining destinations among the destinations As shown in FIG. 5A, only a part of the D2D data information is included.

In Fig. 10, N is the number of objects having transferable data. The SL BSR MAC CE is configured as shown in FIG. 10 (a) when the number of groups (N) included in the SL BSR is an even number, and is configured as shown in FIG. 10 (b) when the number is an odd number. When the number of groups included in the SL BSR is an odd number, the SL BSR MAC CE may include four reserved bits as shown in FIG. 10 (b). Here, the group index has a length of 4 bits as a value for confirming an object to which ProSe (D2D) data is transmitted. This value is set to the index of the destination ID reported by the terminal as RRC signaling. Specifically, when the terminal transmits a ProSe destination information list (ProseDestinationInfoList) including a ProSe destination ID having a length of 24 bits to the base station, the base station transmits the group index 4 (for example, in ascending order) Bit) is mapped from 0 to a maximum of 15.

For example, when the UE has allocated two ProSe Destination IDs through the ProSe application server (or the base station / E-UTRAN / EPC), the UE transmits a ProSe Destination ID to be mapped to the group index 0 to the ProSe destination information list And a ProSe Destination ID to be mapped to the group index 1 is configured as a second in the ProSe destination information list and can be transmitted as an RRC message to the base station. The base station that has received the ProSe destination information list maps the first configured ProSe Destination ID to the group index '0', and maps the second configured ProSe destination ID to the group index '1'. That is, the base station can acquire the destination information indicated by the corresponding index through the 4-bit group index transmitted from the terminal. More specifically, the terminal may construct a list including 16 pieces of destination information corresponding to the group indices 0 to 15 (assign a group index corresponding to the list up sequence) and transmit the group list to the base station, And transmit the list including the corresponding number of destination information to the base station. Here, the configuration of the list including the destination information corresponding to the group index does not restrict other changes of the present invention.

 The LCG ID is for identifying the logical channel group for which the buffer status is reported to the base station. The LCG ID may be assigned an LCG ID of 0 to 3 for each group index. Alternatively, the LCG IDs may be allocated from 0 to 3 on the basis of a logical channel separately from each group index. In this case, transmittable data can be distinguished on the basis of each object within the same LCG ID, And each group index.

Conversely, transmittable data can be distinguished on the basis of each LCG ID within the same object, which can be represented by a combination of the object and each LCG ID. The buffer size field is a field for storing data available for all logical channels in the combination, considering all combinations of the objects and LCGs described above after all the MAC PDUs to be transmitted during one transmission time interval (TTI) In order to identify the total amount of the < / RTI > As described above, the SL BSR MAC CE may include buffer status information for a plurality of targets. However, if the target does not have data that can be transmitted through the side link or if the target is a remote terminal, the buffer status information is included in the SL BSR MAC CE (I.e., data to be transmitted to the remote terminal among the data (SL data) to be transmitted through the D2D communication existing in the buffer in the relay terminal is excluded), and for the rest of the destinations, By including only some D2D data information, the SL BSR MAC CE can have a variable length.

If the LC including the data to be transmitted to the remote terminal in the SL BSR triggering condition can not be included in any LCG, since there is no LCG information required to be included in the SL BSR MAC CE, the LCs configured for transmission to the remote terminal The buffer status information for the SL BSR can not be included in the SL BSR MAC CE.

On the other hand, the subheader of the SL BSR MAC CE can be configured as shown in FIG. In FIG. 11, a 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 (L) field indicates a length of the MAC SDU or indicates a length of a variable-sized MAC CE. The L field includes one per sub-header except for the last sub-header and the sub-header corresponding to the fixed-size MAC CE in the MAC PDU. According to the present invention, in the L field, data to be transmitted to the remote terminal among the data (SL data) to be transmitted through the D2D communication existing in the buffer in the relay terminal is excluded, and, in the rest of the destinations, It is possible to indicate the length of the MAC CE when only a part of the D2D data information is included.

The F field is a field for indicating the length of the L field, the extension field (E) is a field for identifying whether other fields are present in the MAC header, and the R (Reserved) field is a reserved field. do.

The amount of data occupied by the subheader of the SL BSR MAC CE is composed of 16 bits including the L field since the SL BSR has a variable length. This is generated every time the periodic ProSe-BSR timer expires and is transmitted on the uplink.

12 is a diagram illustrating a method of operating a base station according to the present invention.

Referring to FIG. 12, the base station can transmit relay configuration information to a terminal supporting D2D communication (S1200). At this time, the BS can determine whether to configure the D2D terminal as a relay terminal by checking UE capability information (UE capability information) and D2D terminal information (ProSe UE information) transmitted from the D2D terminal. The base station may configure or release the relay terminal directly. Alternatively, the D2D terminal can control the relay terminal to allow the D2D terminal itself to determine whether to operate the relay terminal itself based on the threshold value through the parameter or through the parameter configuration. Or only whether the relay terminal operation is permitted or not, and may not provide the parameters necessary for the relay terminal operation.

According to the present invention, the BS acquires the mapping relationship between the EPS bearer and the logical channels in the PC 5 interface by the relay terminal, thereby recognizing the bearer setting mapping relationship of the data to be transmitted to the remote terminal through the relay terminal have. The base station can transmit the uplink resource allocation information (grant) to the relay terminal, and can transmit the data to be transmitted to the remote terminal to the relay terminal (S1210).

Here, when the relay terminal receives the uplink grant from the base station, the relay terminal can inform the base station of the amount of data to be transmitted through the side link to the buffer in the relay terminal by transmitting the SL BSR MAC CE to the base station. At this time, the SL BSR MAC CE transmitted by the relay terminal may exclude information on the amount of data transmitted from the base station to the relay terminal for transmission to the remote terminal. In this regard, when the destination type of the data generated by the relay terminal is a remote terminal, the relay terminal does not trigger the SL BSR and may not configure the SL BSR. Therefore, in this case, the base station does not expect to receive the SL BSR from the terminal (relay terminal) (S1220). On the other hand, when the BS receives the SL BSR MAC CE from the relay terminal, it is determined that there is data to be transmitted to the remote terminal by the relay terminal according to the present invention and that there is data to be transmitted to the destination other than the remote terminal In this case, if the SL BSR is triggered, the SL BSR configured for the D2D data excluding the data to be transmitted to the remote terminal may be received (S1220).

The base station considers a resource corresponding to the amount of data to be delivered to the remote terminal or a resource corresponding to the amount of data included in the received SL BSR MAC CE through the mapping relationship between the EPS bearer and the logical channels in the PC 5 interface, And can perform resource allocation to the relay terminal. Through the resource allocation, the BS can allow the relay terminal to perform D2D communication with the other terminal and to transmit data to be transmitted to the remote terminal through the side link (S1230).

13 is a diagram illustrating a wireless communication system according to the present invention.

Referring to FIG. 13, a wireless communication system supporting inter-terminal communication according to the present invention includes a terminal 1300 and a base station 1400.

The terminal 1300 includes a processor 1310, an RF unit (radio frequency unit) 1320, and a memory 1330. The memory 1330 is coupled to the processor 1310 and stores various information for driving the processor 1310. [ RF section 1320 is coupled to processor 1310 to transmit and / or receive wireless signals. For example, the RF unit 1320 may receive, from the base station 1300, uplink resource allocation information, relay configuration information, side link resource allocation information, and the like disclosed herein. In addition, the RF unit 1320 may transmit the uplink signals, such as the ProSe UE information and the SL BSR, to the base station 1400.

Processor 1310 implements the functions, processes and / or methods suggested herein. For example, the processor 1310 may include a determination unit 1311, a control unit 1312, and a configuration unit 1313.

When the terminal 1300 is configured as a relay terminal, the determination unit 1311 can determine whether there is data to be transmitted to the remote terminal in the buffer in the terminal 1300. [ For example, the terminal 1300 transmits the D2D terminal (ProSe UE) information and / or the capability information of the terminal to the base station 1400 through the RF unit 1320 and receives the relay configuration information from the base station 1400 And a relay terminal. The determination unit 1311 can confirm the destination type of data generated in the buffer in the terminal 1300 when the terminal 1300 is configured as a relay terminal.

If it is determined by the determination unit 1311 that there is data to be transmitted to the remote terminal, the control unit 1312 transmits data excluding the data to be transmitted to the remote terminal among the data to be transmitted through the D2D communication existing in the buffer in the terminal 1300 Lt; RTI ID = 0.0 > BSR < / RTI > For example, the controller 1312 may control the SL BSR not to be triggered when the determination unit 1311 determines that the destination type of data generated in the buffer in the terminal 1300 is for the remote terminal. However, if the data to be transmitted to the remote terminal among the destination types of the data generated in the buffer in the terminal 1300 is not included in the determination unit 1311 and data that can be transmitted through the side link exists, The BSR can be controlled to be triggered.

The configuration unit 1313 configures the SL BSR MAC CE when the SL BSR is triggered. When the SL BSR MAC CE is configured, the RF unit 1320 transmits it to the base station 1400 through the uplink.

The memory 1330 may store uplink resource allocation information, side link resource allocation information, relay configuration information, and the like according to the present specification, and may provide it to the processor 1310 according to the request of the processor 1310.

The base station 1400 includes an RF unit (radio frequency unit) 1410, a processor 1420, and a memory 1430. The memory 1430 is coupled to the processor 1420 to store various information for driving the processor 1420. RF section 1410 is coupled to processor 1420 to transmit and / or receive wireless signals. Processor 1420 implements the functions, processes, and / or methods suggested herein. The operation of the base station 1400 in the above-described embodiment may be implemented by the processor 1420. [ The processor 1420 generates uplink resource allocation information, side link resource allocation information, relay configuration information, and the like, which are posted herein, and schedules resources for D2D communication based on the SL BSR received from the terminal 1300 .

In one example, the processor 1420 may include a determination unit 1421, a configuration unit 1422, and an allocation unit 1423.

The determination unit 1421 can determine whether relaying of the corresponding terminal is possible based on the terminal information received from the terminal and / or the capability information of the terminal.

The configuration unit 1422 may configure the relay configuration information when the determination unit 1421 determines that the terminal that transmitted the terminal information and / or the capability information of the terminal is capable of relaying. For example, the relay configuration information may include parameters necessary for the corresponding terminal to operate as a relay terminal. Upon receiving the relay configuration information, the corresponding terminal may recognize that the base station implicitly instructs the relay terminal to operate as a relay terminal. Alternatively, the relay configuration information may include information directly indicating that the corresponding terminal operates as a relay terminal, in addition to the parameters. Alternatively, the relay configuration information may include a threshold value for a parameter such as RSRP (Reference Signal Received Power) of a base station or Sidelink-RSRP (S-RSRP) based on a Side Link Sync Signal (SLSS) of a remote terminal in addition to the parameters . In this case, the UE can determine whether the relay terminal is operated based on the threshold value. In addition, the configuration unit 1422 can configure information on whether or not the relay terminal operation is permitted to the corresponding terminal. In this case, the terminal receiving the information on whether the relay terminal is allowed to operate can determine whether to operate the relay terminal on its own basis.

When the SL BSR MAC CE is received from the relay terminal 1300 through the RF unit 1410, the allocation unit 1423 allocates resources corresponding to the information on the amount of data included in the SL BSR MAC CE and data to be transmitted to the remote terminal The relay terminal 1300 can allocate resources corresponding to the amount of resources.

The memory 1430 may store information on the amount of data to be transmitted to the remote terminal, parameters required for the terminal to operate as a relay terminal, and the like.

Claims (10)

A method for operating a buffer state report (BSR) in a wireless communication system supporting D2D (Device to Device) communication,
The method comprising: receiving, by a first terminal located within a network coverage, data to be transmitted over a downlink from a base station to a second terminal located outside network coverage;
Triggering a BSR for data other than data to be transmitted to the second terminal among data to be transmitted through D2D communication existing in a buffer in the first terminal;
Configuring a Media Access Control (MAC) control element for the triggered BSR; And
Transmitting a MAC control element for the configured BSR to the BS
Wherein the buffer status reporting method comprises: The method according to claim 1,
And allocating resources for data to be transmitted through the D2D communication existing in the buffer in the first terminal from the base station. The method according to claim 1,
A source ID and a destination ID used in relaying communication between the base station and the second terminal, and a source ID and a destination ID used in D2D communication are configured in the first terminal. Buffer status reporting method. The method according to claim 1,
Wherein the triggering comprises:
And when the data to be transmitted through the D2D communication does not exist in the buffer in the first terminal other than the data to be transmitted to the second terminal. A relay terminal supporting D2D (Device to Device) communication in a wireless communication system,
A radio frequency (RF) unit for receiving data to be transmitted from a base station to a remote terminal located outside a network coverage through a downlink;
A controller for controlling a Buffer State Report (BSR) for data other than data to be transmitted to the remote terminal among data to be transmitted through D2D communication existing in a buffer in the relay terminal to be triggered; And
And a configuration unit (BSC) that configures a MAC (Media Access Control) control element for the triggered BSR
. 6. The method of claim 5,
The RF unit includes:
And receives information on resources corresponding to data to be transmitted through the D2D communication existing in the buffer in the relay terminal from the base station. 6. The method of claim 5,
Wherein the relay terminal comprises a source ID and a destination ID used for relaying communication between the base station and the remote terminal, and a source ID and a destination ID used for D2D communication. Terminal. 6. The method of claim 5,
Wherein,
And controls the BSR not to be triggered when there is no data to be transmitted through the D2D communication in addition to the data to be transmitted to the remote terminal in the buffer in the relay terminal. A method of operating a base station in a wireless communication system supporting D2D (Device to Device) communication,
Transmitting data for forwarding to a second terminal located outside the network coverage to a first terminal located within the network coverage via the downlink;
Receiving a Media Access Control (MAC) control element for a BSR (Buffer State Report) including information on data to be transmitted from the first terminal through D2D communication in the first terminal;
Assigning a resource corresponding to the received MAC control element and a resource corresponding to data to be transmitted to the second terminal to the first terminal;
And a base station. 1. A base station in a wireless communication system supporting D2D (Device to Device) communication,
The method comprising: transmitting data to be transmitted to a second terminal located outside the network coverage to a first terminal located in a network coverage via a downlink, and transmitting information to be transmitted through the D2D communication in the first terminal from the first terminal An RF (Radio Frequency) unit for receiving a Media Access Control (MAC) control element for a BSR (Buffer State Report); And
An allocation unit for allocating resources corresponding to the received MAC control element and resources corresponding to data to be transmitted to the second terminal to the first terminal,
/ RTI >

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