KR102312282B1 - Method and apparatus for transmitting buffer status report in wireless communication system supporting device to device communication - Google Patents

Abstract

A method and apparatus for transmitting a buffer status report in a wireless communication system supporting inter-terminal communication are provided. In a method for transmitting a buffer status report by a terminal in a wireless communication system supporting device to device (D2D) communication, a target ID, which is identification information of a target for performing the D2D communication, is mapped to a logical channel group. transmitting information on a mapping relationship between the target ID and the ID of the logical channel group to the base station using a UE Assistance Information message, and reporting a buffer status for D2D data to be transmitted to the target ( Buffer State Report) to the base station.

Description

Method and apparatus for transmitting buffer status report in a wireless communication system supporting inter-terminal communication

The present invention relates to wireless communication, and in particular, in a wireless communication system supporting device-to-device communication, a method for a terminal to transmit information on the amount of data for communication between terminals to a network through a buffer status report and devices.

Device-to-device (D2D) communication is a communication method that has been possible since the days of analog radios, and has a very long history. However, D2D communication in a wireless communication system is differentiated from existing D2D communication.

D2D communication in a wireless communication system is a communication in which terminals geographically close to each other directly exchange data in a frequency band of the wireless communication system or other bands using the transmission/reception technology of the wireless communication system without going through an infrastructure such as a base station. means This enables the terminal to use wireless communication outside of the area where the wireless communication infrastructure is built, and provides advantages of reducing the network load of the wireless communication system.

Accordingly, there is a need for a method for transmitting a buffer status report for data to be transmitted in D2D in order to efficiently provide D2D communication in a wireless communication system.

It is an object of the present invention to provide a method and apparatus for transmitting a buffer status report for data to be transmitted through inter-terminal communication in a wireless communication system supporting inter-terminal communication.

Another technical object of the present invention is to provide a method and apparatus for allocating resources for inter-terminal communication in a wireless communication system supporting inter-terminal communication.

According to an aspect of the present invention, in a method for transmitting a buffer status report by a terminal in a wireless communication system supporting device to device (D2D) communication, a target ID, which is identification information of a target for performing the D2D communication, is converted into a logical channel. Mapping to a group (Logical Channel Group), transmitting information on a mapping relationship between the target ID and the ID of the logical channel group to the base station using a UE Assistance Information message, and transmitting to the target It may include transmitting a buffer state report for the D2D data to the base station.

According to another aspect of the present invention, in a method for transmitting a buffer status report by a terminal in a wireless communication system supporting inter-terminal communication, a target ID, which is identification information of a target to perform D2D communication, is discovered through a D2D discovery procedure. Step, transmitting information on the target ID to the base station using a terminal assistance information message, RRC (Radio Resource Control) connection including information on the mapping relationship between the target ID and the ID of the logical channel group from the base station Receiving a reconfiguration message and transmitting a buffer status report for D2D data to be transmitted to a target corresponding to the target ID to the base station based on information on a mapping relationship between the target ID and the ID of the logical channel group can do.

According to another aspect of the present invention, a method for transmitting a buffer status report by a terminal in a wireless communication system supporting inter-terminal communication is a mapping between a target ID of a target allowing D2D communication within a cell of a base station and an ID of a logical channel group Receiving information on the relationship, constructing a buffer status report for D2D data existing in a logical channel group mapped to the allowed target ID, and transmitting the buffer status report to the base station. have.

According to another aspect of the present invention, a method for transmitting a buffer status report by a terminal in a wireless communication system supporting inter-terminal communication is a mapping between a target ID of a target for which D2D communication is allowed within a cell of a base station and an ID of a logical channel group Receiving information on the relationship, constructing a buffer status report for D2D data existing in a logical channel group mapped to the allowed target ID, and transmitting the buffer status report to the base station. have.

According to the present invention, for resource allocation for communication between terminals in a wireless communication system, a buffer status reporting procedure for D2D data is defined between a terminal and a base station, and when reporting a buffer status for D2D data for this purpose, operation of timers and By defining the criteria, limited radio resources can be efficiently used.

1 is a diagram illustrating a wireless communication system to which the present invention is applied.
2 is a diagram for explaining the concept of cellular network-based D2D communication applied to the present invention.
3 is a diagram illustrating a process of transmitting a ProSe-BSR according to the present invention.
4 is a diagram illustrating the structure of a MAC (Media Access Control) PDU (Protocol Data Unit) in a wireless communication system to which the present invention is applied.
5 is a diagram illustrating an example of a MAC subheader in a wireless communication system to which the present invention is applied.
6 is a diagram illustrating a buffer status report MAC control element of a wireless communication system to which the present invention is applied.
7 is a diagram illustrating a buffer status report MAC control element for communication between terminals according to an embodiment of the present invention.
8 to 11 are flowcharts illustrating a buffer status reporting procedure for D2D data according to an embodiment of the present invention.
12 is a block diagram illustrating a wireless communication system according to an embodiment of the present invention.

Hereinafter, in the present specification, contents related to the present invention will be described in detail through exemplary drawings and embodiments together with the contents of the present invention. In adding reference numerals to components in each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the embodiments of the present specification, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

In addition, this specification describes a wireless communication network, and the work performed in the wireless communication network is performed in the process of controlling the network and transmitting data in a system (eg, a base station) having jurisdiction over the wireless communication network, or the corresponding wireless communication network. An operation may be performed in a terminal included in the network.

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

Referring to FIG. 1 , a wireless communication system 10 may provide a communication service between a base station and a terminal. In a wireless communication system, a terminal and a base station may wirelessly transmit and receive data. In addition, the wireless communication system may support device-to-device (D2D) communication between the terminal and the terminal. A wireless communication system supporting D2D communication will be described later.

In the wireless communication system 10 , a base station (BS) 11 may provide a communication service to a terminal existing within the transmission coverage of the base station through a specific frequency band. The coverage serviced by the base station may also be expressed in terms of a site. A site may include a plurality of regions 15a, 15b, and 15c, which may be referred to as sectors. Each sector included in the site may be identified based on a different identifier. Each of the sectors 15a, 15b, and 15c may be interpreted as a partial area covered by the base station 11 .

The base station 11 generally refers to a station that communicates with a UE (User Equipment, 12), an evolved-NodeB (eNodeB), a Base Transceiver System (BTS), an access point (Access Point), a femto base station ( Femto eNodeB), home base station (HeNodeB: Home eNodeB), relay (relay), may be called other terms such as remote radio head (RRH: Remote Radio Head).

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

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

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

There is no limitation on the multiple access technique applied to the wireless communication system 10 . For example, Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA , OFDM-TDMA, and various multiple access schemes such as OFDM-CDMA can be used. These modulation techniques increase the capacity of the communication system by demodulating signals received from multiple users of the communication system. In addition, a Time Division Duplex (TDD) method transmitted using different times or a Frequency Division Duplex (FDD) method transmitted using different frequencies may be used for uplink transmission and downlink transmission.

The layers of the radio interface protocol between the terminal and the base station are based on the lower three layers of the Open System Interconnection (OSI) model widely known in communication systems, the first layer (L1), the second layer It may be divided into a second layer (L2) and a third layer (L3).

The physical layer belonging to the first layer provides an information transfer service using a physical channel. The physical layer is connected to a media access control (MAC) layer, which is an upper layer, through a transport channel. Data is transmitted through a transport channel between the MAC layer and the physical layer. Transport channels are classified according to how data is transmitted through the air interface. In addition, data is transmitted through a physical channel between different physical layers (ie, between the physical layers of the terminal and the base station). The physical channel may be modulated in an Orthogonal Frequency Division Multiplexing (OFDM) scheme, and uses time and frequency and a space generated by a plurality of antennas as radio resources.

For example, PDCCH (Physical Downlink Control CHannel) among physical channels informs the UE of resource allocation of PCH (Paging CHannel) and DL-SCH (DownLink Shared CHannel) and HARQ (Hybrid Automatic Repeat Request) information related to DL-SCH, An uplink scheduling grant informing the UE of resource allocation of uplink transmission may be carried. In addition, a Physical Control Format Indicator CHannel (PCFICH) informs the UE of the number of OFDM symbols used for PDCCHs, and is transmitted every subframe. In addition, a Physical Hybrid ARQ Indicator CHannel (PHICH) carries a HARQ ACK/NAK signal in response to uplink transmission. In addition, PUCCH (Physical Uplink Control CHannel) carries uplink control information such as HARQ ACK/NAK, scheduling request, and CQI for downlink transmission. In addition, a Physical Uplink Shared CHannel (PUSCH) carries an UpLink Shared CHannel (UL-SCH). When necessary according to the configuration and request of the base station, the PUSCH may include CSI (Channel State Information) information such as HARQ ACK/NACK and CQI.

The data link layer corresponding to the second layer of the OSI model includes a MAC layer, a Radio Link Control (RLC) layer, and a Packet Data Convergence Protocol (PDCP) layer.

The MAC layer performs multiplexing or demultiplexing to a transport block provided as a physical channel on a transport channel of a MAC SDU (Service Data Unit) belonging to a logical channel and a transport channel and a mapping between a logical channel and a logical channel. can do. The MAC layer provides services to the RLC layer through logical channels. The logical channel can be divided into a control channel for transmitting control domain information and a traffic channel for transmitting user domain information. For example, as services provided from the MAC layer to an upper layer, there is data transfer or radio resource allocation.

The RLC layer may perform concatenation, segmentation, and reassembly of RLC SDUs. The RLC layer has three types of transparent mode, unacknowledged mode, and acknowledged mode to ensure various QoS (Quality of Service) required by radio bearer (RB). operation mode is provided.

The PDCP layer may perform user data transfer, header compression and ciphering, and control plane data transfer and encryption/integrity protection.

The RRC (Radio Resource Control) layer belonging to the third layer of the OSI model is related to configuration, re-configuration, and release of RBs and is responsible for controlling logical channels, transport channels and physical channels. . RB means a logical path provided by the first layer (PHY layer) and the second layer (MAC layer, RLC layer, PDCP layer) for data transfer between the terminal and the network. Configuring the RB means a process of defining the characteristics of a radio protocol layer and a channel to provide a specific service, and setting each specific parameter and operation method. The RB may be divided into a signaling RB (SRB) and a data RB (DRB). The SRB is used as a path for transmitting RRC messages and NAS (Non-Access Stratum) messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane. Hereinafter, simply expressing RB without distinguishing between SRB and DRB means DRB.

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

D2D communication may refer to a technology for directly transmitting and receiving data between terminals. Hereinafter, it is assumed that the terminal supports D2D communication in an embodiment of the present invention. In addition, D2D may be replaced by an expression such as proximity based service (ProSe) or ProSe-D2D. The use of the term ProSe for D2D means that the meaning of a technology for directly transmitting and receiving data between terminals is not changed, but the meaning of a proximity-based service can be added.

Recently, a method of performing discovery and direct communication between devices in network coverage or out-of-coverage for the purpose of public safety, etc. has been proposed. is being studied. A terminal that transmits a signal based on inter-terminal communication may be defined as a transmitting terminal (Tx UE), and a terminal that receives a signal based on inter-terminal communication may be defined as a receiving terminal (Rx UE). The transmitting terminal may transmit a discovery signal, and the receiving terminal may receive the discovery signal. The roles of the transmitting terminal and the receiving terminal may be changed. Meanwhile, a signal transmitted by the transmitting terminal may be received by two or more receiving terminals.

In the cellular system, when terminals in close proximity perform D2D communication, the load of the base station may be distributed. In addition, when adjacent terminals perform D2D communication, since the terminals transmit data over a relatively short distance, consumption of transmission power and transmission latency of the terminal may be reduced. In addition, from the viewpoint of the entire system, since the existing cellular-based communication and the D2D communication use the same resource, frequency utilization efficiency can be improved.

D2D communication may be divided into a communication method of a terminal located within (in-coverage) of network coverage (base station coverage) and a communication method of a terminal located outside of network coverage (out-of-coverage).

Referring to FIG. 2 , communication between a first terminal 210 located in a first cell and a second terminal 220 located in a second cell, and a third terminal 230 located in the first cell and a first terminal located in the first cluster Communication between the 4 terminals 240 may be D2D communication within network coverage. 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. Here, the cluster head means a terminal in charge of allocating resources. The cluster header may include an independent synchronization source (ISS) for synchronization of an out-of-coverage terminal.

D2D communication may be divided into a discovery 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 may be used for public safety, ultra-low latency service, commercial purpose service, and the like. D2D communication outside of network coverage may be used only for public safety.

As an 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 transmission resources and/or reception resources that can be used for D2D communication between the first terminal 210 and another terminal (eg, the second terminal 220). .

Upon receiving the D2D resource allocation information from the base station, the first terminal 210 may 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 may perform D2D communication based on D2D resource allocation information. Specifically, the second terminal 220 may obtain information about the D2D communication resource of the first terminal 210 . The second terminal 220 may receive data transmitted from the first terminal 210 through a resource indicated by the information on the D2D communication resource of the first terminal 210 .

In D2D communication, a UE may transmit physical layer control data to another UE. However, a separate channel (eg, a physical uplink control channel (PUCCH)) for transmitting physical layer control data in D2D communication may not be defined. When a physical layer control channel is not defined in D2D communication, the UE may use various methods to transmit control data for D2D communication.

Here, physical layer control data for synchronization in D2D communication includes information transmitted through a synchronization channel, and may be provided through, for example, a Physical D2D Synchronization CHannel (PD2DSCH) channel. The physical layer control data for the data communication includes scheduling assignment (SA) information, and may be similar to a PUSCH format for D2D communication or may be provided through the same channel as the PUSCH format. And, in D2D communication, actual traffic data that is distinguished from physical layer control data may be expressed in terms of D2D data.

Additionally, a method for transmitting higher layer control data other than the physical layer in D2D communication may be defined.

During D2D communication, the terminal may operate in a first transmission mode and a second transmission mode. The first transmission mode is a mode in which the terminal can perform D2D communication only when resources for D2D communication are allocated from the base station, and the base station transmits the D2D grant to the transmitting terminal. The D2D grant includes parameter information to be determined by the base station among scheduling assignment (SA) information, which is control information to be secured for D2D data reception in the receiving terminal during D2D communication, resource allocation information for the SA, and the SA. It indicates resource allocation information for the indicated data to the transmitting terminal. The parameter information to be determined by the base station includes resource allocation information for data indicated by the SA, and the like. The D2D grant is transmitted to the transmitting terminal through downlink control information (DCI), and may be transmitted through a PDCCH or an EPDCCH. The D2D grant is control information that is used for D2D purposes through an uplink grant or a D2D-RNTI allocated to each UE. The D2D grant may be expressed as an SA/data grant.

On the other hand, the second transmission mode is a mode in which the terminal can perform D2D communication regardless of the instruction of the base station, and the terminal can transmit D2D data by internally selecting a resource to be used from among available radio resources during D2D communication. The terminal has information indicating that a specific cell in the base station can support D2D through SIB (System Information Block)/dedicated signaling and D2D resource pool information for the second transmission mode provided from the base station. Only when it exists, it can operate in the second transmission mode only for the specific cell. However, if the base station does not allow operation in the second transmission mode, that is, there is information indicating that a specific cell in the base station can support D2D, but D2D resource pool information for the second transmission mode is provided from the base station If not, it cannot operate in the second transmission mode. In addition, when D2D resource pool information for the second transmission mode is valid only in the RRC connected mode, the RRC idle (IDLE) mode UE operates in the second transmission mode even if there is D2D resource pool information for the second transmission mode. Can not. However, when the terminal is located in a non-network service area, that is, in 'Any Cell Selection' mode, which is a case in which a serviceable cell is not selected although an RRC idle mode terminal, the UICC (Universal Subscriber Identity (USIM) of the terminal) Module) The second transmission mode using D2D resource pool information for the second transmission mode stored in the Integrated Circuit Card), etc. or using the D2D resource pool information for the second transmission mode received through the base station in the previous network service area. can operate as

In a wireless communication system, the terminal reports its buffer status to the base station in order to be allocated resources necessary for transmitting uplink data (data to be transmitted to the base station) existing in the buffer in the terminal, and the base station reports the buffer status reported from the terminal. A resource to be allocated to each terminal is scheduled based on the information.

Therefore, when supporting D2D communication according to the present invention, the base station needs to schedule resources required for terminals existing in in-coverage to transmit data through D2D communication. It is necessary to know how much data (hereinafter referred to as D2D data) to be transmitted through D2D communication exists. To this end, it is intended to propose a method in which the terminal provides the base station with how much data to be transmitted through D2D communication in a buffer within the terminal.

To this end, the wireless communication system according to the present invention supports a form in which the terminal reports the buffer status of uplink data (data to be transmitted to the base station) to the base station through a buffer state report (BSR), and, An object of the present invention is to provide a form and criteria for reporting the buffer status of D2D data for efficient scheduling of resources required to transmit D2D data.

3 is a diagram illustrating a process in which a terminal transmits a ProSe-BSR to a base station in order to transmit D2D data in a first transmission mode in a wireless communication system according to the present invention.

When data to be transmitted through a D2D link exists in a DRB configured for D2D in a terminal capable of D2D communication in a wireless communication system, a buffer status report (BSR) for the D2D data is triggered (S310). Hereinafter, in the present invention, the BSR for D2D data is referred to as a ProSe-BSR. The ProSe-BSR means a BSR for D2D communication that is distinct from the BSR defined and used in the current wireless communication system.

When ProSe-BSR is triggered, the UE transmits a Scheduling Request (SR) to the base station to induce allocation of resources for transmission of D2D data and ProSe-BSR (S320), and uplink for the SR from the base station A grant (UL grant) is received (S330). Here, the SR is transmitted to the base station through the PUCCH. The SR may be used by sharing the SR used in the existing wireless communication system, or the base station may use a resource additionally allocated for the SR for D2D purpose by distinguishing it from the SR. When defining an SR for D2D use by distinguishing it from the existing SR, the SR may be defined as a ProSe-SR. For convenience of description, SR and ProSe-SR are not distinguished and are collectively referred to as SR.

When an SR is triggered, the SR is pending until canceled. On the other hand, the terminal does not accept all data pending for transmission in the uplink grant, or a MAC PDU (Media Access Control Protocol Data Unit) is configured and the MAC PDU is in a buffer state including the last event that occurred. In the case of including the configured ProSe-BSR, all pending SRs are canceled and a timer (sr-ProhibitTimer) for preventing SRs from being transmitted is stopped.

Specifically, when the SR is triggered and there is no currently pending SR, the UE sets the SR count (SR_COUNTER) value to 0. However, if the SR is pending and there is a valid PUCCH resource to send the SR in this Transmission Time Interval (TTI), this TTI is not part of the measurement gap and sr-ProhibitTimer is not in progress , if the SR_COUNTER value is less than the maximum number of SR transmissions, the SR count value is incremented by 1, and after instructing the physical layer to transmit the SR signal through the PUCCH, sr-ProhibitTimer is started. However, if the SR_COUNTER value is greater than or equal to the maximum number of transmissions, the RRC is informed of the release of PUCCH and SRS, and all configured downlink assignments and uplink grants are cleared. Then, the random access procedure is initialized and all pending SRs are canceled.

Meanwhile, when an SR is pending but there is no UL-SCH resource available for transmission in any TTI, the UE initializes a random access procedure and cancels all pending SRs. Therefore, the ProSe-BSR may be delivered to the base station through the random access procedure.

Upon receiving the uplink grant for the SR, the terminal transmits the ProSe-BSR to the base station (S340). And when receiving the D2D grant for ProSe-BSR from the base station (S350), the data is transmitted to the target terminal by using the resources allocated for D2D data transmission (S360). As such, the ProSe-BSR is for the UE to notify the serving base station of information on the amount of transmittable data present in the D2D link buffer. In the present invention, as an example, it is illustrated that the ProSe-BSR procedure is performed after SR transmission. However, if the UE receives an uplink grant sufficient to transmit ProSe-BSR before SR transmission, ProSe-BSR transmission may be performed before SR transmission.

The base station configures a periodic BSR timer (periodicBSR-Timer) and a retransmission BSR timer (retxBSR-Timer) for ProSe-BSR through signaling defined in the RRC layer, thereby proSe-BSR procedure for a logical channel in each terminal control A Logical Channel Group (LCG) may be configured in each UE through optional signaling (optionally configured by RRC signal by eNB), and the ProSe-BSR is an LCG (hereinafter referred to as LCG) including a logical channel for D2D communication. ) is carried out for The LCG is set separately from the LCG that is the target of the BSR for the wireless communication system. For example, it means that the LCG for ProSe-BSR and the LCG for the existing BSR are separately configured.

Here, the LCG, which is the target of the BSR for the wireless communication system, consists of only logical channels (DCCH, DTCH) configured for data transmission of the wireless communication system, and the index of the LC for this can be 0 to 11. have. On the other hand, the LCG, which is the target of the BSR for D2D communication, has only logical channels (PTCH) configured for the D2D data transmission, and the LC index for this is the LC index (0) for the wireless communication system. ~11), may have indices 0 to 11 of the LC for D2D communication.

In addition, the base station may additionally set a periodic timer/retransmission timer for ProSe-BSR, etc. for each terminal separately from the BSR for the wireless communication system through RRC.

The UE configures the ProSe-BSR based on the data buffered in each LCG in each UE. A maximum of four LCGs may be configured in the terminal. The format of the ProSe-BSR includes a short BSR for reporting the buffer status corresponding to one LCG, or a long BSR or truncated BSR for reporting the buffer status corresponding to four LCGs. etc. may exist. The format of the BSR will be described later.

For the ProSe-BSR procedure, the UE may consider a suspended Radio Bearer (RB) as a ProSe-BSR target, but all non-reserved RBs must be considered as a ProSe-BSR target. ProSe-BSR may be divided into regular ProSe-BSR (ProSe-BSR), Padding ProSe-BSR (ProSe-BSR), and Periodic ProSe-BSR (ProSe-BSR).

In the regular ProSe-BSR, data transmittable to the logical channel included in the LCG exists in the RLC entity or the PDCP entity, or in the uplink transmittable through a logical channel having a higher priority than other logical channels in which transmittable data already exists. Triggered when data becomes available. In addition, the regular ProSe-BSR is triggered even when the retxBSR-Timer for the ProSe-BSR expires and the UE has transmittable data in a logical channel in the LCG.

The padding ProSe-BSR is triggered when uplink resources and resources for padding BSR transmission for a wireless communication system are allocated and the number of remaining padding bits is equal to or greater than the size for ProSe-BSR transmission.

Alternatively, the padding ProSe-BSR is triggered when uplink resources and resources for BSR transmission for a wireless communication system are allocated and the number of remaining padding bits is equal to or greater than the size for ProSe-BSR transmission.

And, periodic ProSe-BSR is triggered when periodicBSR-Timer for ProSe-BSR expires.

The regular ProSe-BSR and the periodic ProSe-BSR are transmitted in a long ProSe-BSR format when more than one LCG (at least two LCGs) has data to be transmitted in the TTI in which the corresponding ProSe-BSR is transmitted, otherwise (one When only the LCG of ' has data to be transmitted), it can be transmitted in a short BSR format. The padding ProSe-BSR is equal to or greater than the combined size of the short ProSe-BSR and the short ProSe-BSR subheader in the number of padding bits included in the MAC PDU, but the long ProSe-BSR and the long ProSe-BSR subheader If more than one LCG has data to transmit in the TTI in which the corresponding ProSe-BSR is transmitted, which is smaller than the combined size, a truncated ProSe-BSR for the LCG including the logical channel having the highest priority for data transmission It may be configured and transmitted in a format. Otherwise, it is transmitted in a short ProSe-BSR format. Alternatively, when only the short ProSe-BSR format is possible, the ProSe-BSR format is always transmitted in the short ProSe-BSR format.

On the other hand, when the number of padding bits is equal to or greater than the combined size of the long ProSe-BSR and the long ProSe-BSR subheaders, the padded ProSe-BSR is transmitted in the long ProSe-BSR format. Alternatively, when only the short ProSe-BSR format is possible for the ProSe-BSR format, the short ProSe-BSR format is always transmitted.

Meanwhile, when at least one ProSe-BSR is triggered and not canceled, the UE performs the ProSe-BSR procedure. If the uplink resource for new transmission is allocated for this TTI, the UE instructs the multiplexing and assembly procedure for generation of the ProSe-BSR MAC control element, starts or restarts the periodicBSR-Timer for ProSe-BSR, and ProSe- Start or restart retxBSR-Timer for BSR. Here, the procedure of starting or restarting the periodicBSR-Timer for the ProSe-BSR is excluded when a truncated ProSe-BSR is generated. If uplink resources for new transmission are not allocated in this TTI, regular ProSe-BSR is triggered.

In this case, one MAC PDU includes only one ProSe-BSR MAC control element even if multiple ProSe-BSRs are triggered. In addition, when regular ProSe-BSR or periodic ProSe-BSR can be transmitted, it always takes precedence over padding ProSe-BSR. In addition, upon confirming reception of an indicator indicating transmission of new data for all UL-SCHs, the UE restarts the retxBSR-Timer. All triggered ProSe-BSRs shall be canceled when ProSe-BSR is included in the MAC PDU.

The UE transmits one regular or periodic ProSe-BSR in one TTI. Also, according to the present invention, the ProSe-BSR may be transmitted in the same TTI as the BSR of the wireless communication system. For example, the ProSe-BSR for the D2D service and the existing BSR for the general data service may be simultaneously transmitted in the same subframe (TTI). In this case, information classification for the corresponding BSR may be identified through the LCID.

If the UE is requested to transmit multiple MAC PDUs in one TTI, one padding ProSe-BSR may be included in arbitrary MAC PDUs that do not include regular or periodic ProSe-BSR. Accordingly, one padding ProSe-BSR may be included in any MAC PDUs including regular or periodic BSR for a wireless communication system. That is, although the padding BSR has a higher priority than the padding ProSe-BSR, the padding ProSe-BSR may be included first only in an arbitrary MAC PDU including a regular or periodic BSR. This may be included in a case where transmission of a single MAC PDU is requested in one TTI. All ProSe-BSRs always reflect the buffer state after MAC PDUs to be transmitted based on the previously received D2D grant are configured by the UE based on the TTI through which the ProSe-BSR is transmitted. Each LCG reports one buffer status value per one TTI, and the buffer status value is reported through ProSe-BSR for the LCG in all ProSe-BSRs. That is, in the same TTI, one ProSe-BSR value must be transmitted for each LCG, and the buffer status value for the LCG must be the same in all ProSe-BSRs transmitted in the same TTI. On the other hand, it is not allowed for the padding ProSe-BSR to cancel the regular or periodic ProSe-BSR. Padding ProSe-BSR is triggered for a specific MAC PDU, and triggering of the padding ProSe-BSR is canceled when a specific MAC PDU is generated. Hereinafter, the MAC PDU will be described in more detail.

4 is a diagram illustrating a structure of a MAC Protocol Data Unit (PDU) in a wireless communication system to which the present invention is applied, and FIG. 5 is a diagram illustrating an example of a MAC subheader in a wireless communication system. The MAC PDU may also be called a transport block.

4 shows, for example, a MAC header (header, 410), n MAC control elements (420-1, ..., 420-n), and m MAC SDU (Service Data Units, 430-1, ..., 430). -m) and a MAC PDU 400 including padding 440 is shown. MAC PDU 400 is a MAC header 410, 0 (zero) or at least one MAC control element (420-1, ..., 425-n), 0 or at least one MAC SDU (430-1, . ..,430-m) and padding 440 . The sizes of the MAC header 410 and the MAC SDUs 430-1, ..., 430-m may vary.

The MAC header 410 includes at least one sub-header (sub-header, 410-1, 410-2, 410-3, 410-4, ..., 410-k), and each sub-header 410- 1, 410-2, 410-3, 410-4, ..., 410-k) are MAC control elements 420-1, ..., 420-n, MAC SDUs 430-1, .., respectively. .,430-m) or padding 440 corresponds to (corresponding). The order of the subheaders 410-1, 410-2, 410-3, 410-4,..., 410-k is the corresponding MAC control element 420-1,... , 420-n), MAC SDUs 430-1, ..., 430-m, or paddings 440 are arranged in the same order.

Each subheader (410-1, 410-2, 410-3, 410-4,..., 410-k) includes 6 fields such as R, R, E, LCID, F, L, or R, It may include four fields such as R, E, and LCID. The subheader including 4 fields is a subheader corresponding to the MAC control elements 420-1, ..., 420-n or the padding 440, and the subheader including 6 fields is the MAC SDU 430. It is a subheader corresponding to -1,...,430-m).

The MAC control elements 420-1, ..., 420-n are control messages generated by the MAC layer, and are located in front of the MAC SDUs 430-1, ..., 430-m. The MAC SDUs 430-1, ..., 6430-m are the same as the RLC PDUs delivered from the RLC (Radio Link Control) layer. The padding 440 is a predetermined number of bits added so that the size of the MAC PDU 400 is constant, and is always added to the end of the MAC PDU 400 except when padding of 1 byte or 2 bytes is required. can Whatever value the padding 440 has, the terminal ignores it. The MAC control elements 420-1, ..., 420-n, the MAC SDUs 430-1, ..., 430-m, and the padding 440 are collectively referred to as a MAC payload.

For example, in FIG. 5 , the structure of a MAC subheader including six fields (R, R, E, LCID, F, L) and the structure of a MAC subheader including four fields (R, R, E, LCID) is shown. Hereinafter, fields included in the MAC subheader will be described in more detail.

The LCID (Logical Channel ID) field identifies a logical channel of a corresponding MAC SDU or identifies a corresponding MAC control element or a type of padding, and the length (size) of the LCID field may be 5 bits. . The LCID field exists one per MAC SDU, one MAC control element, or padding included in the MAC PDU. According to the present invention, a new LCID for the newly defined ProSe-BSR may be included and transmitted. This may be transmitted by including LCIDs corresponding to Tables 2 to 4 below.

The L (Length) field identifies the length of the corresponding MAC SDU or the length of a variable-sized MAC control element. The length of the L field may be indicated by the Format (F: Format) field. have. As an example, FIG. 7 shows a subheader when the length of the L field is 7 bits and 15 bits.

The F field identifies the length of the L field and may have a length of 1 bit. If the length of the MAC SDU or the 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 E (Extension) field is a flag for identifying whether other fields exist in the MAC header, and when set to "1", indicates that at least another set of R/R/E/LCID fields exists. , when set to "0", indicates that the MAC SDU, MAC control element, or padding starts at the next byte.

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

6 is a diagram illustrating a buffer status report MAC control element of a wireless communication system to which the present invention is applied.

Referring to FIG. 6 , the MAC control element (a) of a short BSR and a truncated BSR consists of one LCG ID field and one corresponding buffer size (BS) field. And, the MAC control element (b) of the long BSR consists of 4 buffer size fields corresponding to 4 LCG IDs (#0 LCG ID to #3 LCD ID). The BSR format is identified by the value of the LCID included in the subheader of the MAC PDU. LCID values for uplink are shown in Table 1 below.

Index LCID values 00000 CCCH 00001-01010 Identity of the logical channel 01011-11000 Reserved 11001 Extended Power Headroom Report 11010 Power Headroom Report 11011 C-RNTI 11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 Padding

The LCG ID field identifies a logical channel group for which the buffer status is reported to the base station, and the length of the LCD ID field is 2 bits. The buffer size field is for identifying the total amount of data available in all logical channels in the LCG after all MAC PDUs to be transmitted during one TTI are constructed. include information. Here, the RLC header and the PDCP header are not considered in calculating the buffer size. The length of the buffer size field is 6 bits. FIG. 7 is a diagram illustrating a buffer status report MAC control element for communication between terminals according to an embodiment of the present invention. Hereinafter, when the terminal transmits a buffer status report for the D2D data in the terminal, a method of notifying the base station of information on a target to which the D2D data is transmitted will be described.

A terminal supporting D2D communication may perform D2D communication when a user of the terminal configures the terminal to enable D2D communication through a user interface (UI). Alternatively, a network (eg, a D2D server that manages Proximity Services (ProSe) ID and ProSe Application ID of a terminal using D2D communication, a serving base station of the corresponding terminal, etc.) enables the user of the terminal to enable D2D communication It is also possible to finally determine whether D2D communication is possible of the terminal set to do so. That is, the terminal may perform D2D communication only when D2D communication is permitted by the network, even if D2D communication is enabled by the user of the terminal. Information on whether D2D communication is possible may be displayed on the screen of the terminal.

Resources for D2D communication may be allocated by a terminal (hereinafter, cluster head) or a base station in charge of allocating resources for D2D communication during D2D communication. In this case, the UE needs to transmit a BSR for D2D data to the base station or the cluster head when performing D2D communication. Hereinafter, for convenience of description, the base station and the cluster head are collectively referred to as a base station.

In addition, for the ProSe-BSR, an LCID different from the BSR for the existing uplink data may be used. For example, a new LCID for distinguishing a short ProSe-BSR, a truncated ProSe-BSR, and a long ProSe-BSR may be assigned to the ProSe-BSR. Alternatively, one ProSe-BSR format may be used as a BSR for D2D data.

When one ProSe-BSR format is used as a BSR for D2D data, an LCID indicating ProSe-BSR may be assigned to the BSR for the D2D data as shown in Table 2 below.

Index LCID values 00000 CCCH 00001-01010 Identity of the logical channel 01011-10111 Reserved 11000 ProSe-BSR 11001 Extended Power Headroom Report 11010 Power Headroom Report 11011 C-RNTI 11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 Padding

The base station may identify whether the received MAC control element is a BSR for uplink data or a BSR for D2D communication based on the LCID shown in Table 2. However, when the ProSe-BSR is transmitted to the base station in the form of a BSR MAC control element for uplink data as shown in FIG. 6, the base station can only know the amount of D2D data that the corresponding terminal wants to transmit, and the corresponding D2D data It is not known which terminal needs to allocate resources preferentially because it is not known about the target to transmit the . In the configuration, identification information (hereinafter, target ID) of a target to receive D2D data may be included. Hereinafter, a target ID to be described below may include one terminal for receiving D2D data, a group of terminals, or all terminals to be broadcast. The target ID may be called a ProSe ID, and the ProSe ID may be used in the first layer (physical layer) or the second layer (MAC, RLC, PDCP) of the terminal.

Referring to FIG. 7 , the ProSe-BSR may include at least one LCG ID field, a buffer size field, and a target ID field. The value of the LCG ID may have any one of 0, 1, 2, and 3 as in the existing wireless communication system. The buffer size value may also have the same value as the buffer size value in the existing wireless communication system. As an example, although ProSe-BSR configured with 16 bits is illustrated in FIG. 7 , ProSe-BSR may be configured with 24 bits including a 16-bit target ID field if necessary.

In this way, when the terminal transmits the target ID field in the ProSe-BSR, the base station may recognize that the LCG ID and the target ID included in the ProSe-BSR have a mapping relationship. In this case, information on a target to be set as each target ID may be previously stored in the base station.

On the other hand, since a maximum of 4 LCGs can be configured in the UE, when there are more than 4 target IDs, the UE cannot establish a mapping relationship between all target IDs and LCGs. Therefore, the UE can set LCs for D2D (ProSe Communication Traffic Channels) in which data to be transmitted through D2D communication exist for each combination of source ID and target ID to be mapped to one LCG. , LCs having the same source ID and target ID may be included in the same LCG, where the source ID is always fixed from the standpoint of a terminal transmitting D2D data, so the LCG may be configured according to the target ID. LCs with the same ID may not always be configured in the same LCG, that is, specific LCs may not be included in the same LCG even if the source ID and target ID are the same. can be checked and, accordingly, it can be determined whether a buffer status report for the corresponding LC is required, for example, the terminal can be used for services requiring a quick response such as voice services (Push-to-talk, etc.) or for public safety. In the case of an LC to which a service for which data transmission is required and a service that requires a lot of data transmission (video streaming service related to public safety) is mapped, it can be mapped to at least one LCG so that it can be reported to the base station through ProSe-BSR. , LCs for services for public safety are mapped to LCG = 0, and LCs for services that are not services for public safety and require quick response may be mapped to LCG = 1.

Meanwhile, as a second embodiment, when there is a target ID to which the UE is to newly transmit D2D data (eg, when there is a target ID added as a D2D data transmission target through a D2D discovery procedure, etc.) or already LCG When it is desired to change the target ID mapped to , it is possible to inform the base station of target IDs for which data is currently transmitted through D2D communication through RRC signaling.

8 to 11 are flowcharts illustrating a buffer status reporting procedure for D2D data according to an embodiment of the present invention.

First, referring to FIG. 8, when a D2D target ID is found through the D2D discovery procedure (S810), the terminal maps the target ID to the LCG (S820), and information on the mapping relationship between the target ID and the LCG ID is provided to the terminal. By transmitting to the base station using the information (UEAssistanceInformation) message, it is possible to inform the base station which target ID is mapped to which LCG (S830). For example, when a plurality of (eg, four or more) D2D target IDs are found, the terminal selects four target IDs to perform D2D communication among the target IDs, and sets the selected four target IDs to LCG, respectively. can be mapped to And, by transmitting a terminal assistance information message including information on the mapping relationship between the target ID and the LCG ID to the base station (S830), it is possible to inform the base station which target ID is mapped to which LCG. The terminal assistance information message includes a power preference indication of the terminal, and may be transmitted from the terminal to the base station after an RRC connection reconfiguration procedure. The above procedure may be started by the UE even when the UE intends to change the LCG mapping relationship with the target ID for performing D2D communication regardless of whether the UE newly discovers the D2D target ID.

In this case, since the base station already knows information about the mapping relationship between the target ID and the LCG ID through the terminal support information, when the terminal transmits a buffer status report for D2D data mapped to a specific LCG, the There is no need to transmit information about the target ID to the base station. Accordingly, the UE may transmit the ProSe-BSR using the same MAC control element format as the BSR for the existing uplink data as shown in FIG. 6 ( S840 ).

When the base station receives ProSe-BSR from the terminal, based on the LCG value included in the ProSe-BSR and information on the mapping relationship between the target ID and the LCG ID, the base station communicates with the terminals operating in another first transmission mode It is possible to determine a priority between each target ID for which a corresponding terminal has requested resource allocation in consideration of the equity, QoS, and the like, and allocate resources for D2D communication to the corresponding terminal according to the priority.

Meanwhile, referring to FIG. 9 , when a D2D target ID is found through the D2D discovery procedure ( S910 ), the terminal may transmit information on all the found target IDs to the base station using a terminal assistance information message ( S920 ). In this case, the base station may select four or less target IDs from among the target IDs received from the terminal and map the selected target IDs to the LCG, respectively. In addition, information on the mapping relationship between the target ID and the LCG ID may be informed to the UE through the RRC connection reconfiguration message. When the terminal receives the RRC connection reconfiguration message from the base station (S930), the terminal configures ProSe-BSR using the information on the mapping relationship between the target ID and the LCG ID included in the RRC connection reconfiguration message, and sets the configured ProSe-BSR to the base station. can be transmitted to (S940). The procedure may be started by the terminal when the terminal wants to exclude some of the confirmed D2D target IDs, and when the terminal wants to exclude it from the target IDs to which D2D communication is to be performed, regardless of whether or not it is discovered. That is, the target ID to be excluded is excluded from the report target.

Even in this case, since the base station already knows about the mapping relationship between the target ID and the LCG ID, the terminal provides information on the target ID mapped to the characteristic LCG when configuring a buffer status report for D2D data mapped to a specific LCG. no need to include That is, the UE may transmit the ProSe-BSR using the same MAC control element format as the BSR for the existing uplink data as shown in FIG. 6 .

In addition, as a third embodiment, the terminal may determine the priority of D2D data to be transmitted according to an application program or a service type. In this case, the base station may not need target ID information because the terminal determines the priority of the D2D data. However, the base station may compare the service characteristics of the D2D data reported by each terminal and allocate resources preferentially to the terminals having high QoS and urgency.

For example, when the D2D service is divided into a public safety service, a mobile communication voice service, a game, and a general commercial purpose service including large file transmission, the first terminal is D2D data for a public safety service. The ProSe-BSR including the indicating information may be transmitted, and the second terminal may transmit the ProSe-BSR including the information indicating that it is D2D data for a general commercial purpose service. In this case, the base station may preferentially allocate resources for D2D data for public safety services. Here, the public safety service may mean a series of protection services to prevent risks, vandalism, injuries, etc. occurring due to disasters and crimes, etc. from the national level. For public safety, organizations for police, firefighting, and disaster relief may be configured at the national level, and terminals for communication between members within each organization may be connected through different communication networks. Here, the terminal for communication between the members may be a terminal operating based on the LTE communication method.

As described above, the LCG ID may be used as information for distinguishing and indicating each service, and the LCG ID may be fixedly set for each application program or service type. For example, LCG ID = 3 may indicate a group of LCs including D2D data related to public safety, and LCG ID = 2 may indicate a group of LCs including D2D data related to general commercial service. On the other hand, the general commercial purpose service can be subdivided into a general service and an ultra-low latency service. In this case, LCG ID = 3 indicates that it is an LCG including D2D data related to public safety, and LCG ID = 2 may indicate an LCG including D2D data for a general service, and LCG ID = 1 may indicate an LCG including D2D data for an ultra-low delay service.

In this way, when the scheduler of the terminal can determine the priority of the D2D data, the priority of the D2D data may be classified according to an application program or a service type. Therefore, the UE configures a ProSe-BSR including one LCG ID indicating the highest priority based on the LCG IDs classified for each application or service, or ProSe-BSR including buffer size information for a plurality of LCG IDs. BSR can be configured (S1010). Then, the configured ProSe-BSR may be transmitted to the base station (S1020). To support this, as an example, a ProSe-BSR LCID configured as shown in Table 3 below may be used.

Index LCID values 00000 CCCH 00001-01010 Identity of the logical channel 01011-10101 Reserved 10110 Short ProSe-BSR 10111 Truncated ProSe-BSR 11000 Long ProSe-BSR 11001 Extended Power Headroom Report 11010 Power Headroom Report 11011 C-RNTI 11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 Padding

In addition, according to the fourth embodiment, the terminal may classify the priority of D2D data by using an LCID value capable of discriminating the MAC CE instead of the LCG ID according to an application program or a service type. In this case, the UE may configure ProSe-BSR having different LCID values according to the application program or service type as shown in Table 4 below.

Index LCID values 00000 CCCH 00001-01010 Identity of the logical channel 01011-10101 Reserved 10110 Ultra-low latency ProSe-BSR 10111 Normal ProSe-BSR 11000 Public safety ProSe-BSR 11001 Extended Power Headroom Report 11010 Power Headroom Report 11011 C-RNTI 11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 Padding

Meanwhile, the UE may operate in the second transmission mode (a mode in which D2D transmission is possible without receiving resource allocation from the base station) only when information on the D2D resource pool is received from the base station through SIB or dedicated signaling. However, although the base station notifies the terminal that D2D communication is possible in the corresponding cell through SIB or dedicated signaling, information on the D2D resource pool for the second transmission mode may not be provided. In this case, in order for the UE to perform D2D transmission, it must enter the RRC connected mode and operate in the first transmission mode. The terminal transmits an RRC connection request message to the base station to enter the RRC connected mode, and the RRC connection request message may include information of a D2D operation as a reason for the request. However, when the terminal is in the RRC connection state, the terminal may request D2D resource allocation from the base station through SR and ProSe-BSR. In this case, as a fifth embodiment, the base station performs D2D communication among all target IDs in the cell. Four or less target IDs for the allowed group (or terminal) may be designated (S1110). The reason for specifying 4 or less target IDs is that a maximum of 4 LCG IDs can be set in the terminal, and the reason that the base station allows only D2D communication of a specific group (or terminal) is to perform D2D communication for public safety. If there is a group (or terminal) and a group (or terminal) that wants to perform D2D communication for other purposes (for example, commercial purposes), only D2D communication with high public safety and priority may be allowed at a specific time. because it may be necessary. To this end, the base station maps the designated target ID to each LCG ID (S1120), and provides information on the mapping relationship between the target ID and the LCG ID through SIB or dedicated signaling (eg, RRC connection reconfiguration message) within the cell. It can be transmitted to the terminals (S1130). As an example, the base station may allocate LCG ID = 0 to the target ID for the purpose of broadcasting, and the other LCG IDs (1,2,3) may be allocated to target IDs corresponding to specific groups, respectively. Accordingly, all of the terminals existing in the cell of the base station may have the same mapping relationship between the target ID and the LCG ID.

When the terminal receives information on the mapping relationship between the target ID and the LCG ID of a target for which D2D communication is allowed in the cell of the base station, the buffer status report is configured only for the D2D data present in the LCG mapped to the allowed target ID. can That is, all terminals in the cell can perform the ProSe-BSR procedure only for the target ID allowed by the base station, and the base station can receive only the ProSe-BSR including the LCG ID mapped to the allowed target ID ( S1140). In this case, the ProSe-BSR may have a new LCID value for ProSe-BSR as shown in Table 3 according to its format. Alternatively, as shown in Table 2, only a single format (eg, only short) having a single LCID value for ProSe-BSR may be used.

12 is a block diagram illustrating a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 12 , the wireless communication system supporting inter-terminal communication according to the present invention includes a terminal 1200 and a base station (or cluster head, 1250 ).

The terminal 1200 includes a processor 1205 , a radio frequency (RF) unit 1210 , and a memory 1215 . The memory 1215 is connected to the processor 1205 and stores various information for driving the processor 1205 . The RF unit 1210 is connected to the processor 1205 to transmit and/or receive a radio signal. For example, the RF unit 1210 may receive the RRC connection reconfiguration message and the SIB posted herein to the base station 1250 . In addition, the RF unit 1210 may transmit the uplink signal posted herein to the base station 1250 .

The processor 1205 implements the functions, processes and/or methods proposed herein. Specifically, the processor 1205 causes all steps according to FIGS. 8 to 10 to be performed.

For example, the processor 1205 may include a target ID determination unit 1206 , an LCG mapping unit 1207 , and a ProSe-BSR configuration unit 1208 . In this case, when the D2D target ID is found through the D2D discovery procedure, the target ID determiner 1206 may determine whether to map the target ID to the LCG. In addition, it may be determined whether the mapping relationship between the target ID and the LCG is changed. The LCG mapping unit 1207 maps the target ID determined to be mapped to the LCG by the target ID determining unit 1206 to the corresponding LCG. Information on the mapping relationship between the target ID and the LCG ID generated by the LCG mapping unit 1207 may be transmitted by the RF unit 1210 to the base station 1250 using a UEAssistanceInformation message, and the base station 1250 ) can know which target ID is mapped to which LCG based on this. Meanwhile, when data to be transmitted through the D2D link exists in the DRB configured for D2D, the ProSe-BSR configuration unit 1208 may configure the ProSe-BSR in the form of the MAC control element shown in FIG. 6 or 7 . . The configured ProSe-BSR MCA control element may be transmitted to the base station 1250 by the RF unit 1210 .

Meanwhile, as another example, the processor 1205 may include a target ID determination unit 1206 and a ProSe-BSR configuration unit 1208 . In this case, if the D2D target ID is found by the target ID determiner 1206 or the mapping relationship between the target ID and the LCG needs to be changed, the RF unit 1210 transmits information about the corresponding target ID using a terminal support information message. can be transmitted to the base station. In this case, the RF unit 1210 may receive information on the mapping relationship between the target ID and the LCG ID from the base station 1250 through the RRC connection reconfiguration message. In addition, the ProSe-BSR configuration unit 1208 may configure the ProSe BSR by using the information on the mapping relationship between the target ID and the LCG ID included in the RRC connection reconfiguration message.

As another example, the processor 1205 may determine the priority of D2D data to be transmitted according to an application program or a service type. In this case, the ProSe-BSR configuration unit 1208 of the processor 1205 configures a ProSe BSR including one LCG ID indicating the highest priority based on the LCG ID classified for each application or service, or A ProSe BSR including buffer size information for LCG IDs can be configured. Alternatively, ProSe BSRs having different LCID values may be configured for each application or service type. This can configure the ProSe BSR with the LCID values differentiated as shown in Tables 2 to 4.

As described above, in all embodiments of the present specification, the operation of the terminal 1200 may be implemented by the processor 1205 .

The memory 1215 stores information on the mapping relationship between the target ID and the LCG ID or information on the priority between D2D data according to the present specification, and provides the target ID and the LCG to the processor 1205 according to the request of the processor 1205 . Information on a mapping relationship between IDs or information on a priority between D2D data may be provided.

The base station 1250 includes an RF unit (radio frequency (RF) unit, 1255 ), a processor 1260 , and a memory 1265 . The memory 1265 is connected to the processor 1260 and stores various information for driving the processor 1260 . The RF unit 1255 is connected to the processor 1260 to transmit and/or receive a radio signal. The processor 1260 implements the functions, processes and/or methods proposed herein. In the above-described embodiment, the operation of the base station 1250 may be implemented by the processor 1260 . The processor 1260 generates the RRC connection reconfiguration message posted herein, and schedules a resource for D2D communication based on information on a mapping relationship between a target ID and an LCG ID.

For example, the processor 1260 may include an LCG mapping unit 1261 , a ProSe-BSR verification unit 1262 , and a D2D resource allocator 1263 . In this case, the LCG mapping unit 1261 based on the information (information on the mapping relationship between the target ID and the LCG ID) included in the terminal support information message received from the terminal 1200 through the RF unit 1255, the target IDs can be mapped to LCG IDs. When the ProSe-BSR is received from the terminal 1200 , the ProSe-BSR check unit 1262 may check the LCG value included in the ProSe-BSR. The D2D resource allocator 1263 determines the priority of the terminal 1200 in consideration of equity and QoS with terminals operating in another first transmission mode based on the information on the mapping relationship between the target ID and the LCG ID. ) to allocate resources for D2D communication.

Meanwhile, in another embodiment, when a plurality of target IDs are received from the terminal 1200 , the LCG mapping unit 1261 selects four or less target IDs from among the received target IDs and maps the selected target IDs to the LCG, respectively. can do. In addition, information on the mapping relationship between the target ID and the LCG ID may be informed to the terminal 1200 through the RRC connection reconfiguration message.

The processor may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and/or data processing devices. 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 a radio signal. When the present embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) that performs the above-described function. A module may be stored in a memory and executed by a processor. The memory may be internal or external to the processor, and may be coupled to the processor by various well-known means.

In the exemplary system described above, the methods are described on the basis of a flowchart as a series of steps or blocks, however, the present invention is not limited to the order of steps, and some steps may occur in a different order or concurrent with other steps as described above. can In addition, those skilled in the art will understand that the steps shown in the flowchart are not exhaustive 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 present invention.

The above-described embodiments include examples of various aspects. It is not possible to describe every possible combination for representing the various aspects, but one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the present invention cover all other substitutions, modifications and variations falling within the scope of the following claims.

Claims (16)

A communication method comprising:
receiving, by a first wireless user equipment, configuration information from a base station, the configuration information relating to direct data communication from the first wireless user equipment to one or a plurality of wireless user equipments;
Here, the configuration information includes resource selection mode information for direct data communication, and the resource selection mode information indicates a resource pool, wherein one or a plurality of the first wireless UEs are selected from the resource pool. selecting a resource for direct data communication to wireless user devices;
mapping a first target ID (identity) to a first group ID;
mapping a second target ID to a second group ID;
the first target ID is associated with at least one target wireless user device of a first group of target wireless user devices, the second target ID is associated with at least one target wireless user device of a second group of target wireless user devices, and ,
transmitting a radio resource control (RRC) message including the first target ID information and the second target ID information to the base station; and
Transmitting a media access control-layer (MAC-layer) message related to the first group ID and the second group ID to the base station;
The MAC-layer message includes a first field and a second field, wherein the first field indicates the first group ID and the first target ID, and the second field includes the second group ID and the second field. 2 A communication method indicating a target ID.
According to claim 1,
Including; transmitting another message including the changed mapping information to the base station;
and the changed mapping information is mapping information between the first group ID and a third target ID associated with at least one target wireless user device of a third group of target wireless user devices.
3. The method of claim 2,
The other message is related to resource scheduling by the base station,
wherein the resource scheduling indicates a resource for direct data communication of the first wireless user equipment.
According to claim 1,
The first target ID is configured to be identified by a proximity service layer-2 ID (Proximity service layer-2 ID, ProSe layer-2 ID),
The ProSe layer-2 ID related to ProSe layer-2 includes a MAC layer, a radio link control layer (radio link control layer, RLC layer) and a packet data convergence protocol layer (PDCP protocol layer), communication method.
According to claim 1,
wherein the first group of target wireless user devices comprises one or a plurality of first target wireless user devices that receive direct data transmitted from the first wireless user device.
According to claim 1,
The MAC-layer message includes a buffer status report (BSR) related to one or a plurality of target IDs,
wherein the one or plurality of target IDs include the first target ID and the second target ID.
According to claim 1,
Including; receiving a system information block (SIB) message from the base station;
The SIB message includes information supporting direct data communication of the first wireless user equipment.
8. The method of claim 7,
The information supporting direct data communication of the first wireless user equipment indicates whether a specific cell supports direct data communication, and
and the particular cell is associated with a frequency band in which the first wireless user equipment transmits data directly to one or a plurality of wireless user equipments.
A first wireless user device comprising:
a wireless transceiver for receiving configuration information from a base station; wherein the configuration information relates to direct data communication from the first wireless user device to one or a plurality of wireless user devices;
The configuration information includes resource selection mode information for direct data communication, and the resource selection mode information indicates a resource pool, wherein the first wireless user equipment is selected from one or a plurality of wireless users from the resource pool. selecting a resource for direct data communication to devices;
a processor configured to map a first target identity to a first group ID and a second target ID to a second group ID;
wherein the first target ID is associated with at least one target wireless user device of a first group of target wireless user devices;
the second target ID is associated with at least one or more target wireless user devices of a second group of target wireless user devices;
The radio transceiver transmits a radio resource control (RRC) message to the base station, wherein the RRC message includes the first target ID information and the second target ID information,
The wireless transceiver transmits a media access control layer (MAC-layer) message related to the first group ID and the second group ID to the base station, and the MAC-layer message includes a first field and a first An apparatus comprising two fields, wherein the first field comprises the first group ID and the first target ID, and the second field comprises the second group ID and the second target ID.
10. The method of claim 9,
The wireless transceiver sends another message to the base station including the changed mapping information, wherein the changed mapping information is a third associated with the first group ID and at least one target wireless user equipment of a third group of target wireless user equipments. Device, which is mapping information between target IDs.
11. The method of claim 10,
The other message is related to resource scheduling by the base station,
wherein the resource scheduling indicates a resource for direct data transmission of the first wireless user equipment.
10. The method of claim 9,
The first target ID is configured to be identified by a proximity service layer-2 ID (Proximity service layer-2 ID, ProSe layer-2 ID),
The ProSe layer-2 ID related to ProSe layer-2 includes a MAC layer, a radio link control layer (radio link control layer, RLC layer), and a packet data convergence protocol layer (PDCP layer). ,
10. The method of claim 9,
wherein the first group of target wireless user devices comprises one or a plurality of first target wireless user devices that receive direct data transmitted from the first wireless user device.
10. The method of claim 9,
The MAC-layer message includes a buffer status report (BSR) related to one or a plurality of target IDs,
wherein the one or more target IDs include the first target ID and the second target ID.
10. The method of claim 9,
The wireless transceiver receives a system information block (SIB) message from the base station,
The SIB message includes information supporting direct data transmission of the first wireless user equipment.
16. The method of claim 15,
The information supporting direct data communication of the first wireless user equipment indicates whether a specific cell supports direct data communication, and
and the particular cell is associated with a frequency band through which the first wireless user equipment transmits data directly to one or a plurality of wireless user equipments.

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