WO2015152621A1

WO2015152621A1 - Method and apparatus for transmitting data in device-to-device communication

Info

Publication number: WO2015152621A1
Application number: PCT/KR2015/003218
Authority: WO
Inventors: 장재혁; 정경인; 김상범; 김성훈
Original assignee: 삼성전자 주식회사
Priority date: 2014-03-31
Filing date: 2015-03-31
Publication date: 2015-10-08
Also published as: KR102099642B1; KR20150113777A

Abstract

The present invention relates to a device-to-device (hereinafter D2D) communication method in a wireless communication system. The D2D communication method of a terminal according to the present invention comprises the steps of: attempting a connection to a base station in order to request a resource for performing a D2D communication; when the connection attempt fails, selecting, on the basis of resource allocation information for a preset D2D terminal, a resource for performing the D2D communication; and performing a D2D communication using the selected resource.

Description

Method and apparatus for transmitting data in terminal to terminal communication

The present invention relates to a wireless communication system, and more particularly, to a 3GPP (The 3rd Generation Partnership Project) system (e.g., a Long Term Evolution (LTE) system, etc.) device-to-device, Hereinafter, referred to as D2D), the present invention relates to a method for transmitting data.

Recently, wireless communication technology has made rapid progress, and communication system technology has evolved accordingly. Among them, 3GPP UMTS (Universal Mobile Telecommunications System) system is the representative third generation mobile communication technology. The spotlight system is LTE system.

1 is a diagram showing the structure of the LTE system to which the present invention is applied.

Referring to FIG. 1, as illustrated, a radio access network of an LTE system includes a next-generation base station (Evolved Node B, ENB, Node B, or base station) 105, 110, 115, and 120 and an MME 145 (Mobility Management Entity). And S-GW 130 (Serving-Gateway). The user equipment (hereinafter referred to as UE or terminal) 135 accesses an external network through the ENBs 105 to 120 and the S-GW 130.

In FIG. 1, the ENBs 105 to 120 correspond to existing Node Bs of the UMTS system. The ENB is connected to the UE 135 by a radio channel and performs a more complicated role than the existing Node B. In LTE system, all user traffic, including real-time services such as Voice over IP (VoIP) over the Internet protocol, is serviced through a shared channel, so information on the status of buffers, available transmit power, and channel status of UEs is available. It is necessary to have a device for scheduling the collection of this, ENB (105 ~ 120) is in charge. One ENB typically controls multiple cells. For example, in order to realize a transmission rate of 100 Mbps, the LTE system uses orthogonal frequency division multiplexing (hereinafter, referred to as OFDM) in a 20 MHz bandwidth as a radio access technology. In addition, an adaptive modulation & coding (AMC) scheme that determines a modulation scheme and a channel coding rate according to the channel state of the terminal is applied. The S-GW 130 is a device for providing a data bearer, and generates or removes a data bearer under the control of the MME 145. The MME is a device that is in charge of various control functions as well as mobility management function for the terminal and is connected to a plurality of base stations.

2 is a diagram illustrating a radio protocol structure in the LTE system to which the present invention is applied.

Referring to FIG. 2, a wireless protocol of an LTE system includes packet data convergence protocols 205 and 240 (PDCP), radio link control 210 and 235 (RMC), and medium access control 215 and 230 (MAC) in a terminal and an ENB, respectively. The PDCP (Packet Data Convergence Protocol) 205, 240 is responsible for operations such as IP header compression / restore, and the radio link control (hereinafter referred to as RLC) 210, 235 is a PDCP PDU (Packet Data Unit). ) To the appropriate size. The

MACs

215 and 230 are connected to several RLC layer devices configured in one terminal, and multiplex RLC PDUs to MAC PDUs and demultiplex RLC PDUs from MAC PDUs. The

physical layers

220 and 225 channel-code and modulate higher layer data, make an OFDM symbol, and transmit it to a wireless channel, or demodulate, channel decode, and transmit the received OFDM symbol through a wireless channel to a higher layer. . In addition, the physical layer uses HARQ (Hybrid ARQ) for additional error correction, and the receiving end transmits the reception of the packet transmitted by the transmitting end as 1 bit. This is called HARQ ACK / NACK information. Downlink HARQ ACK / NACK information for uplink transmission is transmitted through PHICH (Physical Hybrid-ARQ Indicator Channel) physical channel, and uplink HARQ ACK / NACK information for downlink transmission is PUCCH (Physical Uplink Control Channel) or PUSCH. (Physical Uplink Shared Channel) It may be transmitted through a physical channel.

Currently, data usage of users has exploded with the spread of smart phones, and mobile network operators are providing data services to subscribers by installing the latest LTE system to handle explosive data. However, the demand for data transmission is still increasing, and there is a need for developing new technologies. Accordingly, the 3GPP standards organization is trying to define a technology for communication between the terminal and the terminal (Device-to-Device, hereinafter referred to as D2D) without passing through the base station.

On the other hand, even during the D2D communication, the radio resource is used by sharing the radio resource used between the existing base station and the terminal. Thus, there are two ways to avoid this.

The first method is a method for requesting allocation of resources to a base station for data transmission in D2D communication (hereinafter, this method is referred to as 'first method for transmitting D2D'). In other words, the base station centrally receives requests for all radio resources and allocates all resources to the base station. Therefore, the present method is a method that can be utilized when the terminal is in the signal of the base station, that is, the coverage of the base station.

3 is an exemplary sequence diagram thereof. In FIG. 3, terminal 1 301 generates data to be sent to terminal 2 303 (311). In the present example, as described above, the terminal 1 is allocated a resource for transmitting data to the terminal 2 from the base station 305. Accordingly, a request for resource allocation for D2D communication is performed to the base station. If a resource that can be transmitted to the base station is not previously allocated, the terminal 1 performs a random access procedure to the base station (313), and requests the resource for communication with the terminal 2 as the allocated resource through this (315). The above case is an operation when the terminal operates in a radio resource control (RRC_IDLE) dormant state (RRC_IDLE) that is not connected to the base station. Or, if the RRC connection state (RRC_CONNECTED) is connected to the base station and the resources to send to the base station is allocated, the base station immediately requests resources for communication with the terminal 2 (315).

In this case, the RRC_IDLE state may mean a state in which a terminal is not established to establish a connection between a base station and a radio resource control (RRC) layer. In this state, the terminal and the base station may not be able to transmit and receive unicast data with each other.

Meanwhile, the RRC_CONNECTED state may mean a state in which a terminal attempts to access a base station and establishes a connection with an RRC layer. In this state, the terminal and the base station may be capable of transmitting and receiving unicast data with each other.

Meanwhile, as a method for requesting the resource, a method for reporting the amount of data to be sent that is stored in the current buffer (buffer) may be used (buffer status report, buffer status report), which is implemented in all embodiments of the present invention. In the example, it is applicable. The base station receives the resource for the D2D communication from the received base station (317), and the terminal 1 can transmit and receive data with the terminal 2 exclusively from the allocated resource from the base station (319).

The second method is a method of acquiring D2D UEs by competing resources determined for D2D communication for data transmission during D2D communication (hereinafter, referred to as 'the second method of D2D transmission'). That is, whether or not the utilization of radio resources is distributed to each D2D user equipment without a central device such as a base station. Unlike the first method of D2D transmission, the present method does not have a device that is the center of resource allocation, and thus may collide with each other during data transmission, but the device structure is simple. Therefore, the present scheme is a method that can be utilized when the terminal is out of coverage of the base station, that is, the signal of the base station.

4 is an exemplary sequence diagram thereof. In FIG. 4, terminal 1 401 generates data to be sent to terminal 2 403 (411). Subsequently, the terminal acquires radio resources by performing a radio resource acquisition competition with other D2D terminals within resources allocated for D2D communication, except for resources allocated for communication with the base station and the terminals, among all radio resources. (413), and transmits data to the obtained resource (415). As a method of the contention competing, a method of detecting whether the current channel is empty and if it is determined that the channel is empty may be used.

On the other hand, when the base station accesses too many users in the cell, the access class barring (hereinafter referred to as "ACB") technique, by using the technique can block the access of the terminal in the cell that wants to access the base station. In the ACB scheme, a base station broadcasts accessibility information to terminals in a cell, and generates a random number when the terminal attempts to access the connection so that the access is blocked when the random number is greater than the accessibility information. That's how.

On the other hand, when the ACB scheme and the first D2D transmission scheme are used at the same time, the terminal is disconnected even though the terminal attempts to access the resources of the D2D communication so that the D2D communication cannot be performed. One way is needed.

The present invention was devised to solve the above problems, and an object of the present invention is to block access of a base station when performing D2D communication in a cellular network (for example, 4G network such as LTE) in a wireless communication system. In this case, a method for performing D2D communication is provided.

In a device-to-device (D2D) communication method of a terminal of the present invention for solving the above problems, attempting to access a base station to request a resource for performing the D2D communication, the connection attempt fails And selecting a resource for performing the D2D communication based on resource allocation information for a preset D2D terminal, and performing D2D communication using the selected resource.

In addition, a terminal performing a device to device (D2D) of the present invention for solving the above problems is a communication unit for transmitting and receiving a signal with another network entity, to request a resource for performing the D2D communication Attempting to access a base station, selecting a resource for performing the D2D communication based on resource allocation information for a preset D2D terminal when the access attempt fails, and performing a D2D communication using the selected resource Characterized in that.

Using the proposed method, the terminal can perform terminal-to-terminal data communication even in a situation where the access of the base station is blocked.

1 is a diagram illustrating a structure of an LTE system to which the present invention is applied.

2 is a view showing a radio protocol structure in an LTE system to which the present invention is applied

3 illustrates an example of requesting allocation of resources to a base station for data transmission during D2D communication;

4 illustrates an example of a method of obtaining resources determined for D2D communication by competition between D2D terminals for data transmission during D2D communication;

5 is an exemplary message flow diagram applying D1D data transmission method according to the first embodiment of the present invention.

6 is a diagram illustrating an operation sequence of a terminal to which the first embodiment of the method for transmitting D2D data proposed in the present invention is applied.

7 is a diagram illustrating an example of a message flow to which the second embodiment of the method for transmitting D2D data proposed in the present invention is applied.

8 is a diagram illustrating an operation sequence of a terminal to which the second embodiment of the method for transmitting D2D data proposed in the present invention is applied.

9 is an exemplary message flow diagram applying D3D data transmission method Example 3 proposed in the present invention.

10 is a diagram illustrating an operation sequence of a terminal to which the third embodiment of the method of transmitting D2D data proposed in the present invention is applied.

11 is an exemplary message flow diagram applying D4D data transmission method according to the fourth embodiment of the present invention.

12 is a diagram illustrating an operation sequence of a terminal to which the fourth embodiment of the method for transmitting D2D data proposed in the present invention is applied.

13 is a diagram illustrating a configuration of a terminal according to an embodiment of the present invention.

14 is a diagram illustrating a configuration of a base station according to an embodiment of the present invention.

In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the present invention, for convenience of description, an example of a cellular network will be described based on an LTE system, but may be applied to other cellular networks (for example, UMTS).

5 is a diagram illustrating an example of a message flow to which the first embodiment of the method for transmitting D2D data proposed in the present invention is applied.

In this example, UE 1 501 is in the above-described RRC dormant state, and assumes a situation in which UE 2 503 directly transmits data using D2D communication. In addition, it is assumed that the terminal 1 is located within the coverage of the base station 505 to allocate resource for D2D communication from the base station, that is, to use the above-described first method of transmitting D2D.

Data to be transmitted to the terminal 1 (501) in the sleep mode is generated (511). For example, it may be caused by making a phone call, sending a picture, a file, or the like.

The terminal 1 may receive the above-described existing ACB parameter from the base station 505 before or after data to be transmitted is generated (513). Depending on the base station, the ACB parameter may not be transmitted.

If the ACB parameter is transmitted from the base station 505, the terminal 1 determines whether the access is blocked by the aforementioned method (515). That is, when the base station broadcasts the accessibility probability information and the access blocking time (ACB parameter) to the terminals in the cell, and the terminal generates a random number when the access attempt, the random number is larger than the accessibility probability information The UE determines that the access to the base station is blocked by the access interruption time. In the present invention, as an example when the terminal determines that the connection is blocked, the terminal may determine whether the connection to the base station is blocked after performing the accessibility probability information once, or a predetermined number of times, Alternatively, even when blocked for a predetermined time, it can be determined that the connection to the base station is blocked. The predetermined number of times or a predetermined time may be transmitted by the base station together with the ACB parameter, or a value determined by the standard may be used.

If it is determined that the access to the base station is blocked, the terminal determines whether the data to be transmitted is the data to be transmitted to the base station or whether the data is generated due to the generation of data for the D2D communication or the start of the service (517).

If the data to be sent is data to be transmitted to the base station, the terminal blocks data transmission to the base station during the access cutoff time.

However, if the data to be sent is data for D2D communication, even though the terminal 1 is currently located in the coverage of the base station, the terminal does not make a resource request to the base station to transmit data, and transmits the D2D data. The radio resources for the radio network are selected by themselves (519) (521) and D2D data transmission is performed (523). As a method of selecting a radio resource to be transmitted by itself, a method of detecting whether there is another terminal currently using radio resources (carrier sensing), or resource allocation information for D2D terminals transmitted by a D2D terminal or transmitted by a base station (D2D scheduling assignment information) and the like may be utilized.

Even when the terminal uses the method of selecting the radio resource to be transmitted by itself, in the scenario where the terminal changes the ACB parameter transmitted by the base station, or the system information that the base station broadcasts to inform the terminals in the cell is changed. In addition, it may determine whether to disconnect again, perform random access to the base station and attempt data transmission.

In addition, when the terminal performs the random access procedure for resource request for D2D data transmission to the base station, a random access procedure may fail or be delayed. For example, the terminal may fail to succeed in the random access procedure because many terminals simultaneously perform random access, or may receive a command from the base station to perform the access later due to the large number of terminals connected. Even when the random access procedure fails or the connection is delayed as described above, the terminal may determine whether the data to be sent is D2D data and select a radio resource to transmit by itself.

Meanwhile, in the above example, a method of determining whether the terminal determines whether to block access first and then determines the type of data (that is, whether the data is transmitted to the base station or the data to be transmitted to the D2D) has been described as an example. Can be. That is, after determining the type of data first, it is possible to determine whether to block the access. If the data type is D2D data, the terminal does not determine whether to block the access and directly selects a radio resource for the D2D data transmission. Can be used.

Data to be transmitted to the terminal in the sleep mode is generated (601). For example, data to be transmitted to the terminal may occur due to a phone call, a picture, a file, or the like.

The UE determines whether there is an ACB parameter received from the base station before or after generating data to be transmitted (603). If there is no ACB parameter, the UE performs a random access procedure to the base station (621) and transmits data to the base station. And transmit (623).

However, if there is an ACB parameter received from the base station, the terminal determines whether the connection is blocked using the above-described method (605). As described with reference to FIG. 5, the terminal may determine whether to disconnect the access after performing the accessibility probability information comparison once, or may determine that the access is blocked even if the access is blocked for a predetermined number of times or for a predetermined time. Can be. The predetermined number of times or the predetermined time may be received from the base station together with the ACB parameter, or a fixed value defined in the standard may be used. If the terminal determines that the access is not blocked, the terminal may perform a random access procedure to the corresponding base station (621) and transmit data to the base station (623).

However, if it is determined that the access is blocked, the terminal determines whether the data to be sent is data to be transmitted to the base station or data for D2D communication (607).

If the data to be sent is data to be transmitted to the base station, the terminal blocks the data transmission for the access disconnection time and ends (631).

However, if the data to be sent is data for D2D communication, the UE selects a radio resource for D2D data transmission by itself (609) and performs D2D data transmission (611). As a method of selecting a radio resource to be transmitted by itself, a method of detecting whether there is another terminal currently using radio resources (carrier sensing), or resource allocation information for D2D terminals transmitted by a D2D terminal or transmitted by a base station (D2D scheduling assignment information) and the like may be utilized.

7 is a diagram illustrating an example of a message flow to which the second embodiment of the D2D data transmission method proposed in the present invention is applied.

In the exemplary drawing, terminal 1 701 is in the above-described RRC dormant state, and assumes a situation in which data is directly sent to terminal 2 703 using D2D communication. In addition, it is assumed that the terminal 1 is located in the coverage of the base station 705 to allocate resource for D2D communication from the base station, that is, to use the above-described first D2D transmission scheme.

Data to be transmitted to the terminal 1 (701) in the sleep mode is generated (711). For example, the data to be transmitted may occur due to a phone call, a picture, a file, or the like.

The terminal 1 may receive the above-described existing ACB parameter and the ACB parameter for D2D communication proposed by the present invention from the base station 705 before or after generation of data to be transmitted (713). Depending on the base station, the ACB parameter may not be transmitted.

If the ACB parameter is present, the terminal determines whether data to be transmitted is data to be transmitted to the base station or data for D2D communication (715).

If the current data to be transmitted is the data to be transmitted to the base station, the terminal determines whether to disconnect the access using the existing ACB parameters.

If the current data to be transmitted is data for D2D communication, the UE determines whether to block access using the ACB parameter for D2D communication proposed in the present invention (717). Accordingly, if the access is not blocked, the terminal performs a random access procedure to the base station (719). If the random access procedure is successful, the terminal 1 requests a radio resource for communication with the terminal 2 to the base station (721). Thereafter, when the radio resource for communication with the terminal 2 is allocated from the base station (723), the terminal 1 transmits data to the terminal 2 using the allocated resource (725).

In the above example, an example in which an ACB parameter for D2D is separately described has been described, but other forms of embodiments may also exist. In a further embodiment, for example, the base station may transmit, in addition to the existing ACB parameter, an indicator indicating that it is not necessary to check whether to block for D2D communication, instead of the proposed ACB parameter for D2D communication. . If the indicator is transmitted, the terminal may immediately perform random access without determining whether to block access (717).

In addition, as an additional embodiment, even when using only the existing ACB parameters, when the terminal uses D2D communication for the purpose of public safety, the terminal may change the current connection type, thereby avoiding the connection blocking procedure. have. To this end, the terminal does not use an access class (AC) number between 0 and 9 that is uniquely assigned to the terminal used to transmit normal data, and is allocated between 10 and 15 times allocated for a separate purpose. You can use the number of.

In addition, the second embodiment and the first embodiment may be used simultaneously. For example, if the terminal performs the random access procedure by determining that the access is not blocked through the above method, but fails or is delayed, the terminal determines whether the data is D2D data, and the method described in the first embodiment is described. As described above, a method of selecting radio resources to transmit by itself may be used.

Data to be transmitted to the terminal in the sleep mode is generated (801). For example, the data to be transmitted may occur due to a phone call, a picture, a file, or the like.

The terminal determines whether there is an ACB parameter received from the base station before or after generation of data to be transmitted (803).

If there is no received ACB parameter, the terminal performs a random access procedure to the base station (821), and can transmit data to the base station (823).

If the received ACB parameter exists, the terminal determines whether the data to be transmitted is data to be transmitted to the base station or data for D2D communication (S805).

If the current data to be transmitted is the data transmitted to the base station, the terminal determines whether to disconnect the access using the existing ACB parameters (807), if the connection is blocked (809), the terminal is disconnected for the corresponding time. Blocking and terminating (831), if the connection is not blocked (809), the UE performs a random access procedure to the base station (821), and transmits data to the base station (823).

If the current data to be transmitted is data for D2D communication, the terminal determines whether the connection is blocked using the ACB parameter for D2D communication proposed in the present invention (811), and if the connection is blocked (813), The terminal blocks and terminates the access for the corresponding time (831). If the access is not blocked (811), the UE performs a random access procedure to the corresponding base station (825) and performs a random access procedure to the base station to perform D2D. Request radio resources for communication. Thereafter, when the radio resource for D2D communication is allocated from the base station, the terminal transmits data to the allocated resource (827).

9 is a diagram illustrating an example of a message flow to which the third embodiment of the D2D data transmission method proposed in the present invention is applied.

In this example, UE 1 901 is in the above-described RRC dormant state and assumes a situation in which UE 2 903 directly sends data to UE 2 903 using D2D communication. In addition, it is assumed that the terminal 1 is located within the coverage of the base station 905 to use resource allocation for the D2D communication from the base station, that is, the above-described first method of transmitting D2D.

Data to be transmitted to the terminal 1 (901) in the sleep mode is generated (911). For example, the data to be transmitted may occur due to a phone call, a picture, a file, or the like.

The terminal 1 may receive the aforementioned ACB parameter from the base station 905 before or after generation of data to be transmitted (913).

If the ACB parameter is received, the terminal determines whether connection is blocked as described above (915). If it is determined that access to the base station is blocked, the terminal 1 excludes the base station from the cell (re) selection for a predetermined time or until a predetermined event occurs for the base station (917). In addition, terminal 1 performs a cell selection or cell reselection procedure to select another cell (919).

The predetermined time may be transmitted by the base station together with the ACB parameter, or may use a fixed value defined in the standard. In addition, the predetermined event may be, for example, when data to be sent to the base station occurs. In addition, the cell selection or cell reselection procedure follows the contents of the 3GPP TS 36.304 standard.

Thereafter, the terminal 1 selects a new cell or base station (base station 2 907 in the present example). The base station 2 may be a base station operating at the same frequency as the base station 1 or at a different frequency. If the selected base station transmits the ACB parameter (921), the terminal determines whether the access to the base station is blocked (923). If the access is not blocked, the terminal 1 performs a random access procedure to the base station (925) and requests the resource for the communication with the terminal 2 to the base station (927). Thereafter, if a resource for communication with the terminal 2 is allocated from the base station (929), the terminal 1 transmits data to the terminal 2 with the allocated resource (931).

FIG. 10 is a diagram illustrating an operation sequence of a terminal to which the third embodiment of the D2D data transmission method proposed in the present invention is applied.

Data to be transmitted to the terminal in the sleep mode is generated (1001). For example, the data to be transmitted may occur due to a phone call, a picture, a file, or the like.

The terminal determines whether there is an ACB parameter received from the base station before or after data to be transmitted is generated (1003).

If there is no received ACB parameter, or if there is an ACB parameter but it is determined that the access is not blocked, the terminal may perform a random access procedure to the base station (1021) and transmit a data or resource request message to the base station ( 1023).

However, if it is determined that the received ACB parameter is present and the connection is blocked (1005), the UE, when the cell (re) selects the base station for the base station, for a predetermined time or until a predetermined event occurs thereafter. In operation 1007, a cell selection or cell reselection procedure is performed to select another cell. The predetermined time may be transmitted by the base station together with the ACB parameter, or may use a fixed value defined in the standard. In addition, the predetermined event may be, for example, when data to be sent to the base station occurs. In addition, the cell selection or cell reselection procedure follows the contents of the 3GPP TS 36.304 standard.

11 is a diagram illustrating an example of a message flow to which the fourth embodiment of the method for transmitting D2D data proposed in the present invention is applied.

In this example, UE 1 1101 is in an RRC dormant state or an RRC connected state, and assumes a situation in which UE 2 1103 directly sends data to UE 2 1103 using D2D communication. In addition, it is assumed that the terminal 1 is located within the coverage of the base station 1105 to allocate resource for D2D communication from the base station, that is, to use the above-described first D2D transmission scheme.

Data to be transmitted to the terminal 1 1101 is generated (1111). For example, the data to be transmitted may occur due to a phone call, a picture, a file, or the like. In more detail, the following situation may occur.

When the D2D data to be transmitted arrives in the buffer (or when the D2D data to be transmitted is generated on a Logical Channel (LCH) configured for D2D communication); or

When D2D data to be transmitted is generated by the terminal in the RRC dormant state and starts performing a random access procedure (or starts to perform an RRC connection establishment procedure or when a random access preamble is transmitted); or

When a D2D data to be transmitted by the UE in the RRC connected state is generated and a scheduling request transmission procedure is triggered to transmit the same (or when the corresponding scheduling request is transmitted); or

When the UE in the RRC connected state generates D2D data to transmit and starts performing a random access procedure (or a random access preamble is transmitted) (in this case, if the UE does not set a separate resource to send a scheduling request)

In the above situation, the terminal starts the timer T1 (tentative name) proposed in the present invention (1113). The timer T1 is broadcasted by being included in a system information block or the like by the base station, or is set to dedicated using a separate RRC layer message (for example, an RRC Connection Reconfiguration message) for each terminal, or fixed by a communication standard. You can use the value.

Meanwhile, the terminal 1 may receive the aforementioned ACB parameter from the base station 1105 before or after data to be transmitted is generated (1115).

If the ACB parameter is received, the terminal 1 determines whether the connection is blocked as described above (1117). If it is determined that access to the base station is blocked, the terminal cannot transmit a resource request message to the base station for D2D communication.

Meanwhile, the terminal 1 does not transmit a message (Buffer Status Report) indicating the buffer status of the D2D data to the base station until the timer T1 expires, or does not transmit the D2D data causing the start of the timer T1 to the base station. If not, the terminal starts the timer T2 proposed in the present invention (1119). The timer T2 is broadcasted by being included in a system information block or the like by the base station, or is set exclusively using a separate RRC layer message (for example, an RRC connection reconfiguration message) for each terminal, or is fixed by a communication standard. You can use the value.

When the timer T2 starts, although the terminal 1 is currently located in the coverage of the base station, the terminal does not make a resource request to the base station to transmit data, and selects a radio resource for D2D data transmission by itself (1121). (1123) The D2D data transmission is performed (1125). As a method of selecting a radio resource to be transmitted by itself, a method of detecting whether there is another terminal currently using radio resources (carrier sensing), or resource allocation information for D2D terminals transmitted by a D2D terminal or transmitted by a base station (D2D scheduling assignment information) and the like may be utilized. The radio resource is a resource allocated separately for the case where the terminal selects a radio resource to be used by itself. In addition, the radio resource may be broadcast in a system information block or the like, may be allocated to each terminal exclusively using an RRC layer message, or a fixed resource determined by a communication standard may be used.

Before the timer T2 expires, the terminal 1 selects a radio resource for D2D data transmission by itself (1121) (1123) and performs D2D data transmission (1125).

Thereafter, when the timer T2 ends and the terminal 1 generates data to be transmitted (1131), as described above, the terminal 1 starts the timer T1 (1133) and the terminal 1 operates in the RRC sleep state. In operation 1137, the terminal 1 determines whether to block access through reception of an ACB parameter.

If the terminal 1 successfully transmits a message (Buffer Status Report) indicating the buffer status of the D2D data to the base station until the timer T1 expires (1141), or D2D data that caused the timer T1 to start When transmitting to the base station (1145), the terminal 1 stops the timer T1, and performs the D2D data communication by receiving the resource allocation from the base station by using the above-described first D2D transmission scheme.

When the data to be transmitted is generated (1201), that is, when the following situation occurs in more detail, the terminal starts the timer T1 (1203).

Thereafter, when the terminal successfully transmits a message (Buffer Status Report) indicating the buffer status of the D2D data to the base station until the timer T1 expires or transmits the D2D data causing the start of the timer T1 to the base station. If the terminal 1205, the terminal stops the timer T1 (1207), using the above-described first D2D transmission scheme, it is determined to perform the D2D data communication by receiving the resource allocation from the base station (1219) and terminates the procedure. (1221).

On the other hand, if the terminal does not successfully transmit a message (Buffer Status Report) indicating the buffer status of the D2D data to the base station until the timer T1 expires, or transmits the D2D data causing the start of the timer T1 to the base station If not, the terminal starts the timer T2 proposed in the present invention (1211).

When the timer T2 starts, although the UE is currently located in the coverage of the base station, the terminal does not make a resource request to the base station to transmit data and selects a radio resource for D2D data transmission by itself. Perform the transfer (1215). As a method of selecting a radio resource to be transmitted by itself, a method of detecting whether there is another terminal currently using radio resources (carrier sensing), or resource allocation information for D2D terminals transmitted by a D2D terminal or transmitted by a base station (D2D scheduling assignment information) and the like may be utilized. The radio resource is a resource allocated separately for the terminal to select a radio resource to be used by itself as described above, which is broadcasted as a system information block or the like, or dedicated to each terminal using an RRC layer message, or a communication standard The fixed resources set in step can be used.

Thereafter, the terminal selects a radio resource for D2D data transmission by itself until the timer T2 expires (1213) and performs D2D data transmission (1215).

Thereafter, when the timer T2 is terminated, the terminal terminates the procedure (1221). If the D2D data to be transmitted by the UE is generated, the present process is restarted (1201), and the method determines whether to transmit the D2D data.

Through the above method, the terminal may perform terminal-to-terminal data communication even when the access to the base station is blocked.

13 is a block diagram showing the configuration of a terminal according to an embodiment of the present invention.

Referring to FIG. 13, a terminal according to an exemplary embodiment of the present invention includes a transceiver 1305, a controller 1310, a multiplexing and demultiplexing unit 1320, a control message processor 1335, and various upper layer processors 1325. 1330.

The transceiver 1305 receives data and a predetermined control signal through a forward channel of a serving cell and transmits data and a predetermined control signal through a reverse channel. When a plurality of serving cells are set, the transceiver 1305 performs data transmission and reception and control signal transmission and reception through the plurality of serving cells.

The multiplexing and demultiplexing unit 1320 multiplexes data generated by the upper

layer processing unit

1325 or 1330 or the control message processing unit 1335, or demultiplexes the data received by the transmitting and receiving unit 1310 so as to provide an appropriate upper layer processing unit 1325. 1330 or the control message processor 1335.

The control message processing unit 1335 processes the control message received from the base station and takes necessary actions.

The upper

layer processing unit

1325 and 1330 may be configured for each service, and the multiplexing and demultiplexing unit 1315 may process data generated from a user service such as FTP (File Transfer Protocol) or Voice over Internet Protocol (VoIP). Or the data transmitted from the multiplexing and demultiplexing unit 1315 is processed and delivered to the service application of the upper layer.

The control unit 1310 multiplexes and decodes the scheduling command, for example, uplink resource allocation information received through the transceiver unit 1305 and the transceiver unit 1305 so that uplink transmission is performed on an appropriate transmission resource at an appropriate time. The multiplexer 1315 is controlled.

In the present invention, when the terminal in the dormant mode receives data to be transmitted from the upper layer device 1325 (1330), it determines whether the connection is blocked from the control message processing unit 1335 to determine the type of data received from the higher layer device. Accordingly, using the method described in the above-described first embodiment, second embodiment, or third embodiment, a procedure of changing a connection method, performing a connection determination, or selecting or reselecting another cell is performed.

14 is a block diagram illustrating a configuration of a base station according to an embodiment of the present invention. The base station apparatus of FIG. 14 includes a transceiver 1405, a controller 1410, a multiplexing and demultiplexing unit 1420, and a control message processing unit 1435. ), And various upper

layer processing units

1425, 1430, and a scheduler 1415.

The transceiver 1405 transmits data and a predetermined control signal through a downlink carrier and receives data and a predetermined control signal through an uplink carrier. When a plurality of carriers are set, the transceiver 1405 transmits and receives data and control signals through the plurality of carriers.

The multiplexing and demultiplexing unit 1420 multiplexes data generated by the upper

layer processing unit

1425 or 1430 or the control message processing unit 1435, or demultiplexes the data received by the transmitting and receiving unit 1405 so as to provide an appropriate upper layer processing unit 1425. 1430, the control message processor 1435, or the controller 1410. The control message processor 1435 processes the control message transmitted by the terminal to take a necessary action, or generates a control message to be transmitted to the terminal and delivers the control message to the lower layer.

The

upper layer processor

1425 and 1430 may be configured for each terminal service, and may process data generated from a user service such as FTP or VoIP, and transmit the data to the multiplexing and demultiplexing unit 1420 or the multiplexing and demultiplexing unit 1420. 1420 processes the data transmitted from 1420 and delivers the data to the service application of the upper layer.

The controller 1410 determines when the terminal transmits channel state information and the like to control the transceiver.

The scheduler 1415 allocates a transmission resource to the terminal at an appropriate time in consideration of the buffer state, the channel state, and the active time of the terminal, and processes the signal transmitted by the terminal to the transceiver or transmits the signal to the terminal. do.

In the present invention, according to the above-described embodiment, the base station generates, in the control message processor 1435, an ACB parameter for D2D communication proposed by the present invention, or an indicator allowing access without performing an ACB check for D2D communication. And, by broadcasting it to the terminals in the cell, and informs, so that the terminal can change the connection mode, determine the connection disconnection, or select or reselect the cell.

Using the proposed method, using the proposed method, the terminal may perform terminal-to-terminal data communication even in a situation in which access to the base station is blocked.

In the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims to be described below but also by the equivalents of the claims.

Claims

In a device-to-device (D2D) communication method of a terminal in a wireless communication system,

Attempting to connect to a base station to request a resource for performing the D2D communication;

Selecting a resource for performing the D2D communication based on resource allocation information for a preset D2D terminal when the access attempt fails;

And performing D2D communication using the selected resource.
The method of claim 1,

The resource allocation information,

D2D communication method characterized in that it is included in the system information block 18 (SIB 18) received from the base station.
The method of claim 1,

Performing the D2D communication,

Transmitting scheduling allocation information and data.
The method of claim 1,

The resource selection step,

D2D communication method, characterized in that for selecting a resource based on the resource set indicated by the resource allocation information.
The method of claim 1,

The connection attempt step,

In a dormant mode, detecting generation of data; And

And determining whether the generated data is data for the D2D communication.
The method of claim 1,

If the connection attempt fails,

D2D communication method comprising the case that the connection is delayed.
The method of claim 1,

If the connection attempt fails,

D2D communication method comprising the case that the access is blocked from the base station.
A terminal performing a device to device (D2D) of a terminal in a wireless communication system,

Communication unit for transmitting and receiving a signal with another network entity;

Attempts to access a base station to request a resource for performing the D2D communication, selects a resource for performing the D2D communication based on resource allocation information for a preset D2D terminal when the access attempt fails, and selects the selected resource And performing D2D communication using resources.
The method of claim 8,

The resource allocation information,

Terminal included in the system information block 18 (SIB 18) received from the base station.
The method of claim 8,

The control unit,

And controlling to transmit the scheduling allocation information and the data.
The method of claim 8,

The control unit,

And selecting a resource based on the resource set indicated by the resource allocation information.
The method of claim 8,

The control unit,

In the dormant mode, the terminal characterized in that it detects the generation of data, and to determine whether the generated data is the data for the D2D communication.
The method of claim 8,

If the connection attempt fails,

Terminal comprising a case where the connection is delayed.
The method of claim 8,

If the connection attempt fails,

Terminal, characterized in that it comprises a case that the access is blocked from the base station.