KR20160018313A - Method and apparatus for transmission/reception of d2d signal - Google Patents

Abstract

The present invention relates to a method for transmission/reception of a D2D signal in a wireless communications system, including the steps of: determining whether the transmission or reception of multiple D2D signals is set to be performed simultaneously in a single spectrum so a crash of the multiple D2D signals occurs; deciding the D2D signal to be transmitted or received in the spectrum wherein the crash occurred, based on the priorities of the D2D signals; and transmitting or receiving the D2D signal which was decided in the prior step. According to the present invention, in a situation where the D2D signals crash, a terminal is capable of performing the transmission and reception of D2D signals in accordance with the priorities of the signals, thereby ensuring the efficiency of the D2D communications in general.

Description

TECHNICAL FIELD [0001] The present invention relates to a D2D signal transmission method,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a method and apparatus for transmitting and receiving a Device to Device (D2D) signal.

In the long term evolution (LTE) of the 3rd generation partnership project (3GPP), ProSe (Proximity Service) is allowed to be supported to meet the need for public safety. On the other hand, the discovery technique and the broadcast communication are added to the proximity-based service, so that a technology for providing compatibility in the LTE system is required. A typical proximity-based application technology is D2D (device to device) communication, and D2D communication is a communication method that has been available since the time of analog radio, and has a very long history.

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

D2D communication can be performed using a communication method using a license-exempt band such as a wireless LAN or Bluetooth, but the communication method using the license-exempt band has a disadvantage that it is difficult to provide a planned and controlled service. In particular, performance can be drastically reduced by interference. On the other hand, the direct communication between the terminals operated or provided in the licensed band or inter-system interference controlled environment can support QoS (Quality of Service), increase frequency utilization efficiency through frequency reuse, The possible distance can be increased.

In this D2d communication in the licensed band, that is, in the D2D communication based on the cellular communication, resources for D2D communication can be allocated through the base station, and the cellular uplink channel or uplink subframes can be used as the allocated resource. D2D communication includes D2D data communication and D2D control signal communication. D2D communication can be performed without control of the network unlike cellular communication, so that a plurality of D2D signals may be generated in time overlapping one terminal, that is, a collision may occur. Therefore, a solution is needed to solve such a problem.

Also, since a terminal having a single transceiver chain can not simultaneously transmit / receive signals in a plurality of frequency bands, for efficient D2D communication in a license band, when a collision occurs between D2D signals, There is a need to determine whether or not to perform processing with priority.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for transmitting and receiving D2D signals in a wireless communication system.

It is another object of the present invention to provide a method and apparatus for defining and determining a priority of a D2D signal in a wireless communication system.

Another aspect of the present invention is to provide a method and apparatus for transmitting and receiving priority-based D2D signals in a wireless communication system.

It is another object of the present invention to provide a method and apparatus for preventing collision of a D2D signal in a wireless communication system.

According to an aspect of the present invention, there is provided a terminal for performing D2D communication in a wireless communication system. The terminal includes a transmitter configured to transmit a D2D signal, a receiver configured to receive a D2D signal, and a controller configured to control the transmitter and the receiver, wherein the controller is configured to simultaneously transmit or receive a plurality of D2D signals in the same spectrum And a multiplexing unit for determining or scheduling a D2D signal to be transmitted or received in the spectrum in which the collision occurs based on the priority between the D2D signals, do.

According to another aspect of the present invention, there is provided a method of transmitting and receiving a D2D signal performed by a terminal in a wireless communication system. The method comprising the steps of: determining whether a collision occurs, the transmission or receipt of a plurality of D2D signals being set to be performed simultaneously in the same spectrum; determining whether a collision occurs or not in a spectrum in which the collision occurs based on a priority among the plurality of D2D signals; Determining a D2D signal to be received, and transmitting or receiving the determined D2D signal.

According to the present invention, in a situation where D2D signals collide with each other, the mobile station can perform transmission / reception of D2D signals according to priorities, and can ensure overall D2D discovery and D2D communication efficiency.

1 shows a wireless communication system to which the present invention is applied.
2 and 3 schematically show the structure of a radio frame applied to the present invention.
4 is a diagram for explaining the concept of a cellular network-based D2D communication applied to the present invention.
5 is a diagram illustrating an example of a D2D discovery resource to which the present invention is applied.
6 is a diagram illustrating examples of a D2D discovery resource set to which the present invention is applied.
7 is a diagram illustrating examples of a D2D discovery resource setting structure in a D2D discovery resource set to which the present invention is applied.
8 to 12 are diagrams illustrating the information transfer between terminals and a base station for D2D communication according to the present invention.
Figure 13 shows an example of a potential collision between D2D signals.
Figure 14 shows another example of a potential conflict between D2D signals.
15 is an example of a flowchart showing operations of a terminal according to the present invention.
16 is an example showing a block diagram of a terminal according to the present invention.

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

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

Referring to FIG. 1, a wireless communication system 10 is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system 10 includes at least one base station 11 (evolved-NodeB, eNB). Each base station 11 provides communication services to specific cells (15a, 15b, 15c). The cell may again be divided into multiple regions (referred to as sectors).

A user equipment (UE) 12 may be fixed or mobile and may be a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, (personal digital assistant), a wireless modem, a handheld device, and the like. The base station 11 may be referred to by other terms such as a base station (BS), a base transceiver system (BTS), an access point, a femto base station, a home node B, and a relay. Cells are meant to cover various coverage areas such as megacell, macrocell, microcell, picocell, and femtocell.

Hereinafter, downlink (DL) refers to communication from the base station 11 to the terminal 12, and uplink (UL) refers to communication from the terminal 12 to the base station 11. In the downlink, the transmitter may be part of the base station 11, and the receiver may be part of the terminal 12. In the uplink, the transmitter may be part of the terminal 12, and the receiver may be part of the base station 11. There are no restrictions on multiple access schemes applied to wireless communication systems. (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA , OFDM-CDMA, and the like. A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

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

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

2 and 3 schematically show the structure of a radio frame applied to the present invention. In particular, FIG. 2 is a diagram for explaining the concept of a cellular network-based D2D communication applied to the present invention, and FIG. 3 shows an example of a structure of a D2D discovery resource setting.

Referring to FIG. 2 and FIG. 3, one radio frame includes ten subframes, and one subframe includes two consecutive slots. A basic time (length) unit for transmission control in a radio frame is referred to as a transmission time interval (TTI). The TTI may be 1ms. The length of one subframe (1 subframe) is 1 ms, and the length of one slot may be 0.5 ms.

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

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

A resource element (RE) represents a smallest time-frequency unit to which a modulation symbol of a data channel or a modulation symbol of a control channel is mapped. A resource block (RB) is a resource allocation unit and includes time-frequency resources corresponding to 180 kHz on the frequency axis and 1 slot on the time axis. The resource block may be referred to as a PRB (Physical Resource Block). On the other hand, a resource block pair means a resource block unit including two consecutive slots on the time axis.

Several physical channels can be used in the physical layer, and the physical channels can be mapped to the radio frame and transmitted. As a downlink physical channel, a physical downlink control channel (PDCCH) / enhanced physical downlink control channel (EPDCCH) includes a resource allocation of a paging channel (PCH) and a downlink shared channel (DL-SCH) Request information. The PDCCH / EPDCCH may carry an uplink grant informing the UE of the resource allocation of the uplink transmission. PDCCH and EPDCCH are different in the resource area to be mapped. A DL-SCH is mapped to a PDSCH (Physical Downlink Shared Channel). The Physical Control Format Indicator Channel (PCFICH) informs the UE of the number of OFDM symbols used in the PDCCH and is transmitted every subframe. The Physical Hybrid ARQ Indicator Channel (PHICH) is a downlink channel that carries an HARQ (Hybrid Automatic Repeat reQuest) ACK (Acknowledgment) / NACK (Non-acknowledgment) signal, which is a response of an uplink transmission. The HARQ ACK / NACK signal may be referred to as an HARQ-ACK signal.

As an uplink physical channel, Physical Random Access Channel (PRACH) carries a random access preamble. The Physical Uplink Control Channel (PUCCH) includes HARQ-ACK, which is a response of downlink transmission, channel status information (CSI) indicating a downlink channel status, for example, a channel quality indicator (CQI) Uplink control information such as a precoding type indicator (PTI), a rank indicator (RI), and the like. The Physical Uplink Shared Channel (PUSCH) carries an Uplink Shared Channel (UL-SCH).

PUSCH, and the uplink data may be a transport block (TB), which is a data block for a UL-SCH transmitted during a TTI (Transmission Time Interval). The transport block may include user data. Alternatively, the uplink data may be multiplexed data. The multiplexed data may be a multiplexed transport block for UL-SCH and UL control information. That is, if there is user data to be transmitted in the uplink, the uplink control information may be multiplexed together with the user data and transmitted through the PUSCH.

Meanwhile, in recent years, in the frequency band of the wireless communication system or in other bands, D2D communication using direct transmission / reception technology of the wireless communication system but directly exchanging user data between terminals without going through an infrastructure (for example, a base station) A plan is being considered. D2D communication enables wireless communication in an area other than a limited wireless communication infrastructure and reduces the network load of the wireless communication system. In addition, D2D communication provides advantages such as disaster information and the like can be transmitted to terminals even when the base stations do not operate smoothly in a situation of war, disaster or the like.

A terminal transmitting a signal based on D2D communication is referred to as a transmission terminal (Tx UE), and a terminal receiving a signal based on D2D communication is defined as a reception terminal (Rx UE). The transmitting terminal transmits a discovery signal, a D2D control signal, or a D2D data signal, and the receiving terminal can receive the discovery signal, the D2D control signal, or the D2D data signal. The roles of the transmitting terminal and the receiving terminal may be changed. On the other hand, the signal transmitted by the transmitting terminal may be received by two or more receiving terminals. Also, a signal transmitted by two or more transmitting terminals may be selectively received from one receiving terminal. The D2D signal can be transmitted through the uplink resources. Therefore, the D2D signal can be mapped on the uplink subframe and transmitted from the transmitting terminal to the receiving terminal, and the receiving terminal can receive the D2D signal on the uplink subframe.

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

Referring to FIG. 4, a cellular communication network including a first base station 410, a second base station 420, and a first cluster 430 is configured. The first terminal 411 and the second terminal 412 belonging to the cell provided by the first base station 410 perform communication through a normal access link (cellular link) through the first base station 410. [ This is an In-coverage-single-cell D2D communication scenario. Meanwhile, the first terminal 411 belonging to the first base station 410 can perform the D2D communication with the fourth terminal 421 belonging to the second base station 420. This is an In-coverage-multi-cell D2D communication scenario. The fifth terminal 431 other than the network coverage may also create one cluster 430 together with the sixth terminal 432 and the seventh terminal 433 to perform D2D communication with them. This is an Out-of-coverage D2D communication scenario. Here, the fifth terminal 250 may operate as a cluster head (CH) of the first cluster. A cluster head is a terminal (or unit) that can be a reference for at least synchronization purposes, and is sometimes called a terminal that is responsible for allocating resources according to different purposes. The cluster header may include an ISS (Independent Synchronization Source) for synchronization of Out-of-coverage terminals.

Also, the third terminal 413 can perform terminal-to-terminal communication with the sixth terminal 432, which is a partial-coverage D2D communication scenario.

D2D communication includes direct communication for transmitting and receiving data and control information between D2D terminals for the purpose of public safety and includes a D2D discovery procedure and a D2D synchronization A procedure can be performed. The D2D discovery signal may be used solely for commercial purposes, for example, for advertising purposes.

In order to perform D2D data transmission / reception through D2D communication, D2D control information must be transmitted / received between the terminals. The D2D control information may be referred to as a Scheduling Assignment (SA) or a D2D SA. The D2D Rx terminal can perform D2D data reception based on the SA. The SA includes, for example, a New Data indicator (NDI), a Target ID, a Redundancy Version indicator, an MCS indication, a Resource Pattern for Transmission (RPT) An instruction, a power control instruction, or the like.

Here, NDI indicates whether the current transmission is a repetition of data, i.e., retransmission or new. The receiver can combine the same data based on NDI. The target ID indicates an ID for terminals intended to be delivered with the corresponding data MAC PDU. The data MAC PDU can be transmitted in a unicast manner according to the group cast, the broadcast, or even the setting according to the ID value. The RV indicator indicates the redundancy version by specifying the different starting points in the circular buffer for the encoded buffer reading. Based on the RV indicator, the transmitting terminal may choose various redundancy versions for repeated transmission of the same packet. The MCS indication indicates the MCS level for D2D communication. However, the MCS for D2D communication (e.g., SA or Data) may be fixed to QPSK. The transmission resource pattern indication indicates to which time / frequency physical resource the corresponding D2D data is allocated to be transmitted. The power control instruction will be a command for the terminal that has received the information to control the size of power appropriate for the D2D transmission.

At the perspective of the Tx terminal, the Tx terminal can operate in two modes of resource allocation for D2D communication.

Mode 1 is the case where a base station or relay node (hereinafter referred to as a base station, which may include a relay node) schedules certain resource (s) for D2D communication. That is, in the mode 1, the specific resource (s) used for transmitting the D2D data and the D2D control information of the Tx terminal is designated by the base station or the relay node. Mode 2 is a case where the UE directly selects a specific resource (s) in the resource pool. That is, in mode 2, the Tx terminal directly selects specific resource (s) for transmission of D2D data and D2D control information.

A D2D capable terminal supports at least mode 1 or 2 for in-coverage D2D communication. A D2D capable terminal supports mode 2 for at least out-of-coverage or edge-of-coverage D2D communication.

In Mode 1, the location of the resource (s) for transmission of the D2D control information and the location of the resource (s) for transmission of the D2D data is given by the base station. That is, for the D2D SA and the data transmission, the same grant is given to the UE by transmitting the (E) PDCCH from the base station to the DCI message format having the same size as DCI format 0.

In Mode 2, a resource pool for transmission of D2D control information (e.g., SA) may be pre-configured and / or semi-statically allocated. In this case, the Tx terminal can select a resource for D2D control information in the resource pool for transmission of D2D control information.

D2D discovery is performed on the D2D discovery resource. For example, the D2D terminal may communicate with each other through discovery resources (hereinafter referred to as D2D discovery resources) randomly selected (other than network coverage) or set by the base station (within network coverage) within each discovery period A discovery signal can be transmitted. In the case of random resource selection, the transmission of the discovery signal is based on a fixed or adaptive transmission probability from a pre-configured or configured nominal transmission probability. May determine the resources for the user.

5 shows an example of a D2D discovery resource according to the present invention.

Referring to FIG. 5, one D2D discovery resource may consist of n contiguous PRBs in frequency and one subframe. In this case, inter-slot frequency hopping in the subframe is not performed. The n may be, for example, 2 or 3.

A set of D2D resources may be used for repeated transmission of a Medium Access Control Protocol Data Unit (MAC PDU) (hereinafter referred to as a Discovery MAC PDU) carrying a discovery signal within a discovery interval.

Figure 6 shows examples of D2D discovery resource sets according to the present invention.

Referring to FIG. 6, the D2D discovery resource set in the discovery interval may include adjacent D2D discovery resources in the time domain, or may include non-contiguous D2D discovery resources. That is, the repeated D2D discovery resources in the D2D discovery resource set may be contiguous or discontinuous in the time domain.

FIG. 7 shows examples of the D2D discovery resource setting structure in the D2D discovery resource set according to the present invention.

Referring to FIG. 7, each pattern represents the resources in each D2D discovery resource set. There can be a plurality of D2D discovery resource sets within one discovery interval, and D2D discovery resources in one D2D discovery resource set can be adjacent or non-adjacent to each other on the time axis, and frequency hopping (interframe frequency hopping) As shown in FIG. From the perspective of the receiving terminal, the discovery signal can be monitored within the resource pool for D2D reception. The resource pool for the corresponding D2D reception may take the form of a superset rather than the resource pool for the D2D transmission.

On the other hand, the definition of the discovery interval can be classified according to the discovery type 1 and the type 2B. For Type 1, the discovery interval represents the periodicity of the resources allocated for transmission of the D2D discovery signal in the cell. For Type 2B, the discovery interval represents the interval of the resources for receiving the D2D discovery signal from the cell. Multiple discovery intervals of varying lengths may be used. In Type 2B, the network can set specific resources for the transmission of the D2D discovery signal.

Meanwhile, a D2D Discovery transmission probability may be set to determine whether to transmit the D2D discovery signal.

The D2D terminal performing D2D discovery signal transmission randomly selects resources in the discovery interval and transmits the discovery MAC PDU. In this case, the terminal does not always transmit the found MAC PDU in all the detection intervals, and can decide which resource to transmit the found MAC PDU. Whether or not to transmit the found MAC PDU on the resource can be determined based on the D2D discovery transmission probability. The terminal selects randomly discovered resources (in case of type 1) or network setting (in case of type 2) in the discovery resource set in the set discovery interval, and transmits the discovery MAC PDUs (repeatedly) on the selected discovery resources .

For example, the D2D discovery transmission probability may be determined based on a period / offset. That is, if it is known which detection period and the time / frequency offset are known, the D2D detection signal can be transmitted at that point.

In another example, the D2D discovery transmission probability may be based on a fixed probability or an adaptive probability. (1) Based on the fixed probability, it can be determined whether to transmit the D2D discovery signal in the discovery resource based on the random function including the probability value P. (2) Based on the adaptation probability, it is similar to the one based on the fixed probability, but the probability value P adaptively changes. For example, if there is no D2D discovery signal transmission in the last interval, the probability value P increases by k, and if the D2D discovery signal transmission occurs, the probability value P may increase by m. Or the probability value P gradually increases, and may decrease to some extent if the specific condition is satisfied.

 In the present invention, it is assumed that a D2D synchronization signal (D2D Synchronization Signal, D2DSS) and a physical D2D synchronization channel (PD2DSCH) are set by a network or located in a predetermined resource to effectively support D2D discovery or D2D communication do. Therefore, when the D2DSS or PD2DSCH is located on the resource for D2D discovery or D2D communication (SA / data), the resource can follow the multiplexing of the D2D signal and the WAN (Wide Area Network) signal. Or the D2D sync signal and the D2D sync channel can independently apply multiplexing with other signals. Wide Area Network (WAN) refers to a network that provides voice / data traffic to mobile terminals by configuring a wide coverage in a conventional cellular network. WCDMA, LTE, WiMax, etc. This may be the case. Thus, radio access networks are commonly referred to as WANs.

8 to 12 illustrate information transfer between terminals and a base station for D2D communication according to the present invention. For example, FIG. 8 to FIG. 12 show a flow chart of resource setting and transmission / reception of signals between a base station for D2D discovery signal and data communication, D2D Tx and D2D Rx.

FIG. 8 is a diagram illustrating a process of transmitting and receiving Type 1 D2D discovery in an IDLE mode terminal in a wireless communication system to which the present invention is applied.

Referring to FIG. 8, TxUE and RxUE may obtain information on a Tx / Rx resource pool from the base station via SIB (810, 812). The TxUE and RxUE are in the idle mode, and the base station broadcasts the SIB information and provides information on the resource pool for the D2D communication.

The TxUE determines a discovery transmission (820), and selects a discovery resource in a specific time / frequency domain for the discovery transmission based on the obtained information on the resource pool (830). The discovery resource may be selected through a random function, which may be distinguished by the identification information of the terminal.

The TxUE transmits a discovery signal through the selected discovery resource (840). The RxUE receives the discovery signal (850). This can be called discovery type 1.

9 is a diagram illustrating a process of transmitting and receiving Type 1 D2D discovery in an RRC connected mode terminal in a wireless communication system according to the present invention.

If the terminal is RRC connected, type 1 discovery is established through dedicated RRC signaling, and the base station can indicate the corresponding resource pool information.

Referring to FIG. 9, each of the RRC connection modes TxUE / RxUE requests a type 1 discovery transmission acknowledgment to the base station (900, 902). After confirming the discovery approval request received from each terminal, the base station approves the approval based on the context of the terminal (905, 907).

At this time, the base station can transmit configuration information for type 1, information on the Tx / Rx resource pool, and the like through dedicated signaling to the RRC connection modes TxUE and RxUE, respectively (910 and 912). The Tx UE and the Rx UE are in the RRC connection mode, and the BS can transmit an RRC signal including configuration information for the D2D discovery to each MS in the RRC configuration information.

In step 920, the Tx UE determines 920 a discovery transmission, and then selects a discovery resource in a specific time / frequency domain for the discovery transmission based on the obtained resource pool information. The discovery resource may be selected through a random function, which may be distinguished by the identification information of the terminal. The TxUE transmits a discovery signal through the selected discovery resource (940). The RxUE receives the discovery signal (950). Here, FIG. 9 illustrates a process in which Discovery Type 1 is performed.

10 is a diagram illustrating another example of transmitting / receiving type 2B D2D discovery in the RRC connection mode in the wireless communication system according to the present invention.

Referring to FIG. 10, the D2D discovery type 2B is performed in the RRC connection mode. D2D discovery type 2B can only be performed in the RRC connection mode.

In one example, the base station may transmit information for type 2 and information for a Tx / Rx resource pool for type 2 (1010, 1012) via dedicated signaling to each of the RRC connection modes TxUE and RxUE, . Of course, the base station may allow the terminal to perform type 2B discovery before the terminal 2B or perform the type 2B discovery according to the terminal request.

Then, the Tx UE determines 1020 the discovery transmission, and then selects / confirms 1020 the discovery resource in the specific time / frequency domain set through the dedicated signal.

Therefore, the TxUE transmits the discovery signal only through the set discovery resource (1040). The RxUE receives the discovery signal (1050). Here, FIG. 10 shows a process in which Discovery Type 2 is performed.

11 is a diagram illustrating another process for performing D2D data communication in the RRC connection mode in the wireless communication system according to the present invention.

Referring to FIG. 11, a mode 2 ProSe direct communication is performed prior to the mode 2 communication in the RRC connection mode. For example, the mode 2 operation is used only in exceptional cases such as RLF, and the mode 1 operation can be performed by default. The terminal in the idle mode performs the mode 2 operation based on the information indicated by the SIB.

More specifically, each of the RRC connection modes TxUE / RxUE requests a ProSe direct communication transmission acknowledgment to the base station (1100, 1102). The base station confirms the ProSe direct communication transmission approval request received from each terminal, and then permits the approval based on the context of the terminal (1105, 1107).

The base station may transmit configuration information for mode 2 and information for a Tx / Rx resource pool for mode 2 (1110, 1112) through a dedicated signaling to each of the RRC connection modes TxUE and RxUE. The Tx UE and the Rx UE are in the RRC connection mode, and the BS can transmit an RRC signal including information for the mode 2 D2D data communication to the RRC configuration information.

The Tx UE determines 1120 a communication transmission, and then selects / determines a resource for communication (SA / data) through information on the acquired / set resource pool 1130.

The TxUE transmits the communication SA / data through the selected resource (1140). The RxUE receives the communication data (1150).

12 is a diagram illustrating another process of transmitting and receiving D2D discovery in the RRC connection mode in the wireless communication system according to the present invention.

Referring to FIG. 12, a mode 1 ProSe direct communication is performed before the mode 1 communication is performed in the RRC connection mode.

More specifically, each of the RRC connection modes TxUE / RxUE requests ProSe direct communication transmission acknowledgment to the base station (1200, 1202). The base station confirms the ProSe direct communication transmission approval request received from each terminal, and then permits the approval based on the context of the terminal (1205, 1207).

The base station may transmit configuration information for mode 1 and information about a Tx / Rx resource pool for mode 1 (1210, 1212) through a dedicated signaling to each of the RRC connection modes TxUE and RxUE. The Tx UE and the Rx UE are in the RRC connection mode, and the BS can transmit an RRC signal including information for the mode 1 D2D data communication to the RRC configuration information.

The Txue determines 1220 the transmission of the communication, and then reports the buffer status of the generated D2D data through the ProSe BSR (1224). The base station receiving the ProSe BSR from the TxUE allocates a ProSe SA / ProSe data grant for D2D data transmission. The ProSe SA / ProSe data grant may be indicated 1228 via PDCCH or EPDCCH.

The TxUE acquiring the ProSe SA / ProSe data grant selects / determines resources for the established resource pool and resources for communication (SA / data) based on the SA / data grant (1230).

The TxUE transmits ProSe SA / ProSe data (communication data) through the selected resource (1240). The RxUE receives communication SA / data (1250).

When a plurality of D2D signals are temporally superimposed on one terminal, collision between D2D signals may occur. However, since existing terminals, especially terminals with a single transceiver chain, can not transmit / receive in multiple frequency bands at the same time, for effective D2D communication in the licensed band, It is necessary to determine whether or not to carry out the processing with ranking.

Accordingly, the present invention is directed to multiplexing D2D signals when a plurality of D2D signals are generated simultaneously. In particular, a method for multiplexing D2D signals between terminals having only a single transmission / reception chain will be described. The methods described herein are also applicable to multi-carrier scenarios. For example, the present invention can be applied to multiplexing of terminals having a single transmit / receive chain on the uplink spectrum (on FDD) for the cellular spectrum (carrier # 0) and D2D.

A D2D signal that may be considered in the present invention includes a D2D discovery signal and a D2D communication signal. The D2D discovery signal can be divided into Type 1 and Type 2. The Type 1 D2D discovery signal is transmitted on a randomly selected resource within the D2D discovery resource set, and the Type 2 D2D discovery signal is transmitted on the established resource based on the network configuration. The D2D communication signal includes SA and D2D data. The SA transmission for D2D communication is indicated by the DCI format having the same size as DCI format 0 in mode 1 and in the case of mode 2, using the resources selected randomly in the SA resource pool.

Where the SA resource pool can be preconfigured in out-of-coverage D2D communication scenarios and in the case of in-coverage / partial-coverage D2D communication scenarios, the SIB / dedicated signaling ). ≪ / RTI > Or fixed to a specific location. For example, a specific location within a resource pool for D2D data transfer.

D2D data is indicated by SA for both mode 1 and mode 2. Meanwhile, a resource pattern for transmission (RPT) may be used for D2D data transmission. In this case, the pattern for the time domain resource may be referred to as T-RPT, and the pattern for the frequency domain resource may be referred to as F-RPT. However, the indication for a frequency domain resource may be specified or dictated by a particular hopping pattern.

FIG. 13 shows an example of a potential collision between D2D signals to which the present invention is applied. 13 assumes a single carrier scenario. Fig. 14 shows another example of a potential collision between D2D signals to which the present invention is applied. Figure 14 assumes a multicarrier scenario.

13 and 14, a collision may occur between the D2D discovery signal and the D2D data (or SA) on one carrier, and a collision may occur between the D2D data (or SA) of one carrier and SA (or D2D Data) may occur. This is because D2D discovery and D2D communication may not be controlled by one network at each transmission timing. For example, the terminal may monitor the reception of a discovery signal transmitted on other PLMNs (or carriers) for a specific time period to receive an inter-PLMN discovery signal. At the same time, D2D signal transmission or reception may occur on the serving PLMNs (or carriers).

In this case, when a plurality of D2D signals according to the present invention are generated simultaneously, a method of multiplexing D2D signals is as follows.

The D2D sync signal and the D2D sync channels have higher priority than any other D2D channels and can perform D2D transmission based on this prior to applying the methods of the following embodiments. That is, the above-mentioned D2D synchronization signal and synchronization channel means that it can be transmitted first in case of a time overlap with another D2D discovery channel, a D2D control channel (SA), a D2D data channel, or in the event of a collision, Otherwise, the D2D channels may not be transmitted or some information may be punctured. More specifically, if the D2D synchronization signal collides with the D2D control channel (SA) / data channel, puncturing is performed on the OFDM symbols overlapping with the D2D synchronization signal in the subframe where the D2D control channel is transmitted, and the D2D control The channel / data channel can be transmitted with the D2D sync signal. On the other hand, if the D2D sync channel is transmitted, if it collides with the remaining D2D channels, all of the remaining D2D channels are not transmitted. If it is not transmitted here, it does not mean all transmission including retransmission of the D2D channel, and does not transmit only the transmission of the D2D channel at the time of collision.

The method for priority among the remaining D2D channels except for the D2D sync signal and the sync channel follows the proposed embodiments below.

According to an exemplary embodiment, when a collision occurs between D2D signals, a maximum transmission power level (eg, Pmax) information and a priority based on the channel mentioned in the first embodiment are set in the setting of the resource pool set for the D2D detection channel The final priority can be determined by combining. The information on the maximum transmission power in the setting for the D2D discovery channel resource pool can have three power levels of maximum / medium / minimum. Also, the D2D data transmission power can indicate whether to follow maximum power or general open loop power control according to TPC command. Therefore, D2D data transmission with maximum power can be considered. Therefore, the power level of each channel is considered first, and the channel having the highest power is given priority. If the maximum transmission power information of the collided channels is equal, the final priority is determined in the order of data> SA> The D2D channel having the highest priority is transmitted first, and the other channels can be dropped or punctured.

For example, if the transmission of the D2D discovery signal (maximum power), the D2D SA signal (maximum power) and the transmission of D2D data (intermediate power, off-loop power control) occur within a single terminal that performs D2D on one carrier, According to the above method, the D2D data signal having the intermediate power level is dropped and the D2D discovery signal having the maximum power and the D2D SA signal can be finally transmitted through the priority of the corresponding channel.

According to the first embodiment, if a collision occurs between the D2D signals, the D2D transmission can be performed based on the priority of the detection signal> SA> data. In this case, since the discovery signal may have a long transmission period (eg, few seconds) as a main consideration, receiving a D2D discovery signal as much as possible in one discovery interval can prevent a delay in receiving the D2D discovery signal .

For example, when the transmission / reception of the detection signal occurs simultaneously with the transmission / reception of the SA, the transmission / reception of the detection signal always has priority over the transmission / reception of the SA. Therefore, this method can be considered as a method of prioritizing the transmission / reception of the detection signal.

According to the first embodiment, when the detected Tx signal and the SA Tx signal occur simultaneously in the same subframe, the SA Tx signal is dropped. This is because it is important not to miss the discovery signal in the discovery interval as much as possible, since the discovery signal transmission period is longer than the general D2D communication (SA, data) signals. Therefore, according to the first embodiment, it is possible to minimize the transmission / reception delay of the detection signal.

In addition, if the same D2D signals collide with each other in a different carrier (or PLMN, cell), the D2D signal corresponding to the serving cell (or PLMN) is transmitted or received with priority.

The second embodiment considers whether the D2D signal is a Tx signal or an Rx signal in determining the priority. In this case, whether the Tx / Rx may be treated as a more important factor in setting the priority, or the type of the D2D signal may be treated as a more important factor. For example, priorities can be set in order of discovery Tx> SA Tx> data Tx> discovery Rx> SA Rx> data Rx. As another example, priorities can be determined in the order of discovery Tx> discovery Rx> SA Tx> SA Rx> data Tx> data Rx.

According to the second embodiment, transmission (or reception) of a specific D2D signal can be prioritized over transmission (or reception) of another signal. The second embodiment may be based on the priority in the first embodiment described above. Here, the meaning of 'based on the priority in the first embodiment' means that the characteristics of the D2D signal considered in the first embodiment (If they have the same priority), it means that priority can be determined in consideration of whether Tx / Rx considered in the second embodiment. On the contrary, the priorities of the second embodiment are considered first, and if they are the same (if they have the same priority), the priorities can be determined in consideration of the consideration in the first embodiment. Alternatively, the priority may be determined regardless of the priority in the above-described first embodiment.

In the third embodiment, the priority of the D2D signals is determined based on at least one of the D2D communication mode and the discovery type.

More specifically, the priorities of the D2D signals can be determined in consideration of the D2D communication mode 1/2 and the D2D discovery type 1 / 2B. For example, priority can be determined in the order of type 2B discovery> mode 1 SA> mode 1 data> discovery of type 1> mode 2 SA> mode 2 data. This embodiment is a method of determining priority by considering at least one of a transmission mode and a type on which a D2D signal is based. Since the type 2B detection signal utilizes the resource designated by the network and transmits the detection signal, when the utilization of resources for this signal is preferentially required and also considering the transmission frequency of the detection signal itself, the type 2B detection The signal may be the D2D signal with the highest priority. Similarly, the SA of mode 1 may also have a high priority because it is a DCI based resource of the network.

In the fourth embodiment, in addition to the above-described embodiments, when a multi-carrier is configured in the UE, a D2D signal that is temporally earlier can be regarded as a higher priority. This method identifies the D2D resources set on the multicarrier and can prioritize based on this. The fourth embodiment may be considered optional.

The above-described first to fourth embodiments are not mutually exclusive methods, and a method according to any one of the embodiments may be used, or may be used in combination with each other. For example, the third embodiment and the second embodiment may be combined to derive the following priority order. For example, type 2B discovery Tx / Rx> mode 1 SA Tx / Rx> mode 1 data Tx / Rx> type 1 discovery Tx> mode 2 SA Tx> mode 2 data Tx> type 1 discovery Rx> mode 2 SA Rx> mode 2 < / RTI > data Rx.

What is meant here is that the conditions of one embodiment are considered to be the first of the four embodiments mentioned above and that the conditions of other embodiments may be considered if they are the same. Therefore, the terminal ultimately determines the priority between the D2D signals.

According to the method of the present invention described above, if a terminal has a single transceiver chain, a signal having a low priority can be dropped. This is also the case for a single carrier environment or a multi-carrier environment.

Alternatively, even if the terminal has an independent transceiver chain, the D2D signals on the multicarrier are generated at the same time, and the transmission power for the D2D signals is the total configured maximum output power (E.g., Tx power reduction) for the D2D signals based on the priority if the number of bits is greater than PCMAX. Power scaling refers to attenuating a certain percentage of the transmission power to allocate power so as not to exceed the total transmission power of the terminal. One example of power scaling is to multiply the original transmit power by a scaling factor. Power scaling can be expressed in various ways such as power regulation, power-scale down, and so on. That is, according to the present invention, power scaling can be selectively performed by classifying D2D signals based on priority.

15 is an example of a flowchart showing operations of a terminal according to the present invention.

Referring to FIG. 15, the terminal determines whether the D2D signals are collided (S1500). That is, it is set or scheduled to perform transmission / reception of a plurality of D2D signals in the same spectrum / subframe simultaneously to determine whether a collision occurs.

If there is a collision, the terminal determines a priority order of processing of the plurality of D2D signals (S1510). The terminal performs multiplexing by prioritizing which of the plurality of D2D signals to process (or transmit / receive) based on at least one of the first to fourth embodiments.

For example, according to the type of the D2D signal, priority can be determined in the order of, for example, the discovery signal> SA> data.

As another example, priority can be determined based on whether the D2D signal is a Tx signal or an Rx signal.

As another example, priorities can be determined based on at least one of the D2D communication mode and discovery type.

As another example, a temporally earlier D2D signal may be considered a higher priority. This may be the case when a multi-carrier is configured in the terminal.

If the collided D2D signal is the same for the priority considered first among the above examples, one of the other remaining examples may be considered. Therefore, the priorities considered above can be considered sequentially.

According to the determination, the high priority D2D signal selected based on the priority among the plurality of D2D signals is transmitted or received (S1520). Also, if D2D signals on multiple carriers occur at the same time and the transmit power for the D2D signals exceeds PCMAX, drop or power scaling is performed (selectively) on the D2D signals based on priority .

16 is an example showing a block diagram of a terminal according to the present invention.

16, the terminal 1600 includes a terminal transmission unit 1605, a terminal reception unit 1610, and a terminal processor 1620. The terminal may further include a memory (not shown). The memory is connected to the terminal processor 1620 and stores various information for driving the terminal processor 1620. In the above-described embodiments, the operation of the terminal 1600 can be implemented by the control of the terminal processor 1620. [ The terminal processor 1620 further includes a conflict determination unit 1625 and a multiplexing unit 1630.

The terminal transmitting unit 1605 transmits the D2D signal.

The terminal reception unit 1610 performs reception of the D2D signal.

The collision determiner 1625 determines whether or not a collision occurs by being set or scheduled so that transmission / reception of a plurality of D2D signals is simultaneously performed in the same spectrum / subframe.

The multiplexing unit 1630 determines a priority order in which to process (or transmit / receive) signals among a plurality of D2D signals in the corresponding spectrum / subframe based on at least one of the first to fourth embodiments, Multiplexing. The multiplexing unit 1630 may be referred to as a scheduling unit in scheduling a signal to be transmitted / received, may be referred to as a priority determining unit in order to determine a priority between D2D signals in which a collision occurs, May be referred to as a selection unit in terms of selecting which signal to process.

For example, the multiplexing unit 1630 may determine the priority of the D2D signals in which collision occurs in the order of the discovery signal> SA> data.

As another example, the multiplexing unit 1630 may determine the priority of the D2D signals in which the collision occurred based on whether the D2D signal is a Tx signal or an Rx signal.

As another example, the multiplexing unit 1630 may determine the priority of the D2D signals in which a collision has occurred based on at least one of the D2D communication mode and the discovery type.

As another example, the multiplexing unit 1630 may temporally prioritize the D2D signal with a higher priority. This may be the case when a multi-carrier is configured in the terminal 1600.

Meanwhile, the terminal processor 1620 may further include a power control unit (not shown). The power control unit determines whether or not the D2D signals on the multi-carrier are generated at the same time and the transmission power for the D2D signals exceeds P _CMAX . If the transmission power for the D2D signals exceeds P _CMAX , And (optionally) perform power scaling on the D2D signals.

The base station 1650 includes a base station receiver 1655, a base station transmitter 1660, and a base station processor 1670. The base station 1650 may further include a memory (not shown). The memory is coupled to the base station processor 1670 to store various information for driving the base station processor 1670. In the above-described embodiments, the operation of base station 1650 may be implemented by control of base station processor 1670. [ The base station processor 1670 may specifically include an RRC connection determination unit 1675, a D2D resource allocation unit 1680, and a D2D mode setting unit 1685.

The base station transmitting unit 1655 transmits the D2D setting information to the terminal 1600. [

The RRC connection determination unit 1675 can determine whether the terminal 1600 is in an idle mode or an RRC connection mode. The D2D mode setting unit 1685 can set the D2D mode of the terminal 1600. [

The D2D resource allocation unit 1680 may generate information on a resource pool for D2D communication based on whether the terminal 1600 is in an idle mode or an RRC connection mode. The D2D resource assignment unit 1680 also generates D2D setting information. The D2D setting information may include configuration information for D2D discovery type 1 / type 2, information about the corresponding Tx / Rx resource pool, and the like. The D2D setting information may include information on a D2D resource pool for D2D mode 2 / mode 1. The monitoring resource for the D2D discovery receipt may be set to a subset that is less than or equal to the D2D discovery resource pool. The D2D setting information may include information on a D2D monitoring interval (monitoring resource information). The monitoring resource information may include only information on a period for monitoring the D2D signals of the D2D terminals connected to the network of a single operator or may be a period for monitoring the D2D signals of the D2D terminals connected to the network of the single operator And information on the interval for monitoring the D2D signal of the D2D terminals connected to the networks of other operators.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (10)

In a terminal that performs inter-terminal communication (D2D) in a wireless communication system,
A transmitter configured to transmit a D2D signal;
A receiver configured to receive a D2D signal; And
And a control unit for controlling the transmitting unit and the receiving unit,
Wherein the control unit is configured to simultaneously transmit or receive a plurality of D2D signals in the same spectrum to determine whether a collision occurs; And
And a multiplexing unit for determining or scheduling a D2D signal to be transmitted or received in the spectrum in which the collision occurs based on the priority between the D2D signals. The method according to claim 1,
Wherein the multiplexing unit determines the priorities of the plurality of D2D signals in the order of the discovery signal>SA> data. The method according to claim 1,
Wherein the multiplexing unit determines a priority order of the plurality of D2D signals based on whether the signal is a transmission (Tx) signal or a reception (Rx) signal. The method according to claim 1,
Wherein the multiplexing unit determines a priority of the plurality of D2D signals based on at least one of a D2D communication mode and a discovery type. The method according to claim 1,
Wherein the multiplexing unit determines a temporally higher D2D signal among the plurality of D2D signals as a higher priority. A method of transmitting and receiving a D2D signal performed by a terminal in a wireless communication system,
Determining whether transmission or reception of a plurality of D2D signals in the same spectrum is performed simultaneously so that a collision occurs;
Determining a D2D signal to be transmitted or received in a spectrum in which the collision occurs based on a priority among the plurality of D2D signals; And
And transmitting or receiving the determined D2D signal. The method according to claim 6,
Wherein a priority among the plurality of D2D signals is set in the order of a discovery signal>SA> data. The method according to claim 6,
Wherein a priority between the plurality of D2D signals is set based on whether the signal is a transmission (Tx) signal or a reception (Rx) signal. The method according to claim 6,
Wherein a priority between the plurality of D2D signals is set based on at least one of a D2D communication mode and a discovery type. The method according to claim 6,
Wherein a priority between the plurality of D2D signals is set to be higher in time than a plurality of D2D signals.

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