WO2015020431A1

WO2015020431A1 - Device to device discovery method in wireless communication system

Info

Publication number: WO2015020431A1
Application number: PCT/KR2014/007276
Authority: WO
Inventors: 노태균; 이경석; 예충일; 안재영
Original assignee: 한국전자통신연구원
Priority date: 2013-08-08
Filing date: 2014-08-06
Publication date: 2015-02-12

Abstract

A device to device discovery method in a wireless communication system is disclosed. A device determines whether a first subframe for a physical layer uplink channel or a signal is the same as a second subframe for a discovery signal. At this time, when the first subframe and the second subframe are the same, the device transmits, in the same subframe, the physical layer uplink channel or the signal instead of transmitting or receiving the discovery signal.

Description

End-to-end discovery method in wireless communication system

The present invention relates to a method for discovery between terminals in a wireless communication system.

Recently, interest in device-to-device communication has been increasing to provide application services based on proximity, and various technologies for supporting communication between terminals have been proposed. 3GPP LTE also proposes various methods for communication between terminals.

In order to communicate between terminals, a terminal needs a procedure of discovering a counterpart terminal, and the terminal transmits a discovery signal to discover the counterpart terminal. Meanwhile, there is a need for a method of effectively transmitting such discovery signals.

The problem to be solved by the present invention is to provide an effective inter-terminal discovery method.

According to an embodiment of the present invention, a method for transmitting or receiving a discovery signal by a terminal is provided. The method may include determining whether a first subframe for a physical layer uplink channel or a signal and a second subframe for the discovery signal are the same, and the first subframe and the second subframe In the same subframe, transmitting the physical layer uplink channel or a signal without transmitting or receiving the signal may be included in the same subframe.

The first subframe may be a physical layer uplink data channel or a signal may be a subframe that transmits a physical layer uplink control channel.

The first subframe may be a subframe configured cell-specifically to transmit a sounding reference signal.

The first subframe may be a subframe including a resource region of a physical random access channel.

The terminal may be a terminal for transmitting the physical random access channel.

According to another embodiment of the present invention, a method may be provided in which a terminal transmits or receives a discovery signal. The method may include determining whether to transmit the physical random access channel in a subframe including a resource region of a physical random access channel, and not transmitting the physical random access channel in the subframe. If it is determined, the method may include transmitting or receiving the discovery signal in the remaining resources except for the resource region of the physical random access channel and the physical layer uplink control channel in the subframe.

The subframe may be a subframe other than a subframe configured for each cell to transmit a sounding reference signal, a subframe for transmitting a physical layer uplink data channel, or a subframe for transmitting the physical layer uplink control channel.

According to another embodiment of the present invention, a method for a terminal to transmit or receive a discovery signal may be provided. The method may include transmitting or receiving the discovery signal using at least one resource except the resource region without transmitting or receiving the discovery signal in a resource region of a physical random access channel.

According to another embodiment of the present invention, a method for a terminal to transmit or receive a discovery signal may be provided. The method may include: excluding a subframe including a physical layer uplink channel or a signal from a resource region that transmits or receives the discovery signal, and selects at least one resource from the excluded resource region. And transmitting or receiving the signal.

The subframe is a subframe configured to transmit a Physical Random Access Channel, a subframe configured cell-specifically or UE-specifically to transmit a scheduling request; A subframe configured for each cell or terminal to transmit a sounding reference signal, a subframe for transmitting a physical layer uplink control channel including an uplink / ack, and channel state information At least one of a subframe for transmitting a physical layer uplink control channel, and a subframe for transmitting a physical layer uplink data channel.

The uplink access point may be an uplink access point for a physical layer downlink data channel corresponding to initial transmission of downlink semi-persistent scheduling (SPS), and the uplink access point may include the physical layer uplink data channel. The transmitting subframe may be a subframe transmitting a physical layer uplink data channel corresponding to initial transmission or retransmission of the uplink Semi-Persistent Scheduling (SPS).

According to still another embodiment of the present invention, a method of transmitting a discovery signal to a plurality of terminals by a counterpart terminal is provided. The method may further include: dividing the plurality of terminals into groups including a first terminal group and a second terminal group, wherein the resource region used to transmit the discovery signal includes a first resource group and a second resource group. Dividing into groups, in a first period, the first terminal group transmitting the discovery signal using the first resource group; in the first period, the terminal second group is the second resource group Transmitting the discovery signal by using the second terminal group, transmitting the discovery signal by using the first resource group in the second period, and in the second period, the first terminal group And transmitting the discovery signal using the second resource group.

The first resource group may have a smaller amount of resources than the second resource group.

The dividing of the plurality of terminals may include dividing the plurality of terminals into a group including the first terminal group, the second terminal group, and a third terminal group. The method may include: In a first period and in the second period, the third terminal group transmits the discovery signal using the second resource group, and in a third period, the third terminal group uses the first resource group And transmitting the discovery signal, and in the third period, the first terminal group and the second terminal group may further include transmitting the discovery signal using the second resource.

The dividing of the plurality of terminals may include a step of a base station notifying the number of the groups to the plurality of terminals, and selecting a group of the plurality of terminals by using a hash function. .

The first resource group and the second resource group may be divided into time domains.

The time domain may be represented by an offset, a first period, a second week including a plurality of the first periods, and a variable including a bitmap.

The first resource group and the second resource group may be divided into frequency domains, and each resource group may be configured of physical resource block pairs.

The first period and the second period may correspond to the first period.

The first resource group and the second resource group may be resources except for a physical random access channel.

According to an embodiment of the present invention, it is possible to perform effective inter-device discovery in a wireless communication system.

1 is a diagram illustrating various environments in which discovery between terminals may occur according to an embodiment of the present invention.

2 is a diagram illustrating a connection relationship between discovery between terminals according to an embodiment of the present invention.

3 is a diagram illustrating a procedure of a first discovery method according to an embodiment of the present invention.

4 is a diagram illustrating a procedure of a second dispersal method according to an embodiment of the present invention.

5 illustrates a discovery resource region in a time domain according to an embodiment of the present invention.

6 is a diagram illustrating a method of allocating a discovery resource region to a plurality of groups according to an embodiment of the present invention.

7 illustrates a resource group A-resource group B according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating a simulation comparing a basic scheme with a method similar to an embodiment of the present invention.

9 illustrates multiplexing of a discovery resource region and a physical layer uplink channel according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating a case where a resource region set as a physical random access channel and a resource for transmitting or receiving a discovery signal overlap in a resource region as illustrated in FIG. 9.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, a device may be a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR-MS). Subscriber station (SS), portable subscriber station (PSS), access terminal (AT), user equipment (UE), machine type communication device (MTCD) ) May be included, and may include all or a part of functions of the UE, MT, AMS, HR-MS, SS, PSS, AT, UE, MTCD, and the like.

In addition, a base station (BS) may be an advanced base station (ABS), a high reliability base station (HR-BS), a node B (node B), an advanced node B (evolved node B, eNodeB), access point (AP), radio access station (RAS), base transceiver station (BTS), mobile multihop relay (MMR) -BS, relay serving as a base station station, RS), a high reliability relay (HR-RS) serving as a base station, etc., and may also refer to ABS, Node B, eNodeB, AP, RAS, BTS, MMR-BS, RS, HR. It may include all or part of functions such as -RS.

On the other hand, throughout the specification, the base station is used to mean a control device for controlling one cell. In a real communication system, a physical base station may control a plurality of cells, in which case the physical base station may include several base stations described in the specification. That is, it can be considered that each base station is assigned a different value for the parameter to be allocated differently for each cell.

In a wireless communication system, the terminals directly send and receive signals to each other, and the terminal may discover a counterpart terminal.

First, as shown in 110 of FIG. 1, discovery between terminals may occur when the terminals are all within network coverage. As shown in 130 of FIG. 1, discovery between terminals may occur when the terminals are all out of network coverage. Finally, as shown at 120 in FIG. 1, inter- terminal discovery may occur when some of the terminals are within network coverage and others are out of coverage (ie, couple network coverage).

The connection relationship of discovery between terminals may vary depending on the relationship between the terminal transmitting the discovery signal and the receiving terminal. In FIG. 2, 110 represents one-to-one discovery, 120 represents one-to-many discovery, and 130 represents many-to-one discovery.

The one-to-one discovery 110 represents a case in which one terminal transmits a discovery signal and one terminal receives a discovery signal. One-to-many discovery 120 represents a case where there are one terminal transmitting a discovery signal or a plurality of terminals receiving a discovery signal. In addition, the many-to-one discovery 130 represents a case where a plurality of terminals for transmitting a discovery signal and one terminal for receiving a discovery signal are present. Hereinafter, for convenience of description, the one-to-one discovery 110 will be described as a reference, but the present invention is not limited thereto. In case of one-to-many discovery, each terminal receiving the discovery signal may perform the same operation as the terminal receiving the discovery signal in one-to-one discovery. In addition, in the case of many-to-one discovery, each terminal transmitting the discovery signal may perform the same operation as the terminal transmitting the discovery signal in one-to-one discovery.

There may be two types of discovery between terminals depending on the subject that determines the discovery signal. The first discovery method is a case where a subject determines a discovery signal is a base station, and the second discovery method is a case where a subject determines a discovery signal is a terminal.

In FIG. 3, the first terminal 320 is a terminal for transmitting a discovery signal, and the second terminal 320 ′ is a terminal for receiving a discovery signal. Although the first terminal 320 may be a terminal belonging to the first base station 310 and the second terminal 320 'may be a terminal belonging to the second base station 310', the first terminal 320 and the second The terminal 320 'may belong to the same base station.

In FIG. 3, the subject that determines the discovery signal is assumed to be a base station. However, the subject that determines the discovery signal may not be the base station according to an environment to which discovery is applied. If the terminals are all outside the network coverage (network coverage of the base station), one of the terminals may be set as a coordinator. In this case, the coordinator may play the same role as the base station in FIG. 3. When some of the terminals are in network coverage and the others are out of network coverage (ie, in case of 120 of FIG. 1), one of the terminals existing in the network coverage may be selected as a relay node. In this case, the relay node may play the same role as the base station in FIG. 3. In other words, in the first discovery method, a subject that determines a discovery signal may be a base station or a terminal other than a terminal that transmits or receives a discovery signal.

As shown in FIG. 3, the first discovery method includes discovery request (S310), measurement request (S320), measurement report (S330), transmission allocation (S340), reception allocation (S350), discovery signal transmission (S360), and discovery. It may include the step of reporting (S370). Each step in FIG. 3 may not occur sequentially, and some steps may be omitted according to circumstances. As an example, in FIG. 3, the first terminal 320 transmits a discovery request. Unlike FIG. 3, the first base station 310 may transmit a reception assignment to the first terminal 320.

The first terminal may transmit a discovery request to the first base station 310 (S310). In FIG. 3, it is assumed that the first terminal 320 transmitting a discovery request transmits a discovery signal. However, the terminal transmitting the discovery request and the terminal transmitting the discovery signal may be different. For example, unlike FIG. 3, the second terminal 320 ′ may transmit a discovery request to the second base station 310 ′, and the first terminal 320 may transmit a discovery signal. Meanwhile, when the base station instructs discovery, the discovery request transmitted by the terminal may be omitted.

The discovery request may include information on the identifier of the terminal to be discovered. In addition, the discovery request may include information on whether open discovery or closed discovery.

The base station 310 may transmit a measurement request to the first terminal 320 (S320). In order to determine a physical resource to which the discovery signal is transmitted, a transmission format of the discovery signal, and the like, the first base station 310 transmits a measurement request to the first terminal 320. The measurement request may include information about physical resources to be measured.

Upon receiving the measurement request, the first terminal 320 may measure a corresponding physical resource according to the measurement request and transmit a measurement report to the first base station 310 (S330). The measurement report may include information about (preferred) physical resources suitable for transmitting the discovery signal. In addition, the measurement report may include information on (preferred) transmission power suitable for transmitting the discovery signal.

The first base station 310 may transmit a transmission allocation to the first terminal 320 (S340). The first terminal 320 transmits a discovery signal according to the transmission allocation. The transmission allocation information includes a discriminator for transmission transmission or reception allocation, a discriminator for periodic transmission or non-periodic transmission, an identifier for activation or deactivation for periodic transmission, and transmission for non-periodic transmission. Retrieval, scrambling code, physical resources, transmission format, and the like.

Meanwhile, the transmission allocation may be transmitted through a physical downlink control channel (PDCCH) or a physical downlink data channel (PDDCH). When the transmission allocation is transmitted through the physical layer downlink control channel (PDCCH), the terminal may transmit the reception success information to the base station. The terminal transmits reception success information to the base station only when the physical layer downlink control channel (PDCCH) is successfully demodulated.

In the case of periodic transmission, the identifier for activation or release may not be included in the transmission assignment. In this case, this identifier may be transmitted through a medium access control layer downlink control element.

The second base station 310 'may transmit a reception assignment to the second terminal 320' (S320 '). This reception assignment S320 'may be omitted. When the second terminal 320 'receives the reception assignment, the second terminal 320' receives the discovery signal. On the other hand, when the second terminal 320 'does not receive the reception allocation, the second terminal 320' performs blind demodulation on the discovery resource region to receive the discovery signal. Here, the base station 310 ′ may inform the terminal 320 ′ of the discovery resource region through system information. As one example, the system information may be a system information (SI) or a system information block (SIB) in 3GPP LTE.

The reception allocation information includes a discriminator for transmission allocation or reception allocation, a discriminator for periodic transmission or aperiodic transmission, an identifier for activation or deactivation for periodic transmission, the number of transmissions for aperiodic transmission, It may include a scrambling code, a physical resource, a transmission format, and the like.

Meanwhile, the reception allocation may be transmitted through a physical downlink control channel (PDCCH) or a physical downlink data channel (PDDCH). When the transmission allocation is transmitted through the physical layer downlink control channel (PDCCH), the terminal may transmit the reception success information to the base station. The terminal transmits reception success information to the base station only when the physical layer downlink control channel (PDCCH) is successfully demodulated.

In the case of periodic transmission, the identifier of whether it is activated or released may not be included in the reception assignment. In this case, this identifier may be transmitted through a medium access control layer downlink control element.

The second terminal 320 ′ receiving the discovery signal may transmit a discovery report (S370). Meanwhile, the second terminal 320 ′ may not transmit a discovery report. When the second terminal 320 'transmits the discovery report, the second terminal 320' may transmit the discovery report to the second base station 310 'or the first terminal 310'. The discovery report may include a discovery identifier, a received power of the discovery signal, a transmission delay of the discovery signal, and the like.

In FIG. 4, the first terminal 420 is a terminal for transmitting a discovery signal, and the second terminal 420 ′ is a terminal for receiving a discovery signal. In the second discovery method, the terminal transmitting the discovery signal determines a physical resource, a transmission format, a transmission power, and the like of the discovery signal. In the second discovery scheme, the discovery signal may be selected and transmitted from the discovery resource region. The information about the discovery resource region may be owned by the first terminal 420 and the second terminal 420 '. In addition, in the discovery resource region, the base station may inform the first terminal 420 and the second terminal 420 'of the system information in advance. The first terminal 420 selects one of the discovery resource regions and transmits a discovery signal (S410). The second terminal 420 'performs blind demodulation on the discovery resource region to receive the discovery signal. A detailed description of the discovery resource region is described in more detail below.

As the method for the first terminal 420 to select one of the discovery resource regions, the following scheme may be used. The first way is to do random selection. The second way is to use a hash function. The input of the hash function may be an identifier of a terminal, an identifier of a cell, or a combination of an identifier of a terminal and an identifier of a cell. As one example, the identifier of the terminal may be a Cell-Radio Network Temporary Identifier (C-RNTI), an International Mobile Subscriber Identity (IMSI), or a SAE Temporary Mobile Subscriber Identity (S-TMSI) in 3GPP LTE. When the terminal is in the RRC_CONNECTED state, C-RNTI, IMSI or S-TMSI may be used, and when the terminal is in the RRC_IDLE state, IMSI or M-TMSI may be used. Meanwhile, the identifier of the cell may be a physical cell ID or a virtual cell ID in 3GPP LTE. The third approach is to choose based on physical measurements.

After receiving the discovery signal, the second terminal 420 ′ may transmit a discovery report (S420). Meanwhile, the second terminal 420 ′ may not transmit the discovery report. When the second terminal 420 'transmits the discovery report, the second terminal 420' may transmit the discovery report to the first terminal 420 or the base station to which the second terminal 420 'belongs. The discovery report may include a discovery identifier, a received power of the discovery signal, a transmission delay of the discovery signal, and the like.

Hereinafter, a discovery resource region according to an embodiment of the present invention will be described. In the following description, a resource set to which a discovery signal can be transmitted is defined as a discovery resource region (DRR). The discovery resource region is composed of a time domain and a frequency domain.

First, the discovery resource region of the time domain may be represented by one or a plurality of variable sets. Variables constituting each variable set may include an offset, a first period, a second period, a bitmap, and the like.

5 illustrates a discovery resource region in a time domain according to an embodiment of the present invention. As shown in FIG. 5, the discovery resource region of the time domain is represented by one variable set.

First, the offset indicates the position where the bitmap starts based on the value 0 of the system frame number (SFN). The offset value may have a value from 0 to a first period or from 0 to a second period. The unit represented by the offset value may be a subframe or a frame. On the other hand, as an example of the subframe may be a resource unit indicating a time interval of 1ms in 3GPPP LTE, as an example of a frame may be a resource unit indicating a time interval of 10ms in 3GPPP LTE.

The length of the bitmap may range from 1 to the value of the first period. Each bit of the bitmap represents a subframe. Through a bitmap value of 0 or 1, it is possible to distinguish whether or not the corresponding subframe is a discovery resource region of the time domain. If the discovery resource region of the time domain is composed of discontinuous subframes, the bitmap scheme is useful. On the other hand, when the discovery resource region of the time domain consists of consecutive subframes, only the length of the continuous subframe needs to be known. Therefore, a length representing the number of consecutive subframes, not a bitmap, may be used as a variable constituting each wall number set.

As shown in FIG. 5, the same bitmap is repeatedly displayed during the second period in units of the first period. In other words, the same bitmap is repeated by a value obtained by dividing the second period by the first period during the second period. And, the bitmap during the next second period may be the same as or different from the bitmap during the previous second period. The unit of the value of the first period may be a subframe or a frame, and the unit of the value of the second period may be a frame.

On the other hand, when there are a plurality of sets of variables representing the discovery resource region of the time domain, 'variant inclusion', which is a variable representing inclusion or exclusion, may be further included in each variable set. As an example, when the discovery resource region of the time domain is represented by two variable sets, it may be assumed that the inclusion of the first variable set is included and the inclusion of the second variable set is excluded. . In this case, the discovery resource region of the time domain includes the region indicated by the first variable set and excludes the region represented by the second variable set. When there are a plurality of variable sets representing the discovery resource areas of the time domain, each variable set may not include 'not included' described above. In this case, the discovery resource region of the time domain may consist of a sum set of regions represented by each variable set.

The discovery resource region of the frequency domain may be represented as a bitmap in units of physical resource block pairs for the entire system bandwidth. Meanwhile, the discovery resource region of the frequency domain may be represented by one or a plurality of resource allocation schemes. Examples of the resource allocation scheme include an uplink resource allocation type 0 or an uplink resource allocation scheme in 3GPP LTE. It may be 1 (uplink resource allocation type 2). When the discovery resource region of the frequency domain is represented by a plurality of resource allocation schemes, each resource allocation scheme may be the same or different. When using different allocation schemes, a resource allocation scheme distinguisher may be included to distinguish the resource allocation schemes. When the discovery resource region of the frequency domain is represented by a plurality of resource allocation schemes, 'inclusion', which is a variable representing inclusion or exclusion, may be additionally included. Here, 'include' plays the same role as 'include', which is a variable included in the discovery resource region of the time domain described above. On the other hand, when the resource region of the frequency domain is represented by a plurality of resource allocation schemes, the above 'not included' may not be included. In this case, the discovery resource region of the frequency domain may be composed of a union of regions indicated by each resource allocation scheme.

The discovery resource region of the frequency domain is for one subframe, but the discovery resource region of the same frequency region may be used during the second period. The discovery resource region of the frequency domain during the next second period may be the same as or different from the discovery resource region of the frequency domain during the previous second period.

When the discovery resource region informed by the base station and the resource region of the physical random access channel (PRACH) overlap each other, the overlapping region may be excluded from the discovery resource region. Here, the physical random access channel (PRACH) resource region may refer to the physical random access channel (PRACH) resource region for the serving cell, and refers to the union of the physical random access channel (PRACH) resource region of the serving cell and the neighbor cell. You may. To this end, the base station may inform the terminal of the physical random access channel (PRACH) resource region of the neighbor cell. The relationship between the discovery resource region and the physical random access channel (PRACH) resource region will be described in more detail with reference to FIG. 10 below.

The base station may inform the terminal of the discovery resource region, which may be one or a plurality of discovery resource regions. In one embodiment, the base station may inform the UE of the discovery resource region of the serving cell and the discovery resource region of the neighboring cell. Here, the discovery resource region of the serving cell and the discovery resource region of the neighboring cell may be the same or different. In addition, the discovery resource region of the neighbor cell may be the same or different for each neighbor cell. In another embodiment, the base station may inform the terminal of the discovery resource region of the open discovery and the restricted discovery resource region. Here, the discovery resource region of the open discovery and the discovery resource region of the closed discovery may be the same or different. In addition, open discovery or closed discovery may use one or a plurality of discovery resource regions according to each detailed grouping. In another embodiment, the base station may inform the UE of the discovery resource region used for the discovery request and the discovery resource region used for the discovery response. Here, the discovery resource region used for the discovery request and the discovery resource region used for the discovery response may be the same or different. In another embodiment, the base station may inform the terminal of the discovery resource region of the Radio Resource Control_IDLE (RRC_IDLE) terminal and the discovery resource region of the Radio Resource Control_CONNECTED (RRC_CONNECTED) terminal. Here, the discovery resource region of the RRC_IDLE terminal and the discovery resource region of the RRC_CONNECTED terminal may be the same or different. RRC_CONNECTED A discovery resource through which a UE transmits a discovery signal may be allocated to each UE. The discovery resources are allocated to each terminal in a semi-persistent allocation method and a dynamic allocation method. Discovery resources used by the RRC_CONNECTED terminal may be quasi-statically allocated. That is, the terminal may transmit a discovery signal a plurality of times to this discovery resource. In addition, discovery resources used by the RRC_CONNECTED terminal may be dynamically allocated. That is, the terminal transmits the discovery signal once from the discovery resource, and the discovery resource is allocated every time the terminal transmits the discovery signal. In addition, discovery resources through which the RRC_CONNECTED terminal transmits a discovery signal may not be allocated to each terminal. That is, the RRC_CONNECTED terminal may select a resource to transmit its own discovery signal from the discovery resource region. The discovery resource through which the RRC_IDLE terminal transmits a discovery signal may not be allocated for each terminal. That is, the RRC_IDLE terminal may select a resource to transmit its own discovery signal from the discovery resource region.

The base station may inform the terminal of the discovery resource region may include system information, RRC (Radio Resource Control) signaling, or a combination of system information and RRC signaling. The system information is a method in which a base station broadcasts a discovery resource region to all terminals in a cell. RRC signaling is a method in which a base station individually transmits a discovery resource region to each terminal in a cell. When a combination of system information and RRC signaling is used, a discovery resource region common to all terminals in a cell is informed to the terminal through system information, and a discovery resource region that is not common to all terminals in the cell is determined by the base station through RRC signaling. Inform the terminal.

Meanwhile, the discovery resource region may change with time. When the base station informs the terminal of the discovery resource region through the system information, the base station can inform the terminal whether or not the discovery resource region has changed. In one embodiment, in 3GPP LTE, whether the discovery resource region is changed or not, the base station may inform the terminal through sytemInfoValueTag of the SIB1 or sytemInfoModification of the paging message.

A plurality of discovery resources exist in the discovery resource region. As described above, the discovery resource may be selected by a terminal transmitting a discovery signal from one discovery resource region or may be directly informed by the base station to the terminal. Here, the base station directly informs the discovery resource by informing the terminal of the discovery resource index. When the base station informs the terminal of one discovery resource region, the base station informs the terminal of the discovery resource index. Meanwhile, when the base station informs the terminal of the plurality of discovery resource regions, the base station informs the terminal of the index of the discovery resource region and the discovery resource index in the discovery resource region.

The base station may use RRC (Radio Resource Control) signaling as a method of informing the terminal of the discovery resource. The base station may inform one UE of a discovery resource through RRC signaling. As another method, the base station informs the terminal of a plurality of discovery resources through RRC signaling, and the terminal can select one of the plurality of discovery resources. In this method, the terminal receiving the discovery signal performs blind demodulation on all of the plurality of resources indicated by the base station through RRC signaling to find the discovery signal.

As another method of informing the base station of the discovery resource, the base station informs the terminal of a plurality of discovery resources through RRC signaling. Here, the base station informs the user equipment of one of the plurality of discovery resources through a MAC Control Element (PCE), a Physical Downlink Control Channel (PDCCH), or an Enhanced Physical Downlink Control Channel (EPDCCH).

When the base station informs the UE of the discovery resource, a transceiver may be included. In this case, the UE may distinguish whether to transmit or receive a discovery signal through the corresponding discovery resource.

The terminal transmitting the discovery signal transmits the discovery signal using the discovery resource known through the above method, and the terminal receiving the discovery signal demodulates the discovery signal using the known discovery resource through the above method. The method of notifying the discovery resource to the terminal transmitting the discovery signal and the method of notifying the discovery resource to the terminal receiving the discovery signal may be the same or different. Meanwhile, the base station may inform the discovery resource to the terminal transmitting the discovery signal, and may not inform the discovery resource to the terminal receiving the discovery signal. In this case, the terminal receiving the discovery signal performs blind demodulation on all discovery resources in one or a plurality of discovery resource regions.

The base station informs the terminal of the discovery resource region, and the terminal may select one discovery resource from the discovery resource region and transmit a discovery signal. When the base station informs the terminal of the plurality of discovery resource regions, operations of the terminal transmitting the discovery signal and the terminal receiving the discovery signal may be different. When the base station informs the terminal of the discovery resource region of the serving cell and the discovery resource region of the neighboring cell, the terminal transmitting the discovery signal selects one discovery resource from the discovery resource region of the serving cell and transmits the discovery signal. Meanwhile, the terminal receiving the discovery signal performs blind demodulation on the discovery resource region of the serving cell as well as the discovery resource region of the serving cell. In addition, when the base station informs the terminal of the discovery resource region of the RRC_IDLE terminal and the discovery resource region of the RRC_CONNECTED terminal, the terminal transmitting the discovery signal according to its state (ie, RRC_IDLE or RRC_CONNECTD) of one of the corresponding discovery resource regions The discovery resource is selected to transmit a discovery signal. Meanwhile, the terminal receiving the discovery signal performs blind demodulation on the discovery resource region of RRC_CONNECTD as well as the discovery resource region of RRC_IDLE.

The UE may randomly select one discovery resource in the discovery resource region and transmit a discovery signal. The terminal may arbitrarily select the entire discovery resource region or may randomly select a specific subframe among the discovery resource regions. Meanwhile, the UE may randomly select the entire resource group A or the entire resource group B, or may randomly select a specific subframe among the resource group A or the resource group B. FIG. Specific subframes may be excluded from the discovery resource region for smooth operation of the cellular link. Otherwise, transmitting or receiving the discovery signal may interfere with the operation of the cellular link. Resource group A or resource group B will be described in more detail below. In this case, the specific subframe is a cell-specifically configured subframe configured to transmit a physical random access channel (PRACH) and a scheduling request (SR) so that a terminal transmitting a discovery signal can transmit a physical random access channel (PRACH). Or a subframe configured UE-specifically, a subframe configured cell-specifically or UE-specifically to transmit a sounding reference signal, Subframe for transmitting a physical layer uplink control channel including uplink A / N (Ack / Nack), Subframe for transmitting a physical layer uplink control channel including periodic channel state information (CSI) All or part of a frame, a subframe that transmits a physical layer uplink data channel, and the like may be configured. Here, the uplink A / N may be more specifically an uplink A / N (Ack / Nack) for a physical layer downlink data channel corresponding to initial transmission of downlink semi-persistent scheduling (SPS). Can be. The subframe transmitting the physical layer uplink data channel may be more specifically a subframe transmitting the physical layer uplink data channel corresponding to the initial transmission or retransmission of the uplink SPS.

The discovery resource region may be divided into two groups that do not overlap each other. One is resource group A and the other is resource group B. Resource group A may occupy relatively fewer discovery resources than resource group B.

The terminals of each cell may be divided into Ng terminal groups. The base station may explicitly inform the terminal of the number of groups Ng. In addition, the base station may implicitly inform Ng of the second period and the first period, which are variables representing the resource region of the time domain, to the terminal. In one embodiment, Ng may be a value obtained by dividing the second period by the first period. When the base station explicitly or implicitly informs the Ng to the terminal, the base station may include the Ng in the system information and transmit the Ng to the terminal.

The terminal may select a group of terminals through random selection. In addition, the terminal may select a terminal group through a hash function. The input of the hash function may be an identifier of a terminal, an identifier of a cell, or a combination of an identifier of a terminal and an identifier of a cell. As one example, the identifier of the terminal may be a Cell-Radio Network Temporary Identifier (C-RNTI), an International Mobile Subscriber Identity (IMSI), or a SAE Temporary Mobile Subscriber Identity (S-TMSI) in 3GPP LTE. When the terminal is in the RRC_CONNECTED state, C-RNTI, IMSI or S-TMSI may be used, and when the terminal is in the RRC_IDLE state, IMSI or M-TMSI may be used. Meanwhile, the identifier of the cell may be a physical cell ID or a virtual cell ID in 3GPP LTE.

In one first period, terminals belonging to one terminal group transmit a discovery signal using a resource group A, and terminals belonging to the other group transmit a discovery signal using a resource group B. FIG. In the next first period, terminals belonging to different terminal groups transmit a discovery signal using resource group A. FIG.

6 is a diagram illustrating a method of allocating a discovery resource region to a plurality of groups according to an embodiment of the present invention. FIG. 6 assumes that Ng is 3, Resource group A occupies NsA subframes, and Resource group B occupies NsB (= Ns-NsA) subframes. Ns refers to the total number of subframes in one discovery resource region (DDR).

In a first first period 610, terminals belonging to the first terminal group transmit a discovery signal using resource group A, and terminals belonging to the remaining groups (second and third terminal groups) using resource group B. Transmit a discovery signal.

In a second first period 620, terminals belonging to the second terminal group transmit resource discovery signals using resource group A, and terminals belonging to the remaining groups (first and third terminal groups) using resource group B. Transmit a discovery signal.

In a third first period 630, terminals belonging to the third terminal group transmit resource discovery signals using resource group A, and belong to the remaining groups (first and second terminal groups) using resource group B. The terminals transmit a discovery signal.

In FIG. 6, Ng = 3 and resource group A and resource group B are assumed to exist explicitly. However, in the discovery resource region, one of resource group A and resource group B is explicitly present and the other is implicitly. May exist. In this case, only terminals of the terminal groups belonging to the explicit resource group transmit the discovery signal, and terminals of the terminal groups belonging to the implicit resource group do not transmit the discovery signal. In one embodiment, resource group A may be explicitly present and resource group B may be implicitly present. In this case, only the terminals belonging to the first terminal group transmit the discovery signal in the first first period, and only the terminals belonging to the second terminal group transmit the discovery signal in the second first period. In the third first period, only terminals belonging to the third terminal group transmit a discovery signal. In another embodiment, resource group B may be explicitly present and resource group A may be implicitly present. In this case, only terminals belonging to the other group except the terminals belonging to the first terminal group in the first first period transmit discovery signals, and belonging to the remaining group except the terminals belonging to the second terminal group in the second first period. Only terminals transmit a discovery signal. In the third first period, only the terminals belonging to the other group except the terminals belonging to the third terminal group transmit the discovery signal. In FIG. 6, the second period is illustrated, but the second period may be omitted. In this case, in a specific first period, the terminal group for transmitting the discovery signal using the resource group A may be determined as follows. According to an embodiment, the terminal group for transmitting the discovery signal using the resource group A may be determined according to the modulo operation of the color days of the first period.

Resource group A and resource group B may be determined as follows. The discovery resource region may be divided into a plurality of resource groups that do not overlap each other. Each resource group may be distinguished from each other in a time domain. In this case, each resource group may be composed of contiguous subframes or may be composed of discontinuous subframes. Meanwhile, each resource group may be distinguished from each other in a frequency domain. In this case, each resource group may be composed of consecutive physical resource block pairs (PRB-pairs) and non-contiguous physical resource block pairs. It may consist of. In addition, each resource group may be distinguished from each other by a combination of a time domain and a frequency domain.

The first way to determine resource group A and resource group B is to divide the discovery resource area into Ng resource groups, resource group A consists of one of Ng resource groups, and resource group B contains Ng-1 resources. It is organized into groups. The second method divides the discovery resource region into two resource groups, and resource group A is composed of NsA subframes, NprbA physical resource block pairs or NsA subframes and NsprA physical resource block pairs among the discovery resource regions. Group B is composed of resources other than resource group A of discovery resources.

Depending on the type of resource group constituting resource group A and resource group B, there may be a maximum of Ng resource group A-resource group B patterns. In one cell, the resource group A-resource group B pattern may be identical and may use Ng different resource group A-resource group B patterns according to the first period index. In addition, even between different cells, each cell may use the same resource group A-resource group B pattern, and each cell may use a different resource group A-resource group B pattern according to a physical cell identifier or a virtual cell identifier. 7 illustrates a resource group A-resource group B according to an embodiment of the present invention, wherein three resource groups are divided into time domains. In FIG. 7, it is assumed that different cell group A-resource group B patterns are used for each cell, and that different cell group A-resource group B patterns are also used for each cell.

FIG. 8 is a diagram illustrating a simulation comparing a basic scheme with a method similar to an embodiment of the present invention. The basic scheme is a random selection method (represented as Basic in FIG. 8) without considering the terminal and the resource group. The same method as the embodiment of the present invention is a random selection method considering the terminal and the resource group as shown in FIG. 6. (Indicated by Modified 1, 2, 3 in FIG. 8).

In FIG. 8, it is assumed that Ns = 16, and the remaining conditions are shown in Table 1 below. As shown in FIG. 8, it can be seen that the method according to the embodiment of the present invention has a larger average number of UEs discovered than the basic method. Further, as the number of NsA (resource allocated to resource group A) is smaller and the number of resource groups Ng is smaller (Modified 1 in FIG. 8), more terminals can be found. In addition, by adjusting Ng and NsA, it is possible to support discovery services of various terminals requiring different capabilities.

Table 1

The discovery resource region may be located in part of a resource for transmitting an uplink channel. 9 illustrates multiplexing of a discovery resource region and a physical layer uplink channel according to an embodiment of the present invention.

As illustrated in FIG. 9, the base station may multiplex a subframe in which the discovery resource region and the physical layer uplink data channel are transmitted in the time domain. In addition, the base station may multiplex the physical resource block pairs through which the discovery resource region and the physical layer uplink control channel are transmitted in the frequency domain. In FIG. 9, the physical layer uplink control channel may be a physical uplink control channel (PUCCH), and the physical layer uplink data channel may be a physical uplink shared channel (PUSCH). 9 illustrates an embodiment of a discovery resource region, where the discovery resource region occupies a temporally continuous subframe, and the discovery resource region may occupy a discontinuous subframe temporally.

When the terminal transmits a physical layer uplink channel or a physical layer uplink signal, there may be a restriction on transmission and reception of a discovery signal in order for the cellular link to operate smoothly. In a subframe in which a terminal transmits a physical layer uplink data channel or a physical layer uplink control channel, the terminal transmits a physical layer uplink data channel or a physical layer uplink control channel without transmitting or receiving a discovery signal. In addition, in a subframe configured cell-specifically so that the terminal transmits a sounding reference signal, the terminal does not transmit or receive a discovery signal. In other words, the UE determines whether the subframe for the discovery signal and the subframe for the physical layer uplink channel or the physical layer uplink signal collide with each other, and if they collide with each other, do not transmit or receive the discovery signal in the corresponding subframe. It transmits a physical layer uplink channel or a physical layer uplink signal. Here, the subframe for the physical layer uplink channel or the physical layer uplink signal is a subframe for transmitting the physical layer uplink data channel (PUSCH) described above, a subframe for transmitting the physical layer uplink control channel (PUCCH). Or a subframe configured cell-specifically to transmit a sounding reference signal and a subframe including a resource region 1000 configured as a physical random access channel described below.

The physical random access channel (PRACH) may occupy a part of a resource region through which physical layer uplink data is transmitted. Accordingly, the resource region 1000 configured as the physical random access channel as shown in FIG. 10 may overlap with a resource for transmitting or receiving a discovery signal. A terminal transmitting a physical random access channel in a subframe 1100 including a resource region 1000 set as a physical random access channel is a terminal in a subframe 1100 including a resource region 1000 set as a physical random access channel. Do not send or receive discovery signals. On the other hand, a terminal that does not transmit the physical random access channel in the subframe 1100 including the resource region 1000 set as the physical random access channel transmits or detects a discovery signal in the resource region 1000 set as the physical random access channel. Do not receive In other words, in the resource region 1000 configured as the physical random access channel, the terminal does not transmit or receive a discovery signal regardless of whether the terminal transmits or does not transmit the physical random access channel. By doing so, the UE can transmit the physical random access channel without being interrupted by the transmission and reception of the discovery signal. The base station can also receive the physical random access channel without being interrupted by the discovery signal.

Meanwhile, a terminal that does not transmit a physical random access channel in a subframe 1100 including a resource region 1000 set as a physical random access channel may have a resource region 1000 set as a physical random access channel in this subframe 1100. The discovery signal may be transmitted or received in the remaining resources 1200 except for the resource region through which the physical layer uplink control channel is transmitted. A subframe configured cell-specifically to transmit a sounding reference signal in the subframe 1100 in which the UE can transmit or receive a discovery signal may be excluded. Also, in the subframe 1100 in which the terminal may transmit or receive a discovery signal, a subframe in which the terminal transmits a physical layer uplink data channel, a physical layer uplink control channel, or a physical random access channel may be excluded.

Meanwhile, the terminal may support simultaneous transmission of a discovery signal and a physical layer uplink. In this case, the terminal may transmit the discovery signal and the physical layer uplink in the same subframe, respectively. The terminal may inform whether the base station supports simultaneous transmission of a discovery signal and a physical layer uplink through RRC signaling. In addition, the base station may inform the terminal whether to allow the simultaneous transmission of the discovery signal and the physical layer uplink through RRC signaling. Here, the physical layer uplink is a physical layer uplink channel or a physical layer uplink signal or a physical layer It may be an uplink channel and a physical layer uplink signal.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

The present invention can be used in a wireless communication system.

Claims

A method for transmitting or receiving a discovery signal by a terminal,

Determining whether a first subframe for a physical layer uplink channel or signal and a second subframe for the discovery signal are the same; and

If the first subframe and the second subframe are equal to each other, transmitting the physical layer uplink channel or signal in the same subframe without transmitting or receiving the discovery signal.
The method of claim 1,

Wherein the first subframe is a physical layer uplink data channel or a signal is a subframe that transmits a physical layer uplink control channel.
The method of claim 1,

Wherein the first subframe is a cell-specifically configured subframe to transmit a sounding reference signal.
The method of claim 1,

The first subframe is a subframe including a resource region of a physical random access channel.
The method of claim 4, wherein

The terminal is a terminal for transmitting the physical random access channel.
A method for transmitting or receiving a discovery signal by a terminal,

Determining whether to transmit the physical random access channel in a subframe including a resource region of a physical random access channel; and

When it is determined that the physical random access channel is not transmitted in the subframe, the discovery signal is transmitted or received in the remaining resources except for the resource region of the physical random access channel and a physical layer uplink control channel in the subframe. Method comprising the steps.
The method of claim 6,

The subframe is a subframe other than a subframe configured for each cell to transmit a sounding reference signal, a subframe for transmitting a physical layer uplink data channel, or a subframe for transmitting the physical layer uplink control channel.
A method for transmitting or receiving a discovery signal by a terminal,

And not transmitting or receiving the discovery signal in a resource region of a physical random access channel, and transmitting or receiving the discovery signal using at least one resource except for the resource region.
A method for transmitting or receiving a discovery signal by a terminal,

Excluding a subframe including a physical layer uplink channel or a signal from a resource region for transmitting or receiving the discovery signal, and

Selecting at least one of the excluded resource regions to transmit or receive the discovery signal.
The method of claim 9,

The subframe is a subframe configured to transmit a Physical Random Access Channel, a subframe configured cell-specifically or UE-specifically to transmit a scheduling request; A subframe configured for each cell or terminal to transmit a sounding reference signal, a subframe for transmitting a physical layer uplink control channel including an uplink / ack, and channel state information At least one of a subframe for transmitting a physical layer uplink control channel, and a subframe for transmitting a physical layer uplink data channel.
The method of claim 10,

The uplink access / access is an uplink access / access for a physical layer downlink data channel corresponding to initial transmission of downlink semi-persistent scheduling (SPS),

The subframe transmitting the physical layer uplink data channel is a subframe transmitting a physical layer uplink data channel corresponding to initial transmission or retransmission of a semi-persistent scheduling (SPS). Way.
A method of transmitting a discovery signal by a plurality of terminals to a counterpart terminal,

Dividing the plurality of terminals into groups including a first terminal group and a second terminal group;

Dividing a resource region used to transmit the discovery signal into a group including a first resource group and a second resource group;

Transmitting, by the first terminal group, the discovery signal using the first resource group in a first period,

In the first period, transmitting, by the terminal second group, the discovery signal using the second resource group;

In a second period, the second terminal group transmitting the discovery signal using the first resource group, and

In the second period, the first terminal group transmitting the discovery signal using the second resource group.
The method of claim 12,

And wherein the first resource group has less resource than the second resource group.
The method of claim 12,

The dividing of the plurality of terminals may include dividing the plurality of terminals into groups including the first terminal group, the second terminal group, and a third terminal group.

In the first period and the second period, the third terminal group transmitting the discovery signal using the second resource group;

In a third period, the third terminal group transmits the discovery signal using the first resource group, and

And in the third period, the first terminal group and the second terminal group further comprise transmitting the discovery signal using the second resource.
The method of claim 12,

The step of dividing the plurality of terminals,

The base station notifying the plurality of terminals of the number of groups; and

And selecting a group of the plurality of terminals, respectively, by using a hash function.
The method of claim 12,

And the first resource group and the second resource group are divided into time domains.
The method of claim 16,

The time domain is represented by a variable comprising an offset, a first period, a second week comprising a plurality of the first periods, and a bitmap.
The method of claim 17,

And the first resource group and the second resource group are divided into frequency domains, each resource group consisting of physical resource block pairs.
The method of claim 17,

Wherein the first period and the second period correspond to the first period.
The method of claim 12,

And the first resource group and the second resource group are resources except for a physical random access channel.