KR102366259B1 - Method and apparatus for transmitting and receiving discovery signal of device to device communications - Google Patents

Abstract

The present disclosure relates to a 5G or pre-5G communication system to be provided to support a higher data rate after a 4G communication system such as LTE. The present disclosure relates to a method and apparatus for transmitting a signal for D2D communication. The terminal receives system information including transmit power parameters for D2D transmission on a non-serving carrier by a terminal located in a serving cell providing a serving carrier, and uses the transmit power parameters to transmit power for D2D transmission , and transmits the D2D signal through the non-serving carrier with the determined transmission power. The base station generates system information including transmission power parameters for D2D transmission on a non-serving carrier, and transmits the system information to a terminal located in a serving cell providing a serving carrier.

Description

DISCOVERY SIGNAL OF DEVICE TO DEVICE COMMUNICATIONS

The present invention relates to a method and apparatus for transmitting and receiving a discovery signal for device-to-device (D2D) communication.

Efforts are being made to develop an improved 5G (5 ^th -Generation) communication system or pre-5G communication system to meet the increasing demand for wireless data traffic after commercialization of the 4G (4 ^th -Generation) communication system. . For this reason, the 5G communication system or the pre-5G communication system is called a system after the 4G network (Beyond 4G Network) communication system or after the LTE system (Post LTE).

In order to achieve a high data rate, the 5G communication system is being considered for implementation in a very high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the propagation distance of radio waves, in the 5G communication system, beamforming, massive multi-input multi-output (massive MIMO), and all-dimensional multiple input/output are used. (Full Dimensional MIMO: FD-MIMO), array antenna (array antenna), analog beam-forming (analog beam-forming), and large-scale antenna (large scale antenna) technologies are being discussed.

In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud radio access network: cloud RAN), an ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation Technology development is underway.

In addition, in the 5G system, FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), which are advanced coding modulation (Advanced Coding Modulation: ACM) methods, and FBMC (Filter Bank Multi Carrier), NOMA, which are advanced access technologies, (non orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

Due to the recent spread of smartphones, data traffic is rapidly increasing. As the number of smartphone users increases, application services such as SNS (Social Network Service) and games that can be used on smartphones are becoming more active. . In particular, the amount of traffic is expected to increase to the extent that it is difficult for base stations to handle when the new mobile market, human-to-object communication, and object-to-object intelligence communication that utilizes objects, is activated beyond human-to-human communication.

As one of the technologies that can solve these problems, a direct communication technology between terminals has recently attracted attention. This technology, called D2D (Device to Device) communication, is attracting attention in both licensed bands of mobile communication and unlicensed bands such as wireless local area networks (WLANs).

D2D communication technology based on 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) may be classified into D2D discovery and D2D communication. In the inter-terminal search, one terminal identifies the identities or interests of other terminals existing in its proximity, or a series of informing other terminals of its identity or interest in proximity. means the procedure. In this case, the identity and interest may be an identifier (ID) of the terminal, an application identifier, or a service identifier, and may be variously configured according to a D2D service and an operation scenario.

Inter-terminal search operations being studied in the existing technology are based on an environment in which the serving cell of the terminal is configured with a single frequency. In addition, in the existing technology, D2D transmission was performed only on a serving carrier, which is a frequency used by a serving cell. Accordingly, there is a need for an operation and procedure for transmitting a D2D discovery signal through a non-serving carrier, which is a frequency not used by the serving cell.

Meanwhile, in LTE, carrier aggregation (CA) technology may be supported in order to increase the efficiency of cellular frequency resources and increase data rates. In CA, a serving cell may be configured with a multi-carrier, and may simultaneously perform reception and transmission on different frequencies. Therefore, operations and procedures necessary to apply CA in a cellular-based D2D system are also required.

The present invention provides a method and apparatus for transmitting and receiving a signal for communication between terminals.

The present invention provides a method and apparatus for transmitting a D2D discovery signal on a frequency not used by a serving cell.

The present invention provides a method and apparatus for a base station and a terminal for supporting transmission of a D2D discovery signal on a non-serving carrier.

The present invention provides a method and apparatus for applying CA in a cellular-based D2D system.

A method according to an embodiment of the present invention includes; A signal transmission method for terminal-to-device (D2D) communication, comprising: a terminal located in a serving cell providing a serving carrier receiving system information including transmission power parameters for D2D transmission in a non-serving carrier; determining a transmit power for D2D transmission using the transmit power parameters; and transmitting a D2D signal through the non-serving carrier with the determined transmit power.

A method according to an embodiment of the present invention includes; A method for supporting signal transmission for D2D communication, the method comprising: generating system information including transmission power parameters for D2D transmission on a first carrier; and providing the system information with a second carrier It includes the process of transmitting to the terminal located in the second cell.

An apparatus according to an embodiment of the present invention includes; A terminal device for transmitting a signal for terminal-to-device (D2D) communication, wherein a terminal located in a serving cell providing a serving carrier receives system information including transmission power parameters for D2D transmission in a non-serving carrier a receiving unit, a control unit determining transmit power for D2D transmission using the transmit power parameters, and a transmitting unit transmitting a D2D signal through the non-serving carrier with the determined transmit power.

An apparatus according to an embodiment of the present invention includes; A base station apparatus supporting signal transmission for D2D communication, comprising: a control unit generating system information including transmission power parameters for D2D transmission in a first carrier; and providing the system information to a second carrier and a transmitter for transmitting to the terminal located in the second cell.

Other aspects, features and benefits as described above of certain preferred embodiments of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.
1 is a diagram illustrating a configuration of a system supporting D2D communication according to an embodiment of the present invention.
2 illustrates a system structure for providing D2D transmit power parameters according to an embodiment of the present invention.
3A illustrates a system structure for providing D2D transmission power parameters for a non-serving carrier from a serving cell according to an embodiment of the present invention.
3B illustrates another system structure for providing D2D transmission power parameters for a non-serving carrier from a serving cell according to an embodiment of the present invention.
3C illustrates a system structure for providing D2D transmission power parameters for a non-serving carrier from a neighboring cell according to an embodiment of the present invention.
4 is a flowchart illustrating a D2D transmission operation by a terminal on a non-serving carrier according to an embodiment of the present invention.
5 is a flowchart illustrating a D2D transmission operation by a terminal on a non-serving carrier according to another embodiment of the present invention.
6 is a message flow diagram illustrating an operation of providing system information of a neighboring cell for D2D transmission on a non-serving carrier according to an embodiment of the present invention.
7 is a flowchart illustrating an operation of a base station for supporting D2D transmission on a non-serving carrier according to an embodiment of the present invention.
8 is a block diagram illustrating the structure of a terminal according to an embodiment of the present invention.
9 is a block diagram showing the structure of a base station according to an embodiment of the present invention.
It should be noted that throughout the drawings, like reference numerals are used to denote the same or similar elements, features, and structures.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present invention pertains and are not directly related to the present invention will be omitted. This is to more clearly convey the gist of the present invention without obscuring the gist of the present invention by omitting unnecessary description.

For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings. In addition, the size of each component does not fully reflect the actual size. In each figure, the same or corresponding elements are assigned the same reference numerals.

Advantages and features of the present invention, and a method for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

At this time, it will be understood that each block of the flowchart diagrams and combinations of the flowchart diagrams may be performed by computer program instructions. These computer program instructions may be embodied in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions performed by the processor of the computer or other programmable data processing equipment are not described in the flowchart block(s). It creates a means to perform functions. These computer program instructions may also be stored in a computer-usable or computer-readable memory that may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable memory. It is also possible that the instructions stored in the flow chart block(s) produce an article of manufacture containing instruction means for performing the function described in the flowchart block(s). The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It is also possible that instructions for performing the processing equipment provide steps for performing the functions described in the flowchart block(s).

Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). It should also be noted that in some alternative implementations it is also possible for the functions recited in blocks to occur out of order. For example, two blocks shown one after another may be performed substantially simultaneously, or the blocks may sometimes be performed in the reverse order according to a corresponding function.

In this case, the term '~ unit' used in this embodiment means software or hardware components such as field-programmable gate array (FPGA) or ASIC (Application Specific Integrated Circuit), and '~ unit' refers to what role carry out the However, '-part' is not limited to software or hardware. '~' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Accordingly, as an example, '~' indicates components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, components and '~ units' may be implemented to play one or more CPUs in a device or secure multimedia card.

In describing the embodiments of the present disclosure in detail, the LTE-based cellular mobile communication system will be mainly targeted, but the main subject matter to be claimed in the present specification is also included in other communication systems and services having a similar technical background. Applicable within a range that does not significantly deviate from the disclosed scope, which will be possible at the discretion of a person having technical knowledge skilled in the art.

1 is a diagram illustrating a configuration of a system supporting D2D communication according to an embodiment of the present invention.

Referring to Figure 1, the cellular mobile communication system is its service area, that is, a base station (Base Station (BS) or Node B (NB) or enhanced NB (eNB)) 104 that covers the cell 102 as a basic unit do it with The base station 104 may manage radio resources used in the cell 102 . The terminal 106 in the cell 102 is configured to establish a D2D interface for D2D communication with the terminal 108 in the same cell 102 (or located in another cell). All or at least one of the terminals 106 and 108 may access the core network of the cellular mobile communication system through the base station 104 and receive support for D2D communication by the core network.

Terminals supporting D2D communication may receive control over authentication, security, and charging from the network in order to perform D2D communication, and may request a connection to the network when necessary for discovery. On the other hand, control signaling for D2D communication is transmitted and received between D2D terminals.

As an embodiment, a protocol stack for supporting D2D communication in the terminal may be composed of a D2D application layer, a D2D management layer, and a D2D transport layer. The D2D application layer refers to a D2D service application running on the operating system (OS) of the terminal, and the D2D management layer is responsible for converting the discovery information generated in the D2D application into a format suitable for the transport layer, and D2D transmission The layer refers to a physical (Physical: PHY) and MAC (Medium Access Control) layer. The D2D transport layer may be the same as the PHY/MAC layer of the LTE or WiFi wireless communication standard.

Inter-terminal discovery may have the following procedure. When a user executes a D2D application program, information for search is generated in the application layer and transmitted to the management layer. The management layer converts the discovery information received from the application layer into a management layer message. This management layer message is transmitted through the transport layer of the terminal. The terminal(s) receiving the management layer message performs a reception operation in the reverse order of the transmission procedure.

Terminal-to-device communication is a communication technology that directly transfers traffic between terminals without going through a network infrastructure such as a base station or an access point (AP). In the terminal-to-device communication, after the terminal-to-device discovery process is performed, communication between the terminals is performed based on the result (ie, with the discovered terminals), or the terminal-to-device communication may be performed without going through the terminal-to-device discovery process. Whether or not a discovery process between terminals is required prior to communication between terminals may be determined according to the D2D service and operation scenario.

D2D service scenarios may be broadly classified into a commercial service (commercial service or non public safety service) and a service related to public safety (PS) (public safety service). Representative examples of D2D service scenarios include advertisement, social network service (SNS), game, and public safety and public safety service.

1) Advertisement: A network operator that supports D2D can advertise pre-registered identities of stores, cafes, cinemas, restaurants, etc. to users of D2D terminals located in close proximity using device-to-device navigation or device-to-device communication. can In this case, the interests may be advertisements' promotions, event information, discount coupons, and the like. If the interests according to the advertised identity match the interests of the user, the user can obtain more information by visiting the store or accessing the terminal of the store using the existing cellular network or terminal-to-device communication. . As another example, an individual user searches for a taxi located in his/her vicinity through terminal-to-terminal search, and provides data on the terminal of the taxi searched through conventional cellular communication or terminal-to-terminal communication and his/her destination or fare information, etc. can receive

2) SNS (social network service): A user can transmit his/her application and his/her interest in the application to other users located nearby. In this case, the identity or interest used for inter-terminal search may be a friend list of an application or an application identifier. After the user searches between terminals, the user can share the contents such as photos and videos he owns with nearby users through terminal-to-device communication.

3) Game: A user searches for users and game applications through a terminal-to-device search process to enjoy a mobile game with users in close proximity, and communicates between terminals to transmit data necessary for the game. can do.

4) Public safety and disaster network service (public safety service): Police officers and firefighters may use D2D communication technology for the purpose of public safety. In other words, when cellular communication is not possible due to partial damage to the existing cellular network due to an emergency such as a fire or landslide or a natural disaster such as an earthquake, volcanic eruption, or tsunami, police officers and firefighters can use D2D communication technology to discover or Each emergency information can be shared between adjacent users.

In Release 12 of 3GPP LTE (hereinafter referred to as Rel-12 LTE), standardization of D2D communication for both discovery and communication between terminals is in progress. In Rel-12 LTE, inter-terminal search is for commercial use and is designed to operate only within the network coverage of the base station. That is, inter-terminal search is not supported in a situation in which the base station does not exist (or out of the coverage of the base station). Communication between terminals is for the purpose of public safety and disaster network services, not for commercial purposes, and some terminals exist within network coverage and some terminals are in network coverage and out of network coverage. They must all be supportable in partial network coverage that exists outside of network coverage. Therefore, in the public safety and disaster network service, communication between terminals must be performed without support for search between terminals.

In Rel-12 LTE, inter-terminal discovery and inter-terminal communication are both performed in an uplink subframe of LTE. That is, the transmitting terminal transmits a D2D discovery signal and data for D2D communication in the uplink subframe, and the receiving terminal receives them in the uplink subframe. In an existing LTE system (eg, a system of a previous release including Rel-11), the terminal receives data and control information from the base station through downlink, and transmits data and control information to the base station through uplink. Therefore, the operation of the D2D transmitter/receiver may be different from that of the existing LTE system. For example, a terminal that does not support the D2D function is equipped with an orthogonal frequency division multiple access (OFDMA)-based receiver to receive downlink data and control information from the base station, and transmits uplink data and control information to the base station. For transmission, a single carrier-frequency division multiple access (SC-FDMA) based transmitter is mounted. A terminal supporting both cellular mode and D2D mode is an OFDMA-based receiver for receiving downlink signals from a base station, an SC for transmitting data or control information through uplink to a base station, or for transmitting D2D data and control information - In addition to the FDMA-based transmitter, a separate SC-FDMA receiver is equipped to receive D2D data and control information through uplink.

Rel-12 LTE D2D defines the following two types of inter-terminal discovery according to the resource allocation method.

1) Type 1 discovery:

The base station broadcasts information on an uplink resource pool usable for D2D discovery to terminals supporting D2D communication (hereinafter referred to as D2D terminals) through a system information block (SIB). The SIB may be reached to all D2D terminals in the cell managed by the base station. The information is the size of a resource available for D2D, for example, the number of subframes that are time-domain resources and y resource blocks (RBs) that are frequency-domain resources (eg, a start point and an end point). , or a starting point and an offset (the number y)), and information on a period of resource allocation (eg, time-axis and frequency-axis resources are repeated every z second). Upon receiving the information, the D2D UEs transmit D2D discovery signals by distributedly selecting resources to be used.

There may be various methods for selecting a resource for D2D terminals to use for transmission of a D2D discovery signal from a resource pool allocated by the base station.

The simplest random resource selection method will be described as follows.

That is, the D2D transmitting terminal randomly selects a resource from the resource pool for type 1 discovery obtained through SIB, and transmits the D2D discovery signal through the randomly selected resource. D2D receiving terminals decode D2D discovery signals transmitted in all regions of the resource pool acquired through SIB. Type 1 discovery may be used by both terminals in a Radio Resource Control (RRC) idle state and an RRC connected state.

2) Type 2 discovery:

The base station broadcasts information on the resource pool that the D2D receiving terminals must monitor in order to receive the discovery signal through the SIB. A transmission resource (hereinafter referred to as a D2D transmission resource) of a discovery signal for D2D transmitting terminals is scheduled by the base station. That is, the base station instructs D2D transmitting terminals to transmit a discovery signal in a specific time-frequency resource. The scheduling of the base station may be performed through a semi-persistent method or a dynamic method, and the D2D transmitting terminal transmits a signal such as SR (Scheduling Request) or BSR (Buffer Status Report) to the base station. Request a D2D transmission resource. In order to use time 2 discovery, the D2D transmitting terminal must be in RRC connected mode. The D2D transmitting terminal in the RRC idle mode switches to the RRC connected mode through a random access procedure to request a D2D transmission resource.

Inter-terminal search should be supported not only between terminals located in the same cell, but also between terminals located in different cells. Therefore, the inter-terminal discovery is classified into intra-cell D2D discovery, which is a discovery between UEs located in the same cell, and inter-cell D2D discovery, which is a discovery between UEs located in different cells. can do. In addition, intra-cell D2D discovery and inter-cell D2D discovery can be subdivided into a synchronization operation and a resource allocation operation, respectively.

A synchronization operation for intra-cell D2D discovery will be described as follows.

The terminals receive a synchronization signal transmitted by the base station, for example, a primary synchronization signal (PSS) and/or a secondary synchronization signal (SSS) (hereinafter referred to as PSS/SSS), and perform downlink synchronization with the base station. In addition, the terminals may perform uplink synchronization with the base station to transmit uplink data and control information. Uplink synchronization is performed through a random access (RA) process, and in the uplink synchronization process, each terminal receives TA (Timing Advance) information from its serving base station. Upon receiving the TA information, the UE turns on the TA timer and maintains the TA value received from the base station until the TA timer expires. That is, the terminal that has obtained the TA information from the base station uses the TA value indicated by the TA information when transmitting control information and data through the uplink until the TA timer expires. When the TA timer expires, the UE re-performs the RA process to acquire TA information again.

The D2D discovery signal is transmitted based on the downlink reference time of the base station. The downlink reference time of the base station is applied to both type 1 discovery and type 2 discovery. That is, the D2D terminal transmits the D2D discovery signal based on the time point when the PSS/SSS is received from the serving base station.

A resource allocation operation for intra-cell D2D discovery will be described as follows.

The base station may transmit the following information through the SIB to support intra-cell D2D discovery.

- Discovery type: Transmits information on a discovery type (type 1 or type 2 or both) supported by the own cell.

- Transmission pool (transmission pool): Information on the transmission pool is applicable only to type 1 discovery. The D2D terminal supporting all type 1 discovery in the cell receives transmission pool information from the base station. The transmission pool information may include information on how the transmission pool is configured. For example, the number of subframes constituting the transmission pool, the number of resource blocks constituting the subframe, etc. may be included. The above information may be expressed in various forms. For example, the configuration of the D2D subframes may be displayed in the form of a bitmap such as '1011100...'. Here, '1' may mean a D2D subframe, and '0' may mean a cellular subframe. In addition, information on the number of resource blocks constituting the D2D subframe may be composed of a start point and an end point of the resource blocks on the frequency axis. A terminal supporting type 1 discovery selects a transmission resource by itself within a transmission pool received from the base station, and transmits a D2D discovery signal through the selected transmission resource.

- Reception pool: Information information about the reception pool is applicable to both type 1 discovery and type 2 discovery. All D2D terminals in the cell receive reception pool information from the base station. The reception pool information may include information on how the reception pool is configured, and the configuration method is the same as that of the transmission pool information. All D2D terminals in the cell monitor all resource blocks existing in the reception pool and decode the discovery signal. The transmit pool may be a subset of the receive pool. That is, within the reception pool composed of M subframes, there may be a transmission pool composed of N subframes, and M ≥ N.

A synchronization operation for inter-cell D2D discovery will be described as follows.

In a synchronization network, each base station synchronizes its own transmission and reception times using a Global Positioning System (GPS). Accordingly, the time synchronization of all base stations in the synchronization network coincides with each other. In contrast, in an asynchronous network, synchronization between base stations is not consistent. When synchronization between base stations does not match, the inter-cell interference problem may become more serious compared to a synchronization network. To solve this problem, in an asynchronous network, network synchronization is performed using an X2 interface between base stations or an S1 interface between a base station and a higher entity (eg, Mobility Management Element (MME)) existing in the core network. In this case, various network synchronization protocols may be used. However, even when synchronization between base stations is performed using a network synchronization protocol, synchronization accuracy of a subframe level between base stations cannot be provided. That is, with respect to the subframe boundary of cell A, the adjacent cell B may have an error that is late or early by 1/2 subframe (0.5 ms).

In type 1 discovery, the D2D terminal of each cell transmits a D2D discovery signal based on the downlink reference time of the serving base station. Therefore, in an asynchronous network in which synchronization between base stations existing in different cells does not match, a method for synchronizing synchronization between D2D terminals existing in different cells is needed. LTE Rel-12 D2D does not use an X2 interface between base stations to support cell-to-cell D2D operation. That is, the base station does not provide the timing information of the adjacent cell to the terminal of the serving cell using the X2 interface. Therefore, D2D Synchronization Signal (D2DSS) has been defined to perform synchronization between terminals existing between different cells without timing information of adjacent cells. That is, when the D2D UE of cell A transmits the D2DSS, the D2D UEs of the neighboring cell can find the subframe boundary of the resource region used for D2D discovery in cell A by receiving the D2DSS.

A resource allocation operation for inter-cell D2D discovery will be described as follows.

In order to support D2D operation between D2D terminals existing in different cells in an asynchronous network without exchanging timing information of adjacent cells through the X2 interface, OAM (Operation Administration Maintenance)-based resource allocation is being considered. That is, an upper entity (eg, MME) of the network acquires timing information (eg, System Frame Number (SFN)) of base stations it manages using the S1 interface, and each base station using the timing information allocates a resource (hereinafter referred to as a discovery resource) that can be used for D2D discovery. In particular, the discovery resource for one cell is allocated so as not to overlap with the discovery resources of other cells located in the vicinity on the time axis. For example, assuming that there are cells A, B, and C, the D2D resource pool of cell A is allocated for T1 time (for M1 subframes), and the D2D resource pool of cell B is allocated for T2 time (M2 subframes). frames), and the D2D resource pool of cell C allocates (during M3 subframes) for T3 time. Each D2D resource pool may be composed of consecutive D2D subframes or may be composed of non-contiguous D2D subframes. For example, when the D2D resource pool of cell A consists of consecutive D2D subframes, all subframes of the D2D resource pool allocated during the T1 time become D2D subframes. That is, all M1 subframes are used in D2D. On the other hand, when the D2D resource pool of cell A consists of non-consecutive D2D subframes, time division multiplexing (TDM) may be performed between subframes for cellular communication and subframes for D2D communication within T1 time.

The serving cell may transmit resource allocation information of the neighboring cell(s) to the UEs through the SIB. That is, the serving base station that manages the serving cell informs the UEs in the serving cell of not only information on the D2D resource pool to be used in the serving cell, but also information on the D2D resource pool used in the neighboring cell(s). The terminals perform D2D transmission and reception by using resource allocation information of the neighboring cell(s) received from the serving base station. In this case, D2D transmission may be performed in the D2D transmission pool of the serving cell (in case of type 1 discovery) or in a specific time-frequency resource in the D2D reception pool of the serving cell under the command of the base station (in case of type 2 discovery). Meanwhile, D2D reception is performed in both the D2D reception pool of the serving cell and the D2D reception pools of adjacent cells. For example, D2D transmitting terminals of cell A transmit a discovery signal using the D2D transmission pool within T1 time (in case of type 1 discovery), and D2D receiving terminals that do not perform D2D transmission in cell A within the D2D reception pool It monitors and decodes a discovery signal through all resource blocks (in case of type 1 discovery). In addition, D2D receiving terminals monitor and decode discovery signals through all resource blocks in D2D reception pools used in neighboring cell B and neighboring cell C (in case of type 1 discovery and type 2 discovery).

In Rel-12 LTE D2D, the D2D transmitting terminal is a serving cell (a cell to which a terminal in an RRC connected mode is connected is defined as a serving cell) or a camped cell (when the terminal is in RRC idle mode) , it is possible to transmit the discovery signal only in the frequency band of the cell in which the terminal is camping). A D2D transmitting terminal cannot transmit a D2D discovery signal in a frequency band used by a non-serving cell or a cell on which the UE is not camping, and is transmitted by another D2D transmitting terminal connected to or camping in an adjacent cell A D2D discovery signal may be received. For example, when the frequency band used by the serving cell or the camping cell is f1 and the frequency band used by the adjacent cell is f2, the D2D terminal selecting the cell using the frequency band of f1 as the serving cell or the camping cell is f1 D2D signal transmission and reception are possible in f2, and only D2D signal reception is possible in f2. Similarly, a D2D terminal that selects a cell using the frequency band of f2 as a serving cell or a camping cell can transmit and receive a D2D signal at f2 and only receive a D2D signal at f1.

On the other hand, in D2D communication operation unlike D2D discovery, when the frequency band f1 provided by the serving cell or camping cell is different from the frequency band f2 provided by the neighboring cell, the D2D transmitting terminal determines the frequency band f2 of the neighboring cell. ), D2D transmission is possible. However, the usage scenario is very limited. For example, there is a case where the frequency band f1 provided by the serving cell or the camping cell is limited for commercial use, and the frequency band f2 provided by the adjacent cell is used for public safety (PS) purposes. there is. In this case, the D2D transmitting terminal in the RRC idle mode moves to an adjacent cell using the frequency band f2 through a cell re-selection process. Meanwhile, the D2D transmitting terminal in the RRC connection mode follows the following procedure to perform inter-frequency handover in order to transmit D2D data and control information in a frequency band f2 provided by an adjacent cell.

1) The terminal receives the SIB including resource pool information for D2D communication from the serving base station.

- The SIB may be, for example, SIB 18 including Public Land Mobile Network (PLMN) identifiers (PLMN) of adjacent cells considered in the idle mode as well as the connected mode. The resource pool information includes configuration information of subframes that are time-axis information and configuration information of resource blocks that are frequency-axis information. The resource pool information corresponds to transmission pool information in Mode 2 communication, and corresponds to reception pool information in Mode 1 communication.

In terms of a method of resource allocation, mode 2 communication is similar to type 1 discovery, and mode 1 communication is similar to type 2 discovery. That is, to support mode 2 communication, the base station provides resource pool information to D2D terminals in the cell through SIB 18. The resource pool information is the size of resources available for D2D, for example, the number of time-domain subframes x, and frequency-axis resources, y resource blocks (RBs) information (eg, starting point). and end point, or start point and offset (number y)), and information on the period of resource allocation (eg, time-axis and frequency-axis resources are repeated every z second).

The resource pool information may independently include information on a resource pool for transmission of control information and a resource pool for transmission of data information. Among the D2D terminals receiving the information, the D2D transmitting terminal selects a resource to be used by the D2D terminal distributedly and transmits D2D data and control signals. Meanwhile, among the D2D terminals receiving the information, the D2D receiving terminal receives and decodes control information transmitted from the D2D transmitting terminal in the corresponding resource pool using the resource pool for the control information indicated in SIB 18. If the decoded control information includes the receiving terminal's own ID, data information indicated by the control information is received. If the control information does not include its own ID, the control information is discarded.

In mode 1 communication, the base station broadcasts information on the resource pool that D2D receiving terminals need to monitor in order to receive the discovery signal through SIB 18. A transmission resource (hereinafter referred to as a D2D transmission resource) of a discovery signal for D2D transmitting terminals is scheduled by the base station. That is, the base station instructs D2D transmitting terminals to transmit a discovery signal in a specific time-frequency resource. The scheduling of the base station may be performed through a semi-fixed method or a dynamic method, and the D2D transmitting terminal requests a D2D transmission resource by transmitting a signal such as SR or BSR to the base station. In order to use mode 1 communication, the D2D transmitting terminal must be in the RRC connected mode. The D2D transmitting terminal in the RRC idle mode switches to the RRC connected mode through a random access procedure to request a D2D transmission resource.) The D2D terminal transmits an Information Element (IE) called ProseUEInformation to the serving base station, and ProseUEInformation includes The following information is included.

- discRxInterest : Notifies the serving base station of whether the D2D terminal will receive a discovery signal.

- discTxResourceReq : The D2D terminal requests a resource for transmission of a discovery signal.

- commRxInterestedFreq : Notifies the base station of the frequency at which the D2D terminal wants to receive data/control information for communication between terminals.

- commTxResourceReq : The D2D terminal requests a resource for transmitting data/control information for communication between terminals from the base station. Specifically, commTxResourceReq may include carrierFreq indicating a frequency for transmission and proseDestinationInfoList indicating information of a terminal receiving data/control information.

3) The serving base station transmits a radio resource management (RRM) measurement command for inter-frequency handover to the D2D terminal.

- The RRM command includes a measurement time and a measurement period.

4) The D2D terminal performs measurement and transmits the measurement result to the serving base station.

5) The serving base station determines whether to perform inter-frequency handover based on the measurement result received from the D2D terminal.

- When the measurement result reported by the D2D terminal is greater than a specific threshold set by the base station, it is determined that the signal of the neighboring cell using the frequency band f2 can provide sufficient quality, and handover of the D2D terminal is determined. The D2D transmitting terminal that has performed the handover may transmit D2D data/control information in a frequency band of f2.

- In case the base station decides not to perform handover because the measurement result reported by the D2D terminal is not greater than a specific threshold set by the base station, or the base station determines handover because the measurement result is greater than the threshold value but the handover fails there is In this case, if the D2D terminal can obtain information on the mode 2 resource pool of the neighboring cell using the frequency band of f2, it may transmit data/control information from the mode 2 resource pool of the neighboring cell.

As an embodiment, information on the mode 2 resource pool includes information about the number of subframes that are time-domain resources x, and y resource blocks (RBs) that are frequency-domain resources (for example, a start point and an end point, or a start point and offset (number y)) and information on the period of resource allocation (eg, time-axis and frequency-axis resources are repeated every z second).

The information on the resource pool includes information on the resource pool required for transmitting control information (eg lengths on time and frequency axes, a period of resource allocation, etc.) and information on the resource pool required for transmitting data information (For example, lengths on a time axis and a frequency axis, a period of resource allocation, etc.) may be independently included. For example, the resource pool for transmitting control information is composed of the number of subframes x1, the number of resource blocks y1, and the resource allocation period z1, and the resource pool for transmitting data information is the number of subframes x2, the number of resource blocks The number y2 and the resource allocation period z2 may be configured. Information on the resource pools may be transmitted through the SIB.

As mentioned above, in D2D discovery or D2D communication of Rel-12 LTE, D2D signal transmission is possible only on a serving carrier, and a D2D transmitting terminal that wants to perform transmission on a non-serving carrier performs handover to a non-serving carrier. should be carried out The D2D transmitting terminal transmits the discovery signal so that the discovery signal does not affect the reception of a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) of the base station. control the power That is, the D2D transmitting terminal transmitting the D2D discovery signal on the serving carrier can obtain parameters related to D2D transmit power (hereinafter referred to as D2D transmit power parameters) through the SIB transmitted by the serving base station or the camping base station. As an example, the SIB may be SIB 19 including Inter-RAT (Radio Access Technology) frequency and priority information used in the cell, that is, the base station is D2D terminals existing in the cell. transmits the transmit power parameters to the user through SIB 19. The transmit power parameters that can be included in SIB 19 are the maximum transmit power value according to the Discovery Range (Power) Class and parameters for controlling the discovery transmit power. may include, each of which is as follows.

A. Maximum transmit power value according to search range (power) class

discTxPowerInfo included in SIB 19 represents ProseDiscTxPowerInfoList and discMaxTxPower . In this case, ProseDiscTxPowerInfoList indicates the number of discovery power classes supported in the cell (up to three), and discMaxTxPower means the maximum transmit power that can be used in each discovery power class. For example, when the number of discovery power classes supported in a cell = 3, discMaxTxPower may be defined as P _Long , P _Medium , and P _Short . In this case, P _Long is a transmission power capable of supporting a long range search, P _Medium is a transmission power capable of supporting a medium range search, and P _Short is a short range search. It means the transmit power that can support . P _Long , P _Medium , and P _Short may be defined differently for each D2D discovery resource pool allocated by the base station, and the same discovery power class is used for the same resource pool. For example, if there are 4 D2D discovery resource pools supported by one cell, discMaxTxPower usable in discovery resource pool 1 is P _Long , discMaxTxPower usable in discovery resource pool 2 is P _Medium , and can be used in discovery resource pool 3 The available discMaxTxPower is P _Short , and the available discMaxTxPower in the discovery resource pool 4 is P _Long . Therefore, D2D transmitting terminals transmitting a D2D discovery signal using discovery resource pool 1 use P _Long , and D2D transmitting terminals transmitting a D2D discovery signal using discovery resource pool 2 use P _Medium and discovery resource pool 3 Thus, D2D transmitting terminals transmitting a D2D discovery signal use P _Short , and D2D transmitting terminals transmitting a D2D discovery signal using discovery resource pool 4 use P _Long .

B. Parameters for search transmit power control

ProseDiscPoolList4 included in SIB 19 indicates transmission pool information for transmission of a discovery signal, and includes information on tx-parameters . For example, tx-parameters indicates a Prose-TxParameters Information Element , and the Prose-TxParameters Information Element includes parameters α and P ₀ for controlling transmit power.

The D2D transmitting terminal located in the serving cell or camping cell receives the search power class (hereinafter referred to as the search range class, P _{Range_Class} , P _{Range_Class} ∈{ P _Long , P _Medium , P _Short }) and transmit power received through SIB 19. Using the control parameters α and P ₀ , the D2D transmission power P _{Serving_carrier} in the serving carrier is determined as in Equation 1 below.

That is, the D2D transmitting terminal determines the transmission power in the serving carrier as a smaller value among P _{Power_Control} and P _{Range_Class} , where P _{Power_Control} is as shown in Equation 2 below.

Here, M represents the number of resource blocks used to transmit a D2D discovery signal, and M = 2 is used in Rel-12 LTE D2D discovery. PL means path loss between the base station and the terminal, and the terminal has a reference signal (RS) transmission power transmitted by the base station and RSRP (Reference Signal Received Power) measured by itself with respect to the reference signal to predict PL . That is, the D2D transmitting terminal estimates PL using the difference between referenceSignalPower, which is the reference signal transmission power provided through RRC signaling from the base station, and the received power measured by the D2D transmitting terminal for the reference signal. P _{UE_Class} is the maximum transmit power value determined according to the class of the UE, and may be 23 dBm or 31 dBm.

As described above, when D2D transmission is possible only on a serving carrier, which is a frequency provided by a serving cell or a camping cell, and only D2D reception is possible on a non-serving carrier, which is a frequency provided by an adjacent cell, the following problem may occur.

That is, the network operator may allow only discovery monitoring (ie, discovery reception) without allowing discovery transmission in a specific cell. In this case, the D2D transmitting terminal needs to perform D2D transmission on a non-serving carrier.

As another scenario, the search may be used for public safety and commercial purposes, where the serving carrier is a frequency band allocated for commercial use, and the non-serving carrier is a frequency band allocated for public safety use. A D2D transmitting terminal desiring to perform discovery transmission for safety purposes needs to perform D2D transmission on a non-serving carrier.

As another scenario, when the D2D transmitting terminal can transmit and receive simultaneously on different frequencies, the D2D transmitting terminal performs cellular uplink transmission on the serving carrier and simultaneously transmits the D2D discovery signal on the non-serving carrier. Needs to be.

Even in scenarios not described, the D2D transmitting terminal may need to perform D2D transmission on a non-serving carrier.

In the following embodiment, a method of obtaining transmission power parameters for transmitting a D2D discovery signal on a non-serving carrier and a method of determining a transmission power for transmitting a D2D discovery signal on a non-serving carrier are provided.

A method of obtaining transmit power parameters for transmitting a D2D discovery signal in a non-serving carrier includes a method in which a serving cell or a camping cell of a D2D transmitting terminal provides transmit power parameters in a non-serving carrier, and a non-serving carrier. The providing neighbor cell may be classified in such a way that it directly provides the transmit power parameters. In addition, the method of determining the D2D transmission power may be classified into a method based on RSRP of a serving base station providing a serving carrier and a method based on RSRP of a neighboring base station providing a non-serving carrier.

Hereinafter, embodiments of obtaining D2D transmission power parameters for transmitting a D2D discovery signal on a non-serving carrier will be described.

First, embodiments in which a serving cell or a camping cell provides transmit power parameters in a non-serving carrier are described.

As an embodiment, SIB 19 of a serving cell or a camping cell includes transmit power parameters used in a non-serving carrier.

An example in which cell A is a serving cell providing a serving carrier and cell B is a neighboring cell providing a non-serving carrier will be described. The base station of cell A transmits at least one of P _0,A , α _A , and P _{Range_Class,A} , which are transmission power parameters for D2D discovery, through SIB 19 to all D2D terminals of the cell(s) it controls. . Similarly, the base station of cell B transmits at least one of P _0,B , α _B , and P _{Range_Class,B} through SIB 19 to all D2D terminals of the cell(s) it controls. In addition, the base station of cell A, in order to support the D2D terminal connected to cell A to perform D2D transmission on the non-serving carrier of cell B, P _0,B which is the transmission power parameters of cell B through SIB 19 , α _B , and P Transmit at least one of _{Range_Class,B} . To this end, the base station of cell A obtains transmit power parameters from the base station of cell B through the X2 interface.

In another embodiment, the base station of cell A may obtain the transmission power parameters of cell B from the MME through the S1 interface, which is an interface between each base station and a network entity such as the MME. In another embodiment, the base station of the cell A may obtain the transmit power parameters of the cell B from the local entity through a newly defined interface between the random local entity and each base station. In this case, the local entity may be an entity defined to support D2D transmission in a non-serving carrier, not a base station or an MME.

As another embodiment, the transmit power parameter of the serving carrier instead of the transmit power parameters of the non-serving carrier is applied to the D2D discovery transmission of the non-serving carrier.

A D2D transmitting terminal connected to or camping in cell A transmits a D2D discovery signal through a non-serving carrier of cell B using transmit power parameters provided through SIB 19 of cell A. That is, the D2D transmitting terminal does not use at least one of P _0,B , α _B , and P _{Range_Class,B} when transmitting the D2D discovery signal on the non-serving carrier of cell B, but P _{0 obtained from cell A,} Use at least one of _A , α _A , and P _{Range_Class,A} . At this time, there may be various modifications. As mentioned above, all three parameters used in the serving cell or camping cell of the D2D transmitting terminal may be used when transmitting the D2D discovery signal on the non-serving carrier, and some of the three parameters may be used. For example, the D2D transmitting terminal may determine the D2D transmission power in the non-serving carrier by using P _0,A , α _A and P _{Range_Class,B} . In this case, the base station of cell A obtains information about P _{Range_Class,B} of cell B through X2, S1 or other interfaces, and sets P _{Range_Class,B} together with P _0,A and α _A in SIB 19 of cell A transmit as transmit power parameters for the non-serving carrier.

Next, embodiments in which an adjacent cell providing a non-serving carrier provides transmit power parameters are described.

The D2D transmitting terminal located in the serving cell or the camping cell obtains transmission power parameters for D2D discovery transmission used in the neighboring cell by receiving and decoding SIB 19 transmitted by the base station of the neighboring cell.

As an embodiment, the D2D transmitting terminal located in the serving cell or the camping cell receives the SIB 19 of the neighboring cell only when it is switched from the RRC idle mode or the RRC connected mode to the DRX (Discontinuous Reception) mode. Here, the DRX mode refers to a state in which the receiving circuit of the D2D transmitting terminal is tuned to the frequency of the adjacent cell instead of the frequency of the serving cell or the camping cell.

As another embodiment, the D2D transmitting terminal in the RRC connected mode located in the serving cell or the camping cell may request the serving base station for D2D discovery transmission on a non-serving carrier. The serving base station instructs D2D transmitting terminals to receive SIB 19 of an adjacent cell in response to the request of the D2D transmitting terminal or at the discretion of the base station without the request of the D2D transmitting terminal, and the D2D transmitting terminal responds to the command of the base station In response, SIB 19 of the neighboring cell is received.

The D2D transmitting terminal, which has obtained transmit power parameters for D2D discovery transmission through the aforementioned methods, determines the transmit power of the D2D discovery signal using the calculated PL value and the obtained transmit power parameters. In this case, the PL calculation uses the reception power of the reference signal transmitted from the base station of the serving cell or the camping cell (ie, RSRP of the serving carrier), or the reception of the reference signal transmitted from the base station of the adjacent cell providing the non-serving carrier. This can be done using power (ie RSRP of non-serving carrier).

PL calculation using RSRP of the serving carrier will be described below.

The D2D transmitting terminal uses the PL calculated from RSRP measured from the serving cell (or camping cell) providing the serving carrier and the D2D transmit power parameters obtained through the SIB for the transmission of the D2D discovery signal on the non-serving carrier. D2D transmission power may be determined. At this time, the D2D transmitting terminal acquires the D2D transmit power parameters of the non-serving carrier through SIB 19 of the serving base station (or the base station of the camping cell) that provides the serving carrier ( P _0,B , α _B , P _{Range_Class,B} at least one of), or D2D transmission power parameters (at least one of P _0,A , α _A , P _{Range_Class,A} ) of the serving carrier used in the serving base station (or the base station of the camping cell) can be used. .

When the D2D transmit power parameters of the non-serving carrier are provided through SIB 19 of the serving base station (or the base station of the camping cell), the transmit power P _{Non-Serving_carrier} for transmitting the D2D discovery signal on the non-serving carrier is < It is calculated by Equation 3> and <Equation 4>.

Here, PL _A means a path loss calculated using RSRP between the base station of cell A providing the serving carrier and the D2D transmitting terminal and the referenceSignalPower provided by the base station of cell A through RRC signaling.

When the D2D transmission power parameters of the serving base station are used, the transmission power P _{Non-Serving_carrier} for transmitting the D2D discovery signal on the non-serving carrier is calculated by Equation 5 and Equation 6 below.

Here, the search range _class is P _{Range_Class} , _A, which is a parameter obtained from the base station of cell A as shown in Equation 5, or P _{Range_Class ,B,} which is a parameter of cell B obtained through SIB 19 of cell A can be

Next, PL calculation using RSRP of a non-serving carrier will be described.

The D2D transmitting terminal may determine the D2D transmit power for transmission of the D2D discovery signal on the non-serving carrier by using the PL calculated from RSRP measured from the neighboring cell providing the non-serving carrier and the D2D transmit power parameters. At this time, the D2D transmitting terminal acquires the D2D transmit power parameters of the non-serving carrier through SIB 19 of the serving base station (or the base station of the camping cell) that provides the serving carrier ( P _0,B , α _B , P _{Range_Class,B} ), or D2D transmission power parameters ( P _0,A , α _A , P _{Range_Class,A} ) of the serving carrier used in the serving base station (or the base station of the camping cell) may be used.

When the D2D transmit power parameters of the non-serving carrier are provided through SIB 19 of the serving base station (or the base station of the camping cell), the transmit power P _{Non-Serving_carrier} for transmitting the D2D discovery signal on the non-serving carrier is < It is calculated by Equation 7> and <Equation 8>.

Here, PL _B is RSRP between the base station of cell B and the D2D transmitting terminal providing the non-serving carrier, and the base station of cell A obtained through X2, S1 or other interface and provided to the D2D transmitting terminal through RRC signaling. It means the path loss calculated using the referenceSignalPower of the base station of cell B.

When the D2D transmission power parameters of the serving base station are used, the transmission power P _{Non -} Serving_carrier for transmitting the D2D discovery signal on the non _{- serving carrier} is calculated by the following <Equation 9> and <Equation 10> .

Here, the search range _class is P _{Range _ Class ,A} which is a parameter obtained from the base station of cell A as in <Equation 9>, or P _{Range_Class} , which is a _parameter of cell B obtained through SIB 19 of cell A _, can be _B.

In the above, the case where the transmission power parameters are applied for D2D discovery has been described, but it goes without saying that the same transmission power parameters or other transmission power parameters obtained through a similar procedure may be used for D2D communication, that is, transmission of a data signal. .

In addition to this, various modifications are possible. For example, instead of P _{Range_Class,B} used in <Equation 3> or <Equation 7>, P _{Range_Class,A} used in cell A may be used. As another example, instead of P _{Range_Class,A} used in <Equation 5> or <Equation 9>, P _{Range_Class,B} used in cell B may be used.

2 illustrates a system structure for providing D2D transmit power parameters according to an embodiment of the present invention.

Referring to FIG. 2 , cell A 202 is served by base station A (eNB-A) 204 , and terminal A (UE-A) 206 is connected to base station A 204 (RRC connection). mode) or simply camping in cell A 202. (RRC idle mode) Cell B 212 is served by a base station B (eNB-B) 214 , and terminal B 216 is served by a base station B 214 . ) (RRC connected mode) or simply camped in cell B 212 (RRC idle mode).

Each of the base stations 204 and 214 transmits transmit power parameters for D2D transmission to the D2D terminals 206 and 216 connected to their cells 202 and 212 through the SIBs 208 and 218 , for example, SIB 19 . In an embodiment, the transmit power parameters include at least one of P ₀ , α, and P _{Range_Class} . In addition, each of the base stations 204 and 214 transmits referenceSignalPower , which is a parameter indicating the transmission power of a reference signal, through the RRC signaling 210 and 220 , so that it can be used for calculation of a path loss required to determine the transmission power.

Base station A 204 transmits transmit power parameters to terminal A 206 in cell A 202 via SIB 19-A 208 (meaning SIB 19 transmitted from base station A 204), and RRC ReferenceSignalPower-A (referenceSignalPower transmitted from base station A 204), which is the reference signal transmission power of base station A 204 through signaling 210 (SIB 2-A: means SIB 2 transmitted from base station A 204) means) is transmitted. Similarly, base station B 214 transmits transmit power parameters to terminal B 216 in cell B 212 via SIB 19-B 218 (meaning SIB 19 transmitted from base station B 214) and , referenceSignalPower-B (base station B 214), which is the reference signal transmission power of the base station B 214 through RRC signaling 220 (or SIB 2-B: means SIB 2 transmitted from the base station B 214) It means the referenceSignalPower to be transmitted).

Terminal A 206 is the transmission power parameters obtained through SIB 19-A 208, referenceSignalPower-A obtained through RRC signaling 210 (or SIB 2-A), and the terminal A 206 is measured Using RSRP for one base station A 204 , a transmission power for transmitting a D2D discovery signal through a serving carrier of cell A 202 is calculated. Similarly, terminal B 216 obtains transmit power parameters through SIB 19-B 218 and referenceSignalPower-B obtained through RRC signaling 220 (or SIB 2-B), and in terminal B 216 . Using the measured RSRP with the base station B 214 , the transmission power used to transmit the D2D discovery signal through the serving carrier of the cell B 212 is calculated.

The terminals 206 and 216 may transmit D2D discovery signals with the calculated transmit power through a resource given for D2D discovery.

3A illustrates a system structure for providing D2D transmission power parameters for a non-serving carrier from a serving cell according to an embodiment of the present invention.

Referring to FIG. 3A , cell A 302 is served by base station A (eNB-A) 304 , and terminal A (UE-A) 306 is connected to base station A 304 (RRC connection). mode) or simply camping in cell A 302. (RRC idle mode) Cell B 312 is serviced by a base station B (eNB-B) 314 , and terminal B 316 is served by a base station B 314 . ) (RRC connected mode) or simply camped in cell B 312 (RRC idle mode).

Terminal A 306 connected to base station A 304 of cell A 302 or camping in cell A 302 is D2D on a non-serving carrier provided by base station B 314 of cell B 312 . A case in which transmission is performed will be described. To this end, the base station A 304 obtains the D2D transmit power parameters 318 (ie, P _0,B , α _B , P _{Range_Class,B} ) for the cell B 312 through the X2 interface 320 , and the The D2D transmit power parameters 318 are sent to UE A 306 in cell A 302 via SIB-A 308 . When the PL calculation is made based on the RSRP of the base station B 314 in the terminal A 306 , the base station A 304 is referenceSignalPower-B , which is the reference signal transmission power of the base station B 314 used in the cell B 312 . is obtained through the X2 interface 320 , and the obtained referenceSignalPower-B is provided to the terminal A 302 through the RRC signaling 310 .

3B illustrates another system structure for providing D2D transmission power parameters for a non-serving carrier from a serving cell according to an embodiment of the present invention.

Referring to FIG. 3B , cell A 302 is served by base station A (eNB-A) 304 , and terminal A (UE-A) 306 is connected to base station A 304 (RRC connection). mode) or simply camping in cell A 302. (RRC idle mode) Cell B 312 is serviced by a base station B (eNB-B) 314 , and terminal B 316 is served by a base station B 314 . ) (RRC connected mode) or simply camped in cell B 312 (RRC idle mode).

Terminal A 306 connected to base station A 304 of cell A 302 or camping in cell A 302 is D2D on a non-serving carrier provided by base station B 314 of cell B 312 . A case in which transmission is performed will be described. To this end, the base station A 304 transmits the D2D transmit power parameters (ie, at least one of P _0,B , α _B , and P _{Range_Class,B} ) for the cell B 312 through the S1 interface or a separate interface 320a. and transmits the D2D transmission power parameters to the UE A 306 in the cell A 302 via the SIB-A 308a. Similarly, the base station B 314 obtains the D2D transmit power parameters (ie, at least one of P _0,B , α _B , P _{Range_Class,B} ) for the cell A 302 through the S1 interface or a separate interface 320a. and transmit the D2D transmission power parameters to the UE B 316 in the cell B 312 through the SIB-A 308b.

When the PL calculation is made based on the RSRP of the base station B 314 in the terminal A 306 , the base station A 304 is referenceSignalPower-B , which is the reference signal transmission power of the base station B 314 used in the cell B 312 . may be obtained through the S1 interface or a separate interface 320a, and the obtained referenceSignalPower-B may be provided to the terminal A 302 through RRC signaling.

3C illustrates a system structure for providing D2D transmission power parameters for a non-serving carrier from a neighboring cell according to an embodiment of the present invention.

Referring to FIG. 3C , cell A 302 is served by base station A (eNB-A) 304 , and terminal A (UE-A) 322 is connected to base station A 304 (RRC connection). mode) or simply camping in cell A 302 . (RRC idle mode) Cell B 312 is served by a base station B (eNB-B) 314 and is adjacent to cell A 302 . The base station B 314 is similar to FIG. 3A , the SIB-B 324 containing transmission power parameters for D2D terminals in the cell B 312 and the RRC signaling 326 containing information on the reference signal transmission power. is sending

Terminal A 306 in cell A 302 receives SIB-B 324 transmitted by base station B 314 in order to transmit a D2D discovery signal on a non-serving carrier used in cell B 312, Transmission power parameters (ie, P _0,B , α _B , P _{Range_Class,B} ) for D2D discovery transmission are obtained from the SIB-B 324 . In addition, the terminal A 306 obtains referenceSignalPower-B , which is the reference signal transmission power used in the cell B 312, from the base station B 314 through the RRC signaling 326 (or SIB 2), and the obtained referenceSignalPower PL is calculated using RSRP measured for -B and base station B 314 . The terminal A 306 determines the transmission power to be used for transmitting the D2D discovery signal by using the calculated PL and the transmission power parameters obtained from the SIB-B 324 .

4 is a flowchart illustrating a D2D transmission operation by a terminal on a non-serving carrier according to an embodiment of the present invention.

4, in step 410, the terminal obtains transmission power parameters for D2D transmission on a non-serving carrier by receiving system information transmitted from a serving base station, or by directly receiving system information transmitted from a neighboring base station Obtain transmit power parameters for D2D transmission on a non-serving carrier. In step 420, the UE calculates a PL using the transmit power parameters, and in step 430 determines a transmit power for D2D transmission based on the PL . Calculation of PL may be performed based on RSRP with a serving base station or RSRP with a neighboring base station. In step 440, the UE transmits a D2D discovery signal with the determined transmission power through a predetermined or scheduled D2D transmission resource by the base station. As a modified embodiment, the determined transmission power or the transmission power determined according to a similar procedure may be used for transmission of the D2D data signal.

5 is a flowchart illustrating a D2D transmission operation by a terminal on a non-serving carrier according to another embodiment of the present invention.

Referring to FIG. 5 , in step 505, the UE checks a condition for determining whether to use RSRP with a neighboring base station for calculating PL, and if the condition is satisfied, proceeds to step 510. If not, proceeds to step 530 proceed to A detailed description of the above conditions will be given later.

In case of proceeding to step 510, the UE calculates PL based on RSRP measured for the reference signal transmission power of the neighboring base station providing the non-serving carrier and the reference signal from the neighboring base station. In step 515, the terminal acquires the transmission power parameters for the non-serving carrier through system information transmitted from the base station or the adjacent base station of the serving cell. Here, although process 510 is illustrated as being performed before process 515, process 515 may be performed first, or process 510 and process 515 may be performed simultaneously. In step 520, the UE determines the transmit power for the non-serving carrier based on the calculated PL and transmit power parameters, and in step 520 transmits a D2D discovery signal with the transmit power through the non-serving carrier.

In case of proceeding to step 530, the terminal calculates PL based on the RSRP measured for the reference signal transmission power of the serving base station providing the serving carrier and the reference signal from the serving base station. In step 535, the terminal acquires transmission power parameters for the serving carrier through system information transmitted from the base station of the serving cell. Here, although process 530 is illustrated as being performed before process 535, process 535 may be performed first, or process 530 and process 535 may be performed simultaneously. In step 520, the UE determines the transmit power for the non-serving carrier based on the calculated PL and transmit power parameters, and in step 520 transmits a D2D discovery signal with the transmit power through the non-serving carrier.

The conditions of step 505 will be described as follows.

As an embodiment, an implicit command of the serving base station may be used. For example, the terminal determines "whether the serving base station provides transmit power parameters for D2D transmission on a non-serving carrier", and if so, the terminal implicitly indicates that the serving base station uses RSRP with a neighboring base station can be judged to have been That is, when the terminal acquires the transmission power parameters in the non-serving carrier from the serving base station, it determines to use the RSRP with the neighboring base station for calculating the PL. On the other hand, if the serving base station does not provide the transmit power parameters in the non-serving carrier, the UE determines to use the RSRP of the serving base station for calculating the PL, or does not perform transmit power control. When transmit power control is not performed, the terminal uses the maximum transmit power. This implicit command method can be applied to both the D2D terminal in the RRC connected mode and the D2D terminal in the RRC idle mode.

As another embodiment, the serving base station may explicitly instruct the terminal to operate the terminal for RSRP measurement on a non-serving carrier. For this, as an example, dedicated signaling may be used. Specifically, the terminal determines "whether the serving base station has commanded RSRP measurement on a non-serving carrier", and if so, determines to use RSRP with a neighboring base station for PL calculation. The serving base station instructs RSRP measurement on the non-serving carrier, and also provides transmit power parameters on the non-serving carrier to the terminal. On the other hand, if the serving base station does not command RSRP measurement on the non-serving carrier, or commands RSRP measurement on the serving carrier, the terminal uses RSRP with the serving base station that provides the serving carrier for the calculation of PL. decide that As an example, the serving base station may not provide transmit power parameters on the non-serving carrier when ordering RSRP measurement on the serving carrier. Then, the UE determines the transmission power for D2D transmission by using the transmission power parameters used in the serving carrier and RSRP in the serving carrier.

6 is a message flow diagram illustrating an operation of providing system information of a neighboring cell for D2D transmission on a non-serving carrier according to an embodiment of the present invention. Here, the serving carrier used by the serving cell is f1, the non-serving carrier used by the adjacent cell is f2, and the terminal is in an RRC connection state connecting to the base station of the serving cell.

Referring to FIG. 6 , in step 605 , the serving base station of the serving cell providing the serving carrier f1 transmits transmission power parameters for D2D transmission on the serving carrier through SIB 19 . For D2D transmission on the non-serving carrier f2, in step 610, the UE requests the serving base station for system information of a neighboring cell providing the non-serving carrier. As an embodiment, the request of step 610 may include discTxInterest indicating that the terminal wants to transmit a D2D discovery signal on a non-serving carrier, and an interested frequency indicating a carrier frequency of a non-serving carrier that the terminal wants to transmit. When the terminal is in the RRC connection state, the information elements for the request are transmitted to the serving base station through ProseUEInformation . When the UE is in the RRC_Idle state, the UE may transmit ProseUEInformation after switching to the RRC_Connected state.

In step 615, the serving base station transmits an RRM measurement command to the terminal. The RRM measurement command may include at least one of a measurement period for RRM measurement, a measurement frequency f2, and an ID of a measurement cell.

In step 620, the UE performs synchronization with the neighboring cell using the PSS/SSS of the neighboring cell using the non-serving carrier f2, and receives a Master Information Block (MIB) from the base station of the neighboring cell. The MIB includes information on the system bandwidth and the system frame number used in the adjacent cell. On the other hand, when the frequency f2 indicated for measurement by the serving base station is not an adjacent cell but is used in an out-of-coverage environment in which a base station does not exist, the terminal communicates with the terminals outside the coverage D2D communication Synchronization is performed using PSSS (Primary Sidelink Synchronization Signal)/SSSS (Secondary Sidelink Synchronization Signal), a synchronization signal transmitted for , and MIB-SL (MIB-Side Link) is received from the corresponding synchronized terminal. The MIB-SL includes information necessary to receive a reference signal transmitted from the synchronized terminal. As a specific example, MIB-SL is a 14-bit D2D frame number, a 3-bit identifier indicating the TDD (Time Division Duplex) UL-DL configuration (set to '000' in the case of FDD), a 1-bit in-coverage indicator (In-coverage indicator) (indicating whether the terminal is located within coverage or out of coverage), and 3 bits of D2D system bandwidth information.

In step 625, the UE measures RSRP with respect to a cell-specific reference signal (CRS) transmitted from a base station of a neighboring cell, or a DMRS (De-Modulation Reference Signal) transmitted by an out-of-coverage UE through a Physical Sidelink Broadcast CHannel (PSBCH). RSRP is measured for , and a measurement report including the measurement result is reported to the serving base station in step 630.

In step 635, the serving base station determines whether the terminal will receive the SIB of a neighboring cell providing a non-serving carrier based on the measurement report from the terminal, and in step 640 transmits a command according to the determination result to the terminal. When the command permits receiving the SIB of the neighboring cell providing the non-serving carrier, the terminal receives the SIB from the base station of the neighboring cell in step 645, and in step 645 obtains transmit power parameters from the SIB, The referenceSignalPower, which is the reference signal transmission power of the neighboring cell, is acquired through RRC signaling. Thereafter, the terminal may determine the transmission power for D2D transmission on the non-serving carrier based on the obtained information.

7 is a flowchart illustrating an operation of a base station for supporting D2D transmission on a non-serving carrier according to an embodiment of the present invention.

Referring to FIG. 7, in step 700, the base station may instruct the UE in the cell it manages to measure RSRP at a non-serving frequency. As another embodiment, the base station provides transmit power parameters for D2D transmission on the non-serving carrier through the SIB, and the terminal determines to perform RSRP measurement at the non-serving frequency in response to the reception of the transmit power parameters. can The base station may command RSRP measurement in the non-serving frequency according to the request of the terminal or the determination of the base station.

In step 705, the base station receives a measurement report including the RRM measurement result from the UE in the cell, and in step 710, determines whether the RSRP indicated by the RRM measurement result is greater than a predetermined threshold value (TH). If the RSRP is greater than the threshold, the process proceeds to step 730; otherwise, the process proceeds to step 715.

In step 730, the base station instructs the terminal to receive SIB 19 of a neighboring cell providing a non-serving carrier. The command may be implicitly or explicitly delivered to the terminal. When the implicit command is used, the serving base station does not provide information about transmit power parameters to be used in the non-serving carrier in the serving cell. When an explicit command is used, the serving base station transmits dedicated signaling instructing the terminal in the serving cell to receive SIB 19 of the adjacent cell, or the serving base station provides transmit power parameters in the non-serving carrier through the SIB. Information not to be transmitted can be transmitted.

In step 715, the base station instructs the terminal not to receive SIB 19 of a neighboring cell providing a non-serving carrier. This is because it is determined that the UE cannot normally receive the signal of the neighboring cell because the RSRP measured by the UE is small. As another embodiment, the base station may implicitly instruct not to receive SIB 19 of a neighboring cell by not transmitting a reception command for a non-serving carrier to the terminal. In step 720, the base station transmits the transmit power parameters usable in the non-serving carrier (and additionally, if necessary, the reference signal transmit power of the neighboring cell) from the base station, MME or other local entity of the neighboring cell through X2, S1 or other interfaces. In step 725, the acquired transmission power parameters are transmitted to the terminal in the serving cell through SIB 19, and, if necessary, additionally information on the reference signal transmission power of the neighboring cell is transmitted to the terminal in the serving cell through RRC signaling.

8 is a block diagram illustrating the structure of a terminal according to an embodiment of the present invention.

Referring to FIG. 8 , the terminal includes a control unit 810 , a D2D communication unit 820 , a wireless communication unit 830 , and a memory 840 . The D2D communication unit 820 generates and transmits a discovery signal and/or a control/data signal for D2D communication, or receives and detects a discovery signal and/or a control/data signal from another terminal. The wireless communication unit 830 is responsible for transmitting and receiving signals with the base station. The controller 810 controls the D2D communication unit 820 and the wireless communication unit 830 according to at least one of the above-described embodiments of the present invention. The memory 840 may store program codes and parameters necessary for the operation of the controller 810 .

9 is a block diagram showing the structure of a base station according to an embodiment of the present invention.

Referring to FIG. 9 , the base station includes a control unit 910 , an X2 communication unit 920 , a wireless communication unit 930 , and a memory 940 . The X2 communication unit 920 is in charge of communication between base stations, transmits information necessary to support D2D communication to another base station, receives information necessary to support D2D communication from another base station, and transmits it to the control unit 910 . The wireless communication unit 930 is responsible for transmitting and receiving signals with terminals. The controller 910 controls the X2 communication unit 920 and the wireless communication unit 930 according to at least one of the above-described embodiments of the present invention. The memory 940 may store program codes and parameters necessary for the operation of the controller 910 .

As described above, the embodiments of the present invention support the transmission of the D2D signal on the non-serving carrier, so that the UE can normally perform D2D communication even when it cannot transmit the D2D signal on the serving carrier.

The various embodiments of the present invention described above may be implemented as computer readable code in a computer readable recording medium in a specific point of view. A computer readable recording medium is any data storage device capable of storing data that can be read by a computer system. Examples of computer-readable recording media include read only memory (ROM: ROM), random access memory (RAM: 'RAM), and compact disk-read only memory (compact disk-read only memory). memory: CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves (such as data transmission over the Internet); may include The computer readable recording medium may also be distributed over network coupled computer systems, so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for achieving various embodiments of the present invention may be easily interpreted by programmers skilled in the field to which the present invention is applied.

In addition, it will be appreciated that the apparatus and method according to various embodiments of the present invention can be realized in the form of hardware, software, or a combination of hardware and software. Such software may include, for example, a volatile or non-volatile storage device, such as a ROM, or a memory, such as, for example, RAM, a memory chip, device or integrated circuit, whether erasable or rewritable, or For example, the storage medium may be stored in an optically or magnetically recordable storage medium such as a compact disk (CD), a DVD, a magnetic disk, or a magnetic tape, and a machine (eg, computer) readable storage medium. The method according to various embodiments of the present invention may be implemented by a computer or portable terminal including a control unit and a memory, and the memory is to store a program or programs including instructions for implementing the embodiments of the present invention. It will be appreciated that this is an example of a suitable machine-readable storage medium.

Accordingly, the present invention includes a program including code for implementing the apparatus or method described in the claims of the present specification, and a machine (computer, etc.) readable storage medium storing the program. Also, such a program may be transmitted electronically over any medium, such as a communication signal transmitted over a wired or wireless connection, and the present invention suitably includes the equivalent thereof.

Also, the device according to various embodiments of the present disclosure may receive and store a program from a program providing device connected by wire or wirelessly. The program providing device includes a program including instructions for causing the program processing device to perform a preset content protection method, a memory for storing information necessary for the content protection method, and a method for performing wired or wireless communication with the graphic processing device. It may include a communication unit and a control unit that automatically transmits a corresponding program to a transceiver or a request from a graphic processing device.

The embodiments of the present invention disclosed in the present specification and drawings are merely provided for specific examples to easily explain the technical contents of the present invention and to help the understanding of the present invention, and are not intended to limit the scope of the present invention. In addition, the embodiments according to the present invention described above are merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent ranges of embodiments are possible therefrom. Accordingly, the true technical protection scope of the present invention should be defined by the following claims.

Claims (20)

A method for transmitting a D2D discovery signal by a user equipment (UE) in a communication system supporting a device to device (D2D) scheme, the method comprising:
receiving system information from a serving cell;
determining transmission power for D2D discovery signal transmission in a frequency band of another cell based on the received system information of the serving cell; and
transmitting a D2D discovery signal in the frequency band of the other cell with the determined transmission power;
The transmission power is determined based on a path loss of the other cell, and the information on the frequency band of the other cell is received in the frequency band of the serving cell. How the UE transmits a D2D discovery signal in . delete delete delete delete The method of claim 1,
The method for the UE to transmit a D2D discovery signal in a communication system supporting the D2D scheme, wherein the system information includes D2D discovery resource information for another cell. 7. The method of claim 6,
The method for a UE to transmit a D2D discovery signal in a communication system supporting the D2D scheme, characterized in that the D2D discovery resource information for the other cell includes D2D transmission power parameters related to transmitting the D2D discovery signal. 8. The method of claim 7,
The method for the UE to transmit a D2D discovery signal in a communication system supporting the D2D scheme, wherein the D2D transmission power parameters are related to D2D discovery resource configuration. A method for a serving base station to support D2D discovery signal transmission of a user equipment (UE) in a communication system supporting a device to device (D2D) scheme, the method comprising:
detecting D2D discovery resource information for another cell; and
Transmitting D2D discovery resource information for the other cell in the serving cell,
The D2D discovery resource information of the other cell is used to transmit a D2D discovery signal in the frequency band of the other cell, and the D2D discovery resource information for the other cell is a D2D transmission power parameter related to transmission of the D2D discovery signal in the UE. A method for a serving base station to support D2D discovery signal transmission of a UE in a communication system supporting the D2D scheme, comprising: delete 10. The method of claim 9,
wherein the D2D transmission power parameter is related to a corresponding D2D discovery resource configuration, wherein a serving base station supports D2D discovery signal transmission of the UE in a communication system supporting the D2D scheme. In a user equipment (UE) in a communication system supporting a device to device (D2D) scheme,
Receive system information from a serving cell, determine a transmission power for D2D discovery signal transmission in a frequency band of another cell based on the received system information of the serving cell, and use the determined transmission power to determine a frequency band of the other cell Including a processor configured to transmit a D2D discovery signal,
The transmission power is determined based on a path loss of the other cell, and the information on the frequency band of the other cell is received in the frequency band of the serving cell. from UE. delete delete delete 13. The method of claim 12,
The system information UE in a communication system supporting the D2D scheme, characterized in that it includes D2D discovery resource information for another cell. 17. The method of claim 16,
The UE in a communication system supporting the D2D scheme, characterized in that the D2D discovery resource information for the other cell includes D2D transmission power parameters related to transmitting the D2D discovery signal. 18. The method of claim 17,
The UE in a communication system supporting the D2D scheme, wherein the D2D transmission power parameters are related to D2D discovery resource configuration. In a serving base station in a communication system supporting a device to device (D2D) scheme,
a processor configured to detect D2D discovery resource information for another cell, and to transmit D2D discovery resource information for the other cell in a serving cell;
The D2D discovery resource information of the other cell is used to transmit a D2D discovery signal in the frequency band of the other cell, and the D2D discovery resource information for the other cell is a D2D transmission power parameter related to transmission of the D2D discovery signal in the UE. to include
Serving base station in a communication system supporting the D2D method characterized in that. 20. The method of claim 19,
The serving base station in a communication system supporting the D2D scheme, characterized in that the D2D transmission power parameter is related to a corresponding D2D discovery resource configuration.

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