Communication device, control method, and program

Abstract

A communication device communicating using a sidelink communication function in a 3rd generation partnership project (3GPP) cellular communication standard transmits a discovery message including information indicating a predetermined function to be performed using the sidelink communication function, and searches for another communication device capable of performing the predetermined function.

Description

Technical Field

[0001] The present invention relates to a communication device, a control method, and a program. Background Art

[0002] As a cellular communication standard defined by the Third Generation Partnership Project wireless communication standards such as Long-Term Evolution (LTE) and New Radio (NR) have been defined. These standards include standards related to sidelink communication (3GPP standards, TS 36.300, TS 38.300, etc.), in which terminal devices (UEs) communicate directly with each other without intervention of a mobile communication network (core network).

[0003] In communication via a base station, communication between the base station and a UE is performed under the control of the base station. Therefore, communication between a UE and another UE can be performed under the control of the base station by a communication method according to the functions between the UEs. On the other hand, in sidelink communication, since there is no intervention of a base station, it is assumed that processing such as specifying a partner device and determining a communication method is performed between UEs. For example, PTL 1 describes a method of performing communication by using an appropriate communication method by exchanging sidelink capability information between user devices. PTL 2 describes a method of connecting a UE outside the communicable range of a base station to a relay device installed within the communicable range via a sidelink and allowing communication with the base station. PTL 3 describes that a communication device sends a search request message to devices around it, and network settings are performed in another device selected by a user from the devices that are the sources of responses to the message.

[0004] Citation List

[0005] Patent Documents

[0006] PTL 1: Japanese Patent Laid-Open No. 2022-071153

[0007] PTL 2: Japanese Patent Laid-Open No. 2021-078140

[0008] PTL 3: Japanese Patent Laid-Open No. 2002-236628 Summary of the Invention

[0009] Technical Problem

[0010] Sidelink communication can be used in various modes. At this time, whether sidelink communication can be performed in the mode requested by the UE depends on the state of another UE that is the connection destination. As in PTL 3, even if a user selects another UE as the connection destination, if the user does not know whether that other UE can perform the desired sidelink communication, it is not easy to make an appropriate selection. Therefore, the efficiency of sidelink communication may degrade.

[0011] Solution to the problem

[0012] The present invention provides a technique that enables efficient execution of sidelink communication.

[0013] A communication device according to one aspect of the present invention is a communication device including: a communication unit configured to perform communication using a sidelink communication function in a cellular communication standard in the 3rd Generation Partnership Project (3GPP); and a search unit configured to search for another communication device capable of performing the predetermined function after the device is connected for the sidelink communication function by transmitting a discovery message including information indicating a predetermined function to be performed using the sidelink communication function.

[0014] Advantageous effects of the invention

[0015] According to the present invention, sidelink communication can be efficiently performed.

[0016] Other features and advantages of the present invention will become clear from the following description in conjunction with the accompanying drawings. Note that in all the drawings, the same reference numerals denote the same or similar components. Description of the drawings

[0017] The drawings incorporated in and constituting a part of the specification illustrate embodiments of the present invention and, together with the description, are used to explain the principles of the present invention.

[0018] Figure 1 is a diagram showing an example of the configuration of a wireless communication system;

[0019] Figure 2 is a block diagram showing an example of the hardware configuration of a communication device (UE);

[0020] Figure 3 is a block diagram showing an example of the functional configuration of a communication device (UE);

[0021] Figure 4 is a view showing an example of the format of a message;

[0022] Figure 5A is a table showing an example of the structure of information elements in a message;

[0023] Figure 5B is a view showing an example of the structure of information elements in a message;

[0024] Figure 6 is a flowchart showing an example of the process of processing performed by a UE that sends a discovery message;

[0025] Figure 7 is a flowchart showing an example of the process of processing performed by a UE that receives a discovery message;

[0026] Figure 8A is a view for illustrating an example of an operation associated with D2D communication;

[0027] Figure 8B is a view for illustrating an example of an operation associated with D2D communication;

[0028] Figure 8C is a view for illustrating an example of an operation associated with D2D communication;

[0029] Figure 9A is a sequence diagram showing an example of the process of processing associated with D2D communication;

[0030] Figure 9B is a sequence diagram showing an example of the process of processing associated with D2D communication;

[0031] Figure 9C is a sequence diagram showing an example of the process of processing associated with D2D communication;

[0032] Figure 10 is a view for illustrating an example of an operation associated with UE relay communication;

[0033] Figure 11 is a sequence diagram showing an example of the process of processing associated with UE relay communication;

[0034] Figure 12 is a view for illustrating an example of an operation associated with network relay communication;

[0035] Figure 13 is a sequence diagram showing an example of the process of processing associated with network relay communication;

[0036] Figure 14 is a view showing an example of the format of a message;

[0037] Figure 15 is a table for illustrating services stored in a message and their associated information;

[0038] Figure 16It is a flowchart showing an example of a process executed by a UE on the receiving side that discovers a message;

[0039] Figure 17 It is a view for explaining a use case of the system;

[0040] Figure 18 It is a sequence diagram showing an example of a process executed by the system;

[0041] Figure 19 It is a flowchart showing an example of a process executed by a UE that sends a discovery message;

[0042] Figure 20 It is a flowchart showing an example of a process executed by a UE that receives a discovery message; and

[0043] Figure 21 It is a view showing an example of the format of a message. Detailed implementation

[0044] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments are not intended to limit the scope of the claimed invention. Multiple features are described in the embodiments, but the invention is not limited to requiring all such features, and multiple such features can be appropriately combined. In addition, in the drawings, the same or similar configurations are given the same reference numerals, and their repeated descriptions are omitted.

[0045] [First Embodiment]

[0046] (System Configuration)

[0047] Figure 1 It shows an example of the configuration of a wireless communication system according to this embodiment. This wireless communication system is, for example, a system that performs wireless communication according to a cellular communication standard such as LTE or NR in the Third Generation Partnership Project and includes a base station 101 and terminals (UEs 111 to 117). The UEs 111 to 117 are configured to perform sidelink communication defined in the wireless communication standard.

[0048] The UEs 111 to 117 can perform communication in various modes using sidelink communication. For example, UE 111 can perform direct wireless communication with UE112 without intervening in the base station 101. In addition, for example, in TS23.304, there is a standard in which UE 113, which can directly communicate with the base station 101, can relay communication between the base station and UE 114, which cannot directly communicate with the base station 101. In addition, in In Technical Report TR 23.752, the configuration in which another UE 116 relays the communication between UEs 115 and 117 that cannot directly communicate with each other is the main research content. By using sidelink communication, (1) direct communication between UEs can be performed; (2) relaying between the network and a UE outside the communicable range of the base station can be performed; and (3) relaying of communication between UEs that are outside the directly communicable range can be performed. Note that hereinafter, (1) will sometimes be referred to as D2D communication, network relaying, or UE relaying.

[0049] The UE detects other UEs that are candidates as connection destinations and selects another UE from the candidates as the connection destination. For example, consider the case where UE 114, which is outside the communicable range of base station 101, attempts to establish a connection with base station 101 using network relaying. In this case, by establishing a connection with UE 113 that is connected to base station 101, UE 114 can communicate with base station 101 via UE 113. On the other hand, assume that, for example, UE 114 discovers UE 115 that exists nearby as a candidate for a connection destination for sidelink communication. Also assume that UE 115 is not connected to base station 101 and thus cannot provide network relaying. However, conventionally, UE 114 can only know whether UE 115 can provide network relaying after establishing a connection with UE 115. Therefore, UE 114 identifies that UE 115 cannot provide network relaying after establishing a connection with UE 115, and then disconnects the sidelink. Then, UE 114 needs to re - execute the process starting from the process of detecting another UE that can provide network relaying. As described above, since the UE cannot know the status of another UE as a connection destination, the process may become complicated. Regarding D2D communication and UE relaying, conventionally, the UE cannot know in advance whether another UE can perform such communication.

[0050] In view of the above problems, this embodiment provides a method that allows the UE to pre - specify whether another UE that is a candidate as a connection destination can perform sidelink communication in a mode requested by its own device.

[0051] In this embodiment, the UE sends a discovery message by including information indicating the mode of sidelink communication requested by its own device and additional information such as the status of communication in its own device. This discovery message is used to detect another UE or allow another UE to detect its own device. For example, the UE may send a discovery message that includes information indicating which communication method among D2D communication, network relay, and UE relay is to be used to perform sidelink communication with the searched-for partner. The UE may send a discovery message that includes information capable of specifying whether its own device can perform D2D communication, network relay, and UE relay as information indicating the status of communication, etc. Note that this information may be included in a response message in response to the discovery message. In an example, the UE that sends the discovery message may send a discovery message that includes information indicating the requested sidelink communication method. On the other hand, the UE that sends the response message may include, in the response message, information indicating the communication methods executable in the UE as information indicating the status of communication. Note that it can send a response message only when another UE can perform sidelink communication using the communication method requested by the UE. By receiving the discovery message from the UE, another UE can determine which communication method among D2D communication, network relay, and UE relay is requested. By receiving the response message from other UEs, the UE can specify another UE that can perform communication using the communication method requested by its own device. In addition, only a UE that can perform sidelink communication in the mode requested by the UE indicated as the source in the discovery message can send a response message to the discovery message.

[0052] Note that the configuration and operation of a terminal (UE) that performs sidelink communication in a cellular communication standard will be described below, but the following discussion can be applied to a wireless communication device that is a more general version of the UE and performs similar communication. In addition, the following configurations and operations are merely examples, and any changes and modifications can be made without departing from its scope.

[0053] (Device Configuration)

[0054] Figure 2 An example of the hardware configuration of a communication device operating as a UE according to this embodiment is shown. Note that Figure 2 the configuration shown in Figure 2 is merely an example, and the UE can be implemented with a hardware configuration different from the hardware configuration shown in Figure 2 . For example, the UE does not need to include a part of the hardware configuration shown in

[0055] The storage unit 201 includes memories such as read-only memory (ROM) and random access memory (RAM), and stores programs for performing various operations to be described later and various information such as communication parameters for wireless communication. Note that, in addition to memories such as ROM and RAM, the storage unit 201 may also include storage media such as floppy disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, or DVDs. The storage unit 201 may include a plurality of memories.

[0056] The control unit 202 is formed of, for example, a processor such as a CPU or MPU, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), etc. Note that, CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Micro Processing Unit. For example, the control unit 202 controls the entire UE by executing the programs stored in the storage unit 201. Note that the control unit 202 may also control the UE through the cooperation of the programs stored in the storage unit 201 and the OS (operating system). The control unit 202 may include a plurality of processors such as a multi-core processor.

[0057] The control unit 202 can control the functional unit 203 to implement a predetermined function, such as an impact detection function, an image capture function, a printing function, or a projection function. The functional unit 203 is configured to include hardware for the UE to perform a predetermined process. For example, if the functional unit 203 has an image capture function, then it includes an optical lens unit, an optical system for controlling an aperture, zoom, focus, etc., and an image sensor for converting light (video) introduced via the optical lens unit into an electrical video signal. Generally, a CMOS (Complementary Metal Oxide Semiconductor) sensor or a CCD (Charge Coupled Device) is used as the image sensor. Under the control of the control unit 202, the functional unit 203 causes the image sensor to convert an image of object light formed by a lens included in the functional unit 203 into an electrical signal, perform noise reduction processing, etc., and output digital data as image data. The image data is recorded in the storage unit 201 according to the DCF (Design rule for Camera File system) standard. If the functional unit 203 has an impact detection function, then it includes a sensor. If the sensor detects an impact or jitter at a predetermined level or higher, then the functional unit 203 notifies the control unit 202 of the detection result. Note that, in this embodiment, the UE can be a smart phone, a digital still camera, a network camera, a printer, an in-vehicle device, etc. having an image capture function. However, the UE is not limited to these, and for example, it can be a projector that projects an image on a projection part, a head-mounted display that provides an image based on data received from the outside to a user, etc. Alternatively, the UE can be a wearable device such as a smart watch or wearable glasses having a function of projecting an image on a projection surface (such as glass or a user's retina). Note that the in-vehicle device refers to a standard control device incorporated in a vehicle such as an automobile, an in-vehicle navigation device installed in a vehicle such as an automobile, a driving record device installed in a vehicle such as an automobile and recording video during driving, etc.

[0058] The input unit 204 accepts various operations from the user. The output unit 205 performs various outputs to the user. In this example, the output of the output unit 205 includes at least one of a display on a screen, an audio output from a speaker, a vibration output, etc. Note that both the input unit 204 and the output unit 205 can be implemented by one module (such as a touch panel).

[0059] The communication unit 206 is configured to include hardware (such as a radio frequency (RF) chip, a baseband chip, etc.) for performing wireless communication conforming to the cellular communication standard. The communication unit 206 controls the corresponding antenna 207 to transmit / receive radio signals for wireless communication. Note that, Figure 2A configuration including an antenna 207 is shown, but multiple antennas may be used. For example, in addition to communicating with the base station, the communication unit 206 is also configured to perform sidelink communication with another UE.

[0060] Figure 3 is a block diagram showing an example of the functional arrangement of a communication device (UE). Some (in some cases, all) of the functional blocks to be described for the communication device can be replaced by other functional blocks that implement the same function, some functional blocks can be omitted, and more functional blocks can be added. One functional block to be described below can be divided into multiple functional blocks, and multiple functional blocks can be integrated into one functional block. The UE includes a function control unit 301, a storage control unit 302, a discovery message generation unit 303, a discovery message analysis unit 304, and a communication control unit 305. For example, the function control unit 301 controls the operation of each function of the UE by causing the control unit 202 to execute a program stored in the storage unit 201. For example, the storage control unit 302 performs various control operations related to the storage of information such as storing information in the storage unit 201 and extracting information from the storage unit 201. The discovery message generation unit 303 generates a discovery message to be sent to detect another UE. In some cases, the discovery message generation unit 303 generates a response message to a discovery message received from another UE. The discovery message analysis unit 304 analyzes the discovery message sent from another UE. The communication control unit 305 controls the communication unit 206 to perform communication with the base station or sidelink communication with another UE. Note that the communication control unit 305 is configured to send the discovery message generated by the discovery message generation unit 303 or supply the discovery message sent from another UE and received to the discovery message analysis unit 304.

[0061] (Structure of the discovery message)

[0062] Subsequently, reference will be made to Figure 4 、 Figure 5A and Figure 5B to describe examples of the structures of the discovery message and the response message. Figure 4 Shows an exemplary format of the discovery message and the response message. Note that the discovery message will be described below, but unless otherwise specified, the response message may include the same content. Note that the discovery message is a message sent when the UE performs the detection process of other UEs, and the response message is a message for allowing another UE that has received the discovery message to detect the presence of its own device. This embodiment assumes that the discovery message and the response message for the 5G ProSe direct discovery process have Figure 4 、 Figure 5A and Figure 5BThe format shown in the figure. Each message is used to discover another adjacent UE supporting 5G ProSe through direct wireless transmission between two UEs using 5G NR (New Radio) technology. Note that ProSe is the abbreviation of Proximity Service.

[0063] In message 401, the destination Layer-2 ID field stores the Layer-2 ID indicating the destination of the message. In the example, in the destination Layer-2 ID field of the discovery message, for example, information indicating broadcast can be set, while information indicating another individual UE as the destination is not set. On the other hand, in the destination Layer-2 ID field of the response message, the ID of the UE that is the source of the discovery message can be set. The source Layer-2 ID field stores the Layer-2 ID indicating the source of the message. The frame type field stores information indicating the type of the message. For example, information indicating whether the message is a discovery message or a response message is stored in the frame type field. In the frame type field of the discovery message, "Prose direct discovery" is set.

[0064] In the connection capability field 402, information indicating the mode of sidelink communication requested by the UE (the UE performing the detection process of other UEs) that is the source of the discovery message 401 is set. For example, as Figure 4 shown, as information indicating the mode of sidelink communication, bits for setting "network relay", "UE relay", and "D2D" as sidelink communication methods can be prepared. Among these communication methods, the bit corresponding to the communication method requested by the UE that is the source of the discovery message is set to "1", while the bit corresponding to the unrequested communication method is set to "0". Note that this is just an example, and bits corresponding to modes other than these communication methods can be prepared, or the bit corresponding to the requested mode can be set to "0", while the bit corresponding to the unrequested mode can be set to "1". Note that if the UE wants to obtain all information of other UEs around its own device, then nothing needs to be set in the connection capability field (for example, all bits are set to "0").

[0065] Note that if another UE receives a discovery message with nothing set in the connection capability field 402, then that UE may return a response message with the sidelink communication method executable by its own device set. Note that if another UE receives a discovery message, then that UE sends a response message specifying the ID of the UE that is the source of the discovery message in the destination Layer-2 ID field. In this case, the sidelink communication method executable by the UE sending the response message may be set in the connection capability field 402 of the response message. For example, the bits corresponding to the sidelink communication methods executable by the UE may be set to "1", while the bits corresponding to the sidelink communication methods not executable by the UE may be set to "0". Note that "0" may indicate an executable sidelink communication method, while "1" may indicate a non-executable sidelink communication method. If a UE can execute multiple communication methods, then each bit corresponding to the multiple methods may be set to a value indicating that the method is executable. On the other hand, after receiving a discovery message specifying the requested communication method, if the UE can perform sidelink communication using the requested communication method, the UE may return a similar response message. Note that in this case, nothing needs to be set in the connection capability field 402 of the response message. In this case, based on the reception of a response message specifying the ID of its own device in the destination Layer-2 ID field, the UE that sent the discovery message can estimate that sidelink communication can be performed using the requested communication method. Note that if sidelink communication cannot be performed using the requested communication method specified in the discovery message, the UE does not return any response message.

[0066] In the connection capability information field 403, the required information is set according to the executable sidelink communication method. For example, in the connection capability information field 403, information indicating an identifier and a carrier associated with the base station to which the UE sending the message is currently connected, base station information (such as the received radio field strength of the signal from the base station), the terminal identifier of the UE, etc. are stored. The identifier associated with the base station may be, for example, a physical cell identifier. The information indicating the carrier may be information capable of specifying the network, such as a public land mobile network (PLMN) identifier. The information indicating the carrier may be, for example, information capable of specifying the used frequency band, such as an absolute radio frequency channel number (ARFCN). The carrier information may be information of the communication operator operating the base station. It should be noted that the base station information may be formed to include at least one of the above identifier, carrier (used frequency band / communication operator) information, and received radio field strength. In addition to or instead of this, other information may also be included. For example, the terminal identifier may be an identifier associated with the communication with the base station, such as a temporary mobile subscriber identity (TMSI). Alternatively, the terminal identifier may be any other identifier capable of specifying the UE. It should be noted that these are only examples. For example, as information associated with UE relaying, information capable of specifying another connected UE may be set in the connection capability information field 403.

[0067] Reference will be made to Figure 5A and Figure 5B describe examples of the information set in the connection capability information field 403. Figure 5A Examples of the information items set in the connection capability information field 403 are shown. As an example, an operation status identifier, a base station identifier, a connected terminal identifier, a base station radio field strength, connected base station information, etc. are set in the connection capability information field 403. Each of these pieces of information is added with an index from 1 to 5, and this index is used in the connection capability information field 403 to declare which piece of information to send. For example, when in Figure 5BWhen "01" is set in item 501, the specified operation status identifier is located after the subsequent item 502. In this case, for example, "01" indicating that the function of performing network relay is active is set in item 502. Note that whether a function is active is specified separately from the information indicating whether the function is supported. That is, in the case where the network relay function is supported but not active, the corresponding information in the connection capability field can be set to "01", and the operation status identifier can be set to "02". The base station identifier is described in the subsequent item 503. The base station identifier can have, for example, a fixed length, but can also have a variable length. For example, if variable-length information is used, the length of the information, such as "06", is indicated in item 504, and the base station identifier "XXXXXX" is set in the subsequent item 505. In addition, "05" indicating connection base station information is set in item 506, and the length of the information is indicated as "04" in item 507. The connection base station information is formed to represent more information by expanding the index. For example, "01" is set in item 508, and "01" indicating that the UE as the message source is connected to the base station of Company A is set in the subsequent item 509. In addition, "02" is set in item 510, and "51" indicating that the used frequency band is n78 is set in the subsequent item 511. Note that these are just examples, and another form of information can be set in the connection capability information field 403.

[0068] Return reference Figure 4 , the frame payload field stores the body of the information exchanged between devices using the message.

[0069] (Process of processing)

[0070] Will refer to Figure 6 Describe an example of the process of the processing performed by the UE that sends the discovery message. Note that this processing is performed, for example, using the discovery message generation unit 303. Figure 6 The processing shown in Figure 6 is just an example. For example, some processing steps can be omitted, or

[0071] First, the UE generates the discovery message as described above and sends it to the periphery of the UE (step S601). In the example, if the UE obtains all the information of the UEs around it, then the UE does not set anything in the connection capability field and sends the discovery message. For example, if the UE only detects another UE that can perform D2D communication (supports the D2D communication function), then the UE sets the bit corresponding to D2D communication to a predetermined value in the connection capability field. Similarly, if the UE detects another UE that can perform UE relay or network relay, then the UE sets the corresponding bit in the connection capability field to a predetermined value. Note that the UE can set the bit corresponding to the second communication method requested to use among one or more first communication methods supported by its own device to a predetermined value. That is, for communication methods not supported by its own device, the UE can be prevented from setting the corresponding bit to a predetermined value. After that, the UE waits to receive a response message from another UE (step S602). After receiving the response message from another UE, the UE confirms the value of the connection capability field in the message (step S603). As described above, the connection capability field in the response message stores information indicating which of D2D communication, UE relay, and network relay can be performed by another UE that is the source of the response message. Therefore, by analyzing the connection capability field, the UE can specify which communication method can be used by another UE that is the source of the response message to perform sidelink communication.

[0072] For example, now the processing in the case where the UE expects to perform D2D communication with another UE will be described. The UE confirms that there is another UE around that can perform D2D communication (step S604). Note that if there is no other UE around that can perform D2D communication, then the UE can directly end the processing. If there is a UE around that can perform D2D communication, then the UE determines whether to perform D2D communication with the neighboring UE. For example, if both the UE and the neighboring UE are connected to the same base station, then the UE may be able to perform high-speed communication by communicating via the base station without performing D2D communication. This situation includes, for example, the case where the frequency band used to connect to the base station is a frequency band such as millimeter wave that can ensure a sufficiently wide signal bandwidth and can use a large amount of resources. Therefore, in this embodiment, if the UE is currently connected to the same base station as another UE, then it is determined not to perform D2D communication.

[0073] If the UE is not within the communicable range of any base station (Yes in step S605), then the UE is not connected to the same base station as the base stations of the surrounding UEs, and thus D2D communication is performed (step S607). Alternatively, if the UE is currently connected to any one base station (or is located in a cell provided by the base station), then the UE confirms the connection capability information field in the response message. Then, the UE obtains the identifier of the base station to which the other UE that has sent the response message is currently connected (or is located), and determines whether the other UE is within the communicable range of the same base station as the base station of its own device (step S606). Then, if the UE and the other UE are within the communicable range of the same base station (Yes in step S606), then the UE does not perform D2D communication; otherwise (No in step S606), the UE performs D2D communication (step S607). Note that, for example, if the frequency band used by the base station to which the UE is currently connected (or is located) is not a predetermined frequency band such as a millimeter wave frequency band, then even if the other UE is currently connected to (or is located in) the same base station, the UE may determine to perform D2D communication. Alternatively, for example, if the radio quality of the base stations to which its own device and the other UE are currently connected (or are located) is lower than a predetermined value, then the UE may determine to perform D2D communication. Even if the UE is connected to a base station different from the base station of the other UE, if each of its own device and the other UE can perform high-capacity communication with the base station, then the UE may also determine not to perform D2D communication. As described above, whether to perform D2D communication can be determined based on various criteria, and this is not limited to the above determination process based on whether the UE is connected to the same base station.

[0074] Next, for example, the processing in the case where a UE desires another UE to relay communication with a communication partner UE through UE relay communication will be described. The UE confirms the connection capability field in the received response frame, thereby confirming the presence of another UE that can perform UE relay communication in the vicinity (step S608). In the example, the UE that has established a connection with another UE through sidelink communication or the UE belonging to a group including another UE for performing sidelink communication transmits a response frame indicating that UE relay communication is executable. If there is no such another UE, the UE directly ends the processing. On the other hand, if there is another such UE in the vicinity, the UE analyzes the connection capability information field in the response frame transmitted from the other UE. Then, the UE determines whether there is another UE among the other UEs that are the transmission sources of the response frame and that can perform sidelink communication with the communication partner UE of its own device (step S609). Then, if there is another UE in the vicinity that can perform sidelink communication with the communication partner UE ( "Yes" in step S609), the UE establishes a connection with that UE and performs UE relay communication using sidelink communication (step S610). On the other hand, if there is no another UE in the vicinity that can perform sidelink communication with the communication partner UE ( "No" in step S609), the UE directly ends the processing (step S610).

[0075] Finally, for example, the processing in the case where a UE desires another UE to relay communication with a base station through network relay communication will be described. The UE confirms the connection capability field in the received response frame, thereby confirming the presence of another UE in the vicinity that can perform UE relay communication (step S611). Then, the UE analyzes the connection capability information field in the response frame sent from such another UE. The connection capability information field stores information such as the identifier of the base station as the connection destination, the received radio field strength from the base station, the carrier operating the base station, and the frequency band for communication, for example. Based on this information, the UE decides which of the other UEs that can perform network relay communication to connect to. Suppose the UE is concerned about whether the radio quality with the base station is satisfactory and selects another UE with a satisfactory received radio strength from the base station as the connection destination (step S612). Note that this is merely an example, and for example, the UE may only allow connection to another UE on a specific carrier (e.g., the carrier subscribed to by its own device). Alternatively, for example, the UE may decide to preferentially connect to another UE connected to the base station that obtains a received radio strength equal to or higher than a predetermined value and that uses a high-frequency band capable of broadband transmission. The UE may select another UE as the connection destination according to the priority order obtained by inputting the information stored in the connection capability information field into a predetermined function. After that, the UE connects to the selected other UE to perform network relay communication (step S613). Note that the other UE may be in a state of being currently connected to the base station or in a waiting state. If the other UE is in a waiting state, then when the UE receives a connection request for network relay communication, the UE may establish a connection with the base station in the waiting state.

[0076] Subsequently, an example of the process of the processing performed by the UE that receives the discovery message and returns the response message will be described with reference to Figure 7 Note that this processing is performed using, for example, the discovery message analysis unit 304. Figure 7 The processing shown in Figure 7 is merely an example. For example, some processing steps may be omitted, and processing steps not shown in

[0077] When receiving a discovery message sent from another UE in the vicinity (step S701), the UE analyzes the connection capability field included in the message and confirms the sidelink communication method requested by the other UE (step S702).

[0078] If the other UE requests D2D communication (step S703), then the UE includes in the connection capability field of the response message information indicating whether its own device can perform (support) D2D communication (step S704). For example, if the own device supports D2D communication, then the UE sets the bit corresponding to D2D communication in the connection capability field to "1". Similarly, if the other UE requests UE relay communication (step S706), then the UE includes in the connection capability field of the response message information indicating whether its own device supports UE relay communication (step S707). If the other UE requests network relay communication (step S709), then the UE includes in the connection capability field of the response message information indicating whether its own device supports network relay communication (step S710). In addition, if the UE receives a discovery message from another UE that does not specify any particular sidelink communication method (step S712), then the UE includes in the connection capability field of the response message the functions supported by its own device (step S713).

[0079] In addition, the UE includes in the connection capability information field additional information associated with the supported communication method indicated in the connection capability field (steps S705, S708, S711, or S714). For example, if the UE includes in the response message information indicating that its own device supports D2D communication, then the UE sets in the connection capability information field the base station identifier associated with the base station to which the UE is currently connected or where it is located (step S705). If the UE includes in the response message information indicating that its own device supports UE relay communication, then the UE sets in the connection capability information field the terminal identifier of another connected UE that can be specified (step S708). If the UE includes in the response message information indicating that its own device supports network relay communication, then the UE sets in the connection capability information field the base station information related to the base station to which the UE is currently connected or where it is located (step S711). Note that the base station information includes, for example, the base station identifier, the received radio field strength, carrier information, frequency band, etc. If the UE receives a discovery message that does not specify any particular sidelink communication method, then the UE sets in the connection capability information field all the additional information related to the functions supported by its own device (step S714). Note that the UE may generate and send a single response message including each piece of information related to multiple communication methods, but may also generate and send separate response messages for each communication method.

[0080] (Operation Example)

[0081] Subsequently, some operation examples in the above system will be described. First, an example of the processing in the case where the UE requests D2D communication will be described. Figures 8A to 8C Some cases of requesting D2D communication are shown. Figures 9A to 9CEach shows an example of the process of processing in each case. For example, D2D communication can be used by vehicles each including a UE having sidelink communication capabilities to exchange information between vehicles to perform platooning. D2D communication can also be used when such vehicles exchange information about road information by directly communicating with road-mounted equipment (traffic lights, etc.) including a UE having sidelink communication capabilities.

[0082] For example, in Figure 8A , UE 801 will perform D2D communication. In this example, UEs 802 and 803 exist in the vicinity of UE 801. UE 803 is within the range of cell 805 formed by base station 804 and can communicate with base station 804. In this state, UE 801 sends a discovery message to its vicinity without specifying any particular communication method in the connection capability field, and UEs 802 and 803 each receive the message (F901). In response to the discovery message, UE 802 sends a response message to UE 801, in which a value indicating that D2D communication is possible and the UE is not within the range of any base station is set (F902). UE 803 sets information indicating that network relay communication is possible and base station information about base station 804, and sends a response message to UE 801 (F903). In this case, since UE 801 expects D2D communication, it determines whether to perform D2D communication with UE 802 as a communication partner. If the example of the process shown in Figure 6 is used, since the own device is not within the communicable range of any base station ("Yes" in step S605), UE 801 determines to perform D2D communication with UE 802, and thus performs connection processing (F904). Note that each of UEs 802 and 803 can include in the additional information information indicating whether the supported communication function is active. This allows UE 801 to specify whether communication can be immediately started through the communication functions supported by each UE.

[0083] For example, in Figure 8BIn this case, UE 811 will perform D2D communication. UE 812 is present in the vicinity of UE 811. UE 811 is within the range of cell 815 formed by base station 813 and can communicate with base station 813. In addition, UE 812 is within the range of cell 816 formed by base station 814 and can communicate with base station 814. In this state, UE 811 sends a discovery message to its vicinity without specifying any particular communication method in the connection capability field, and UE 812 receives this message (F911). In response to the discovery message, UE 812 sends a response message to UE 811, in which values indicating that D2D communication is possible and that the UE is within the range of base station 814 are set (F912). Thus, UE 811 recognizes that it can perform D2D communication with UE 812 and determines whether to perform D2D communication with UE 812 as a communication partner. If the processing example shown in Figure 6 is used, then since the own device is within the communicable range of base station 813 and UE 812 is within the communicable range of a different base station 815 from base station 813 ("No" in step S606), UE 811 determines to perform D2D communication with UE 812. Then, UE 811 performs connection processing with UE 812 (F913). Note that UE 812 may include in the additional information information indicating whether the supported D2D communication function is active. This allows UE 811 to specify whether D2D communication can be immediately started.

[0084] For example, in Figure 8C this case, UE 821 will perform D2D communication. UE 822 is present in the vicinity of UE 821. In addition, both UE821 and 822 are within the range of cell 824 formed by base station 823 and can communicate with base station 823. In this state, UE 821 sends a discovery message to its vicinity without specifying any particular communication method in the connection capability field, and UE 822 receives this message (F921). In response to the discovery message, UE 822 sends a response message to UE 821, in which values indicating that D2D communication is possible and that the UE is within the range of base station 823 are set (F922). Thus, UE 821 recognizes that it can perform D2D communication with UE 822 and determines whether to perform D2D communication with UE 822 as a communication partner. If the processing example shown in Figure 6If it is an example of the process shown in , since the own device is within the communicable range of the base station 823 and the UE 822 is also within the communicable range of the same base station 823 (Yes in step S606), the UE 821 determines not to perform D2D communication with the UE 822. Then, the UE 821 does not perform connection processing (F923) with the UE 822 and performs communication via the base station 823, for example.

[0085] As described above, the UE can easily specify another UE with which D2D communication can be performed and can perform D2D communication with the other UE. In addition, based on the additional information included in the response message, the UE can appropriately determine whether to perform D2D communication. For example, the UE can determine not to perform D2D communication with another UE connected to the same base station.

[0086] Next, an example of the process in the case where a first UE that requests support for UE relay communication requests a second UE to perform relay communication will be described. Figure 10 The case where UE relay communication is requested is shown, and Figure 11 An example of the process of the process in this case is shown. Note that UE relay can be used when vehicles each including a UE with sidelink communication function outside the communicable range of the base station exchange road information between the vehicles using UE relay. When road-mounted equipment (such as traffic signals) including a UE with sidelink communication function supports UE relay, communication between vehicles each including a UE with sidelink communication function outside the communicable range of the base station can be supported.

[0087] In Figure 10 UE 1001 will communicate with UE 1003. UE 1002 and 1004 are in the vicinity of UE 1001, and UE 1003 and UE 1005 are within a range where UE 1001 cannot directly connect. Note that UE 1002 can communicate directly with UE 1003, and UE 1004 can communicate directly with UE 1005. It is assumed that UE 1002 and 1004 support UE relay communication.

[0088] To search for another UE that can relay communication with UE 1003 using the UE relay communication function, UE 1001 sends a discovery message in which UE relay (F1101) is set in the connection capability field. When receiving the discovery message, each of UE 1002 and 1004 sends a response message (F1102 and F1103) indicating that its own device supports the UE relay communication function to UE 1001. Note that UE 1002 may include the terminal identifier of UE 1003 as additional information in the connection capability information field of the response message. UE 1004 may include the terminal identifier of UE 1005 as additional information in the connection capability information field of the response message. When receiving the response message, UE 1001 may specify that it can communicate with UE 1003 through the UE relay communication of UE 1002 and that it can communicate with UE 1005 through the UE relay communication of UE 1004. Then, since UE 1001 expects to communicate with UE 1003, it selects UE 1002 that can communicate with UE 1003 through UE relay communication as the connection destination, and thus performs connection establishment processing (F1104). Note that each of UE 1002 and 1004 may include in the additional information information indicating whether the supported UE relay communication function is active. This allows UE 1001 to specify whether communication with the desired partner device can be immediately started through the UE relay communication function.

[0089] As described above, the UE can easily specify another UE that can perform UE relay communication and can receive an offer of UE relay communication from that other UE. Note that based on the additional information included in the response message, the UE can appropriately select another UE that allows communication with an appropriate partner device. Therefore, the UE can appropriately select another device that supports the UE relay communication function and thus perform communication with the desired partner device.

[0090] Next, an example of processing in the case where a first another UE that requests support for the network relay communication function relays communication with a second another UE will be described. Figure 12 The case of requesting network relay communication is shown, and Figure 13 an example of the process of the processing in this case is shown. The network relay function can be used, for example, to extend the communicable range of a base station. A vehicle that includes a UE having a sidelink communication function and exists outside the communicable range of the base station can be connected to the base station through the relay of communication including a road-mounted device that includes a UE having a sidelink communication function and supports the network relay function. Therefore, a vehicle that exists outside the communicable range of the base station can access the Internet or the like to obtain road information or the like.

[0091] InFigure 12 In this case, UE 1201 searches for another UE that supports the network relay function to perform connection to the base station. UEs 1202, 1203, and 1204 are present in the vicinity of UE 1201. UEs 1202 and 1203 are within the communicable range 1206 of base station 1205 and support network relay. On the other hand, UE 1204 is outside the communicable range 1206 and does not support network relay. The radio field strength from base station 1205 in UE 1202 is higher than the radio field strength from base station 1205 in UE 1203.

[0092] To search for another UE that supports the network relay communication function, UE 1201 sends a discovery message in which network relay is set in the connection capability field (F1301). Since each of UEs 1202 and 1203 supports the network relay function, the UEs return a response message to UE 1201, which includes information indicating that the own device supports the network relay function (F1302 and F1303). Note that each of UEs 1202 and 1203 sends a response message that includes additional information such as the base station identifier of base station 1205 to which the UE is currently connected or located, the received radio field strength, carrier information, and used frequency band. Note that each of UEs 1202 and 1203 may include in the additional information information indicating whether the supported network relay function is active. This allows UE 1201 to determine whether communication with the base station can be immediately started through the network relay function. On the other hand, since UE 1204 does not support the network relay function, it does not return a response message.

[0093] After receiving the response messages from each of UEs 1202 and 1203, UE 1201 can specify that each of UEs 1202 and 1203 supports the network relay function. Then, UE 1201 specifies the information of the base station to which each of UEs 1202 and 1203 is connected from each response message, and for example, selects UE 1202 with a satisfactory received radio field strength as the connection destination, and thus performs connection processing with UE 1202 (F1304).

[0094] As described above, the UE can easily specify another UE that can perform network relay communication and can receive the provision of network relay communication by the other UE. Note that, for example, based on the additional information included in the response message, the UE can appropriately select another UE that allows communication with the base station with a more satisfactory radio quality. Therefore, the UE can appropriately select another device that supports the network relay communication function and thus perform communication with the base station.

[0095] In the above-described embodiments, a method has been described in which a UE that has received a discovery message returns a response message in which supported communication methods are set. However, the present invention is not limited thereto. For example, even if the UE does not receive a discovery message, the UE may periodically transmit a signal such as a notification signal in which supported communication methods are set. In an environment where such a signal is transmitted, the UE can easily specify another UE that can perform sidelink communication by the communication method requested by its own device by detecting signals transmitted by other UEs in the vicinity.

[0096] [Second Embodiment]

[0097] The above-described embodiments have illustrated a method in which a UE can specify another UE in its vicinity that can perform sidelink communication by the communication method requested by its own device. This embodiment provides a method in which a UE specifies another UE that can provide the service requested by its own device and can perform sidelink communication, and performs the service. Note that the device configuration is the same as in the first embodiment.

[0098] In this embodiment, a discovery message in the format shown in Figure 14 is used. In this format, the destination Layer-2 ID field, the source Layer-2 ID field, and the frame type field are the same as those described in the reference Figure 4 . That is, this embodiment assumes that the discovery message for the 5G ProSe direct discovery process has the format shown in Figure 14 . The discovery message used in this embodiment includes a "service" field after the frame type field. The service field stores information indicating the service requested to be performed by another UE by the UE that is the source of the discovery message. The frame payload field stores information corresponding to the service field. In this embodiment, the UE can generate a discovery message and transmit the discovery message, and store, for example, "record" in the service field and the location information obtained by its own device in the frame payload field in the discovery message. When receiving the discovery message, the UE can generate a response frame in the format shown in Figure 14 as needed and return the response frame. In the example, when receiving the discovery message, the UE returns a response frame in which information indicating the service that its own device can perform (the service requested by the UE that has sent the discovery message) is stored in the service field. In addition, the UE can store information corresponding to the service in the frame payload field of the response frame. That is, in this embodiment, information indicating the service that its own device can perform is stored in the response frame of the discovery message for the 5G ProSe direct discovery process.

[0099] Figure 15 shows an example of the information set in the discovery message. Note that in Figure 15In the example shown, examples of values of services that can be set in the service field include recording, rescue, platoon driving group formation, and merge point approach detection. Information set by the first UE on the sending side of the discovery message when each of these services is stored in the service field will be described below. In addition, the conditions for the second UE on the receiving side to respond to the message, the processing to be performed together with the response, and the information set in the response message will be described. Note that the service content is not limited to the above four services, and values representing services other than these can also be set in the service field. For example, the above four services are services in the case where the UE is installed on a vehicle, and services in the case where the UE is not installed on a vehicle can be defined. In addition, the information stored in the discovery message, the response conditions in the UE on the receiving side, the processing to be performed, and the information included in the response message are not limited to Figure 15 the example shown. That is, for example, even if the service is "recording", the content is different from Figure 15 the content shown and described later.

[0100] First, the case of setting "recording" in the service field will be described. In this case, the first UE on the sending side of the discovery message stores the location information of its own device (the first UE) in the discovery message. Then, for example, if all of the following four conditions are satisfied, the second UE on the receiving side of the message returns a response message to the first UE. The first condition is that the second UE is performing image capture using the image capture function of its own device (the second UE) when it receives the discovery message. This is a condition for capturing a phenomenon such as a traffic accident. That is, in the case where the discovery message is sent after such a phenomenon occurs, if the second UE is not performing image capture at this time, it is assumed that the second UE has not captured the desired recorded video. Therefore, if the second UE is not performing image capture when it receives the discovery message, it does not send a response message to the first UE. The second condition is that the second UE is present in an area where the distance from the first UE falls within a predetermined range. The communicable distance of sidelink communication between UEs is, for example, about 500 meters. Therefore, the predetermined range can be set to be equal to or less than the communicable distance. For example, in a case of a similar recording service, an image captured by the second UE present at a distance close to the side (the location where the first UE is present) is useful for specifying the situation. Therefore, if the second UE is far from the first UE and is thus estimated to be unable to perform useful image capture, the second UE does not send a response message to the first UE. The above-mentioned predetermined range can be set to obtain such useful images. Note that the predetermined range can be a fixed value or a dynamically settable value. The third condition is that its own device (the second UE) is in a posture where it can capture the position of the UE (the first UE) that has sent the discovery message through the image capture function of its own device. That is, for example, if the second UE is in a posture where it cannot capture a recording target such as an accident scene, even if the distance from the first UE is close enough, the second UE does not send a response message to the first UE. The fourth condition is that the second UE allows the recorded video to be provided to a third party. Since a recorded video such as a captured image by a dashcam belongs to the image capturer, the video cannot be given to a third party without the permission of the owner. Therefore, if the second UE does not allow the recorded video to be provided to a third party, it does not send a response message to the first UE. The second UE that satisfies the above first to fourth conditions can send a response message to the first UE.

[0101] If the second UE decides to send a response message, it stores the video captured by the image capture function of its own device (at least does not discard the video within a predetermined time period). In addition, the second UE sends a response message to the first UE, and the response message includes identification information for sidelink communication, such as the International Mobile Equipment Identity (IMEI). After that, by setting the IMEI as the destination, the first UE can thus request the communication device that has recorded the video to send the video.

[0102] Next, the case of setting "rescue" in the service field will be described. In this case, the first UE stores the location information of its own device and the rescue target requested by its own device in the discovery message and sends the discovery message. For example, information indicating the need for rescue (such as "failure", "out of gasoline", "in distress", or "tailgating vehicle approaching") is stored in the discovery message as information on the rescue target. In the example, the "failure" information may be information indicating a more detailed rescue target (such as "engine failure" or "flat tire"). The second UE sends a response message to the discovery message on the condition that its own device can go for rescue or its own device can perform communication via the core network when receiving the discovery message. Note that if the second UE sends a response message because its own device can go for rescue, it goes to the location of the first UE without performing any processing in the device. Note that in this case, the second UE may send a response message including information on the estimated time when its own device will reach the location of the first UE. On the other hand, if the second UE sends a response message because its own device can perform communication via the core network, it performs relay communication with another rescuer via the core network. In this case, the second UE may transmit the response message generated by another rescuer to the first UE without sending the response message generated by its own device. This response message may include information on the estimated time when another rescuer will reach the location of the first UE.

[0103] Subsequently, the case of setting "platoon formation" in the service field will be described. In this case, a group name serving as an identifier for forming a platoon is set in the discovery message. The second UE can decide whether to send a response message by a manual operation of the user. If the second UE sends a response message, it sends a response message to the first UE including the identifier of its own device and the password for joining the group. The second UE may use, for example, the nickname of its own device as the identifier. The first UE can obtain the password and identifier associated with the second UE by receiving the response message and determine whether to allow the second UE to join the group. Multiple vehicles including the UE belonging to the group thus formed can be controlled to perform automatic platoon driving using, for example, known autonomous driving technology.

[0104] Finally, the case of setting "merging point approach detection" in the service field will be described. In this case, the discovery message includes the location information of the first UE and the information indicating the traveling direction. If the distance to the first UE falls within a predetermined range and the second UE travels in the direction in which it will approach the first UE at the merging point, then the second UE sends a response message. In the example, the second UE does not perform any processing other than sending the response message. The second UE sends a response message to the first UE, and the response message includes the location information of its own device (the second UE) and the information indicating the traveling direction. Therefore, the first UE can detect that it approaches the second UE at the merging point in the forward direction of its own device.

[0105] Figure 16 An example of the process of the processing performed by the second UE on the receiving side of the discovery message according to this embodiment is shown. When receiving a discovery message sent from another UE (step S1601), the second UE confirms the service included in the discovery message (step S1602). If "recording" is set in the service field of the discovery message (step S1603), then the second UE performs the processing associated with "recording" (step S1604). On the other hand, if "rescue" is set in the service field of the discovery message (step S1605), then the second UE performs the processing associated with "rescue" (step S1606). Alternatively, if "formation driving group formation" is set in the service field of the discovery message (step S1607), then the second UE performs the processing associated with "formation driving group formation" (step S1608). If "merging point approach detection" is set in the service field of the discovery message (step S1609), then the second UE performs the processing associated with "merging point approach detection" (step S1610). Note that the processing associated with each service is as described above, so the repeated description will be omitted.

[0106] Reference will be made to Figure 17Describe the use cases of the system. In this example, vehicle 1701, vehicle 1702, network camera 1703, vehicle 1704, vehicle 1705, and roadside unit (RSU 1706) are within a predetermined range. Consider the following scenario: Vehicles 1701 and 1702 collide, and the UE mounted on vehicle 1701 requests other UEs in the vicinity to provide captured images. In this case, the UE mounted on vehicle 1701 sends a discovery message. Hereinafter, this UE will be simply referred to as "vehicle 1701". Similarly, vehicle 1702, network camera 1703, vehicle 1704, vehicle 1705, and RSU 1706 respectively indicate the UEs in these devices. Vehicle 1701 sets "record" in the service field of the discovery message and sets the location information of vehicle 1701 as the information corresponding to the service in the frame payload field. Note that vehicle 1702 also performs the above processing, which is the same as that performed by vehicle 1701. Therefore, only vehicle 1701 will be described and the description of vehicle 1702 will be omitted.

[0107] Assume that vehicle 1702 has an image capture function and can only capture videos in the traveling direction, but is not allowed to provide recorded videos. Note that in Figure 17 the arrow indicates the image capture direction. Assume that network camera 1703 has an image capture function, can capture videos in all directions (at least the entire area within the lane where vehicle 1701 etc. travel), and is allowed to provide recorded videos. Assume that vehicle 1704 has an image capture function, can capture videos in the traveling direction and the opposite direction, and is allowed to provide recorded videos. Assume that vehicle 1705 has an image capture function, can only capture videos in the traveling direction, and is allowed to provide recorded videos. Assume that RSU 1706 does not have an image capture function.

[0108] For example, assume that vehicle 1701 can perform sidelink communication with vehicle 1702, network camera 1703, vehicle 1704, vehicle 1705, and RUS1706. That is, the communicable range of vehicle 1701 includes the location of RSU1706. On the other hand, vehicle 1701 can set a range different from the communicable range (such as the shaded area shown in Figure 17 as the range for vehicle 1701 to search for other UEs using the discovery message. Figure 17 Shows the case where vehicle 1701 sets the range including the locations where vehicle 1702, network camera 1703, vehicle 1704, and vehicle 1705 are respectively located but not including the location of RUS 1706 as the search range.

[0109] Figure 18 Shows an example of the operations performed in the system in the case shown in Figure 17 Note that Figure 18An operation example is shown in the case where vehicle 1701 sends a discovery message for requesting a "recording" service from other UEs in the vicinity by using a collision with vehicle 1702 as a trigger.

[0110] First, after detecting an impact of a predetermined level or higher (F1801), vehicle 1701 generates a discovery message by setting "recording" in the service field and storing the location information of its own device in the frame payload field, and sends the discovery message to the vicinity (F1802). Note that the location information of vehicle 1701 can be obtained by using, for example, the GPS function installed on vehicle 1701. Each of vehicle 1702, network camera 1703, vehicle 1704, vehicle 1705, and RSU 1706 receives the discovery message and designates that "recording" is set in the service field. Then, each of vehicle 1702, network camera 1703, vehicle 1704, vehicle 1705, and RSU 1706 decides whether to send a response message to the discovery message.

[0111] Vehicle 1702 performs image capture in its own device but does not allow video to be provided. Therefore, vehicle 1702 decides not to send a response message (F1803) and directly ends the process.

[0112] Since network camera 1703 is performing image capture in the direction of vehicle 1701, the distance from vehicle 1701 falls within a predetermined range, and video can be provided, it decides to return a response message (F1804). In this case, network camera 1703 stores the captured video (F1805) and returns a response message including the IMEI of its own device to vehicle 1701 (F1806). Then, vehicle 1701 subsequently stores the IMEI of network camera 1703 in order to obtain video from network camera 1703 (F1807). Similarly, vehicle 1704 also decides to return a response message (F1808), stores the captured video (F1809), and returns a response message including the IMEI of its own device to vehicle 1701 (F1810). Then, vehicle 1701 stores the IMEI of vehicle 1704 (F1811).

[0113] Vehicle 1705 is performing image capture in its own device, video can be provided, and the distance from vehicle 1701 falls within a predetermined range, but it is not performing image capture in the direction of vehicle 1701. Therefore, vehicle 1705 decides not to send a response message (F1812) and directly ends the process.

[0114] RSU 1706 does not have a capture function, and the distance from vehicle 1701 exceeds the predetermined range. Therefore, RSU 1706 decides not to send a response message (F1813) and directly ends the process.

[0115] Thereafter, the vehicle 1701 sets the IMEI of the network camera 1703 stored in F1807 as the destination and requests the network camera 1703 to send the stored video (F1814). When receiving the request message from the vehicle 1701, the network camera 1703 sends the video stored in F1805 to the vehicle 1701 (F1815). When receiving the video from the network camera 1703, the vehicle 1701 stores the video (F1816). In addition, the vehicle 1701 sets the IMEI of the vehicle 1704 stored in F1811 as the destination and requests the vehicle 1704 to send the stored video (F1817). When receiving the request message from the vehicle 1701, the vehicle 1704 sends the video stored in F1809 to the vehicle 1701 (F1818). When receiving the video from the vehicle 1704, the vehicle 1701 stores the video (F1819).

[0116] Subsequently, reference will be made to Figure 19 an example of the process of processing performed by a UE on the request side of the "recording" service (such as the UE installed on the vehicle 1701) will be described. Note that hereinafter, the UE on the request side of the "recording" service is sometimes referred to as the first UE, and the UE on the request receiving side of the "recording" service is sometimes referred to as the second UE.

[0117] First, the first UE monitors whether an impact (collision) of a predetermined level or higher has occurred (step S1901). Note that this monitoring operation is performed to determine the transmission trigger of the discovery message for requesting the service. If another trigger is used, then state monitoring corresponding to the trigger, etc. can be performed. For example, if the discovery message is sent when a predetermined user operation is accepted, then the first UE can monitor whether the predetermined user operation is accepted. For example, when there is another vehicle driving dangerously around the vehicle 1701, if a user operation for requesting the surrounding vehicle to perform recording is executed, then the discovery message can be sent. When detecting the transmission trigger of the discovery message (in this example, a collision) ( "Yes" in step S1901), the first UE generates a discovery message in which the requested service (in this example, "recording") is set and broadcasts the discovery message (step S1902). Then, the first UE waits for the reception of a response message from another UE in the vicinity (step S1903). Note that the first UE can, for example, send the discovery message multiple times in each predetermined cycle, or if a response message is not received within a predetermined time period, then the discovery message can be retransmitted. Alternatively, if a response message is not received within a predetermined time period, then the first UE can end the process.

[0118] When receiving a response message (Yes in step S1903), the first UE obtains and stores the IMEI of the second UE included in the response message as the source of the response message (step S1904). Thereafter, the first UE sets the stored IMEI as the destination to request the second UE to provide the stored video (step S1905), and obtains the video from the second UE (step S1906).

[0119] Next, reference will be made to Figure 20 an example of a process of processing performed by a UE on the request receiving side of the "recording" service (such as UEs respectively installed on vehicle 1702, network camera 1703, vehicle 1704, vehicle 1705, and RSU 1706). In this example, hereinafter, the UE on the request side of the "recording" service will sometimes also be referred to as the first UE, and the UE on the request receiving side of the "recording" service will sometimes be referred to as the second UE. Note that the first UE performing the Figure 19 processing shown in Figure 20 can of course perform the Figure 20 processing shown in parallel. Similarly, the second UE performing the Figure 19 processing shown in can also perform the

[0120] processing shown in parallel. That is, a UE can be used as one of the first UE and the second UE according to the status of its own device. When receiving a discovery message from the first UE (Yes in step S2001), the second UE determines whether to respond to the discovery message (step S2002). That is, for example, the second UE determines whether the conditions referred to in Figure 15Conditions for responding to discovery messages as described. If it is determined that the conditions are not met ("No" in step S2002), then the second UE directly ends the process without sending a response message. For example, as described above, since each of vehicle 1702, vehicle 1705, and RSU 1706 does not meet the conditions, no response message is sent. On the other hand, if it is determined that the conditions are met ("Yes" in step S2002), then the second UE stores the video (step S2003), generates a response message including the IMEI of its own device, and sends the response message to the first UE (step S2004). For example, as described above, since each of network camera 1703 and vehicle 1704 meets the conditions, it stores the video and sends a response message. If the second UE receives a video acquisition request with the IMEI of its own device set as the destination from the first UE after sending the response message ("Yes" in step S2005), then the second UE sends the video stored in step S2003 to the first UE (step S2006). Note that, for example, if the second UE does not receive a video acquisition request within a predetermined time period ("No" in step S2005), then the second UE may delete the video stored in step S2003 and end the process.

[0121] As described above, by using sidelink communication, vehicle 1701 can request another UE in its vicinity to store and provide a video in response to the detection of, for example, a collision, and acquire the stored video.

[0122] Note that the above operation example is associated with "recording". However, for example, Figure 16 the processing in steps S1606, S1608, and S1610 is based on Figure 15Performed by the table shown in [Fig. 0]. For example, in addition to or instead of the above "Record", vehicle 1701 may send a discovery message with "Rescue" set. In this case, for example, vehicle 1705 is traveling in a direction away from vehicle 1701 and thus cannot go for rescue. Therefore, for example, if vehicle 1705 cannot perform communication via the core network, it can be blocked from sending a response message. Neither the network camera 1703 nor the RSU 1706 can perform rescue, but will relay the discovery message to another rescuer if it can perform communication via the core network. In the example, each of the network camera 1703 and the RSU 1706 can send the discovery message to a contact such as the police. Then, each of the network camera 1703 and the RSU 1706 can transmit the response message from another rescuer to vehicle 1701. In this case, in the response message, the estimated arrival time of another rescuer can be set. Since vehicle 1704 is traveling in a direction approaching vehicle 1701, it can go for rescue. Therefore, for example, vehicle 1704 can send a response message in which the estimated arrival time is set based on the distance from vehicle 1701. Note that since vehicle 1702 is a party involved in the collision, it cannot go for rescue and thus does not send a response message.

[0123] If a discovery message with "Platoon formation group formation" set is sent, the vehicle that receives the discovery message notifies the driver that the message has been received. If the vehicle receives approval from the driver to form a platoon formation group, it can notify the vehicle that is the source of the discovery message of the response message. Alternatively, if a discovery message with "Merge point approach detection" set is sent, another vehicle approaching the merge point sends a response message including the position information and traveling direction of its own device.

[0124] As described above, by using the sidelink discovery message and the response message thereto, services requested by the UE on the sending side of the discovery message can be appropriately provided to the UE.

[0125] [Third Embodiment]

[0126] The above First Embodiment and Second Embodiment can be combined. For example, as Figure 21 shown, a discovery message 2101 can be formed. This discovery message 2101 is obtained by adding a "Service" field described with reference Figure 4 immediately after the "Connection capability information" in the discovery message shown in [Fig. 16]. Note that the order of these fields is not limited to this, and fields such as the connection capability field can be arranged after the service field. In addition, the information corresponding to the service field is stored in the Figure 14 frame payload field shown in [Fig. 18]. Figure 4 shown in [Fig. 20].

[0127] By using this structure, for example, the first UE on the sending side of the discovery message can perform D2D communication and specify a second UE that can perform a "service". For example, in Figure 17 , in response to detecting an impact of a predetermined level or higher, the vehicle 1701 searches for another UE that can perform D2D communication as in the first embodiment and searches for another UE that supports the "recording" service as in the second embodiment. That is, the vehicle 1701 sends a discovery message in which the bit corresponding to D2D communication in the connection capability field is set to 1 and "recording" is set in the service field. In addition, the vehicle 1701 sets information corresponding to the service (in this case, location information) in the frame payload field. When receiving the discovery message, if another UE in the vicinity supports D2D communication and satisfies the conditions associated with the "recording" service, it sends a response message. For example, if Figure 17 the vehicle 1704 shown in does not support D2D communication, then even if the conditions associated with the recording service are satisfied, the vehicle 1704 may be blocked from sending a response message. In this way, the first UE can discover a second UE that can subsequently request and obtain a video through D2D communication. Note that if the vehicle 1702, the network camera 1703, the vehicle 1704, the vehicle 1705, and the RSU 1706 all satisfy D2D communication, then the same operations as those described in the second embodiment are performed.

[0128] Note that this is merely an example, and various forms are possible. For example, if a discovery message setting the "rescue" service is sent, then if network relay is also possible, a UE that satisfies the conditions for enabling communication via the core network may be made to send a response message. That is, a UE that can perform communication via the core network but cannot perform network relay may be blocked from sending a response message. On the other hand, even if a UE that can go for rescue cannot perform network relay, this UE may be made to send a response message. In this way, depending on the combination of the conditions satisfied and the sidelink communication method supported associated with the service, it can be decided whether to send a response message.

[0129] Unless otherwise specified, the above embodiments can be used in any combination.

[0130] The present invention can also be implemented by the following process: supplying a program for realizing at least one function of the above embodiments to a system or device via a network or a storage medium and reading and executing the program by at least one processor in a computer of the system or device. The present invention can also be implemented by a circuit (e.g., ASIC) for realizing at least one function.

[0131] The present invention is not limited to the above embodiments, and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, in order to enable the public to understand the scope of the present invention, the following claims are made.

[0132] This application claims the priority of Japanese Patent Application No. 2022-189531 filed on November 28, 2022, which is incorporated herein by reference.

Claims

1. A communication device, comprising: a communication unit configured to perform communication using a sidelink communication function in a cellular communication standard in the 3rd Generation Partnership Project (3GPP); and a search unit configured to search for another communication device after the device is connected for the sidelink communication function by sending a discovery message, the discovery message including information indicating a predetermined function to be performed using the sidelink communication function, and the other communication device being capable of performing the predetermined function.

2. The communication device according to claim 1, wherein the information indicating the predetermined function is information indicating a communication method supported by the communication device, and the search unit searches for the other communication device capable of performing the predetermined function based on a response sent by the other communication device when the other communication device that supports the communication method receives the discovery message.

3. The communication device according to claim 2, wherein the information indicating the communication method is information indicating a communication method that the communication device requests to be used for communicating with another communication device among a plurality of communication methods supported by the communication device.

4. The communication device according to claim 3, wherein the plurality of communication methods include a first communication method for performing direct communication between the communication device and the other communication device, a second communication method for relaying communication between the communication device and a communication partner of the communication device having a sidelink communication function, and a third communication method for relaying communication between the communication device and a base station.

5. The communication device according to any one of claims 1 to 4, wherein the information indicating the predetermined function includes information indicating a service requested by the communication device to be performed by another device, and the search unit searches for the other communication device capable of performing the predetermined function based on a response sent by the other communication device when the other communication device that satisfies a condition corresponding to the service receives the discovery message.

6. The communication device according to claim 5, wherein the communication device is a vehicle, and the information indicating the service includes at least one of a service for recording and providing information captured by the other device, a service for a rescue vehicle, a service for forming a platoon driving group with the vehicle, and a service for detecting a merging point where a vehicle approaches.

7. The communication device according to claim 6, wherein when the information indicating the service indicates a service for recording and providing information captured by the other device, the discovery message further includes location information of the communication device.

8. The communication device according to claim 7, wherein when the information indicating the service indicates a service for recording and providing information captured by the other device, the communication unit obtains an identification number of the other communication device from the response, and performs communication for obtaining information captured by the other communication device by using the identification number.

9. The communication device according to any one of claims 6 to 8, wherein when the information indicating the service indicates a service for a rescue vehicle, the discovery message further includes the location information of the communication device and the information indicating the requested rescue.

10. The communication device according to any one of claims 6 to 9, wherein when the information indicating the service indicates a service for a group for platooning with a vehicle, the discovery message further includes the information indicating the group name.

11. The communication device according to any one of claims 6 to 10, wherein when the information indicating the service indicates a service for detecting a merging point where a vehicle approaches, the discovery message further includes the location information of the vehicle and the information indicating the traveling direction.

12. The communication device according to claim 1, wherein the information indicating the predetermined function is information indicating the communication method requested to be used by the communication device and the service requested to be executed by another device by the communication device, and when the discovery message is received by another communication device that supports the communication method and satisfies the conditions corresponding to the service, the search unit searches for another communication device capable of executing the predetermined function based on the response sent by the other communication device.

13. A communication device, comprising: a communication unit configured to perform communication using a sidelink communication function in a cellular communication standard in the Third Generation Partnership Project (3GPP); and a sending unit configured to send a response to the other communication device when the communication device receives a discovery message sent by the other communication device for searching for a partner for sidelink communication, the response including information indicating a predetermined function to be executed after the devices are connected to perform the sidelink communication.

14. The communication device according to claim 13, wherein when the discovery message includes information indicating the predetermined function and the communication device supports the predetermined function, the sending unit sends a response including the information indicating the predetermined function to the other communication device.

15. The communication device according to claim 13 or 14, wherein the information indicating the predetermined function is information indicating a communication method supported by the communication device among a plurality of communication methods.

16. The communication device according to claim 15, wherein the plurality of communication methods include a first communication method for performing direct communication between the communication device and the other communication device, a second communication method for relaying communication between the other communication device and a communication partner of the communication device having a sidelink communication function, and a third communication method for relaying communication between the other communication device and a base station.

17. The communication device according to claim 16, wherein when the response includes information indicating the first communication method, the sending unit sends a response further including an identifier of a base station to which the communication device is currently connected or where the communication device is located.

18. The communication device according to claim 16 or 17, wherein, in the case where the response includes information indicating the second communication method, the sending unit sends a response that further includes an identifier of the communication partner.

19. The communication device according to any one of claims 16 to 18, wherein, in the case where the response includes information indicating the third communication method, the sending unit sends a response that further includes information of the base station.

20. The communication device according to claim 19, wherein the information of the base station includes at least one piece of information related to an identifier of the base station to which the communication device is currently connected, a usage frequency of the base station, a received radio field strength of a signal from the base station, and a communication carrier operating the base station.

21. The communication device according to claim 13, wherein the discovery message includes information indicating the predetermined function, the information indicating the predetermined function is information indicating a service requested by the other communication device to be executed by another device, and based on the fact that the communication device satisfies a condition corresponding to the service, the sending unit sends a response including the information indicating the predetermined function to the other communication device.

22. The communication device according to claim 21, wherein the other communication device is a vehicle, and the information indicating the service includes at least one of a service for recording and providing information captured by the other device, a service for a rescue vehicle, a service for forming a platoon driving group with the vehicle, and a service for detecting a merging point where the vehicle approaches.

23. The communication device according to claim 22, wherein, in the case where the information indicating the service indicates a service for recording and providing information captured by the other device, the sending unit sends the response to the other communication device by including an identifier of the communication device in the response based on the fact that the condition is satisfied.

24. The communication device according to claim 22 or 23, wherein, in the case where the information indicating the service indicates a service for a rescue vehicle, the sending unit sends the response to the other communication device by including information on an estimated time when the communication device will reach the position of the vehicle in the response based on the fact that the condition is satisfied.

25. The communication device according to any one of claims 22 to 24, wherein, in the case where the information indicating the service indicates a service for forming a platoon driving group with the vehicle, the sending unit sends the response to the other communication device by including an identifier and a password of the communication device for joining the group in the response based on the fact that the condition is satisfied.

26. The communication device according to any one of claims 22 to 25, wherein the communication device is a vehicle, and In a case where information indicating the service indicates a service for detecting a merging point where a vehicle approaches, the transmitting unit transmits the response to the other communication device by including position information of the communication device and information indicating a traveling direction in the response based on the fact that the condition is satisfied.

27. A control method performed by a communication device that communicates using a sidelink communication function in a cellular communication standard in the Third Generation Partnership Project (3GPP), the control method including: Searching for another communication device after the device is connected for the sidelink communication function by transmitting a discovery message, the discovery message including information indicating a predetermined function performed using the sidelink communication function, the other communication device being capable of performing the predetermined function.

28. A control method performed by a communication device that communicates using a sidelink communication function in a cellular communication standard in the Third Generation Partnership Project (3GPP), the control method including: In a case where the communication device receives a discovery message transmitted by the other communication device for searching for a partner for sidelink communication, transmitting a response to the other communication device, the response including information indicating a predetermined function performed after the device is connected to perform the sidelink communication.

29. A program for causing a computer to function as each unit of the communication device defined in any one of claims 1 to 26.

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