Communication device, method for controlling communication device, and program

Abstract

The communication apparatus capable of performing sidelink communication includes: a detection unit configured to detect at least one different communication apparatus capable of serving as a synchronization source and capable of performing sidelink communication; an acquisition unit configured to acquire predetermined information from each of the at least one different communication device detected by the detection unit; and a first setting unit, the first setting unit is configured to set a synchronization priority in a case where a predetermined operation setting with respect to the synchronization priority has been performed, and the first setting unit determines, based on the predetermined information acquired by the acquisition unit, that there is a different communication device from which information has been acquired among the at least one different communication device. The different communication device from which the information has been acquired is set as a time synchronization source, the information indicating that the different communication device is a predetermined type of communication device to be used as a synchronization source.

Description

Technical Field

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

[0002] In a terminal-to-terminal direct communication method called PC5 communication or sidelink communication in the 3GPP standard, synchronization is achieved using a signal from a terminal that is synchronized with absolute time as accurately as possible to achieve synchronization of transmission / reception timing between terminals. PC5 communication terminals utilize, for example, a public wireless base station or a global navigation satellite system (GNSS) (Patent Document 1). 3GPP (registered trademark) stands for Third Generation Partnership Project.

[0003] Citation List

[0004] Patent Literature

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-525894 Summary of the invention

[0006] Technical issues

[0007] In a PC5 network (side link communication network) including fixed user equipment and movable user equipment, the PC5 communication terminal (user equipment) with the highest signal strength is selected as the synchronization source based on the assumption that it is not synchronized with a public wireless base station or GNSS. However, in the case where only user equipment with high signal strength is used as the synchronization source, the signal strength changes depending on the relative position relationship with the device, which leads to frequent changes in the synchronization source equipment. The frequent changes in the synchronization source equipment make it difficult to achieve stable synchronization in the entire network.

[0008] In view of the above-mentioned problems, the present invention is directed to providing a communication apparatus capable of achieving stable synchronization in a network adopting a side link communication method.

[0009] Solution to the problem

[0010] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a communication device capable of performing side link communication includes: a detection unit, which is configured to detect at least one different communication device that can be used as a synchronization source and can perform side link communication; an acquisition unit, which is configured to acquire predetermined information from each of the at least one different communication device detected by the detection unit; and a first setting unit, which is configured to set the different communication device from which the information has been acquired as a time synchronization source in a case where the information acquired by the acquisition unit indicates that the different communication device is a communication device of a predetermined type to be used as a synchronization source.

[0011] Advantageous Effects of the Invention

[0012] According to the present invention, stable synchronization can be achieved in a network adopting the side link communication method. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a block diagram illustrating a communication device according to a first exemplary embodiment of the present invention.

[0014] Figure 2 yes Figure 1 Functional block diagram of the communication device shown in .

[0015] Figure 3 The diagram includes Figure 1 FIG. 4 is a diagram of a network of communication devices shown in FIG.

[0016] Figure 4 This is a functional block diagram in the case where the communication device is a communication device installed in a fixed manner.

[0017] Figure 5 is a diagram illustrating an example of an information element indicating a type of a communication device.

[0018] Figure 6 It is a flowchart executed by the communication device in the first exemplary embodiment.

[0019] Figure 7 is a diagram illustrating an example of an information element indicating a priority synchronization destination.

[0020] Figure 8 It is a flowchart executed by the communication device in the second exemplary embodiment. DETAILED DESCRIPTION

[0021] The mode for implementing the present invention will be described in detail below with reference to the accompanying drawings. Note that the exemplary embodiments described below are merely examples of means for implementing the present invention, and should be appropriately modified or changed depending on the configuration and various conditions of the device to which the present invention is applied, and the present invention is not limited to the exemplary embodiments described below.

[0022] First Exemplary Embodiment

[0023] Figure 1 1 is a block diagram illustrating an example of a configuration of a communication device 101 according to an exemplary embodiment of the present invention.

[0024] The communication device 101 includes a control unit 102, a storage unit 103, a wireless receiving unit 104, a wireless transmitting unit 105, a display unit 106, and an input unit 107. The communication device 101 is a communication device capable of performing communication using a terminal-to-terminal direct communication method called PC5 communication or side link communication in the third generation partnership project (3GPP) standard. Note that the communication device 101 may be referred to as a communication terminal device or terminal hereinafter.

[0025] The control unit 102 executes the control program stored in the storage unit 103 to control the entire communication device 101. The control unit 102 is composed of one or more CPUs or one or more MPUs. The control unit 102 can execute an operating system (OS), a driver, an application, etc. CPU stands for central processing unit. MPU stands for microprocessing unit. The control unit 102 includes a built-in clock. Note that the control unit 102 may include a graphics processing unit (GPU).

[0026] The storage unit 103 stores a control program to be executed by the control unit 102. In addition, the storage unit 103 stores various information such as communication parameters and captured image data. Various operations to be described below are performed by the control unit 102 executing the control program stored in the storage unit 103.

[0027] The storage unit 103 includes, for example, a ROM storing a control program, a RAM used as a work area to be used when the control unit 102 executes a program read out from the ROM, etc. Communication parameters and captured image data (image file) are stored in the RAM.

[0028] ROM stands for Read Only Memory. RAM stands for Random Access Memory.

[0029] The wireless receiving unit 104 receives PC5 signals and GNSS signals in the 3GPP standard.

[0030] The wireless transmission unit 105 transmits a PC5 signal in the 3GPP standard.

[0031] The display unit 106 displays characters, images, etc. The display unit 106 includes an LCD or an LED, and outputs visually recognizable information (visual information). It is noted that the display unit 106 may include a speaker, etc., and outputs auditorily recognizable information (sound information). LCD stands for liquid crystal display. LED stands for light emitting diode. The display unit 106 may include, for example, a screen touch sensor that enables user operation of applications via a GUI. GUI stands for graphical user interface.

[0032] The input unit 107 is used when the user performs various inputs and the like on the communication apparatus 101. The input unit 107 includes, for example, a mouse and a keyboard, or a touch panel, etc., all not shown, and acquires (accepts) the user's input via these devices.

[0033] Note that the communication device 101 may include a distance sensor (not shown) that measures the distance to another communication device.

[0034] Figure 2 is a block diagram illustrating an example of a software functional configuration 201 of the communication device 101 .

[0035] The software function configuration 201 includes a signal receiving unit 202, a signal sending unit 203, a data storage unit 204, a display control unit 205, and a scanning control unit 206. In addition, the software function configuration 201 includes a synchronization achievable / impossible determination unit 207, a detection unit 208, a synchronization processing unit 209, a priority synchronization source type setting unit 210, and a priority synchronization source type checking unit 211.

[0036] The signal receiving unit 202 performs reception of a PC5 signal and a GNSS signal. The signal receiving unit 202 acquires notification information to be described below. The signal transmitting unit 203 performs transmission of a PC5 signal. The data storage unit 204 stores and retains software and information such as authentication information.

[0037] The display control unit 205 performs control processing of a screen to be displayed on the display unit 106 .

[0038] The scan control unit 206 performs scanning (detection) as to whether or not a synchronization reference device (different communication apparatus that can be used as a synchronization source) for achieving synchronization in the physical layer of the PC5 signal exists around.

[0039] The synchronization achievable / unachievable determining unit 207 determines whether synchronization is achievable with one or more (at least one) synchronization reference devices that can be obtained from the result of the scanning by the scanning control unit 206 .

[0040] The detection unit 208 detects a fixed communication device to be described below and a different synchronization reference device among synchronization reference devices detected (discovered) by the scanning of the scanning control unit 206. The fixed communication device is a communication device (terminal) installed in a fixed and immovable manner.

[0041] The synchronization processing unit 209 determines whether synchronization is to be achieved with a fixed communication device to be described below or with a different device based on a result of determination by the synchronization achievable / impossible determination unit 207 or a result of detection by the detection unit 208 .

[0042] The priority synchronization source type setting unit 210 sets the type of synchronization source that should be preferentially referenced among the types of synchronization reference devices. The priority synchronization source type setting unit 210 sets sl-SyncPriority indicating the priority synchronization source of the communication apparatus 101, for example.

[0043] The priority synchronization source type check unit 211 checks an information element indicating the type of a synchronization source that should be preferentially referenced in order to achieve synchronization in the physical layer.

[0044] Figure 2 Each functional component shown in can be realized by executing a predetermined processing program by the control unit 102 (for example, CPU) of the communication device 101. Note that, Figure 2 Some of the functional components 202 to 211 in may be collectively implemented as one functional component. Alternatively, one functional component may be divided into a plurality of functional components. In addition, Figure 2 At least a portion of the functional components in the can be implemented using dedicated hardware. In the case where the functional components are implemented using hardware, for example, it is only necessary to automatically generate a dedicated circuit on the FPGA from a program for implementing each process using a predetermined compiler. FPGA stands for Field Programmable Gate Array. Alternatively, each functional component can be implemented as hardware by forming a gate array circuit similar to an FPGA. Also alternatively, each functional component can be implemented using an application specific integrated circuit (ASIC). In this case, the hardware operates based on the control of the control unit 102.

[0045] Figure 3 is a diagram illustrating a network 300 including the above-mentioned five communication devices 101. In the network 300 according to the present exemplary embodiment, the communication devices 101 are fixed user equipment 301 and fixed user equipment 302 when installed in a fixed manner, and are movable user equipment 303, movable user equipment 304, and movable user equipment 305 when used as movable devices. The fixed user equipment 301 and the fixed user equipment 302 may be referred to as fixed terminals. Each of the movable user equipment 303, the movable user equipment 304, and the movable user equipment 305 is, for example, an autonomous vehicle traveling within a factory. The user equipment is hereinafter referred to as a UE.

[0046] like Figure 4 As shown in Figure 2 In addition to the configuration in FIG. 1 , each of the fixed UE 301 and the fixed UE 302 further includes a fixed terminal information notification unit 401. The fixed terminal information notification unit 401 gives (sends) a notification indicating that the fixed UE 301 and the fixed UE 302 are each a fixed terminal. Specifically, as Figure 5As shown in , the fixed terminal information notification unit 401 gives a notification including the FixedUE information indicating the UE type in the information element (IE) to be notified by the fixed UE, which enables the different communication devices 101 to detect the fixed UE. The notification is performed using a beacon signal. The notification information sent from one UE is received and acquired by the wireless receiving unit 104 (signal receiving unit 202) of the different UE.

[0047] Figure 6 1 is a flowchart for executing a process of determining whether or not the movable UE 303 as the communication device 101 according to the present exemplary embodiment is to be synchronized with the fixed UE 301. Figure 6 The flowchart in is initiated by the control unit 102 of the mobile UE 303, for example, when the network 300 is established or the mobile UE 303 participates in the network 300. Alternatively, Figure 6 The flowchart in FIG. 3 may be initiated by the control unit 102 of the mobile UE 303 when the mobile UE 303 detects that a new communication device has joined the network 300 . Figure 6 The flowchart in FIG. 1 is realized by the control unit 102 of the mobile UE 303 reading out and executing a computer program stored in the storage unit 103. In the figure, S is an abbreviation of Step.

[0048] when Figure 6 When the process in starts, the mobile UE 303 starts operating with the built-in clock of the mobile UE 303 (S601).

[0049] In S602 after S601, under the control of the scanning control unit 206, the mobile UE 303 performs scanning as to whether there is a synchronization reference device (a different communication device that can be used as a synchronization source) in the surroundings for realizing synchronization in the physical layer of the PC5 signal. In this exemplary embodiment, it is assumed that the mobile UE 303 detects the fixed UE 301 and the mobile UE 304 as synchronization reference devices. That is, the scanning control unit 206 detects different communication devices (fixed UE 301 and mobile UE 304) that can be used as synchronization sources within a predetermined range from the mobile UE 303.

[0050] In S603 following S602, the mobile UE 303 uses the priority synchronization source type checking unit 211 to determine whether sl-SyncPriority indicating the priority synchronization source of the mobile UE 303 is Fixed UE indicating a fixed UE.

[0051] In a case where the result of the determination in S603 is "Yes", the movable UE 303 uses the detection unit 208 to determine whether it has detected the fixed UE 301 (S604).

[0052] In a case where the result of the determination in S604 is "Yes", the movable UE 303 uses the synchronization processing unit 209 to operate in synchronization with the fixed UE 301 (S605).

[0053] In the case where the result of the determination in S604 is "No", the mobile UE 303 performs a known synchronization process. That is, the mobile UE 303 performs the synchronization process described in §5.8.6.2 "Selection and reselection of synchronisation reference" in 3GPP TS 38.331 V16.7.0 (S606). Specifically, the mobile UE 303 and Figure 3 Synchronize with devices not shown in the figure (e.g., public wireless base stations).

[0054] By performing the above-mentioned processing, in the case where the mobile UE 303 has a setting for synchronizing with the fixed UE with priority (S603: Yes) and in the case where the mobile UE 303 detects the fixed UE 301 (S604: Yes), the mobile UE 303 can be synchronized with the fixed UE 301. In this way, in the case where the mobile UE 303 has a setting regarding a different communication device that should be preferentially referenced (S603: Yes), the fixed UE 301 is preferentially set as a time synchronization source compared with the public wireless base station and the satellite positioning system.

[0055] In contrast, in a case where the result of the determination in S603 is "No", the mobile UE 303 uses the priority synchronization source type checking unit 211 to determine whether sl-SyncPriority indicating the priority synchronization source of the mobile UE 303 is not set (S607).

[0056] In the case where the result of the determination in S607 is "No", the process proceeds to S611, and the movable UE 303 performs a known synchronization process. The synchronization process in S611 is the same as the synchronization process in S606.

[0057] In a case where the result of the determination in S607 is "Yes", the mobile UE 303 uses the detection unit 208 to determine whether it has detected gnss or gnbEnb (S608).

[0058] In a case where the result of the determination in S608 is “Yes”, the process proceeds to S606 .

[0059] In a case where the result of the determination in S608 is "No", the movable UE 303 uses the detection unit 208 to determine whether it has detected the fixed UE 301 (S609).

[0060] In a case where the result of the determination in S609 is "Yes" (eg, the mobile UE 303 has detected the fixed UE 301), the mobile UE 303 uses the synchronization processing unit 209 to operate in synchronization with the fixed UE 301 (S610).

[0061] In a case where the result of the determination in S609 is “NO”, the process proceeds to S611 .

[0062] With the above-mentioned process, in the case where the mobile UE 303 has detected the fixed UE 301 in the network 300, the mobile UE 303 can be stably connected to the fixed UE 301, which enables the mobile UE 303 to achieve stable synchronization in the physical layer.

[0063] That is, according to the present exemplary embodiment, in the case where the information acquired from the fixed UE 301 is information indicating that the different communication device is a predetermined type of communication device to be used as a synchronization source, the fixed UE 301 as the different communication device from which the information has been acquired is set as the time synchronization source. As a result, the mobile UE can achieve stable synchronization.

[0064] Note that, in network 300 allowing PC5 to communicate, if the UE used as a synchronization reference changes to, for example, mobile UE 304 as the signal strength changes based on the relative positional relationship between mobile UE 303 and fixed UE 301, it is difficult for mobile UE 303 to achieve stable synchronization in the physical layer. According to the present exemplary embodiment, fixed UE 301 is used as a synchronization reference, which enables mobile UE 303 to achieve stable synchronization.

[0065] Note that, Figure 6 The sl-SyncPriority described in S603 and S607 in FIG. 1 is an internal parameter of the mobile UE 303. The internal parameter (setting content) may be pre-set in the communication device 101, or may be set using the input unit 107. In addition, the internal parameter may be set with reference to the content of the sl-SyncPriority in the IE notified by different UEs, such as Figure 7 as shown in .

[0066] In addition, it has been given in Figure 6In S602 of the description, the scanning control unit 206 detects different communication devices (fixed UE 301 and movable UE 304) that can be used as synchronization sources within a predetermined range from the movable UE 303, but the UEs detected as different communication devices that can be used as synchronization sources are not limited to UE 301 and UE 304. For example, the UEs detected in S602 may be fixed UE 301, fixed UE 302, movable UE 304, and movable UE 305. In this case, since two fixed UEs, i.e., fixed UE 301 and fixed UE 302, are detected in S604, a step of selecting one fixed UE (e.g., UE 301) is provided between S604 and S605. In the case where there are multiple fixed UEs and one fixed UE is selected as the synchronization destination, for example, among the UEs having a side link synchronization signal ID (SLSSID) with a value between 0 and 337, the UE with the smallest value is selected. It is assumed that the SLSSID conforms to the SLSSID described in §6.3.5 "Sidelinkinformation elements" in 3GPP TS 38.331 V16.7.0. SLSSID stands for Sidelink Synchronization Signal ID. SLSS consists of two synchronization signals, a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS). In the case where the sidelink synchronization signal is transmitted based on the synchronization timing of the base station device, a sidelink synchronization signal of SLSSID from 0 to 167 is used. In addition, in the case where the sidelink synchronization signal is not based on the synchronization timing of the base station device, a sidelink synchronization signal of SLSSID from 168 to 335 is used.

[0067] The information indicating the fixed UE in the above-mentioned exemplary embodiment is information indicating that the UE is immobile, but it can be said to be information indicating that the UE can be stably used as a synchronization source in the area due to its immobility. Instead of this information, it is possible to adopt a configuration in which the UE that wants to be used as a synchronization source notifies its surroundings of information indicating whether it wants to be used as a synchronization source. In this case, for example, a business operator who establishes a PC5 network only needs to set information indicating that it is desired to use the immobile UE as a synchronization source in the fixed UE when installing the fixed UE. Alternatively, for example, it is also possible to adopt a configuration in which the information indicating the desire to be used as a synchronization source or the information indicating the fixed UE is set as a factory default setting when manufacturing a fixed PC5 device including a pedestal and a fixing jig.

[0068] The network 300 mentioned above is configured to include five pieces of UE, but the number of UEs constituting the network 300 is not limited to five. For example, there may be three or more fixed UEs. In the case where there are three or more fixed UEs, the number of UEs that should be used as time synchronization sources may be three or more. That is, in the case of obtaining multiple pieces of information each indicating that different communication devices are communication devices of a predetermined type to be used as synchronization sources, for example, a step of selecting a fixed UE is provided between S604 and S605 as described above. Then, a UE with a minimum SLSSID is selected from the multiple pieces of fixed UEs obtained. Alternatively, it is also possible to adopt a configuration in which, in the case of starting the operation of PC5 communication, the fixed UE pre-collects (pre-acquires) the SLSSIDs sent from the surrounding UEs and sets its own SLSSID to a configuration that does not conflict with other UEs. Also alternatively, it is also possible to adopt a configuration in which, in the case of multiple pieces of fixed UEs with a minimum SLSSID, control is performed to perform negotiation between fixed UEs and change the SLSSID of any fixed UE. In addition, the method of avoiding overlap during conflict is not limited to this. For example, the fixed UE with the smallest SLSSID uses a random number or the like to determine the change waiting time. As the change waiting time elapses, the fixed UE collects information about its surroundings to determine that a different fixed UE with the smallest SLSSID has changed its SLSSID. As a result of the collection, if it is determined that a different fixed UE with the smallest SLSSID has not changed its SLSSID, the fixed UE resets its own SLSSID based on the random number or the like to try to avoid a conflict. On the contrary, as a result of the collection, if it is determined that a different fixed UE with the smallest SLSSID has changed its SLSSID, the fixed UE ends the overlap avoidance process without changing its own SLSSID.

[0069] Second Exemplary Embodiment

[0070] Next, refer to Figure 8 The flowchart in describes a second exemplary embodiment of the present invention.

[0071] In the first exemplary embodiment, Figure 6 In the case where the result of the determination in S608 in is "No", the process proceeds to S609, in which the movable UE 303 determines whether it has detected a fixed UE, and performs the process in S610 or S611 depending on the result of the determination. Figure 6In the case where the result of the determination in S608 in is "No", subsequent processing is performed depending on whether the SLSSID transmitted from each UE has a specific value. In the second exemplary embodiment, it is assumed that the SLSSID notified to its surrounding by a UE (fixed UE, different UE connected to the fixed UE, etc.) performing independent operation has a value from 338 to 671. In addition, in the present exemplary embodiment, it is assumed that the fixed UE that wants to be used as a synchronization source sets its SLSSID at 338 and starts PC5 operation. Note that performing overlap avoidance processing similar to that in the first exemplary embodiment makes it possible to prevent overlap of multiple pieces of equipment having a SLSSID of value 338. In addition, for example, it is possible to adopt a configuration in which multiple pieces of fixed UE are allowed to give notifications about the SLSSID of value 338 when the fixed UEs are connected to each other in a wired or wireless manner and highly accurate time synchronization is achieved regularly. For example, in the case of achieving highly accurate time synchronization between fixed UE 301 and fixed UE 302, each of fixed UE 301 and fixed UE 302 sets the SLSSID at 338 and performs processing for giving notifications about the SLSSID.

[0072] In the second exemplary embodiment, the Figure 1 The configuration of the communication device 101 shown in Figure 2 The software function configuration 201 shown in FIG. In addition, in the second exemplary embodiment, Figure 3 The network 300 shown in FIG. 1 and also used in the second exemplary embodiment Figure 4 The configuration of a fixed UE is shown in FIG.

[0073] Figure 8 : is a flowchart describing the synchronization process performed by the communication device 101 in the second exemplary embodiment. Figure 8 In the flowchart in FIG. 1 , S601 to S608 are the same as those in the first exemplary embodiment. Note that, in the present exemplary embodiment, it is assumed that the communication device 101 is the mobile UE 305.

[0074] In the case where the result of the determination in S608 is "No", in the present exemplary embodiment, the mobile UE 305 determines whether the SLSSID transmitted from (notified by) each UE indicates 338 (S801). This determination is performed by the detection unit 208. In the present exemplary embodiment, as described above, it is assumed that the fixed UE 302 is a device having an SLSSID value of 338. The SLSSID from 338 to 671 means that it is a UE that performs independent operation or achieves time synchronization with a source (synchronization source) through communication via two or more hops (which is communication passing through different UEs).

[0075] In a case where the result of the determination in S801 is "Yes", the movable UE 305 operates in synchronization with the UE having the SLSSID of the value 338 (fixed UE 302) (S802).

[0076] In a case where the result of the determination in S801 is "No", the process proceeds to S611. In a case where the result of the determination in S608 is "Yes", the process proceeds to S606.

[0077] As described above, even in the case where the mobile UE 305 is out of the range of a more appropriate time synchronization source represented by a base station, GNSS, etc., the mobile UE 305 can be preferentially connected to the fixed UE among multiple UEs that perform independent operations or achieve time synchronization with the source via multiple hops. That is, the mobile UE 305 can stably connect to the fixed UE 301 or the fixed UE 302 that gives a notification about 338 as the SLSSID, and achieve stable synchronization in the physical layer.

[0078] Note that the fixed UE 301 and the fixed UE 302 can achieve highly accurate time synchronization through direct communication. For example, the fixed UE 301 and the fixed UE 302 can be connected to each other through a wired local area network (LAN) and achieve highly accurate time synchronization.

[0079] In the case where there are multiple fixed UEs that achieve highly accurate time synchronization, there are the following advantages. Even in the case where the mobile UE 305 is out of the range of synchronization (out of the range of the fixed UE 301) when viewed from the fixed UE 301, the mobile UE 305 can achieve synchronization with the fixed UE 302 within the range of synchronization (within the range of the fixed UE 301). The content of this exemplary embodiment is also effective in such a network 300, and can achieve stable synchronization in the physical layer.

[0080] Third Exemplary Embodiment

[0081] In the above-mentioned exemplary embodiments, the communication device 101 is the mobile UE 303 or the mobile UE 305. However, it is also possible to apply the present invention to a case where the communication device 101 is the fixed UE 302.

[0082] In the third exemplary embodiment, the Figure 1 The configuration of the communication device 101 shown in Figure 2 The software function configuration 201 shown in FIG. In addition, in the third exemplary embodiment, Figure 3 The network 300 shown in FIG. 1 and also used in the third exemplary embodiment Figure 4 The configuration of a fixed UE is shown in FIG.

[0083] The following will refer to Figure 6 Differences from the first exemplary embodiment are described.

[0084] In the case where the communication device 101 is a fixed UE 302, when Figure 6 When the process in starts, the fixed UE 302 starts operating with the built-in clock of the fixed UE 302 (S601).

[0085] In S602 , it is assumed that the fixed UE 302 performs scanning regarding the presence / absence of a priority synchronization device and detects the fixed UE 301 , the movable UE 304 , and the movable UE 305 .

[0086] In S603, the fixed UE 302 uses the priority synchronization source type checking unit 211 to determine whether sl-SyncPriority indicating the priority synchronization source of the fixed UE 302 is Fixed UE indicating the fixed UE.

[0087] In a case where the result of the determination in S603 is "Yes", the fixed UE 302 uses the detection unit 208 to determine whether it has detected the fixed UE 301 (S604).

[0088] In a case where the result of the determination in S604 is "Yes", the fixed UE 302 uses the synchronization processing unit 209 to operate in synchronization with the fixed UE 301 (S605).

[0089] In a case where the result of the determination in S603 is "No", the mobile UE 302 uses the priority synchronization source type checking unit 211 to determine whether sl-SyncPriority indicating the priority synchronization source of the fixed UE 302 is not set (S607).

[0090] In a case where the result of the determination in S607 is "Yes", the fixed UE 302 uses the detection unit 208 to determine whether it has detected gnss or gnbEnb (S608).

[0091] In a case where the result of the determination in S608 is "No", the fixed UE 302 uses the detection unit 208 to determine whether it has detected the fixed UE 301 (S609).

[0092] In a case where the result of the determination in S609 is "Yes", the fixed UE 302 uses the synchronization processing unit 209 to act in synchronization with the fixed UE 301 (S610).

[0093] Each of the processing when the result of the determination in S604 is "No", the processing when the result of the determination in S607 is "No", the processing when the result of the determination in S608 is "Yes", and the processing when the result of the determination in S609 is "No" is the same as the corresponding processing in the first exemplary embodiment.

[0094] In this way, even in the case where the communication apparatus 101 is the fixed UE 302, if the fixed UE is set as the synchronization source device (S603: Yes), the fixed UE 302 selects the fixed UE 301 as the synchronization source device. This enables stable synchronization.

[0095] Other Exemplary Embodiments

[0096] The present invention can be realized by providing a recording medium in which the program code of the software realizing the above-mentioned functions is recorded to a system or computer of the device and reading out and executing the program code stored in the recording medium by the system or computer (CPU or MPU) of the device. In this case, the program code itself read out from the storage medium realizes the above-mentioned functions according to the exemplary embodiment, and the storage medium storing the program code constitutes the present invention.

[0097] As storage media for supplying program codes, it is possible to use, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a compact disk read-only memory (CD-ROM), a compact disk recordable (CD-R), a magnetic tape, a nonvolatile memory card, a ROM, and a digital versatile disk (DVD).

[0098] Alternatively, the above-mentioned functions of the exemplary embodiments may be realized not only by reading out and executing the program code by the computer but also by an operating system (OS) operating on the computer performing a part or all of actual processing based on instructions of the program code.

[0099] Furthermore, the program code read out from the storage medium is written in a memory included in a function expansion board installed in the computer or a function expansion unit connected to the computer.

[0100] Alternatively, the above-mentioned functions may be realized by executing a part or all of actual processing by a CPU included in the function expansion board or the function expansion unit based on instructions of the program code.

[0101] The present invention is not limited to the above mentioned exemplary embodiments, and may be changed and modified in various ways without departing from the spirit and scope of the present invention. Therefore, the claims are attached to disclose the scope of the present invention.

[0102] This application claims the benefit of Japanese Priority Patent Application JP2022-111105 filed in the Japan Patent Office on Jul. 11, 2022, the entire contents of which are hereby incorporated by reference.

Claims

1. A communication device capable of performing sidelink communication, the communication device comprising: a detection unit configured to detect at least one different communication device capable of serving as a synchronization source and capable of performing sidelink communication; an acquisition unit configured to acquire predetermined information from each of the at least one different communication device detected by the detection unit; as well as A first setting unit, wherein the first setting unit is configured to set the different communication device from which the information has been acquired as a time synchronization source in a case where a predetermined operation setting regarding a synchronization priority has been made and the first setting unit determines, based on the predetermined information acquired by the acquisition unit, that there is a different communication device from which the information has been acquired among the at least one different communication device, the information indicating that the different communication device is a communication device of a predetermined type to be used as a synchronization source.

2. The communication device according to claim 1, wherein the acquisition unit is configured to acquire notification information in the side link communication from each different communication device, The first setting unit is configured as follows: in a case where the notification information includes information indicating that the different communication device is the predetermined type of communication device, determining that the different communication device is the different communication device from which the information has been acquired; and In a case where the predetermined operation setting has been made and the first setting unit determines that there is the different communication device from which the information has been acquired, the different communication device from which the information has been acquired is set as a time synchronization source. 3 . The communication device according to claim 2 , wherein the first setting unit is configured to set the synchronization source regardless of the intensity of the electric wave reaching the communication device.

4. The communication device according to any one of claims 1 to 3 further includes a second setting unit, which is configured to set an operation setting indicating a synchronization priority among multiple operation settings, and the multiple operation settings include at least the predetermined operation setting and a second operation setting different from the predetermined operation setting.

5. The communication device according to claim 4, wherein: In the case where the predetermined operation setting is made as an operation setting indicating a synchronization priority order, the first setting unit is configured to give priority to the different communication device from which the information has been acquired over a public wireless base station and a satellite positioning system and to set the different communication device as a time synchronization source.

6. The communication device according to any one of claims 1 to 5, wherein: In a case where multiple pieces of information indicating that different communication devices are the predetermined type of communication devices to be used as synchronization sources are acquired, the first setting unit is configured to set different communication devices having a side link synchronization signal ID (SLSSID) having a small value as the synchronization source.

7. The communication device according to any one of claims 1 to 6, wherein the predetermined type of communication device is a non-movable communication device.

8. The communication device according to claim 2 or 3, wherein the notification information includes information indicating that the communication device giving the notification about the notification information is immovable.

9. The communication device according to claim 4, wherein: In a case where the second setting unit sets an operation setting different from the predetermined operation setting as the operation setting indicating synchronization priority, the first setting unit is configured to set a public wireless base station or a global navigation satellite system (GNSS) as a time synchronization source.

10. The communication device according to claim 9, wherein: In a case where the different operation setting is performed as an operation setting indicating synchronization priority and the first setting unit fails to set a public wireless base station or GNSS as a synchronization source, the first setting unit is configured to determine a different communication device at a synchronization destination based on the value of the SLSSID and set the determined different communication device as the synchronization source.

11. The communication device according to claim 7, wherein: In case the communication device is a communication device installed in a fixed manner and connected to a different, non-movable communication device via a wired local area network (LAN), the communication device is configured to synchronize with the different, non-movable communication device via the preferred LAN.

12. A method of controlling a communication device, the communication device being capable of performing sidelink communication, the method comprising: detecting at least one different communication device capable of serving as a synchronization source and capable of performing sidelink communications; acquiring predetermined information from each of the at least one different communication device detected; as well as When predetermined operation setting regarding synchronization priority has been made and information indicating that a different communication device is a communication device of a predetermined type to be used as a synchronization source is acquired based on the acquired predetermined information, the different communication device from which the information has been acquired is set as a time synchronization source.

13. A program for causing a computer of a communication device to execute a method, the communication device being capable of performing sidelink communication, the method comprising: detecting at least one different communication device capable of serving as a synchronization source and capable of performing sidelink communications; acquiring predetermined information from each of the at least one different communication device detected; as well as In a case where a predetermined operation setting regarding synchronization priority has been made and it is determined based on acquired predetermined information that there is a different communication device from which information has been acquired, the different communication device from which the information has been acquired is set as a time synchronization source, the information indicating that the different communication device is a communication device of a predetermined type to be used as a synchronization source.

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