Information communication system and information communication device

Abstract

To provide an information communication system and an information communication device capable of connecting the information communication device without previously setting information on the information communication system.SOLUTION: An information communication system 100 includes: a connection candidate decision unit 707 that from a connection request list, decides a connection candidate of a communication address of another device and a communication address to be uniquely mapped; a connection response transmission unit 708 for transmitting a connection response including a communication address of another device CLb to the connection candidate; a connection determination unit 710 that refers to a connection response list based on received connection responses and determines that an information communication device 1 of a transmission source which is the same as that of another device CLb of a transmission destination of a connection request is connected to a virtual clock network; a network state generation unit 711 for generating a virtual clock network state to be formed with the determined other device CLb; and a virtual clock network formation unit 712 for forming the virtual clock network with the other device whose connection is determined.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an information communication system and an information communication device that synchronizes a plurality of information communication devices through communication. [Background technology]

[0002] A common time synchronization method between multiple information communication devices is, for example, the IEEE1588 Precision Time Protocol (PTP) described in Non-Patent Document 1. Non-Patent Document 1 defines a master device that has a reference time and a slave device that synchronizes with the time of the master device, and corrects the time of the slave device by periodically exchanging time synchronization packets between the master device and the slave device.

[0003] Specifically, the slave device estimates and corrects the time offset, which is the time difference between the master device and the slave device, using the master device's transmission time and slave device's reception time of a packet transmitted from the master device to the slave device, as well as the slave device's transmission time and master device's reception time of a packet transmitted from the slave device to the master device. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] “IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems.”IEEE Standard 1588-2008. [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-225880 Summary of the Invention [Problem to be solved by the invention]

[0005] In the PTP system, the Grandmaster Clock (GMC) is used as the reference clock supplied to the master device. The GMC is the clock that serves as the reference for synchronizing the clocks of all devices in the network.

[0006] In addition, PTP systems use network relay devices such as BCs and TCs to cancel out fluctuating propagation times and reduce the problem of reduced time synchronization accuracy caused by fluctuations in propagation time. BCs (Boundary Clocks) correct delays and fluctuations based on the time received from a higher-level master device and generate time as a master for lower-level slaves. TCs (Transparent Clocks) add the residence time within a relay device when relaying packets and send the time to the lower-level slaves.

[0007] When connecting information and communication devices to construct a new information and communication system that is synchronized with each other, it is necessary to set information about the information and communication system in advance in each information and communication device. Also, when connecting or disconnecting a new information and communication device to or from the information and communication system, it is necessary to set information about the information and communication system in each information and communication device in advance.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide an information and communication system and an information and communication device that can be connected to each other without setting information about the information and communication system in advance. [Means for solving the problem]

[0009] The present invention is an information communication system in which communication units of a plurality of information communication devices communicate information according to the time of their respective clocks, and each information communication device comprises a connection information storage unit that stores connection information received by the communication unit, including the communication addresses of other devices that are other information communication devices; a primary connection condition determination unit that determines, based on the connection information, whether or not the other devices satisfy a primary connection condition for forming a virtual clock network; a connection request transmission unit that transmits a connection request including the communication address of its own device, which is its own information communication device, to other devices that are determined to satisfy the primary connection condition; a secondary connection condition determination unit that determines, based on the connection request received from its own device, whether or not the own device and the other devices satisfy a secondary connection condition for forming a virtual clock network; and a connection request list that stores the connection requests that are determined to satisfy the secondary connection condition. a binding request storage unit that stores the binding responses received from the other devices as a binding response list; a binding candidate determination unit that refers to the binding requests in the binding request list and determines a virtual clock network that is connected to the other devices that have a communication address that is uniquely associated with the communication address of the other devices; a binding response transmission unit that transmits a binding response including the communication address of the other devices to the binding candidate device; a binding response storage unit that stores the binding responses received from the other devices as a binding response list; a binding determination unit that refers to the binding response list and determines that an information communication device that has the same transmission source as the other device that is the destination of the binding request has been connected to the virtual clock network; a network state generation unit that generates a virtual clock network state that represents the characteristics of a virtual clock network to be formed with the other devices that have been determined to be connected; and a virtual clock network formation unit that forms a virtual clock network with the other devices that have been determined to be connected based on the virtual clock network state.

[0010] The present invention is an information communication device in which a communication unit is a local device that communicates information with other devices that are other multiple information communication devices, and communicates information according to a clock that the local device has, and the information communication device includes a connection information storage unit that stores connection information including a communication address of the other devices received by the communication unit, a primary connection condition determination unit that determines whether the other devices satisfy a primary connection condition for forming a virtual clock network based on the connection information, a connection request transmission unit that transmits a connection request including the communication address of the local device, which is the information communication device itself, to the other devices that are determined to satisfy the primary connection condition, and a connection request transmission unit that transmits a connection request including the communication address of the local device, which is the information communication device itself, to the other devices in response to the connection request. The device has a connection response storage unit that, when another device that is a communication device receives a connection response including a communication address of a determined connection candidate, stores the received connection response as a connection response list; a connection determination unit that refers to the connection response list and determines that another device that has the same source as the other device that is the destination of the connection request has been connected to the virtual clock network; a network state generation unit that generates a virtual clock network state that represents the characteristics of the virtual clock network to be formed with the other device that has been determined to be connected; and a virtual clock network formation unit that forms a virtual clock network with the other device that has been determined to be connected based on the virtual clock network state. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an information communication system and an information communication device that can be connected to each other without setting information about the information communication system in advance. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of an information communication system according to an embodiment. [Figure 2] 1 is a functional block diagram of an information communication device constituting an information communication system according to an embodiment. [Figure 3] FIG. 1 is a diagram illustrating a mode of communication between information communication devices. [Figure 4] FIG. 2 is a functional block diagram of a control unit according to the embodiment. [Figure 5] FIG. 1 illustrates a communication aspect with propagation time symmetry. [Figure 6] FIG. 1 illustrates a mode of communication that does not have propagation time symmetry. [Figure 7] FIG. 10 is a diagram showing a synchronization state vector without errors due to variations in propagation time and time difference. [Figure 8] FIG. 10 is a diagram showing a synchronization state vector including errors due to fluctuations in propagation time and time difference. [Figure 9] FIG. 1 is a diagram illustrating a set of information communications in an information communication system according to an embodiment. [Figure 10] 10 is a graph showing a schematic relationship between a clock of an error-free information communication device and a virtual clock. [Figure 11] 10 is a graph schematically showing the relationship between a clock of an information communication device including an error and a virtual clock. [Figure 12] 10 is a graph showing a probability distribution of time fluctuations that an information communication device can take within a predetermined interval. [Figure 13] 10 is a flowchart illustrating a procedure for a synchronization control process according to an embodiment. [Figure 14] FIG. 10 is an explanatory diagram illustrating communication for acquiring transmission and reception times in synchronization control according to an embodiment. [Figure 15] 10 is a flowchart showing a procedure for processing to connect an information communication device to a virtual clock network. [Figure 16] 10 is a flowchart showing the procedure of a process for determining a joining candidate. [Figure 17] 10 is a flowchart showing a procedure for forming a virtual clock network. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an information communication system and an information communication device according to an embodiment will be described with reference to the drawings.

[0014] [composition] Fig. 1 is a schematic diagram of an information communication system 100 according to an embodiment. Fig. 2 is a functional block diagram of an information communication device 1 constituting the information communication system 100 according to the embodiment. Fig. 3 is a diagram showing a mode of communication between the information communication devices 1, and Fig. 4 is a functional block diagram of a control unit 70 in Fig. 2.

[0015] The information communication system 100 according to this embodiment is a system for communicating information between information communication devices 1 (devices A to E) via a synchronous network. In the information communication system 100, each information communication device 1 communicates information according to its own clock without using a reference clock. The reference clock is a clock that actually exists on the synchronous network, such as GMC, and serves as a reference for all information communication devices 1 in the synchronous network to synchronize their respective clocks. Each information communication device 1 achieves synchronization by transmitting and receiving synchronization information. The synchronous network is preferably a complete network. A complete network is a network in which each node can directly communicate with all other nodes. For example, the synchronous network NE shown in FIG. 1 is a complete network with the number of nodes N=5. In other words, N is the number of information communication devices 1 connected to the synchronous network NE. In FIG. 1, five information communication devices 1 are connected.

[0016] In this embodiment, there is no distinction between the roles of the master device and the slave device in each information communication device 1. In the following description, any one information communication device 1 may be referred to as the local device (CLa, i, etc.), and the information communication devices 1 other than the local device may be referred to as other devices (CLb, j, etc.). There are N-1 other devices, but for convenience they may be indicated by a common reference symbol. Each information communication device 1 has the same configuration, and can all function as the local device CLa and the other device CLb. In this embodiment, an example will be described in which the information communication devices 1 achieve synchronization by transmitting and receiving information via a wired connection, but wireless communication may also be used.

[0017] (Information and communication devices) The information communication device 1 includes a computer, and performs necessary calculations by having a processor including a CPU or the like execute a program that is stored in advance in a storage unit such as an HDD or SSD.

[0018] 2, the information communication device 1 has a communication unit 10, a clock 20, a timepiece 30, a storage unit 50, an external interface 60, and a control unit 70. For example, each of the units 10 to 70 is configured as hardware, but all or part of each of the units 10 to 70 may be configured as software including programs and data. Which part of the control unit 70 is configured as software can be changed as needed.

[0019] The communication unit 10 transmits and receives information to and from other information communication devices 1. That is, the communication unit 10 transmits information to the outside of the information communication device 1, receives information from the outside of the information communication device 1, or performs both of these. The communication unit 10 has a transmitter 11, a receiver 12, a transmission timing detection unit 13, and a reception timing detection unit 14.

[0020] The transmitter 11 is a device that transmits input information. Specifically, the transmitter 11 breaks down the information into its smallest components in chronological order and transmits the information to the outside. The packet length of the information (amount of communication information) is arbitrary and may be different for each communication. For example, an input unit that converts an audio signal input from a microphone into audio data is connected to the information communication device 1, and the audio data as information is input from the input unit to the information communication device 1.

[0021] The receiver 12 is a device that receives information from outside. Specifically, the receiver 12 reconstructs information that has been decomposed into minimum components in time series and received from outside the information communication device 1, and outputs the reconstructed information to other components within the information communication device 1. For example, a playback unit such as an ear receiver or speaker that outputs audio is connected to the information communication device 1, and the receiver 12 converts audio data into an audio signal and outputs the audio signal to the playback unit. In this way, the information that has been decomposed into minimum components in time series and transmitted and received allows the position of each element in time series, i.e., the information element position, to be identified.

[0022] Here, the information communicated by the information communication device 1, that is, the information transmitted by the transmitter 11 and the information received by the receiver 12, includes synchronization information for synchronizing time. The synchronization information is composed of synchronization timing or time information corresponding to the synchronization timing.

[0023] The transmission timing detection unit 13 detects the transmission timing. The transmission timing is the timing at which a predetermined information element position of the information transmitted by the transmitter 11 is transmitted to the outside of the information communication device 1. This transmission timing is detected based on the clock period of a clock 20 (described later) (in other words, the period of the pulses oscillated by the clock 20). In other words, the transmission timing is expressed based on an integer multiple of the clock period.

[0024] The transmission timing detection unit 13 can also output the detection result to other components within the information communication device 1. The information here is, for example, a packet, and in this case, the predetermined information element position (hereinafter referred to as the predetermined information element position) is a bit position.

[0025] The reception timing detection unit 14 detects the reception timing. The reception timing is the timing at which information received by the receiver 12 is received from outside the information communication device 1. This reception timing is detected based on the clock period of a clock 20 (described later). In other words, the reception timing is expressed as an integer multiple of the clock period. The reception timing detection unit 14 also outputs the detection result to other components within the information communication device 1.

[0026] FIG. 3 shows a configuration for wired communication as an example, in which, in packet transmission between information communication devices 1, specific bit positions within a packet are detected as transmission and reception timings, and the transmission interval and reception interval are calculated from adjacent transmission and reception timings, respectively.

[0027] The transmission timing and reception timing may both detect the position of the same smallest component, but as long as a predetermined relationship is maintained between the transmitting and receiving information communication devices 1 at each timing detection, it is not necessary to detect the same position, and any deviation in the detected element position can be ignored or corrected.

[0028] Furthermore, the transmission timing may be detected a predetermined time before or after the actual transmission timing, and the reception timing may be detected a predetermined time before or after the actual reception timing. These predetermined values ​​may be fixed within the communication unit 10, or may be set statically or dynamically from the outside.

[0029] The clock 20 oscillates at a predetermined frequency and outputs a signal that provides operation timing to each unit of the information communication device 1. As a result, each unit in the information communication device 1 operates in synchronization with the clock 20. The entire information communication device 1 may be synchronized simultaneously with a single clock 20, or multiple clocks 20 may be used to independently synchronize multiple functional units. This clock 20 has an inherent finite oscillation frequency tolerance. In other words, the clock 20 has an error (e.g., 20 ppm) relative to a predetermined oscillation frequency (e.g., 10 MHz). For example, a fixed-frequency oscillator such as a quartz crystal resonator can be used as the clock 20.

[0030] Even if the nominal frequencies of the clocks 20 of the information communication devices 1 are the same, there are actually individual differences. That is, there is a frequency deviation between the frequencies of the clocks 20 of multiple information communication devices 1. The clock 20 may receive an external frequency control signal and variably control the oscillation frequency in response to the signal.

[0031] The clock 30 uses the output signal of the clock 20 as the oscillation source to keep time, and outputs the relative time since the startup of the information communication device 1. The clocking may be synchronized with a divided frequency of the input clock signal. The advancement amount per clock may be variable, and even if the clock frequency is fixed, the drive frequency of the clock 30 may be intermittently controllable. The time is referenced in a specified unit, and this specified value may be fixed within the clock 30 or may be set statically or dynamically from the outside. The clock 30 outputs the relative time in response to a reference request from the outside, for example.

[0032] The storage unit 50 is a recording medium such as an HDD, SSD, memory, or register. The storage unit 50 stores information necessary for the control unit 70 to perform calculations. The time of the clock 30 corresponding to the transmission timing or reception timing described below is preferably stored in a recording medium that can be accessed only by hardware, without the intervention of a CPU or software. This is because jitter caused by software can be eliminated. It is important that the correspondence between the transmission and reception timing and time is not affected by software jitter, and after the transmission and reception timing and time are associated, the time may be stored in a slow-access area.

[0033] The memory serving as the storage unit 50 inputs and outputs any information and stores the information in a designated storage area. Information is stored in response to an external storage request, at which time the information to be stored and the storage area are input. Information is referenced in response to an external reference request, at which time the storage area for the reference information is input, and the information in the storage area specified by that input is output. Information may be stored only while the device is operating, or may be retained permanently, even when the device is stopped.

[0034] The external interface 60 (hereinafter also referred to as external I / F 60) connects the inside of the information communication device 1 with the outside, and inputs and outputs any information. The information includes transmitted and received data such as synchronization information, the time of the clock 30, and other information to be stored in the memory unit 50. Furthermore, the information communication device 1 may have a user interface such as a display device that can control and display the internal state.

[0035] The control unit 70 controls the overall operation of each unit of the information communication device 1. Fig. 4 is a functional block diagram of the control unit 70. As shown in Fig. 4, the control unit 70 includes a main control unit 71, a transmission / reception data I / F 72, a communication control unit 73, a scheduler 74, a time recording unit 75, a time acquisition unit 76, a time difference calculation unit 77, a virtual time difference calculation unit 78, and a synchronization control unit 79. The control unit 70 also includes a combination information transmission unit 701, a combination information storage unit 702, a primary combination condition determination unit 703, a combination request transmission unit 704, a secondary combination condition determination unit 705, a combination request storage unit 706, a combination candidate determination unit 707, a combination response transmission unit 708, a combination response storage unit 709, a combination determination unit 710, a network status generation unit 711, a virtual clock network formation unit 712, and a separation reception unit 713.

[0036] The main control unit 71 is linked to each unit within the control unit 70 and controls the operation of each unit within the control unit 70. The transmission / reception data I / F 72 converts information from the memory unit 50 and the external I / F 60 into a format that can be transmitted outside the device. The transmission / reception data I / F 72 also converts information received from outside the device into a format suitable for the control unit 70 and the memory unit 50.

[0037] The communication control unit 73 controls the operation of the communication unit 10. The communication control unit 73 inputs and outputs transmission and reception information between the communication unit 10 and the control unit .

[0038] The scheduler 74 sets a schedule (time) for transmitting or receiving information by the communication control unit 73. For example, the scheduler 74 on the transmitting side sets an interval for transmitting information, or sets a schedule for detecting the timing for transmitting information at a predetermined time.

[0039] The scheduler 74 of this embodiment sets the transmission time of the synchronization information and the transmission time of the synchronization information so that the transmission of the synchronization information, which is performed so that the information communication devices 1 acquire each other's transmission time of the synchronization information, are executed within a predetermined time period that can be considered to be a constant time difference. As will be described later, this predetermined time period is the minimum interval time during which the influence of the frequency deviation between the own device CLa and the other device CLb appears in the propagation time of information between the own device CLa and the other device CLb. The frequency deviation is the difference between the clock frequencies of the devices. For example, the transmission timing of the synchronization information including the transmission time from the own device CLa to the other device CLb and the transmission timing of the synchronization information including the transmission time from the other device CLb to the own device CLa are set to be within the predetermined time period.

[0040] The time recording unit 75 records the time when information is transmitted or received. That is, the time recording unit 75 associates the transmission timing of information detected by the transmission timing detection unit 13 with the time on the clock 30 at that transmission timing, and stores these in memory. The time recording unit 75 also associates the reception timing of information detected by the reception timing detection unit 14 with the time on the clock 30 at that reception timing, and stores these in memory. For example, the time recording unit 75 receives signals from the transmission timing detection unit 13 and the reception timing detection unit 14 indicating that the transmission and reception timing of the transmitted or received information has been detected, refers to the time on the clock 30, and associates this time with the transmission and reception timing.

[0041] Thus, in this embodiment, "time" refers to the time of the clock 30 corresponding to the detected reception timing or transmission timing of a predetermined information element position in the information, and "hours" refers to the difference between the times.

[0042] The time acquisition unit 76 acquires the transmission time of the synchronization information from its own device CLa, the reception time of the synchronization information transmitted from its own device CLa by other device CLb, the transmission time of the synchronization information from all other devices CLb, and the reception time of the synchronization information transmitted from all other devices CLb by its own device CLa. The transmission time and reception time of the own device CLa are acquired from the memory of its own device CLa. The reception time and transmission time of the other device CLb are acquired from the synchronization information received by its own device CLa from other device CLb and stored in memory.

[0043] The time difference calculation unit 77 calculates the time difference between the clock 20 of the device CLa and the clock 20 of all other devices CLb based on the transmission time of the device CLa, the reception time of the device CLa, the transmission times of all other devices CLb, and the reception times of all other devices CLb acquired by the time acquisition unit 76.

[0044] The virtual time difference calculation unit 78 calculates a virtual time difference, which is the time difference between the clock 20 of the own device CLa and the virtual clock, based on the time difference between the clock 20 of the own device CLa and the clocks 20 of all other devices CLb. The virtual time difference in this embodiment is the average value of the time differences between the clock 20 of the own device CLa and all the clocks 20. The virtual clock is not an actually operating clock, but an imaginary clock that can be regarded as a common time source for all information communication devices 1.

[0045] The synchronization control unit 79 synchronizes the clock 20 of the device CLa with the virtual clock based on the virtual time difference calculated by the virtual time difference calculation unit 78. That is, the synchronization control unit 79 performs time synchronization using the virtual time difference as a correction value. The synchronization control unit 79 performs synchronization control assuming that there is symmetry in the propagation time between the clock 20 of the device CLa and the virtual clock. For example, as described below, the synchronization control unit 79 calculates the time difference with respect to the virtual clock, that is, the time difference, and corrects the value kept by the clock 30 based on that time difference. For example, the correction may be performed by controlling the clock 30 itself. Alternatively, the correction may be performed based on the time difference when the clock 30 outputs the time. That is, the clock 30 itself may not be corrected, but the synchronization control unit 79 may control the clock 30 so that when the clock 30 outputs the time, it outputs a time corrected for the difference.

[0046] Furthermore, the control unit 70 has the following configuration to couple or separate the local device CLa and the other device CLb, the local device CLa and the virtual clock network, and the virtual clock networks themselves. In the following description, the information communication device 1 performing the processing of each unit will be referred to as the local device CLa, and the other information communication devices 1 will be referred to as the other device CLb, but as described above, each information communication device 1 has the same configuration and can function as the local device CLa or the other device CLb. Details of the processing of each unit and the information processed will be described later.

[0047] The coupling information transmitting unit 701 broadcasts coupling information MC including the communication address of other device CLb to its own device CLa. The coupling information storage unit 702 stores the coupling information MC including the communication address of other device CLb received by the communication unit 10. The primary coupling condition determining unit 703 determines whether other device CLb satisfies the primary coupling condition for forming a virtual clock network based on the coupling information MC.

[0048] The binding request sending unit 704 sends a binding request including the communication address of the own device CLa to the other device CLb that has been determined to satisfy the primary binding condition. The secondary binding condition determining unit 705 determines whether the own device CLa and the other device CLb satisfy the secondary binding condition for forming a virtual clock network, based on the binding request received from the own device CLa. The binding request storage unit 706 stores the binding requests that have been determined to satisfy the secondary binding condition as a binding request list. The binding candidate determining unit 707 references the binding requests in the binding request list and determines a binding candidate that is the own device CLa having a communication address that is uniquely associated with the communication address of the other device CLb.

[0049] The binding response transmitting unit 708 transmits a binding response including the communication address of the other device CLb to the binding candidate device CLa. The binding response storage unit 709 stores the binding response received from the other device CLb as a binding response list. The binding determination unit 710 refers to the binding response list and determines that the information communication device 1 having the same source as the other device CLb, which is the destination of the binding request, has been bound to the virtual clock network.

[0050] The network state generation unit 711 generates a virtual clock network state that indicates the characteristics of a virtual clock network to be formed with another device CLb that has been determined to be coupled. The virtual clock network formation unit 712 forms a virtual clock network with another device CLb that has been determined to be coupled based on the virtual clock network state. The separation reception unit 713 receives separation information that indicates that separation is required.

[0051] [Measurement of time difference when propagation times are symmetric] Next, the measurement of propagation time and time difference when there is symmetry in the propagation time will be explained with reference to Fig. 5. Fig. 5 shows the relationship between the time difference between the clocks and the propagation time of information between a pair of own device CLa and other device CLb, and the transmission and reception timing observed by the information communication, using wired communication as an example.

[0052] It should be noted that the synchronization information transmitted by the own device CLa and the other synchronization information transmitted by the other device CLb are intended to measure the timing for synchronization, and the synchronization information includes the transmission time of the own device CLa, etc., but the contents of the synchronization information and the other synchronization information are arbitrary.

[0053] As shown in FIG. 5, the device CLa transmits information at time t a,T and after a propagation time of d, the signal is transmitted to the b,R The other device CLb receives it at Δt b Later, other information is sent by the other device CLb at time t b,T After the same propagation time d, the device CLa transmits the a,R Receive at.

[0054] Here, the interval from transmission to reception in the own device CLa is Δt a and the interval from reception to transmission in the other device CLb is Δt b and the transmission timing t a,T The same timing as above is t' in other device CLb. a,TTherefore, the time difference g between the clock 20 of the other device CLb and the own device CLa at a certain moment can be calculated as shown in formula (1). Furthermore, the time difference between the clock of the own device CLa and the clock of the other device CLb at the same moment can be expressed as -g.

[0055] TIFF2025143064000002.tif11161 Note that, as described above, it is assumed that the propagation time d from the own device CLa to the other device CLb and the propagation time d from the other device CLb to the own device CLa are the same, that is, they are symmetrical in the direction of information communication.

[0056] From these conditions, the propagation time d can be calculated as shown in equation (2). TIFF2025143064000003.tif15159

[0057] Therefore, the time difference g between the clocks 20 can be calculated using equation (2) as shown in equation (3). TIFF2025143064000004.tif14158

[0058] The synchronization control unit 79 of the other device CLb can be time synchronized with its own device CLa by repeatedly adjusting the clock frequency and time so that the time difference g between the clocks 20 becomes 0. Similarly, the synchronization control unit 79 of its own device CLa can be time synchronized with the other device CLb by repeatedly adjusting the clock frequency and time so that the time difference -g between the clocks 20 becomes minimum.

[0059] If the clock frequencies of the local device CLa and the other device CLb are the same, that is, if the clock domain is single, time synchronization can be achieved by simply adjusting the time once. However, since there is generally a frequency deviation between the two clocks, clock frequency adjustment is essential for time synchronization. Even in systems where the clock frequency cannot be adjusted directly, time synchronization can be achieved by controlling the drive frequency of the clock 30 and repeatedly adjusting the advance of time per clock. In these frequency adjustments, closed-loop control is periodically performed, with the synchronization phase as input and the frequency adjustment value as output, and the output value is controlled so that the input synchronization phase becomes zero.

[0060] It should be noted that propagation time and internal delays between transmission and reception timings can be ignored or corrected depending on system requirements, etc. Also, instead of initiating transmission of synchronization information from the own device CLa, synchronization information may be transmitted from another device CLb. Furthermore, although one interface is sufficient for information communication, multiple interfaces may be used simultaneously, for example, by implementing separate transmission and reception interfaces.

[0061] [Effects of time difference and propagation time variations] The above explanation is based on the premise that the time difference is constant and the propagation time is symmetrical in the direction of information communication. However, the actual frequency deviation from the nominal frequency of the clock 20 between the information communication devices 1 varies and fluctuates from moment to moment. Therefore, the time difference between the information communication devices 1 also fluctuates, and depending on the network system to which the local device CLa and the other device CLb are connected, the propagation time is generally asymmetrical due to the influence of the information propagation path and communication arbitration, as shown in Figure 6.

[0062] That is, the time difference g between the own device CLa and the other device CLb at a certain moment b / a Then, after a certain period of time has passed, the time difference g between the same device CLa and another device CLb is a / b In addition, the propagation time d of information from the own device CLa to the other device CLb is b / a is the propagation time d of information from other device CLb to own device CLaa / b In general, the time difference in Figure 6 is expressed as g b / a and g a / b have the same sign, and g b / a ·g a / b ≧0. Furthermore, as mentioned above, the time difference and propagation time fluctuate from moment to moment, and the time difference g b / a [m] and propagation time d b / a [m] is the time difference g observed at different moments b / a [n] and propagation time d b / a It is common for [n] to be different from each other.

[0063] Here, from the relationship between the times in Figure 6, the propagation time d b / a ,d a / b and time difference g b / a ,g a / b Using this, equations (2) and (3) are rearranged as equations (4) and (5), respectively. TIFF2025143064000005.tif15162TIFF2025143064000006.tif13162

[0064] Equation (2) allows us to calculate the propagation time assuming symmetry, but equation (4) shows that the average propagation time includes a variable component of the time difference. Similarly, equation (3) allows us to calculate the time difference assuming the time difference is constant, but equation (5) shows that the average time difference includes a variable component of the propagation time. In this way, the inclusion of variable components of the time difference and propagation time leads to a decrease in the accuracy of time synchronization.

[0065] [Errors due to time difference and fluctuations in propagation time] We will explain the time synchronization error caused by fluctuations in time difference and propagation time in a time synchronization system. First, we combine equations (4) and (5) and transform them into a matrix form as shown in equation (6). TIFF2025143064000007.tif13156

[0066] Here, the two-dimensional rotation matrix R θis expressed as equation (7). TIFF2025143064000008.tif11161

[0067] Then, by focusing on the common factor in equation (6), R in equation (7) θ By using this, equation (6) can be transformed into equation (8). TIFF2025143064000009.tif14162

[0068] As shown in FIG. 7, the horizontal axis represents the time difference g when communication is performed from the own device CLa to another device CLb. b / a and propagation time d b / a The vertical axis represents the time difference g when communication is performed from other device CLb to own device CLa. a / b and propagation time d a / b Consider a two-dimensional space with components of (g b / a - g a / b ) T The time difference vector g, (d b / a d a / b ) T If we let d be the propagation time vector, then we can obtain the synchronization state vector s = (g d d g ) T can be interpreted as the sum of the time difference vector g and the propagation time vector d rotated by +π / 4 on the same space and scaling each dimension.

[0069] In the operation of equation (8), element g of the time difference vector g b / a , g a / b There is no fluctuation in the element d of the propagation time vector d. b / a , d a / b There is no change in g b / a =g a / b And d b / a =d a / b As shown in Figure 7, when g Ingredients and g d It can be seen that by orthogonally decomposing the components, it is possible to obtain the time difference and delay time without including any error.

[0070] However, in general, the time difference vector g and the propagation time vector d each contain a fluctuation error in their respective elements, as shown in Figure 8. Because the errors in each of the orthogonal components are compounded, it is not possible to remove the errors from the time difference and propagation time by simply manipulating equation (8), which leads to a decrease in time synchronization accuracy.

[0071] Since equations (4) and (5) are linearly dependent, an analytical solution cannot be found without introducing other independent operations, but by measuring only the transmission and reception timing of synchronization information, it is not possible to find new independent operations that result in the vectors shown in Figure 7. Therefore, a different approach must be introduced to remove the fluctuation error.

[0072] [Relationship between time difference fluctuation and frequency deviation] The oscillation frequency f of the clock 20 of each information communication device 1 used in time synchronization is a nominal frequency f N This includes a frequency deviation e relative to the oscillation frequency f[n]. Furthermore, the frequency deviation e varies from moment to moment depending on the mechanical and electromagnetic operating environment of the clock 20. Therefore, the relationship between the oscillation frequency f[n] and the frequency deviation e[n] at observation timing n can be expressed as in equation (9). Note that the frequency deviation e[n] is sufficiently smaller than 1, and r[n] represents the frequency ratio. TIFF2025143064000010.tif10157

[0073] FIG. 9 shows the relationship between the transmission / reception timing, the time difference, and the propagation time when communicating information from the own device CLa to another device CLb.

[0074] The nominal frequency of the clock 20 used for time synchronization in both the own device CLa and the other device CLb is the same. However, the frequency deviation of the own device CLa is e a [n], other device CLb is e b At this time, the frequency deviation of the other device CLb as seen from the own device CLa is (e b [n]-e a The frequency ratio r b / a [n] is r b / a [n]=1+(eb [n]-e a Similarly, the frequency deviation of the own device CLa as seen from the other device CLb can be expressed as (e a [n]-e b The frequency ratio r a / b [n] is r a / b [n]=1+(e a [n]-e b [n]).

[0075] If the clock frequencies of the own device CLa and other device CLb are different, the advance width of the clocks will also differ, resulting in a time difference from moment to moment. b / a [m]≠g b / a There are also observation timings where the frequency deviation is [n], and time calculations between devices require correction to take frequency deviation into account. If correction is not performed, errors will occur in the time calculations, leading to a decrease in time synchronization accuracy.

[0076] In FIG. 9, the average frequency ratio of the other device CLb seen from the own device CLa from timing m to timing n is expressed as r b / a If we set [n,m], the relationship in equation (10) can be stated. TIFF2025143064000011.tif20158

[0077] From this equation (10), g b / a [n]=g b / a [m]+(r b / a [n,m]-1)(t a,T [n]-t a,T It can be seen that the time difference changes due to the influence of frequency deviation.

[0078] In equation (10), the frequency deviation does not affect the propagation time, and no correction is required. This is because the nominal frequency f N The minimum time L that occurs between the observation times of the two devices with apparent frequency deviation e[n] g [n] can be expressed as in equation (11), but the propagation time is generally the minimum time L g This is because the period T N=1 / f N It states that: TIFF2025143064000012.tif13158

[0079] That is, L g [n] is the time T for one period corresponding to the nominal frequency plus the observed time difference between the devices. N is the interval time to be added or subtracted. Therefore, within this interval time, the time difference is at most ±T N Only the value changes.

[0080] Also, L g [n] changes from moment to moment and cannot be calculated directly. However, if the allowable frequency deviation of the clock 20 is e, the absolute value of the apparent frequency deviation between devices using the same type of clock 20 will not exceed |2e|. Therefore, L g =T N Let / |2e| be the minimum time for which the time difference between these clocks 20 is constant.

[0081] [Virtual clock formation] Next, we will explain how to create a virtual clock v for synchronizing the clocks 20 of all information communication devices 1. In the following explanation, the symbols for the "device" that is the information communication device 1 and the "clock" included therein will be the same.

[0082] The transmission time of the synchronization information of the device i including the clock i is t i,T Then, {t i,T} j A i,T The same timing is the time of another device j including a clock j with the same timing. The same timing is an ideal single timing in which the time of each clock i and j is observed with a propagation time of 0 in an observation system including clocks i and j. By definition, t i,T is {t i,T} i It can also be written as:

[0083] Synchronization information is stored at time t i,T The time difference between clock j and clock i at the time of transmission is g j / iis newly defined as equation (12). TIFF2025143064000013.tif14158

[0084] N pieces of information communication devices 1 are connected to a synchronization network NE, and one of the information communication devices 1, i, is implemented with a clock i. The transmission time t of the synchronization information of the device i is i,T and the sum of the transmission times of the synchronization information of all devices k at the same timing, that is, the sum of the transmission times of all information communication devices 1, can be expressed as equation (13). TIFF2025143064000014.tif15159

[0085] Equation (13) is transformed into an equation to obtain equation (14). In equation (14), the first term on the rightmost side corresponds to the sum of the time differences between all N information communication devices 1 as seen from device i. Although device i is included in all information communication devices 1, the time difference between device i and other devices is 0. The second term on the rightmost side is N times the transmission time of the synchronization information of device i. TIFF2025143064000015.tif16156

[0086] From equation (12), equation (14) can be expressed as equation (15). TIFF2025143064000016.tif16156

[0087] Multiplying both sides of equation (15) by 1 / N yields equation (16). The left side of equation (15) is the average value of the transmission times of all information communication devices 1, and the first term on the right side is the average value of the time differences between device i and all information communication devices 1 as seen from device i. TIFF2025143064000017.tif15156

[0088] In this case, the left side of equation (16) is i,TAssume the existence of device v that includes clock v that has the same time as clock i. This clock v is called virtual clock v. If the first term on the right-hand side of equation (16) is the time difference between virtual clock v observed from clock i, equation (16) can be rewritten as equation (17) assuming device v, which becomes a modified version of equation (12). In other words, virtual clock v can be formed by looking at the time differences between clock i and all other clocks and taking the average. TIFF2025143064000018.tif11156

[0089] This t i,T At the same time, device j sends synchronization information at time t j,T If you send to t j,T ={t i,T} j And i,T ={t j,T} i Since {t i,T} v ={t j,T} v Thus, both device i and device j can assert the existence of the same device v.

[0090] t in equation (17) i,T The device j sends the synchronization information at time t j,T If equation (17) holds true for other device j when transmitting to the virtual clock v, each device connected to this synchronization network NE can transmit to the virtual clock v with a time difference g v / k By performing time synchronization control to cancel the time synchronization, it is possible to synchronize with the device v whose existence is assumed.

[0091] The relationship between such a virtual clock and the clock of the information communication device 1 is shown schematically in Fig. 10. The horizontal axis of Fig. 10 indicates the passage of absolute time, and the vertical axis indicates the time difference between each clock. The virtual clock is indicated by Cv, and the clocks of the information communication device 1 are indicated by C1 to C3. Of the four points enclosed by each of the three dotted ellipses in Fig. 10, the line connecting the points that represent the average of the time differences of C1 to C3 represents the virtual clock Cv.

[0092] t of clock C11,T and the virtual clock Cv's {t 1,T} v The time difference between v / 1 , t of clock C2 2,T and the virtual clock Cv's {t 2,T} v The time difference between v / 2 , t of clock C3 3,T and the virtual clock Cv's {t 3,T} v The time difference between v / 3 The clocks C1, C2, and C3 have the time difference g v / 1 , g v / 2 , g v / 3 If you cancel this, you will be able to synchronize.

[0093] However, in Figure 10, only the time difference is shown, excluding errors including deviations in propagation time and frequency. In reality, the time difference contains errors. This error is shown diagrammatically in Figure 11. Figure 11 shows the time difference between clocks C1 and C2, with a minimum unit of ±1 / f N This error will be discussed later.

[0094] [Effect of time difference fluctuations on virtual clocks] It is common for different devices i and j to transmit synchronization information at different times. In addition, the propagation time of the synchronization information is longer than 0, and the reception timing is different from the transmission timing. The interval between these timings is the time L during which the time difference fluctuation due to the clock frequency deviation is observed. g Consider the case where the value is within the range.

[0095] Without loss of generality, let the nominal frequency of the clock implemented by each device be f N Then, each clock operates independently, so device k operates at time L g The time variation Δk (time difference variation from an ideal clock with a tolerance of 0) that can be taken within the range is expressed as {-1 / f N ,0,1 / f N}. That is, even if L gEven if the time difference is repeatedly observed at intervals shorter than ±2 / f, the smallest unit in which the time difference fluctuation can be observed is ±2 / f. N It is possible to observe changes in

[0096] Similarly, the time variation Δv that the virtual clock v formed in the synchronization network NE to which N devices are connected can have in this interval can be calculated as shown in equation (18). TIFF2025143064000019.tif15152

[0097] However, the sum of Δk forms a trinomial distribution, and its probability distribution is shown in Figure 12. Therefore, the probability that the equality on both sides of equation (18) holds is at most 1 / 3. N That is, Δk is all -1 / f N or 1 / f N That is, at most 2 / 3 N The probability that Δk can be {-1 / f N ,0,1 / f N} appears with equal probability, and in Figure 12, it is normalized to the range of ±1. The probability of it being less than -0.5 or more than 0.5 is 8 × 10 when N = 10. -2 , 8×10 for N=20 units -3 , 1×10 when N=50 units -5 , 5×10 for N=100 units -10 is.

[0098] Therefore, the time difference variation Δg between the virtual clock v observed from device k v / k = Δv-Δk -2 / f N <Δg v / k <2 / f N The range of Δg v / k =±2 / f N This is because the condition for the equality of equation (18) to be true is met. i =-1 / f N , Δ k≠i =1 / f N When Δ v =(N-2) / Nf N and Δg v / kis the maximum value (2N-2) / Nf N <2 / f N Take Δ i =1 / f N Like Δ k Similarly, when the sign of Δg is inverted, v / k is the minimum value - (2N-2) / Nf N >-2 / f N Take.

[0099] Using this time difference fluctuation, g i / j =-(g j / i +Δg j / i ), the expected value of the first term on the right-hand side of equation (5) when device i observes other device j can be expressed as equation (19), paying attention to the change in the definition of the time difference in equation (12). This means that Δ v From the probability distribution (Figure 12), the second term on the second side of the right side, Δg v / i / 2 is -1 / 2f N Beyond 1 / 2f N Since it can be considered to take a range less than 1 / f N can be rounded to 0. TIFF2025143064000020.tif16154

[0100] Therefore, the time fluctuation of each device is at most ±1 / f N If the observation of equation (19) is completed within the period when only the virtual clock occurs, the time difference with the virtual clock can be obtained without time difference errors due to fluctuations in the clock frequency deviation.

[0101] Under this condition, the time difference g calculated by equation (17) for each device k at different times is v / k is the time difference relative to the same virtual clock.

[0102] [Effect of propagation time variations on virtual clocks] Until now, the ideal time difference g j / i However, in reality, the propagation time d is longer than 0 and is different as shown in equation (5). j / i ,d i / j The time difference can be observed through this.

[0103] g a / b =g b / a +Δg b / a ,Δd b / a =d b / a -d a / b Then, equation (5) is rewritten as equation (20). TIFF2025143064000021.tif12152

[0104] For device i and other devices k connected to the synchronization network NE, time L g By completing the transmission and reception of synchronization information within the time limit, and calculating equation (20) while paying attention to the change in the definition of the time difference in equation (12), and taking their expected values, equation (21) can be obtained. TIFF2025143064000022.tif15157

[0105] In other words, the error due to the propagation time deviation included in the time difference between device i and the virtual clock is the expected value (average value) of the error due to the propagation time deviation between device i and each other device k. Therefore, time synchronization with the virtual clock can reduce errors due to the propagation time deviation of synchronization information.

[0106] Furthermore, the propagation time deviation Δd j / i [i] and the propagation time deviation Δd between the timing of device j i / j [j] is Δd j / i [i]=-Δd i / j If synchronization information is sent and received while maintaining the relationship [j], the expected value of the time difference error due to the propagation time deviation can be calculated as follows: Δd i / j [j] is Δd j / i Since it has the opposite sign to [i] but the same absolute value, it becomes 0. The leftmost side of equation (22) is the expected value of the second term on the rightmost side of equation (21), which is the expected value of the error due to the propagation time deviation from the virtual clock, and this becomes 0. In other words, each information communication device 1 is premised on the fact that the communication unit 10 transmits and receives synchronization information while maintaining the relationship in which the absolute value of the propagation time deviation at the timing of device i is equal to the absolute value of the propagation time deviation at the timing of other device j. TIFF2025143064000023.tif16158

[0107] That is, the expected value of the synchronization phase difference due to time synchronization to the virtual clock in the entire synchronization network NE is 0, realizing balanced and accurate time synchronization.

[0108] [Operation] The procedure for multiple devices connected to a synchronization network NE to synchronize their time with a virtual clock formed in this synchronization network NE according to the present embodiment will be described with reference to the flowchart in Fig. 13 and the explanatory diagram in Fig. 14. In the following description, any one of the information communication devices 1 will be referred to as the local device i, and an information communication device 1 other than the local device i will be referred to as another device j. The flowchart in Fig. 13 shows the flow of processing in the local device i.

[0109] First, as shown in FIG. 14, the communication control unit 73 of the own device i and the other device j sends a time L that can be considered as a constant time difference to the communication unit 10 according to the scheduler 74. g The synchronization information is multicast within the range of t , and then unicast. As a result, the time acquisition unit 76 of the device i acquires four transmission and reception times (step S101). The four transmission and reception times are the transmission time t i,T , and the other device j receives it at the reception time t j / i,R , the transmission time t of synchronization information from all other devices j j,T , the reception time t when the device i receives the synchronization information transmitted from all other devices j i / j,R is.

[0110] More specifically, the device i transmits synchronization information simultaneously (multicast), and other devices j≠i receive this synchronization information. i,T The other device j is t j / i,R Similarly, other devices j≠i broadcast synchronization information, and the device i receives this synchronization information. At this time, the other device j receives t j,T The device i is t i / j,R(Process 2) The time L that all the own device i and other device j can consider processes 1 and 2 to have a constant time difference is obtained. g Execute within.

[0111] Then, the own device i sends the t i,T and t in process 2 i / j,R The synchronization information including the time stamp is transmitted by unicast, and the other device j receives this synchronization information (process 3). j,T ,t j / i,R ,t i,T ,t i / j,R Furthermore, other device j≠i sends the t j,T and t of process 1 j / i,R The device i receives the synchronization information including t i,T ,t i / j,R ,t j,T ,t j / i,R (Process 4). All the information communication devices 1 execute Processes 3 and 4.

[0112] Next, the time difference calculation unit 77 of the device i calculates the time difference g with all other devices j≠i using equation (23). d,j / i is calculated (step S102). TIFF2025143064000024.tif14158

[0113] Then, the virtual time difference calculation unit 78 of the device i calculates the time difference g with the virtual clock v using equation (24). d,v / i The (virtual time difference) is calculated (step S103). TIFF2025143064000025.tif17157

[0114] Device i is now at a time difference of g d,v / i The time or clock frequency is adjusted so as to add the time to the virtual clock v, and the time is synchronized with the virtual clock v (step S104).

[0115] All the information communication devices 1 execute steps S102, S103, and S104, and if they wish to continue time synchronization, they wait for a predetermined period of time and then return to step S101. j / i [i]=-Δd i / j The transmission and reception of synchronization information is realized by maintaining the relationship [j].

[0116] [Autonomous formation of virtual clock networks] If all information communication devices 1 connected to the synchronization network NEs have been determined before the time synchronization system is put into operation, it is possible to form a virtual clock and synchronize time with the virtual clock using the above principle. However, there are cases where it is not possible to determine in advance which information communication devices 1 to connect to the synchronization network NE, and it becomes necessary to connect a new information communication device 1 later and set it in the time synchronization system. There are also cases where it becomes necessary for one of the information communication devices 1 to dynamically join or separate from the synchronization network NE. Furthermore, there are also cases where it becomes necessary for synchronization network NEs to join or separate from each other. In such cases, a further principle for forming a virtual clock is required.

[0117] Here, a synchronization network NE in which synchronization by a virtual clock has already been established is called a virtual clock network. Furthermore, connecting a new information communication device 1 or another virtual clock network to a virtual clock network is called coupling, and disconnecting it is called separation. Furthermore, an information communication device 1 that is not coupled to a virtual clock network is called a single device CLs. Note that even when coupling and separating virtual clock networks, each information communication device 1 can function as either its own device CLa or another device CLb.

[0118] The information communication device 1 periodically broadcasts (multicasts) coupling information MC at predetermined intervals. By receiving the coupling information MC, the information communication device 1 coupled to the virtual clock network can learn of the existence of other information communication devices 1 on the synchronization network NE.

[0119] The coupling information MC includes at least the communication address of the information communication device 1. The communication address is information that can uniquely identify the information communication device 1, and is information that specifies the destination and source of communication in communication between the information communication devices 1. By receiving the coupling information MC, the information communication device 1 can communicate with other information communication devices 1. The coupling information MC may be included in the synchronization information.

[0120] The information communication devices 1 that do not receive any of the combined information MC broadcast by the other information communication devices 1 are single devices CLs that are not connected to the virtual clock network and cannot perform time synchronization control, so the clocks 20 of the single devices CLs are self-running. In other words, they operate only by their own clocks 20 without being affected by the other clocks 20.

[0121] (Combination of single devices) The procedure by which multiple information communication devices 1 connect to a synchronization network NE and simultaneously join to a virtual clock network will be described below with reference to the flowchart in Fig. 15. In this case, it is assumed that all the information communication devices 1 are single devices CLs.

[0122] <Send binding information> The device CLa receives the combined information MC broadcast by the combined information transmitting unit 701 of the other device CLb, and the combined information storage unit 702 stores the received combined information MC as a combined information list (step S201). The combined information list is configured as a FIFO. The stored combined information MC can be arbitrarily deleted from the combined information list upon completion of reference, etc. The combined information MC may include primary combined information that serves as a condition for determining whether the single device CLs or virtual clock network that received the combined information MC should form a virtual clock network and combine with the sender of the combined information MC.

[0123] The primary connection information includes the virtual clock network identifier, the number of nodes, the network set identifier, the time reliability, the time dependency, and the minimum time L gThe information includes information such as the above. The virtual clock network identifier is information that can uniquely identify each virtual clock network. The number of nodes is the number of information communication devices 1 connected to the virtual clock network. Since a single device CLs can be interpreted as a virtual clock network with one node, in the primary coupling information of the single device CLs, the virtual clock network identifier may be set to the communication address of the information communication device 1 and the number of nodes may be set to 1. The network set identifier is information that can identify each of multiple virtual clock networks. Time reliability is information that indicates whether the time of the information communication device 1 is set to Coordinated Universal Time, etc. Time dependency indicates whether the time of the information communication device 1 can be updated by means other than time synchronization with the virtual clock.

[0124] <Judgment of primary join conditions and sending join request> The primary association condition determination unit 703 of the information communication device 1 extracts the association information MC sequentially from the top of the association information list, and determines whether or not a virtual clock network can be formed by combining the association information MC with the single device CLs that is the sender of the association information MC (step S202). If it is determined that a virtual clock network can be formed, the association request transmission unit 704 transmits an association request UC_REQ to the single device CLs by unicast (step S203).

[0125] A virtual clock network can be formed when the primary connection condition is satisfied. This connection request UC_REQ includes at least the communication address of the own device CLa, and another device CLb that has received the connection request UC_REQ can communicate with the own device CLa.

[0126] The primary association condition may be, for example, a match of the network set identifiers. In this case, if the network set identifiers in the primary association information of the device CLa match all or part of the network set identifiers in the association information MC, the device CLa transmits the association request UC_REQ.

[0127] The primary association condition may also be a match of time reliability. In this case, the association request UC_REQ is sent according to the time reliability. For example, association is performed only with devices with time reliability. Alternatively, association is performed if any device, including the own device CLa, has time reliability.

[0128] The primary combination condition may also be a match of time dependencies. In this case, even if both have time reliability, if either the own device CLa or the time dependency in the combination information MC is dependent, the combination request UC_REQ is transmitted.

[0129] In addition, the primary coupling condition is the minimum time L g is within a predetermined range, in which case L g If the value is within a predetermined range, a combination request UC_REQ is sent. These primary combination conditions may be any combination of two or more.

[0130] Furthermore, the primary combination condition determination unit 703 may determine that the primary combination condition is met when it receives the combination information MC. In other words, the combination request transmission unit 704 always transmits the combination request UC_REQ when it receives the combination information MC. This is also called unconditional.

[0131] <Receiving join requests and determining secondary join conditions> The joining request UC_REQ may include secondary joining information, which is a condition for the information communication device 1 (single device CLs or information communication device 1 in a virtual clock network) that receives this information to determine whether to form a virtual clock network and join with the sender of the joining request UC_REQ.

[0132] The secondary combination information includes information such as a virtual clock network identifier, the number of nodes, and a network set identifier. The secondary combination condition determination unit 705 of the information communication device 1 (other device CLb) that received the combination request UC_REQ determines whether it is possible to form a virtual clock network by combining with the information communication device 1 that sent the combination request UC_REQ (step S204). If it is determined that it is possible to form a virtual clock network, that is, if the secondary combination conditions are met, the combination request storage unit 706 stores the combination request UC_REQ as a combination request list. The combination request list is configured as a FIFO. A stored combination request UC_REQ can be arbitrarily deleted from the combination request list upon completion of reference, etc.

[0133] The secondary combining condition may be, for example, a match of all or part of the network set identifiers. In this case, if the network set identifiers in the secondary combining information of the other device CLb and the network set identifiers in the combining request UC_REQ can be matched, the combining request storage unit 706 stores the combining request UC_REQ as a combining request list (step S205).

[0134] The secondary combining condition may also be that combining information MC has already been received from the own device CLa, which is the same sender of the combining request UC_REQ. In this case, if combining information MC has already been received from the own device CLa, which is the sender of the combining request UC_REQ, the combining request storage unit 706 stores the combining request UC_REQ as a combining request list. These secondary combining conditions may be combined.

[0135] Furthermore, the secondary combination condition may be satisfied when a combination request UC_REQ is received. In other words, when a combination request UC_REQ is received, the combination request storage unit 706 always stores it as a combination request list. In this case, it is also called unconditional. Note that if it is determined in steps S202 and S204 that a virtual clock network cannot be formed, the virtual clock network is not formed.

[0136] <Determining binding candidates> The joining candidate determination unit 707 of the information communication device 1 refers to the joining request UC_REQ in the joining request list received periodically at predetermined intervals, compares the communication address of each source information communication device 1 in the joining request UC_REQ stored in the joining request storage unit 706 with the communication addresses of other information communication devices 1, and determines the source information communication device 1 having a uniquely associated communication address (step S206). This information communication device 1 is called a joining candidate, and this determination procedure is called a joining function. Note that once a joining candidate has been determined, the process of determining a new joining candidate by referring to the joining request list is paused.

[0137] The interval time for referring to the association request list may be the smaller of a proportional value of the interval from the timing of transmission of the association request UC_REQ received immediately after the first or previous reference to the association request list to the timing of transmission of the last association request UC_REQ, or the maximum reference interval of the association request list. The proportional value of the interval of transmission timing is a time that allows sufficient reception of the UC_REQ sent from the other device CLb to the own device CLa. If all information communication devices 1 transmit UC_REQ at approximately the same interval, the own device CLa can be expected to receive all UC_REQs from the other devices CLb within a time period before and after the interval time. The maximum reference interval is a set value for each information communication device 1.

[0138] The join function is a function that outputs a communication address of a join candidate based on the join request list and the communication address of the information communication device 1 (other device CLb). The join function of this embodiment outputs a communication address of a join candidate from the input join request list and the communication address of the information communication device 1 by the following processing procedure. This processing will be explained with reference to the flowchart in FIG.

[0139] [1] From the association request list, extract the communication addresses of the source information communication devices 1 in all association requests UC_REQ, convert the communication addresses into integer values ​​(hereinafter referred to as communication address values), and store the communication address values ​​in the communication address value list (step S301).

[0140] [2] The communication address of the own information communication device 1 is converted into an integer value (communication address value), and the nearest communication address value is extracted from the communication address value list (step S302). The nearest communication address value refers to the one whose absolute value of the difference from the communication address value of the source information communication device 1 is the smallest.

[0141] [3] If only one nearest communication address value can be extracted (1 in step S303), the communication address corresponding to that value is output as a combination candidate (step S311), and the procedure ends.

[0142] [4] If two nearest communication address values ​​can be extracted (step S303-2), that is, if the difference between the two nearest communication address values ​​and the communication address value of the information communication device 1 is different in sign but the absolute values ​​match, the procedure branches depending on whether the absolute values ​​are odd or even.

[0143] [5] If the two communication address values ​​are different, one odd and the other even (YES in step S304), and if the communication address value of the own information communication device 1 is odd (YES in step S305), select the even communication address value (step S306). If the own communication address value is even (NO in step S305), select the odd communication address value (step S307). The communication address corresponding to the selected communication address value is output as a combination candidate (step S311), and the procedure ends.

[0144] [6] If the two communication address values ​​are both odd or even and are the same (NO in step S304), the communication address values ​​are input to the update function f(x) shown in the following equation (25) (step S308), and the procedure branches depending on whether the two output values ​​are odd or even. TIFF2025143064000026.tif13155

[0145] [7] If the two update function output values ​​are both odd or even and are the same (NO in step S309), the process using the update function is repeated (step S308).

[0146] [8] If the two update function output values ​​are different, one odd and the other even (YES in step S309), and if its own communication address value is odd (YES in step S305), select the even communication address value (step S306). If its own communication address value is even (NO in step S305), select the odd communication address value (step S307). The communication address corresponding to the selected communication address value is output as a combination candidate (step S311), and the procedure ends.

[0147] <Send join response> 15, the binding response transmitting unit 708 of the information communication device 1 transmits a binding response UC_RSP to the information communication device 1 of the binding candidate (step S207). This binding response UC_RSP includes at least its own communication address, and it is assumed that the information communication device 1 that receives the binding response UC_RS RSP can communicate with its own information communication device 1.

[0148] The binding response storage unit 709 of the information communication device 1 receives the binding response UC_RSP transmitted by the other device CLb and stores it in order as a binding response list (step S208). The stored binding response UC_RSP can be arbitrarily deleted from the binding response list when the reference is completed, etc. The binding response list is configured as a FIFO.

[0149] The connection response UC_RSP may be configured to include all or part of the virtual clock network state, which will be described later, in the virtual clock network to which the information communication device 1 is connected.

[0150] Following transmission of the binding response UC_RSP, the binding determination unit 710 of the information communication device 1 periodically refers to the binding response list at predetermined intervals, and when a binding response UC_RSP including an information communication device 1 that is the same source as the information communication device 1 that is the destination of the binding response UC_RSP is found, it determines that the information communication device 1 has been bound to a virtual clock network consisting of two nodes, the own device CLa and the other information communication device 1 (other device CLb) (step S209). Then, it generates a network state (step S210) and executes a virtual clock network formation process (step S211). Here, the source of the binding response UC_RSP is a single device CLs.

[0151] <Creating a virtual clock network> Next, the procedure of the process for forming a virtual clock network will be described with reference to the flowchart of FIG. [1] The coupled own device CLa and other device CLb stop sending and receiving all information such as synchronization information and coupling information MC, reset all lists, and each completes operation as a single device CLs (step S401).

[0152] [2] The network state generation unit 711 of the information communication device 1 generates a virtual clock network state that represents the characteristics of the virtual clock network (step S402). The virtual clock network state is composed of information such as a node list, a virtual clock network identifier, the number of nodes, the node order, the representative node, and time synchronization characteristics.

[0153] The node list is composed of primary coupling information including the communication address in the coupling information MC received from the coupling candidate, or primary coupling information including all elements of the node list in the virtual clock network state of the received coupling response UC_RSP and including the communication address of the own device CLa.

[0154] The virtual clock network identifier is information that can uniquely identify each virtual clock network, and is set according to the node list. For example, the virtual clock network identifier may be set to the communication address of the information communication device 1 that has the smallest communication address value in the node list.

[0155] The number of nodes is the number of information communication devices 1 connected to the virtual clock, and is the number of elements in the node list. The node order is formed by an order list of the information communication devices 1 when each information communication device 1 operates in an orderly manner within the network. For example, the node order may be formed by sorting the communication address values ​​of each information communication device 1 in ascending order. The node at the top of the node order is called the top node, and the node at the bottom is called the bottom node.

[0156] The representative node is the information communication device 1 that is in charge of communication when the virtual clock network interfaces with the outside. For example, the representative node may be the information communication device 1 that has the smallest communication address value.

[0157] The time synchronization characteristics consist of information such as the synchronization information broadcast timing, the synchronization information broadcast interval, the synchronization information individual transmission timing, the synchronization information individual transmission interval, and the time synchronization characteristic setting value. The synchronization information broadcast timing is the timing at which the first node broadcasts synchronization information and is expressed as absolute time or relative time. The synchronization information broadcast interval is the interval time between the broadcast transmission of synchronization information between a node and its next node.

[0158] The synchronization information individual transmission timing is the timing at which the first node individually transmits synchronization information, and is expressed as absolute time or relative time. The synchronization information individual transmission interval is the individual transmission interval time of synchronization information between a node and its next node.

[0159] The time synchronization characteristic setting value is a setting value of the virtual clock network that consists of information such as the individual transmission order of synchronization information and time synchronization accuracy. The individual transmission order of synchronization information is the individual transmission order of synchronization information paired between a source node and a destination node. The time synchronization accuracy is the time synchronization accuracy with the virtual clock that the virtual clock network expects.

[0160] The time synchronization characteristics are the number of nodes, the minimum time in the node list, L gThe time synchronization accuracy is set based on the time synchronization accuracy of the virtual clock, and is updated each time time synchronization with the virtual clock is completed, in preparation for the next time synchronization. Each node determines its own synchronization information transmission timing based on the time synchronization characteristics.

[0161] The virtual clock network state may exist and be managed in a single device CLs, but it is set to a state that indicates that it is a single device CLs. In this case, the generation of the virtual clock network state can be interpreted as the update of the virtual clock network state.

[0162] [3] All information communication devices 1 in the virtual clock network share the virtual clock network state (step S403). To share, the representative node may generate the virtual clock network state and distribute it to all other nodes, or each node may individually generate the virtual clock network state using the same generation method.

[0163] [4] Depending on the time reliability or time dependency, time synchronization is performed in advance to roughly adjust the time between the two information communication devices 1 (step S404). This rough adjustment can shorten the time required for the final synchronization process, but is not necessarily required. Here, the two information communication devices 1 are referred to as device A and device B.

[0164] For example, if device A has reliable time and device B has not, or if both devices have reliable time, and if device A does not have a time dependency and device B has a time dependency, device A will synchronize its time with device B.

[0165] When the binding information MC, binding request UC_REQ, or binding response UC_RSP is included in the synchronization information and transmitted, this time synchronization can be performed by using the synchronization equation to time-synchronize device A with device B. Also, when the time of device B is transmitted to device A together with the binding response UC_RSP, device A can be roughly time-synchronized with device B by replacing the time of device A with the time of device B that received it.

[0166] [5] At a predetermined timing, the first information communication device 1 broadcasts synchronization information according to the node order and time synchronization characteristics, and starts time synchronization with the virtual clock determined by the virtual clock network state (step S405). At this time, it receives only synchronization information with the virtual clock network identifier of its own network and performs time synchronization.

[0167] [6] The representative node generates primary coupling information from the virtual clock network state, and starts repeatedly broadcasting the coupling information MC at predetermined timing and intervals (step S406), thereby completing the procedure.

[0168] [7] Through the above process, all the information communication devices 1 can switch their operation and role as nodes connected to the virtual clock network that has been formed, and one virtual clock network can be generated or updated from two devices.

[0169] (Combining a virtual clock network with a single device) This section explains the case where multiple virtual clock networks and multiple single device CLs are connected to a synchronization network and simultaneously attempt to join an existing or new virtual clock network. Each virtual clock network can distinguish from other virtual clock networks and connect to the same synchronization network by controlling the communication of synchronization information using a virtual clock network identifier.

[0170] By having the selected representative node operate in the same role as the single device CLs, the virtual clock network can join existing or new virtual clock networks using the same processing procedure as for joining single device CLs, as described above. That is, the representative node broadcasts and sends / receives joining information MC, a joining request UC_REQ, and a joining response UC_RSP. The information and processing specific to joining with a virtual clock network are explained below.

[0171] In the primary connection information of the representative node, the virtual clock network identifier is the virtual clock network identifier of the virtual clock network state, and may be the communication address of the representative node. Also, the number of nodes is the number of nodes in the virtual clock network. The network set identifier is common within the virtual clock network, so it is the network set identifier of the representative node.

[0172] Time reliability is the logical sum of the time reliability in the node list. In other words, if even one node has time reliability, the virtual clock network also has time reliability. Time dependency can also be the logical product of the time dependency in the node list. In other words, if even one node does not have time dependency, the virtual clock network may also not have time dependency. The minimum time L that causes a time difference g is the L in the node list g It may be the average value or the minimum value.

[0173] The primary connection conditions of the primary node are the same as those of single device CLs. The secondary connection information of the primary node is a subset of the primary connection information of the primary node. The secondary connection conditions of the primary node are the same as those of single device CLs, including the connection function. In order to make the virtual clock network the connection target, the virtual clock network formation process is partially extended.

[0174] The virtual clock network stops time synchronization with the virtual clock. The single device CLs updates the node list of its own virtual clock network state to include all elements of the node list in the virtual clock network state received from the representative node. The representative node updates the node list of its own virtual clock network state to include primary coupling information including the communication address of the received single device CLs.

[0175] In a virtual clock network, the representative node distributes and shares the updated virtual clock network state to other nodes. When the virtual clock network synchronizes time with a single device CLs, the representative node calculates the time difference between the time of the single device CLs and the time of its own device CLa, distributes this time difference to other nodes, and the other nodes correct this time difference.

[0176] In this way, the extended virtual clock network formation process allows all nodes of the virtual clock network and single devices CLs to switch their operation and role as nodes connected to a given or newly formed virtual clock network.

[0177] (Connection between virtual clock networks) This section explains the case where multiple virtual clock networks connected to a synchronization network attempt to be connected at the same time. The representative node of each network can connect a virtual clock network to another virtual clock network using the same procedure as connecting single device CLs. The connection between virtual clock networks is the same as connecting a virtual clock network to a single device CL, but the virtual clock network formation process is partially expanded as follows.

[0178] First, one representative node A updates the node list of its own state to include all elements of the node list in the virtual clock network state received from the other representative node B. Furthermore, representative node B updates the node list of its own state to include all elements of the node list in the virtual clock network state received from representative node A.

[0179] When virtual clock network A synchronizes with virtual clock network B, representative node A calculates the time difference between the time of representative node B and the time of its own device CLa, distributes this time difference to other nodes in virtual clock network A, and the other nodes correct this time difference.

[0180] This extended virtual clock network formation process allows all nodes of virtual clock network A to reconnect to virtual clock network B, and virtual clock network A to be integrated into virtual clock network B.

[0181] (separation from virtual clock network) The procedure for separating a partial virtual clock network or an information communication device 1 from a virtual clock network will be described below. Factors that necessitate such separation include a separation request and a fault detection. When the separation receiving unit 713 receives separation information such as a separation request or a fault detection, the virtual clock network forming unit 712 deletes the node to be separated, reconstructs the virtual clock network state, and forms a new virtual clock network.

[0182] A separation request occurs, for example, when inspecting equipment such as the information communication device 1, when the power is turned off, or when a predetermined time has passed since a cable was disconnected. Separation requests include external separation requests input from outside the virtual clock network and internal separation requests generated within a virtual clock network node. An external separation request may be the receipt of separation request information via communication, or an event input to a user interface provided in a node device, such as pressing a button. An internal separation request may be the expiration of a predetermined period or the arrival of a predetermined time, or may be the joining or separation of a device that meets predetermined conditions from the virtual clock network.

[0183] Each separation request includes a separation node list set that identifies the nodes to be separated. The separation node list set is a collection of one or more separation node lists. The separation node list is a collection of one or more separation node identifiers. The separation node identifier may be the communication address of the node to be separated, or may be information that can uniquely identify the node.

[0184] The separated node list may include information such as separation type, network set identifier, and time synchronization operation. The separation type indicates whether the node will operate as a single device CLs after separation or whether a new virtual clock network will be formed with the node set in each separated node list. The network set identifier is set to a different network set identifier so that the node will not be reunited with the original virtual clock network after separation. The time synchronization operation indicates whether time synchronization after separation is enabled or disabled.

[0185] The separation node list set is shared within the virtual clock network. When a virtual clock network receives a separation request, it stops time synchronization with the virtual clock, excludes the nodes to be separated from the separation node list set, reconstructs the virtual clock network state, and forms a new virtual clock network. The nodes to be separated either form a new virtual clock network or switch their operation to become single devices CLs according to the separation node list.

[0186] Fault detection includes communication disruption and degradation of synchronization accuracy. Communication disruption is the detection of a state in which synchronization information is not received from a node for a predetermined period of time. Degradation of synchronization accuracy is the detection of a state in which the time difference or propagation time of a specific node exceeds a predetermined range or fluctuates beyond a predetermined range during time synchronization between nodes in the time synchronization process with the virtual clock.

[0187] In either case of fault detection, the node identifier determined to be faulty is added to a fault list. This identifier may be the communication address of the node or any other information that can uniquely identify the node. The fault list is shared within the virtual clock network.

[0188] The virtual clock network stops sending and receiving synchronization information to and from the nodes included in the fault list, removes the nodes, reconstructs the virtual clock network state, and forms a new virtual clock network. The representative node of the new virtual clock network may send all or part of the fault list to the information communication device 1 that has been determined to be faulty.

[0189] The information communication device 1 that has been determined to be faulty can know that it has been isolated from the virtual clock network by receiving the fault list or by not receiving synchronization information from the virtual clock network for a predetermined period of time.

[0190] The fault list can be referenced via a user interface of the node device and may be updatable. If the fault list is referenceable, it is possible to know which devices have been determined to be faulty and isolated from the virtual clock network. If the fault list is updatable, it is possible to rejoin a desired isolated information communication device 1 to the virtual clock network by deleting the information communication device 1 from the fault list.

[0191] Through the above process, all the information communication devices 1 can autonomously connect and disconnect to form a virtual clock network.

[0192] [effect] (1) This embodiment is an information communication system in which communication units 10 of a plurality of information communication devices 1 communicate information according to the time of a clock 20 that each device has, and each information communication device 1 includes a coupling information storage unit 702 that stores coupling information received by the communication unit 10 and including the communication address of another device CLb that is another information communication device 1, a primary coupling condition determination unit 703 that determines whether or not the other device CLb satisfies a primary coupling condition for forming a virtual clock network based on the coupling information, a coupling request transmission unit 704 that transmits a coupling request including the communication address of its own device CLa that is its own information communication device 1 to the other device CLb that is determined to satisfy the primary coupling condition, a secondary coupling condition determination unit 705 that determines whether or not the own device CLa and the other device CLb satisfy a secondary coupling condition for forming a virtual clock network based on the coupling request received from the own device CLa, and a coupling request that is determined to satisfy the secondary coupling condition, and a coupling request list. a binding candidate determination unit 707 that refers to the binding request in the binding request list and determines a binding candidate that is its own device CLa having a communication address that is uniquely associated with the communication address of the other device CLb; a binding response transmission unit 708 that transmits a binding response including the communication address of the other device CLb to the binding candidate its own device CLa; a binding response storage unit 709 that stores the binding responses received from the other device CLb as a binding response list; a binding determination unit 710 that refers to the binding response list and determines that the information communication device 1 that has the same transmission source as the other device CLb that is the destination of the binding request has been joined to the virtual clock network; a network state generation unit 711 that generates a virtual clock network state that represents the characteristics of the virtual clock network to be formed with the other device CLb that has been judged to have been joined; and a virtual clock network formation unit 712 that forms a virtual clock network with the other device that has been judged to have been joined based on the virtual clock network state.

[0193] The communication unit 10 is a local device CLa that communicates information with other devices CLb that are other multiple information communication devices 1, and the information communication device 1 communicates information according to a clock 20 that the local device CLa has, and includes a coupling information storage unit 702 that stores coupling information including a communication address of the other devices CLb received by the communication unit 10, a primary coupling condition determination unit 703 that determines whether the other devices CLb satisfy a primary coupling condition for forming a virtual clock network based on the coupling information, a coupling request transmission unit 704 that transmits a coupling request including the communication address of the local device CLa that is the information communication device 1 itself to the other devices CLb that are determined to satisfy the primary coupling condition, and The information communication device has a connection response storage unit 709 that, when receiving a connection response including the communication address of a connection candidate determined by another device CLb, which is another information communication device 1, stores the received connection response as a connection response list; a connection determination unit that refers to the connection response list and determines that an information communication device 1 having the same source as the other device CLb, which is the destination of the connection request, has been connected to the virtual clock network; a network state generation unit 711 that generates a virtual clock network state that represents the characteristics of the virtual clock network to be formed with the other device CLb that has been determined to have been connected; and a virtual clock network formation unit 712 that forms a virtual clock network with the other device CLb that has been determined to have been connected based on the virtual clock network state.

[0194] The device has a secondary connection condition determination unit 705 that determines whether or not another device CLb satisfies the secondary connection condition for forming a virtual clock network based on a connection request transmitted from its own device CLa, a connection request storage unit 706 that stores connection requests that have been determined to satisfy the secondary connection condition as a connection request list, a connection candidate determination unit 707 that refers to the connection requests in the connection request list and determines a connection candidate that is its own device CLa having a communication address that is uniquely associated with the communication address of the other device CLb, and a connection response transmission unit 708 that transmits a connection response including the communication address of the other device CLb to its own device CLa, which is the connection candidate.

[0195] Therefore, without setting information about the information and communication system in advance, a virtual clock network can be formed by sending and receiving connection information, connection requests, and connection responses, through primary connection condition determination, secondary connection condition determination, connection candidate determination, connection determination, and network state generation.

[0196] (2) The coupling information includes time reliability as primary coupling information for determining the primary coupling condition, and the primary coupling condition determination unit 703 determines that the primary coupling condition is satisfied if either the other device CLb or its own device CLa has time reliability. Furthermore, the virtual clock network formation unit 712 synchronizes time with the information communication device 1 with time reliability. Therefore, a stable virtual clock network can be formed in accordance with the information communication device 1 with time reliability.

[0197] (3) Either or both of the own device CLa and the other device CLb are representative nodes of the virtual clock network. Therefore, in the same way as connecting single devices CLs, it is possible to connect virtual clock networks to single devices CLs and to other virtual clock networks.

[0198] (4) This embodiment includes a separation reception unit 713 that, when separation information about any one of the information communication devices 1 is received, causes the virtual clock network formation unit 712 to re-form the virtual clock network, excluding the relevant information communication device 1. Therefore, in the case of a separation request or fault detection, it is possible to separate a specific information communication device 1 and re-form the virtual clock network.

[0199] (5) The joining candidate determination unit 707 determines the communication address of the joining candidate that has the closest communication address value to the communication address value of the own device CLa based on the communication address value of the other device CLb in the joining request list, which is an integer value, and the communication address value of the own device CLa, which is an integer value. Also, the joining candidate determination unit 707 selects the closest communication address value according to chance and sets it as the communication address of the joining candidate.

[0200] Therefore, the communication addresses of the joining candidates can be determined quickly. More specifically, according to this embodiment, if the maximum communication address value is A, the communication addresses of the joining candidates can be obtained by applying the update function f(x) at most [log2A] times. Furthermore, even if multiple information communication devices 1 operate simultaneously to obtain joining candidates, at least two information communication devices 1 can be uniquely associated with each other as joining candidates. Furthermore, since a set of multiple information communication devices 1 is independently and parallelly uniquely associated with each other as joining candidates, there is an advantage in that a virtual clock network can be formed quickly.

[0201] (5) This embodiment is an information communication system 100 in which a communication unit 10 of a plurality of information communication devices 1 communicates information according to the time of a clock 20 that each device has, and includes a communication control unit 73 that causes the communication unit 10 to transmit and receive synchronization information within a predetermined time period that can be considered as a constant time difference between the information communication devices 1, a time acquisition unit 76 that acquires the transmission time of the synchronization information from one of the information communication devices 1, which is the own device CLa, the reception time of the synchronization information transmitted from the own device CLa by another device CLb that is another information communication device 1 other than the own device CLa, the transmission time of the synchronization information from all the other devices CLb, and the reception time of the synchronization information transmitted from all the other devices CLb by the own device CLa, and a time acquisition unit 77 that acquires the transmission time of the synchronization information from one of the information communication devices 1, which is the own device CLa, the reception time of the synchronization information transmitted from all the other devices CLb by the own device CLa, and a time acquisition unit 78 that acquires the transmission time of the synchronization information from one of the information communication devices 1, which is the own device CLa, the reception time of the synchronization information transmitted from all the other devices CLb by the own device CLa, and a time acquisition unit 79 ... The information communication device 1 includes a time difference calculation unit 77 that calculates the time difference between the clock 20 of the device itself CLa and the clock 20 of all other devices CLb based on the transmission time of the device itself CLa, the reception time of the device itself CLa, the transmission times of all other devices CLb, and the reception times of all other devices CLb acquired by the acquisition unit 76; a virtual time difference calculation unit 78 that calculates a virtual time difference, which is the time difference between the clock 20 of the device itself CLa and a virtual clock that is a virtual clock that can be considered as a common time source for all information communication devices 1, based on the time difference between the clock 20 of the device itself CLa and all clocks 20; and a synchronization control unit 79 that time-synchronizes the clock 20 of the device itself CLa with the virtual clock based on the virtual time difference calculated by the time difference calculation unit 77.

[0202] In this way, by assuming a virtual clock based on the time difference between the clocks 20 of the own device CLa and other device CLb, fluctuations in the propagation time of information communication can be absorbed and synchronization control with reduced errors can be achieved by information communication only between the information communication devices 1, without using a reference clock such as GMC or a relay device such as BC or TC. By having the communication units 10 transmit and receive synchronization information within a predetermined time period in which the time difference between the information communication devices 1 can be considered constant, synchronization control can be achieved without causing time difference errors due to frequency deviation fluctuations and propagation time fluctuations of the clocks 20. As described above, in this embodiment, the average value of the time difference from the clock 20 of the other device CLb is taken as the time difference between the clock 20 of the own device CLa and the virtual clock.

[0203] (6) The communication units 10 of the own device CLa and the other devices CLb are connected via a complete network, so that it is possible to calculate the time difference with all other devices CLb other than the own device CLa.

[0204] (7) Communication control units 73 of local device CLa and other device CLb cause communication units 10 to simultaneously transmit synchronization information within a predetermined time period, thereby enabling time acquisition unit 76 to efficiently acquire the four transmission and reception times.

[0205] (8) The communication unit 10 transmits and receives synchronization information while maintaining an equal relationship between the absolute value of the propagation time deviation at the timing of the own device CLa and the absolute value of the propagation time deviation at the timing of the other device CLb. This makes it possible to achieve an expected value of 0 for the synchronization phase difference with the virtual clock, i.e., time synchronization centered on the virtual clock.

[0206] [Variations] (1) As described above, it is preferable that the form of the synchronization network NE is a complete network. However, the physical form does not need to be a complete network; even a star-shaped synchronization network NE centered on one hub can be used as long as it can realize a complete network in the communication mode of synchronization information. Note that even if the synchronization network NE does not form a complete network, it is possible to synchronize with the virtual clock v using this principle. However, a synchronization error occurs because equation (16) obtained for each information communication device 1 is not the same. Note that even if one of the information communication devices 1 fails, the current time synchronization can be maintained by degenerating the synchronization network NE and configuring a complete network.

[0207] (2) The information communication device 1 and the synchronization network NE to which the virtual clock network is connected are not limited to the above-mentioned embodiments, and may be a PTP system having a reference clock.

[0208] [Other embodiments] The present invention is not limited to the above-described embodiment, and various inventions can be realized by modifying the components within the scope of the gist of the present invention. Furthermore, various inventions can be realized by appropriately combining the multiple components disclosed in the above-described embodiment. [Explanation of symbols]

[0209] 1. Information and communication devices 10. Communications Department 11 Transmitter 12 Receiver 13 Transmission timing detection unit 14 Reception timing detection unit 20 Clock 30 Clock 50 Storage section 60 external interfaces 70 Control Unit 71 Main control unit 72 Sending and receiving data I / F 73 Communication control section 74 Scheduler 75 Time Recording Unit 76 Time acquisition part 77 Time difference calculation unit 78 Virtual time difference calculation unit 79 Synchronization control section 100 Information and Communication Systems 701 Combined information transmission unit 702 Combined information storage unit 703 Primary connection condition judgment part 704 Binding Request Sending Unit 705 Secondary connection condition judgment part 706 Join request storage 707 Combined candidate determination unit 708 Binding Response Sending Unit 709 Combined Response Memory Unit 710 Connection determination section 711 Network Status Generation Unit 712 Virtual Clock Network Formation Unit 713 Separate Reception Department

Claims

1. An information and communication system in which communication units of a plurality of information and communication devices communicate information according to the time of their respective clocks, Each information communication device: a connection information storage unit that stores connection information including a communication address of another device that is another information communication device received by the communication unit; a primary connection condition determination unit that determines whether or not the other device satisfies a primary connection condition for forming a virtual clock network based on the connection information; a binding request sending unit that sends a binding request including a communication address of the own device, which is the information communication device, to the other device that is determined to satisfy the primary binding condition; a secondary connection condition determination unit that determines whether or not the device itself and the other device satisfy a secondary connection condition for forming a virtual clock network based on a connection request received from the device itself; a join request storage unit that stores the join requests that are determined to satisfy the secondary join condition as a join request list; a merge candidate determination unit that refers to the merge request in the merge request list and determines a merge candidate that is the device itself having a communication address that is uniquely associated with the communication address of the other device; a binding response transmitting unit that transmits a binding response including a communication address of another device to the binding candidate device; a binding response storage unit that stores the binding responses received from other devices as a binding response list; a connection determination unit that refers to the connection response list and determines that an information communication device that has the same source as another device that is the destination of the connection request has been connected to the virtual clock network; a network state generation unit that generates a virtual clock network state that represents the characteristics of a virtual clock network formed between the other device that has been determined to be connected; a virtual clock network forming unit that forms a virtual clock network with other devices that are determined to be connected based on the virtual clock network state; An information and communication system comprising:

2. The information communication system according to claim 1, characterized in that the coupling information includes time reliability as primary coupling information for determining the primary coupling condition, and the primary coupling condition determination unit determines that the primary coupling condition is satisfied if either the other device or the device itself has time reliability.

3. 2. The information communication system according to claim 1, wherein the virtual clock network forming unit synchronizes time with information communication devices with reliable time.

4. 2. The information communication system according to claim 1, wherein one or both of the local device and the other device is a representative node of the virtual clock network.

5. The information and communication system according to claim 1, further comprising a separation reception unit that, when separation information about any one of the information and communication devices is received, causes the virtual clock network formation unit to re-form the virtual clock network, excluding the information and communication device.

6. The information communication system described in claim 1, characterized in that the connection candidate determination unit determines the communication address of the connection candidate to be the communication address of the communication address value of the device itself, based on the communication address value of the other device in the connection request list, which is an integer value, and the communication address value of the device itself, which is an integer value.

7. 7. An information communication system according to claim 6, wherein the nearest communication address value is selected according to chance and is used as the communication address of the joining candidate.

8. a communication control unit that causes the communication unit to transmit and receive synchronization information within a predetermined time period that can be considered as a constant time difference between the information communication devices; a time acquisition unit that acquires a transmission time of the synchronization information from a local device that is any one of the information communication devices, a reception time of the synchronization information transmitted from the local device received by another device that is an information communication device other than the local device, a transmission time of the synchronization information from all the other devices, and a reception time of the synchronization information transmitted from all the other devices received by the local device; a time difference calculation unit that calculates a time difference between the clock of the own device and the clocks of all the other devices based on the transmission time of the own device, the reception time of the own device, the transmission times of all the other devices, and the reception times of all the other devices that are acquired by the time acquisition unit; a virtual time difference calculation unit that calculates a virtual time difference between the clock of the local device and a virtual clock that is a virtual clock that can be considered as a common time source for all of the information communication devices, based on the time difference between the clock of the local device and all of the clocks; a synchronization control unit that synchronizes the clock of the device with a virtual clock based on the virtual time difference calculated by the virtual time difference calculation unit; 2. The information communication system according to claim 1, comprising:

9. The communication unit is a device that communicates information with other devices that are other multiple information communication devices, and the communication unit communicates information according to a clock that the device has, a connection information storage unit that stores connection information including a communication address of another device received by the communication unit; a primary connection condition determination unit that determines whether or not the other device satisfies a primary connection condition for forming a virtual clock network based on the connection information; a binding request sending unit that sends a binding request including a communication address of the own device, which is the information communication device, to the other device that is determined to satisfy the primary binding condition; a binding response storage unit configured to store, when receiving a binding response including a communication address of a binding candidate determined by another device that is another information communication device in response to the binding request, the received binding response as a binding response list; a connection determination unit that refers to the connection response list and determines that another device that has the same source as the other device that is the destination of the connection request has been connected to the virtual clock network; a network state generation unit that generates a virtual clock network state representing the characteristics of the virtual clock network formed between the other device that has been determined to be connected; a virtual clock network forming unit that forms a virtual clock network with other devices that are determined to be connected based on the virtual clock network state; An information communication device comprising:

10. a secondary connection condition determination unit that determines whether or not another device satisfies a secondary connection condition for forming a virtual clock network based on a connection request transmitted from the information communication device according to claim 9; a join request storage unit that stores join requests that are determined to satisfy the secondary join condition as a join request list; a merge candidate determination unit that refers to the merge request in the merge request list and determines a merge candidate that is the device itself having a communication address that is uniquely associated with the communication address of the other device; a binding response transmitting unit that transmits a binding response including a communication address of another device to the binding candidate device; An information communication device comprising:

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