JP2016225714A - Signal transmission device for delay measurement, delay measuring system, signal transmission method for delay measurement, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the consumption of communication resources when a transmission delay time is measured.SOLUTION: A signal transmission device for delay measurement comprises: a reception unit for receiving a signal; a transmission signal generation unit for generating a transmission signal that has stored reception time information indicating reception time when the reception unit received the signal; a differential time calculation unit for calculating a differential time obtained by subtracting the reception time indicated by the reception time information from present time; a differential time reflection unit for storing information indicating the differential time calculated by the differential time calculation unit in the transmission signal generated by the transmission signal generation unit; and a transmission unit for transmitting the transmission signal in which the differential time reflection unit has stored the information indicating the differential time.SELECTED DRAWING: Figure 6

Description

The present invention relates to a delay measurement signal transmission apparatus, a delay measurement system, a delay measurement signal transmission method, and a program.

IEEE 1588 (PTP) is a protocol for synchronizing the time between devices, and Peer-to-Peer (P2P) is a PTP connection form.
In P2P, a transmission delay between each device (PTP-compatible device) that is positioned on the uplink side (Master side) is measured in a mechanism called a Peer Delay mechanism. The transmission delay here is the time required for the communication signal to pass through the transmission path (that is, the time from the transmission side device transmitting the communication signal to the reception side device).

  In the Peer Delay mechanism, a method in which an uplink side device transmits a frame called Pdelay_Resp and a frame called Pdelay_Resp_Follow_Up with respect to a frame called Pdelay_Req from a downlink side device has been put into practical use (Patent Literature). 1 and non-patent document 1). The device on the uplink side notifies the time when Pdelay_Req is received in Pdelay_Resp. Also, Pdelay_Resp_Follow_Up notifies information for determining the delay time in the uplink side device, such as the time when Pdelay_Resp was transmitted.

US Patent Application Publication No. 2012/0275501

Ron Cohen, “Precision Time Protocol IEEE1588v2”, [online], 2007, TICTOC BOF Prague 2007, [April 1, 2015 search], Internet (URL: http://www.ietf.org/proceedings/68 /slides/tictoc-4/tictoc-4.ppt)

  In the method of transmitting and receiving Pdelay_Resp and Pdelay_Resp_Follow_Up, communication resources are consumed in that two signals are transmitted and received.

  The present invention provides a signal transmission device for delay measurement, a delay measurement system, a signal transmission method for delay measurement, and a program capable of reducing the consumption of communication resources when measuring a transmission delay time.

  According to the first aspect of the present invention, the delay measurement signal transmission apparatus includes a reception unit that receives a signal, and a transmission signal that stores reception time information indicating a reception time at which the reception unit receives the signal. A transmission signal generation unit to generate, a difference time calculation unit to calculate a difference time obtained by subtracting the reception time indicated by the reception time information from a current time, and the transmission signal generated by the transmission signal generation unit, A difference time reflection unit that stores information indicating the difference time calculated by the difference time calculation unit; and a transmission unit that transmits the transmission signal in which the difference time reflection unit stores information indicating the difference time. Prepare.

  The difference time calculation unit may acquire the current time and calculate the difference time after the transmission destination of the transmission signal is determined.

  The transmission unit transmits the transmission signal in which the difference time reflecting unit stores information indicating the difference time, and the transmission unit stores information indicating the reception time. You may make it provide the switch part which switches the transmission signal and the 2nd transmission process which transmits the 2nd transmission signal in which the information which shows the transmission time of the said 1st transmission signal was stored.

  According to the second aspect of the present invention, the delay measurement system transmits a request signal for requesting transmission of a delay measurement signal, and calculates a delay time of communication based on the obtained delay measurement signal. A signal measurement device for delay, and a signal transmission device for delay measurement that transmits the signal for delay measurement in response to the request signal, the signal transmission device for delay measurement includes a receiving unit that receives the request signal; A transmission signal generation unit that generates a transmission signal that stores reception time information indicating a reception time when the reception unit has received the request signal, and a differential time obtained by subtracting the reception time indicated by the reception time information from a current time The delay time calculation unit generates the delay measurement signal by storing information indicating the difference time calculated by the difference time calculation unit in the transmission signal generated by the difference time calculation unit and the transmission signal generation unit. You It comprises a difference time reflecting unit, and a transmission unit that transmits the delay measurement signal.

  According to a third aspect of the present invention, in the delay measurement signal transmission method, the delay measurement signal transmission apparatus receives the signal, and the delay measurement signal transmission apparatus performs the reception step in the reception step. A transmission signal generation step for generating a transmission signal storing reception time information indicating a reception time when the signal is received; and the delay measurement signal transmission device subtracts the reception time indicated by the reception time information from a current time. A difference time calculation step for calculating the difference time, and the delay measurement signal transmission apparatus adds the difference time calculated in the difference time calculation step to the transmission signal generated in the transmission signal generation step. A difference reflecting step for storing the information indicating, and the delay measurement signal transmitting apparatus transmitting the transmission signal storing the information indicating the difference time in the difference reflecting step. Having a transmission step of, a.

  According to the fourth aspect of the present invention, the program stores, in a computer that controls the signal transmission device for delay measurement, a reception step of receiving a signal, and a reception time indicating a reception time of receiving the signal in the reception step. A transmission signal generation step for generating a transmission signal storing information, a difference time calculation step for calculating a difference time obtained by subtracting the reception time indicated by the reception time information from a current time, and a transmission signal generation step. A difference reflecting step for storing information indicating the difference time calculated in the difference time calculating step and a information for indicating the difference time in the difference reflecting step. And a transmission step for transmitting a signal.

  According to the present invention, it is possible to reduce the consumption of communication resources when measuring the transmission delay time.

It is a schematic block diagram which shows the apparatus structure of the delay measurement system in one Embodiment of this invention. It is explanatory drawing which shows the example of the signal transmission / reception between the signal transmission apparatus for delay measurement and the signal request apparatus for delay measurement in the embodiment. It is explanatory drawing which shows another example of the signal transmission / reception between the signal transmission apparatus for delay measurement and the signal request apparatus for delay measurement in the embodiment. It is a schematic block diagram which shows the example of arrangement | positioning of the apparatus which performs time synchronization in the same embodiment. It is explanatory drawing which shows the example of the process sequence which a master apparatus and a slave apparatus synchronize time in the same embodiment. It is a schematic block diagram which shows the function structure of the signal transmission apparatus for delay measurement in the embodiment. It is explanatory drawing which shows the example of the hierarchical structure of the communication protocol of the signal transmission apparatus for delay measurement in the embodiment. It is explanatory drawing which shows the example of the process sequence which the signal transmission apparatus for delay measurements in the embodiment performs a transmission process once. It is explanatory drawing which shows the example of the process sequence which the signal transmission apparatus for delay measurement in the embodiment performs a transmission process twice. It is a flowchart which shows the procedure of the process which the signal transmission apparatus for delay measurements in the embodiment responds to Pdelay_Req. It is a schematic block diagram which shows the function structure of the master apparatus in the modification of this embodiment. It is explanatory drawing which shows the example of the process sequence which a master apparatus transmits Sync and Sync_Follow_Up in the modification.

Hereinafter, although embodiment of this invention is described, the following embodiment does not limit the invention concerning a claim. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.
FIG. 1 is a schematic configuration diagram showing a device configuration of a delay measurement system according to an embodiment of the present invention. In FIG. 1, the delay measurement system 10 includes a delay measurement signal transmission device 11 and a delay measurement signal requesting device 12.

  Hereinafter, a case where the delay measurement signal transmission device 11 and the delay measurement signal request device 12 calculate the transmission delay time in accordance with the IEEE 1588v2 specification will be described as an example, but the present invention is not limited thereto. For example, in IEEE 1588v2, the delay measurement signal transmission device 11 is the device closest to the uplink side of the delay measurement signal request device 12 (PTP-compatible device), but is not limited thereto, and the delay measurement signal transmission device 11 is not limited thereto. The delay measurement signal requesting device 12 may be located on the downlink side, or a relay device may be provided between the delay measurement signal transmission device 11 and the delay measurement signal requesting device 12.

The delay measurement signal requesting device 12 obtains the transmission delay of the communication path with the delay measurement signal transmitting device 11. Specifically, the delay measurement signal requesting device 12 transmits a request signal for requesting transmission of the delay measurement signal to the delay measurement signal transmitting device 11. Then, the delay measurement signal requesting device 12 obtains a communication delay time based on the obtained delay measurement signal.
The delay measurement signal transmission device 11 generates and transmits a delay measurement signal in response to the request signal from the delay measurement signal request device 12.

FIG. 2 is an explanatory diagram illustrating an example of signal transmission / reception between the delay measurement signal transmission device 11 and the delay measurement signal requesting device 12. In the example of the figure, the delay measurement signal requesting device 12 transmits Pdelay_Req to the delay measurement signal transmitting device 11, and the delay measurement signal transmitting device 11 transmits Pdelay_Resp to the delay measurement signal requesting device 12. Pdelay_Req corresponds to an example of a request signal. Pdelay_Resp corresponds to an example of a delay measurement signal.
The time when the delay measurement signal requesting device 12 transmits Pdelay_Req is indicated by T1, and the time when the delay measurement signal transmitting device 11 receives Pdelay_Req is indicated by T2. In addition, the time when the delay measurement signal transmission device 11 transmits Pdelay_Resp is indicated by T3, and the time when the delay measurement signal requesting device 12 receives Pdelay_Resp is indicated by T4.

  The transmission delay time of the communication path from the delay measurement signal requesting device 12 to the delay measurement signal transmitting device 11 is indicated by T2-T1. Further, the transmission delay time of the communication path from the delay measurement signal transmitting device 11 to the delay measurement signal requesting device 12 is indicated by T4-T3. When the communication path from the delay measurement signal requesting device 12 to the delay measurement signal transmitting device 11 and the communication path from the delay measurement signal transmitting device 11 to the delay measurement signal requesting device 12 are the same, the delay measurement signal transmission device 11 The transmission delay time Ttr of the communication path between the signal transmission device 11 and the delay measurement signal requesting device 12 is represented by the equation (1).

Therefore, the delay measurement signal transmission device 11 stores and transmits information indicating T3-T2 in Pdelay_Resp. Then, the delay measurement signal requesting device 12 holds (stores) the time T1 and the time T4, reads T3-T2 from Pdelay_Resp, and calculates the transmission delay time Ttr based on Expression (1). In the following, information indicating time is also simply expressed as time. For example, storing information indicating time is also simply referred to as storing time. Similarly, information indicating time is also simply expressed as time.
In addition, the delay measurement signal transmission device 11 can also cope with a method of transmitting a response signal defined in IEEE 1588v2 twice. This point will be described with reference to FIG.

  FIG. 3 is an explanatory diagram showing another example of signal transmission / reception between the delay measurement signal transmission device 11 and the delay measurement signal requesting device 12. 2, in the example of FIG. 3, the delay measurement signal requesting device 12 transmits Pdelay_Req to the delay measurement signal transmitting device 11, and the delay measurement signal transmitting device 11 transmits to the delay measurement signal requesting device 12. Pdelay_Resp is transmitted. Times T1, T2, T3, and T4 are the same as those in FIG.

  On the other hand, unlike the case of FIG. 2, in the example of FIG. 3, the delay measurement signal transmission device 11 transmits Pdelay_Resp_Follow_Up to the delay measurement signal request device 12 in addition to Pdelay_Resp. Pdelay_Resp_Follow_Up is also expressed as Follow_Up. In the example of FIG. 2, the delay measurement signal transmission device 11 stores T3-T2 in Pdelay_Resp and transmits it. In the example of FIG. 3, the delay measurement signal transmission device 11 stores time T2 in Pdelay_Resp. Then send. Also, the delay measurement signal transmission device 11 stores the time T3 in Pdelay_Resp_Follow_Up and transmits the result.

In the example of FIG. 3, the delay measurement signal requesting device 12 holds (stores) time T1 and time T4, and reads time T2 and time T3 from Pdelay_Resp and Pdelay_Resp_Follow_Up, respectively. Then, the delay measurement signal requesting device 12 calculates the transmission delay time Ttr by substituting the obtained times T1, T2, T3, and T4 into the equation (1).
In this way, even when the delay measurement signal requesting device 12 does not support the method of transmitting only Pdelay_Resp by transmitting the Pdelay_Resp and the Pdelay_Resp_Follow_Up to the Pdelay_Req, the delay measurement signal transmitting device 11 transmits the Pdelay_Resp. The signal requesting device 12 can determine the transmission delay time Ttr.

  Note that the delay measurement signal transmission apparatus 11 may store T3-T2 in Pdelay_Resp_Follow_Up and transmit it. In this case, the delay measurement signal requesting device 12 holds (stores) time T1 and time T4, reads T3-T2 from Pdelay_Resp_Follow_Up, and calculates the transmission delay time Ttr based on Expression (1).

Next, an example of an application scene of the transmission delay time measurement method described with reference to FIGS. 1 to 3 will be described with reference to FIGS. 4 and 5.
FIG. 4 is a schematic configuration diagram illustrating an arrangement example of apparatuses that perform time synchronization. In the example of FIG. 1, the time synchronization system 20 includes a master device 21, a transparent clock (TC) device 22, and a slave device 23. The master device 21 and the slave device 23 are communicatively connected via a transparent clock device 22. The transparent clock device 22 is configured using, for example, a switch (Switch, S / W).

FIG. 5 is an explanatory diagram illustrating an example of a processing procedure in which the master device 21 and the slave device 23 perform time synchronization.
In the process of FIG. 8, the slave device 23 measures the transmission delay time with the transparent clock device 22 in advance (sequence S21). In this case, the transparent clock device 22 corresponds to an example of the delay measurement signal transmission device 11, and the slave device 23 corresponds to an example of the delay measurement signal request device 12. The transparent clock device 22 and the slave device 23 may measure the transmission delay time by the method shown in FIG. 2, or may measure the transmission delay time by the method shown in FIG.

  Further, the transparent clock device 22 measures a transmission delay time with the master device 21 in advance (sequence S22). In this case, the master device 21 corresponds to an example of the delay measurement signal transmission device 11, and the transparent clock device 22 corresponds to an example of the delay measurement signal request device 12. The master device 21 and the transparent clock device 22 may measure the transmission delay time by the method shown in FIG. 2, or may measure the transmission delay time by the method shown in FIG.

After the sequences S21 and S22, the master device 21 transmits Sync to the slave device 23, and time synchronization is performed between the master device 21 and the slave device 23 (sequence S23). When the master device 21 transmits the Sync, the master device 21 stores the transmission time of the Sync in the Sync.
When the transparent clock device 22 relays the Sync, the transparent clock device 22 stores the delay time in the Sync (sequence S24). Specifically, the transparent clock device 22 stores the transmission delay time obtained in the sequence S22 and the delay time inside the transparent clock device 22 stored in advance in Sync. The internal delay time of the transparent clock device 22 here is a time required from when the transparent clock device 22 receives the Sync to when the Sync is transmitted. When the transparent clock device 22 relays the Sync, the transmission time may be read from the Sync and the delay time may be added. In this case, the transparent clock device 22 adds the transmission delay time obtained in the sequence S22 and the previously stored delay time inside the transparent clock device 22 to the transmission time read from the Sync.
The transparent clock device 22 may rewrite (overwrite) the transmission time stored in the Sync to a time obtained by adding a delay time to the transmission time. Alternatively, the transparent clock device 22 may notify the slave device 23 of the time obtained by adding the delay time to the Sync transmission time using a signal different from the Sync.

The slave device 23 further adds the transmission delay time obtained in the sequence S21 to the delay time stored in the Sync by the transparent clock device 22, and adds the added transmission delay time to the Sync transmission time. The reception time (time T22) is calculated (sequence S25).
Then, the slave device 23 performs a process for correcting the difference between the time of the internal clock when the Sync is received and the time T22 obtained in the sequence S25 on the internal clock, so that the time with the master device 21 is reached. Synchronization is performed (sequence S26).

Next, the configuration of the delay measurement signal transmission apparatus 11 will be described with reference to FIGS. 6 and 7.
FIG. 6 is a schematic block diagram illustrating a functional configuration of the delay measurement signal transmission apparatus 11. As shown in the figure, the delay measurement signal transmission device 11 includes a transmission / reception unit 110, a time processing unit 120, and a protocol processing unit 160. The transmission / reception unit 110 includes a frame reception unit 111 and a frame transmission unit 112. The time processing unit 120 includes a clock unit 121, a frame analysis unit 131, a reception time addition unit 132, an operation analysis unit 141, and a transmission frame time processing unit 150. The transmission frame time processing unit 150 includes a one-time transmission processing unit 151 and a two-time transmission processing unit 154. The one-time transmission processing unit 151 includes a difference time calculation unit 152 and a difference time reflection unit 153. The twice transmission processing unit 154 includes a transmission time storage unit 155 and a transmission time insertion unit 156. The protocol processing unit 160 includes an analysis unit 161 and a frame generation unit 162.

  Further, both the frame reception unit 111 and the frame transmission unit 112 are communicatively connected to the communication network 900. The delay measurement signal transmission device 11 communicates with the delay measurement signal request device 12 (FIG. 1) via the communication network 900. As described above, when complying with the IEEE 1588v2 standard, the delay measurement signal transmission device 11 is a device (PTP compatible) that is positioned closest to the delay measurement signal transmission device 11 on the downlink side (slave side) of the communication network 900. The apparatus) is used as the delay measurement signal requesting apparatus 12, and the signal transmission / reception described with reference to FIG. 2 or the signal transmission / reception described with reference to FIG.

The communication network 900 constitutes a communication path between the delay measurement signal transmitting device 11 and the delay measurement signal requesting device 12. That is, the delay measurement signal transmitting apparatus 11 and the delay measurement signal requesting apparatus 12 communicate via the communication network 900 to measure the transmission delay as described with reference to FIGS.
Note that the delay measurement signal transmission device 11 does not depend on the communication method of the communication network 900. For example, the communication network 900 may be Ethernet (registered trademark), but is not limited thereto. Hereinafter, a case where the delay measurement signal transmission device 11 transmits and receives a frame will be described as an example. However, the format of the signal transmitted and received by the delay measurement signal transmission device 11 is not limited to the frame format.

The frame receiving unit 111 receives a signal transmitted from another device in the form of a frame via the communication network 900. In particular, as shown in FIG. 2 or FIG. 3, the frame reception unit 111 receives Pdelay_Req from the delay measurement signal requesting device 12.
The frame transmission unit 112 transmits a signal to another device via the communication network 900 in the form of a frame. In particular, as illustrated in FIG. 2, the frame transmission unit 112 transmits Pdelay_Resp to the delay measurement signal requesting device 12. In this case, the frame transmission unit 112 transmits the Pdelay_Resp in which the difference time reflection unit 153 stores the difference time (T3-T2 in Expression (1)) between the reception time of Pdelay_Req and the transmission time of Pdelay_Resp. Alternatively, as illustrated in FIG. 3, the frame transmission unit 112 transmits Pdelay_Resp and Pdelay_Resp_Follow_Up to the delay measurement signal requesting device 12.

The time processing unit 120 performs processing related to the reception time of Pdelay_Req and the transmission time of Pdelay_Resp. Specifically, the time processing unit 120 detects the reception time of Pdelay_Req and notifies the protocol processing unit 160 of it. In addition, the time processing unit 120 acquires and stores the transmission time of Pdelay_Resp.
The clock unit 121 is an internal clock of the delay measurement signal transmitter 11 and outputs the current time.
The frame analysis unit 131 analyzes the frame received by the frame reception unit 111. In particular, when the frame analysis unit 131 detects a reception frame (a frame received by the frame reception unit 111), the reception time adding unit 132 starts processing.

The reception time adding unit 132 adds the reception time to Pdelay_Req received by the frame reception unit 111. Specifically, when the frame analysis unit 131 detects a received frame, the reception time adding unit 132 acquires the current time from the clock unit 121 and associates the obtained current time with the frame (Pdelay_Req) as the reception time. To the analysis unit 161.
Various methods can be used as a method in which the reception time adding unit 132 associates Pdelay_Req with the reception time. For example, the reception time adding unit 132 may write the reception time at a predetermined position of Pdelay_Req. Alternatively, the reception time adding unit 132 may add a header or trailer indicating the reception time to the Pdelay_Req.

  The operation analysis unit 141 analyzes the operation (operation command) output by the frame generation unit 162 in association with the frame. In particular, the operation analysis unit 141 corresponds to an example of a switching unit, and switches between a one-time transmission process and a two-time transmission process according to an operation. Specifically, the operation analysis unit 141 selects one transmission process or two transmission processes for each frame output by the frame generation unit 162. Here, the one-time transmission process is a process of transmitting a Pdelay_Resp storing the difference time between the reception time of Pdelay_Req and the transmission time of Pdelay_Resp as described with reference to FIG. In this case, Pdelay_Resp transmitted by the frame transmission unit 112 corresponds to an example of a delay measurement signal. The twice transmission process is a process of transmitting Pdelay_Resp and Pdelay_Resp_Follow_Up as described with reference to FIG. In this case, Pdelay_Resp and Pdelay_Resp_Follow_Up transmitted by the frame transmission unit 112 correspond to examples of the first transmission signal and the second transmission signal, respectively.

The transmission frame time processing unit 150 performs a process of storing information on the transmission time in a transmission frame (a frame transmitted by the frame transmission unit 112).
In the case of a one-time transmission process, the one-time transmission processing unit 151 performs a process of storing a difference time between the reception time of Pdelay_Req and the transmission time of Pdelay_Resp in Pdelay_Resp.

  The difference time calculation unit 152 calculates the difference time between the reception time of Pdelay_Req and the transmission time of Pdelay_Resp. Specifically, the differential time calculation unit 152 reads the reception time of Pdelay_Req stored in Pdelay_Resp. Further, the difference time calculation unit 152 acquires the current time from the clock unit 121 as the transmission time of Pdelay_Resp. Then, the difference time calculation unit 152 calculates a difference time obtained by subtracting the reception time of Pdelay_Req from the current time.

  Here, the difference time calculation unit 152 is provided in the MAC (Media Access Controller) layer and, after completing the ARP (Address Resolution Protocol) processing, acquires the current time and calculates the difference time. The ARP processing here is processing for acquiring a destination MAC address. Therefore, after the transmission destination of Pdelay_Resp is determined, the differential time calculation unit 152 acquires the current time and calculates the differential time.

FIG. 7 is an explanatory diagram illustrating an example of a hierarchical structure of a communication protocol of the delay measurement signal transmission apparatus 11. As shown in the figure, the signal transmission device 11 for delay measurement includes a PHY layer (physical layer), a MAC layer, an IP (Internet Protocol) layer, a UDP (User Datagram Protocol) layer, a PTP (Precision Time) in order from the lower layer. Protocol) layer. The protocol processing unit 160 is provided in an upper layer from the IP layer among these layers. However, in the case of L2-type PTP (PTP over Ethernet, Ethernet is a registered trademark), the IP layer and the UDP layer do not exist, and the PTP layer is directly above the MAC layer. That is, the protocol processing unit 160 may be provided in a layer higher than the MAC layer among these layers.
On the other hand, the time processing unit 120 is provided in the MAC layer. The ARP process is also performed in the MAC layer, and the difference time calculation unit 152 obtains the current time from the clock unit 121 after the ARP process is completed, and calculates the difference time. In the present embodiment, by providing the time processing unit 120 in the MAC layer, delays other than physical delays in hardware do not affect the frame, so that delays can be suppressed. Furthermore, by providing the time processing unit 120 in the MAC layer, additional information such as control information can be attached to the frame, and the frame can be easily controlled.

  In particular, since the time processing unit 120 is provided in the MAC layer, the time difference from when the differential time calculation unit 152 acquires the current time as the transmission time of Pdelay_Resp until the frame transmission unit 112 transmits Pdelay_Resp, The fluctuation of the time required for ARP processing is not included. In this regard, the fluctuation of the difference time calculated by the difference time calculation unit 152 with respect to the actual time from when the frame reception unit 111 receives Pdelay_Req to when the frame transmission unit 112 transmits Pdelay_Resp can be reduced.

The difference time reflection unit 153 stores the difference time calculated by the difference time calculation unit 152 in the Pdelay_Resp generated by the frame generation unit 162. Pdelay_Resp generated by the frame generation unit 162 corresponds to an example of a transmission signal, and Pdelay_Resp after the difference time reflection unit 153 stores the difference time corresponds to an example of a delay measurement signal.
In the case of the two-time transmission process, the twice-transmission processing unit 154 performs a process of storing the transmission time of Pdelay_Resp in Pdelay_Resp_Follow_Up.

  The transmission time storage unit 155 stores the transmission time of Pdelay_Resp. Specifically, when Pdelay_Resp is transmitted in the twice transmission process, the frame generation unit 162 outputs an operation instructing to store the current time in association with Pdelay_Resp. Then, the operation analysis unit 141 stores the current time in the transmission time storage unit 155 according to the operation.

  The transmission time insertion unit 156 inserts the transmission time of Pdelay_Resp stored in the transmission time storage unit 155 into Pdelay_Resp_Follow_Up. Specifically, when transmitting Pdelay_Resp_Follow_Up in the two-time transmission process, the frame generation unit 162 outputs an operation instructing to insert the transmission time of Pdelay_Resp into Pdelay_Resp_Follow_Up in association with Pdelay_Resp. Then, the operation analysis unit 141 controls the transmission time insertion unit 156 according to the operation, and inserts the transmission time of Pdelay_Resp at a predetermined position of Pdelay_Resp_Follow_Up.

The protocol processing unit 160 performs processing on a received frame and generation of a transmission frame.
The analysis unit 161 analyzes the received frame. In particular, the analysis unit 161 determines whether the received frame is Pdelay_Req.
The frame generation unit 162 corresponds to an example of a transmission signal generation unit, and generates a transmission frame. In particular, the frame generation unit 162 generates Pdelay_Resp that stores reception time information indicating the reception time at which the frame reception unit 111 receives Pdelay_Req.

Next, the operation of the delay measurement signal transmission device 11 will be described with reference to FIGS.
FIG. 8 is an explanatory diagram illustrating an example of a processing procedure in which the delay measurement signal transmission device 11 performs a one-time transmission process. As shown in the figure, when the frame reception unit 111 of the transmission / reception unit 110 receives Pdelay_Req (sequence S101), the reception time adding unit 132 of the time processing unit 120 acquires the reception time (time T2) of Pdelay_Req and sets it to Pdelay_Req. It is added (sequence S102). The reception time adding unit 132 outputs Pdelay_Req to which the reception time is added to the protocol processing unit 160.

  When the analysis unit 161 of the protocol processing unit 160 analyzes the received frame and determines that it is Pdelay_Req (sequence S111), the frame generation unit 162 generates Pdelay_Resp storing the reception time (sequence S112). The frame generation unit 162 adds an operation instructing the difference calculation to Pdelay_Resp and outputs it to the time processing unit 120. The difference calculation here is the calculation of the difference time (time Td) obtained by subtracting the reception time (time T2) of Pdelay_Req from the transmission time (time T3) of Pdelay_Resp.

In the time processing unit 120, the difference time calculation unit 152 acquires the current time as the transmission time of Pdelay_Resp according to the operation for instructing the difference calculation (sequence S121), and calculates the difference time (sequence S122). Then, the difference time reflection unit 153 stores the difference time obtained in the sequence S122 at a predetermined position of Pdelay_Resp (sequence S123). The difference time reflection unit 153 outputs Pdelay_Resp storing the difference time to the transmission / reception unit 110.
In the transmission / reception unit 110, the frame transmission unit 112 transmits Pdelay_Resp storing the difference time to the delay measurement signal requesting apparatus 12 via the communication network 900 (sequence S124).

  FIG. 9 is an explanatory diagram illustrating an example of a processing procedure in which the delay measurement signal transmission device 11 performs a transmission process twice. Sequences S201 to S211 in the figure are the same as the sequences S101 to S111 in FIG. In the sequence S212 in FIG. 9, the frame generation unit 162 generates a Pdelay_Resp that stores the reception time, as in the sequence S112 in FIG. However, unlike the case of FIG. 8, the frame generation unit 162 adds an operation instructing time storage to Pdelay_Resp and outputs it to the time processing unit 120. The time storage here is to store the transmission time of Pdelay_Resp.

  The frame generation unit 162 outputs an operation according to whether or not the delay measurement signal requesting device 12 that has transmitted Pdelay_Req is compatible with a one-time transmission process. When it is determined that the delay measurement signal requesting device 12 that has transmitted Pdelay_Req is compatible with the one-time transmission processing, the frame generation unit 162 outputs an operation for instructing difference calculation as described with reference to FIG. To do. On the other hand, when it is determined that the delay measurement signal requesting device 12 that has transmitted Pdelay_Req does not support the one-time transmission process, the frame generation unit 162 performs an operation for instructing time storage as described above, and a time to be described later. Outputs an operation that instructs notification.

Whether or not the delay measurement signal requesting device 12 that has transmitted Pdelay_Req is compatible with the one-time transmission processing is determined by, for example, analyzing Pdelay_Req by the analysis unit 161. In this case, the delay measurement signal requesting device 12 includes information indicating whether or not the one-time transmission process is supported in the Pdelay_Req, and the analysis unit 161 transmits the Pdelay_Req. Is determined based on the information.
Alternatively, the delay measurement in which Pdelay_Req is transmitted by a method other than the analysis of Pdelay_Req, such as storing in advance for each delay measurement signal requesting device 12 whether or not the frame generation unit 162 supports the one-time transmission process. It may be determined whether or not the signal requesting device 12 is compatible with the one-time transmission process.

In time processing unit 120, transmission time storage unit 155 acquires and stores the current time as the transmission time of Pdelay_Resp in accordance with the operation for instructing time storage (sequence S221).
In addition, the time processing unit 120 outputs (transfers) the Pdelay_Resp from the protocol processing unit 160 to the transmission / reception unit 110. In the transmission / reception unit 110, the frame transmission unit 112 transmits the Pdelay_Resp to the delay measurement signal requesting apparatus 12 via the communication network 900 (sequence S222).

  The frame generation unit 162 of the protocol processing unit 160 generates Pdelay_Resp_Follow_Up (sequence S231), adds an operation for instructing time notification to the Pdelay_Resp_Follow_Up, and outputs the result to the time processing unit 120. The time notification here is to notify the delay measurement signal requesting device 12 of the transmission time of Pdelay_Resp.

In time processing unit 120, transmission time insertion unit 156 acquires the transmission time of Pdelay_Resp from transmission time storage unit 155 and stores it in a predetermined position of Pdelay_Resp_Follow_Up in accordance with an operation for instructing time notification (sequence S232).
Then, the transmission time insertion unit 156 outputs Pdelay_Resp_Follow_Up storing the transmission time of Pdelay_Resp to the transmission / reception unit 110. In the transmission / reception unit 110, the frame transmission unit 112 transmits the Pdelay_Resp_Follow_Up to the delay measurement signal requesting apparatus 12 via the communication network 900 (sequence S233).

FIG. 10 is a flowchart illustrating a procedure of processing in which the delay measurement signal transmission device 11 responds to Pdelay_Req. When the frame receiving unit 111 receives Pdelay_Req, the delay measuring signal transmission device 11 performs the processing illustrated in FIG.
When the frame analysis unit 131 detects a received frame in the processing of the figure, the reception time adding unit 132 acquires the current time from the clock unit 121 as the reception time (time T2) of Pdelay_Req and adds it to Pdelay_Req ( Step S301).

Next, when the analysis unit 161 analyzes the received frame and determines that it is Pdelay_Req, the frame generation unit 162 generates a frame as Pdelay_Resp (step S302). Then, the frame generation unit 162 stores the reception time added to the Pdelay_Req by the reception time adding unit 132 in Step S301 in the Pdelay_Resp (Step S303).
In addition, the frame generation unit 162 adds an operation to Pdelay_Resp (step S304). Here, the frame generation unit 162 adds either the operation for instructing the difference calculation described with reference to FIG. 8 or the operation for instructing the time storage described with reference to FIG.

Next, the operation analysis unit 141 analyzes the operation and determines whether or not the operation is an operation for instructing the difference calculation (step S305).
When it is determined that the operation is an operation for instructing the difference calculation (step S305: YES), the difference time calculation unit 152 acquires the current time from the clock unit 121 as the transmission time (time T3) of Pdelay_Resp (step S311). Further, the difference time calculation unit 152 reads the reception time (time T2) of Pdelay_Resp from Pdelay_Resp (step S312). And the difference time calculation part 152 calculates difference time (time Td = T3-T2) (step S313).

The difference time reflection unit 153 stores the difference time calculated by the difference time calculation unit 152 in a predetermined position of Pdelay_Resp (step S314). The frame transmitting unit 112 transmits the Pdelay_Resp in which the differential time reflecting unit 153 stores the differential time to the delay measurement signal requesting device 12 via the communication network 900 (step S315). Steps S311 to S315 correspond to an example of a procedure of a one-time transmission process.
After step S315, the process of FIG.

On the other hand, when it is determined in step S305 that the operation is not an operation for instructing difference calculation (step S305: NO), the operation analysis unit 141 determines whether the operation is an operation for instructing time storage (step S321).
When it is determined that the operation is an operation for instructing time storage (step S321: YES), the transmission time storage unit 155 acquires the current time from the clock unit 121 as the transmission time of Pdelay_Resp and stores it (step S331).

Further, the time processing unit 120 outputs (transfers) the Pdelay_Resp from the frame generation unit 162 to the frame transmission unit 112, and the frame transmission unit 112 transmits the Pdelay_Resp to the delay measurement signal requesting device 12 via the communication network 900. Transmit (step S332).
Further, the frame generation unit 162 generates Pdelay_Resp_Follow_Up (step S333). Then, the frame generation unit 162 adds an operation for instructing time notification to Pdelay_Resp_Follow_Up (step S334).
After step S334, the process proceeds to step S305.

On the other hand, if it is determined in step S321 that the operation is not an instruction to store time (step S321: NO), the transmission time insertion unit 156 acquires the transmission time of Pdelay_Resp from the transmission time storage unit 155, and the predetermined time of Pdelay_Resp_Follow_Up Store in the position (step S341).
Then, the frame transmission unit 112 transmits the Pdelay_Resp_Follow_Up in which the transmission time insertion unit 156 stores the transmission time to the delay measurement signal requesting device 12 via the communication network 900 (step S342). Steps S321 to S342 correspond to an example of the procedure of the twice transmission process.
After step S342, the process of FIG. 10 ends.

As described above, the difference time calculation unit 152 calculates the difference time obtained by subtracting the reception time of Pdelay_Req from the current time as the transmission time of Pdelay_Resp. Then, the difference time reflection unit 153 stores the difference time calculated by the difference time calculation unit 152 in the Pdelay_Resp generated by the frame generation unit 162. The frame transmission unit 112 transmits the Pdelay_Resp in which the differential time reflection unit 153 stores the differential time.
Thus, the delay measurement signal requesting device 12 that has received Pdelay_Resp can calculate the transmission delay time without having to receive another signal such as Pdelay_Resp_Follow_Up. As described above, according to the delay measurement signal transmitting apparatus 11, it is only necessary to transmit Pdelay_Resp to Pdelay_Req, and there is no need to further transmit other signals such as Pdelay_Resp_Follow_Up.
In this respect, according to the signal transmitter for delay measurement 11, it is possible to reduce the consumption of communication resources when measuring the transmission delay time. In addition, the load on the delay measurement signal transmission device 11 and the load on the delay measurement signal request device 12 can be reduced in that other signals such as Pdelay_Resp_Follow_Up need not be further transmitted and received.

In addition, the differential time calculation unit 152 calculates the differential time by acquiring the current time as the transmission time of Pdelay_Resp after the transmission destination of Pdelay_Resp is determined, for example, after the ARP processing is completed.
As a result, the time fluctuation from the time when the differential time calculation unit 152 acquires the current time as the transmission time of Pdelay_Resp to the time when the frame transmission unit 112 transmits Pdelay_Resp includes the time fluctuation of ARP processing and the like. Absent. In this regard, the fluctuation of the difference time calculated by the difference time calculation unit 152 with respect to the actual time from when the frame reception unit 111 receives Pdelay_Req to when the frame transmission unit 112 transmits Pdelay_Resp can be reduced.

Here, in a general method for executing the Peer Delay mechanism corresponding to IEEE 1588v2, a process for marking a frame transmission / reception time such as a frame transmission time is performed in the MAC layer or the PHY layer, but is a complicated process. Is performed in a layer higher than the MAC layer. If the difference time obtained by subtracting the reception time of Pdelay_Req from the transmission time of Pdelay_Resp is calculated in a layer higher than the MAC layer and embedded in Pdelay_Resp, the ARP processing is performed after the difference time is embedded in Pdelay_Resp. Since the time required for the ARP process is large, the difference time embedded in Pdelay_Resp increases with respect to the actual time from reception of Pdelay_Req to transmission of Pdelay_Resp.
On the other hand, since the delay measurement signal transmitter 11 stores the difference time in Pdelay_Resp after performing the ARP processing as described above, the Pdelay_Resp from the reception of the Pdelay_Req of the difference time embedded in the Pdelay_Resp. Fluctuation with respect to the actual time until transmission is small.

In addition, the operation analysis unit 141 performs a one-time transmission process in which the frame transmission unit 112 transmits the Pdelay_Resp in which the difference time reflection unit 153 stores the difference time, a Pdelay_Resp in which the reception time of the Pdelay_Req is stored, and the Pdelay_Resp transmission time Is switched to the twice transmission process in which the frame transmission unit 112 transmits Pdelay_Resp_Follow_Up in which is stored.
As a result, the delay measurement signal transmission device 11 performs the two-time transmission processing (transmission of Pdelay_Resp and Pdelay_Resp_Follow_Up) to the delay measurement signal request device 12 that does not support the one-time transmission processing (transmission of only Pdelay_Resp). Can provide information for transmission delay measurement.

  In the delay measurement signal transmitter 11, the twice transmission process is not essential. For example, the delay measurement signal transmission device 11 may not include the twice transmission processing unit 154, the transmission time storage unit 155, and the transmission time insertion unit 156. In this case, the delay measuring signal transmitter 11 always makes a transition to step S311 in step S305 of FIG.

As in the case of the two-time transmission process described above, when the time synchronization master device transmits a Sync (time synchronization signal), the frame of the Sync transmission time may be stored in the MAC layer. . This point will be described with reference to FIGS. 11 and 12.
FIG. 11 is a schematic block diagram illustrating a functional configuration of the master device according to a modification of the present embodiment. As shown in the figure, the master device 200 includes a frame transmission unit 212, a time processing unit 220, and a frame generation unit 262. The time processing unit 220 includes a clock unit 121, an operation analysis unit 241, and a transmission frame time processing unit 250. The transmission frame time processing unit 250 includes a transmission time storage unit 255 and a transmission time stamping unit 256.
11 corresponding to those in FIG. 6 are denoted by the same reference numerals (131, 900) and description thereof is omitted.

The master device 200 communicates with the slave device via the communication network 900. In particular, the master device 200 transmits Sync, which is a frame for time synchronization, and Sync_Follow_Up, which is a frame indicating the transmission time of Sync. The slave device performs time synchronization with the master device 200 with reference to these frames.
The master device 200 does not depend on the communication method of the communication network 900. For example, the communication network 900 may be Ethernet (registered trademark), but is not limited thereto. Further, the format of the signal transmitted by the master device 200 is not limited to the frame format.

The frame generation unit 262 generates a transmission frame (a frame transmitted by the frame transmission unit 112). In particular, the frame generation unit 262 generates Sync that is a frame for time synchronization. Also, the frame generation unit 262 generates Sync_Follow_Up, which is a frame indicating the transmission time of Sync. However, the transmission time stamping unit 256 stores the Sync transmission time in Sync_Follow_Up.
The frame generation unit 262 outputs an operation (operation command) in association with the frame. With this operation, the time processing unit 220 performs processing corresponding to each of Sync and Sync_Follo_Up.

The time processing unit 220 performs processing related to the transmission time of Sync. Specifically, the time processing unit 220 detects and stores the transmission time of Sync and stores it in Sync_Follow_Up.
The operation analysis unit 241 analyzes the operation that the frame generation unit 262 outputs in association with the frame.

The transmission frame time processing unit 250 performs processing for storing the transmission time of Sync in Sync_Follow_Up.
The transmission time storage unit 255 stores the transmission time of Sync. Specifically, the transmission time storage unit acquires and stores the current time from the clock unit 121 as the transmission time of the Sync according to the operation analysis result by the operation analysis unit during the transmission of the Sync.

The transmission time stamping unit 256 stores the Sync transmission time in Sync_Follow_Up. Specifically, the transmission time storage unit 255 acquires the Sync transmission time stored in the transmission time storage unit 255 and stores it in Sync_Follow_Up according to the operation analysis result by the operation analysis unit when the Sync_Follow_Up is transmitted.
The frame transmission unit 212 transmits a signal to another device via the communication network 900 in the form of a frame. In particular, the frame transmission unit 212 transmits Sync and Sync_Follow_Up to the slave device.

Similarly to the case of the delay measurement signal transmission device 11, the master device 200 also has each layer of a PHY layer (physical layer), a MAC layer, an IP layer, a UDP layer, and a PTP layer in order from a lower layer as a communication protocol. The frame generation unit 262 is provided in an upper layer from the IP layer among these layers. However, in the case of L2-type PTP, the IP layer and the UDP layer do not exist, and the PTP layer is directly above the MAC layer. That is, the protocol processing unit 160 may be provided in a layer higher than the MAC layer among these layers.
On the other hand, the time processing unit 220 is provided in the MAC layer like the time processing unit 120. Then, the transmission time storage unit 255 acquires the current time from the clock unit 121 and stores it as the transmission time of the Sync after completing the ARP process when transmitting the Sync.

  FIG. 12 is an explanatory diagram illustrating an example of a processing procedure in which the master device 200 transmits Sync and Sync_Follow_Up. As shown in the figure, the frame generation unit 262 generates Sync (sequence S401), adds an operation instructing time storage to the Sync, and outputs it to the time processing unit 220. The time storage here is to store the transmission time of Sync.

In time processing unit 220, transmission time storage unit 255 acquires and stores the current time as the transmission time of Sync (time Ts) in accordance with the operation for instructing time storage (sequence S411).
In addition, the time processing unit 220 outputs (transfers) the Sync from the frame generation unit 262 to the frame transmission unit 212. The frame transmission unit 212 transmits the Sync to the slave device via the communication network 900 (sequence S412).

  Further, the frame generation unit 262 generates Sync_Follow_Up (sequence S401), adds an operation instructing storage reflection to the Sync_Follow_Up, and outputs the operation to the time processing unit 220. The storage reflection here is to store the Sync transmission time stored in the transmission time storage unit 255 in Sync_Follow_Up.

  In the time processing unit 220, the transmission time stamping unit 256 acquires the Sync transmission time (time Ts) from the transmission time storage unit 255 in accordance with the operation for instructing the storage reflection, and stores it in a predetermined position of Sync_Follow_Up ( (Sequence S422). The frame transmission unit 212 transmits the Sync_Follow_Up to the slave device via the communication network 900 (sequence S412).

As described above, the time processing unit 220 performs processing for storing the transmission time of the Sync in the Sync_Follow_Up in the MAC layer.
As a result, the load on the upper layer than the MAC layer can be reduced.

A program for realizing all or part of the functions of the time processing units 120 and 220 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed. The processing of each unit may be performed as necessary. Here, the “computer system” includes an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Delay measurement system 11 Delay measuring signal transmitter 110 Transmission / reception part 111 Frame reception part 112 Frame transmission part 120 Time processing part 121 Clock part 131 Frame analysis part 132 Reception time addition part 141 Operation analysis part 150 Transmission frame time processing part 151 1 Time transmission processing unit 152 Difference time calculation unit 153 Difference time reflection unit 154 Twice transmission processing unit 155 Transmission time storage unit 156 Transmission time insertion unit 160 Protocol processing unit 161 Analysis unit 162 Frame generation unit

Claims (6)

A receiver for receiving the signal;
A signal generator for transmission that generates a signal for transmission storing reception time information indicating a reception time when the signal is received by the receiver;
A difference time calculation unit for calculating a difference time obtained by subtracting the reception time indicated by the reception time information from a current time;
A difference time reflection unit that stores information indicating the difference time calculated by the difference time calculation unit in the transmission signal generated by the transmission signal generation unit;
A transmission unit that transmits the transmission signal in which the difference time reflection unit stores information indicating the difference time; and
A signal transmission device for delay measurement comprising: The difference time calculation unit obtains the current time after calculating the transmission destination of the transmission signal, and calculates the difference time.
The signal transmission device for delay measurement according to claim 1. The transmission unit transmits the transmission signal in which the difference time reflecting unit stores information indicating the difference time, and the transmission unit stores information indicating the reception time. The delay measurement according to claim 1, further comprising a switching unit that switches between a transmission signal and a two-time transmission process for transmitting a second transmission signal in which information indicating a transmission time of the first transmission signal is stored. Signal transmitter. A delay measurement signal requesting device that transmits a request signal for requesting transmission of a delay measurement signal, and obtains a communication delay time based on the obtained delay measurement signal;
A signal transmission device for delay measurement that transmits the signal for delay measurement in response to the request signal;
With
The signal transmission device for delay measurement is
A receiving unit for receiving the request signal;
A transmission signal generator for generating a transmission signal storing reception time information indicating a reception time at which the reception unit has received the request signal;
A difference time calculation unit for calculating a difference time obtained by subtracting the reception time indicated by the reception time information from a current time;
A differential time reflection unit that generates the delay measurement signal by storing information indicating the differential time calculated by the differential time calculation unit in the transmission signal generated by the transmission signal generation unit;
A transmitter for transmitting the delay measurement signal;
A delay measurement system comprising: A delay measuring signal transmitting apparatus for receiving a signal; and
A signal generation step for transmission for generating a transmission signal storing reception time information indicating a reception time at which the signal transmission device for delay measurement has received the signal in the reception step;
The delay measurement signal transmitting device calculates a difference time by subtracting the reception time indicated by the reception time information from a current time;
The delay measurement signal transmitting apparatus stores, in the transmission signal generated in the transmission signal generation step, a difference reflection step of storing information indicating the difference time calculated in the difference time calculation step;
The delay measuring signal transmitting apparatus transmits the transmitting signal storing the information indicating the difference time in the difference reflecting step; and
A signal transmission method for delay measurement, comprising: In the computer that controls the signal transmission device for delay measurement,
A receiving step for receiving a signal;
A transmission signal generation step for generating a transmission signal storing reception time information indicating a reception time at which the signal is received in the reception step;
A difference time calculation step of calculating a difference time obtained by subtracting the reception time indicated by the reception time information from a current time;
A difference reflection step of storing information indicating the difference time calculated in the difference time calculation step in the transmission signal generated in the transmission signal generation step;
A transmission step of transmitting the transmission signal storing information indicating the difference time in the difference reflection step;
A program for running

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