TW202234920A - Network translator and device translator - Google Patents

Abstract

This network translator (210) calculates a clock deviation between a TSN master (101) and a 5G time source (111), sets the calculated clock deviation to generate a message, and transmits the generated message to a device translator (220). The device translator receives a message from the network translator, calculates a clock deviation between the TSN master and the device translator by using the clock deviation between the TSN master and the 5G time source, sets the calculated clock deviation to generate a message, and transmits the generated message to the downstream side of a time synchronization network system (100).

Description

Network Converters and Device Converters

The present disclosure relates to a 5G (fifth generation mobile communication technology)-TSN (Time-Sensitive Networking, Time-Sensitive Networking) translator that takes into account the clock deviation.

In the time synchronization method of wired TSN spanning multiple segments, the link delay of each section and the clock offset of each section are calculated by exchanging delay measurement messages between adjacent devices. When the slave station obtains the time notified from the master device, it uses the cumulative value of the link delay of each upstream section and the cumulative value of the clock deviation of each upstream section to correct the communication with the master. The time difference of the device. Thereby, highly accurate time synchronization is realized. TSN is the abbreviation of Time-Sensitive Networking (Time-Sensitive Networking).

The 5G-TSN system is a TSN system that connects TSN devices via 5G in a wired manner. In the 5G-TSN system, the 5G interval is processed as a virtual machine. However, physically, in the 5G interval, a network translator (NW-TT (Network-side TSN Translator)) is configured on the side separated by the wireless interval, and A device translator (DS-TT (Device-side TSN Translator, device-side TSN translator)) is arranged on the other side across the wireless section. The converter is a machine with the function of wired TSN, also known as a TSN converter.

In the 5G network, the delay is different between uplink communication and downlink communication. Therefore, even if delay measurement messages are exchanged between NW-TT and DS-TT, the link delay in the 5G interval cannot be measured. Therefore, NW-TT and DS-TT use the situation that the machines in the 5G interval are synchronized at a time (5G time) independent of the TSN time, and measure the link delay of the 5G interval by time stamping of the 5G time. .

Non-Patent Document 1 discloses a conventional 5G-TSN network. It is assumed that in the conventional 5G-TSN network, the clock deviation of each of NW-TT and DS-TT relative to the Grand Master (GM) (the highest master station) of the 5G network is zero. Furthermore, the DS-TT puts the clock offset of the NW-TT relative to the GM of the TSN into the time forwarding message Sync/Follow_Up, and transmits the time forwarding message to the downstream TSN slave station. [Prior Art Literature] [Non-patent literature]

Non-Patent Document 1: 3GPP TS 23.501 V16.4.0 (2020-03) "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 16)"

[The problem to be solved by the invention]

Conventionally, there is no method for calculating the clock offset between DS-TT and NW-TT. Therefore, the clock deviation in the 5G interval is not considered. For this reason, synchronization timing errors are generated at the TSN slave stations located downstream of the DS-TT.

The purpose of the present disclosure is to consider clock skew in 5G-TSN, thereby suppressing synchronization timing errors at TSN slave stations located downstream of DS-TT. [means to solve the problem]

The network converter of the present disclosure is used in a mobile communication system provided between the upstream of the time-synchronized network system and the downstream of the aforementioned time-synchronized network system. The upstream of the time synchronization network system has a master station (master) belonging to the machine that becomes the time source of the time synchronization network system. The aforementioned mobile communication system includes a time server and a device converter that serve as a time source for the aforementioned mobile communication system. The device converter uses the clock deviation between the master station and the time server and the clock deviation between the time server and the device converter to calculate the clock deviation between the master station and the device converter, and set The calculated clock offset generates a message, and the generated message is sent to the downstream converter of the time synchronization network system. The aforementioned network converter is equipped with: a clock offset calculation unit for calculating the clock offset between the master station and the time server; and The intra-interval communication unit generates a message by setting the clock deviation between the master station and the time server, and transmits the generated message to the device converter. [Effect of invention]

According to the present disclosure, it is possible to consider the clock deviation in 5G-TSN, and suppress the synchronization timing error of the TSN slave station located downstream of the DS-TT.

In the embodiment and the drawings, the same reference numerals are attached to the same elements or corresponding elements. Descriptions of elements with the same symbols as those described are omitted or simplified as appropriate. The arrows in the figure mainly indicate the flow of data or the flow of processing.

Embodiment 1 The time synchronization network system 100 will be described with reference to FIGS. 1 to 13 .

The time synchronization network system 100 is a time synchronization network system in which a plurality of network devices are connected via a mobile communication system. The time synchronization network system is a network system for time synchronization of a plurality of network devices. A network device is a device with a communication function.

Specifically, the time synchronization network system 100 is a 5G-TSN system. 5G is the fifth generation mobile communication system. The fifth-generation mobile communication system is an example of a mobile communication system. TSN is a time-synchronized network system called time-sensitive network.

＊＊＊Explanation of composition＊＊＊ The configuration of the time synchronization network system 100 will be described with reference to FIG. 1 . The time synchronization network system 100 includes a TSN master station 101 , a first bridge 102 , a TSN slave station 121 , and an Mth bridge 122 . These are network appliances of TSN.

The TSN master station 101 is a network device that becomes a time source in TSN, and is called the highest master station (GM). The side where the TSN master station 101 is located is referred to as "upstream". The TSN slave station 121 is a network device that synchronizes with the time of the TSN master station 101 . The side where the TSN slave station 121 is located is referred to as "downstream". The TSN master station 101 is described as "GM". The TSN slave station 121 is described as "SLAVE".

The first bridge 102 is the first bridge counted from the TSN master station 101 in the communication path from the TSN master station 101 to the TSN slave station 121 . A bridge is a type of network machine. The M-th bridge 122 is the M-th bridge counted from the TSN master station 101 in the communication path from the TSN master station 101 to the TSN slave station 121 . The first bridge 102 is arranged on the upstream side with respect to the 5G network 110 , and the M-th bridge 122 is arranged on the downstream side with respect to the 5G network 110 . The first bridge 102 is described as "S1". The M-th bridge 122 is described as "SM".

The time synchronization network system 100 includes a 5G time source 111 , a network converter 210 , and a device converter 220 . These are network devices of the 5G network 110 .

The 5G time source 111 is a network machine that becomes the time source of the 5G network 110, and is called a time server (TS). The 5G time source 111 is recorded as "5G-TS". The time of the 5G network 110 is independent of the time of the TSN.

The network switch 210 is a switch that performs network connection between 5G and TSN, has a time synchronization function of TSN, and is arranged on the upstream side of the 5G network 110 . The device switch 220 is a switch for connecting the 5G-TSN network, has a time synchronization function of TSN, and is arranged on the downstream side of the 5G network 110 . The network switch 210 and the device switch 220 are also referred to as TSN switches (TT). The network converter 210 is described as "NW-TT". The device converter 220 is described as "DS-TT".

The hardware configuration of the converter 300 will be described with reference to FIG. 2 . The switch 300 is a general term for the network switch 210 and the device switch 220 .

The converter 300 includes a mother board 310 and an expansion card 320 . The main board 310 is connected to a computer 301 for control. The motherboard 310 includes a processor 311 , a serial communication device 312 , and a converter circuit 313 . These are connected to each other by busses. This bus, also called a data bus, makes connections for register access (set, read) from the processor 311 .

The processor 311 is an electronic circuit that performs arithmetic processing, and includes a logic circuit, a primary cache, and the like. The serial communication device 312 is a device for serial communication. Specifically, serial communication device 312 is a UART. UART is the abbreviation of Universal Asynchronous Receiver/Transmitter (Universal Asynchronous Receiver Transmitter). The converter circuit 313 is an electronic circuit having the function of a converter. Specifically, the converter circuit 313 is an FPGA circuit, and the function of the converter is constructed by programmable logic. FPGA is the abbreviation of Field-Programmable Gate Array (Field Programmable Gate Array).

The expansion card 320 is also called a mezzanine card or a daughter card, and is connected to the motherboard 310 . Specifically, the expansion card 320 is connected to a dedicated connector provided on the motherboard 310 . The expansion card 320 is provided with a port 321 and a port 322 . Port 321 is a port connected to TSN, and port 322 is a port connected to 5G. Specifically, the port 321 and the port 322 are ports called SFPs. SFP is short for Small Form Factor Pluggable.

The functional configuration of the network converter 210 will be described with reference to FIG. 3 . The network converter 210 includes elements such as an out-of-zone communication unit 211 , a delay measurement unit 212 , a time synchronization control unit 213 , a clock offset calculation unit 214 , and an intra-area communication unit 215 . These elements are realized by the converter circuit 313 .

The out-of-zone communication unit 211 transmits and receives with the TSN. In addition, the out-of-zone communication unit 211 analyzes the received frame, extracts a header and a message from the received PTP frame, and terminates it. In addition, the out-of-zone communication unit 211 performs error check and length measurement, and discards the error check. In addition, the out-of-zone communication unit 211 notifies the delay measurement unit 212 of the transmission and reception time of the PTP frame. Therefore, the out-of-zone communication unit 211 holds the 5G time (TSi) when the network switch 210 receives the Sync message. PTP stands for Precision Time Protocol (Precision Time Protocol).

The delay measurement unit 212 uses a peer-to-peer (P2P) bus delay algorithm (P2P) called Pdelay_Req, Pdelay_Resp, and Pdelay_Resp_Follow_Up to measure the time-to-time synchronization between adjacent TSN devices. delay time and pulse deviation. The clock skew is calculated according to the time difference of the P2P delay measurement messages. The delay measurement unit 212 generates status information about transmission and reception control of PTP messages (Pdelay_Req, Pdelay_Resp, Pdelay_Resp_Follow_Up) and delay measurement functions. PTP messages are messages specified by IEEE 802.1 AS.

The delay measurement unit 212 measures the transmission delay between the network switch 210 and the adjacent TSN equipment to measure the link delay.

The time synchronization control unit 213 adds the accumulated clock deviation from the GM and the accumulated delay from the GM calculated by the self-device to the time information (the GM is the starting point) transmitted from the adjacent TSN device (upstream), and calculates the time between the GM and the GM. The time after the time is synchronized. Thereby, the synchronization time is configured to follow the GM.

The clock offset calculation unit 214 calculates the 5G time using the clock offset between the device and the GM calculated by the delay measurement unit 212 and the clock offset between the device and the 5G time source calculated by the intra-section communication unit 215 The clock offset of the source and the GM.

The intra-zone communication unit 215 provides the time synchronized with the 5G time source 111 . In addition, the intra-section communication unit 215 calculates the clock offset between the device and the source of the 5G time. In addition, the intra-section communication unit 215 adds the 5G time (TSi) when the network converter 210 received the Sync message and the accumulated clock offset between the GM and the 5G time source calculated by the clock offset calculation unit 214 to the Follow_Up message. TLV1 area, and send the Follow_Up message to 5G.

In addition, the function of each element will be described later.

The functional configuration of the device converter 220 will be described with reference to FIG. 4 . The device converter 220 includes elements such as an intra-section communication unit 221 , a delay measurement unit 222 , a clock deviation calculation unit 223 , and an out-of-section communication unit 224 . These elements are realized by the converter circuit 313 .

The intra-zone communication unit 221 transmits and receives with 5G. In addition, the intra-zone communication unit 221 extracts, from the TLV1 area of the received Follow_Up message, the 5G time (TSi) when the network converter 210 received the Sync message, and the source of the GM and 5G time calculated by the network converter 210 The information such as the clock offset is accumulated, and the extracted information is sent to the delay measurement unit 222 .

The delay measurement unit 222 receives the 5G time (TSe) when the Sync message is transmitted from the out-of-zone communication unit 224 . The delay measurement unit 222 calculates the delay measurement unit 222 using the TSi received from the intra-area communication unit 221 , the accumulated clock offset from the GM and 5G time received from the intra-area communication unit 221 , and the TSe received from the out-of-area communication unit 224 . Latency inside 5G. Furthermore, the delay measurement unit 222 transmits the delay time within the 5G to the out-of-zone communication unit 224 .

The clock offset calculation unit 223 uses the clock offset between the device and the 5G time source received from the out-of-area communication unit 224 and the accumulated clock offset from the GM and the 5G time source received from the intra-area communication unit 221 to calculate the source. The clock offset of the device from the GM. In addition, the clock offset calculation unit 223 transmits the clock offset between the own device and the GM to the out-of-area communication unit 224 .

The out-of-zone communication unit 224 transmits and receives with downstream TSN devices. In addition, the out-of-zone communication unit 224 receives and analyzes the PTP frame, extracts the header and the message from the received PTP frame, and terminates it. In addition, the out-of-zone communication unit 224 performs error checking, length measurement, and discards error frames. In addition, the out-of-zone communication unit 224 notifies the delay measurement unit 222 of the 5G time (TSe) at the time of transmission of the Sync message. The out-of-zone communication unit 224 adds the 5G internal delay time calculated by the delay measurement unit 222 to the correction field (correction field) of the Follow_Up message. In addition, the out-of-zone communication unit 224 rewrites the TLV of the Follow_Up message to the clock offset between the own device and the GM calculated by the clock offset calculation unit 223 . Furthermore, the out-of-zone communication unit 224 transmits the Follow_Up message to the downstream TSN device. In addition, the out-of-zone communication unit 224 calculates the clock offset between the device and the 5G time source, and sends it to the clock offset calculation unit 223 .

In addition, the function of each element will be described later.

＊＊＊Description of action＊＊＊ The procedure of the operation of the time synchronization network system 100 corresponds to the time synchronization method.

The clock offset calculation will be described with reference to FIG. 5 . The clock offset calculation is a process of calculating the clock offset CD _a between the network switch 210 and the adjacent TSN device, and is executed by the network switch 210 . TSN devices are network devices of TSN. The adjacent TSN device is specifically the first bridge 102 .

In step S111, the out-of-zone communication unit 211 receives the first delay measurement response message Pdelay_Resp from the adjacent TSN device. The delay measurement response message Pdelay_Resp is a response to the delay measurement request message Pdelay_Req.

In step S112, the out-of-area communication unit 211 acquires the first response reception time t _n . The first response receiving time t _n is the receiving time of the first delay measurement response message Pdelay_Resp. For example, the time of the converter 300 is obtained from a local operating system (OS).

In step S113, the out-of-zone communication unit 211 extracts the first response transmission time t' _n from the payload of the first delay measurement response message Pdelay_Resp_Follow_Up. The first response transmission time t' _n is the transmission time (ResponseOriginTimestamp) of the delay measurement response message Pdelay_Resp, which is measured and set by an adjacent TSN device.

In step S114, the out-of-section communication unit 211 waits for the Nth delay measurement response message Pdelay_Resp, and receives the Nth delay measurement response message Pdelay_Resp. "N" is an integer of 2 or more.

In step S115 , the out-of-area communication unit 211 acquires the Nth response reception time t _nn (PdelayRespEventIngressTimestamp). The Nth response reception time _tnn is the reception time of the Nth delay measurement response message Pdelay_Resp.

In step S116, the out-of-zone communication unit 211 extracts the Nth response transmission time t' _nn from the payload of the Nth delay measurement response message Pdelay_Resp_Follow_Up. The Nth response transmission time _t'nn is the transmission time (ResponseOriginTimestamp) of the delay measurement response message Pdelay_Resp, which is measured and set by the adjacent TSN device.

In step S117, the delay measurement unit 212 calculates the clock offset using the first response reception time _tn , the first response transmission time _t'n , the Nth response reception time _tnn , and the Nth response transmission time _t'nn CD _a . The clock offset CD _a is the clock offset between the network converter 210 and the adjacent TSN device.

The clock deviation CD _a is calculated by calculating the following formula (a). CD _a = (t _nn -t _n )/(t' _nn -t' _n ) (a)

The relationship between the clock deviation R _{NW_GM} and each time will now be described with reference to FIG. 6 . The clock deviation R _{NW_GM} corresponds to the clock deviation CD _a . The NW-TT transmits a delay measurement request message Pdelay_Req. The transmission time is time t ₁ . The GM receives the delay measurement request message Pdelay_Req. The reception time is time t ₂ . The GM transmits the first delay measurement response message Pdelay_Resp. The transmission time is time t' _n . The NW-TT receives the first delay measurement response message Pdelay_Resp. The reception time is time t _n . The GM transmits the Nth delay measurement response message Pdelay_Resp. The transmission time is time t' _nn . The NW-TT receives the Nth delay measurement response message Pdelay_Resp. The reception time is time t _nn . The clock offset R _{NW_GM} is calculated by calculating the above-mentioned formula (a).

The link delay calculation will now be described with reference to FIG. 7 . The link delay calculation is a process of calculating the link delay LD _b between the network switch 210 and the adjacent TSN device, and is executed by the network switch 210 . The link delay LD _b is the time equivalent to the transmission delay.

In step S121, the out-of-zone communication unit 211 transmits the delay measurement request message Pdelay_Req to the adjacent TSN device.

In step S122, the out-of-area communication unit 211 acquires the requested transmission time t ₁ . The required transmission time _t1 is the transmission time of the delayed measurement request message Pdelay_Req.

In step S123, the out-of-zone communication unit 211 waits for the delay measurement response message Pdelay_Resp from the adjacent TSN device, and receives the delay measurement response message Pdelay_Resp.

In step S124, the out-of-area communication unit 211 acquires the response reception time t ₄ . The response reception time t4 is the reception time of the delay measurement response message _{Pdelay_Resp} .

In step S125, the out-of-zone communication unit 211 extracts the request reception time t ₂ from the payload of the delay measurement response message Pdelay_Resp. The request reception time t ₂ is the reception time (RequestReceiptTimestamp) of the delay measurement request message Pdelay_Req, which is measured and set by an adjacent TSN device.

In step S126, the out-of-section communication unit 211 waits for the additional message Pdelay_Resp_Follow_Up of the delay measurement response message Pdelay_Resp, and receives the additional message Pdelay_Resp_Follow_Up.

In step S127, the out-of-zone communication unit 211 extracts the response transmission time t ₃ from the payload of the additional message Pdelay_Resp_Follow_Up. The response transmission time t ₃ is the transmission time (ResponseOriginTimeStamp) of the delay measurement response message Pdelay_Resp, which is measured and set by the adjacent TSN device.

In step S128, the delay measurement unit 212 calculates the link delay _LDb using the clock deviation _CDa , the requested transmission time _t1 , the response reception time _t4 , the requested reception time _t2 , and the response transmission time _t3 . The link delay LD _b is the link delay between the network switch 210 and the adjacent TSN machine.

The link delay LD _b is calculated by calculating the following formula (b). LD _b =(CD _a ×(t ₄ -t ₁ )-(t ₂ -t ₃ ))/2(b)

Time alignment will be described using FIG. 8 . The time alignment is a process of aligning the time of the network switch 210 with the time of the TSN master station 101 , and is performed by the network switch 210 .

In step S131, the out-of-zone communication unit 211 receives the synchronization message Sync from the adjacent TSN device.

In step S132, the out-of-zone communication unit 211 acquires the synchronous reception time TSi. The synchronization reception time TSi is the 5G time when the synchronization message Sync is received.

In step S133, the out-of-zone communication unit 211 waits for the additional message Follow_Up of the synchronization message Sync, and receives the additional message Follow_Up. Furthermore, the out-of-zone communication unit 211 transmits the synchronization message Sync to 5G.

In step S134, the out-of-section communication unit 211 extracts the accumulated clock deviation ACD' from the additional message Follow_Up. The cumulative clock deviation ACD' is the cumulative clock deviation of the TSN device adjacent to the network converter 210 and the TSN master station 101.

In step S135, the delay measurement unit 212 calculates the cumulative clock deviation ACD _C using the clock deviation CD _a and the cumulative clock deviation ACD'. Accumulated Clock Offset The accumulated clock offset of the ACD _C series network converter 210 and the TSN master station 101 .

The cumulative clock deviation ACD _C is calculated by calculating the following formula (c). ACD _C = ACD'×CD _a (C)

In step S136, the out-of-section communication unit 211 extracts the accumulated delay value AD' from the Correction field of the additional message Follow_Up. The accumulated delay value AD' is the accumulated delay value of the TSN device adjacent to the network switch 210 and the TSN master station 101.

In step S137, the delay measurement unit 212 calculates the accumulated delay AD _d using the accumulated delay value AD', the chain delay LD _b , and the accumulated clock deviation _ACDC . The accumulated delay AD _d is the accumulated delay between the network converter 210 and the TSN master 101 .

The accumulated delay AD _d is calculated by calculating the following formula (d). ADd=AD'+(LDb*ACD _C ) (d)

In step S138, the out-of-section communication unit 211 extracts the time TG from the additional message Follow_Up. The time TG is the time of the TSN master station 101 .

Furthermore, the time synchronization control unit 213 calculates the synchronization time ST _e using the time TG and the accumulated delay AD _d .

The synchronization time ST _e is calculated by calculating the following formula (e). ST _e =TG+AD _d (e)

In step S139, the time synchronization control unit 213 updates the time of the network switch 210 to the synchronization time ST _e to perform time alignment.

Additional message delivery (5G) will be described with reference to FIG. 9 . The additional message transmission (5G) is a process of transmitting the additional message Follow_Up from the network switch 210 in the 5G network 110 , and is executed by the network switch 210 .

In step S141, the intra-section communication unit 215 calculates the clock deviation CD _f . The clock deviation CD _f is the clock deviation between the 5G time source 111 and the network converter 210 .

In step S142, the clock deviation calculation unit 214 calculates the clock deviation CD _g using the accumulated clock deviation ACD _C and the clock deviation CD _f . The clock deviation CD _g is the clock deviation between the TSN master station 101 and the 5G time source 111 .

The clock deviation CD _g is calculated by calculating the following formula (g). CD _g =ACD _C ×CD _f (g)

In step S143, the intra-section communication unit 215 generates an additional message Follow_Up.

Specifically, the intra-section communication unit 215 operates as follows. The intra-section communication unit 215 sets the synchronization reception time TSi acquired in step S132 (see FIG. 8 ) in the TLV2 field of the additional message Follow_Up. The intra-section communication unit 215 sets the clock offset CD _g calculated in step S142 in the TLV1 field of the additional message Follow_Up. The intra-section communication unit 215 sets the cumulative delay AD _d calculated in step S137 (see FIG. 8 ) in the correction field of the additional message Follow_Up.

In step S144 , the intra-section communication unit 215 transmits the additional message Follow_Up to the device switch 220 .

Additional message delivery (TSN) will be described with reference to FIGS. 10 and 11 . The additional message transmission (TSN) is a process of transmitting the additional message Follow_Up from the device switch 220 to the TSN, and is performed by the device switch 220 .

In step S201 , the intra-section communication unit 221 receives the synchronization message Sync transmitted from the network switch 210 .

In step S202, the intra-section communication unit 221 waits for the additional message Follow_Up transmitted from the network switch 210, and receives the additional message Follow_Up. After step S202, the process proceeds to step S203 and step S211.

In step S203, the intra-section communication unit 221 extracts information from the additional message Follow_Up. After step S203, the process proceeds to step S221.

Specifically, the intra-section communication unit 221 operates as follows. The intra-section communication unit 221 extracts the synchronization reception time TSi from the TLV2 field of the additional message Follow_Up. The intra-section communication unit 221 extracts the clock offset CD _g from the TLV1 field of the additional message Follow_Up. The intra-section communication unit 221 extracts the accumulated delay AD _d from the correction field of the additional message Follow_Up.

In step S211, the out-of-zone communication unit 224 transmits the synchronization message Sync to the TSN. In other words, the out-of-zone communication unit 224 transmits the synchronization message Sync to the downstream TSN device. Specifically, the out-of-zone communication unit 224 transmits the synchronization message Sync to the Mth bridge 122 .

In step S212, the out-of-zone communication unit 224 acquires the synchronous transmission time TSe. The synchronization transmission time TSe is the 5G time when the synchronization message Sync is transmitted.

In step S213, the delay measurement unit 222 calculates the internal delay _IDh using the synchronous transmission time TSe and the synchronous reception time TSi extracted in step S203. The internal delay ID _h is the delay generated in the 5G network 110 . Specifically, the internal delay ID _h is the difference between the synchronous transmission time TSe and the synchronous reception time TSi.

The internal delay ID _h is calculated by calculating the following formula (h). ID _h =TSe-TSi(h)

In step S214, the delay measurement unit 222 calculates the cumulative delay AD _K using the internal delay ID _h , the cumulative delay AD _d extracted in step S203 , and the clock deviation CD _g extracted in step S203 . The accumulated delay AD _K is the accumulated delay between the device converter 220 and the TSN master 101 . After step S214, the process proceeds to step S223.

The accumulated delay AD _K is calculated by calculating the following formula (k). AD _K = AD _d + (ID _h × CD _g ) (k)

In step S221, the out-of-section communication unit 224 calculates the clock deviation CD _i . The clock offset CD _i is the clock offset between the 5G time source 111 and the device converter 220 .

In step S222, the out-of-section communication unit 224 calculates the clock deviation CD _j using the clock deviation CD _i and the clock deviation CD _g extracted in step S203. The clock deviation CD _j is the clock deviation between the TSN master station 101 and the device converter 220 .

The clock deviation CD _j is calculated by calculating the following formula (j). CD _j =CD _g ×CD _i formula (j)

In step S223, the out-of-area communication unit 224 generates an additional message Follow_Up.

Specifically, the out-of-zone communication unit 224 operates as follows. The out-of-section communication unit 224 sets the clock offset CD _j calculated in step S222 in the TLV1 field of the additional message Follow_Up. The out-of-section communication unit 224 sets the accumulated delay AD _K calculated in step S214 in the correction field of the additional message Follow_Up. The out-of-zone communication unit 224 deletes the TLV2 of Follow_Up.

In step S224, the out-of-zone communication unit 224 transmits the additional message Follow_Up to the TSN. In other words, the out-of-zone communication unit 224 transmits the additional message Follow_Up to the downstream TSN device. Specifically, the out-of-area communication unit 224 transmits the additional message Follow_Up to the Mth bridge 122 .

FIG. 12 shows the frame format of the additional message Follow_Up sent from the network switch 210 to the device switch 220 . The header contains the correction field. In the correction field, the accumulated delay AD _d is set. In the TLV1 field, the clock deviation CD _g is set. In the TLV2 field, the synchronization reception time TSi is set.

FIG. 13 shows the frame format of the follow-up message Follow_Up sent from the device switch 220 to the TSN. The header contains the correction field. In the correction field, the accumulated delay AD _K is set. In the TLV1 field, the clock offset CD _j is set.

***Features of Embodiment 1*** The features of Embodiment 1 will be described with reference to FIG. 14 . The slanted line with the arrow indicates the flow of the PTP message. The specific PTP message is the additional message Follow_Up. The time T _M is the transmission time of the PTP message in the GM. The time T _S1 is the time after S1 is synchronized with the GM. Time T _NW is the time after the NW-TT is synchronized with the GM. The time T _DS is the time after the DS-TT is synchronized with the GM. Time TSN is the time after _SN and GM are synchronized. _The delay D1 corresponds to the time from time _TM to time T _S1 . The delay _D5G corresponds to the time from time _TM to time _TDS . The delay _DN corresponds to the time from time _TM to time _TSN .

In each PTP message, in addition to the GM time, a clock offset R is also set. In the PTP message transmitted from GM to S1, the same clock offset R _GM (=1) as the conventional one is set. The clock offset R _GM is "1". In the PTP message transmitted from S1 to the NW-TT, the same clock offset R _{S1_GM} as the conventional one is set. The clock deviation R _{S1_GM} is the clock deviation between GM and S1. In the PTP message transmitted from the NW-TT to the DS-TT, a clock offset R _{5G_GM} which is different from the conventional one is set. In the conventional system, the clock offset R _{NW_GM} between GM and NW-TT is set. The clock deviation R _{NW_GM} corresponds to the accumulated clock deviation ACD _C (refer to step S135 ). The clock deviation R _{5G_GM} is the clock deviation between GM and 5G-TS, and corresponds to the clock deviation CD _g (refer to step S142 ). The clock deviation R _{5G_GM} is expressed as follows using the clock deviation R _{NW_GM} and the clock deviation R _{5G_GM} . The clock deviation R _{5G_GM} is the clock deviation between the 5G-TS and the NW-TT, and corresponds to the clock deviation CD _f (refer to step S141 ). R _{5G_GM} =R _{5G_NW} R _{NW_GM} In the PTP message sent from the DS-TT to the SM, a clock offset R _{DS_GM} which is different from the conventional one is set. The conventional system sets the clock deviation R _{NW_GM} . The clock deviation R _{DS_GM} is the clock deviation between GM and DS-TT, and corresponds to the clock deviation CD _j (refer to step S222 ). The clock deviation R _{DS_GM} is expressed as follows using the clock deviation R _{5G_GM} and the clock deviation R _{DS_GM} . The clock deviation R _{DS_GM} is the clock deviation between the 5G-TS and the DS-TT, and corresponds to the clock deviation CD _i (refer to step S221 ). R _{DS_GM} =R _{DS_5G} R _{5G_GM}

In other words, NW-TT and DS-TT operate as follows. The NW-TT system calculates the clock deviation R _{5G_NW} from the 5G-TS, and calculates the clock deviation R _{5G_GM} using the clock deviation R _{NW_5G} . Furthermore, the NW-TT transmits the clock offset R _{5G_GM} to the DS-TT in place of the clock offset R _{NW_GM} . The DS-TT system calculates the clock deviation R DS_5G from the 5G-TS, and calculates the clock deviation R _{DS_GM using} the clock deviation R _{DS_5G} and the clock deviation R _{5G_GM} . Furthermore, the DS-TT transmits the clock offset R _{DS_GM} to the SN in place of the clock offset R _{NW_GM} .

In the conventional method by 3GPP23.501, it is assumed that the clock skew of 5G-TS and NW-TT and the clock skew of NW-TT and DS-TT are zero. Therefore, the final time synchronization accuracy is not good. In the method of Embodiment 1, the clock deviation between 5G-TS and NW-TT and the clock deviation between NW-TT and DS-TT are considered.

*******Effects of Embodiment 1*** By means of Embodiment 1, the time error caused by the joining of the 5G network that does not exist in the TSN network to the TSN network can be eliminated, that is, due to the The time error caused by the clock deviation. Specifically, the network converter 210 and the device converter 220 are indirectly calculated by each of the network converter 210 and the device converter 220 using the clock offsets (CD _f , CD _i ) from the 5G time source 111 . clock skew between. Thereby, the synchronization time error of the TSN slave station 121 can be eliminated.

The first embodiment is advantageous in terms of cost because it is unnecessary to add control information by changing the existing time synchronization information.

＊＊＊Supplement to the embodiment ＊＊＊ The hardware configuration of the converter 300 is supplemented according to FIG. 15 . The converter 300 is provided with a processing circuit 309 . The processing circuit 309 is hardware that realizes the functional components of the network switch 210 or the device switch 220 . The processing circuit 309 may be dedicated hardware, or may be the processor 311 that executes the program stored in the memory.

When the processing circuit 309 is dedicated hardware, the processing circuit 309 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. ASIC is short for Application Specific Integrated Circuits. FPGA is the abbreviation of Field-Programmable Gate Array (Field Programmable Gate Array).

The converter 300 may include a plurality of processing circuits instead of the processing circuit 309 .

In the processing circuit 309, a part of the functions can be implemented by dedicated hardware, and the remaining functions can also be implemented by software or firmware.

As such, the functions of the converter 300 may be implemented by hardware, software, firmware, or a combination thereof.

Each embodiment is an illustration of a preferred form, and is not intended to limit the technical scope of the present disclosure. Each embodiment can be implemented locally or in combination with other forms. The procedures described using the flowcharts and the like may be appropriately changed.

A "section" that is an element of the network switch 210 or the device switch 220 may also be referred to as a "process," "step," "circuit," or "circuitry."

100: Time synchronization network system 101: TSN master station 102: First bridge 110: 5G network 111: 5G time source 121: TSN slave station 122: Mth bridge 210: Network converter 211: Out-of-area communication Section 212: Delay measurement section 213: Time synchronization control section 214: Clock deviation calculation section 215: Inter-section communication section 220: Device switch 221: In-section communication section 222: Delay measurement section 223: Clock deviation calculation section 224: External communication unit 300: Converter 301: Computer 309: Processing circuit 310: Motherboard 311: Processor 312: Serial communication device 313: Converter circuit 320: Expansion card 321: Port 322: Port ACD _C : Cumulative clock deviation AD': Accumulated delay value AD _d : Accumulated delay AD _K : Accumulated delay CD _a , CD _f , CD _g , CD _i , CD _j : Clock deviation D ₁ , D _5G , _DN : Delay ID _h : Internal delay LD _b : Link Delay Pdelay_Resp: Delay Measurement Response Message Pdelay_Req: Delay Measurement Request Message R,R _{5G_GM} ,R _{NW_GM} (=CDa),R _{NW_GM} ,R _{DS_GM} ,R _{S1_GM} ,R _GM ,R _{NW_5G} ,R _{DS_5G} : Clock Deviation ST _e : synchronization time Sync: synchronization messages t ₁ , t ₂ , t ₃ , t ₄ , T _DS , TG, T _M , T _NW , T _S1 , T _SN : time t _n : first response reception time t' _n : first response transmission time t _nn : Nth response reception time t' _nn : Nth response transmission time TSi : synchronous reception time TSe : synchronous transmission time

FIG. 1 is a diagram showing the configuration of a time synchronization network system 100 in the first embodiment. FIG. 2 is a hardware configuration diagram of the converter 300 in the first embodiment. FIG. 3 is a functional configuration diagram of the network converter 210 in the first embodiment. FIG. 4 is a functional configuration diagram of the device converter 220 in the first embodiment. FIG. 5 is a flowchart of clock offset calculation in Embodiment 1. FIG. FIG. 6 is a diagram showing the relationship between the clock deviation R _{NW_GM} (=CD _a ) and each time in the first embodiment. FIG. 7 is a flowchart of link delay calculation in Embodiment 1. FIG. FIG. 8 is a flowchart of time alignment in Embodiment 1. FIG. FIG. 9 is a flowchart of additional message transmission (5G) in Embodiment 1. FIG. FIG. 10 is a flowchart of additional message transmission (TSN) in Embodiment 1. FIG. FIG. 11 is a flowchart of additional message transmission (TSN) in Embodiment 1. FIG. FIG. 12 is a table showing the frame format of the additional message Follow_Up (NW-TT→DS-TT) in the first embodiment. FIG. 13 is a table showing the frame format of the additional message Follow_Up (NW-TT→TSN) in the first embodiment. FIG. 14 is a diagram showing the clock offset R set in each PTP (Precision Time Protocol, Precision Time Protocol) message in the first embodiment. FIG. 15 is a supplementary diagram of the hardware configuration of the converter 300 in the first embodiment.

100: Time synchronization network system

101:TSN Master (GM)

102: First bridge (S1)

110:5G network

111: 5G time source (5G-TS)

121:TSN slave station (SLAVE)

122: M-th Bridge (SM)

210: Network Converter (NW-TT)

220: Device Converter (DS-TT)

Claims (6)

A network converter is used in a mobile communication system provided between the upstream of a time synchronization network system and the downstream of the aforementioned time synchronization network system, The upstream of the aforementioned time synchronization network system has a master station belonging to the machine that becomes the time source of the aforementioned time synchronization network system, The aforementioned mobile communication system includes a time server and a device converter that serve as the time source of the aforementioned mobile communication system, The device converter uses the clock deviation between the master station and the time server and the clock deviation between the time server and the device converter to calculate the clock deviation between the master station and the device converter, and set The calculated clock offset generates a message, and transmits the generated message to the converter downstream of the time synchronization network system, The aforementioned network converter is equipped with: a clock offset calculation unit for calculating the clock offset between the master station and the time server; and The intra-interval communication unit generates a message by setting the clock deviation between the master station and the time server, and transmits the generated message to the device converter. The network converter of claim 1, wherein the network converter is provided with: a delay measurement unit for calculating the clock deviation between the master station and the network converter; and The intra-interval communication unit calculates the clock deviation between the network converter and the time server; The clock offset calculation unit calculates the clock offset between the master station and the time server using the clock offset between the master station and the network converter and the clock offset between the network switch and the time server. clock skew. A network switch as claimed in claim 1 or claim 2, wherein said message is transmitted from said network switch to said device switch and said information is transmitted from said device switch to said time synchronization network system downstream Each of the messages is an additional message of the Precision Time Protocol. A device converter is used in a mobile communication system provided between the upstream of the time synchronization network system and the downstream of the aforementioned time synchronization network system, The upstream of the aforementioned time synchronization network system has a master station belonging to the machine that becomes the time source of the aforementioned time synchronization network system, The above-mentioned mobile communication system has a time server and a network converter that become the time source of the above-mentioned mobile communication system, The network converter uses the clock offset between the master station and the network switch, and the clock offset between the network switch and the time server to calculate the clock offset between the master station and the time server , and set the calculated clock deviation to generate a message, and a converter that transmits the generated message, The aforementioned equipment converter is equipped with: The intra-interval communication unit receives the message from the network switch, and extracts the clock offset between the master station and the time server from the received message; a clock offset calculation unit for calculating the clock offset between the master station and the device converter using the clock offset between the master station and the time server; and The out-of-area communication unit generates a message by setting the clock deviation between the master station and the device converter, and transmits the generated message to the downstream of the time synchronization network system. The device converter of claim 4, wherein the out-of-region communication unit calculates a clock offset between the time server and the device switch, and uses the clock offset between the master station and the time server, and The clock deviation between the master station and the device converter is calculated by calculating the clock deviation between the time server and the device converter. A network switch as claimed in claim 4 or claim 5, wherein said message transmitted from said network switch to said equipment switch and said information transmitted from said equipment switch to said time synchronization network system downstream Each of the messages is an additional message of the Precision Time Protocol.

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