CN117978316A

CN117978316A - Clock synchronization method and system of wired-wireless hybrid TSN architecture

Info

Publication number: CN117978316A
Application number: CN202410197627.4A
Authority: CN
Inventors: 王峰; 曹万科; 王文伟; 张峰; 杜一鸣; 郭树勋; 陈俊协; 郑文香
Original assignee: Shenzhen Automotive Research Institute of Beijing University of Technology
Current assignee: Shenzhen Automotive Research Institute of Beijing University of Technology
Priority date: 2024-02-22
Filing date: 2024-02-22
Publication date: 2024-05-03

Abstract

The application relates to the technical field of clock synchronization, in particular to a clock synchronization method and system of a wired-wireless hybrid TSN architecture. According to the clock synchronization method, after the PTP slave device module acquires the reference clock information of the GMC highest-level clock, the clock information of the PTP slave device module is calibrated according to the reference time stamp information of the reference clock information so as to generate synchronous clock information, wherein the synchronous clock information comprises synchronous time stamp information; and sending the synchronous time stamp information in a wireless mode and a wired mode through the clock domain conversion module, so that the first external terminal which receives the synchronous time stamp information in a wireless mode and the second external terminal which receives the synchronous time stamp information in a wired mode can carry out clock synchronization according to the synchronous time stamp information. By adopting the scheme of the application, the external terminals of the wired network and the wireless network can keep high-precision clock synchronization, and further high-performance clock synchronization conversion between the wired network and the wireless network is possible.

Description

Clock synchronization method and system of wired-wireless hybrid TSN architecture

Technical Field

The invention relates to the technical field of clock synchronization, in particular to a clock synchronization method and system of a wired-wireless hybrid TSN architecture.

Background

Clock synchronization is considered as a core function of Time Sensitive Networks (TSNs) because TSNs are built under the condition that networks share a common time, and thus, the first step in achieving a hybrid TSN is to support accurate synchronization of wired and wireless networks, and seamless transitions in clock synchronization between them. In industrial applications, the TSN needs to achieve a strict clock synchronization and ensure that the maximum time offset between the master clock and the slave clock is controlled between 0.1 mus and 1 mus. However, achieving strict clock synchronization is a challenge for hybrid TSN networks, as different types of devices and communications may exist in the hybrid TSN network. These devices may have different hardware and clock accuracies, resulting in some variance in time synchronization.

At present, the research on the cross-network time synchronization at home and abroad is relatively few. Because of the high requirements of the industrial heterogeneous network on the characteristics of real-time performance, low delay and the like, the existing method is directly adopted, so that a plurality of requirements of the novel industrial heterogeneous network cannot be met.

Disclosure of Invention

The clock synchronization method and the clock synchronization system for the wired-wireless hybrid TSN architecture effectively solve the problem that in the prior art, clock synchronization between networks of the wired-wireless hybrid architecture is delayed, so that clock synchronization accuracy is low.

According to a first aspect, in one embodiment, a clock synchronization method of a wired-wireless hybrid TSN architecture is provided, including:

The PTP slave device module acquires reference clock information of the GMC highest-level clock, wherein the reference clock information comprises reference time stamp information; calibrating the clock information of the clock domain conversion module according to the reference time stamp information, generating synchronous clock information according to the calibrated clock information, and transmitting the synchronous time stamp information in the synchronous clock information to the clock domain conversion module;

The clock domain conversion module sends out the synchronous timestamp information in a wireless mode and a wired mode, so that a first external terminal which receives the synchronous timestamp information in a wireless mode and a second external terminal which receives the synchronous timestamp information in a wired mode can carry out clock synchronization according to the synchronous timestamp information.

In one implementation manner, the clock domain conversion module includes MTSN ethernet switches and a physical hardware clock unit, and the clock domain conversion module issues the synchronous timestamp information in a wireless manner and a wired manner, including:

Integrating a PTP time synchronization protocol of the synchronous clock information into a time sensitive network through the cable domain TSN-PTP driving module;

transmitting the synchronous clock information to the physical hardware clock module through the MTSN ethernet switch;

and synchronizing clock information of the physical hardware clock module according to the synchronous clock information so that the physical hardware clock module can send out the synchronous timestamp information in a wireless mode and a wired mode.

In an implementation manner, the wireless domain network module includes a wireless network driving unit and a wireless network modulation adjusting unit, and after the physical hardware clock module sends out the synchronous timestamp information in a wireless manner, the wireless domain network module includes:

Configuring an interface of the wireless network modulation adjustment unit through the wireless network driving unit so that the interface supports a PTP protocol;

and sharing the synchronous timestamp information to the first external terminal through the wireless network modulation adjusting unit.

In an implementation manner, after integrating the PTP time synchronization protocol of the synchronization clock information into a time sensitive network by the cable domain TSN-PTP driver module, the method further includes:

and transmitting the synchronous clock information to the second external terminal through the MTSN Ethernet switch.

In one implementation manner, after the clock domain conversion module sends out the synchronous timestamp information, the method further includes:

And carrying out frequency division processing on the synchronous timestamp information through a clock domain crossing circuit to obtain stable synchronous timestamp information, so that the clock domain conversion module sends out the stable synchronous timestamp information.

According to a second aspect, in one embodiment, there is provided a clock synchronization system of a wired-wireless hybrid TSN architecture, including:

the PTP slave device module is used for acquiring reference clock information of the GMC highest-level clock, wherein the reference clock information comprises reference timestamp information; calibrating the clock information of the clock domain conversion module according to the reference time stamp information, generating synchronous clock information according to the calibrated clock information, and transmitting the synchronous time stamp information in the synchronous clock information to the clock domain conversion module;

and the clock domain conversion module is used for sending the synchronous timestamp information in a wireless mode and a wired mode, so that a first external terminal which receives the synchronous timestamp information in a wireless mode and a second external terminal which receives the synchronous timestamp information in a wired mode can carry out clock synchronization according to the synchronous timestamp information.

In one implementation, the clock domain conversion module includes MTSN ethernet switches and a physical hardware clock unit; the clock domain conversion module sends out the synchronous timestamp information in a wireless mode and a wired mode, and the clock domain conversion module comprises the following components:

In an implementation manner, after integrating the PTP time synchronization protocol of the synchronous clock information into a time sensitive network by the cable domain TSN-PTP driver module, the clock domain conversion module further includes:

According to a third aspect, an embodiment provides a computer readable storage medium having stored thereon a program executable by a processor to implement a method as described above.

According to the clock synchronization method/system of the wired-wireless hybrid TSN architecture of the embodiment, after the PTP slave device module obtains the reference clock information of the GMC highest-level clock, calibrating the clock information of the PTP slave device module according to the reference time stamp information of the reference clock information, generating synchronous clock information according to the calibrated clock information, and sending the synchronous time stamp information in the synchronous clock information to the clock domain conversion module; and finally, sending out the synchronous timestamp information in a wireless mode and a wired mode through a clock domain conversion module, so that the first external terminal which receives the synchronous timestamp information in a wireless mode and the second external terminal which receives the synchronous timestamp information in a wired mode can carry out clock synchronization according to the synchronous timestamp information. By adopting the clock synchronization method/system, the external terminal of the wired network and the external terminal of the wireless network can keep high-precision clock synchronization, and further high-performance clock synchronization conversion between the wired network and the wireless network is possible.

Drawings

Fig. 1 is a flowchart of a clock synchronization method of a wired-wireless hybrid TSN architecture according to the present embodiment;

fig. 2 is a flowchart for synchronizing clocks of a wired network device and a wireless network device according to the present embodiment;

Fig. 3 is a diagram of a wired-wireless physical architecture of clock synchronization of the hybrid architecture provided in the present embodiment;

fig. 4 is a schematic structural diagram of a clock synchronization usage scenario of a cable-wireless hybrid TSN architecture according to the present embodiment;

Fig. 5 is a block diagram of a clock synchronization system of a wired-wireless hybrid TSN architecture according to an embodiment of the present application.

Reference numerals: 10. a PTP master device module; 20. PTP slave device modules; 30. a clock domain conversion module; 31. MTSN ethernet switches; 32. a physical hardware clock unit; 40. a cable domain TSN-PTP driving module; 50. a wireless network driving unit; 60. a wireless network modulation adjustment unit; 70. a first external terminal; 80. and a second external terminal.

Detailed Description

The application will be described in further detail below with reference to the drawings by means of specific embodiments. Wherein like elements in different embodiments are numbered alike in association. In the following embodiments, numerous specific details are set forth in order to provide a better understanding of the present application. However, one skilled in the art will readily recognize that some of the features may be omitted, or replaced by other elements, materials, or methods in different situations. In some instances, related operations of the present application have not been shown or described in the specification in order to avoid obscuring the core portions of the present application, and may be unnecessary to persons skilled in the art from a detailed description of the related operations, which may be presented in the description and general knowledge of one skilled in the art.

Furthermore, the described features, operations, or characteristics of the description may be combined in any suitable manner in various embodiments. Also, various steps or acts in the method descriptions may be interchanged or modified in a manner apparent to those of ordinary skill in the art. Thus, the various orders in the description and drawings are for clarity of description of only certain embodiments, and are not meant to be required orders unless otherwise indicated.

The numbering of the components itself, e.g. "first", "second", etc., is used herein merely to distinguish between the described objects and does not have any sequential or technical meaning. The term "coupled" as used herein includes both direct and indirect coupling (coupling), unless otherwise indicated.

Although hybrid TSNs may be the future of industrial communications, there are currently few analysis of the problems of clock synchronization transitions between ethernet TSNs, the mainstream wireless technologies 802.11 and 5G, and lack of practical implementation and measurement of clock synchronization transitions between the wire-domain and wireless domains. In view of this, the present inventors propose a method and system for clock synchronization of a hybrid wired-wireless architecture. In the application, the requirement of the intelligent automobile is considered at the beginning of 5G design, V2X is a part of a 5G network, and a special technology for short-range communication of the automobile is created. As shown in fig. 4, a simple schematic diagram of a vehicle-end hybrid TSN architecture is shown, in the driving process, a V2X device carried by a vehicle-end can interact with a 5G-V2X device with intelligent road at any time, and the vehicle-end hybrid TSN architecture is used to complete time synchronization of a wireless domain and a wired domain, so as to construct a vehicle-road cooperative system.

As shown in fig. 1, the clock synchronization method of the wired-wireless hybrid TSN architecture provided in this embodiment includes the following steps:

Step 100: PTP slave module 20 acquires reference clock information of the GMC highest level clock, including reference time stamp information; and calibrating the clock information according to the reference time stamp information, generating synchronous clock information according to the calibrated clock information, and transmitting the synchronous time stamp information in the synchronous clock information to the clock domain conversion module 30.

Specifically, in actual use, as shown in connection with fig. 3, the PTP protocol (precision time protocol) is a protocol for synchronizing device clocks in a computer network. In PTP, the master device module and the slave device module play different roles. The master device module is responsible for initiating a time synchronization operation by sending a time synchronization message to the slave device module. The master device module is typically a time server or a base station in the network and is configured to receive satellite signals and transmit the satellite signals to the PTP slave device module 20, wherein data information in the satellite signals is provided with TSN time stamps, and therefore, when the PTP master device module 10 transmits satellite signals to the PTP slave device module 20, the satellite signals need to be provided with the TSN time stamps, and therefore, the PTP master device module 10 transmits a time synchronization message to the PTP slave device module 20 for time synchronization operation by the PTP slave device module 20.

At this time, the PTP slave module 20 acquires the reference clock information of the GMC highest level clock after receiving the time synchronization message, and then calibrates its own clock according to the reference time stamp information in the reference clock signal. It relies on the timestamp information provided by the GMC's highest level clock to adjust its own clock, generating synchronized clock information to ensure that all devices in the network have consistent time.

Step 200: the clock domain conversion module 30 transmits the synchronization timestamp information in a wireless manner and a wired manner so that the first external terminal 70, which receives the synchronization timestamp information in a wireless manner, and the second external terminal 80, which receives the synchronization timestamp information in a wired manner, can perform clock synchronization according to the synchronization timestamp information.

The main element of the hybrid architecture of the present embodiment is a clock domain conversion module 30 for providing a connection between the wired and wireless domains to achieve clock synchronization between the wired and wireless domains. Specifically, the clock domain conversion module 30 sends out the synchronization timestamp information in a wireless manner (for example, through an 802.11 wireless network), so that the first external terminal 70 that receives the synchronization timestamp information in a wireless manner can perform clock synchronization according to the synchronization timestamp information; the clock domain switching module 30 issues the synchronization timestamp information in a wired manner (e.g., an ethernet TSN) so that the second external terminal 80, which receives the synchronization timestamp information in a wired manner, can perform clock synchronization according to the synchronization timestamp information. As shown in fig. 3, the first external terminal 70 may be a device (such as a road side 5G-V2X device) that emits a radio frequency signal RF, and the second external terminal 80 may be an ethernet wired Network Eth TSN Network device (such as a vehicle side V2X device).

The embodiment provides design and implementation of a hardware/software (HW/SW) network architecture with wired-wireless support, and by adopting the clock synchronization method of the application, the external terminal of the wired network and the external terminal of the wireless network can keep high-precision clock synchronization, so that high-performance clock synchronization conversion between the wired network and the wireless network is possible. In addition, the hybrid TSN of the embodiment has the remarkable advantages of being high in flexibility and low in debugging cost. Seamless interoperability of different devices can be achieved whether wired or wireless interfaces are used.

In this embodiment, as shown in fig. 2, the clock domain conversion module 30 includes MTSN ethernet switch 31 and physical hardware clock unit 32, and the clock domain conversion module 30 sends out the synchronous timestamp information in a wireless manner and a wired manner, which specifically includes the following steps:

Step 201: the PTP time synchronization protocol of synchronizing clock information is integrated into the time sensitive network by a wire domain TSN-PTP driver module 40.

Step 202: the synchronized clock information is transmitted to the physical hardware clock module through MTSN ethernet switch 31.

Step 203: and synchronizing clock information of the physical hardware clock module according to the synchronous clock information so that the physical hardware clock module can send out synchronous timestamp information in a wireless mode and a wired mode.

In this embodiment, specifically, after calibrating the clock of the PTP slave device module 20, the PTP slave device module 20 sends out synchronous clock information, and the PTP time synchronization protocol of the synchronous clock information is integrated into the time sensitive network through the cable domain TSN-PTP driver module 40, so that the interface of the ethernet switch 31 can support PTP (precise time protocol), and then the synchronous clock information can be transmitted to the physical hardware clock module through the MTSN ethernet switch 31 (MTSN SWITCH). After receiving the synchronous clock information, the physical hardware clock module synchronizes the clock information of the physical hardware clock module according to the synchronous clock information, so that the physical hardware clock module sends out synchronous timestamp information in a wireless mode and a wired mode.

Wherein, MTSN SWITCH of the IP is driven by a digital clock source with the frequency of 125MHz, and the physical hardware clock module PHC is driven by a clock.

In this embodiment, the wireless domain network module includes a wireless network driving unit 50 and a wireless network modulation adjusting unit 60, and the physical hardware clock module wirelessly transmits the synchronization timestamp information, and then includes:

the interface of the wireless network modulation adjustment unit 60 is configured by the wireless network driving unit 50 so that the interface supports the PTP protocol.

The synchronization time stamp information is shared to the first external terminal 70 through the wireless network modulation adjustment unit 60.

In this embodiment, specifically, after the physical hardware clock module issues the synchronization timestamp information, since the 802.11 modulation regulator (i.e. the wireless network modulation regulating unit 60) IP is driven by the digital clock source with 160MHz frequency, its time counter is not directly propagated to the 802.11 modulation regulator, so the PHC time counter must be output to the 802.11 modulation regulator, the interface of the wireless network modulation regulating unit 60 is configured by the wireless network driving unit 50 so that the interface can support the PTP protocol, and then the synchronization timestamp information is received by the wireless network modulation regulating unit 60 and shared to the first external terminal 70.

Furthermore, it should be noted that the time stamping process is performed by IP directly in hardware (including the wireless network modulation adjustment unit 60 and MTSN ethernet switch 31), and these time stamps are transmitted to two PTP (precision time protocol) daemons using Linux (operating system) kernel network interfaces. In addition, PHC time operation is commanded through the Linux kernel PTP interface. These operations are used to acquire/set the time and frequency drift of the PHC.

As an implementation manner of this embodiment, after integrating the PTP time synchronization protocol of the synchronization clock information into the time sensitive network by the cable domain TSN-PTP driver module 40, the method further includes: the synchronizing clock information is transmitted to the second external terminal 80 through the ethernet switch 31.

In practical application, as shown in fig. 3, MTSN ethernet switch 31 is a multiport ethernet switch. After integrating the PTP time synchronization protocol of the synchronization clock information into the time sensitive network by the cable domain TSN-PTP driver module 40, the MTSN ethernet switch 31 is also capable of directly transmitting the synchronization clock information to the second external terminal 80, keeping the clock of the second external terminal 80 consistent with the clock of the first external terminal 70.

As an implementation manner of this embodiment, after the clock domain conversion module 30 issues the synchronous timestamp information, the method further includes: the clock domain crossing circuit performs frequency division processing on the synchronous timestamp information to obtain stable synchronous timestamp information, so that the clock domain conversion module 30 sends out the stable synchronous timestamp information.

Specifically, the physical hardware clock module, the MTSN ethernet switch 31 and the wireless network modulation adjustment unit 60 of the present embodiment are 40MHz sources driven by the same oscillator, but the generality is not lost. Assuming that the clocks and clocks are asynchronous, in order to read the physical hardware clock PHC timer counter value from different digital clock domains, a Clock Domain Crossing (CDC) circuit is required to avoid metastability problems. The clock domain crossing circuit reduces the probability of metastable situations. The clock synchronization circuit of the system keeps the data from the source stable for several target clock cycles, thereby ensuring proper sampling of the source data. In this special case (i.e., metastable case), the circuit allows the TSN PHC to be read from the 802.11 modem side, where the circuit requires the clock source frequency to be at least one quarter of the target frequency. Thus, in the CDC circuit, the original PHC time locally generated at 125MHz is downsampled to 31.25MHz.

As shown in fig. 5, the clock synchronization system of the wired-wireless hybrid TSN architecture provided in this embodiment includes a PTP slave module 20 and a clock domain conversion module 30. The PTP slave device module 20 is configured to obtain reference clock information of a GMC highest level clock, where the reference clock information includes reference timestamp information; calibrating the clock information according to the reference time stamp information, generating synchronous clock information according to the calibrated clock information, and transmitting the synchronous time stamp information in the synchronous clock information to the clock domain conversion module 30; the clock domain conversion module 30 is configured to send out the synchronization timestamp information wirelessly and in a wired manner, so that the first external terminal 70 that receives the synchronization timestamp information wirelessly and the second external terminal 80 that receives the synchronization timestamp information in a wired manner can perform clock synchronization according to the synchronization timestamp information.

The clock synchronization system of the hybrid architecture in this embodiment specifically includes the PTP master device module 10, the PTP slave device module 20, and the clock domain conversion module 30, and in view of the fact that the modules are described in detail in the above-described clock synchronization method embodiment of the hybrid architecture, the embodiment is not described herein in detail.

In this embodiment, the clock domain conversion module 30 includes MTSN ethernet switches 31 and a physical hardware clock unit 32; the clock domain conversion module 30 issues the synchronous timestamp information wirelessly and wiredly, including:

Integrating a PTP time synchronization protocol for synchronizing clock information into a time sensitive network through a wire domain TSN-PTP driving module 40;

transmitting the synchronous clock information to the physical hardware clock module through MTSN ethernet switch 31;

And synchronizing clock information of the physical hardware clock module according to the synchronous clock information so that the physical hardware clock module can send out synchronous timestamp information in a wireless mode and a wired mode.

Specifically, after calibrating the clock of the PTP slave device module 20, the PTP slave device module 20 sends out synchronous clock information, and the PTP time synchronization protocol of the synchronous clock information is integrated into the time sensitive network through the cable domain TSN-PTP driver module 40, so that the interface of the ethernet switch 31 can support PTP (precision time protocol), and then the synchronous clock information can be transmitted to the physical hardware clock module through the MTSN ethernet switch 31 (MTSN SWITCH). After receiving the synchronous clock information, the physical hardware clock module synchronizes the clock information of the physical hardware clock module according to the synchronous clock information, so that the physical hardware clock module sends out synchronous timestamp information in a wireless mode and a wired mode.

The interface of the wireless network modulation adjustment unit 60 is configured by the wireless network driving unit 50 so that the interface supports PTP protocol;

Specifically, after the physical hardware clock module issues the synchronization time stamp information, since the 802.11 modulation regulator (i.e., the wireless network modulation regulating unit 60) IP is driven by the digital clock source of 160MHz frequency, its time counter is not directly propagated to the 802.11 modulation regulator, and thus the PHC time counter must be outputted to the 802.11 modulation regulator, the interface of the wireless network modulation regulating unit 60 is configured by the wireless network driving unit 50 so that the interface can support the PTP protocol, and then the synchronization time stamp information is received by the wireless network modulation regulating unit 60 and shared to the first external terminal 70.

In the clock domain conversion module 30 of the present embodiment, after integrating the PTP time synchronization protocol for synchronizing clock information into the time sensitive network by the cable domain TSN-PTP driving module 40, the clock domain conversion module further includes: the synchronizing clock information is transmitted to the second external terminal 80 through the ethernet switch 31.

The computer readable storage medium provided in this embodiment stores a program, which can be executed by a processor to implement the clock synchronization method of the hybrid architecture described above, and the detailed description of the clock synchronization method of the hybrid architecture is omitted herein.

Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by a computer program. When all or part of the functions in the above embodiments are implemented by means of a computer program, the program may be stored in a computer readable storage medium, and the storage medium may include: read-only memory, random access memory, magnetic disk, optical disk, hard disk, etc., and the program is executed by a computer to realize the above-mentioned functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above can be realized. In addition, when all or part of the functions in the above embodiments are implemented by means of a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a removable hard disk, and the program in the above embodiments may be implemented by downloading or copying the program into a memory of a local device or updating a version of a system of the local device, and when the program in the memory is executed by a processor.

The foregoing description of the invention has been presented for purposes of illustration and description, and is not intended to be limiting. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art to which the invention pertains, based on the idea of the invention.

Claims

1. A method for clock synchronization of a hybrid wire-wireless TSN architecture, comprising:

2. The clock synchronization method of claim 1, wherein the clock domain conversion module comprises MTSN ethernet switches and a physical hardware clock unit, the clock domain conversion module wirelessly and wiredly issuing the synchronization timestamp information, comprising:

Integrating a PTP time synchronization protocol of the synchronous clock information into a time sensitive network through a cable domain TSN-PTP driving module;

3. The clock synchronization method as claimed in claim 2, wherein the wireless domain network module includes a wireless network driving unit and a wireless network modulation adjusting unit, and the physical hardware clock module wirelessly transmits the synchronization timestamp information, and then includes:

4. The clock synchronization method of claim 2, wherein after integrating the PTP time synchronization protocol of the synchronized clock information into a time sensitive network by the wire domain TSN-PTP driver module, further comprising:

5. The clock synchronization method of claim 1, wherein after the clock domain conversion module issues the synchronization timestamp information, further comprising:

6. A clock synchronization system of a hybrid wired-wireless TSN architecture, comprising:

7. The clock synchronization system of claim 6, wherein the clock domain conversion module comprises MTSN ethernet switches and a physical hardware clock unit; the clock domain conversion module sends out the synchronous timestamp information in a wireless mode and a wired mode, and the clock domain conversion module comprises the following components:

8. The clock synchronization system of claim 7, wherein the wireless domain network module includes a wireless network driving unit and a wireless network modulation adjusting unit, and the physical hardware clock module wirelessly transmits the synchronization timestamp information, and then comprises:

9. The clock synchronization system of claim 7, wherein the clock domain conversion module, after integrating the PTP time synchronization protocol of the synchronized clock information into a time sensitive network by the wired domain TSN-PTP driver module, further comprises:

10. A computer readable storage medium, characterized in that the medium has stored thereon a program, which is executable by a processor to implement the method of any of claims 1-5.