Long-distance OTN link time synchronization performance physical simulation system

Abstract

The invention relates to the technical field of optical network time synchronization, in particular to a long-distance OTN link time synchronization performance physical simulation system, which simulates a long-distance OTN all-optical transmission effect consisting of a plurality of ROADMs by adopting a DWDM (Discrete Wavelength Division Multiplexing) optical wavelength conversion and wavelength switching technology and combining an optical fiber link temperature change simulation technology. Establishing a physical simulation system of a highly-simulated long-distance OTN backbone transmission link; and the master clock, the plurality of boundary clocks and the slave clocks are respectively accessed to each optical wavelength conversion and exchange unit, so that each clock device continuously circulates in the ring network, a chain-shaped step-by-step time synchronization system is formed, and time frequency synchronization of all the boundary clocks and the slave clocks is realized. The influence of each unit of the actual OTN link on the synchronization performance of the multi-stage time synchronization system can be accurately simulated to the greatest extent without a large number of complex ROADM equipment and a large number of optical fibers. Therefore, the problem that an existing software simulation model is low in simulation result precision is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical network time synchronization, and particularly to a physical simulation system for the time synchronization performance of a long-distance OTN link. Background Art

[0002] With the wide application of high-precision time synchronization technology, the demand for long-distance time synchronization through the OTN link of the optical fiber backbone network is increasing day by day. How to accurately simulate and evaluate the synchronization performance before the construction of the synchronization link is crucial. In an actual long-distance optical fiber link, the synchronization performance is affected by various factors, such as the fiber span, link temperature, total transmission distance, and number of synchronization node hops. The above factors will all lead to an increase in the time synchronization error, thereby degrading the synchronization performance.

[0003] At present, the evaluation of the time synchronization performance of a long-distance OTN link still depends on the measurement after the deployment of the time network, which has problems such as high cost, long cycle, and difficulty in covering complex scenarios. The existing software simulation models are too simplified and difficult to accurately simulate the influence of multi-factor coupling in the real link, resulting in a large difference between the simulation results and the actual situation.

[0004] Therefore, there is an urgent need for a simulation evaluation system that can quickly and accurately simulate the time synchronization performance of a long-distance OTN link and provide a basis and support for the construction of the long-distance OTN link time synchronization system. Summary of the Invention

[0005] The purpose of the present invention is to provide a physical simulation system for the time synchronization performance of a long-distance OTN link, aiming to solve the problem of low accuracy of the simulation results of the existing software simulation models.

[0006] To achieve the above purpose, the present invention provides a physical simulation system for the time synchronization performance of a long-distance OTN link, including a time-frequency reference, a master clock, a plurality of boundary clocks, slave clocks, a plurality of optical wavelength conversion and switching units, a plurality of temperature control boxes, a plurality of single-mode optical fibers, and a test unit;

[0007] The time-frequency reference is used to provide a time-frequency reference signal to the master clock and the test unit;

[0008] The master clock is used to receive an external time-frequency reference signal and communicate with the slave port of the boundary clock through the master port to achieve the time-frequency synchronization of the boundary clock;

[0009] A plurality of the boundary clocks are used to connect to the master clock or the upper-level boundary clock through the slave port to achieve local time-frequency synchronization and output the measured time-frequency signal; their master ports are connected to the lower-level boundary clock or the slave clock to achieve the time-frequency synchronization of the lower-level boundary clock or the slave clock;

[0010] The slave clock is used to connect to the upper-level boundary clock, achieve local time and frequency synchronization, and output the time and frequency signal to be measured;

[0011] Multiple optical wavelength conversion and switching units are used to simulate the dynamic reconfigurable optical add-drop multiplexer in the OTN link and simulate its all-optical switching and optical amplification effects;

[0012] Multiple temperature control boxes are used to store multiple single-mode optical fibers, and the temperature change of the optical fiber link is achieved by adjusting the temperature inside the box;

[0013] Multiple single-mode optical fibers are used to simulate the long-distance optical fiber link of the OTN network and are connected in series by multiple bare fiber reels;

[0014] The test unit receives an external time and frequency reference signal and measures the synchronization performance of the time and frequency signal to be measured with this as a reference.

[0015] Among them, the wavelength after conversion by the optical wavelength conversion and switching unit is a C-band wavelength, the wavelength interval is variable, supporting intervals of 25 GHz / 50 GHz / 100 GHz, and it can be adjusted between different line directions as needed.

[0016] Among them, the length of the single-mode optical fiber is adjustable, and the longest supports 100 km.

[0017] Among them, the synchronization performance measured by the test unit includes 1PPS time synchronization accuracy, 1PPS time synchronization stability, 10 MHz frequency stability, and 10 MHz frequency phase noise.

[0018] Among them, the wavelength switching function of the optical wavelength conversion and switching unit includes multiplexing the DWDM optical signals input and converted by the main ports of each clock device and outputting them from the line direction; multiplexing the DWDM optical signals input and converted by the slave ports of each clock device and outputting them from another line direction.

[0019] A physical simulation system for the time synchronization performance of a long - distance OTN link according to the present invention includes a time - frequency reference, a master clock, multiple boundary clocks, slave clocks, multiple optical wavelength conversion and switching units, multiple temperature control boxes, multiple single - mode optical fibers, and a test unit. The present invention adopts DWDM optical wavelength conversion and wavelength switching technology, combined with the optical fiber link temperature change simulation technology, to simulate the long - distance OTN all - optical transmission effect composed of multiple ROADMs, and establish a physical simulation system for highly simulating the long - distance OTN backbone transmission link. The master clock, multiple boundary clocks, and slave clocks are respectively connected to each optical wavelength conversion and switching unit, so that each clock device continuously circulates in the ring network, forming a chain - like step - by - step time synchronization system to achieve the time - frequency synchronization of all boundary clocks and slave clocks. The present invention is constructed by physical devices, and without a large number of complex ROADM devices and a large number of optical fibers, it can most accurately simulate the influence of each unit of the actual OTN link on the synchronization performance of the multi - level time synchronization system. Thus, it solves the problem that the simulation results of the existing software simulation models have low accuracy. Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 It is a schematic diagram of a physical simulation system for the time synchronization performance of a long - distance OTN link provided by the present invention.

[0022] In the figure: 1 - time - frequency reference, 2 - master clock, 3 - slave clock, 4 - test unit, 5 - boundary clock one, 6 - boundary clock two, 7 - boundary clock three, 8 - boundary clock four, 9 - optical wavelength conversion and switching unit one, 10 - optical wavelength conversion and switching unit two, 11 - optical wavelength conversion and switching unit three, 12 - temperature control box one, 13 - temperature control box two, 14 - temperature control box three, 15 - single - mode optical fiber one, 16 - single - mode optical fiber two, 17 - single - mode optical fiber three, 18 - boundary clock five. Detailed Embodiments

[0023] The following will describe in detail the embodiments of the present invention. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation of the present invention.

[0024] Please refer to Figure 1, the present invention provides a physical simulation system for the time synchronization performance of a long-distance OTN link, including a time-frequency reference 1, a master clock 2, multiple boundary clocks, a slave clock 3, multiple optical wavelength conversion and switching units, multiple temperature control boxes, multiple single-mode optical fibers, and a test unit 4;

[0025] The time-frequency reference 1 is used to provide a time-frequency reference signal to the master clock 2 and the test unit 4;

[0026] The master clock 2 is used to receive an external time-frequency reference signal and communicate with the slave port of the boundary clock through the master port to achieve the time-frequency synchronization of the boundary clock;

[0027] Multiple said boundary clocks are used to connect to the master clock 2 or the previous-level boundary clock through the slave port to achieve local time-frequency synchronization and output the measured time-frequency signal; their master ports are connected to the next-level boundary clock or the slave clock 3 to achieve the time-frequency synchronization of the next-level boundary clock or the slave clock 3;

[0028] The slave clock 3 is used to connect to the previous-level boundary clock to achieve local time-frequency synchronization and output the measured time-frequency signal;

[0029] Multiple said optical wavelength conversion and switching units are used to simulate the dynamic reconfigurable optical add-drop multiplexer in the OTN link and simulate its all-optical switching and optical amplification effects;

[0030] Multiple said temperature control boxes are used to store multiple single-mode optical fibers and realize the temperature change of the optical fiber link by adjusting the temperature inside the box;

[0031] Multiple said single-mode optical fibers are used to simulate the long-distance optical fiber link of the OTN network and are connected in series by multiple bare fiber reels;

[0032] The test unit 4 receives an external time-frequency reference signal and, taking this as a reference, measures the synchronization performance of the measured time-frequency signal.

[0033] Further, the wavelength after conversion by the optical wavelength conversion and switching unit is a C-band wavelength, the wavelength interval is variable, supporting intervals of 25 GHz / 50 GHz / 100 GHz, and it can be adjusted between different line directions as needed.

[0034] Further, the length of the single-mode optical fiber is adjustable, with a maximum support of 100 km.

[0035] The synchronization performance measured by the test unit 4 includes the 1PPS time synchronization accuracy, the 1PPS time synchronization stability, the 10 MHz frequency stability, and the 10 MHz frequency phase noise.

[0036] Further, the wavelength exchange function of the optical wavelength conversion and exchange unit includes multiplexing the DWDM optical signals input and converted by the main ports of each clock device and outputting them in the line direction; multiplexing the DWDM optical signals input and converted by the slave ports of each clock device and outputting them in another line direction.

[0037] In this embodiment, a plurality of the boundary clocks are composed of boundary clock one 5, boundary clock two 6, boundary clock three 7, boundary clock four 8 to boundary clock N + 2. The number of the boundary clocks is determined according to actual requirements. The plurality of optical wavelength conversion and exchange units are respectively optical wavelength conversion and exchange unit one 9, optical wavelength conversion and exchange unit two 10, and optical wavelength conversion and exchange unit three 11; the DWDM wavelengths used by the optical wavelength conversion and exchange unit one 9, the optical wavelength conversion and exchange unit two 10, and the optical wavelength conversion and exchange unit three 11 are all different; the plurality of temperature control boxes are respectively temperature control box one 12, temperature control box two 13, and temperature control box three 14; the plurality of single-mode optical fibers are respectively single-mode optical fiber one 15, single-mode optical fiber two 16, and single-mode optical fiber three 17;

[0038] The time-frequency reference 1 serves as the time-frequency reference source of the entire simulation system and outputs two groups of time-frequency reference 1 signals. The time-frequency reference 1 signal 1 is sent to the master clock 2, and the time-frequency reference 1 signal 2 is sent to the test unit 4; each group of time-frequency reference 1 signals usually includes at least a 1PPS synchronous second signal and a 10MHz sine signal.

[0039] The test unit 4 receives the time-frequency reference 1 signal 2 sent by the time-frequency reference 1 and uses it as the reference source; at the same time, it can receive the measured time-frequency signals output by the boundary clock and the slave clock 3 according to needs, and measure the synchronization performance of the measured time-frequency signals, usually including 1PPS time synchronization accuracy, 1PPS time synchronization stability, 10MHz frequency stability, and 10MHz frequency phase noise.

[0040] The master clock 2 receives external time-frequency reference signals, usually including at least a 1PPS synchronous second signal and a 10MHz sine signal, and realizes local synchronization with the time-frequency reference 1; its main port is connected to the optical wavelength conversion and exchange unit one 9. After wavelength conversion and exchange, it communicates with the slave port of the boundary clock one 5 connected to the optical wavelength conversion and exchange unit two 10, and bidirectionally transmits synchronization information to realize the time-frequency synchronization of the boundary clock one 5 with the master clock 2.

[0041] The single-mode optical fiber one 15 is used to simulate the long-distance optical fiber link of the OTN network and connects the line direction 2 of the optical wavelength conversion and exchange unit one 9 and the line direction 1 of the optical wavelength conversion and exchange unit two 10; it is two independent single-mode optical fiber links, and each link is connected in series with a plurality of bare fiber reels.

[0042] The single-mode optical fiber two 16 is used to simulate a long-distance optical fiber link of an OTN network, and is connected to the line direction 2 of the optical wavelength conversion and switching unit two 10 and the line direction 1 of the optical wavelength conversion and switching unit three 11; it is two independent single-mode optical fiber links, and each link is connected in series with multiple bare fiber reels.

[0043] The single-mode optical fiber three 17 is used to simulate a long-distance optical fiber link of an OTN network, and is connected to the line direction 2 of the optical wavelength conversion and switching unit three 11 and the line direction 1 of the optical wavelength conversion and switching unit one 9; it is two independent single-mode optical fiber links, and each link is connected in series with multiple bare fiber reels.

[0044] The temperature control box one 12 is used to store the single-mode optical fiber one 15 (bare fiber reel), and by adjusting the temperature inside the box, the temperature change of the single-mode optical fiber is realized.

[0045] The temperature control box two 13 is used to store the single-mode optical fiber two 16 (bare fiber reel), and by adjusting the temperature inside the box, the temperature change of the single-mode optical fiber is realized.

[0046] The temperature control box three 14 is used to store the single-mode optical fiber three 17 (bare fiber reel), and by adjusting the temperature inside the box, the temperature change of the single-mode optical fiber is realized.

[0047] The boundary clock one 5, its slave port is connected to the optical wavelength conversion and switching unit two 10, after wavelength conversion and switching, it communicates with the master port of the master clock 2 connected to the optical wavelength conversion and switching unit one 9, and synchronizes information bidirectionally to realize local time-frequency synchronization and output the measured time-frequency signal 1; its master port is connected to the optical wavelength conversion and switching unit two 10, after wavelength conversion and switching, it communicates with the slave port of the boundary clock two 6 connected to the optical wavelength conversion and switching unit three 11, and synchronizes information bidirectionally to realize the time-frequency synchronization of the boundary clock two 6.

[0048] The boundary clock two 6, its slave port is connected to the optical wavelength conversion and switching unit three 11, after wavelength conversion and switching, it communicates with the master port of the boundary clock one 5 connected to the optical wavelength conversion and switching unit two 10, and synchronizes information bidirectionally to realize local time-frequency synchronization and output the measured time-frequency signal 2; its master port is connected to the optical wavelength conversion and switching unit three 11, after wavelength conversion and switching, it communicates with the slave port of the boundary clock three 7 connected to the optical wavelength conversion and switching unit one 9, and synchronizes information bidirectionally to realize the time-frequency synchronization of the boundary clock three 7.

[0049] The boundary clock three 7 is connected to the optical wavelength conversion and switching unit one 9 through its slave port. After wavelength conversion and switching, it communicates with the master port of the boundary clock two 6 connected to the optical wavelength conversion and switching unit three 11, bi-directionally transmitting synchronization information to achieve local time-frequency synchronization and output the measured time-frequency signal 3. Its master port is connected to the optical wavelength conversion and switching unit one 9. After wavelength conversion and switching, it communicates with the slave port of the boundary clock four 8 connected to the optical wavelength conversion and switching unit two 10, bi-directionally transmitting synchronization information to achieve the time-frequency synchronization of the boundary clock four 8.

[0050] According to the above rules, the slave port of the boundary clock n (2 ≤ n ≤ N + 1) is connected to the master port of the upper-level boundary clock n - 1 for communication, bi-directionally transmitting synchronization information to achieve local time-frequency synchronization and output the measured time-frequency signal n. The master port of the boundary clock n is connected to the slave port of the lower-level boundary clock N + 1 for communication, bi-directionally transmitting synchronization information to achieve the time-frequency synchronization of the boundary clock N + 1.

[0051] The slave clock 3 is connected to the optical wavelength conversion and switching unit two 10 through its slave port. After wavelength conversion and switching, it communicates with the master port of the boundary clock N + 2 connected to the optical wavelength conversion and switching unit one 9, bi-directionally transmitting synchronization information to achieve local time-frequency synchronization and output the measured time-frequency signal S.

[0052] One end of the single-mode optical fiber one 15 is connected to the line direction 2 of the optical wavelength conversion and switching unit one 9, and one end of the single-mode optical fiber three 17 is connected to the line direction 1 of the optical wavelength conversion and switching unit one 9. Both the line direction 1 and the line direction 2 are two-way for both receiving and transmitting. In the user direction, an optical interface is used to connect to the master ports or slave ports of each device such as the master clock 2, the boundary clock three 7, …… the boundary clock N + 2.

[0053] Its wavelength conversion function is to receive the optical signals sent from the master ports or slave ports of each device such as the master clock 2, the boundary clock three 7, …… the boundary clock N + 2, and convert them into DWDM optical signals.

[0054] Its wavelength switching function is to multiplex the DWDM optical signals input from the master ports of each clock device and converted, and output them from the line direction 2; multiplex the DWDM optical signals input from the slave ends of each clock device and converted, and output them from the line direction 1; receive the DWDM optical signals input from the line direction 2, and perform switching and demultiplexing on them, and send each corresponding optical signal to the master ports of each clock device; receive the DWDM optical signals input from the line direction 1, and perform switching and demultiplexing on them, and send each corresponding optical signal to the slave ports of each clock device.

[0055] Similarly, for the second optical wavelength conversion and switching unit 10, line direction 1 is connected to one end of the single-mode optical fiber 15, and line direction 2 is connected to one end of the single-mode optical fiber 16. Both line direction 1 and line direction 2 are for both transmitting and receiving directions. The user direction is connected to the main ports or slave ports of each device such as the first boundary clock 5, …… the Nth boundary clock, and the slave clock 3 through optical interfaces.

[0056] Its wavelength conversion function is to receive the optical signals sent from the main ports or slave ports of each device such as the first boundary clock 5, …… the Nth boundary clock, and the slave clock 3, and convert them into DWDM optical signals.

[0057] Its wavelength switching function is to multiplex the DWDM optical signals input from the main ports of each clock device and converted, and output them from line direction 2; multiplex the DWDM optical signals input from the slave ends of each clock device and converted, and output them from line direction 1; receive the DWDM optical signals input from line direction 2, perform switching and demultiplexing on them, and send each corresponding optical signal to the main ports of each clock device; receive the DWDM optical signals input from line direction 1, perform switching and demultiplexing on them, and send each corresponding optical signal to the slave ports of each clock device.

[0058] Similarly, for the third optical wavelength conversion and switching unit 11, line direction 1 is connected to one end of the single-mode optical fiber 16, and line direction 2 is connected to one end of the single-mode optical fiber 17. Both line direction 1 and line direction 2 are for both transmitting and receiving directions. The user direction is connected to the main ports or slave ports of each device such as the second boundary clock 6, …… the (N + 1)th boundary clock through optical interfaces.

[0059] Its wavelength conversion function is to receive the optical signals sent from the main ports or slave ports of each device such as the second boundary clock 6, …… the (N + 1)th boundary clock, and convert them into DWDM optical signals.

[0060] Its wavelength switching function is to multiplex the DWDM optical signals input from the main ports of each clock device and converted, and output them from line direction 2; multiplex the DWDM optical signals input from the slave ends of each clock device and converted, and output them from line direction 1; receive the DWDM optical signals input from line direction 2, perform switching and demultiplexing on them, and send each corresponding optical signal to the main ports of each clock device; receive the DWDM optical signals input from line direction 1, perform switching and demultiplexing on them, and send each corresponding optical signal to the slave ports of each clock device.

[0061] What is disclosed above is only a preferred embodiment of a long-distance OTN link time synchronization performance physical simulation system of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A physical simulation system for the time synchronization performance of a long-distance OTN link, characterized in that it includes a time-frequency reference, a master clock, multiple boundary clocks, slave clocks, multiple optical wavelength conversion and switching units, multiple temperature control boxes, multiple single-mode optical fibers, and a test unit; the time-frequency reference is used to provide time-frequency reference signals to the master clock and the test unit; the master clock is used to receive external time-frequency reference signals and communicate with the slave ports of the boundary clocks through the master ports to achieve the time-frequency synchronization of the boundary clocks; multiple of the boundary clocks are used to connect to the master clock or the upper-level boundary clock through the slave ports to achieve local time-frequency synchronization and output the measured time-frequency signals; their master ports are connected to the lower-level boundary clocks or slave clocks to achieve the time-frequency synchronization of the lower-level boundary clocks or slave clocks; the slave clock is used to connect to the upper-level boundary clock to achieve local time-frequency synchronization and output the measured time-frequency signals; multiple of the optical wavelength conversion and switching units are used to simulate the dynamic reconfigurable optical add-drop multiplexer in the OTN link and simulate its all-optical switching and optical amplification effects; multiple of the temperature control boxes are used to store multiple single-mode optical fibers and realize the temperature change of the optical fiber link by adjusting the temperature inside the box; multiple of the single-mode optical fibers are used to simulate the long-distance optical fiber link of the OTN network and are connected in series with multiple bare fiber trays; the test unit receives external time-frequency reference signals and, taking this as a reference, measures the synchronization performance of the measured time-frequency signals.

2. The physical simulation system for the time synchronization performance of a long-distance OTN link according to claim 1, characterized in that the wavelength after conversion by the optical wavelength conversion and switching unit is a C-band wavelength, the wavelength interval is variable, supporting intervals of 25 GHz / 50 GHz / 100 GHz, and it can be adjusted between different line directions as needed.

3. The physical simulation system for the time synchronization performance of a long-distance OTN link according to claim 1, characterized in that the length of the single-mode optical fiber is adjustable, and the maximum length supported is 100 km.

4. The physical simulation system for the time synchronization performance of a long-distance OTN link according to claim 1, characterized in that the synchronization performance measured by the test unit includes 1PPS time synchronization accuracy, 1PPS time synchronization stability, 10 MHz frequency stability, and 10 MHz frequency phase noise.

5. The physical simulation system for the time synchronization performance of a long-distance OTN link according to claim 1, characterized in that the wavelength switching function of the optical wavelength conversion and switching unit includes multiplexing the DWDM optical signals input and converted by the master ports of each clock device and outputting them from the line direction; multiplexing the DWDM optical signals input and converted by the slave ports of each clock device and outputting them from another line direction.

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