CN106330374A - Optical fiber support network with unified time and frequency reference - Google Patents

Abstract

The invention discloses an optical fiber support network based on a unified time and frequency standard. The optical fiber support network comprises a time and frequency standard device, and a plurality of wavelength division multiplexing systems and a subsystem optical transmission network which can receive Lambda(ton) high-precision time and frequency standard pilots. The wavelength division multiplexing systems and the subsystem optical transmission network are relatively independent of the optical fiber of a unified time and frequency standard transmission channel. The time and frequency standard device provides a unified time and frequency standard for the wavelength division multiplexing systems and the subsystem optical transmission network connected therewith through a time and frequency standard transmission channel. The problem in the prior art that communication is not efficient and ultra-long-distance communication cannot be realized as the time and frequency standard of three support networks cannot be detected accurately is solved.

Description

Optical fiber support network with unified time and frequency reference

technical field

The invention belongs to the technical field of communication networks, and relates to an optical fiber support network, in particular to an optical fiber support network with a unified time and frequency reference.

Background technique

At present, the core of the terrestrial transmission network is the terrestrial optical fiber transmission network. my country has built an optical communication network with G.652 (about 95%) optical cables as the main body, and various communication service networks are formed through optical fiber transmission. Among them, three service resources are special: unified time frequency reference service support network, unified public channel signaling service support network and communication management service network. The above three networks are the supporting networks required by all communication systems such as wired communication, wireless communication, broadcast TV, smart grid, etc.

The mixed transmission channels of the traditional three supporting networks and the business communication network belong to "in-band transmission". The mutual interference between the supporting network and the service network cannot be isolated from each other due to "in-band transmission", which leads to the inefficiency of the entire communication. An important factor for high-speed and ultra-long-distance communication transmission.

And practice has proved that the inherent optical transmission characteristics of each optical fiber are inconsistent, and it is required to realize the time-frequency reference pilot of each optical fiber in each optical cable. Automatic real-time online accurate monitoring and automatic locking and equalization compensation control The "active discovery" function of ultra-long-distance, ultra-high-speed, and ultra-large-capacity transparent, stable, and robust optical transmission enables stable, reliable, mature and safe normal operation.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of the above-mentioned prior art, and provide an optical fiber support network device with a unified time and frequency reference. The invention solves the problem that the communication efficiency is not high and the ultra-long-distance communication cannot be performed due to the inability to accurately detect the time-frequency reference of the three supporting networks in the prior art.

The purpose of the present invention is achieved through the following technical solutions:

The optical fiber support network of this unified time frequency reference includes a time frequency reference device and several wavelength division multiplexing systems and subsystem optical transmission networks that can receive λton high-precision time frequency reference pilots; the wavelength division multiplexing systems and subsystems The system optical transmission network is relatively independent from the optical fiber of the unified time-frequency reference transmission channel; the time-frequency reference device provides a unified time-frequency reference for the wavelength division multiplexing system and subsystem optical transmission network connected to it through the time-frequency reference transmission channel .

Furthermore, the present invention is characterized in that:

Among them, the optical fiber adopts an optical support network composed of two single-fiber bidirectional CWDM or two single-fiber bidirectional DWDM. The optical support network realizes real-time online monitoring, automatic servo locking and precise control of equalization compensation for optical transmission delay.

Among them, the optical fiber adopts an optical support network composed of a single-fiber bidirectional CWDM or a single-fiber bidirectional DWDM. The optical support network realizes real-time online monitoring, automatic servo locking and precise control of equalization compensation for optical transmission delay.

Among them, the base station connected by optical fiber in the four-level master-slave mode of the optical support network is equipped with a micro-power transmitting unit of the satellite navigation system.

The time-frequency reference transmission channel and the optical monitoring channel in the optical fiber form a cellular optical strip.

Among them, the optical transmission network of the subsystem adopts WDM dual-fiber or WDM single-fiber transmission.

The time-frequency reference device is a cesium atomic clock.

Among them, the subsystem optical transmission network also has an intelligent optical routing controller.

The beneficial effects of the present invention are: using a unified time-frequency reference device to provide a unified time for each wavelength division multiplexing system and subsystem optical transmission network, which can meet the requirements of ultra-large capacity, ultra-long distance, and ultra-high speed, and the monitoring accuracy can also be improved ; The optical fiber of the wavelength division multiplexing system and the optical transmission network of the subsystem can be monitored in real time, and the fiber transmission optical path can be split and stripped due to the negative influence of the random noise of the delay change, and the slow change of the optical fiber delay can be accurately controlled; and the wavelength division multiplexing is unified. The optical monitoring accuracy of the optical transmission network of the system and subsystems; due to the high-precision time-frequency synchronization support system to monitor and control the uncertainty of the optical fiber transmission network, the dedicated optical monitoring channel is mainly used to monitor optical power and optical fiber attenuation aging and remote The distance automatic equalization control optical power constant or the long-distance intelligent automatic optical power stabilization technology can be realized stably and accurately.

Furthermore, the use of bidirectional or unidirectional CWDM or DWDM can reduce the negative impact introduced by random changes in the optical routing of the split and stripped optical transmission network; after filtering out these random noises, the master-slave synchronization accuracy of time and frequency is greatly improved. Further improvement can be achieved only by increasing the level of the main station high-level time and atomic time and only upgrading certain hardware units and system software of the system; no need to rebuild the infrastructure, that is, build the network on the original infrastructure .

Furthermore, the base station in the optical support network is equipped with a micro-power transmitting unit of the satellite navigation system, and the transmitting unit has the functions of satellite positioning, navigation and timing. The accuracy of the air interface on the base station and the air interface of the ground unit enables the intelligent and accurate positioning coordinates T (x, y, z) of the database and the ultra-precise timing accuracy to be provided to the air launch interface of the pseudolite launcher, which has achieved higher Accurate time-frequency reference signal.

Furthermore, using a cesium atomic clock with a 6 million-year accuracy of 1 second as a time-frequency reference device, the backbone network of the optical fiber transmission network is divided and stripped of various random noise changes in the optical fiber transmission optical route, and online monitoring, detection, remote control and Remote adjustment automatic locking and balance compensation correction, time and frequency synchronization accuracy can be further improved to 40ps/day 1.63ps/hour, time synchronization accuracy <1ns/day. The time and frequency reference of 6 million years with no difference of 1 second is used as the "level 0" master station loopback to detect the variation error of optical fiber transmission delay, which means that the delay variation drift and aging drift error of the divisible stripped optical fiber will be reduced to the threshold > 456.6ps /day, >19.02ps/1 hour random noise can be filtered out, then the effect of master-slave synchronization can be significantly improved. And the higher the time accuracy of the time-frequency reference device, the better the performance of the network.

detailed description

Below in conjunction with specific embodiment the present invention is described in further detail:

The invention provides an optical fiber support network with a unified time-frequency reference, including a time-frequency reference device that provides a unified reference time-frequency, the time-frequency reference device is a cesium atomic clock, and several wavelength division multiplexing systems and subsystems connected with the time-frequency reference device Optical transmission network; Subsystem Optical transmission network and wavelength division multiplexing system adopt optical fiber with optical monitoring channel and time frequency reference transmission channel, and the time frequency reference device sends the wavelength division multiplexing system and sub The system optical transmission network provides a unified time and frequency reference. The optical monitoring channel and the time-frequency reference transmission channel in the optical fiber used by the wavelength division multiplexing system and the subsystem optical transmission network form a cellular optical ribbon; and the wavelength division multiplexing system adopts dual fiber or single fiber transmission. In each optical fiber used in the wavelength division multiplexing system and subsystem optical transmission network, 1-2 bidirectional CWDM or 1-2 bidirectional DWDM are used to form an optical support network. The optical support network realizes real-time online monitoring and automatic monitoring of optical transmission delay. Lock and equalize compensation. The base stations connected by optical fibers in the four-level master-slave mode of the optical support network are equipped with micro-power transmitting units of the satellite navigation system.

The time-frequency reference device can also use the atomic clock of the National Time Service Center, commercial-grade atomic clocks and industrial-grade atomic clocks, such as strontium atomic clocks, cesium atomic clocks and hydrogen clocks.

The optical transmission network of the subsystem is divided according to the region, and the regional scope of a city, the regional scope of a county, etc. can be divided into the scope of a subsystem optical transmission network. The wavelength division multiplexing system and subsystem optical transmission network are built on the basis of the existing communication network, and a time-frequency reference device can also be set in areas with large geographical distances. Therefore, the optical fiber supporting network of the unified time-frequency reference of the present invention is formed by connecting several interconnected and synchronized time-frequency reference devices, and the wavelength division multiplexing system and subsystem optical transmission network connected with the corresponding time-frequency reference devices. .

In the present invention, the optical fiber used by the wavelength division multiplexing system and the subsystem optical transmission network has an optical monitoring channel λs and a time-frequency reference transmission channel λt; CWDM single-fiber bidirectional and DWDM single-fiber bidirectional modes are adopted, and a single fiber is in the O band 1310nm CWDM single-fiber bidirectional transmission two pairs of equal delay light wave pair +1450nm～1620nm, DWDM single uplink or single downlink broadband mixed transmission mode. That is to say: in this dedicated support network, λs selects 1510.00nm, and λt selects 1290.00nm and 1330.00nm (in DWDM, λt can select 1549.32nm and 1551.72nm or others), and the other optical wave bands are selected by special users to form together Unified service guarantee fiber support network platform. This dedicated supporting network platform includes ultra-precise cloud synchronization λt and λto1~λton time-frequency reference pilot, optical monitoring channel λs, new public channel signaling network No.7, network management network, and network security...etc. In order to make full use of this optical fiber, some special user private networks with high security requirements can also be added, such as dedicated military confidential communication channels and optical routing channels dedicated to transmitting national security confidential information; the comprehensive economic benefits of optical fiber resources are better .

The time-frequency reference device can use the cesium atomic clock of the National Time Service Center. The cesium atomic clock can reach 6 million years without a difference of 1 second. Its own aging drift is: ≤39.14ps/day, ≤1.63ps/1 hour, and its own aging drift A substantial increase. For our country to achieve higher precision, deeper segmentation and stripping ultra-slowly changing optical fiber delay change drift and aging drift, so that the random noise filtering ability of master-slave transmission is higher, and the ultra-precision time and frequency reference reference is in optical fiber transmission Transparent, accurate, stable, safe and robust transmission in the network > 2000km creates the most critical conditions for successful realization, this unified time-frequency reference fiber with the function of splitting and stripping the fiber with extremely slow-changing random noise The accuracy of the supporting network platform has also been greatly improved. As long as the software is upgraded or a few hardware units are changed, the synchronization accuracy of the four levels of time and frequency references in the country can be greatly improved.

After splitting and stripping the negative effects of random variations in optical fiber transmission delay, and unifying the time-frequency reference, the regenerated UTC time-frequency reference output from the slave station achieves delay difference ≈ 0, transmission delay drift ≈ 0, and transmission noise Transfer ≈ 0 A new time-frequency reference supply system with asymmetric delay difference ≈ 0 dispersion accumulation ≈ 0 for each output static cross combination pair of each optical fiber; effective filtering of negative effects brought by the inherent characteristics of optical fiber transmission Finally, the unified time and frequency reference optical fiber support network platform adopts special optical fiber transmission dual-fiber bidirectional or single-fiber bidirectional transmission, and realizes real-time optical fiber online monitoring and automatic locking and balance compensation control technology, and cleverly splits and strips the extremely slow fiber delay. Randomly changing noises are graded and filtered to achieve true master-slave time and ultra-precise time-frequency synchronization.

Due to the high-precision time-frequency synchronization support system to monitor and control the uncertainty of the optical fiber transmission network, the λs dedicated optical monitoring channel is mainly used to monitor optical power and optical fiber attenuation aging and long-distance automatic equalization control optical power constant or long-distance The intelligent automatic optical power stabilization technology can achieve stable and accurate realization.

The optical support network of the present invention is "six in and six out" cellular strip transmission, which is safe and reliable, that is, stable, safe and robust transmission measures are guaranteed. That is to say: the unified time and frequency reference optical fiber support network platform provides time and frequency services for various communication services except that it is a cloud optical fiber network, and completes cloud synchronization, cloud access, cloud transmission, cloud computing, and cloud multithreading at the same time. Work, after many random function controls are converted into a stable random process, real-time online monitoring and automatic loosely coupled frequency-locked phase-locked technology to a constant delay value.

The supporting network adopts intelligent equipment such as intelligent optical routing controllers, adopts wavelength division multiplexing, and adopts an integrated method to add other supporting network platforms to this optical fiber, that is, every direction in each direction of the optical fiber distribution frame The mode of occupying two optical fibers in one optical cable: it is difficult to provide wavelength division multiplexing of two optical fibers, and a series of multi-functional services can also be provided by using single-fiber bidirectional wavelength division multiplexing.

A unified time and frequency reference fiber support network platform + λs dedicated optical monitoring channel support management system equipment + signaling management and accurate automatic billing system equipment + λa + λc + ... and other small and medium-sized cellular optical band-shaped traditional one-service guarantee optical fiber support network platform; or a unified time and frequency reference optical fiber support network platform with a single fiber DWDM single-fiber two-way transmission using G.652 optical cable + λs dedicated optical monitoring channel support Management system equipment + signaling management system equipment + λa + λr + ... etc. constitute the unified service guarantee optical fiber support network platform of cellular strip optical transmission, which is one of the most fully utilized modes of optical fiber resources.

The design solution using G.653 optical fiber is as follows:

CWDM single-fiber bidirectional transmission mode: T (x, y, z, t, f, s, c, d, g...) control design specification: according to the attenuation and aging of G.652 optical fiber, the design of static cross transfer is reasonably established method. G.652 optical fiber cable fiber attenuation ≤ 0.3dB/km; select 1290nm and 1330nm delay difference 2 × 50km × 20 = 2000km optical transmission delay difference accumulation; 1290.00nm50km fiber delay value = 244774.6775ns; 1330.00nm50km Optical fiber delay value = 244774.6780ns; the relative error of the two waves depends on the error change value of the dispersion slope, we all know that the inherent dispersion slope of the optical fiber is generally 0.057ps/nm2.km～0.080ps/nm2.km similar to the optical band The dispersion slope difference is: △б is less than 0.001ps/nm2.km, and the dispersion accumulation of 50km fiber is also <1.5ps. Therefore, after adopting equal delay light wave + 2×50km static cross-transmission of 2000km fiber bidirectionally transmitted light wave pair adaptive equalization compensation, (For example, 1290.00nm and 1330.00nm) The accumulation of time delay asymmetry difference of the static cross transmission of two light wave groups for 2000km transmission is ≈0.

DWDM single-fiber bidirectional transmission mode: T (x, y, z, t, f, s, c, d, g...) control design specification: according to the attenuation and aging of G.652 optical fiber, the design of static cross transmission is reasonably established method. 2×100km×10=2000km delay difference accumulation ≤50ps; take 1550.52nm, 2×100km delay value 2×489761.950ns=979523.900ns as the center reference wave 1551.32nm100km delay value 489763.271ns and 1549.72nm100km delay value 489760.630ns static cross transfer 2×100km delay value 979523.901ns, 2×100km×10=2000km delay difference accumulation=10ps, λ group pair 2000km transmission delay asymmetric difference ≈0. Slow drift swing 2×100km is ±1.321ns, 2×20km is ±0.264ns. The method of comprehensive utilization of other optical fiber resources in the intelligent optical network in each G.652 optical cable: use the λto provided by the unified time and frequency reference optical fiber support network platform to monitor and automatically lock and balance each optical fiber in each optical cable on-line in real time rear.

The design solution using G.653 optical fiber is as follows:

Choose one fiber in each G.653 fiber optic cable to establish a dedicated single-fiber bidirectional transmission unified time and frequency reference fiber support network platform:

DWDM single-fiber bidirectional transmission mode: equal delay with 1550.00nm as zero dispersion center, such as equal delay between 1551.72nm and 1549.32nm (relative error of equal delay <10ps) Static crossover control design specification: with 1550.12nm as zero dispersion center The ±30nm of the nominal reference wave is based on the quadratic law of the inherent transmission characteristics of the G.653 optical cable. There are light wave pairs with a very small difference in optical transmission delay. Equal time delay pair +2×100km×10=2000km DWDM single-fiber bidirectional optical transmission time delay asymmetry difference ≈0, time delay drift swing ≈0, 2000km dispersion accumulation ≈0. This is the technical effect achieved by the differential group delay symmetry control transfer technology.

DWDM is divided into several subsystems according to S (1450nm ~ 1530nm), C (1530nm ~ 1560nm), L (1565nm ~ 1625nm) bands, single fiber downlink (or uplink) transmission mode: 100km optical attenuation of each other fiber of this cable The amplified output power of 25dB/100km laser is 10dBm, each fiber (downlink or uplink) time division filter or several subsystems adopt λto1, λto2...λton fiber real-time on-line monitoring and automatic locking and equalization compensation control design specifications. Taking 1544.92nm as the 100km fiber delay value in λto1 = 489752.728ns dispersion coefficient 16.24ps/nm.km, then 1543.73nm and 1546.12nm, 2 × 100km × 10 = 2000km optical transmission delay asymmetric difference ≈ 0, dispersion accumulation ≈0; Txk=て selection of engineering design specification for large and medium cellular strip transfer mode: 100kmて is 500000.000ns T2k code, 200kmて is 1000000.000nsT1k code.

The design solution using G.655 optical fiber is as follows:

DWDM single-fiber bidirectional transmission mode: selection specification of zero dispersion displacement center light wave: T(x, y, z, t, f, s, c, d, g...). Txk = τ selection design specification; 2 × 200km × 5 = 2000km equal delay light wave with 1550.52nm as zero dispersion center or λto1 reference center static cross-transmission mode unified time and frequency reference fiber support network platform with 1530nm ~ 1560nm Subsystem fiber optic delivery system. DWDM is based on the subsystem of S-band (1450nm～1530nm) with λto1=1490.00nm as the center reference, the second subsystem of C-band (1530nm～1560nm) with _λto2 =1544.92nm as the center reference, and the L-band (1565nm～ 1625nm) with λto3=1584.95nm as the center reference, the third subsystem band is divided into three subsystems, statically crossed 2000km dual-fiber bidirectional, that is, single-fiber downlink or uplink transmission mode; _λto1 , _λto2 , _λto3 of the three subsystems _...... The three light waves use the unified time and frequency reference optical fiber to support the network platform to establish a precise time and frequency reference for real-time online monitoring and automatic locking and equalization compensation of the optical fiber based on the downlink or uplink. _to1 , λ _to2 , constant (random variation of split and stripped optical fiber transmission) adapt to the difference of the three groups 2×100km～2×50km～2×10km static crossing 2000km transmission The time delay difference accumulation with all value errors < 20ps is the dispersion accumulation < 20ps. The application of the high-precision time-frequency frequency reference pilot of the unified time-frequency reference optical fiber support network platform will give the inherent light wave of the optical fiber transmission optical route in the optical fiber transmission network.

Claims (8)

1. the fiber support network of frequency reference unified time, it is characterised in that include Time and frequency standard device and all can connect Receive several wavelength-division multiplex systems and the subsystem optical transport network of λ ton split-second precision frequency reference pilot tone；

Described wavelength-division multiplex system is relative with the optical fiber of subsystem optical transport network with frequency reference transmission unified time channel Independent；

Described Time and frequency standard device is connected wavelength-division multiplex system and son by Time and frequency standard transmission channel System optical transport network provides unified Time and frequency standard.

Unified time the most according to claim 1 frequency reference fiber support network, it is characterised in that described optical fiber is adopted With 2 single fiber bi-directional CWDM or the light supporting network of 2 single fiber bi-directional DWDM compositions, optical transport time delay is realized by light supporting network Real time on-line monitoring, automatic servo lock and accurately control isostatic compensation.

Unified time the most according to claim 1 frequency reference fiber support network, it is characterised in that described optical fiber is adopted With 1 single fiber bi-directional CWDM or the light supporting network of 1 single fiber bi-directional DWDM composition, optical transport time delay is realized by light supporting network Real time on-line monitoring, automatic servo lock and are precisely controlled isostatic compensation.

4. according to described in claim 2-3 any one unified time frequency reference fiber support network, it is characterised in that The base station that the level Four master slave system optical fiber of described smooth supporting network connects is provided with the micropower transmitter unit of satellite navigation system.

Unified time the most according to claim 1 frequency reference fiber support network, it is characterised in that in described optical fiber Time and frequency standard transmission channel and Optical Supervisory Channel composition honeycomb light banding.

Unified time the most according to claim 5 frequency reference fiber support network, it is characterised in that described subsystem Optical transport network uses wavelength-division multiplex double fine or the transmission of wavelength-division multiplex single fiber.

Unified time the most according to claim 1 frequency reference fiber support network, it is characterised in that frequency of described time Rate standard apparatus is Cs atom clock.

Unified time the most according to claim 1 frequency reference fiber support network, it is characterised in that described subsystem Network also has intelligent optical path control deivce.