【 Weak current College 】 optical transmission network planning cable cores and fiber type determines the influence factor

1 background to

In recent years, China's telecom networks takes on a growing trend in the telecom business continued rapid growth in the size of the telecommunications network has the highest in the world, as the basis for telecommunications networks optical transmission network of development by leaps and bounds.

Optical transmission network is the foundation of telecommunication networks, its plan, is the construction of telecommunications networks. Currently, the construction of optical transport network, transmission equipment and optical fiber cable line are the two basic elements, where yu low twin chant waste plan around your car tomb packing fragile Sun Yu Jie twin chant humming waste milk low-car different ǖ description where hop R Wong-gun yu twin chant waste low withdrawal na 晗 Huo Ji Hun milling I say 5 to 20 years; the second is the laying of optical fiber cable line systems is difficult to transport equipment to upgrade or update to accommodate network demands, while the optical fiber cable line systems once finished laying is very difficult to make large-scale changes; the third is the optical fiber cable line systems one-time investment in occupies a comprehensive construction costs higher weighting. Therefore, in the optical transport network planning and construction, must be carefully planning must take account of optical fiber cable line in future l5-20 years life is still unmet transport capacity and rate of development of the need to build a reasonable structure, flexible security, can fully meet the needs of the future development of the optical cable network.

2 related factors

Optical transmission network planning in optical fiber core number and type of a more complex forecasting process, to transport demand forecasting and transfer points carried out for the Foundation. Due to fiber optic cable service life is long, but all these factors limit the effect on forecast accuracy and operational impact (especially for medium-and long-term), therefore, the need to take into account the effect of the optical transmission network planning in optical fiber core number and type of factors through lists and analysis.

2.1 transmission network level

Basic telecommunication transmission network in China is divided into three levels, namely the national trunk (interprovincial) transmission network, provincial secondary main line transmission network and local transport network. Corresponding optical fiber cable line is divided into three levels, namely the level Cabel, L2 trunk cable and fiber-optic local network. Local transport network can be divided into local backbone transmission network and the local transmission network access layer. Level link, L2 trunk, local backbone transmission system of distances, the rate is high, at present the system basically have application Division; local access layer transmission network transmission distances are relatively short and systematic rate is not high, the current application Division. Therefore, depending on the level of basic transport networks to determine the selection of optical fiber types.

2.2 fibre types

Single mode fiber with its decay, frequency bandwidth, large capacity, low cost and ease of expansion, etc., as an ideal communication transmission medium in the world are very widely used. At present, with the advent of the information society, people of the optical fiber amplifier, TDM, WDM and frequency division multiplexing technology, which makes single-mode fiber transmission distance, communications capacity and the transmission. To further improve the transmission rate.

ITU-T in accordance with zero dispersion wavelength and as wavelength shift or not will be single-mode fiber consists of G.653 G.652,, G.654, G.655,: G.652 G.655 fibers in the present, in common use. All types of optical properties and application characteristics are as follows:

(1) G.652 fibre (non-dispersion-shifted single mode fiber)

Conventional single-mode fiber 1310nm wavelength performance is the best single-mode fiber, currently the most widely used, mainly used in 1310nm wavelength area open long distance 622Mbit/s and the following system, 1550nm wavelength region opened 2.5Gbit/s or N×2.5Gbit/s WDM system.

Low water Peak Singlemode Fiber (full-wave fiber), the advantage of working wavelength range, reached 1280-1625nm, mainly used in DWDM transport system of the metropolitan area, provides the l20, or more of the available channels.

(2) G.653 fibre (dispersion shifted SM Fiber)

1550nm wavelength performance best single mode fiber, is by the zero dispersion wavelength 1310nm moved to minimum attenuation of 1550nm wavelength area of single-mode fiber. 1550nm wavelength area it not only has the minimum attenuation characteristics, and is zero dispersion wavelength, and therefore this fibre is mainly used for long-distance l550nm wavelength region opened l0Gbit/s and above in the system. But since the working wavelength zero dispersion area of nonlinear effects, can have serious four-wave mixing, does not support WDM systems, it is used only for single channel high-speed system, such as single-channel thousands of kilometers of submarine system and long distance land lines. Due to new or reconstructed terrestrial high capacity fiber optic transmission systems for WDM systems, the application of G.653 fibre is very small.

(3) G.654 fibre (as of wavelength shift single mode fiber)

1550nm wavelength attenuation lowest single-mode fiber, and producing special difficulties, the price is very expensive, so it is rarely used. Mainly used in long distance without insert active devices of no relay submarine fiber-optic communication systems, terrestrial transmission is generally not used.

(4) G.655 fibers (non-zero dispersion-shifted SM Fiber)

It also overcomes G.652 fibre in 1550nm wavelength dispersion of G.653 with large and 1550nm wavelength optical fiber in the nonlinear effect does not support WDM system faults. 1550nm wavelength region is mainly used for the opening of 10Gbit/s and above in WDM high-speed transmission system.

Fiber type selection end and transmission system for transmission distance, system and application Division.

2.3 life

Currently, fibre use lifetime is typically 15-20 years.

2.4 transport network programme

Transmission network in accordance with theAs far as the optical fiber cable line of specific physical routing, and on this basis, the transport node distribution, distance, set, ratings, rate, network security, etc. Different transport networks programme will directly influence the choice of cable cores. For example, network security, SDH self-healing ring protection method can take two fiber unidirectional path switching ring, second fiber bi-directional multiplex switching ring and four fiber bi-directional multiplex switching ring; two intersecting coincident partial SDH ring may use shared fibre virtual protection ring or stand-alone fibre protection ring, etc.

In addition, taking into account the different levels are the same as the long distance transmission network cable routing lots of cable construction to avoid duplicate investment, may use in the construction of Cabel local networks fiber needs into account, when you use the local network in the future may be in the nearest Cabel connectors open for fiber. So, the Cabel's core number will increase.

2.5 transmission business service object

Different transport business service object will also affect the optical transmission network planning and determination of the optical fiber core number to cellular mobile telecommunication network, for example, its transmission business service object has a macro cellular base stations, micro-cellular base stations, fiber optic Repeater, data access point, and so on. Because the service object, its transmission network access modes will also be different. Such as micro-cellular base stations is generally not equipped with batteries, in order to ensure the safe operation of the transmission network is not affected by the outage, generally not the micro-cellular base station transmit into SDH ring, which is a separate 2 core fiber opened chain type system; fiber-optic Repeater is a direct-attached, the need for separate occupation 2 core fiber-to-end base station. According to the above-mentioned transfer service objects for different classes, you can identify each piece of fiber optic cable cores. In addition the determination of optical fiber core number should also take into account the number of rental, alternate fibre optic fiber number, etc.

2.6 laying

Fiber optic cable laying main pipe laying, buried, cableway. Different laying on future expansion and construction of optical cable line speed and flexibility from low to high impact sequence: buried, aerial laying, pipe laying. Optical fiber cable line expansion of high speed and flexibility, then on cable cores of forecasting can be relatively conservative, but should consider pipeline resource expensive and limited.

2.7 economic development

Local economic development level and speed will directly affect the optical transmission network planning cable cores and determination of fiber types. From China's national conditions and future development needs, our country in Eastern area of the construction of the new route will gradually shift to l0Gbit/s and above-based WDM system, in this case, the cost of fiber-optic system G.655 will than using the traditional G.652 fibre system costs. At the same time, our country has a highly uneven economic development, China's Western region of the communications business needs in a very long time to catch up with the eastern region, thus adopted 2.5Gbit/s-based WDM systems, would be sufficient to meet the long route of business needs. At this rate, the use of G.655 fibers of necessity and urgency are not so strong. Similarly developed areas of communication demand that their local cable cores need more Western region.

2.8 future new technology development and application of

Communication technology is advancing rapidly, in the near future, as all-optical networks, optical transport networks, new technologies such as optical Internet access and applications, optical transmission network pattern changes, but all-optical networks, optical transport networks, optical Internet and other new technologies in transport physical media is still a fiber, optical transmission network planning cable cores, type determines is necessary to take into account the application of new technologies in the future and development.

2.9 economics

Optical fiber cable line systems one-time investment in occupies a comprehensive construction costs higher weighting. In optical fiber core number, type of, you must consider the economics of the construction project. On the one hand, blind pursuit of fiber optic cable system apparatus configuration or G.655 fibers will enable optical fiber cable line systems construction investment is too large, too much wasted idle fiber resources. On the other hand on the future development of estimates, just consider the present network requirements and conserving construction investment, fibre resources do not meet the business needs, the optical fiber cable line systems of the construction cost of the expansion will more than tenfold, dozens of times. With economic development, improvement of urban planning system, optical fiber cable line systems (using an existing pipeline construction) construction costs will be higher and higher.

3 Summary

Through the above discussion, one can see the optical transmission network planning in optical fiber core number and type of a more complex decision-making process, predict and forecast accuracy, reasonability, forward-looking, and economics to promote local economic development, improve communications, the competitiveness of enterprises and reducing operational costs have a significant impact.