The Definition & Application of FTTH Technology

Whats FTTH

FTTH (Fiber To The Home), as the name suggests, is the optical fiber directly access to the home. To be precise, FTTH refers to the installation of optical network units (ONU) in home users or business users. Fiber to the home is the closest type of optical access network application to the user in the optical access family, except FTTD (fiber to the desktop).


fiber to the home not only gives users greater bandwidth, but also enhances network transparency of data formats, wavelengths, rates, and protocols, relaxes the demands for environmental conditions and power supply, and makes it very convenient for maintenance and installation.


fiber to the home


Fiber To The Home belongs to the access network part. The access network is the part between the central office or the remote module and the user, which mainly completes the multiplexing and transmission functions, and generally does not include the switching function. Historically, this part was also known as the local loop or subscriber loop. According to the definition of ITU-T, Fiber To The Home means that the optical fiber reaches the door of the household, and there is no copper wire between the end office and the household. The FCC in the United States defines a new meaning for “H” in FTTH. “H” includes both narrow sense Households, but also small business establishments. Combining the above two definitions, the definition of FTTH: FTTH uses optical fiber as the transmission medium to provide end users such as families and small business organizations with access to telecommunications end offices, and has information multiplexing/multiplexing functions.


There have been many FTTx in history, including FTTP (fiber to the premises), FTTB (fiber to the building), FTTC (fiber to the curb), FTTN (fiber to the neighborhood), FTTF (fiber to the floor), FTTZ (fiber to the community), FTTO (fiber to the office), etc. The defined FTTH includes FTTP, FTTF, FTTO, and FTTN, and other FTTx are not included.


Typical Fiber To The Home Networking

FTTH adopts a point-to-multipoint (P2MP) single-fiber bidirectional optical access network with a tree or star topology, consisting of OLT on the network side, ODN on the optical distribution network and ONU (ONT) on the user side. Among them, OLT (optical cable terminal equipment) is an important central office equipment, which is connected to one or more ODNs to provide a WAN interface upwards, and is generally connected to a tandem switch or directly connected to a BRAS. Provide 2.5G optical interface to ODN downward, with the functions of centralized bandwidth allocation, control of optical distribution network, real-time monitoring, operation, maintenance and management of passive optical network system.


FTTH Optical Cable Construction

Construction Principles

EPON-based FTTH residential buildings and optical distribution network ODN construction in residential quarters should comprehensively consider the type of building, environmental conditions and short-term and long-term user needs. Optical distribution network structure in tree or star topology. In principle, villa-type residential areas adopt the first-level light-splitting method, and other types of residential buildings and residential areas adopt the second-level light-splitting method. It is recommended to use 1:64 splitting system. The optical channel attenuation value of the optical distribution network shall comply with the “Interim Provisions on EPON Network Optical Interface Test Indicators (Trial)”. In order to save engineering investment, the PON port of the optical splitter and OLT is gradually configured in place in 2 to 3 times according to the needs of user development (thin coverage), but the capacity of the optical cable is configured in place at one time according to the final demand. In the specific construction process, it is necessary to target Different types of buildings to adopt different construction schemes. For example, the FTTH access method can be used preferentially for newly-built communities. If the developer has built a Category 5 line for households, the Chirp access method can be used; Residential quarters on the line can be transformed by FTTB.


Key points and difficulties in construction

The ODN network is the focus and difficulty of Fiber To The Home construction. The optical access network is the foundation of urban informatization development, which will directly affect the informatization development level of the region in the next 20 years or even longer, and the ODN network is the focus and difficulty of FTTH construction. There are many problems related to ODN network construction and operation and maintenance, but from a technical point of view, they are mainly the following aspects:

(1) unified construction standards and product standards;

(2) the problem of optical cable households in old areas;

(3)Home wiring and terminal selection:

(4) ODN network fault location and automatic activation system;

(5) comprehensive resource management.


According to the actual situation of the system, the optical fiber cable of the Fiber To The Home user’s lead-in section needs to select the appropriate optical fiber and optical cable structure by comprehensively considering the type, parameters and scope of application of the optical fiber. In addition to laying the optical cable into the household through pipelines and direct burial, the general FTTH residential section optical cable should use a butterfly drop cable, and its performance should meet the requirements of YD/T 1997-2009 “Butterfly Drop Cable for Access Network”. In the indoor environment, it is recommended to use a butterfly-shaped lead-in cable with a white sheath to improve user satisfaction with the construction: In an outdoor environment. For optical cables laid overhead, along the outer walls of buildings, or by nailing outdoors, it is recommended to use self-supporting butterfly-shaped lead-in optical cables with black sheaths to meet the requirements for UV resistance and increase the mechanical strength of optical cables.


The organization of construction personnel is to effectively organize personnel and equipment according to the construction operation plan to ensure construction safety, control construction quality and progress, and reduce construction costs.


Compared with copper lead-in cables, butterfly-shaped lead-in cables are light in weight and can bring convenience to construction, but due to the small diameter and poor toughness of the optical fibers, higher requirements are placed on construction tools, instruments and construction techniques, which increases the Construction difficulty. Therefore, the construction and management personnel of Fiber To The Home users’ introduction section of optical cable need to inject new line construction and management concepts, master advanced optical cable line construction and maintenance technology and advanced management methods, and reorganize and arrange construction work teams. In order to ensure the safety of laying Fiber To The Home household optical cables and improve construction efficiency, generally each construction team should consist of at least 2 people. And everyone should master the basic technical essentials and construction operation methods of household optical cable installation and maintenance.


In order to improve the construction quality, ensure the personal safety of construction personnel, shorten the construction operation time, and reduce the maintenance workload in the construction of household optical cables, it is recommended that the common construction tools equipped by each construction team include ladders, inclined 13 pliers, needle-nose pliers, screwdrivers, Electrician’s knife, utility knife, safety belt, impact drill, hole opener, pipe Pierce, flashlight, silicone gun, Miller pliers, movable linker, alcohol bottle, red light pen, hand-held light source and optical power meter, etc.



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