Why Is the FTTH Cabling System Divided Into Multiple Cable Segments

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Fiber-to-the-home (FTTH) fiber optic
cabling is generally divided into the trunk part, distribution part, the
introduction part, and access part from the base station to the user.

 

In general, the fiber cable link system
will be more secure if the fewer fiber cable segments make out from a fiber
cable link. So why is the FTTH
cable route divided into so many cable segments?

 

01

If the fiber link from the base station
to the user passes through only one fiber cable segment (not counting the jump
optical fiber), that is, each user has a direct cable to the board, What is the
problem?

 

There are two main problems here. (1)
The number of fiber optic cables connected to the base station is large, and
the number of incoming fiber optic cables that can be tolerated by one base
station is limited; (2) The distance for laying the fiber optical cable during
installation is long, which is not convenient for installation. Limited by the
above two aspects, such a base station can only allow dozens of users to
access, and of course, there is no application set.

 

02

In order to solve the above problems,
we made 2 improvements.

 

(1) The fiber optical cable is out of
the way with a large-core fiber optical cable, and then the fiber cable splice
closure is divided into a plurality of small-core optical cables. It should be
noted that if a fiber optic cable has too many branch points, it will affect
the life and transmission indicators of the cable.

 

(2) Set the fiber distribution box at
the location where the user is concentrated, as the branch point between the
project and the loading. When the user puts the device, it is only necessary to
put a small cable from the fiber distribution box to the user.

 

It is estimated that there are 10 fiber
optical cables in one office, 6 to 12 fiber distribution boxes in each optical
cable, and 8 users in each fiber distribution box. The number of service users
in one office is 480 to 960. At this point, the fiber optic cable line from the
office to the user has become two cable segments: Base station – distribution
box, distribution box- user. Since the connection relationship of the optical
fiber is fixed at the optical cable splice closure, and the attenuation is
small, the cable splice closure is generally not used as the starting point of
the segment.

 

Compared with Figure 1, the number of
service users in the office has increased several times, but the capacity is
still too small. In addition, the user’s development is dynamic. If a location
needs to add a fiber distribution box, it needs to be re-laying fiber cables
from the base station.

 

03

As can be seen from the comparison of
reducing the number of outgoing optical cables and facilitating the loading,
the capacity of the lifting station can be realized by adding branch points on
the optical cable. There are two types of fiber optic cable branch points:
fiber cable distribution box and fiber optical splice closure.

 

Through the optical cable distribution,
one optical cable can be divided into multiple optical cables, and the number
of different branches can be mainly limited by the laying conditions of the
optical cable; the connection relationship between the optical cables is
flexible. But it will increase the loss of active connections and make core
management more difficult.

 

The number of cables that can be
branched through the fiber spice closure is small, generally no more than 6 (1
into 5). There are generally cables left on both sides of the fiber splice box.
If there are more cables in a splice closure box, the cable will appear messy
and unsightly. Therefore, in general, the number of fiber splice closure to
divergent fiber cables will be controlled within 4 (1 into 3).

 

By adding a fiber cable distribution
box , the number of service users in a distribution box is 480 to 960, and the
number of service users in one transfer box is 8 to 12, and 6 to 12 fiber
feeders are placed in each of the fiber-optic cables.

 

So how many fiber cable branches can a
base station set? With 10 optical cables out of one base station and 3 optical
connections per optical cable, 30 optical connections can be set. In this way,
the capacity of a base station is about 14400-28800; such a large capacity can
basically meet the needs of a large number of field.

 

The construction of the project will be
limited by the construction conditions. For example, if the fiber optical cable
network is to cover a residential area, the optical communication is preferably
set in the residential area. However, when constructing a backbone optical
cable base station, most of the residential properties will not be allowed to
be constructed in their communities. When the market department and a certain
community negotiated the conditions for engineering construction, the backbone
optical cable project has already been completed.

 

The demand for engineering construction
in residential areas, commercial buildings, and other cluster markets in the
city are uncertain, and the construction of trunk optical cables must be
completed within a certain period of time (generally within 2 to 3 months). In
order to solve this contradiction, in the construction of the backbone optical
cable, the trunk ONU is placed in a location close to the potential user group,
convenient for the cable to be laid, and the installation conditions.

 

When there are construction conditions
in residential quarters, commercial buildings, and other cluster markets,
installing distribution ONU and wiring fiber cables from trunk ONU to
distribution ONU as shown in Figure 6. Thus, the optical cable line from the
base station to the user is divided into the following: the trunk section, the
wiring section, the lead-in section, and the home section.