Fiber To The Home (FTTH) refers to a fiber that connects directly to the user in a broad sense. FTTH refers to the optical network unit installed at the enterprise user or home user, in the optical access series in addition to the optical fiber to the desktop, it is the closest to the user's optical access network application type.
"FTTH is the dream and technology direction that people have been pursuing for more than 20 years, but due to obstacles in terms of cost, technology, and demand, it has not been promoted on a large scale. However, this situation has recently changed a lot, due to the policy support and the development of technology itself, after many years of silence, FTTH network has once again become a hot spot and entered a period of rapid development. New technologies, new equipment, and new network construction plans have been continuously introduced, which has attracted the attention of the industry. It is expected that ftth networks will develop greatly in the next few years. Therefore, the Code for the Engineering Design of Integrated Cabling Systems (GB 50311-2016) sets out the relevant requirements (mandatory provisions, which require strict implementation and review in the construction of the project).
1. Provisions for fiber-to-subscriber unit communication facilities:
1) In areas where optical fiber transmission has been realized in public telecommunications networks, when setting up user units in buildings, the communication facility engineering must be built in the form of optical fiber to user units.
2) The design of the fiber-to-subscriber unit communication facility project must meet the requirements of equal access of multiple telecommunications business operators, and the communication service users in the user unit can freely choose the telecommunications business operators.
3) When the underground communication pipelines, wiring pipe networks, telecommunications rooms, equipment rooms and other communication facilities of the new optical fiber-to-user unit communication facilities project are built, they must be built simultaneously with the construction project.
4) The user access point should be a logical point specific to the fiber-to-user unit project, and the setting should comply with the following provisions:
(1) Each optical fiber wiring area shall be provided with a user access point;
(2) The user optical cable and the wiring optical cable shall be interconnected at the user access point;
(3) Wiring management can only be carried out at the user access point;
(4) An optical splitter can be set at the user access point.
5) The construction of communication facilities shall be based on the user access point as the interface, and the telecommunications business operator and the building builder shall each undertake the relevant amount of engineering. The implementation of the project shall comply with the following provisions:
(1) The communication pipeline of the building complex and the wiring pipe network in the building within the planning red line shall be the responsibility of the building builder.
(2) The building builder shall be responsible for providing the installation space and the building (equipment room) for the installation of the complex and the communication facilities in the building.
(3) The division of labor in the construction of wiring equipment set by the user access point shall comply with the following provisions:
□ when the telecommunications business operator and the building builder share the wiring box, the construction party shall provide the box and install it, and the wiring module connecting the wiring cable in the box shall be provided and installed by the telecommunications business operator, and the wiring module connecting the user optical cable shall be provided and installed by the building builder;
□ when the telecommunications business operator and the building builder set up the wiring cabinet separately, they shall be responsible for the installation of the cabinet and the optical fiber wiring module in the cabinet.
(4) The wiring cable shall be constructed by the telecommunications business operator, the user optical cable shall be constructed by the building builder, and the optical jumper shall be installed by the telecommunications business operator.
(5) Optical splitters and optical network units shall be provided by telecommunications business operators.
(6) The user unit information distribution box and optical fiber adapter shall be built by the building builder.
(7) The wiring equipment, information sockets and user cables in the user unit area shall be built by the user or the housing builder in the unit.
6) The design of underground communication pipelines shall be carried out in an overall layout with the underground pipelines of the building complex and other facilities in the park, and shall comply with the following regulations:
(1) It should be connected with the upper tube of the light handover box.
(2) It should be connected with the human (hand) hole of the public communication network pipeline.
(3) Maintain a safe distance from power pipes, heat pipes, gas pipes, water supply and drainage pipes.
(4) Avoid areas that are susceptible to strong vibrations.
(5) It should be laid on a good foundation.
(6) The route should radiate outward between the equipment of the building complex, and should be selected under the sidewalk, the green belt next to the sidewalk or the roadway.
(7) The design of underground communication pipelines shall comply with the relevant provisions of the current national standard "Communication Pipeline and Channel Engineering Design Code" GB 50373.
2. User access point settings
1) The number of users under the jurisdiction of each optical fiber distribution area should be 70 to 300 user units.
2) The location of the optical fiber user access point shall be determined according to the wiring area formed by different types of buildings and the density and number of users under its jurisdiction, and shall comply with the following provisions:
When a single building is used as an independent wiring area, the user access point should be located in the integrated wiring system equipment room or communication room of the building, but the telecommunications business operator should have an independent equipment installation space, as shown in Figure 1.
Figure 1 The user access point is located in the device room of a single building
(1) When a large building or super high-rise building is divided into multiple optical fiber wiring areas, the user access point should be evenly set in the floor equipment room in different areas of the building according to the distribution of the user unit, as shown in Figure 2.
Figure 2 User access points are located in shared equipment rooms on the floor area of the building
When the complex formed by multiple buildings forms a wiring area, the user access point should be set up in the building complex property management center computer room, integrated wiring equipment room or communication room, but the telecommunications business operator should have an independent equipment installation space, as shown in Figure 3.
Figure 3 The user access point is located in the computer room or integrated wiring equipment room or communication room of the property management center of the building complex
When each building forms a fiber optic wiring area, and the number of user units is not more than 30 (high configuration) or 70 (low configuration), the user access point should be set in the inlet line room of the building or between the integrated wiring equipment or the communication room, and the user access point should be set up in the way of a common optical cable distribution box, but the telecommunications business operator should have an independent equipment installation space, as shown in Figure 4.
Figure 4 The user access point is located between the inlet lines or the integrated wiring equipment or the communication room
3. User access point configuration principles
1) The capacity of the outdoor communication pipeline pipe hole and the indoor pipe slot required for laying the wiring cable within the red line of the building, the installation space of the wiring equipment reserved at the user access point and the area between the equipment shall meet the needs of the communication service access of no less than 3 telecommunications business operators.
2) The pipes and slot boxes of the outdoor communication pipe and the indoor wiring pipe network required for the optical fiber to the user unit should be set separately, and the total capacity and type of the pipe slot should be determined according to the optical cable laying mode and terminal capacity, and should comply with the following provisions:
(1) The pipe hole of the underground communication pipeline should be selected according to the type and quantity of optical cable laid, and the single hole pipe, the single hole tube and the grid plastic pipe should be selected.
(2) Each optical cable shall occupy a tube hole in a porous tube or a subtube in a single-hole tube separately.
(3) Underground communication pipelines should reserve no less than 3 spare pipe holes.
(4) The size of the pipe and slot box of the wiring pipe network should meet the requirements of the number of wiring cables and user optical cables laid and the utilization rate of the pipe slots.
3) The type of user optical cable and the number of optical fiber cores shall be calculated according to the location, method and number of users under the jurisdiction of the optical cable, and shall comply with the following provisions:
(1) The number of optical fiber cores from the user access point to the user unit information distribution box shall be determined according to the user unit user's needs for communication services and the configuration level, and the configuration shall comply with the provisions of Table 1.
| Table 1 Fiber optic and cable configuration | |||
| disposition | Fiber optic (core) | Fiber optic cable (root) | remark |
| High configuration | 2 | Consider backup of fiber optics versus cables | |
| Low configuration | 1 | Consider fiber optic backups |
(2) 2-core optical cable should be used between the floor optical cable distribution box and the user unit information distribution box.
(3) A single multi-core optical cable should be used between the user access point wiring equipment and the floor optical cable distribution box, and the optical fiber capacity should meet the total capacity needs of the user's optical cable, and the margin of not less than 10% should be reserved according to the specifications of the optical cable.
4) The type and capacity of the optical fiber module on the outside of the user access point should be configured according to the type of wiring cable introduced into the building and the number of fiber cores of the optical cable.
5) The type and capacity of the user-side optical fiber module of the user access point should be configured according to the type of user optical cable and 50% of the number of optical fiber cores of the optical cable or the actual needs of the project.
6) The area between the equipment should not be less than 10 square meters.
7) 1 information wiring box should be set up in each user unit area, and should be installed on the column or load-bearing wall of the building part that is not changed.
4. Selection of cables and wiring equipment for user access points
1) The selection of optical fiber should comply with the following regulations:
(1) The indoor user fiber cable between the user access point and the floor optical fiber distribution box (fiber distribution box) should use G.652 optical fiber.
(2) The indoor user cable between the floor optical cable distribution box (fiber distribution box) and the user unit information distribution box should use G.657 optical fiber.
2) The choice of indoor and outdoor optical cables should comply with the following regulations:
(1) Indoor optical cables should be dry, non-extended flame outer protective structure of optical cables.
(2) The optical cable from outdoor pipeline to indoor should be used for indoor and outdoor optical cables with dry, moisture-proof layer and non-extended flame outer protective layer structure.
3) Optical fiber connectors should adopt SC and LC types.
4) The user access point should use a cabinet or a shared optical cable distribution box, and the configuration should comply with the following regulations:
(1) The cabinet should use a 600mm or 800mm wide 19" standard cabinet.
(2) The common optical cable wiring box shall meet the termination of not less than 144 core optical fibers.
5) The configuration of the user unit information distribution box should comply with the following provisions:
(1) The wiring box should be selected according to the number of information points in the user unit area, the type of incoming cable, the number of cables, and the service function requirements.
(2) The size of the distribution box box should fully meet the needs of various information and communication equipment placement, wiring module installation, optical cable termination and retention, jumper connection, power supply equipment and ground terminal block installation and business application development.
(3) The selection and installation location of the wiring box should meet the needs of indoor users' wireless signal coverage.
(4) When the AC voltage exceeding 50V is connected to the power socket in the box, strong and weak current safety isolation measures should be taken.
(5) The grounding terminal block should be provided in the distribution box, and should be connected to the floor partial equipotential terminal block.
5. Transmission metrics of the user access point
The full attenuation limit of the optical fiber link from the user-side wiring equipment to the user unit information distribution box of the user access point: 0.36dB/km when using G.652 optical fiber in the 1310nm wavelength window, 0.38~0.4dB/km when using G.657 optical fiber, 0.06dB/pcs for optical fiber joints using hot welding method, and 0.1dB/pcs for cold connection.
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