1. Definition of Broadband Optical Access Network
 

Broadband optical fiber access refers to an access-bearing mode in which optical fiber is used as transmission medium between user network interface and related service node interface, or optical fiber is used as backbone transmission medium, and metal wire or wireless is used as user terminal transmission medium.

FTTx Application Types

Typical Application types of FTTx networks include FTTH, FTTO, FTTB, FTTCab, etc.

FTTH: Fiber To The Home. It refers to a fiber optic cable running directly from the Internet Service Provider (ISP) to a home or business location.

FTTO: Fiber To the Office. It is an access method that uses optical fiber to connect the communication office and company or office users.

FTTB: Fiber to the Building. It is a type of fiber-optic cable installation where the fiber cable goes to a point on a shared property and the other cabling provides the connection to single homes, offices or other spaces.

FTTCab: Fiber To The Cabinet. It is a network architecture where optical fiber replaces copper in the access network connection between the local exchange and street cabinets.

2. Definition of PON

Passive Optical Network (PON) is composed of Optical Line Terminal (OLT), Optical Splitter and Optical Network Unit (ONU) with tree topology. “Passive” means that the ODN (Optical Distribution Network) between OLT and ONU has no active electronic device.

3. Single-Fiber Bidirectional Transmission of PON

PON uses Wavelength Division Multiplexing (WDM) technology to simultaneously process bidirectional signal transmission. The uplink and downlink signals are transmitted in different wavelengths but in the same optical fiber. The direction from OLT to ONU/ONT is downward, and vice versa.

4. PON Network Construction Mode

FTTB (PON) + LAN refers to the use of PON technology to achieve fiber-to-building deployment in the building to support multi-user ONU, using twisted-pair cable to access ONU to the end user, providing data and voice services for multiple users.

FTTH (PON) refers to the use of PON technology to achieve fiber to the home, and each home user deploys an ONU to provide data and voice services for a single home user.

5. OLT

OLT Deployment Principles

1) Terminal office or sub-office is preferred for OLT deployment.
2) In the case of a large residential coverage area and a dense number of users, the computer room in the residential area can be selected as the secondary placement point for OLT equipment.
3) The coverage of EPON OLT should be within 5km, and should not exceed 10km. Rural areas should also be limited to 15km, preferably within 10km.
4) The GPON OLT coverage should be within 10km and should not exceed 20km.
5) The OLT to SR/aggregation switch link is GE or multi-GE at the initial stage and should be extended to 10GE in the middle and later stages.

PON Port Planning
1) Algorithm for the number of users covered by a single PON port: service bandwidth demand < access capacity provided by the PON port
2) PON ports is distributed in units of user sub-regions, and each user sub-region determines the number of PON ports required for planning according to the user attributes and the number of final users.
3) PON ports are not allowed to cross multiple user sub-regions. PON ports should be distributed based on customer groups, such as FTTH, FTTN, FTTO, etc.

6. ONU Deployment Principles

PON+LAN

1) Generally choose fixed ONU, the height of the equipment should not exceed 2U.
2) The distance between ONU and users should not exceed 100m, and adopt category 5 cable for households.
3) ONU is generally placed in communication shaft, distribution box or junction box in the building, which should be selected according to the actual situation.
4) ONU mainly uses local power supply, using AC 220V power supply.

PON+DSL
1) Generally use Plug-in ONU
2) The coverage distance of copper cable (twisted pair) from users is generally within 500m
3) ONU is usually placed in or beside the building

FTTH
1) ONU equipment should use 2 ports or RJ45 with 2-4 ports
2)  ONU should be installed in the user's home, rather than at the door or corridor
3) The user's indoor ONU should be installed in an embedded device box instead of placed on the desktop to avoid pigtail damage. For users with uncertain needs, install a light panel and provide ONU when users need broadband service
4) Its supply power is AC

7. ODN - Optical Splitter

Splitter Deployment Principles

1) Splitter deployment should follow the principle of centralized placement. In rural areas and other areas with few users, use planar optical waveguide (PLC) splitters
2) EPON splitting ratio should be 1:16, the maximum can not exceed 1:32; GPON splitting ratio should be 1:32
3) In engineering configuration, each splitter should be reserved for 1 downlink port for daily testing
4) The optical splitter should be placed in the optical splitter box and the computer room of the residential area