Comparison of five PON-based FTTX access

The current high-bandwidth access networking method is mainly based on PON-based FTTX access. The main aspects and assumptions involved in the cost analysis are as follows:

●Equipment cost of the access section (including various access equipment and lines, etc., averaged to each line user)

●Engineering construction costs (including construction fees and other overhead costs, generally 30% of the total equipment price)

●Operation and maintenance costs (usually about 8% of the total cost per year)

●The installation rate is not considered (that is, the installation rate is 100%)

●The required equipment cost is calculated based on 500 user models

Note 1: FTTX access does not consider the cost of the community computer room;

Note 2: ADSL2+ has no advantage compared with ADSL when the access distance is 3km. VDSL2 is currently not widely used, so no comparison will be made for the time being;

Note 3: Optical fiber access has obvious advantages at long distances.

FTTB+LAN

The central office is routed through optical fiber (3km) to the aggregation switch of the residential area or building, and then connected to the corridor switch through optical fiber (0.95km), and then routed to the user end using Category 5 cable (0.05km). Calculated according to the 500 user model (without considering the cost of the cell room), at least one 24-port aggregation switch and 21 24-port corridor switches are required. In actual use, an additional level of switch is generally added. Although the total number of switches increases, the use of lower-priced models of corridor switches reduces the total cost.

FTTH

Consider placing an OLT at the central office, a single optical fiber (4km) to the cell central computer room, in the cell central computer room through a 1:4 optical splitter (0.8km) to the corridor, and a 1:8 optical splitter (0.2km) in the corridor user terminal. Calculated according to the 500-user model (without considering the cost of the cell room): The cost of OLT equipment is allocated on the scale of 500 users, requiring a total of 16 OLT ports.

FTTC+EPON+LAN

Also consider placing the OLT at the central office. A single optical fiber (4km) will be sent to the central computer room of the community. The central computer room of the community will pass through a 1:4 optical splitter (0.8km) to the building. In each corridor, a 1:8 optical splitter (0.2km) will be used. ) Go to each floor, and then connect to the user terminal with Category 5 lines. Each ONU has a Layer 2 switching function. Considering that the ONU is equipped with 16 FE ports, that is, each ONU can access 16 users, which is calculated according to the 500 user model.

FTTC+EPON+ADSL/ADSL2+

For the same application of DSLAM downward shift, consider placing an OLT at the central office, and a single fiber (5km) from the BAS end office to the general end office, and at the general end office, passes through a 1:8 optical splitter (4km) to the ONU in the cell center computer room. The ONU is directly connected to the DSLAM through the FE interface, and then connected to the user end with a twisted pair (1km) copper cable. It is also calculated based on the 500 user model connected to each DSLAM (without considering the cost of the cell room).

Point-to-point optical Ethernet

The central office is deployed through optical fiber (4km) to the aggregation switch of the community or building, and then directly deployed to the user end through optical fiber (1km). Calculated according to the 500 user model (without considering the cost of the cell room), at least 21 24-port aggregation switches are required, and 21 pairs of 4 kilometers of backbone optical fibers are laid from the central office computer room to the aggregation switches in the cell. Since point-to-point optical Ethernet is not generally used for broadband access in residential areas, it is generally only used for the networking of scattered important users. Therefore, its construction department is different from other access methods, so the calculation methods are also different.

From the above analysis, it can be seen that the placement of the optical splitter will have a direct impact on the fiber usage, which also affects the cost of network construction; the current EPON equipment cost is mainly limited by the burst optical transmit/receive module and the core control module/ Chips and E-PON module prices are constantly being lowered to meet market needs;  compared to xDSL, the one-time input cost of PON is higher, and it is currently mainly used in newly built or rebuilt dense user areas. Point-to-point optical Ethernet is only suitable for scattered government and enterprise customers due to its high cost. Using FTTC+E-PON+LAN or FTTC+EPON+DSL is a better solution to gradually transition to FTTH.