Comparison of FTTX access based on PON

At present, the high-bandwidth access networking mode is mainly PON-based FTTX access. The main aspects and assumptions involved in cost analysis are as follows:

Device cost of the access segment (including various access devices and lines, and average to each first-line user)

Construction cost (including construction cost and other overhead cost, Usually 30% of the total device price)

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

Regardless of the actual installation rate (that is, the actual installation rate is 100%)

The required device costs are calculated based on 500 user models.

Note 1: the cost of the Residential data center is not taken into account for FTTX access;

NOTE 2: When the ADSL2 + ACCESS distance is 3km, it has no advantage over ADSL. Currently, VDSL2 is not used much and is not compared for the time being;

NOTE 3: optical fiber access has obvious advantages over long distances.

FTTB + LAN

The local terminal is distributed to the aggregation switch of the residential area or building through optical fiber (3 km), connected to the corridor switch through optical fiber (0.95 km), and then distributed to the user end using the five-class line (0.05 km. The calculation is based on the 500 user model (without considering the cost of the Residential data center). At least one 24-port aggregation switch and 21 24-port corridor switches are required. In actual use, an additional level-1 switch is generally added. Although the total number of switches increases, corridor switches use lower-price models, which reduces the total cost.

FTTH

Consider placing an OLT on the local terminal, a single optical fiber (4 km) to the center data center of the residential area, and passing the Optical Splitter (0.8 km) to the corridor in the center data center of the residential area, the corridor goes through Optical Splitter (0.2 km) to the user end. Calculated based on the 500 user model (without considering the cost of the Residential data center): the cost of the OLT device is allocated based on the scale of 500 users, and a total of 16 OLT ports are required.

FTTC + EPON + LAN

We also consider placing an OLT on the local terminal, a single optical fiber (4 km) to the center data center of the residential area, and a Optical Splitter (0.8 km) to the building in the center data center of the residential area, each corridor uses a Optical Splitter (0.2 km) to access each floor, and then uses five types of lines to access the user end. Each ONU has a layer-2 switching function. Considering that ONU has 16 FE ports, that is, each ONU can access 16 users, which are calculated based on a model of 500 users.

FTTC + EPON + ADSL/ADSL2 +

For applications with the same DSLAM move down, consider placing an OLT on the local terminal. A single optical fiber (5 km) is transferred from the BAS terminal to the general terminal, and the average terminal is allocated by Optical Splitter (4 km) to The ONU in the center data center of the residential area, ONU is directly connected to DSLAM through the FE interface, and then connected to the user end using a twisted pair wire (1 km) copper cable. It is also calculated based on 500 user models under each DSLAM (the cost of the Residential data center is not taken into account ).

Point-to-Point Optical Ethernet

The local terminal is distributed to the aggregation switch of the residential area or building through optical fiber (4 km), and then directly distributed to the client through optical fiber (1 km. Based on the model of 500 users (without considering the cost of the Residential data center), at least 21 24-port aggregation switches are required, and 21-to-4-kilometer trunk optical fiber cables are laid from the local data center to the residential Data Center Aggregation switch. Currently, point-to-point Optical Ethernet is not widely used for broadband access in residential areas. It is generally used for the networking of scattered important users. Therefore, its construction department is different from other access methods, therefore, the calculation method is different.

Simple comparison of various networking Modes

The guaranteed bandwidth, maximum accessible bandwidth, and unit bandwidth investment costs of various technologies in various networking modes are shown in the table.

From the above analysis, we can see that different optical splitter placement locations have a direct impact on the usage of optical fiber, which also affects the cost of network construction; at present, the cost of EPON equipment is mainly limited by the burst light sending/receiving module and the core control module/chip, the price of E-PON module is constantly lowered to meet the needs of the market; Compared With xDSL, PON has a high one-time investment cost and is currently mainly used in intensive user areas that are newly created or reconstructed. Point-to-Point Optical Ethernet, due to the high cost is only suitable for scattered government and enterprise customers, and the adoption of FTTC + E-PON + LAN or FTTC + EPON + DSL is a better solution for gradual transition to FTTH.

1. PON system networking in FTTX scenarios
2. FTTX + DSL drives broadband access upgrade to a rapid development stage