What is light advancing and copper retreating?

Optical advancement and copper exit is a project proposed by China's fixed network operators China Telecom and China Netcom to gradually realize fiber optic access (FTTx) and replace copper cables with optical fiber. China's fixed network operators are now The ADSL access network used is generally central office centralized mode, that is, the ADSL MODEM at the user's home needs to synchronize signals with the ADSL central office equipment in the telecommunications branch. This distance is generally more than 3 kilometers. In this way, distance has become the biggest problem in speeding up domestic ADSL technology. Therefore, the strategy of "advancing optical fiber and withdrawing copper" is to combine FTTx technology with ADSL technology to shorten the distance between the ADSL central office equipment (DSLAM) and the copper line at the user's home as much as possible to provide high-bandwidth access.

FTTx construction model

FTTC (Fibretothecurb) + xDSL mode: fiber to the roadside, moving broadband access equipment down to the "roadside" or "community computer room", that is, Move from the "trunk section" to the "feeder section" to ensure that the distance from DSLAM to the user terminal is less than 2 kilometers. ADSL, ADSL2+, and VDSL technologies can be used in this section.

FTTB (FibretotheBuilding)+xDSL mode: fiber to the building, move the broadband access equipment down to the "location of the junction box of the building", that is, from the "feeder section" to the "subline section", Ensure that the distance from DSLAM to the user terminal is less than 1 km. ADSL, ADSL2+, and VDSL technologies can be used in this section.

FTTB (Fibre to the Building) + LAN mode: The distance between the broadband access equipment and the user terminal is required to be less than 100m (Ethernet technology limitation), and it can provide 10M/100M/1000M two-way symmetrical bandwidth. ·FTTH (Fibre to the Home) mode: Fiber to the home (office) can provide users with bandwidth from tens of megabits to gigabit. This mode is a once-and-for-all solution to some problems in the access network, but there are still There are many problems such as access equipment, home optical fiber cabling, and cost.

When constructing and transforming access networks, operators will comprehensively consider CAPEX, OPEX, ROI, the bandwidth requirements of new services, and the optimal utilization of existing copper cable resources, and flexibly choose the FTTx construction model to obtain the best results. Excellent input-output ratio. Capital expenditure (CapitalExpenditure, CAPEX) is calculated as: CAPEX = strategic investment + rolling investment, which refers to capital expenditures used for infrastructure construction, expanded reproduction, etc. that need to be amortized in multiple fiscal years; operating expenses (Operating Expense, OPEX) refers to the operator's cost of operating the network; return on investment (ROI) refers to the amount of profit or cost savings achieved by a specific use of funds