FTTH access technology---PON

1) passive optical network (PON) FTTH applications in the problems facing our country

Ideal passive optical network (PassiveOpticalNetwork - PON) The main features are: Optical Line Terminal (OpticalLineTerminal - OLT) placed in the center room carriers, passive optical splitter placement (Splitter) as close to the client's optical network unit ( OpticalNetworkUnit - ONU). The distance between the OLT and ONU is equal to the center room carriers to the user's distance, with the current fixed-line access from the similar, typically a few kilometers, Splitter typically tens of meters away from the ONU to a few hundred meters. PON structure and layout of this highlights the advantages of PON: from the center room to the user's entire network of passive network; substantial savings to the user's central office cable resources; because it is a multipoint to streamline the engine room and the number of devices scale, reducing the number of engine room wiring.

Passive optical network (PON) in the residential area ideal layout: OLT put telecom operators engine room, as close to the user according to the principles Splitter, Splitter placed on the floor wiring box. Obviously, the ideal layout to highlight the inherent advantages of PON, but will inevitably bring about the following questions: First, from the center room to the core area requires a high number of fiber optic cable, such as the 3000 area, according to the calculated branching ratio 1:16, needs nearly 200 core cable, and now generally only 4-12 core, to increase the laying of fiber optic cable is very difficult; second, the user can freely choose operators, telecom operators can only choose a single service provided, the inevitable emergence of a single operator monopoly business situation is not conducive to multi-carrier competition can not be effective in protecting the interests of users; third, passive optical splitter box will be placed floor wiring wiring nodes are scattered, leading to telephone numbers, maintenance and management is very difficult, or even impossible; fourth, can not improve network access port equipment and its utilization, because the coverage in a single PON, the user access rate is difficult to be 100%.

Passive optical network (PON) in the residential district of reality layout: OLT and Splitter are placed in the community room inside. Advantage of this layout is the reality: the center room to the core residential area only a few low-fiber, existing resources can meet the needs of fiber optic cable; the entire residential area access lines are in the community room wiring, allowing users to choose different carriers, operators of telecommunications networks is very easy to distribute telephone numbers, maintenance and management; the same as access devices and patch panels in the community room, no doubt significantly improve device port utilization, access devices can access expansion and gradually increase the number of users . However, the layout of this reality has its obvious shortcomings: First, discard the PON network structure is the biggest advantage of the passive network, the center room to the user network, or active network; Secondly, there is no savings because PON and fiber resources; addition , PON equipment costs are high, the network structure complex.

In summary, PON FTTH applications in the residential area on both sides of the contradictions that exist: the ideal according to the PON network architecture and layout of the course can play its original advantages: from the center room to the user's entire network of passive network, a lot of room to save center to the user's cable resources, streamline the number and size of engine room equipment; but it also brings almost impossible to accept the disadvantages: need a substantial increase in the laying of fiber-optic cables; wiring nodes scattered, Telephone Number, maintenance and management extremely difficult; users can not freely choose operators, is not conducive to multi-operator competition, the interests of users can not be effectively protected; network equipment and access port utilization rate. If the use of passive optical network (PON) in the reality of the layout of residential areas, existing resources can meet the needs of fiber optic cable, wiring residential room unified, easy to distribute telephone numbers, maintenance and management, the user can freely choose operators, significantly increased device port utilization, but also discarded the PON is a passive optical network resources and conservation of these two advantages, the present must also endure the high cost of PON equipment, network complexity and other disadvantages.