# Design and Implementation of a Passive Optical Network for a Small Town +
## 4 Results  
When designing splitters in a PON network, the basic rule for the GPON is that the product of the first-level and second-level splitting coefficients should be equal to 64, with first-level splitters installed in existing street cabinets or in a technological building when the area around it is directly served. The design of the branching ratio in the splitters is carried out in the direction from the building entrances to the aggregation point in the following sequence (Figure 1):  
* Based on the number of households, the branching scheme is first determined. * All second-level splitters with a division ratio of 1:8 are connected to the outputs of first-level 1:8 splitters located in inspection shafts or a technological room. * The number of first-level splitters determines the number of fibers that will be needed in the connecting cable to the technological room where the OLT is located. * First-level splitters are placed in an existing street cabinet or in the technological building itself, when it is serviced immediately around it. * The number of first-level splitters determines the number of OLT SFPs that will be needed in the local central office. * The number of OLT cards is determined based on the number of OLT SFPs. * The number of OLT frames and their type is determined based on the final expected number of cards. There should be no cases where optical power levels that are outside the normal ones for the system are used, while respecting the accepted definitions for branching ratios and distances up to 6 km from the OLT terminal. For distances greater than 6 km, the branching ratio should be reduced and an OLT SFP class C+ should be used to ensure the required energy balance. This study was conducted using an Alcatel GPON ISAM 7302 as the OLT for providing broadband services over the GPON infrastructure (Figure 2). Figure 1: Design of the FTTH splitter. The PON network has a point-to-multipoint architecture, in which passive (unpowered) optical distributors (splitters) are used to serve multiple endpoints over a single optical fiber. Passive equipment includes OLT on the service provider side and ONUs on the end user's side. The optical fibers branched through splitters between them constitute an ODN. The goal of using these technologies is to provide a full portfolio of fixed services and to enable next-generation access. Passive modules in the PON include WDM coupler, 1\(\times\)N splitter, optical fiber and cable, connector and ODF/cabinet/rack. The PON was implemented and a new outdoor PON cabinet was installed on a pre-built foundation, according to the manufacturer's instructions (Figure 3). The cable was equipped with multi-fiber push-on (MPO) connectors (9 xMPO8_APC--72 optical fibers) pulled between the cabinet and the shaft in which the general cable organizer (GCO) socket was to be installed. The pulling direction was from the cabinet to the shaft, because the MPO connectors should not pass through conduits and openings. One separate optical cable was pulled for each PON box. Figure 2: Alcated GPON ISAM 7302 provides broadband services via GPON technology, and is part of the ISAM intelligent access platform. The following technical requirements were met during the entire installation process:  
* The PON box and the GCO socket can be installed simultaneously. * The placement of the splitters in the box and the installation of the adapters can be completed in advance. * Before connecting, the MPO connectors are cleaned with a specialized tool. * The GCO socket is installed in a closed car to avoid contamination. * All connectors and splitters are numbered according to the fault discovery protocol. * It is not allowed to leave a technological reserve of cable larger than that required for hanging the box in the volume of the cabinet. In case of excess cable, it is re-drawn and formed at the GCO. * All openings in the cabinet to the shaft are sealed to prevent the penetration of humid air from the shaft and its condensation in the cabinet.