FTTH PON splitting ratio and level
Single Splitting, Two-level Splitting, Multi-level Splitting, Splitting Ratio, Central Office (CO), Customer Premises Equipment (CPE)
As the diagram descriped, consisting of an Optical Line Terminal (OLT) that is located in the Central Office (CO), the optical network with the optical power splitter and finally, the Optical Network Unit (ONU) as the Customer Premises Equipment (CPE).
During the deployment of fiber to the home passive optical network (FTTH-PON), usually, we will face some physical access network design problems.
Splitting Ratio Principle and Solution
Optical splitter, also known as beam splitter, is one kind of integrated waveguide optical power distribution device based on a quartz substrate. A fiber splitter is one of the most important passive components in the whole FTTH network system.
There are two types of splitters in our current FTTH application, their splitting ratio principle are as following:
- FBT SPLITTER makes two (two or more) fibers removed the coating layer gather in a certain way, stretched to both sides under the heating zone at the same time, form a double cone’s special waveguide structure finally for getting a different splitting ratio via controlling length of the fiber torsion angle and stretch
- PLC SPLITTER is a micro-optical element using photolithographic techniques to form optical waveguide at medium or semiconductor substrate for realizing branch distribution function.
Based on our EPON/GPON project experience, two main splitting ratio solutions as following:
- When the splitting ratio is 1:32, your current network can receive qualified fiber optic signal in 20Km.
- If your distance between OLT and ONU is small, like in 5Km, you can also consider about 1:64.
PON is a point-to-multipoint fiber optical network with no active elements in the signal’s path. It consists of a single, shared optical fiber connecting a service provider’s central office (CO) to a passive splitter, which can accommodate multiple optical connections with customers. The PON splitting may be achieved by single splitting or by multiple/complex splittings (two-level) distributed splitting. The splitter of single splitting demultiplexes a downstream signal into, for example, 32 subscriber streams.
Accordingly, the PON access network with single splitting forms a double-star topology with the first star at the CO and the second star at the splitter.
- Single splitting: between FTTH OLT and ONU only existed a single splitter.
- Two-level Splitting: between the OLT and ONU existed two splitters in series.
- Multi-level splitting: between OLT and ONU existed multiple splitters in series.
The Single Splitting solution is usually used in crowded city center or town areas, in order to reduce cost and easy to maintain the optical distributed network (ODN) nodes.
In the other hand, Two-level and Multi-level Splitting solution is used in curb or village places, to cover widely ODN (optical distributed network) nodes, conserve resources and save the money.
–Special thank to FTTH-PON Splitter Location-Allocation Problem (Youngho Lee, Youngjin Kim, Junghee Han)