Introduction to Passive Optical Network (PON)

Seen from the entire network structures，the Passive Optical Network (PON) market is in a high-growth period due to the ongoing deployments of Fiber to the Home (FTTH) networks.today, we mainly Introduce Passive Optical Network (PON).

What does Passive Optical Network (PON)mean?

A passive optical network (PON) is a cabling system that uses optical fibers and optical splitters to deliver services to multiple access points. A PON system can be fiber-to-the-curb (FTTC), fiber-to-the-building (FTTB) or fiber-to-the-home (FTTH). A PON system consists of optical line termination (OLT) at the communication provider’s end and a number of optical network units (ONUs) at the user’s end. The term "passive" simply means that there are no power requirements while the network is up and running.

A PON consists of an optical line terminal (OLT) at the service provider's central office (hub) and a number of optical network units (ONUs) or optical network terminals (ONTs), near end users. A PON reduces the amount of fiber and central office equipment required compared with point-to-point architectures. A passive optical network is a form of fiber-optic access network.In most cases, downstream signals are broadcast to all premises sharing multiple fibers. Encryption can prevent eavesdropping.upstream signals are combined using a multiple access protocol, usually time division multiple access (TDMA).

Feature

A PON takes advantage of wavelength division multiplexing (WDM), using one wavelength for downstream traffic and another for upstream traffic on a single mode fiber (ITU-T G.652). BPON, EPON, GEPON, and GPON have the same basic wavelength plan and use the 1490 nanometer (nm) wavelength for downstream traffic and 1310 nm wavelength for upstream traffic. most common is 28 dB of loss budget for both BPON and GPON, but products have been announced using less expensive optics as well. 28 dB corresponds to about 20 km with a 32-way split. Forward error correction (FEC) may provide for another 2–3 dB of loss budget on GPON systems. As optics improve, the 28 dB budget will likely increase. Although both the GPON and EPON protocols permit large split ratios (up to 128 subscribers for GPON, up to 32,768 for EPON), in practice most PONs are deployed with a split ratio of 1:32 or smaller.

A PON consists of a central office node, called an optical line terminal (OLT), one or more user nodes, called optical network units (ONUs) or optical network terminals (ONTs), and the fibers and splitters between them, called the optical distribution network (ODN). “ONT” is an ITU-T term to describe a single-tenant ONU. In multiple-tenant units, the ONU may be bridged to a customer premises device within the individual dwelling unit using technologies such as Ethernet over twisted pair, G.hn (a high-speed ITU-T standard that can operate over any existing home wiring - power lines, phone lines and coaxial cables) or DSL. An ONU is a device that terminates the PON and presents customer service interfaces to the user. Some ONUs implement a separate subscriber unit to provide services such as telephony, Ethernet data, or video.

An OLT provides the interface between a PON and a service provider′s core network. These typically include:

• IP traffic over Fast Ethernet, gigabit Ethernet, or 10 Gigabit Ethernet;
• Standard TDM interfaces such as SDH/SONET;
• ATM UNI at 155–622 Mbit/s.

functions are separated into two parts:

• The ONU, which terminates the PON and presents a converged interface—such as DSL, coaxial cable, or multiservice Ethernet—toward the user;
• Network termination equipment (NTE), which inputs the converged interface and outputs native service interfaces to the user, such as Ethernet and POTS.

The Benefits of PON

As early as before, PONs began appearing in corporate networks. Users were adopting these networks because they were cheaper, faster, lower in power consumption, easier to provision for voice, data and video, and easier to manage, since they were originally designed to connect millions of homes for telephone, Internet and TV services.Passive Optical Networks (PON) provide high-speed, high-bandwidth and secure voice, video and data service delivery over a combined fiber network.

The main benefits of PON as below:

• Lower network operational costs
• Elimination of Ethernet switches in the network
• Elimination of recurring costs associated with a fabric of Ethernet switches in the network
• Lower installation (CapEx) costs for a new or upgraded network (min 200 users)
• Lower network energy (OpEx) costs
• Less network infrastructure
• You can reclaim wiring closet (IDF) real estate
• Large bundles of copper cable are replaced with small single mode optical fiber cable
• PON provides increased distance between data center and desktop (>20 kilometers)
• Network maintenance is easier and less expensive

Conclusion

According to the above article, you may have a understanding of the passive optical network.A PON network eliminates the need for switches and a wiring closet, which means fewer points of failure. Fiber-Mart manufactures and offers customized services. any question pls welcome to visit www.fiber-mart.com or contact us.E-mail: [email protected]