GPON for dummies : Passive Optical Network(PON) Standards . (Series 3)

   I have explained in detail  on differences between Passive and Active Optical Network in my previous post .In this post, I will continue to write on Passive Optical Network (PON)  technology standard.

PON network (cont)

Figure 3.1 GPON network model

   The figure above show the model of GPON network. OLT is located in Service Node Interface (SNI).OLT is  the starting point for GPON network and is connected to Service Node.  OLT is a power equipment that manage and distribute data from and to subscribers .OLT uses Gigabit Ethernet technologies to transmit and receive data from Service Node . An example of  Service Node is a router .

   OLT is connected to Optical Network Unit (ONU) through Optical Distribution Network (ODN)   .ODN use Wave Division Multiplexing (WDM)   technology to transmit data from OLT to ONU. GPON use different wavelength in WDM to transmit and receive data for its uplink and downlink .I will explain more details on GPON fundamental in the next post. The  fiber is then split and distribute to  subscribers premises using passive optical splitter .Passive optical splitter normally is located by the road side either inside a manhole,duct or a pit . There are different type of  Optical Distribution Network (ODN)  deployment depending on how Service Provider plan to do it.But the main  idea remain the same in which to connect the physical layer of the network from OLT to ONU.

  ONT on the other hand is located in User Network Interface (UNI) and is terminated at premises end. It provide FE,E1,T1,POTS and others for the subscriber service usage

PON Standards


   PON standard is divided to two, EPON and GPON. EPON is a technology base on ethernet and GPON is a technology that gradually developed from Asynchronous Transfer Mode (ATM) transmission.Both of these technology have their own strength and weakness depending on what Service Provider plan to do in their network.



 Figure 3.2 show the relationship between EPON and GPON standards

APON: ATM Passive Optical Networks
EPON: Ethernet Passive Optical Networks
GE-PON: Gigabit Ethernet Passive Optical Networks
GPON: Gigabit-capable Passive Optical Networks
  
Below diagram show the differences between EPON and GPON .



Figure 3.3 :Difference between GPON and EPON



Why GPON is prefered over EPON?



Figure 3.4 



Between both technologies, GPON is preferred by global Service Provider because of several reason .

1. Longer transmission distance: Transmission over optical fibers reaches the maximum of 20 km transmission distance.

 2. Higher bandwidth: downstream 2.5 Gbit/s and  upstream 1.25 Gbit/s (the PMD layer) for each subscriber
     
 3. Optical split feature: The single optical fiber from the CO is split to multiple drop optical fibers to save the resources.

4.GPON supports the triple play service. It provides full-service solution to solve the bandwidth bottleneck of twisted pair access, and to meet the requirement for high-bandwidth services, such as high definition TV and live show. GPON is the best choice for the triple play service.

5.Complete GPON standards and high technology requirements



That's it for now. :-)

  In the next post, I'm going to share more details on GPON fundamental technology.Stay tune. What do you think about this post? Please left comments in box below.



Read Pervious:GPON for dummies:Basic Passive Optical Network Concepts

Previous
Next Post »