GPON for dummies :Optical Access Network (Series 1)

  Currently I'm living in Australia and there  are a lot of news about the high speed broadband in the newspaper. I believe the company that does it now is NBN Co. For those who don't know what is FTTH,I'll share a little bit of information on this .I'll separate it to different part  to make things easy. In this part, I'll be explaining in general the idea of the term that widely being use and will go into more detail in chapters to come.

Optical Access Network Architecture

  First and foremost,.What is FTTH, FTTN,FTTB, FTTC or what the heck is all this term?All this term belong to Optical Access  Network architecture .This branch of technology is controlled by major Telecommunication company like Huawei ,ZTE, Alcatel-Lucent ,Ericsson-Marconi . 


                                Figure 1.1 Example of Optical Access Architecture

   Previously, our traditional internet connection using Digital Subscriber Line Access Multiplexer (DSLAM)  type of network architecture. DSLAM make use the existing telephone copper to deliver xDSL service. The preferable distance  from the Central Office (CO) to business premise need to be less than  <5km .I will share the details of xDSL technology limitation on different article.For time being  just understand that copper have limitation in term of Bandwidth vs Distance. In other words , DSLAM can't efficiently deliver it's services to those in rural area that is  more than >5 km from the CO .

  To resolve the issue of Bandwidth vs Distance, we have the not so new technology called Passive Optical Network (PON) and Active Optical Network (AON).I will focus on PON in this article and will write more on the differences on future post. As you can see in above photo ,PON technology used fibre optic to extend the long reach of its service to business premises. Thus this help to resolve the  problem that we have in our traditional DSLAM network.

  From the above architecture diagram,  the fiber is split to external plant from Central Office (CO) using Optical Distribution Network (ODN) .ODN  consist of a passive element that split the fiber to the respective architecture scenario. In real world ODN network is what we see  being installed by the contractor physically by digging/trenching or boring at the footpath . Some of the splitter is left inside the pit and from one pit to the next pit is connected by a pipe.The fiber is lay inside this pipe to reach its destination .In layman term the ODN network architecture is also known as pit and pipe architecture .

 The different application between each architecture is describe  as below:

Fiber to the home (FTTH) consist scenario of
1.single family unit  which able to provide a comparatively small number of ports, including  VOIP, 10/100/1000BASE-T, and RF.

Fiber to the building (FTTB)  :consist scenario of
1.Single business unit which able to provide a comparatively small number of ports such as  10/100/1000BASE-T, RF, and DS1/T1/E1 ports


2.Multi-tenant business unit which able to  provide  a comparatively larger number of ports, including  10/100/1000BASE-T, RF and DS1/T1/E1 ports. xDSL technologies


Fiber to the curb/node (FTTC/FTTN) consist scenario of
1.DSLAM/MSAN (Multiple Service Access Node) which able to provide a comparatively larger number of ports, including  10/100/1000BASE-T, RF, xDSL technologies


  The advantage of deploying FTTN network is  it can save considerable amount of money by not installing fibre optic cable to each premise . Rather, the fiber optics cable can just be install from CO to side of neighbourhood road/curb. FTTN can utilize the existing copper telephone network to deliver it's services .The disadvantage of this is, it will limit the network expansion for future growth and there is possibility of copper deteriorate throughout time .Before deploying FTTN a considerable amount of consideration is needed and understanding on the direction that will be taken by the company for future business growth .

  Beside this few example,there are a different number of design that we can do using FTTN network namely point to point, ring and star type of connection. I will update more about this in later post.

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