Posted by: miniflex | March 15, 2010

Easy guide to FTTH

Who will find this guide useful?

This guide is designed to help everyone newly involved in making decisions about Fiber-To-The-Home, such as those communities interested in responding to Google’s recent Google Fiber campaign and ‘Request for Information.’

We have simplified many of the core topics so you can quickly get to grips with the key processes and make your decision-making process easier.

What actually is FTTH?

FTTH, or Fiber-To-The-Home is the method for deploying optical fiber cable from the center of nationwide networks to the front door of your home. Fiber cable is already commonly used up to the point of your utility exchange and sometimes right up to the utility cabinets in your streets.

Diagram of FTTH
Fig. 1 – Scope of an FTTH deployment

As you can see in the above diagram, FTTH is the physical process of replacing or upgrading copper telecoms wiring that comes from your local exchange or cabinet, with optical fiber cable.

Why do we need to know about FTTH?

FTTH is the new way of bringing the internet, television and other broadband services into the home. It is only recently that the technology has become affordable for worldwide deployment. However, we need to be aware of the different challenges FTTH poses.

Why should we use optical fiber?

Copper wiring is limited in its ability to handle large volumes of data traffic. The ability to carry information is called bandwidth. Lots of bandwidth allows huge amounts of information to be carried. One fiber cable can carry many different streams of data and therefore deliver much more bandwidth than copper can.

What does FTTH mean for end-users?

People with FTTH connections will be able to have a really fast broadband service which means downloading films will take minutes rather than hours. It will make interactive activities like gaming instantaneous and more enjoyable. Working from home will be easier. Fiber cable provides a reliable and faster connection to the outside world.

Installing FTTH

There are 4 main steps for installing fiber cable to the home.

  1. Place ducting between the home and the cabinet or user access point (a small consumer unit closer to individual houses, see Fig. 4)
  2. Install the optical fiber cable into the ducting.
  3. Connect the optical fiber cable to the home.
  4. Connect the optical fiber cable to the cabinet or user access point.

Step 1 – Installing ducting

Ducting, which is a protective conduit much like electrical trunking, will need to be installed between the cabinet and the home. This can be at any time prior to installing fiber cable and can be designed and built into new and existing premises. The ducting acts as a pathway for the fiber cable to pass through as well as providing protection for the fiber cable.

Ducting for Optical Fiber Cable
Fig. 2 – ‘Microduct’ ducting for optical fiber cable

Step 2 – Installing optical fiber into the ducting

There are three main methods for installing fiber cable through this ducting:

Pushing cable:
Pre-connectorized fiber cable can be pushed either manually or using suitable equipment from the home to the cabinet.
Pros: This method is quick, cheap and relatively hassle-free.
Cons: Limited to a certain distance that fiber cable can be pushed over.

Pulling cable:
Pre-connectorized fiber cable can be bundled with a pulling string and pulled from home to cabinet.
Pros: Traditional method for installing short lengths of fiber cable.
Cons: Greater risk of damaging cable and more time consuming than pushing or blowing.

Blowing cable:
Blowing fiber cable is when fiber cable is pushed using a specialist pressurised rig to blow the fiber cable down the duct.
Pros: Very fast, minimal damage to cable, can be used over great distances.
Cons: Specialist equipment and man-power required, messy due to debris blowing through duct, requires air-tight connections. Needs skilled personnel to do it and finish the connection process to the home.

Step 3 – Connecting the optical fiber cable to the home

If the fiber cable is pre-connectorized, it will need to be connected to the equipment provided by the internet service provider by the user or an engineer.
If the fiber cable is not pre-connectorized, an engineer will be required to make this connection.


Fig. 3 – Optical fiber cable, pre-connectorized with industry standard SC connector

Step 4 – Connecting the optical fiber cable to the cabinet or user access point

Once your ducting has optical fiber cable in place and has been connected in the home, the only thing left to do is to connect it to the cabinet or a user access point.
There are two methods for this:
If the fiber cable is pre-connectorized, the process is easy. Simply assemble and plug the connector into the appropriate port in the cabinet or connection unit. A network technician may be required for this.


Fig. 4 – Making a subscriber connection to the user access point

If the fiber cable is not pre-connectorized, a connector must be ‘spliced on’ by a qualified and highly trained technician. This involves polishing and joining the fiber to the one coming from the connector.

Points to remember:

Optical fiber cable must be bent in a controlled manner

As an optical fiber is made of glass, or occasionally plastic and is approximately the thickness of a human hair, it is much more delicate than standard copper wiring. As signals are carried as light and not electricity, great care must be taken when bending or joining the fiber as imperfections affect the performance dramatically.
Because the glass optical fiber can break, or the light can escape if bent too far, optical fiber cable must be protected against tight bends and kinks when it is installed or handled. For this reason, fiber cable must be installed with a degree of care and planning.

Bend Radius
Fig. 5 – Diagram showing an example of the maximum bend radius of an optical fiber cable
When planning the route that the fiber cable is going to take, from the ground or the pole into the home, you must ensure that the fiber cable does not have to bend more than necessary as this will impair the performance. It is important to keep the total number of bends as few as possible.

Plan and measure the length of fiber cable required

Optical fiber must be cut and prepared in laboratory conditions and is therefore normally supplied in pre-cut and pre-connectorized lengths.
This means that when planning your installation, you need to think about the length of fiber cable needed. You cannot cut the fiber cable to length without the services of an engineer, so you must choose the correct length for your installation.

Summary

This easy guide to FTTH is to get you started and to show you that understanding optical fiber is straightforward.

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Responses

  1. There is only one point I feel is under-stated: What does FTTH mean for end-users?

    It is not just about downloading movies faster, or being able to work from home (although this will be delicious!). It is far more about all of the new services that will become possible.

    For instance, telehealth applications so you can sit on your sofa and be checked over by your consultant; telepresence e.g http://www.youtube.com/watch?v=jAIDXzv_fKA; remote education, and SO MANY more we cannot begin to imagine yet.


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