Fibre Vs Copper

What is FTTC, how does it work, and why is it the future?

What is it?
Fibre To The Cabinet (FTTC) is where fibre optic cable is used to transmit signals between the telephone exchange and the street side telephone cabinet.  This can offer much higher speeds – 100 Mbit/s downstream over 24 Mbit/s (the current maximum broadband speed in the UK over copper wire) and much more bandwidth – a single twisted copper pair wire can deal with 6 phone calls, whereas a single fibre pair can deal with 2.5 million phone calls.

How does it work?
Some knowledge of fibre optics and how they work is necessary to understand this.  As this is knowledge I did not have before today, I would like to thank – for helping me out here.

Fibre optics are long thin strands of very pure glass.  They are arranged in bundles called optical cables and are used to transmit light signals over long distances.

There are two types of optical fibre, single-mode or multi-mode.

Single-mode fibres:

  • Have small cores and transmit laser light

Multi-mode fibres:

  • Have larger cores and transmit infrared light from LEDs

Light travels through the core (which has a high index of refraction) by constantly reflecting from the cladding (which has a lower index of refraction) by using total internal reflection.

This works in fibre optics as the angle of light is always greater than the critical angle.  Thus light reflects from the cladding no matter what angle the fibre itself gets bent at.

The cladding does not absorb any light from the core so the light wave can travel great distances.

However some of the light signal does degrade within the fiber, mostly due to impurities in the glass.

The process of communicating using fibre optics involves the following:

Why is it the future?
Currently the UK is lagging behind other developed countries in the broadband world.  A typical household in the UK has an average broadband download speed of 4 Mbit/s, compared with South Korea, where the average household has broadband with download speeds of almost 50 Mbit/s.  Research conducted for Cisco in autumn 2009 placed Britain 25th out of 66 countries in terms of the quality and reach of its broadband networks.

This is due to the fact that the majority of broadband customers in the UK get their data from copper wires as opposed to fibre.  Information is transmitted via electrical signals in the copper wire.  However the copper resists the electrical signal, which results in the speed decreasing over the length of the wire.  Thus the further away a household is from their local telephone exchange, the slower their broadband speed will be.  This is because copper was designed to carry the human voice, not massive chunks of data.

This is not sustainable for the future and fibre optics are seen as the best alternative.  The main blocker is the amount of money required for this change (predicted to be several billion pounds).  The government will not (or cannot) commit the funds needed to push this forward; they have pledged to commit only £530 million (until the next spending review which will commence in 2012) towards this cause, which analysts have claimed is “not nearly enough”.  Point Topic Chief Analyst Tim Johnson compares this commitment with that of the French government.  They have pledged £570 million per year between now and 2025 to improve their broadband – this is more per year than the UK is pledging for the whole spending review period.

The alternative is for broadband companies to fund the new infrastructure themselves.  If this happends they will need to compensate by charging customers more for broadband services.

So is it worth replacing the copper wire infrastructure with optical fibres?

Optical fibres are better than copper wires for the following reasons:

  • Less expensive
  • Thinner
  • Higher carrying capacity
  • Less signal degradation
  • Multiple signals in the same cable do not interfere with each other (this means clearer phone signals and TV reception)
  • Low power
    Digital signals can be transmitted easily
  • Non-flammable (because no electricity is passed through them)
  • Lightweight
  • Flexible

There is an argument that offering FTTC is not enough to keep up with the high broadband speeds and high bandwidths offered in other countries which use Fibre To The Home (FTTH, also known as FTTP – Fibre To The Premises).  This can offer speeds of up to 100 Mbit/s.

FTTH is the fastest form of fibre as it uses fibre all the way to the household, whereas copper wire is still used in FTTC to take the signal between the cabinet and the home.

BT Infinity is a BT initiative to roll out FTTC across Britain.  This promises 40 Mbit/s, with a target of reaching 10 million UK homes by the 2012 Olympics.  This is certainly a quick deployment, mainly because the existing copper will only be replaced up to the street cabinet level and no further.  This will also include replacing the electronics at the exchange with miniaturised cards within the cabinets on the street – effectively moving the exchange much closer to the customer.  However this is still slower than the current offering from Virgin Media, which gives 50 Mbit/s.

Elfed Thomas, the CEO of i3 Group – the parent company behind the Fibrecity projects – claims that only aiming at FTTC will mean an uphill struggle in the future when faster broadband speeds still are needed.  The i3 Group recently funded a £30 million project which turned Bournemouth into the UK’s first Fibrecity.  This used their patented technology to deploy a fibre network through the waste water infrastructure in the sewers which is then brought to homes and businesses via micro trenching systems.  This is a fast and low cost way to lay fibre optic cables without having to dig up lots of roads.

The chief executive of BT does not agree.  Ian Livingstone sees the difference between his company’s 40 Mbit/s FTCC plan and a 100 Mbit/s FTTH system as similar to that of a Ford and Ferrari – most people are happy with a Ford.

I agree with this in theory.  And while it is almost definitely true that most of those Ford owners would upgrade their model for a Ferrari if they could, most people would choose not to because of the extra cost.  Similarly, BT do have a Fibre To The Premises option, but availability of this will depend on demand as it will be expensive.

So what we really want is the Ferrari, but at the price of the Ford.


About RNewstead

I am learning every day. Sometimes I worry there are too many interesting things in the world and not enough time.
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