Can’t we do this all on Wi-Fi?

At least once a day, someone comes up to me in the NBN Co Discovery Truck and asks to know why we need to build the NBN when we can all just use Wi-Fi!

This is, in my mind, a fair and logical question given almost everyone is using devices that are wireless now - including tablets, smartphones and laptops.

So why are we building a "fixed line" optical fibre network?

The reason is that when we're talking about WiFi, "wireless ain't wireless". What I mean by that is that although your tablet or laptop might be connected wirelessly through Wi-Fi, the Wi-Fi is almost always hooked up to a fast fixed-line connection like ADSL, cable or fibre.

Certainly, if you're out and about, your device might be connected to a mobile broadband network like 3G or 4G, but you'll also notice that your speed and coverage fluctuates; and you might be presented with messages like "this app exceeds 50MB, please connect to Wi-Fi to download it".

Your home or office Wi-Fi, connected to a fixed-line, almost always offers a stronger and more consistent connection than 3G/4G mobile broadband.

So now we know that Wi-Fi is usually a fixed line connection (and you'll still be able to use it with an NBN connection provided you have a Wi-Fi router), the next question that people ask is: "why can't we build a national network using mobile broadband?"

While mobile technology is wonderful for internet use in those gaps of time when you're away from a fixed line connection, it has capacity limitations that mean it's not the best option for building a high speed national network for everyone's full-time internet usage.

Let's look at speed.

At the moment,  NBN Co is offering its retail service provider customers wholesale speeds of up to 100Mbps over fibre, but we are already planning to provide wholesale speeds up to 10 times faster -- up to 1Gbps over fibre.

The high capacity fibre cables at the core of the NBN transit network are capable of transmitting data at a staggering 9.6 terabits per second - more than 100,000 times faster than a home 100 Mbps connection.

Research trials are achieving 69 terabits per second over a single 240km strand of fibre, so there's clearly enormous room for growth in speeds over fibre as people's internet usage grows.

The great thing about fibre is that once it is laid in the ground, getting faster speed from it doesn't require re-laying the fibre; it just requires the equipment at either end of the cable to be swapped out and upgraded in the future.  

However, with mobile broadband technology, each user has to share speed in each mobile coverage cell, which means the more users there are, the slower the speed and capacity for each user.

It's all in the delivery!

To describe how we are delivering high speed broadband I like to use the analogy of our roads. We are laying the roads that will connect 100% of the country, allowing us to communicate with anyone and everyone, faster and more reliably.

As technology continues to advance and our "cars" continue to improve they will still run over the same roads (fibre, fixed wireless and satellite.)

However, unlike roads, the NBN fibre  can add "lanes", as well as raise the "speed limit" much more easily and cheaply (and completely safely)!

According to some industry observers, mobile broadband capacity  is dangerously close to running out. Wireless analyst Peter Rysavy found that demand for mobile broadband is likely to surpass the spectrum available by mid-2013.

So, even if we wanted to invest in mobile broadband technology, there's only so much spectrum to go round. In fact, a fixed line network will relieve some of the burden on our mobile networks and help both networks to continue working efficiently. Vodafone Australia's Matthew Lobb confirms this, saying, "getting fixed line right is absolutely crucial for mobile networks."

One final point mobile broadband: according to an article in The Australian, to build a wireless network with even a fraction of the maximum wholesale speeds and capacity as a fibre optic network that would work efficiently in crowded metro areas, we would need a mobile tower every 500 metres.

"In order to get those 100Mbps speeds and beyond you'd need to be installing a base station around about on every suburban block," says Narelle Clark, Vice President of the Internet Society of Australia and board of trustees member of the Internet Society globally, quoted in Crikey.

That is a frightening thought!

Mobile broadband and fixed line technologies are important for telecommunications in Australia, but both are complementary to each other.