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Bill Bennett


Much ado about Super Wi-Fi

For most of us wi-fi is the wireless technology that moves data around the house. Or it might the service you log-on to in a cafe, airport lounge or local hotspot.

D-Link and Microsoft have a plan to use wi-fi as a way of connecting remote areas in poor countries to the Internet.

It’s not the wi-fi you know and love. The two are talking about a standard called 802.11af. You may see it described as “an air interface for white space frequencies”.

In the USA that means snippets of spectrum between 54 MHz and 698 MHz. Europe and the UK use a more modest selection of frequencies between 490 and 790 MHz. Much of this spectrum is already used in New Zealand by 4G cellular networks.

Super Wi-Fi potential

In theory the channels in these frequency bands can each take a few dozen Mbps. Engineers say they can bond the channels together to deliver a total bandwidth of more than 500 Mbps. Again, that’s theory.

Like all wireless bandwidth, it has to be shared between all the users, but bandwidth isn’t the most important aspect of the technology and the chosen spectrum band. Radio signals at these low frequencies can travel long distances. Engineers designed the  802.11af standard for signals to travel up to 1km from a single access point.

In other words, Super Wi-Fi isn’t going to compete with fibre or 4G cellular except, perhaps, on cost.

While 802.11af is designed as a point-to-point service, D-Link and Microsoft are keen to talk about operating mesh networks in places where there is no existing internet infrastructure. They say these will be used for voice phone calls as well as data, but these days there’s no real distinction between the two.

No doubt some small-scale rural broadband providers in New Zealand are checking the 802.11af specification as you read this. Perhaps it could be useful in more extreme remote locations. However, there’s a lot of work still to do. The af standard is still a work in progress.



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