Original URL: http://www.theregister.co.uk/2006/07/03/uk-wimax-outlook/

WiMAX in the UK. Here's why it won't fly

Spectrum is rare

By Scott Granneman

Posted in Broadband, 3rd July 2006 12:25 GMT

Comment WiMAX is another specification that has come out of the Institute of Electrical and Electronic Engineers (IEEE) in the US, like Wi-Fi which comes under the 802.11 group. There are two variants of WiMAX, 802.16d which covers fixed installations and 802.16e covering mobile use.

Fixed means point-to-point or point-to-multipoint links, for example, connections to buildings that don't move, while mobile is for laptops and covers users moving between base stations - rather like a cellular network.

The technology behind WiMAX actually works, the specification has taken a while to get to fruition but that's helped it in terms of making sure the bugs are out and it can be used in real life.

Many of the issues that plague Wi-Fi networks just can't happen in WiMAX. Networks can grow, users still maintain usable bandwidth, and interference just doesn't occur. WiMAX can easily achieve a usable 75Mb/s across a wireless link.

The original WiMAX specification allowed frequencies in the range of 2GHz to 60GHz, but it's almost impossible to produce radio equipment using commercial processes on silicon that work at the higher end. A modified specification was then introduced, known as 802.16d-2004, which reduced the frequency range to between 2GHz and 11GHz, which is much easier to support on silicon. This is what's known as WiMAX today.

Protected spectrum

The one thing WiMAX mandates is that it uses spectrum all to itself, so someone running a WiMAX network, so no one else can run another network on the same frequency. The network can extend to many basestations which interoperate with each other, and there can be many users utilising the network.

WiMAX has no in-built interference protection. It will assume any other network it comes across is part of the same network and, if it isn't, the network is likely to die, resulting in horrendous data loss.

Wi-Fi on the other hand is explicitely designed to co-exist with other Wi-Fi networks. If there is interference from another WiFi network, each will try and ignore the other or at least minimise the interference they cause each other.

No spectrum (in the UK)

A couple of lucky players have spectrum in the UK, PCCW and Pipex (3.4GHz and 3.5GHz respectively). PCCW bought its spectrum when Ofcom, the UK super regulator, auctioned it, while Pipex acquired it when it bought another ISP (and zero-rated the value of the licence on their books). The frequencies they own sit slap bang in the middle of the WiMAX frequency range, which is pretty ideal for running a broadband service. As they are licensed bands, it also means no one else can use them, so they have a protected service.

PCCW and Pipex will both offer WiMAX-based broadband and have already launched limited services.

Unfortunately, rolling out a large network involves installing a lot of masts (like a cellular network) and connecting everything together - which rapidly becomes very expensive if covering large areas. Since neither PCCW or Pipex really own their own network, they have to buy infrastructure off other players, and that's the largest cost in the network. Though they can roll-out broadband networks, currently their license ONLY allows fixed use (to homes or businesses), so no laptops or other mobile use.

Both companies are likely to be acquisition targets for bigger players which want to roll-out high speed broadband to rural areas and have an existing infrastructure to sit the radio network on.

There are other pseudo WiMAX operators offering service now, but it isn't really WiMAX - most call their networks "preWiMAX" - really a modified Wi-Fi variant called 802.11a.

All these networks operate in 5.8GHz, which is what's known as a light-licensed band. Any operator needs to register their equipment with Ofcom to ensure it doesn't interfere with existing users of that band (mainly government and military satellite links and military radar). There is no interference protection between users. As WiMAX mandates sole use of a frequency, real WiMAX can't operate in 5.8GHz (at least in the UK) with any kind of certainty. Anybody claiming to run real WiMAX in 5.8GHz either isn't, or their network is likely to fall over when somebody installs a US 802.11a system that uses 5.8GHz.

Though Ofcom has the ability to prosecute illegal users of 802.11a (or indeed any other band), no prosecutions (or even warnings) have so far taken place.

Unless more spectrum is released, this will continue to be the state of affairs for a long time.

Spectrum is rare

Ofcom hopes to release more spectrum: there's a consultation taking place now for two x 100MHz bands in 10GHz which could be released in 2007. Unfortunately, as they are at the top-end of the band they have very poor characteristics for WiMAX. The radio signals won't penetrate buildings, so all infrastructure has to be line of sight.

There is the possibility that spectrum could be made available in the 2GHz band, but this is currently allocated to 3G use and it could be a long time before it gets released (as parts of Europe are using it for 3G, there are interference issues to consider - radio waves don't honour national boundaries).

So though WiMAX has the potential to offer high speed broadband access to all, in the UK there's little spectrum and unlikely to be so for considerable time. Pipex and PCCW will launch services, but they'll be "private" networks and WiMAX for the masses is unlikely to happen. ®