Original URL: http://www.theregister.co.uk/2010/11/03/wi_homeplug_alliance/

Wi-Fi strikes alliance with mains networking tech

There's parts of the spectrum we're not polluting yet

By Bill Ray

Posted in Broadband, 3rd November 2010 11:51 GMT

The Wi-Fi Alliance has inked an agreement with the HomePlug Powerline Alliance to create interoperable kit, capable of annoying radio hams as never before.

Power line telecommunications (PLT) kit sends networking signals around the home over mains wiring, and often competes with Wi-Fi, which uses radio to achieve the same thing. But now the biggest certification bodies in both fields are joining forces to certify interoperable kit that will be able to pop up a hotspot in any room once it's plugged in.

Such a device isn't on the cards just yet - right now the agreement is just a promise to "facilitate interoperability between Wi-Fi equipment and devices connected to powerline home network", though there is a nod to the future with the plan for a "joint technical review of Wi-Fi Alliance and HomePlug specifications and standards that facilitate interoperability of smart grid application".

Wi-Fi kit kicks out networking signals in the unlicensed 2.4GHz band, but that frequency is getting overloaded and has real trouble getting through walls - particularly in non-timber-framed houses where the internal walls are expected to take some of the strain. PTL uses much lower frequencies, and doesn't need a licence as the transmissions are sent down mains wires rather than through the air.

But mains wiring isn't shielded, so the signals leak out. When the frequency is really low it only upsets radio hams, but the frequency is increasing as the manufacturers try to squeeze more data down the line. Increasing the frequency puts leaking PTL into the realm of aircraft radio, not to mention Radio 4.

The most obvious outcome of this agreement will be PLT kit that you just plug in to create a Wi-Fi hotspot in every room - which is fine as long as you don't mind upsetting the Civil Aviation Authority, the BBC and a lot of bearded hams. ®