17/11/2010

Ofcom consultation on "whitespace" use and Gelocation

There's lots of spectrum around, but it's a crowded space and so much of it is licensed by Ofcom i.e. in order to utilise equipment that transmits or receives data in that spectrum a "use" license is required. This is why a TV license is required. Mobile phones also require a license, but that's paid as part of the license that the mobile network operators have (and have paid for).

Various parts of the spectrum have been made license exempt such as 2.4GHz which is used by WiFi (802.11b/g/n), Bluetooth and other systems like Zigbee. Licenses exempt status means that a user doesn't need to get a specific license if they use the equipment in accordance with the rules that Ofcom have published (i.e. Ofcom publish a "blanket" license and as long as the equipment in use doesn't get used outside the licensing framework, then the use doesn't need to get a license themselves). Any WiFi or Bluetooth systems will comply with Ofcom's licensing regime.

In the past Ofcom has bowed to public pressure and made certain equipment license exempt such as low power FM transmitters than can connect to MP3 and other music devices and transmit a short range to a radio (usually in a car). As they're low power, they wont interfere with the commercial radio stations (at least to other users) who have paid a lot of money for the licenses to transmit in the commercial radio bands.

Another big chunk of spectrum is in the TV bands and some of this is reserved so that interference between bands doesn't happen. The TV bands have much better propagation characteristics than say 2.4GHz which is used by WiFi and Ofcom are looking at ways of using the "dead" space for short-range low power devices which could be used say to transmit video signals between systems in the home. The whitespace could also be used for higher power rural broadband access.

They would work by looking at the bands and finding these dead areas known as whitespace and then those frequencies would be potential candidates for local transmission. However this could rapidly lead to interference between neighbouring systems (say in a neighbours house), so Ofcom wants the systems to consult a geolocation database (hosted by Ofcom) that the system could register with and ensure the whitespace was suitable for use in that area.

There would be a "master" device that would communicate with Ofcom's database and report the power and frequencies it was using and any connected devices (slaves, that wouldn't need to connect to the database themselves). The whitespace devices will be license exempt. Though Ofcom will initially run any database required, they don't evisage running the database in the future as that is best left to commercial organisations and Ofcom would like interested parties to contact them.

Though Ofcom are consulting now (the consultation runs from 09/11/10 to 07/12/10) they don't expect whitespace devices to appear until 2014.

Interested parties can respond to the consultation on-line.
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