UK allows 5.8GHz operators to pump up the power

Total Telecom reports that Ofcom is altering the power rules that govern the use of wireless equipment operating at the 5.8 GHz band in the UK, supposedly to "address the digital divide"

"[Using the 5.8 GHz band] is simply another way of providing broadband other than LLU or cable," said an Ofcom spokeswoman, speaking to Total Telecom on Monday.

Ofcom said that upping the power limits will extend the geographic reach of broadband services on the 5.8 GHz band, meaning more remote and rural areas will have access to high-speed Internet.

Now (a) it is great to see that the UK are allowing use of 5.8 GHz in the way they are:

According to Ofcom, the use of equipment in the 5.8 GHz band is subject to a light licensing regime that allows terminals to be registered with the regulator online.

The spokeswoman explained that the 5.8 GHz band needs only a minimal amount of regulation to protect it from illegal interference.

and (b) it is good to see regulator exploring ways to make better use of existing technology, but can one really call this a divide?

The report showed that 41% of adults living in rural areas have broadband Internet at home compared to 45% of adults in urban areas.

Tsk,tsk... can't have the lads in rural England lagging by 4% now can we?! ;)

But!:

The increase from 2 to 4 watts will lower the cost for operators intending to use the spectrum to deliver fixed wireless broadband services, the U.K. regulator said.

Now as far as I can recall from my days as an Elec Eng student, propagation of electromagnetic signals (using an omnidirectional and not a directional antenna) follow an inverse square law?  Which means doubling the power will increase the reach by only about 40% or so?  And as there is no indication of this use of 4 watts is restricted to urban areas, will doubling the allowable power not cause chaos in urban areas where previously workable solutions will be rendered inoperable?  Will this really make the deployment of rural WiFi networks @ 5.8 GHz more affordable and thus kick that 41% penetration of broadband up significantly?

Maybe the likes of Joe @ Amobia will have some answers for me?

Comments

[DaveG]

Thanks for that Paul - seems worth it then. With a broadband penetration here of less than 5% I still have a problem seeing the issue of the "digital divide" from 41% to 45%! ;)

[PaulR]

Your right about the inverse square law, the range of the signal only increases by 41% but this is significant for rural links where the distance is such that the signal strength at the user end is low enough to have the raw rate backing off. The extra power could double the effective bandwidth depending on the sensitivity thresholds.
I design outdoor wireless links based on 802.11a for a living, so I know that those that comply with OfCom's specifications for use in the 5.8GHz band won't cause the type of urban interference that you talk about. The reason why is the requirement to implement TPC and DFS, which are over and above standard 802.11a. TPC (Total Power Control) backs off the transmit power so that the link only uses enough power to satisfy the link. DFS (Dynamic Frequency Selection) should ensure that the unit plays fair with the spectrum, especially for coexisting with MOD radar that just happens to operate at the same frequency.
Unfortunately, most installers are using generic US 802.11a gear, or even WiMax, which don't support the OfCom requirements and, as such, are illegal. Very annoying for those of us who went to the trouble of developing the required features and, since the whole thing is policed by complaint, difficult to track down illegal use.

[DaveG]

Thanks Joe

"...rural is simply pre-urban." ?!? you sound like a manic property developer... is your colo project giving you land-baron ideas!? ;)

Agreed on the 'freedom to innovate' - do we have the ability to good corporate citizens and work together to avoid undue interference between networks though?

[Joe]

Hi Dave

I'm guessing this change is in response to a request from the network operators in the market.

Everybody agrees that high power omni's in urban or rural areas are bad.. if you take the long term view where rural is simply pre-urban.

For directional links this could be useful.. building a 50Km link rather than a 35Km link would be nice.

In the end I think the key is to allow equipment vendors and network operators more room to innovate.