Powerline networking and Wi-Fi enable heritage networks

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Powerline networking and Wi-Fi enable heritage networks

Bryan Betts

Historic and ancient buildings present unique challenges for network managers. Many old buildings are legally protected against alteration, and even when they are not, adding more wires can be difficult and expensive. Fortunately technologies like powerline networking and advanced Wi-Fi can help those designing and expanding heritage networks, where often the walls are three metres thick, the wallpaper is handmade and can't be damaged, and you can't lay fibre-optic cables because of the archaeological site under the yard.

At Farnham Castle in Surrey, historic walls two or three metres thick not only make it near-impossible to drill through, but they block out many wireless signals, said Matthew MacLachlan, the castle's programme manager. He added: “The windows are mostly leaded, so you can't even use those.”

Heritage networks follow existing structure

When parts of the castle -- founded by Henri de Blois in 1138, and rebuilt over the centuries as a palace by the Bishops of Winchester -- were converted into a conference centre, its structure dictated what went where. “The offices are where they are because that's where we could get cabling in,” MacLachlan said. “The fact that it already had electric cabling was what allowed us to do any networking at all.”

MacLachlan notes that newer technology has eased the job a little. Better shielding means Ethernet cable can share ducts and underfloor spaces with mains cable. Likewise, when a wireless network was needed, a self-adapting system from Aruba Networks was employed.

But when parts of the castle that had been given non-office uses, such as guest bedrooms in the stable block, just on the edge of Wi-Fi range, also needed network connections, lateral thinking was needed. MacLachlan said it might have been possible to lay cable through an existing underground duct, but the work probably would still have needed listed building consent. 

And given that the duct was a medieval sewer, it is not surprising that he opted for remote access instead, connecting the other building's Aruba access points to the main controller via DSL and the public Internet.

Phil Keeley, a senior systems engineer with Aerohive Networks, has worked on wireless projects at several listed buildings, including Marlborough House and Georgian houses used by Chichester University. He said that while wireless access points still need wires, Power over Ethernet has helped because its lower voltage cable is easier to lay than mains cabling.

Utilising powerline networking

The reverse, Ethernet over Power, known as HomePlug or powerline networking, can also be useful, said Dr Steve Goodwin, a technology consultant with the Houndscroft Partnership. He cites a 100-year-old building now used as offices that, “like most old Cotswold buildings, has three-foot thick Cotswold stone walls largely impervious to wireless. Cabling wasn't an option for various cosmetic reasons so a HomePlug system was the obvious answer."

 “The only problem was that the front and rear of the building were served by separate phases of the mains supply, and HomePlugs cannot work across phases," Goodwin explained. "We used a short Wi-Fi link to join the two HomePlug networks, and this has been working well for about two years now.”

Chris Comley, who runs network integrator Wizards, has used powerline networking successfully too, in one case linking buildings 30 yards apart where “Wi-Fi didn't cut it because of the thick stone walls.” He said there are caveats though: as well as the phase limitation, there have been claims from radio hams -- denied by the manufacturers, of course -- that it generates interference. And he warns that some powerline networking adapters are built cheaply to appeal to consumers, not businesses, so caution is needed in purchasing.

Conquering Wi-Fi challenges

Of course, Wi-Fi problems are not limited to old buildings. Modern buildings often have structural metal, foil-insulated plasterboard and metal-backed doors. Interference problems tend to be horizontal rather than vertical, said Aerohive's Keeley, so depending on a building's protection status, you may be able to provide Wi-Fi coverage via the cellars and attic.

He adds: “A site survey is absolutely critical. In some old buildings, the walls are so dry that RF propagation is better than you might expect. Add the lack of steel reinforcing, and they can even be better than modern insulated plasterboard. It is also seasonal. You need to do your survey in summer when there are leaves on the trees, for example, or you may have an installation that only works perfectly in the winter.”

And in any case, is Wi-Fi-blocking always a bad thing? Aruba's EMEA marketing director Roger Hockaday reckons not: “At least there's no cross-channel interference inside a castle, unlike in an airport terminal,” he said. “Until someone opens the door, anyway.”

--Bryan Betts is a UK-based freelance journalist specialising in business and technology. Read about him at http://www.bryanbetts.com/.


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