Powerline beyond home networking

04 Nov 2006

Despite years of trials and hype built on the promise of high-speed access over electrical infrastructure, BPL (broadband powerline) has had greater success as a home networking option than a broadband access link. But BPL still has a shot at cracking the access barrier, thanks to - of all things - wireless broadband.

Broadband wireless access technologies are already rolling out across Asia, especially in developing markets, as DSL supplements or substitutes where copper is in sad shape or non-existent. But when it comes to multiple dwelling units (MDUs), wireless broadband runs into problems with indoor coverage, says Dr Ray Owen, director of wireless broadband for Motorola Asia Pacific.

'Getting into the basement rooms of MDUs with wireless broadband with 100% reliability couldn't be guaranteed, because the laws of physics don't allow it,' Owen said.

Motorola's own solution is to beam wireless broadband to the building and then use a gateway to convert the Ethernet signal into a BPL signal that's injected into the building's electrical system. Customers then use a HomePlug powerline modem to access the broadband service.

What makes BPL work in an MDU access scenario, rather than the original idea of transforming entire electrical grids into broadband networks, says Owen, comes down to physics and cost.

'BPL hasn't been successful in the past because the object was to push the signal through the grid and into the home, and they ran into issues such as interference between the data and electrical signals, and they had trouble getting the broadband signal through the transformer,' Owen told Telecom Asia. 'It was also expensive because you had to send people out onto the lines to install the technology.'

With MDU, he explains, 'if you install BPL below the low-voltage transformer, you could use wireless as backhaul to bring broadband to the building and then use BPL to deliver it to every power outlet in the home.'

Co-existence issues
Naturally, Motorola is pairing its Canopy and WiMAX products with BPL, but Owen says the same technique would work with buildings connected to fiber or metro Ethernet links, 'though you'd get better price performance with wireless, especially if fiber or cable hasn't already been installed.'

A potential catch to the BPL option is bandwidth provisioning. HomePlug - the home-networking powerline protocol that Motorola's BPL products support - shares bandwidth with everyone on the same node. So a building running, say, the current HomePlug Turbo standard would have to divvy up claimed peak speeds of 40 Mbps across all tenants.

Another sticking point is standards. HomePlug and rival BPL standards like DS2 and the Universal Powerline Association currently do not coexist or interoperate. Standards bodies like the IEEE and OPERA (Open PLC European Research Alliance) are working on this, while the UPA says it is working with IEEE and ETSI toward the same goal.

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