Overcoming that pesky antenna problem with a mini cloud RAN
via Flickr © Thomas Rousing Photography (CC BY 2.0)
One of the companies that drew attention at Mobile World Congress this year was Airvana which was showing off its ‘OneCell’ solution for indoor coverage and won the GSMA’s Best Mobile Technology Breakthrough award.
Ever since 2G, indoor coverage has been a big problem for mobile operators because as the new mobile network technologies creep up the spectrum range their ability to bash their way through walls creeps down.
A traditional fix in offices and factories has been to install Distributed Antenna Systems (DAS) which sounds like a sensible move except that DAS systems are expensive to install and expensive again to upgrade.
Small cell technology might look like an attractive answer, but it too has complexity problems (difficult to engineer handover between rooms and can involve complex RF planning and interference from the ‘macro’ cells outside). Because it involves multiple small cells, it too is expensive.
Against this background, then, Airvana’s OneCell solution seemed to be just that… a solution. It’s an application of “cloud RAN” technology where you have a single baseband controller connected to radio points distributed through different rooms (or clusters of rooms) in the building. The difference is that the radio points all meet up at the controller to form a single cell, so you don’t get all those interference and handover problems.
That’s the system on paper - do the economics actually work out in the field? Airvana has sensibly (perhaps bravely) got an independent outfit to work it all out and do the sums. Real Wireless has produced a report that finds that Airvana’s Cloud RAN small cells can save up 69 per cent of the costs usually accrued by DAS installations.
According to Airvana, “The study examined the use of C-RAN LTE small cells as an alternative to LTE DAS in both upgrades of existing DAS and in new “greenfield” DAS deployments. Both large and small building deployments were analyzed, and both active and passive DAS.
The study concluded that Cloud RAN small cells were less expensive in all the scenarios it considered, including multi-operator deployments where DAS has previously been considered superior to small cells.
In summary, the analysis found that many of the savings of the OneCell C-RAN approach were due to its “Wi-Fi-like” deployment model, which kept costs low by using standard Ethernet LANs for in-building distribution rather than fiber/coax cabling and remote radio heads. This won the Airvana approach both lower costs and the flexibility to add and redistribute capacity in response to changes in user demand.
The full white paper, exploring the analysis and results in detail, is available at: www.airvana.com/c-ran-economics/