Consumers will have to share small, inexpensive cells in their homes with nearby mobile users to affordably meet the growing demand for mobile data in the next decade, a Qualcomm executive said Tuesday.
"There really is no alternative," said Matt Grob, Qualcomm's executive vice president and chief technology officer, during a presentation at the Qualcomm On conference in Santa Clara, California.
A reference design for such a cell, which Grob showed during the speech, would fit in the palm of one's hand. It could cost less than a cellphone and might be integrated into set-top boxes, game consoles, home broadband gateways and other devices, Grob said.
Shared in-home small cells are only one part of Qualcomm's vision for increasing the capacity of mobile networks. Within about 10 years, networks will need about 1,000 times as much capacity as today's traditional macro cells alone provide, according to Qualcomm. Like mobile operators and the rest of the industry, the company also believes more radio spectrum needs to become available for mobile. For example, Qualcomm advocates mobile users sharing the 3.5GHz band, which might be used for its in-home small cells.
But adding more spectrum will only increase capacity by about 10 times, Grob said. The remainder of the boost will have to come from other steps, namely deploying more, smaller cells to reuse the same frequencies more efficiently. Carriers also are planning smaller cells, with AT&T making one of the biggest commitments to that approach in the U.S.
But Qualcomm's concept, which it has discussed with AT&T, goes beyond the common industry vision of carrier-deployed small cells in buildings and dense public areas. Among other things, in-home small cells could reduce the cost and complexity of deploying public small cells and linking them to wired networks, Grob said.
Many consumers already use so-called femtocells, which are essentially small, in-home cellular base stations supplied by mobile operators solely for a family's use within their own walls. One challenge femtocells raise is interference with macro cells and other femtocells if they project their signals outside the home.
Qualcomm essentially wants to turn a femtocell's outdoor signals from a liability into an asset.
"An interesting thing happens," Grob said. "A little bit of that signal leaks outside and starts to provide little pieces of coverage outdoors. And if enough of it is happening indoors, then pretty soon you end up with pretty good outdoor coverage."
At the heart of its vision is UltraSON, an implementation of SON (self-optimising network) technology that Qualcomm would use to turn many cells spread across a neighborhood into a unified network. Coordinated operation can not only prevent interference but can turn the indoor cells into a usable network.
The company has deployed the technology in an actual neighborhood and shown good results in terms of outdoor coverage, Grob said. Even in the weakest coverage areas there, outdoor users got 700Kbps (bits per second), according to Qualcomm. When combined with the effect of making 3.5GHz spectrum available, carriers could achieve the 1000x improvement in network capacity if one out of five homes in an area had a publicly available small cell, Grob said.
However, sharing in-home cells raises its own issues. The traffic that goes through such cells reaches the larger Internet over the consumer's broadband connection. Where the provider of broadband is the same as the mobile operator, it may be relatively easy to build a business model that satisfies both the subscriber and the mobile and wireline provider. Where the resident's mobile service comes from a cellular carrier and the wired broadband is from a cable operator, it may be more complicated.
Grob said he's hopeful that Internet service providers and mobile operators will find business arrangements that work. Subscribers who make their home cells available to others might get a variety of different incentives to do so.
One possible business model is "reciprocal access," in which users who make their home networks available get access to other participants' networks when they pass by their homes. Fon, a Spanish service provider, offers a similar program to consumers who choose to make their home Wi-Fi networks publicly available.
Alternatively, carriers could offer access to the home cells for a fee, similarly to hotel Wi-Fi, with the resident enjoying the fruits of that business in some way. A third possibility would be for wired broadband providers, such as cable companies, to build the small cell into a set-top box or home gateway and offer that to mobile operators on a wholesale basis.
The technology to secure a shared in-home cell and to reserve a certain amount of bandwidth for the resident already exists, Grob said.
However, on top of business issues, some of these arrangements could introduce new complexities to both home broadband and mobile services, IDC analyst Will Stofega said in an interview after the presentation. Most service providers already have a complex set of metering, billing and accounting systems even without having to credit subscribers back in some way or manage new arrangements with other service providers. Making all the pieces work together might be a real challenge, he said.