Optical/IP Networks

LTE Femtos in the Slow Lane

There's not much point in a Long-Term Evolution (LTE) Femtocell unless a user has a fast enough wired connection in the home to support it.

This was brought home to Unstrung when we talked with Sanjeev Verma, a founder of Airvana Inc. and VP of femtocell business and corporate development, in Las Vegas recently.

Verma's reasoning is fairly simple. All femtocells use a wired broadband connection in conjunction with the onboard cellular radio to provide better cellphone connectivity within a user's house. Cable and DSL connections provide average download speeds of 1.5 Mbit/s worldwide, although speeds in the U.S. are now up over 3 Mbit/s in many areas.

We don't yet know what average download speeds LTE will offer since there isn't a commercial network in the world that actually uses the technology. Operator and vendor tests suggest, however, that upper limits of 50 Mbit/s may be possible. Motorola Inc. (NYSE: MOT) was certainly getting 8-Mbit/s download speeds on an LTE drive at the recent CTIA show.

Forthcoming 3G femtocells, meanwhile, will offer download speeds of 1.4 Mbit/s, and more when High Speed Downlink Packet Plus (HSDPA+) services come in. Verma's point is that 3G will be good enough in this case, and the speed of LTE will likely be throttled by the user's cable or DSL connection.

"It doesn't matter if you have the fastest car on the freeway," says Verma, by way of an analogy. "If you're stuck behind someone doing 20 miles per hour, that's the speed you're going."

LTE deployments -- at least in the U.S. -- could also sweep away another argument for femtocells in the home, that the tiny home base stations improve call coverage. This is because the 700MHz spectrum that AT&T Inc. (NYSE: T) and Verizon Wireless plan to deploy LTE in is said to offer much better signal penetration in buildings.

For its part, Verizon Wireless is pushing ahead with 2G and 3G femtocells, while AT&T Inc. (NYSE: T) is expected to launch its 3G "microcell" sometime soon. Neither, however, have any announced plans for "4G" femtocells. (See MWC Preview: Femtocells Get Real.)

— Dan Jones, Site Editor, Unstrung

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