When you talk on a cellular phone, you’re sharing radio frequencies with everyone else who’s using one within a three-kilometer radius of the nearest base station. As everyone knows, this sharing doesn’t always work perfectly – network congestion can lead to static, dropped calls, and slow data downloads.
But what if you didn’t have to share a cell-phone signal? What if the nearest base station could aim a radio beam directly at your phone as you moved around, rather than spewing signals in all directions? In that scenario, you could expect clearer voice calls and speedier delivery of digital information such as Web pages or video. And by sending out multiple beams, your cellular carrier could deliver enhanced signals to other customers, too.
This approach to increasing the capacity of cellular networks is called “adaptive beamforming.” And engineers at Nokia are quickly bringing it closer to commercial use. Although the Finnish telecommunications giant is best known for its phones, it’s also a major supplier of networking and transmission equipment to mobile operators. In the sub-sub-basement of the Nokia Research Center in Helsinki, Finland, where their equipment is quarantined from the clamor of cellular signals, researchers are building and testing a prototype beamforming base station antenna that could triple the capacity of the newest generation of cellular networks.
[Click here to view images of the antenna, its environs, and its keepers.]
Those new networks aren’t overloaded yet. But that’s no cause for complacency. “The 3G systems, such as wideband CDMA, are just beginning to be deployed around the world, so the networks are by no means congested at the moment,” says Hannu Kauppinen, senior research manager for radio technologies at Nokia Research Center. “But we anticipate that in the future, operators will have a need for capacity increases. That is why we are investigating this feature.”
Whereas a traditional cell-phone tower works like a lawn sprinkler, radiating in a circle, a beamforming antenna works like a hose. “The basic idea is that in a crowded area you want to give the maximum signal to the appropriate person, rather than wasting the energy by spreading it out over a broader volume,” explains Greg Hindman, president and cofounder of Torrance, CA-based Nearfield Systems, which builds testing and measurement systems for manufacturers of radio equipment. “A lot of our customers are working on this.”
New ways to support more callers are needed because cellular-phone networks employ a finite resource: the radio spectrum. The original technique for serving multiple wireless users in a populated space, pioneered more than 40 years ago, was to divide the space into cells, each served by a separate base station. But since cells were large and might contain many customers, that wasn’t enough. Signals had to be divided up using different radio frequencies, or channels.