As mobile researchers and networking companies kick around potential 5G technologies in their labs, the Federal Communications Commission is taking its own regulatory whack at the ball. In a recent blog post, FCC Chairman Tom Wheeler wrote that he’s asking his fellow commissioners to begin investigating frequencies in the 24 GHz and higher bands for possible 5G use.
These frequencies, often referred to as millimeter waves, reside high above the portion of the electromagnetic spectrum used for mobile communications (which today stretches from 700 MHz to 2.7 GHz). There’s a lot of spectrum up there for the taking, but the problem is range. At the lower power levels needed for mobile communications, those waves just don’t propagate that far.
Typically millimeter waves are used for backhaul, connecting towers and buildings with high-powered point-to-point links. There’s a lot of discussion today about using those frequencies in both today’s 4G and future 5G networks to link to together vast networks of small cells. Those tiny cells will layer enormous amounts of capacity into dense high-traffic zones of the network, and millimeter waves would act as the glue connecting them together and back to the network core.
But 5G researchers believe that these millimeter waves could be the final access link between tower and device, delivering wireless speeds unheard of today; in the 1 Gbps range or higher. The idea is to use massive antenna arrays and beam shaping techniques to send a boatload of parallel low-power signals to a receiver. Those low-power signals would reinforce one another, greatly increasing the distance they could travel while preserving their data fidelity.
We’re already seeing precursors of this technology used in 4G networks on current mobile spectrum. [company]T-Mobile US[/company] has put up four-antenna systems on its LTE towers, and [company]Sprint[/company] is installing eight-antenna rigs in its new Spark network. But big networking companies like [company]Nokia[/company] and [company]Samsung[/company] and startups like Bluwan are piling on many more multiples of antennas as they move up frequency charts. Last year, Samsung announced a lab trial of such massive MIMO technologies using 64 antennas and achieving 1 Gbps of throughput over a mile.
There’s still some skepticism among industry experts whether these technologies could ever truly connect a mobile device moving about the network, but that doesn’t preclude millimeter technologies being used for fixed wireless or portable device use cases. Also, millimeter wave access is just one of many technologies being proposed for a 5G standard. Researchers are exploring everything from super-dense networking – think several cells in every room – to devices that can connect to multiple networks and multiple signals simultaneously.
Either way, Wheeler doesn’t appear to be jumping to any premature conclusions. He’s asking the Commission to approve a notice of inquiry to learn more about the technologies at stake before making any decisions about spectrum policy changes.
Wheeler added that he’s also proposing rule changes that might make deploying 4G small cell networks easier. His draft order would make it easier for carriers to install these tiny base stations – which take up a fraction of the space as traditionally tower-mounted macro-cell – in urban zones, hanging from lamp posts or utility poles and mounted on the sides of buildings.