If you want 5G, there’s a good chance you'll need a small cell nearby to deliver it. Putting up that cell may be hard because of a host of problems, but Nokia Bell Labs thinks it can solve some of them with drones and tiny solar panels.
Nokia's F-Cell is an experimental LTE small cell that doesn't need any wires. It gets power from solar panels on its surface and communicates with the carrier's core network over a high-speed wireless connection. No one even needs to climb up on a roof to install it: The company recently delivered an F-Cell to the roof of one of its buildings in Sunnyvale, California, using a drone.
F-Cells won’t start showing up everywhere tomorrow, but anything to speed up small-cell deployment could make a big difference when 5G starts going live in 2020. The next generation of cellular will probably require dense networks of small cells to deliver the gigabit speeds being promised, and carriers will face both legal and technical hurdles when they try to put them up.
Though 5G is expected to improve mobile services in several areas, including the internet of things, it will be the technology's eye-popping speeds of 5Gbps (bits per second) to 10Gbps that will call for small cells using millimeter-wave frequencies, said Tom Keathley, senior vice president of wireless network architecture and design at AT&T. They will be deployed first in dense urban areas, he said.
Most cells today are mounted on towers placed an average of two kilometers apart, according to AT&T. Carriers typically have to get clearance from local governments, pay rent and run fiber or copper cables from the towers to their wired networks.
In order to offer better performance to more subscribers, 5G networks are expected to use much higher frequencies that are harder to send over long distances. That will take smaller cells, spaced only about 250 meters apart, so all the headaches of deploying a cell will be repeated many more times.
There are about 200,000 cells in the U.S. now, but there may be millions in the coming 5G era, Federal Communications Commission Chairman Tom Wheeler warned last month. Neighborhoods that block small cells because of health or aesthetic concerns could miss out on 5G, he said. The FCC is now working to streamline cell site approvals.
The F-Cell is designed to solve the technical challenges. It doesn't need a power cord because it’s powered by the sun, and it doesn't need a cable because it connects to the wired network through a central wireless hub that can serve several F-Cells.
In Nokia’s demonstration, a drone carried an F-Cell to the roof of the building and dropped it off, leaving the cell to turn itself on, configure itself and automatically connect to the wireless backhaul network.
That network is built around a closed-loop, 64-antenna system that uses massive MIMO (multiple in, multiple out) technology. It forms eight radio beams to communicate with eight F-Cells.
Each cell has a total system throughput of about 1Gbps, and with enhancements and higher frequencies, that could grow to tens of gigabits per second, Nokia says.
A "drop and forget" cell like the F-Cell would make small-cell deployments simpler and cheaper, said Tolaga Research analyst Phil Marshall. But it wouldn’t help with issues like zoning and negotiations with landlords, which are already big challenges, he said.
AT&T is already making deals with municipalities to mount LTE small cells on light poles and other sites, Keathley said. One such deal can give the carrier access to small-cell locations throughout a city, and by the time 5G is available, AT&T will have laid much of the groundwork for that next deployment, he said.
Marshall doesn't think current methods for getting small cells into cities will suffice for 5G. Carriers need new approaches, like sharing sites with rival operators, offering free Wi-Fi from the sites or using them to help cities deliver services, he said. "5G will need a heap of sites."