The Massive MIMO antennas expected to be at the heart of so-called 5G next-gen mobile networks will come with some major challenges because of their huge size, according to Tod Sizer, head of access technologies research at Bell Labs , part of the Alcatel-Lucent (NYSE: ALU) empire. (See AlcaLu Breathes New Life Into Bell Labs and Prepare for a 5G Onslaught.)
He says operators will face a creative challenge in deploying 5G basestations in downtown areas.
"They're very flat, they're very large, and they'll never go on top of the big towers because there's too much wind blowing," Sizer said. "But you can hide them in the facades, say, right behind advertising billboards or on the side of walls or buildings."
Of course, even before they are deployed, there's no shortage of technical hurdles to be overcome to build antennas of that power and complexity.
No more than six MIMO (multiple input, multiple output) antennas are deployed in a 4G basestation, but 5G MIMO will likely involve hundreds, Sizer predicts.
"If you want to make 100 antennas work together, you need to get the costs to the point and the size and the weight and the power to be low enough so it's economic to deploy. The challenges we have in the digital processing are as severe as the heat and size issues."
Sizer said Massive MIMO would be likely deployed only in high-density urban areas. He describes it as "a wonderful technology for Singapore," where most people live in a high-rise, but wouldn't be required for medium-density suburbs.
He said that whereas 4G was primarily about the radio, the big challenge for 5G would be to create a user- or application-aware network with a focus on end-to-end performance.
"We know what the application is, we know what the network is. How can the network adapt to that particular woman, with that particular application, in that particular place?"
As well as the obvious issues of bandwidth and latency, 5G would also have to provide "responsivity," which Sizer describes as the ability to create a session, complete the operation quickly, and shut it down.
"For an app like search, that's critical… if I can create a connection, use it and then shut down the connection, that allows me to use the network less. That has impacts on the capacity of the network; it also impacts battery life."
He says the industry will need to get creative to acquire the spectrum resources necessary for 5G, such as millimeter waves or the use of LTE unlicensed spectrum through carrier aggregation.
He also points to under-used 5GHz bands used for radar surveillance near airports. "We're working with the federal government and the FCC to share that spectrum. If you're not within 100 kilometers of an airport, why can't I use it? Or use it when the radar is pointed in other directions?" asks the Bell Labs man.
Keep up to date with 5G views and developments at Light Reading's dedicated 5G track.
— Robert Clark, contributing editor, special to Light Reading