Shrinking Cells and Narrowing beams

Håkan Eriksson may be Ericsson’s technology visionary, but he’s a pragmatic visionary. He believes that the demands placed on future wireless networks will be awesome as more of our broadband lives move into the mobile world, but he also believes that there are definite foreseeable means of addressing those problems. The future wireless network will be incredibly complex, but it isn’t in the realm of science fiction.

Eriksson—no relation to Lars Magnus Ericsson, the company’s founder—said that after Long-Term Evolution (LTE) achieving higher degrees of spectral efficiency will become increasingly more difficult. There is only so much information that can be crammed into a hertz of spectrum before any gains are drowned out by signal noise. The trick, then, is not to make higher capacity to base stations but to deploy a lot more of them and deploy them a lot more effectively.

“As bit rates go up, you’ll have to reduce the space between antennas,” Eriksson said. “That means really, really small cells—small base stations covering small areas.”

In the year 2025, Eriksson predicts that there will be a base station-cell site on every city lamp post, shrinking cell radii down to dozens of meters. The overall capacity available to each device in a given area thus increases dramatically as someone moves betweens dozens of cells in the normal course of walking to the grocery store or hundreds while driving to work. But such an architecture also creates enormous demands on network management, Eriksson said.

“Think of the macro-diversity encountered when simply driving down the street,” Eriksson said. “You would be passing through a new cell at every lamp post. There has to be tremendous mobility in such a solution.” A network couldn’t just simply track a device with its current cell and neighboring cells, Eriksson said. The network would have to function like a chess player, anticipating handoffs four or five cells down the road. The network of the future won’t just be a high-capacity network but a highly intelligent one, Eriksson said.