Many of today’s telecommunications companies are working to bring faster Internet connections to urban and other high-density areas by using smaller cells with ranges of 10 to 100 meters. But those service providers aren’t doing much to provide access for the 3 billion people who live in rural areas hundreds of kilometers from a base station.
IEEE Fellow Gerhard Fettweis, cochair of the IEEE 5G Initiative, says connecting those in sparsely populated areas can be done by increasing the range of telecommunication cells and massive multiple-input multiple-output (MIMO) antenna systems installed at both the transmitter and receiver.
“While areas in Africa, Asia, northern Europe, and North and South America can receive a signal 100 kilometers away from a base station, the data rate transmission speed is only in the range of 10 kilobits per second, just enough to make a voice call or send a text message,” Fettweis says. “Our hope with 5G is that cells within a radius of 100 kilometers will achieve at least 100 megabits per second.”
To provide faster speeds to people in remote areas, the transmit power could be increased, he says. That’s where massive MIMO antenna systems located at the transmitter and receiver will help in 5G, he says, adding that distributed antenna systems connected via optical fibers will help boost the reliability of 5G connections.
Current cell towers typically point their antennas in three directions. Cut the circle into three parts, Fettweis says, and the energy in this one sector could be transmitted no matter how far away a cellphone is. It could receive calls any place in this sector because only one dedicated antenna is needed to receive the signal.
“This is one of the big technology jumps happening with 5G,” Fettweis says. “Instead of speeds of 10 kb/s or 100 kb/s at a 100-kilometer radius, 100 Mb/s will possible.”
“What we’ll be able to do with massive MIMO is build antenna channels with 100, 200, or 500 elements,” he says. “If multiple antenna elements can be put together in a narrow beam, we could focus the energy exactly in the direction it’s needed. This means that today’s current antennas, which transmit the energy in a 120-degree pizza part of a cell, will focus their beam within less than 10 degrees.
CHEAPER AND FOCUSED
Companies attempting to provide Internet access to rural areas include Facebook (with Aquila solar-powered drones) and Google (with Project Loon balloons)—both still in the test phase. Fettweis says he believes a massive MIMO–powered 5G terrestrial system will be less expensive to build and operate than either of those airborne-based systems. He points out that airborne systems in the 1990s—low-Earth orbiting satellites—ended up being costly mistakes. The companies that built and launched the billion-dollar Iridium and Teledesic satellites went bankrupt.
Fettweis says, “5G would outcompete anything sent up into the air. Our hope is that 100-kilometer radius cells will achieve at least 100 Mb/s before 2025. That speed will be tough for an airborne system to achieve.”