What 5G Will Be: Crazy-Fast Wireless Tested in New York City
The world’s biggest cell-phone maker, Samsung, caused a stir last week by announcing an ultrafast wireless technology that it unofficially dubbed “5G.” And the technology has, in fact, been tested on the streets of New York.
The system is impressive but is still in development—which is true of all the technologies that will underpin the next generation of wireless communications. When 5G does arrive, it will likely combine new wireless protocols with new network designs, spectrum-sharing schemes, and more small transmitters.
Samsung says its new transceiver can send and receive data at speeds of more than a gigabit per second over up to two kilometers—and it could deliver tens of gigabits per second at shorter distances. This compares to about 75 megabits per second for the latest standard, known as 4G LTE. The Samsung technology relies on 28-gigahertz frequencies, which can carry commensurately more data but can be blocked by buildings, people, foliage, and even rainfall.
Samsung says it has greatly mitigated these problems by sending data over any of 64 antennas, dynamically shaping how the signal is divided up, and even controlling the direction in which it is sent, making changes in tens of nanoseconds in response to changing conditions (among other features, it can catch stray reflections of signals that had bounced off an obstruction). The company did not grant an interview request, but the technology is described in this 2010 patent filing.
The work has also been tested in the real world. Last summer, an academic lab, NYU Wireless, part of the Polytechnic Institute of New York University, did performance tests for Samsung in New York City and Austin, Texas, and found that the technology, which is also known as millimeter-wave cellular, could work well even 200 meters away from the transmitter, and even in a cluttered environment. “A lot of people have the same reaction: ‘How can it work?’ But we showed that it can be done,” says Theodore Rappaport, director of NYU Wireless. “Our measurements have helped give Samsung and the rest of the wireless industry confidence that (28-gigahertz) wireless is viable.”
Still, the ranges involved suggest that high-frequency technologies will be best for short-range hot spots, says Jeff Reed, director of the wireless research center at Virginia Tech. “I am skeptical that they will be able to deliver high data rates with the mobility that we have become accustomed to with 2G, 3G, and 4G cellular systems,” he says. “Meanwhile, we still have plenty of room to improve 4G systems that operate at more favorable lower frequency ranges.”
It’s certainly true that so far, the industry has only implemented the most basic features of 4G LTE. More sophisticated features will allow improvements in data rates. One of them is “carrier aggregation,” or the ability to use multiple frequencies at the same time to send a signal. Another is the use of multiple antennas, in ways akin to Samsung’s technology. Finally, various signal-processing tricks can effectively boost bandwidth by intelligently coördinating the efforts of base stations and devices on the networks to avoid interference.
Beyond these enhancements, greater used of unlicensed spectrum—such as that used by Wi-Fi equipment—can offload traffic inside buildings to provide a huge boost; after all, some 70 percent of mobile traffic comes from people inside homes and offices.
Expanding this concept are so-called small cells—cellular transmitters that pick up a signal from a few tens of yards and relay it over the wired Internet (see “Tiny Transmitters Could Help Avert Data Throttling”). If there were one of these in every home, they could provide an entire neighborhood or urban network with cellular coverage without requiring any large base station (see “Qualcomm Proposes a Cell-Phone Network by the People, for the People”).
The everyday reality for consumers is that in many cases, high-speed data is better when it’s coming from Wi-Fi hot spots, not 3G and 4G networks, whose peak speeds are not always available everywhere or at all times of the day. “This begs the question: Are faster cellular data speeds really what we need, or would we be better served if 5G improved what cellular standards do better than Wi-Fi, which is wide area mobility and seamless connectivity?” says Vanu Bose, CEO of Vanu, a wireless company in Cambridge, Massachusetts. “Despite the high data speeds on 3G and 4G networks, we all still suffer from dropped calls and poor coverage in many places.”
One technology that could provide better coverage by hopping between different frequencies and different wireless protocols is known as cognitive radio. On a second-by-second basis, such a radio would detect and exploit available spectrum holes. “In the mid term, this is a more likely solution for high data rates and mobility than using higher frequencies,” Reed says (see “The Spectrum Crunch That Wasn’t” and “4G on the Baby-Monitor Frequency”).
While Samsung’s technology may form part of the 5G future—an ultrafast network technology running in hot spots—a larger mix of technologies and strategies will be needed to deliver data more quickly and reliably. Standards are set by the International Telecommunications Union, a United Nations body. It will be several years until even all of the 4G LTE versions are rolled out. Samsung said its technology could be ready by 2020.
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