In the Works: Next-Generation Wireless

5G is expected to be deployed by 2020

7 July 2014
Photo: Getty Images

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Today’s wireless networks have a hard time keeping up with the demand by mobile devices for higher data rates, multimedia services support, and ever more bandwidth. And when data starts being generated by the millions, if not billions, of machines and devices that are expected to comprise the Internet of Things, the current generation of wireless systems will be challenged as never before.

That’s why the communications industry is working on a fifth-generation wireless system. Compared with today’s 4G and LTE networks, researchers say 5G will achieve 1,000 times the system capacity; 10 times the energy efficiency, data rate, and spectral efficiency; and 25 times the average mobile cell throughput. The aim is to offer seamless and universal communications between any people, anywhere, at any time by just about any wireless device. Standards for 5G are likely to be defined between 2016 and 2018, with 5G-ready products not expected until 2020.

The IEEE Communications Society is helping to educate the communications industry and others with technical and research articles and meetings on the 5G world. The February issue of IEEE Communications Magazine, for example, published a special report that covered the prospects and challenges surrounding 5G, and the May issue of IEEE ComSoc Technology News (CTN) had articles on the topic recently published by the society, including a look at how fast 5G is likely to be.

In April, the IEEE Communications Society partnered with the Brooklyn 5G Summit—organized by NYU Wireless of the NYU Polytechnic School of Engineering and Nokia Solutions and Networks (NSN)—to record and stream the two-day event via IEEE.tv. The Brooklyn 5G Summit brought together thought leaders from industry, government, and academia who are preparing to set the stage for 5G wireless services.

The co-chairs were IEEE Senior Member Amitabha Ghosh and IEEE Fellow Ted Rappaport. Ghosh is head of NSN’s North America Radio Systems Technology and Innovation Office. Rappaport is the founder and director of NYU Wireless, the first academic research center combining wireless, computing, and medical applications.

In a keynote address, Hussein Moiin, NSN’s executive vice president of technology and innovation, declared, “We have the power to innovate a technology that will have a global reach and possibly have an impact on everyone. Our power comes from our collaboration.”

JUMPING HURDLES

Today’s wireless systems face serious hurdles if they’re to meet the demands of billions of data-hungry smartphones, tablets, and other devices. The number is already in the billions; mobile subscribers alone in the first quarter of this year totaled nearly 6.8 billion, according to the Ericsson Mobility Report. The systems that serve the devices were designed and developed in silos, resulting in limited ability to move seamlessly from one to the other—for example, from 3G and 4G cellular to Wi-Fi. The wireless systems also have spotty in-building coverage, consume a lot of power, and face a scarcity of radio frequency spectrum, according to “Cellular Architecture and Key Technologies for 5G Wireless Communication Networks,” an article in CTN.

Technologies that researchers say look promising for 5G include massive multiple-input multiple-output (MIMO) antenna systems installed at both the transmitter and receiver; energy-efficient communications; cognitive radio networks; visible-light communications; and extremely small, mobile femtocells, known as MFemtocells, that would be ideal for commuters.

In part, these technologies will tackle the problem of the relatively poor wireless service that exists inside buildings. Wireless devices are used indoors about 80 percent of the time, according to researchers, yet today’s cellular architecture relies only on outdoor base stations. That means signals transmitted indoors must penetrate building walls—which can result in dropped calls and slower transmission rates. The researchers propose using distributed antenna systems and MIMOs on outdoor base stations that would be distributed around a cell and connected via optical fibers. Antenna arrays also would be installed outside every large building to communicate with the outdoor base stations while they are joined by cables to the wireless access points inside the building. More antennas at both the transmitter and receiver could accommodate more data.

Such indoor connections could help wireless systems become more energy-efficient, researchers say, because by separating indoor traffic from outdoor traffic, the base station would face less pressure in allocating radio spectrum and so could transmit with less power.

Cognitive radio networks are viewed as a key solution to ease congestion in the RF spectrum. CR networks allow a secondary system to share spectrum bands with licensed primary systems, either on an interference-free basis or on an interference-tolerant basis, researchers say. The interference-free arrangement lets CR users borrow spectrum only when licensed users are not using it. In interference-tolerant CR networks, users share the spectrum with the licensee but keep the interference below a set threshold.

Another solution to help lessen the RF spectrum bottleneck is visible-light communications providing broadband wireless data connectivity. This can be accomplished with off-the-shelf white LEDs as signal transmitters and off-the-shelf p-intrinsic-n photodiodes or avalanche photodiodes as signal receivers. Data rates of 3.5 gigabytes per second have been reported from a single LED.

For wireless users moving about in cars, trains, and buses, MFemtocells can improve service quality. A moving network relying on femtocell technology can dynamically change interconnections as devices move around. Because MFemtocells can hand over signals on behalf of all their users, they are ideal for commuters.

The authors of "Networks and Devices for the 5G Era" say the cost and flexibility of 5G deployment will require a shift toward software-based implementations and virtualization of some network resources. In particular, the researchers say that 5G systems will have to create multiple virtual core networks tailored to the requirements of particular applications. For example, a system could feature a virtual core network to support machine-to-machine communications for smart appliances, a separate network to support Internet content, and still another to support media services such as video, gaming, and interactive cloud-based applications. Each could be configured by dynamically using resources from the same or different networks, according to the researchers.

BOOSTING BANDS

The authors of “5G Network Capacity: Key Elements and Technologies” predict a 1,000-fold increase in mobile traffic over the next decade. They say the increase could be handled by heterogeneous networks (HetNets), which use different types of network nodes equipped to handle various transmission power levels and data processing capabilities, and support different radio access technologies. In turn, these technologies are supported by different types of backhaul links.

The HetNets will support device-to-device (D2D) communications, which will allow devices close to each other—for example, in shopping malls, train stations, and stadiums—to communicate without going through the main network infrastructure, leading to higher efficiency, the authors say.

“D2D communication is very effective for traffic offloading and for improving spectrum reuse in densely populated deployment scenarios, which are the most challenging communications scenarios due to the spectrum constraints they impose,” the authors write.

A video of the papers and discussions presented at the Brooklyn 5G summit is available for purchase on demand.

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