Today’s mobile users demand faster data speeds and more reliable service. 5G, the next generation of wireless networks, promises to deliver that and much more. With 5G, users will be able to download high-definition movies in under a second (which is10 min It will also be available over 4G LTE, and wireless engineers say these networks will spur development of other new technologies as well. Self-driving cars, Virtual reality,and Internet of Things.
If all goes well, the telecom company hopes to debut the first commercial 5G networks.Early 2020sBut now 5G 5G is still in the planning stages, with companies and industry groups collaborating to hammer out specifics, but all agree: as the number of mobile users and data demands grow, 5G will need to handle much more traffic, much faster, than the base stations that make up today’s cellular networks.
To achieve this, wireless engineers are designing a series of new technologies that, combined,Less than 1ms latency (compared to Approximately 70 milliseconds On today’s 4G networks, peak download speeds are 20Gbit/s (compared to 1Gb/s for 4G) to the user.
At this point, it’s still unclear which technologies will be most useful for 5G in the long term, but some early front-runners have emerged: mmWave, small cells, massive MIMO, full duplex, and beamforming. To understand how 5G will differ from current 4G networks, it’s helpful to look at each of these technologies in turn and what each means for wireless users.
Millimeter Wave
Today’s wireless networks are facing a problem: More people and devices are consuming more data than ever before, yet that data is being crammed into the same parts of the radio frequency spectrum that mobile providers have always used – meaning less bandwidth, slower service, and more dropped connections for everyone.
One way around this problem is to transmit signals in entirely new bands that have never been used for mobile service before. So providers Millimeter WaveIt uses higher frequencies than the radio waves that have been used for cell phones for many years.
Millimeter waves are30 and 300 GHzCompared to the sub-6GHz bands previously used by mobile devices, mmWave is a wider frequency band, called mmWave because its length ranges from 100 to 2000 nm.1 to 10 mmCompared to the radio waves used in today’s smartphones,Tens of centimeters length.
Until now, mmWave has only been used in practical applications by operators of satellite and radar systems. Now, some mobile phone providers are starting to use mmWave to transmit data between fixed points, such as two cell towers. But using mmWave to connect mobile users to nearby cell towers is an entirely new approach.
But mmWave has one big drawback: it doesn’t easily pass through buildings and obstacles and is absorbed by leaves and rain, which is why 5G networks will likely supplement traditional cell towers with another new technology called small cells.
Small Cell
Small Cells are portable, small base stations that require minimal power to operate and can be placed roughly every 250 meters throughout a city. To prevent signal drops, carriers could install thousands of these base stations in a city, forming a dense network that acts like a relay team, receiving signals from other base stations and transmitting data to users in any location.
Traditional cell networks also rely on an increasing number of base stations, but to deliver 5G performance, they will need a much larger infrastructure. Fortunately, transmitting small millimeter waves, small cell antennas can be much smaller than traditional antennas. This size difference makes it easier to stick cells on lampposts or the rooftops of buildings.
This fundamentally different network structure allows for better and more efficient use of spectrum. More stations means that frequencies used by one station to connect devices in one area can be reused by another station in another area to serve different customers. But there’s a problem: the sheer number of small cells needed to build a 5G network can make it difficult to build in rural areas.
In addition to broadcasting over millimeter waves, 5G base stations will also have far more antennas than current cellphone network base stations to take advantage of another new technology: Massive MIMO.
Massive MIMO
Today’s 4G base stations have 12 ports for antennas that handle all cellular traffic: eight for transmitting and four for receiving. But 5G base stations can support around 100 ports, allowing many more antennas to be installed in an array. This ability will allow base stations to send and receive signals from many users at once, increasing the capacity of mobile networks by 100 times.22 or above.
This technology Massive MIMOIt all starts with MIMO. MIMO stands for multiple input multiple output. MIMO describes a wireless system that uses two or more transmitters and receivers to send and receive large amounts of data at once. Massive MIMO takes this concept to a new level by arranging dozens of antennas in a single array.
MIMO has already been adopted in some 4G base stations. But so far, Massive MIMO has only been tested in laboratories and a few field trials. Early tests have shown that: Spectral efficiencyThis measures how many bits of data can be sent per second to a specific number of users.
Massive MIMO looks very promising for the future of 5G. But installing so many antennas to handle cellular traffic also increases interference when signals cross, which is why 5G stations need to incorporate beamforming.
Beamforming
Beamforming is a traffic signaling system in cell towers that identifies the most efficient data delivery route to a particular user, reducing interference to nearby users in the process. There are a few ways this can be implemented in 5G networks, depending on the situation and technology.
Beamforming helps massive MIMO arrays use the surrounding spectrum more efficiently. A key challenge with massive MIMO is transmitting more information at once from more antennas while reducing interference. At a massive MIMO base station, signal-processing algorithms plan the best transmission route in the air to each user. They then send individual data packets in different directions, bouncing them off buildings and other objects in precisely coordinated patterns. Beamforming coordinates the packet movement and arrival times, allowing the many users and antennas on a massive MIMO array to exchange more information at once.
For mmWave, beamforming is primarily used to address a different problem: Cell phone signals are easily blocked by objects and tend to be weak over long distances. In this case, beamforming can help by focusing the signal into a concentrated beam that points only in the direction of the user, rather than broadcasting it in many directions at once. This approach increases the chances that the signal will get there intact and reduces all other interference.
Radio engineers are working to achieve the high throughput and low latency needed for 5G through the increased data rates achieved by broadcasting in millimeter waves, the increased spectral efficiency achieved with Massive MIMO, and a technology called full-duplex, which changes how antennas send and receive data.
Full Duplex
Today’s base stations and cell phones rely on walkie-talkies that take turns operating when sending and receiving information on the same frequency, or on different frequencies when users are sending and receiving information at the same time.
5G allows transceivers to simultaneously transmit and receive data on the same frequency. This technology Full DuplexIt can double the capacity at the most basic physical layer of a wireless network. Imagine two people talking at the same time and still being able to understand each other, which means conversations take half the time and the next one can start sooner.
Some militaries already use full-duplex communication technology, which requires bulky equipment. Full Duplex on Personal DevicesResearchers need to design circuitry that can route incoming and outgoing signals so they don’t collide while the antennas are simultaneously transmitting and receiving data.
This is especially difficult because radio waves tend to travel both forward and backward at the same frequency, a principle called reciprocity. But recentlyExperts have built silicon transistors that act like high-speed switches, stopping these waves from rotating in opposite directions, allowing them to send and receive signals at the same frequency simultaneously.
One drawback of full-duplex communication is that it introduces even more signal interference from pesky echoes. When the transmitter emits a signal, it’s so close to the device’s antenna that it’s stronger than any signal it receives. Only special echo cancellation techniques allow the antenna to both talk and listen at the same time.
Engineers hope to use these and other 5G technologies to build the wireless networks that tomorrow’s smartphone users, VR gamers, and self-driving cars will rely on every day. Already, researchers and companies are excited about 5G, promising ultra-low latency and record-breaking data speeds for consumers. If they can solve the remaining challenges and figure out how to make all these systems work together, ultra-fast 5G service could be available to consumers within the next five years.
Writing credits:
- Amy Nordrum – Writer & Narrator
Production:
- Celia Gorman – Executive Producer
- Kristen Clarke – producer
Art direction and illustration:
- Brandon Palacios – Art Director
- Mike Spector – Illustrator
- Ove Edfors – Professional & Illustrator
Special Thanks: IEEE Spectrum would like to thank the following experts for their contributions to this video: Harish Krishnaswamy (Columbia University), Gabriel M. Rebeiz (UCSD), Ove Edfors (Lund University), Yonghui Li (University of Sydney), Paul Harris (University of Bristol), Andrew Nix (University of Bristol), and Mark Beach (University of Bristol).
