The top 5 5G wireless technologies

-January 03, 2018

Two of the top five most important wireless technologies for 5G networks for 2018 are the same ones that have always been of paramount importance for 5G networks: MIMO and beamforming.

MIMO and beamforming

With LTE/4G, the industry is nearing theoretical limits of time and frequency utilization. The next step in wireless, with 5G, is exploiting the spatial dimension, using any given frequency simultaneously as often as possible by emitting rigorously focused signals in different directions. The industry has challenges yet to surmount in adapting both technologies for 5G. There have been advances and variations on the themes in 2017, and 2018 is likely to see more of each.

5G will rely on arrays of antennas to provide a massive number of inputs and a massive number of outputs -- or MIMO. Beamforming will steer signals to specific devices. Source: T-Mobile

MIMO describes aggregating increasing numbers of antennas in ever-denser arrays on both the transmitting and receiving ends to create more data stream layers. Beamforming and the tightly associated technology of beam tracking, meanwhile, are about steering every signal on the best path to the receiver while avoiding signal interference. Beamforming will make MIMO more efficient.
Both technologies require further refinements for application to 5G network systems.

It remains difficult to physically shrink antennas; MIMO arrays for 5G are simply big (which is one of the reasons why practical 5G smartphones are unlikely before 2020 and perhaps even later). Most extant arrays still draw too much power to be fully practical.

Complicating the task of beamforming, signals will have to be steered along both altitude and azimuth. Source: Qorvo

Beamforming is what it says it is, but the term fails to imply the complexity involved. In 4G, transmitters triangulate on the receiver. The same will pertain in 5G, but in 5G the transmitter will also be able to map the physical environment and then calculate not only multipath bounce, but how to stagger the signal stream to take advantage of multipath in such a way as to avoid interference of simultaneous signals. The task increases in difficulty when either or both the transmitter and receiver are mobile.

All of this is complicated by additional technical challenges inherent in the next important aspect of 5G wireless.

Millimeter wave (mmWave)

The frequencies originally allocated for 5G maxed out at 6 GHz. Much of the spectrum most recently allocated for 5G services by various jurisdictions around the world are at various millimeter-wave frequencies.

The mmWave range is 30 GHz to 300 GHz. New 5G allocations around the world range from the upper-20s (26 GHz and 28 GHz, for example; technically not mmWave but often lumped into the category), several bands in the 30s, and a few more in the 40s. There is a Wi-Fi band at 60 GHz that may be used for 5G wireless. Others at higher frequencies are under consideration.

Spectrum near and squarely in the millimeter wave range (30 GHz to 300 GHz) is particularly suitable for increased data rates, making it interesting despite drawbacks. Source: Ericsson

On one hand, signals at these higher frequencies will support the significantly higher data rates specified for 5G. The industry still has work to do to improve the spectral efficiency that it has managed to achieve thus far.

On the other hand, propagation rates of mmWave signals are significantly less than desired. The mmWave signals don’t reach as far and don’t penetrate obstacles as well as sub-6 GHz signals.

Generally speaking, much of the componentry for 5G is still expensive; that is especially so in the mmWave spectrum. Costs will certainly drop with further integration, through economies of scale, and possibly based on future innovations.

In previous wireless network evolutions, there was essentially one target task: getting data to phones. Yes, that started with simple telephony and evolved to add broadband access and, yes, other types of devices are supported by 4G/LTE networks, but the vast majority of wireless network usage is delivering bits to and from mobile phones. That’s going to change with 5G. It is going to be an enabler of many IoT applications, but equally importantly, those IoT applications will help justify the evolution to 5G. Use cases, including the IoT, are literally built-in to the 5G technology roadmap, intrinsic to the development of the 5G market.

While many IoT devices will connect directly to 5G, others won’t. Many IoT applications will rely on vast numbers of simple, cheap sensors or other relatively simple devices. These devices might need to be low power or exceedingly low power; they might or might not require low-latency; they might or might not need to communicate with each other; the amount of data they generate (and perhaps receive) might vary wildly in size from device to device; they might need to be polled constantly in real time or only once every day, week, or even month. 5G connectivity will be not only technological overkill in many of these applications, but so expensive as to make many of them economically infeasible.

That’s why it will be extremely useful for the 5G market to also the next item.

Lower power wide area network (LP-WAN)

In many IoT applications, arrays of devices would connect via some wireless technology designed specifically for LP-WANs to a base station that would in turn connect with a high-speed, high bandwidth network. That network could be 5G, but it doesn’t have to be; 4G connectivity will sometimes be adequate – sometimes 3G will do. It’s also possible that if there is wireline access nearby, that might be as useful, if not more desirable; it’s just that there are a lot of places where wires aren’t anywhere nearby, and that favors connectivity to 5G networks.

There are several LP-WAN options out there. They include LoRaWAN, Sigfox, Weightless, NarrowBand-IoT, LTE M, Ingenu, and Symphony Link. The next version of Wi-Fi, 802.11ax, has a low-power option in the specification and might yet sneak into the mix.

Some of the LP-WAN options are proprietary and some the result of more inclusive development processes. They have varying levels of openness. It is too early to determine which will become popular, but this is certain: there are more LP-WAN wireless options than the market could possibly sustain on a long-term basis.

Mesh networking

In some IoT applications, it will be useful to have a wireless transmission technology appropriate not only for connecting vast numbers of simple, cheap devices, but also for interconnecting them. This is where mesh networking comes in. Some of the LP-WAN options didn’t start out with support for mesh networking, but almost all of them have it now.

Mesh is hardly unique to LP-WANs. It’s already being built into wireless LAN technologies. Zigbee and Thread started out as mesh technologies, Bluetooth has added it, and the next version of Wi-Fi will have it. This next version is called 802.11ax, aka Max. (Look at “11ax.” Now flop that first 1 so it’s facing the other way. See it?).

Wireless mesh could certainly be useful in 5G. Mesh networking isn’t particularly easy to do well in LANs in which all connected devices are stationary; taking into account mobile devices (people on the go, drones, cars) and the difficulty gets exacerbated. The industry is beginning to work on getting 5G to support mesh networking.

Mesh networks will help devices connect with each other. One possible use would be vehicle-to-vehicle (V2V) communication. Source: Michigan Technological University

Brian Santo has been writing about science and technology for over 30 years, covering cable networks, broadband, wireless, the Internet of things, T&M, semiconductors, consumer electronics, and more.

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