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5G – A Few Frequency Facts

Delivering on the promise of “wireless fiber” first requires solving a few challenges.

a few frequency facts image
Cradlepoint

Bigger swaths of spectrum are crucial to accommodate the massive increase in data usage produced by people and devices consuming more data than ever. For 5G to power these devices and sensors in the near future, it will need a lot more breathing room on the airwaves to acquire the bandwidth needed; refer to my previous blog 5G – Better Broadband Bandwidth.  

Wireless spectrum is the oxygen that keeps the network alive, and more spectrum will allow 5G to deliver its full potential. 

While 5G will be much more efficient than prior network technologies, history and physics pose several challenges that need to be worked around or through in order to deliver on the promise of “wireless fiber.” This blog explores a few frequency facts surrounding the next generation of wireless connectivity. 

Fact 1: There are advantages and disadvantages of using different frequencies

One of the most fundamental laws of physics, as it relates to wireless, is that lower frequencies travel farther and penetrate buildings deeper (or propagate better) than higher frequencies.

600 MHz

In the U.S., the FCC recently auctioned off bands in the 600 MHz range. This is a lower frequency, so it can easily pass through physical objects and travel many miles.  

5 GHz

5 GHz, an unlicensed range commonly used for WiFi (and since it’s unlicensed, anything else anyone wants to broadcast in that range such as Bluetooth Low Energy), is more likely to be absorbed by solid objects, but there is much more bandwidth (roughly 500 MHz in total) available for use; albeit shared. It also doesn’t propagate very well, so it is generally used for short ranges. That’s one reason why multiple WiFi access points are required to cover even small buildings.

It’s simple math, really – if you want, say, 800 MHz to deliver fiber-like speeds and also wanted that at a low frequency like 600 MHz, you’d take up from 600 MHz to 1.4 GHz (1400 MHz). 

Fact 2: The airwaves are jam-packed

The first commercial use of radio waves was for…well, radios. Remember those? Listening to music, news and more on AM and FM frequencies? Then came television – VHF and UHF. In the old days, the technologies used were analog in nature, thus quite inefficient and required wide bands for each channel. And once mass adoption of those frequencies exists, it’s difficult to reassign them for another use. So, when new technologies came along like cellular, they were assigned higher frequencies.

Over time, more and more frequency bands got licensed, generally from lower to higher, and frankly, there’s not much left in the best-propagating frequencies. Using the example above, between 600 MHz and 1.4 GHz, there are dozens of licensed bands with dozens of applications (mostly cellular), that aren’t available for use.

Fact 3: High-frequency millimeter waves will greatly increase wireless capacity and speeds for future 5G networks

The good news is that high-band millimeter wave spectrum is available for use, so wide bands can be assigned. Millimeter wave spectrum is generally considered the band of spectrum between 6 GHz and 100 GHz, with 5G trials being conducted in a variety of bands within this range. The bad news is that these frequencies get absorbed very easily by simple objects like leaves and even rain. But where there’s a will, there’s a way and smart radio frequency engineers will figure this one out. It might mean that millimeter waves could only be used in the urban core where lots of small cells can be built cost-effectively, but these frequencies will play an important role in delivering the high throughput that 5G promises.

Currently, millimeter wave is being used to transfer data from one fixed point to another (remember, higher frequencies makes it harder to penetrate buildings). Soon, millimeter wave will be combined with sub-6 GHz spectrum—including current LTE and WiFi to deliver ubiquitous coverage indoors and out. Also, CBRS (Citizens Broadband Radio Service) frequencies will be available, allowing for increased bandwidth on shared spectrum.

Fact 4: Frequency is available, creating the runway for 5G technologies 

In the U.S., the FCC recently made the CBRS frequency airwaves available. CBRS operates at 3.5 GHz using LTE to provide wireless networking. It’s 150 MHz wide and it can transmit a ton of data. Elsewhere in the world, regulators are making similar frequencies in this general range available as well. There’s still a lot of discussion in the industry about how these bands will be used, which technologies they will be used for (LTE vs. 5G), where (in-building vs. wide area) and whether they can be harmonized (consistent from country to county for roaming purposes), but 3.5 GHz will be another important resource to deliver the promise.

Fact 5: Future mobile networks will demand more spectrum in higher frequency ranges

At the end of the day, more spectrum is needed for the development of the new 5G ecosystem and the growing traffic capacity demands.  With higher frequency ranges comes bigger bandwidth – and while the engineering challenges are daunting, it’ll get figured out. Remember, where there’s a will, there’s a way.

Watch for our next blog in our 5G series, “5G Connection Density – Massive IoT and So Much More”.

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