Understanding how 5G works: Sub-6 vs. mmWave networks

Understanding how 5G works: Sub-6 vs. mmWave networks

There’s no denying that 5G technology is one of the hottest topics right now, and as we all begin to use it in our daily lives, we’re all naturally curious about how it works. 5G improves on 4G, but there is a lot of nuance involved in how you connect to the network. In the case of 5G, the technology is divided into two distinct parts: Sub-6 and mmWave.

When your phone connects to “5G,” it could be to either type of 5G network coverage. However, which one you connect to can have a significant impact on your 5G experience. Here are the fundamentals you need to know to understand the distinction between Sub-6 5G and mmWave 5G.

What exactly is Sub-6 5G?

The distinction between Sub-6 and mmWave is straightforward: Take a look at the radio spectrum that is being used for the network. Sub-6 5G operates at frequencies less than 6GHz, which is self-explanatory. This is significant for several reasons: This is where 4G, 3G, and 2G networks have historically operated, and this is where 5G will most likely operate in the next five years.

Because Sub-6 5G requires nothing more than tower upgrades, the best 5G carriers have been able to quickly deploy “nationwide” networks using their existing towers and spectrum. Simply by making 5G-specific changes to the towers, they can begin serving 5G alongside 4G across the majority of the country. Furthermore, because carriers already have significant spectrum holdings in these lower frequencies, they can provide relatively high output with 5G without jeopardizing their 4G offerings.

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All of this means that for the next few years, the majority of the time you’ll be using 5G, it’ll be Sub-6. And, unfortunately, for the foreseeable future, that Sub-6 5G won’t be noticeably better than the 4G you’re used to.

The issue is that Sub-6 networks do not provide a noticeably better experience than the most recent 4G networks. That makes sense — it’s 5G, but it’s still subject to many of the same constraints as 4G networks before it. Sub-6 5G networks are only slightly faster and have slightly lower latency than 4G networks.

The only significant improvement in experience found with Sub-6 is in the so-called “midband” frequencies, between 2GHz and 6GHz, where 4G networks have traditionally not operated but 5G can. With a large amount of unused spectrum, no competition from existing 4G networks, and some new network technology, midband 5G can be a great “Goldilocks” network that balances higher speeds with reasonable range and object avoidance. Midband will be an important part of every carrier’s overall 5G strategy, as T-“layer Mobile’s cake” approach has repeatedly demonstrated.

What is mmWave 5G?

Then there’s mmWave (millimeter wave), which operates at much higher frequencies, ranging from 30GHz to 300GHz. Carriers are currently operating between 30GHz and 40GHz, but new spectrum up to 48GHz has recently been released through government auctions. Beyond that, the 60GHz range is actually unregulated spectrum, and frequencies above 70GHz are frequently used for very specific point-to-point fixed wireless networks.

But, returning to mmWave 5G on your phone: This is a completely new network with no ties to existing 4G networks or infrastructure. That is, it has enormous potential but will take significantly longer to deploy than Sub-6 networks.

mmWave 5G networks can provide tremendous data speeds and ultralow latency by utilizing previously unused spectrum. mmWave is the technology behind 3Gbps download speeds, 1-millisecond latency, and futuristic real-time communications between devices, cars, and medical equipment.

mmWave networks have been launched by Verizon, AT&T, and T-Mobile, but deployment is slow. Because mmWave frequencies are so high, they cause significant coverage issues. The shorter the radio waves can travel, the higher the frequency. That means you’re going to need a lot of towers. And calling them “towers” is a bit misleading; unlike traditional cell towers, these are so-called “small cells” that are hyperlocalized to provide service to an area as small as one city street in one direction.

This is necessary due to the short range of mmWave, as well as the fact that any type of obstacle can have a significant impact on its performance. An mmWave signal can be disrupted by structures such as buildings, cars, trees, and even windows. So, in order to provide anything resembling coverage, hundreds of thousands of small mmWave cell sites must be strewn about the streets. Simply put, mmWave is not forgiving in this case. Every carrier is confronted with this reality.

Because of these technical challenges, mmWave rollouts are extremely slow. While mmWave 5G is available in some cities, it is extremely inconsistent — even the direction you face can affect whether you receive a signal. When you do get a signal, however, the speeds are absolutely mind-boggling: up to 3Gbps download speeds with single-digit millisecond latency. Furthermore, mmWave has enormous capacity potential, which means that more devices can be connected to a single network at the same time without degrading service. No matter how you look at it, that is completely game-changing.

Verizon and AT&T have both decided to separate their mmWave networks from their Sub-6 5G networks. Verizon offers 5G UWB (Ultra Wideband), while AT&T offers 5G+. This is mostly perplexing, but it does help you determine whether your phone is connected to Sub-6 or mmWave 5G.

Soon, you’ll be using both Sub-6 and mmWave.

Sub-6 is the 5G of today, while mmWave is unquestionably the 5G of the future. However, it is not quite that simple. It’s obvious that we’ll need to use both Sub-6 and mmWave at some point. Both are good at different things — Sub-6 for consistency and coverage, and mmWave for speed and density — and can be used in tandem. Carriers can leverage their strengths and provide a better overall experience by utilizing both.

The goal is for your phone or another device to always be connected to a 5G network and to be able to seamlessly switch between Sub-6 and mmWave without you even realizing it. It will arrive sooner than you think.

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