Enlarge /. Artistic impression from playing with 5G.
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5G caused a lot of buzz in the last year – a lot of it, unfortunately, not all that coherent. Today we're going to take a detailed, realistic look at how we can expect 5G to improve cellular broadband, focusing on the impact we can potentially expect on gaming. Surprise: the news is actually not bad!
What is 5G
Before we can talk about what to expect from 5G, we need to talk about what 5G actually is – and what isn't. 5G, short for "fifth generation", is the next cellular communication protocol. 5G is not specifically a given frequency or band. There are two main bands that 5G can operate on – millimeter waves and sub-6 GHz. The exact frequencies within these bands that your devices use differs from network operator to network operator and from country to country.
Enlarge /. Very close to a cell tower.
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The sub-6 GHz band is not new territory. The frequencies used there are the same as those used by network operators for 4G / LTE services. Sub-6 GHz can be further divided into low-band (below 1 GHz) and mid-band (2.5 GHz – 3.5 GHz). Low-band offers greater range from the tower, but at lower speeds. The middle band offers a higher speed, but a shorter range. It's worth noting that "shorter range" isn't exactly a curse – the greater the range from the tower, the more users will have the same finite airtime and the slower the speeds and the less predictable the latency you will see.
While we expect 5G to be significantly better than 4G in sub-6 GHz bands, the millimeter wave – between 24 GHz and 39 GHz in the US – mostly refers to the breathless 5G coverage you've seen in the past .
The amount of sheer bandwidth available to millimeter waves – or "mmWave" for short – is pretty insane. The specification allows individual channel widths of 800 MHz, at which we can expect edge data rates (the lower limit of the rates you would see from a reliable connection) of 400 Mbit / s.
However, throughput isn't usually the killer metric for gaming – latency is. We'll take a more skeptical look at this later, but mmWave is expected to deliver less than a millisecond OTA (over the air) latency.
A closer look at sub-6GHz 5G
At this point you may be wondering why anyone bothered with sub-6 GHz bands if they can't and can't offer similar bandwidth, throughput, and latency to mmWave. While mmWave can certainly outperform low- or mid-band connections, it does have some pretty serious drawbacks. In short, the higher the frequency of a given band, the less it is able to penetrate obstacles.
Enlarge /. From one of our earlier pieces where we talk about how higher frequency signals are more affected by walls and other obstacles.
At less than 1 GHz, the low-band version below 6 GHz is hardly affected by most obstacles. Typically, you need something on the order of a mountain between your device and the tower to significantly affect the quality of the connection. But you also have very little bandwidth to work, which severely limits the top speed. Nowadays you might see 100Mbps or even 200Mbps from a 5G low-band connection – but those numbers will almost certainly drop sharply as 5G adoption grows.
The mid-band (2.5 GHz to 3.5 GHz) is a good compromise for urban areas. It doesn't penetrate walls and similar obstacles as well as the low band, but that's as much a blessing as a curse – a lower penetration makes it easier for large numbers of towers in a device density of a few square kilometers to work with one another without disturbing a lot . Midband 5G is a slightly higher frequency than modern 4G, whose higher band usually runs either just below or just above 2.4 GHz Wi-Fi.
Mid-band channels are wider than low-band channels and have proportionally higher speeds – from 125 Mbit / s at the low end to 500 Mbit / s or higher under more ideal circumstances.
A realistic look at mmWave
This brings us back to the millimeter wave – the Shangri-La with 800 MHz channel width, latency of less than a millisecond, and free puppies for everyone. At least that's how much 5G marketing sounded like.
The problem is, mmWave frequencies are absolutely terrible when penetrating obstacles. We spoke extensively with Qualcomm's engineers who confirmed what we already know about 30GHz-40GHz RF – it won't go straight into buildings. Still, mmWave is far more useful than you might think based on that one fact alone.
Enlarge /. Common frequencies used by consumer-facing wireless devices. Take a look at the whole mmWave spectrum!
Although mmWave frequencies do not penetrate directly into exterior walls, they bounce off hard surfaces well – and the resulting multipath propagation with high frequency is absolutely usable. In September 2019, a reporter for PC Magazine demonstrated that on the wrong side of an elevator shaft, more than 400 Mbit / s was achieved by a 5G panel and more than 1 Gbit / s was achieved on the other side of an interior wall.
The usefulness of RF multipath propagation – "echoes" reflecting off hard surfaces such as concrete buildings and sidewalks – makes mmWave a pretty reasonable proposition for outdoor users. The range is still quite low compared to mid-band frequencies, but this is as much a blessing as a curse (again). A shorter range means that you need more towers, but also comparatively fewer users per tower, less interference from fewer other users in "earshot" and thus effectively more airtime per user.
The expected widespread availability of mmWave to external users will have a major impact on the quality of the mid-band available to internal users. (Remember, there is only so much airtime available.) If you can split your load across non-overlapping spectra by serving external users at mmWave and internal users at mid-band sub-6 GHz, whatever airtime available will be used sharp up.