It already is tough to determine what “5G speed” actually means, as early 5G often is based as much on 4G as 5G.
And the problem of assessing 5G speed is going to get worse. We will have to compare 5G primarily using low-band assets, which will have good coverage but restrained speeds; 5G using millimeter wave, which will have extraordinary speed but limited coverage; 5G using mid-band that offers a mix of coverage and capacity, but might also be using 4G representing nearly half of total performance; and 5G using a mix of frequencies and spectrum aggregation.
Beyond all that, 5G devices might be connecting to two or more radio sites at once, further complicating our understanding of which network (5G, 4G, unlicensed or licensed) is being used, at a moment in time.
It soon will only be clear that a particular 5G device, on a particular network, at a specific location, works well, or does not work so well. The actual mix of networks (5G, 4G, licensed and unlicensed; cell locations used simulaneously) might vary quite a lot.
Speed and cost measurements on a cross-country basis--both fixed and mobile--have been contingent. Choices have to be made about what and how to measure (which plans, across all countries, at what speeds, price points, uptake volumes, including promotions and other buying behavior).
Then adjustments might have to be made based on household sizes (to get per-user metrics); geography (relatively more urban or rural; large or small country) or pricing power differentials between countries.
All of that will become more complicated in the 5G era, when virtually any spectrum can be used to support 5G services, with clear and distinctive coverage and capacity profiles, depending on which frequencies are used, and in what mix.
5G can be used in a legacy-free manner, though perhaps rarely, using only “new” millimeter and mid-band frequencies. It might use a combination of new and legacy frequencies (high, mid and low band assets).
5G might use spectrum within the low bands (new and legacy), or combine low and mid-band assets. Perhaps the most-common approach will be a mix of spectrum bands.
Both 4G and 5G spectrum also can be used to support a 5G device, further complicating matters.
That perhaps already is clear in South Korea, where 5G uses the mid-band frequencies to support 5G, but where, in many cases, it is a combination of mid-band and 4G spectrum that actually supports usage, although 28-GHz also is authorized and will be used, at some point.
Some recent tests have used devices able to access 1.5 Gbps of 5G bandwidth using SK Telecom’s 3.5 GHz spectrum, plus 1.15 Gbps of 4G bandwidth at 1.8Ghz, 2.1Ghz, and 2.8GHz frequencies.
The point is that 5G access is going to be quite heterogenous. There will be many ways of supplying 5G access, and performance will vary based on how the access is supplied. Even when 4G spectrum is not used (dynamic spectrum sharing, spectrum aggregation), 5G capacity will vary based on which bands of spectrum are used, and especially when millimeter wave or mid-band spectrum is available.
Low-band 5G will be faster than 4G, but less so than when mid-band and high-band assets are used.
But many early 5G deployments will aggregate 4G with 5G. In other cases 5G might be aggregated with unlicensed spectrum. In other cases, access might default entirely to 4G, when on 5G handsets in rural areas.
And 4G will keep getting faster, closing the gap with 5G using the coverage frequencies (low-band and mid-band). So even when a 5G device defaults to 4G, the speed experience might not vary too much from 5G.
The point is that interpreting 5G speeds is going to become highly contingent. Stand-alone 5G is going to be different than non-stand-alone (using 4G). 5G experience will hinge on which frequency bands are used, and what types of spectrum aggregation are possible at specific locations.
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