5G – How Much Spectrum Do You Need To Make A Difference?

The current situation around 5G reminds me a bit of how things were a decade ago when first 4G LTE networks came on air. Network operators in the US launched LTE with 10 MHz of spectrum and overall, their LTE networks where not much faster, if at all, compared to 3G UMTS/HSPA in Europe that could aggregate two 5 MHz carriers. So will things be different now that we are moving from 4G to 5G? Or, in other words, how much spectrum do you need for 5G to make a difference for users?

It seems different parts of the world will launch 5G in different ways. Press reports and papers such as this one from the GSA give interesting insights.

The 5G Situation in Europe

In Europe, network operators that provide high capacity to their users today use around 50-60 MHz for downlink (and an additional 50-60 MHz for uplink) LTE channels today. Historically, the two numbers are not aggregated to a total but the configuration is simply given as 50 MHz. Today, some network operators in the US seem to add the two numbers together to look better but I won’t do that in this post and on this site in general. Be careful when you read an article elsewhere about how much spectrum an operator uses, they usually don’t mention if it is a single or combined up/down value they are writing about. Anyway, this is quite a bit of spectrum used and for 5G to make a difference, a network operator would have to use at least the same amount of spectrum for 5G or preferably even more for users to really notice a difference.

In Europe, most network operators that have publicly announced 5G plans want to use the 3.5 GHz band (3GPP band n78) in which around 400 MHz of bandwidth is available. In theory that’s not too bad and if there were 4 network operators in a country, each could get 100 MHz. This is also the maximum bandwidth a 5G channel can use without some sort of 5G carrier aggregation and about twice the amount of spectrum used for LTE today, even in high-end networks. Speeds that can be achieved by combining the 50 MHz spectrum used for LTE and 100 MHz of spectrum assigned for 5G will be significantly higher than what is possible with LTE today. The major catch is that the range of a 3.5 GHz 5G signal even with beamforming will likely be lower than the range of an LTE signal on 1800 MHz (3GPP band 3) which is used as the main coverage and capacity layer in cities today. The difference is even greater when on compared to the range of LTE on 800 MHz (3GPP band 20), which is widely used as coverage layer in rural areas.

To bring 5G to rural areas, one could use the 700 Digital Dividend II spectrum (3GPP band 28). However, network operators typically have around 10 MHz of spectrum in this band, the same amount they typically have in the LTE 800 MHz band (3GPP band 20). That means that from a throughput point of view it will not make a huge difference. And from a technical point of view, one could also put an LTE signal on 700 MHz and would reach the same speed. First operators already do this today. So putting 5G NR on 700 MHz would mostly be a publicity thing rather than provide real benefits compared to putting LTE into that band.

The 5G Situation in the US

On the American continent the story looks very different. Here, Verizon has come up with a pre-5G 3GPP derived but not compatible spec for fixed wireless access. The system doesn’t have mobility and will be used to compete with copper, cable and fiber home access by using spectrum in the 20-40 GHz range, the so called millimeter waves (mmWave).

Others like AT&T have waited a bit for 3GPP to have some sort of usable 5G spec available for mmWaves and will start offering a 5G service in this frequency range including mobility for smartphones, tablets, etc. The major challenge with mmWaves in the 20-40 GHz range is that the signal range is likely to be even more limited than the 3.5 GHz band used in Europe. Also, mmWaves require an antenna array in mobile devices and the whole approach will stand or fall depending on how well beamforming can increase range. I have a hard time imagining how such a deployment could be useful in practice if the range of a 5G mmWave cell would be similar to the range of a low power Wifi hotspot today. But perhaps the range is better than that and I can only speculate today. Only real networks and real devices will tell in due time.

T-Mobile US wants to deploy 5G in the 600 MHz band (3GPP band 71). That sounds good as with this spectrum one can create a nice 5G coverage layer. In fact T-Mobile already does that today by using this spectrum for LTE. 3GPP band 71 has a total bandwidth of 35 MHz and it seems that T-Mobile has 15-20 MHz of that spectrum depending on the location. If some of that spectrum is used for LTE then there is not much left for 5G. So as nice as it sounds at first, putting 5G next to LTE in this band will make little to no difference compared to what is possible today.

Sprints plans for 5G have yet another spin. They have announced that they will use their massive spectrum reserves in the 2.5 GHz band to launch 5G. I’m not sure but I doubt they have 100 MHz there they could use, but still I can imagine that even half that amount of spectrum used for 5G would significantly increase their data rates, not only close to the cell site but as far as their LTE signals go today. And here’s the special twist: Sprint and T-Mobile intend to merge if they get regulatory approval which would mean they could put 5G on 600 MHz and 2.5 GHz for their customers and thus have coverage and capacity. In other words, Sprint would have a similar 5G setup as network operators in Europe.

The 5G Situation in Asia

In China, network operators will likely use spectrum between 2 and 5 GHz with channel bandwidths of up to 100 MHz. Telegeography has some interesting information here. In other words, the situation is similar as in Europe. Network operators in Japan seem to have a double strategy and want to deploy 5G in 4.5 GHz and mmWave bands simultaneously. According to the Telegeography report, Korea is on a similar path. This is different from the US, where operators will either use traditional frequency bands or mmWave at the beginning but not both at the same time.

Summary

As you can see the situation is quite diverse at the moment while the main stream press just talks about 5G network rollouts. Which network operator in which part of the world has the better strategy? It’s hard to tell at this point because from a technical point of view there are many technological firsts and unknowns in this game. The only thing I’m sure about at this time: Deploying 5G in less than 50 MHz might be enough to put a 5G sticker on a network but it won’t make a real difference to customers compared to using the same spectrum with 4G LTE.