The Range of 5G Band n78

Over the past weeks I’ve noticed a few articles, posts and videos on the net that were looking at first 5G deployments in the wild and were commenting on the seemingly limited range of the 3.5 GHz band that is used for 5G NR. Some people noted that only 200m from the base station they could no longer use 5G and fell back to LTE. Therefore, they concluded, the range of the n78 frequency band must be very limited. But is this really so?

In practice, the main reason for 5G disappearing quickly when moving away from a 5G covered area is that in cities, base stations are typically 250-500m apart from each other. When walking away from a 5G enabled base station into LTE-only territory, the LTE signal of the non-5G enabled base station typically becomes stronger after about half that distance. And once that happens, a handover is performed to the LTE-only base station and hence, the 5G bearer, and, as a consequence, the 5G logo in the status bar goes away. That does not mean the n78 coverage has gone but it just means the UE has been handed over to another base station that does not add a 5G bearer.

It is of course true that the range of a signal in the 3.5 GHz range is shorter than, let’s say the 800 MHz or 1.8 GHz range that is often used in cities for the LTE coverage layer. If all things are equal! But they are not! 5G NR deployments often use Active Antenna Systems and are thus capable to beam-form both broadcast and dedicated channels This in effect not only increases individual data rates but also the range of the signal. Some say, and unfortunately I don’t have a reference for this, beamforming extends the range of the n78 band to be equal to band 3 (1.8 GHz). Also, beam forming generates a stronger n78 signal at the edges of an antenna sector compared to ‘conventional’ flat panel antennas used by LTE. This effect should also not be underestimated.

So for me, the real test of the range of band n78 will be in-building penetration inside a 5G coverage area. If one can still receive the LTE anchor cell but without a reasonable signal on band n78 then we will know more.