LTE TDD-TDD Carrier Aggregation – Band 40

I’m traveling (again) in Europe these days and in most countries, the frequency bands used for LTE carrier aggregation are pretty much the same: Band 20, 1, 3, 7. I’ve come across a few band 28 (700 MHz) deployments, like for example in Paris, France, and even LTE TDD band 38 in the 2.6 GHz duplex gap, which is used in Sweden and in the Netherlands. I’ve never seen anyone using band 40 in Europe, however, i.e. spectrum in the 2.3 GHz range. Until recently…

Band 40 sounded so strange to me, I had to look it up in the LTE frequency band list. In my case, I observed it while waiting in the Eurostar terminal at London St. Pancras. The network operator deploying it in this case was Telefonica/O2 UK. What was even more interesting was, that they were using band 40 – band 40 carrier aggregation. That makes me wonder how many devices actually support band 40, and, on top of that, band 40-40 CA!? In my case, I used a somewhat dated 2019 Samsung S10. So there must be quite a few these days.

And interesting side note: I only caught this by accident. While in the Eurostar terminal, there was massive congestion on the default roaming network my device used, so I started to hop from network to network. Over at O2, I at least got 5 Mbit/s while in the waiting area. This was far from brilliant, but light-years away from the congestion on other networks. So I decided to check what O2 was doing differently.