It's too bad srsRAN doesn't support TDMA (yet). LTE band 42 and the 9 cm amateur radio band overlap, so it would be legal for hams to run LTE/5G nodes.

Having your phone being your first ham radio might be a great way to get younger folks into the hobby.

Yeah, once TDD is implemented, things will get interesting for sure - also the CBRS band will open up opportunities for much lower cost radio devices that can have some "serious" range (i.e. small neighbourhood scale WiFi AP) - maybe we'll see that new generation get into ham, and also learning more about networking and launch their own metro-net ISPs?

One minor thing - hams would need to be careful they can run LTE/5G "out the box", given most setups use an encrypted layer to the base station. You can turn that down to zero confidentiality (EEA0) but still using integrity checking (EIA>0), but I am not sure if that's a particularly well-supported mode of operation.

I believe you can also satisfy the encryption requirement by publishing the keys, fwiw

There's also the 13cm band (2300-2450MHz) that overlaps in part or fully TDD-LTE Band40 and FDD-LTE Band30.

North americans also have 902-928MHz 33cm band, but that lacks the paired spectrum above it, so FDD-LTE or GSM are not possible. And I don't think there's a widely supported TDD-LTE spec for it.

Thanks for pointing out band 40. Apparently it's just used in China, but it is supported on the iPhone 13.

Band 30 is a no-go because the downlink is at 2350 to 2360 MHz, which is not a ham band. The ham band is split because of satellite radio. It's 2300 to 2310 and 2390 to 2450 MHz.

Band38 is the one most 2.4 GHz WiFi-covering half-duplex SDR can handle, at least if modified/adjusted with a local oscillator quartz suitable for LTE. It's an ugly fraction to synthesize with a fractional PLL to LTE-specs of local-oscillator-quality.

Yeah, it's not ham, but low power levels and RF-shielding-cages should suffice to keep radiated emissions far below interfering levels.

It's also surprisingly well supported, at least on non-US handsets, from when I researched it a bit a few months before the first wave hit and blocked collaborative hardware hacking.

The 13cm band is a bit of a mess globally. Here in Finland it's still full 2300-2450MHz. But in 2300-2320MHz it is shared with lightly licenced "provate LTE". Hop over to Sweden and it's 2400-2450MHz only with a powerlimit under a watt.

And im USA it's that pumctured mess, isn't there also AT&T running Band30 FDD-LTE? Years back when I was searching for LTE phones with Band30 for hamLTE use I only found AT&T carrier locked stuff from USA.