Looking at this code, and more broadly speaking the cellular telephony ecosystem as a whole, the best way to articulate what I feel is to point at GNS3, the net

Looking at this code, and more broadly speaking the cellular telephony ecosystem as a whole, the best way to articulate what I feel is to point at GNS3, the network simulator. GNS3 is honestly insane. It lets me run virtualized instances of the software stacks hiding inside 6..8-figure (!!) network equipment and then route packets between stuff in exactly the same way I would get if I had the physical equipment. But I personally find absolutely no substitute (as I get started/oriented) to being able to plonk a switch on a workbench and reason about it in a tactile manner. I think the same argument might be made about flight simulation: to a point, a flight simulator has nothing on just getting in a plane and flying around. In both cases, a) it's entirely reasonable to do without "the real thing" and still figure things out, and b) simulation is an such an exceedingly useful drilling and training aid that the industry as a whole would be missing something measurable without it. But it still remains that establishing a correctly calibrated fundamental sense of how everything works and how stuff gets done can be harder when using a simulator. Things might not intuitively click right away. Mental models might be a bit (or a lot) more fragmented. Complex concepts might require more juggling and mental effort to integrate and understand. So you can kind of see my frustration: I'm extremely interested in wireless communications in general (just broadly speaking) so being able to stare at all this code is awesome... with the caveat emptor that I can't legally do anything with it in the real world. The revolution of software-defined radio might mean the physical baseband aspect of 3G/4G/5G is more accessible than ever - a couple thousand now (if that, I think) instead of 5+ figures - but the relevant spectra are still licensed and locked down tight pretty much worldwide, and that's not likely to change anytime in the long term. Unlike the "I'll probably never see one of these in person" kit that I'm content to look at pictures of and tinker with in GNS3 :) wireless networking/communications does (at least to me) largely lend itself to being a very tactile subject that you just want to play with in the real world. LoRaWAN is very low bitrate and (to a cursory/long distance understanding) has a bit of friction around patents/licensing (although if I can buy premade modules that Just Work™ I'm happy) Long-range Wi-Fi is... not really an explicitly supported configuration because it gets right up at the edge of legal transmit power limits. Wi-MAX... I honestly don't get. I can't tell where it sits on the relevance spectrum. I remember reading about it years ago but it's like it disappeared at some point. Ham radio cannot be encrypted and thus represents a step down in terms of present status quo expectations on the public Internet. I'm incidentally curious how DJI's drones can get 10km line of sight. I wonder what transmit power and band(s) they're using to manage that (ISM 2.4GHz/5.8GHz?). Presumably the video transmission architecture is an eye-glaze-inducing highly specialized proprietary mess that's reasonably micro-optimized to the hilt (?). With the above in mind, is there anything up-and-coming, obscure or whatnot that I (very probably) don't know about in the space? And flipping the entire problem domain around, how can I get interested in the open source work being done in the cellular space? What interesting things can I do without any sort of base station equipment? And to what extent can I play around with cellular-band RF if I were to go shopping?