If you wonder about real world use cases for open source LTE stacks like srsLTE: They’re great for deploying small ad-hoc cells e.g. in vehicular and rescue scenarios like in our work from earlier this year: https://arxiv.org/abs/1802.09262
5G is specially designed this kid of industry in mind, so more advanced applications come in addition to the LTE markets. For example, many factories can replace their physical networks with 5G private networks for automation and robotics.
What do you need to connect to a homebrew LTE / 5g network? Can you provision your own SIM cards?
Does anyone know what it would take to configure a dual-sim phone to connect to a local LTE network at home / in the office?
In practice, you need to worry about legal restrictions -- you're not allowed to transmit on common LTE bands.
Not sure how this will actually look in the future. Is the office mobile network physically separated, or do you use the public network with special SIM cards that connect to a virtually separated mobile network?
With 5G some countries have also taken into concern a more liberal spectrum policy, which could result in more mobile network operators. One idea follows is that the spectrum would be "oversold" by selling the same frequency to organizations tied to particular cities, for example.
Finally, there is the notion of virtual SIM cards. And as far as I know, alternatively you could also just hack the LTE server to accept each incoming connection (with any SIM) and use a challenge after the Internet connection is established, and then just kick out any device which doesn't send the magic packet.
I was hoping 5G had taken this use case into account, and thought to optimize for those bands, or alternatively allow for use of 60 GHz, or something where i can get a local license for usage of that band.
You can achieve network separation APNs, so there is no need for such a hack.
The question I have in mind is: Does your office advertise it's own PLMN with WiFi-like equipment, or do you outsource your office wireless network to an established operator which handles authentication and provides a virtual, separate network?
Regarding your question, I recall reading a paper which compared both cases: the office owning the whole infrastructure, and one in which it is rented/outsourced to an established MNO. While the paper suggested that both use-cases are plausible, in practice your preference is likely to vary depending on local regulation and use-case (e.g. latency requirements etc.).
In Android devices everything worked as expected. However, none of the iOS devices associated with this network, although the devices did support the LTE band for that network.
Speculation was that there is a PLMN (cellular provider identifier) whitelist in Apple devices, which could not be worked around.
The radios we used were simple VHF radios on licensed frequencies. There was no encryption which meant anyone could listen in, so obviously we weren't allowed to discuss personal details over the radio. Depending on the actual event we may be covering a large area or uneven terrain, so the radios may not always work.
For backhaul we'd either use our phone if we needed to call the emergency services or for larger events we'd have them onsite so they would forward the message on - for example to warn a hospital of an incoming patient (often it was in remote areas where the nearest hospital had limited A&E facilities) or to call an air ambulance.