Also there are several other companies that have a lock on that thing.
When I worked at QCOM at one point I had access to that the 3g versions. My boss had printed it out. It was about 2 inches thick single spaced double sided. Rumor was the 4g one was double that. Then there was the 'chipset'/serial interface about the same size.
So could you re-write one? Yeah (given the time for it). Never mind the legal tangle that bcom, qcom, marvel, whatever Motorola is these days, Huawei, ZTE, and others have built around it. That would just be the technical. Then getting it onto a real cell network would take a lot of work. You prob could make your own in a unlicensed band though if you stuck inside the power limits. Title I/II determine what people can and can not do with the US networks. Think the current thinking is physical connection you can do quite a bit, but radio it is locked down. But I could be wrong.
I'm no expert in this area, so I'm just going to ask: suppose you implement the entire 4G standard, but alter the used frequencies to a range you can legally transmit on (say, the 2.4GHz or 5.2GHz range), would the technology be different enough that it couldn't be adapted into a real 4g modem by changing the frequency range the device operates at? Is there some inherent technical challenge that makes the technology operate around 1600MHz but not around 2400MHz?
LTE has some advantages over WiFi (i.e. the IoT features, the roaming features, the endpoint management features) so I can see a 2.4GHz LTE network being quite useful in some edge cases. With open technology, private LTE networks can probably serve quite nice business use cases.
Not only is this possible there is actual spectrum dedicated to this kind of purpose https://en.wikipedia.org/wiki/Citizens_Broadband_Radio_Servi... though there are a lot of other rules around it (e.g. some slices can be allocated in a given region to a licensed user but not all of the slices in a region).
This is not only possible, it's already a thing with unmodified hardware. The 900 MHz band is a ham radio band in the US, but it's used for GSM in Europe. That means that you can quite legitimately set up a GSM base station in the US if you have a ham license, as long as you abide by ham radio regulations (which might require some hacks), e.g. you can't turn on encryption and you need to broadcast your callsign periodically. Then most multiband phones will connect to it thinking it's a European GSM network. I can't find it right now, but I watched a talk where someone described doing just that.
900MHz is also used for LTE in Europe, so I'm pretty sure you could do the same thing with 4G/LTE.
The particular bands the cell providers run in were sold to them by the government (or bought from someone else who got them from the gov). If I remember correctly it was mostly the antennas lengths and what the tuner was set to for the chipsets (some being fixed, some being more SDR). Some bought those particular bands because they tend to penetrate buildings better than others.
But yeah if you could keep inside the power levels, and stay in the unlicensed bands, and keep out of trouble with the patent courts you probably could make an LTE network. I would not be surprised if many of the chipsets already could do it. Power levels would be your biggest hurdle for something more than a test network.
When I worked at QCOM at one point I had access to that the 3g versions. My boss had printed it out. It was about 2 inches thick single spaced double sided. Rumor was the 4g one was double that. Then there was the 'chipset'/serial interface about the same size.
So could you re-write one? Yeah (given the time for it). Never mind the legal tangle that bcom, qcom, marvel, whatever Motorola is these days, Huawei, ZTE, and others have built around it. That would just be the technical. Then getting it onto a real cell network would take a lot of work. You prob could make your own in a unlicensed band though if you stuck inside the power limits. Title I/II determine what people can and can not do with the US networks. Think the current thinking is physical connection you can do quite a bit, but radio it is locked down. But I could be wrong.
Have to check that proj out. Looks cool!