> This would be okay for experimentation. It will not be able to run as a UMTS or LTE base station or anything like that. Mostly because the software required to do that is not available and not feasible to be done "from scratch". Those protocols are huge and riddled with patent claims.
People said the same of GSM. Now we have open source implementations. It takes a long time and it's a lot of work, and it's certainly not a given that it'll work, but I don't share your certainty that it'll never happen (yes, I am aware that LTE is considerably more complicated than GSM).
> A minor issue would be that UMTS and LTE base stations need 0.1ppm frequency precision (a GPS lock) which is missing here.
A quick google suggests 0.1ppm is what the standard specifies for "local area BS". For a "home BS" (femtocell I guess) they give 0.25ppm.
From the datasheet of their oscillator chip (RPT7050A), its frequency stability vs temperature is on the range +/-0.05 - +/-2.5 ppm depending on the frequency (I didn't look at which specific accuracy it gets on the common LTE bands).
So, you're probably right that this won't make it into commercial 4G LTE equipment without using an external oscillator. However, I suspect this is plenty just to get handsets to lock on to your signal for protocol experimentation. The GSM standard has some really strict requirements for frequency stability too, but people have made workable test networks with way less stable equipment.
> I wonder if the authors misrepresent their product knowingly, or if it's just a lack of knowledge.
Lime Micro is well known, they made the RF transceiver on the BladeRF for example. They know their stuff, so I don't think it's lack of knowledge at least.
People said the same of GSM. Now we have open source implementations. It takes a long time and it's a lot of work, and it's certainly not a given that it'll work, but I don't share your certainty that it'll never happen (yes, I am aware that LTE is considerably more complicated than GSM).
> A minor issue would be that UMTS and LTE base stations need 0.1ppm frequency precision (a GPS lock) which is missing here.
A quick google suggests 0.1ppm is what the standard specifies for "local area BS". For a "home BS" (femtocell I guess) they give 0.25ppm.
From the datasheet of their oscillator chip (RPT7050A), its frequency stability vs temperature is on the range +/-0.05 - +/-2.5 ppm depending on the frequency (I didn't look at which specific accuracy it gets on the common LTE bands).
So, you're probably right that this won't make it into commercial 4G LTE equipment without using an external oscillator. However, I suspect this is plenty just to get handsets to lock on to your signal for protocol experimentation. The GSM standard has some really strict requirements for frequency stability too, but people have made workable test networks with way less stable equipment.
> I wonder if the authors misrepresent their product knowingly, or if it's just a lack of knowledge.
Lime Micro is well known, they made the RF transceiver on the BladeRF for example. They know their stuff, so I don't think it's lack of knowledge at least.