Verizon femtocell GPS question

justen

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harshness: Authority to operate in a given area (and, if so, which spectrum to broadcast and receive on flows from that), I guess, is probably the most important?

But without GPS for time, it wouldn't work. While NTP might be easier as you argue, it can be exponentially less accurate (GPS time being accurate to ~1 microsecond, NTP being accurate to ~10 to ~100 milliseconds). LTE and CDMA need accuracy greater than NTP can predictably, reliably provide.
 

harshness

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LTE and CDMA need accuracy greater than NTP can predictably, reliably provide.
My Moto E5's display clock is currently around three seconds fast as compared to my UltrAtomic radio clock yet it seems to function just fine. Given this disparity, I wonder if whatever the communications technology requires is built into the radio signal rather than being precise time-of-day dependent.
 

justen

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My Moto E5's display clock is currently around three seconds fast as compared to my UltrAtomic radio clock yet it seems to function just fine. Given this disparity, I wonder if whatever the communications technology requires is built into the radio signal rather than being precise time-of-day dependent.
The Network Extender and other femtocells, as network elements, are where the time synchronization issues come into play. Your user equipment is fine — it wasn't all that long ago that end-user devices didn't have GPS. (And because GPS signal can be fleeting indoors, I don't know that any UE OS depends or even refers to it for time. But unplug the GPS antenna or puck from your femtocell and it'll stop broadcasting almost immediately.)
 

harshness

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But unplug the GPS antenna or puck from your femtocell and it'll stop broadcasting almost immediately.)
I'll try that later today. I have a T-Mobile Internet-based cell at work and I can put the puck inside a steel file cabinet (close enough to a Faraday cage for this purpose).
 

Foxbat

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Our T-Mobile femtocells at work don’t require the GPS antenna since they are registered to our Company’s address. I have one that was located close enough to a south-facing window that it can get a GPS lock but the rest are located inside enclosed areas with no GPS reception. The GPS LED blinks amber on those units.
 

justen

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Our T-Mobile femtocells at work don’t require the GPS antenna since they are registered to our Company’s address. I have one that was located close enough to a south-facing window that it can get a GPS lock but the rest are located inside enclosed areas with no GPS reception. The GPS LED blinks amber on those units.
GSM/UMTS and CDMA have different tolerances, but my guess is T-Mo is willing to accept/deal with out-of-sync situations with LTE more creatively than Vz/Sprint/T.

Sprint handled things somewhat similarly with the original (Samsung-built) Airave and only required a GPS lock at boot. Eventually, it would lose sync (weeks or months) and would reboot itself. Reading about the CellSpot, sounds like they put an override on their side so that it skips the GPS check if they have an E911 address on file for you as you mentioned.
 

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