
Sprint's magic box - asimpletune
http://newsroom.sprint.com/news-releases/sprint-announces-worlds-first-all-wireless-small-cell-the-sprint-magic-box.htm
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Animats
T-Mobile has a similar box. But it comes as two units. One unit connects to
the cellular network. The other is a microcell. The two communicate
wirelessly. You put one where it can see a tower, and the other where you have
a dead spot. I have one of these because there is a hill between me and the
nearest T-Mobile cell site.

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TrainedMonkey
T-Mobile has something even better, you can use WiFi instead of cellular
connection on compatible phones:
[https://support.t-mobile.com/docs/DOC-1680](https://support.t-mobile.com/docs/DOC-1680)

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zkms
Yeah -- "wifi calling" (running LTE signalling/data over an IPSec tunnel over
wifi) is frankly superb -- I use it all the time, it seems to reduce battery
drain (I imagine there's somewhat less use of the LTE modem), it even works on
my phone (iphone 6 on t-mobile in US) when it's in _airplane mode_ with wifi
enabled.

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bearble
I've been using a Sprint AIRAVE*[1] in my home for almost three years. This
product seems to do something similar but without the requirement of your home
network

It's been a must have for my in now both a low-income city and rural New
Jersey. Without the extra signal support I am constantly dropping calls and
having the audio cut out.

[https://www.sprint.com/landings/airave/](https://www.sprint.com/landings/airave/)

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Animats
I had a Sprint AIRAVE. It needs GPS to tell it where it is. Not just at setup,
but constantly. That's strange. It also has the serious defect that it
publishes itself as a strong cell site even if it loses its Internet
connection. So if your Internet connection goes down, so does your cell
service, until you unplug the thing.

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sbierwagen
TDMA needs accurate clocks to work. All cell sites have GPS receivers in them
for time signal reception.

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zkms
People with a better understanding of the LTE protocols than I do -- is it
possible to make an LTE relay (like this "magic box") but without any
cooperation from the network operator (so no access to any cryptographic
keys/secrets and no special/internal access to the operator's network)?

I know that to avoid self-interference, the relay needs to either implement
frequency separation between its link to the real eNB and its link to the UEs
it serves, or implement time separation. AIUI, time separation gets done by
(for DL) not transmitting to real eNB when needing to listen to UE and (for
UL) by not transmitting to UE when needing to listen to eNB. I think this gets
more complicated when DL and UL are in the same band (TDD LTE).

Since I have no access to any key material, I cannot read anything that's
encrypted and I cannot modify anything that'll get verified cryptographically
or gets used as an input to a KDF (changes in KDF inputs will lead to
different keys on the UE than the network expects). Given this limitation, is
it possible to either:

1\. Demodulate signals from the real eNB (on its DL band), replace any
reference to the real DL band (in the master/system information blocks) with
our DL band, and radiate that _on a different DL band_ to the UE -- and do the
same transform with the UL bands. Is it possible to fool the UE this way? Is
the UARFCN used as a KDF input or talked about over some signalling radio
bearer in RRC / NAS messages (which afaict, is encrypted and thus
inaccessible)?

2\. Is it possible to intercept/consistently modify/pass-on scheduling
requests / resource grants for both UL and DL without breaking anything? Are
scheduling requests / resource grants ever encrypted or otherwise protected by
cryptography? Does anything above that layer actually know/care about the
precise scheduling? Would this be a feasible method to ensure that there's no
self-interference at the relay (by telling the UE to radiate on UL at a
different time than the relay will radiate on UL to the eNB, and similarly for
DL)?

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Maven911
It's been a while since I have been out of the wireless telco. world, but is
this really new tech, the notion of having small cell sites for businesses ? I
think it happens all the time, just maybe not with LTE Plus per say.

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Gaelan
It's quite common, even in the home. The ones I've seen all need an Ethernet
link however--maybe that's the innovation?

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dublinben
Those are probably proper femtocells, that broadcast a new cellular signal.
These are repeaters or dumb signal boosters, that rely on a cellular
connection back to the actual network.

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batoure
The Press release implies that what they have done is use their newly acquired
low frequency spectrum to create a carrier signal that only those boxes can
pick up on then the boxes rebroadcast at frequencies existing smartphones can
interact with.

The lower frequencies will in theory have better range than the higher
frequencies they use for typical LTE

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arnon
Isn't this just a souped up femtocell?

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resoluteteeth
In technical terms it's a femtocell, yes. But if they're handing out
femtocells that themselves connect over the cellular network that users can
just dump on a windowsill to improve their signal with no configuration,
that's somewhat interesting, and different than how carriers have been
deploying femtocells until now.

