Hi Mychaela,
Your concerns are understandable given what happened e.g. in Australia
earlier (they switched of 2G completely). However the current trend
amongst operators seems to be keeping 2G and 4G while switching off
3G. 3G turned out to be the worst technology for carriers, because it
does not have good coverage for simple voice calls and also it is
quite cumbersome to operate while data rates are inadequate for
today's subscribers. So this means 2G is kept for good coverage, basic
voice service and 4G is kept for high data rates, assisting 5G in
coverage etc.
Some coverage about this in the news:
https://www.vodafoneziggo.nl/en/verhalen/end-3g-era/
https://www.telekom.com/en/media/media-information/archive/bye-bye-3g-now-l…
Of course in the US the situation might be different because of
frequency allocation differences, nevertheless I'd still place my bets
on 2G staying with us for a long time. Naturally you are free to do
whatever you wish, and having a BTS at home is great in many cases
even if commercial service is available as well. I just wanted to
chime in on the discussion about 2Gs possible future not trying to
change your mind.
I only have limited knowledge about BTS ranges, one time I tried to
operate a BTS with an SDR board (USRP B200) and you could probably
guess how bad it was :) - inaccurate clock, almost no TX power,
resulting in a mighty 5m or ~6yards :). With a good clock source and
an amplifier though I think even with an SDR one could have good
ranges, however the burden of operating a complete PC just for
handling the SDR makes buying a nano/sysmoBTS much more attractive.
Kind regards,
Domi
On Fri, Nov 20, 2020 at 6:25 AM Mychaela Falconia
<mychaela.falconia(a)gmail.com> wrote:
Hi Caleb,
Thanks for the explanation regarding "proper" BTS setups having much
more sensitive antennas for receiving uplink.
In my case, I will be operating my BTS indoors inside my apartment (no
tower), it will be a sort of clandestine operation squatting on an
unused frequency *without* the usual billion dollar license, and the
antennas hooked up to the Tx & Rx ports on the indoor BTS will be the
ordinary omnidirectional kind. At first I was thinking about using
the same kind of 5 cm antennas as these ones sold by Sysmocom:
http://shop.sysmocom.de/products/ant-sma-quad
I have a big bag of SPK ECL antennas similar to the above, except that
mine are the straight version - I use them with all of my GSM MS
development boards - but now that I think about it, there is another
antenna which probably has higher gain which I can probably use for
the BTS:
https://www.sparkfun.com/products/8347
If I use either of the above, the Rx and Tx antennas on my BTS will
probably be a little better than the internal antenna built into most
cellphones, but it will be comparable to the MS antenna if the MS is
one of my development boards. :)
The two BTS models I am currently considering as my top choices are
either the PCS band version of ip.access nanoBTS (used from ebay) or
sysmoBTS 1002, and both of these seem to have the same maximum Tx
power output of 23 dBm. Am I correct in assuming that if my BTS puts
out 23 dBm, then I will hit my range limit when the MS stops being
able to hear the BTS, before I hit the limit in the uplink direction?
Any guesses as to what kind of range I should expect?
I don't expect that my illegal BTS will ever serve any users other
than just me - as I understand it, the total number of people *on the
entire planet* who would voluntarily wish to use a 2G phone (as
opposed to 5G/whatever) will never exceed maybe 10 users max
planetwide, and I am pretty certain that right now I am the only
active 2G user in all of California, if not in all of USA. As of
today, T-Mobile USA still has active 2G service across all parts of
California which I frequent these days - my travels nowadays are much
less than pre-Covid, but I still occasionally drive as far south as
downtown San Diego and as far north as almost hitting LA, and so far I
have working service almost everywhere. But I can only reason that
all those GSM cells must sit there 100% idle with exactly zero traffic
almost all of the time, except during those brief moments when I
happen to drive by that cell in my car - I don't see how it can be any
other way when absolutely everyone else has standard sheeple 4G/5G
phones. The only T-Mobile 2G cell that has nearly constant activity
on it is the cell that serves my apartment, as that is where I stay
99% of the time in this Covid-driven reality.
Thus I can only reason that T-Mobile USA currently maintains a GSM/2G
network that has *only one active user* perhaps in the entire country,
so it is understandable that they are threatening to shut it down. If
they shut it down before I kick the bucket, I am thinking of setting
up my own illegal BTS (on the very same ARFCN on which wrongfully-
shutdown T-Mobile service used to be) inside my apartment, connected
to a VoIP tunnel on the back end. It won't help me at times when I
have to drive somewhere, but it would be neat if it can cover areas
within walking distance of my apartment - the two grocery stores in
our little rural town both happen to be within walking distance.
Sorry for ranting,
Mychaela