Gil -
Thanks! Very Interesting!
My iPhone does have a "field test mode" (*3001#12345#*) which does
expose the alternate towers that it sees (and might use). I see no
indication anywhere that I could influence it's choice, nor have I been
able to find a concise description of the algorithm/heuristics likely
used to decide. The most obvious of course, would seem to be signal
strength, but that ignores issues such as congestion.
Since GSM is a Frequency Division Multiplex hybridized with Time
Division Multiplex, it seems like there would be almost immediate
feedback to the mobile device as it tries to connect as to whether there
even *was* an available time/frequency slot to use... the heuristic
could be as simple as "try the strongest signal you see, if it is full,
try the next, repeat".
Along with a dB indication of (useable?) signal there is something
called RSSI (received signal strength indicator) which seems useful for
recognizing how much interference in the band there might be. It tops
out at about 50 underneath a tower but is as low as 5 when still
useable. Multiple towers competing and/or possibly other sources of
interference run this number up without running up the "useable" signal.
There are two very cryptic numbers, C1 and C2 which from the mumbo jumbo
I've found, might relate to the heuristic which I was seeking above...
but I don't know yet... this is subtle and complicated stuff and it
appears that short of finding a professional training course, there
isn't much information laying around for the motivated layman.
See what we have become in this Internet/Google/Wikipedia age? We DO
expect a LOT!
Depending on the phone there might be a # code to get it to search for
more frequencies. Might take a bit of diging though. My oold Cinguluar
phone for instance used #689# that let it borrow other towers in
range. I'll check for the potenial andriod # codes to see if there's
something simillar.
On Fri, Oct 7, 2011 at 12:45 PM, Steve Smith<[email protected]> wrote:
I'm hoping *someone* out there knows more about this than I do, though none
of the earlier discussion seemed to bring any of that out.
I took up Gary Nelson's question about Cell Towers/Coverage, my own
frustrations, and the other resulting conversations to do a little research
and see if I could learn more and maybe even fix up some of my own
problems/challenges.
I'm testing iPhone 2, 3G, 4 against ATT and T-Mobile SIMS right now. Mostly
at my house (very marginal signal if any) but will be doing other places.
I'm looking at Cell Repeaters (primarily for my home, but maybe also
mobile). I'm therefore *mostly* sorting out GSM related issues, but there
is a lot of overlap in general RF issues, repeaters, tower locations, etc.
I started trying to write up what I know (so far) and discovered that (as
often is the case) the more I know, the more I know I don't know. My 3rd
Class Radiotelephony license from 1974 and a BS in Physics provides just
enough background to get me in trouble. I wrote a long, rambly overview of
what I know (dominated by what that made me realize I *didn't* know) and
decided most of you don't care.
So, if there are others trying to make actionable sense (or merely slake
your curiosity) about the issues of Cell Reception and the potential use of
Repeaters, ping me and we can discuss offline. Maybe once we learn enough,
one or more of us can write up a (more) concise "lessons learned".
My long-winded ramble was useful (to me) already, as trying to explain it to
the larger crowd caused me to dig just a little deeper than I was for more
"practical" reasons. Now to get my nose back on the practical grindstone.
- Steve
--
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FRIAM Applied Complexity Group listserv
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============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
