My word on GPRS (was: How Slow Is Fast?)
Michael 'Mickey' Lauer
mickey at openmoko.org
Thu Jul 3 21:35:06 CEST 2008
Am Donnerstag 03 Juli 2008 08:21:50 schrieb Knight Walker:
> Anyone who has paid attention to this mailing list over the last few
> months has seen the "It doesn't have 3G, it's worthless" messages about
> the FreeRunner. For me (And many, many others) having a fast,
> power-hungry wireless pipe to the phone isn't as important as everything
> else the FreeRunner brings to the table. But I do have a question: What
> kind of thru-put can we expect to see from the GPRS radio in the
> FreeRunner? Is it 2k/sec dial-up speed?
I have just did some measurements and I have achieved a sustained throughput
of about 5K/sec. It's not stellar, but you can actually do a lot with that,
if you're a bit clever. People have lived for decades with slower landline
> Also, and I know this has been talked about before, but is the final
> word that the GPRS can or cannot be active at the same time as the GSM
> (Class B or whatever it's called)? An ongoing GPRS connection would be
> really nice but if it can suspend/resume decently (Something like v.92
> on modems if anyone remembers those).
I just did some tests with our framework and here's my first (not final) word
You can activate a GPRS context, have the ppp0 interface automatically setup
and transmit data.
Two cases now:
a) If you want to dial out, just dial out. The ppp0 interface will keep being
up, but will not be able to transmit any data while you're calling, e.g. a
wget will be stalling, pings will hang. Once you hangup, the context will
automatically be resumed, wget will continue, pings will return.
b) If you want to receive calls, the connection needs to be idle. You can
safely have an activated context (i.e. i was able to log in via SSH) being
idle and then you will get your incoming call notifications.
Note though, once someone wants to call you while you are not idling, i.e.
during a long wget, you will not get any call notifications. Instead, the
network will think you are not reachable and -- if configured -- send you to
the voice mailbox.
All in all, considering the age of the TI Calypso, I'm quite satisfied with
the possibilites this gives us.
Yes, it's not perfect. Yes, I'd love to have more. But I can already do a lot.
Hope that helps,
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