R: Need info on AGPS

[Marcus Bauer]

On Thu, 2007-01-25 at 16:24 +0100, Harald Welte wrote:

> > 3. A-GPS involves additional data traffic and thus (potential) additional
> > costs. Does it use a normal GSM/GPRS IP-based data transfer? does it use
> > some out-of-band GSM/GPRS control messages? or does it get data from
> > broadcasts in the local cell (e.g. GSM cell-broadcast)?
> 
> AFAIK: GPRS.  so its up to you whether you want that extra traffic (and
> cost, unless you're flat) or not.

The Global Locate docs state TCP/IP as one possible way. So via
USB-network or BT should be possible too.

Source (gpsd aka Global Locate Library):
http://www.globallocate.com/SEMICONDUCTORS/SEMI_DRIVER_Frameset.htm

> > 4. if the answer to above is GPRS: is it possible to estimate in advance how
> > much additional traffic (in Kbytes/day of full operation)?
> 
> I am sure it's a quite fixed amount of

You need it only once for the first fix. It is ~2KB for all satellites
and valid for 2-4 hours. Precomputed for a week maybe 1MB.

Marcus