Hello Dieter,
On 08/22/2010 10:17 PM, Dieter Spaar wrote:
Hello Andreas,
On Sun, 22 Aug 2010 21:03:46 +0200, "Andreas
Schmidt-Dannert"<aschm...@mail.tu-berlin.de> wrote:
I am playing around with RRLP and since newer versions of OpenBSC also
support packet data I wanted to upgrade to be able to receive A-GPS
data from the internet.
I don't know whats wrong with your configuration, I can just say that
here switching between different PCs running OpenBSC works without problems
when the correct OML IP address has been configured for the nanoBTS ("-o"
option of "ipaccess-config") and the nanoBTS was restarted.
I am interested in what you want do try with RRLP because I recently
did some more experiments with it. Especially I would like to try
"MS-assisted" position measurements next, however this method requires
the acquisition assitance data which have to be calculated first, I don't
think they can be extracted from the data of a GPS receiver. I don't know
if there is some ready and tested code for this already available which
would make it easier to get this up an running.
Best regards,
Dieter
The idea is to find out what information can be revealed from a phone by
sending different RRLP requests. Right now only ms-based positioning is
possible and I played a bit around with it and was surprised how easy it
was to get the position. I wonder if they even store the last known
position? As far as I know it makes it easier to compute a new position
if the phones knows where it roughly is. Anyway since I just have one
nanoBTS I can only use GPS as positioning method and while I was playing
around I realized that most MS asked for assistance data (as you also
found out at HAR2009).
So bringing ms-assisted positioning to work is also a goal of me.
Is it not possible to just transfer the acquired data from the GPS
receiver in the MS to a A-GPS server in the network and let te server
compute the acquisition assistance data? Probably I am thinking to naive
here. I know it should be a server not too far away from the asking MS.
By the way there was for a while a rrlp-ephemeris tree in openbsc. What
was it for and what happend with it? As i understood it one could
connect an external GPS device to a laptop to get data that is
needed..kind of an A-GPS server. Right?
Another tought: What about SUPL?
SUPL uses IP to get assistance data from a SUPL server...so maybe it is
possible to use a supl server from google or similar?
So what I do is just playing around to find out what can be done (old
positions, will a phone turn GPS on when an RRLP query comes - thinking
about emergency cases (E911) this would make sense) and how do
different mobile phone react to different queries. I am not fuzzing - I
am sending only valid queries. I am quite new to this field but I find
it very interesting and I have fun working with OpenBSC (if it works :)
maybe my problem has nothing to do with OpenBSC...I do not know).
If you have any ideas how to get ms-assisted positioning to work I would
be glad to hear about it.
Best,
Andreas
