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Andreas Schmidt-Dannert aschmida at mailbox.tu-berlin.deHello 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"<aschmida at 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