Problem connecting to NanoBTS with current version of OpenBSC

This is merely a historical archive of years 2008-2021, before the migration to mailman3.

A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/OpenBSC@lists.osmocom.org/.

Andreas Schmidt-Dannert aschmida at mailbox.tu-berlin.de
Tue Sep 7 11:57:56 UTC 2010


Hello all,

since last weekend GPRS is working and now I am about to understand what 
exactly happens when I turn on my Milestone to get a position fix in 
googlemaps.

As I understand it, the phone (SET) queries the SUPL server (SLP) of 
Motorola to get assistance data. I can see in wireshark that they talk 
for a while but unfortunately I can only see the TCP packets.
Of course I would like to see the ULP packets inside of TCP.
Wireshark supports ULP but I cannot see the packets. I attached a capture.
Does someone here has a ULP capture to share? Or can someone acknowledge 
that he/she can see the ULP packets?

I can only see the DNS query for the ip of the SUPL server and than some 
TCP packets going to the SUPL port (7275) and back to my mobile phone.

  ULP is implemented and so maybe it is my version of wireshark which is 
the development version from https://launchpad.net/~dreibh/+archive/ppa

Another thing is that I get placed in googlemaps to Sao Lazaro (Macau) 
which is not really Berlin. It only happens when I am connected to the 
NanoBTS and no other position can be retrieved. It happens with a Nokia 
phone (N78) as well as with one from Motorola (Milestone).
This is not a problem since it goes to the right position as soon as it 
has found enough satellites but indoors and without A-GPS working it 
places me to Sao Lazaro. Just curious what that could mean.

Best,
Andreas


On 08/22/2010 11:35 PM, Andreas Schmidt-Dannert wrote:
> 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"<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
>
>
>
>

-------------- next part --------------
A non-text attachment was scrubbed...
Name: supl.pcap
Type: application/cap
Size: 2179 bytes
Desc: not available
URL: <http://lists.osmocom.org/pipermail/openbsc/attachments/20100907/149db4c5/attachment.bin>


More information about the OpenBSC mailing list