OpenBSC

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4315 discussions

Re: GSM license approval for HAR2009
by Dieter Spaar 22 Jul '09

22 Jul '09

Hello Stefan, On Wed, 22 Jul 2009 19:36:16 +0200, "Stefan Schmidt" <stefan(a)datenfreihafen.org> wrote: > > Hmm, if we would calculate with 200 cards we would have ~80 USD costs for them. > Maybe not the baddest thing. Let's wait to what conclusion we come here before > going ahead. A technical solution that let the user handle the registration on > it's own is still my favorit. Sadly we can't estimate how many subscribers we > will get. :) I don't know if you get a better price if you buy such a large amount of the SIM cards, but I would ask. One advantage of handing out SIM cards: You can play with authentication and encryption if you want to. The A3/A8 algorithm in the SIM cards seems to be different from COMP128-V1 (at least with the SIM I tested) so you cannot retrieve Ki. However you could run the authentication in advance and record a few challenge-reponse pairs and use them later. And if you take one Euro as deposit for the SIM, you might get them back or don't care if not. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Re: GSM license approval for HAR2009
by Dieter Spaar 22 Jul '09

22 Jul '09

Hello Stefan, On Wed, 22 Jul 2009 18:32:28 +0200, "Stefan Schmidt" <stefan(a)datenfreihafen.org> wrote: > > Hmm, another idea pops up into my mind right now. Any chance we can get a big > bunch of pre paid SIMs without money on the account? If we would get some 100s > of them we could prepare them in advance and just hand out to the people. Kai Muenz mentioned it on the list already, there are GSM SIMs available at http://www.dealextreme.com/details.dx/sku.16159. 10 pieces cost $US 3.94 including shipping. If you don't mind about a Chinese SIM Toolkit Menu which you can't read and also don't mind to remove a little bit of glue from some of the SIMs, they are fine for this purpose. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Re: Spectrum analysis shows strange carrier
by Dieter Spaar 21 Jul '09

21 Jul '09

Hello Philipp, On Mon, 20 Jul 2009 20:19:16 CEST, "Dieter Spaar" <spaar(a)mirider.augusta.de> wrote: > > Not sure what you are measuring on peak one and two, but channel 123 > should be 959.6 MHz, this is most certainly the third peak. There might > be small signals (e.g. from the oscillator of the BS-11) on other > frequencies, but they should be much smaller than the main signal. In the meantime I did check with my spectrum analyzer. There is indeed a signal coming from the BS-11, even if nothing else is connected to the BS-11 (no serial connection, no E1). The signal starts to be emitted after the firmware download is complete. I could measure the signal at 942.4 MHz, the level is about -42 dBm (cable connection from the spectrum analyzer to TRX0, low-quality cable). The signal strength does not depend on the power amplifier setting, I wonder where it comes from (some internal oscillator working at that frequency ?). The signal is not very strong, so it should not cause major trouble (besides disturbing a weak signal which might be there from an "official" source if you are close to the BS-11). Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Re: Spectrum analysis shows strange carrier
by Dieter Spaar 20 Jul '09

20 Jul '09

Hello Philipp, On Mon, 20 Jul 2009 18:39:47 +0200, "dexter" <zero-kelvin(a)gmx.de> wrote: > > We have a Toy-Spectrum-Analyser here, so i have measured the output of > our BS-11 when initalized with -f 123 > > http://www.root.runningserver.com/pub/openbsc_spektralanalyse.png > Not sure what you are measuring on peak one and two, but channel 123 should be 959.6 MHz, this is most certainly the third peak. There might be small signals (e.g. from the oscillator of the BS-11) on other frequencies, but they should be much smaller than the main signal. I don't know what the specification for a BTS allows as level for emitting on other frequencies, so I can't give you any numbers how strong those other signals can be. Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Spectrum analysis shows strange carrier
by dexter 20 Jul '09

20 Jul '09

Hi folks. We have a Toy-Spectrum-Analyser here, so i have measured the output of our BS-11 when initalized with -f 123 http://www.root.runningserver.com/pub/openbsc_spektralanalyse.png Why are there 2 carriers emitted by the BTS? I thought that openBSC uses only one TRX. I have verfied that the carrier must be emitted by the BTS. If i stop the BTS the carrier vanishes and the T-Mobile carrier comes through (much weaker, of cause) I have no explaination for this effect, can anyone give me a hint? regards Philipp

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mISDNdebugtool status
by Harald Welte 17 Jul '09

17 Jul '09

Hi Andreas, since youre experience with mISDN is much better than mine, can you comment on the status of mISDNdebugtool? As it seems, Eric is having some problems using it. Also, in current mISDNuser.git (socket branch), it doesn't compile since mISDNdebugtool.h is missing. What we're trying to do is to generate pcap files that we can throw at wireshark. Thanks in advance, -- - Harald Welte <laforge(a)gnumonks.org> http://gnumonks.org/ ============================================================================ We all know Linux is great...it does infinite loops in 5 seconds. -- Linus

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Re: CCCH
by Dieter Spaar 17 Jul '09

17 Jul '09

Hello Eric, On Thu, 16 Jul 2009 17:53:53 +0200, "Eric Cathelinaud" <e.cathelinaud(a)googlemail.com> wrote: > > Yes I would like to make the cell phone answer as fast as possible but > without the need of a user interaction. So I am trying to get RACH as fast > as possible and I think the paging function is the most suitable for this. A > RACH for each frame would be really nice. At least one RACH out of 2 frames, > then i can have at least 1 RACH per 10 ms. I don't think you have much influence on setting the paging reorganisation mode, this is done by the BTS when it detects that something has changed with paging (the BTS can detect it by looking for changes in the SYSTEM INFORMATION messages). I did a quick test with a nanoBTS 1800, if for example BS_PA_MFRMS is changed, the BTS will activate the paging reorganisation mode while switching the parameter. I can confirm that with the Nokia Network Monitor, it displays the page mode and indicates "paging reorganisation" for a short amount of time (about one second). You can try to constantly switch the SYSTEM INFORMATION data related to paging, but I don't know if this will help with what you want to do. Also please note that I have not tried it with the BS-11. Best regard, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Re: CCCH
by Dieter Spaar 16 Jul '09

16 Jul '09

Hello Eric, On Thu, 16 Jul 2009 15:44:21 +0200, "Eric Cathelinaud" <e.cathelinaud(a)googlemail.com> wrote: > > I don't know if the mobile phone will answer everytimes if i try to do a > paging on it for each successive frame. Or if he will answer the first time > and ignore the other paging requests after. Maybe you can explain what you want to achieve, this might help to give an answere. I initially thought you want to measure the standby time of the phone, this is why posted the information about the BS_PA_MFRMS parameter, it usually determines the standby time (if BS_PA_MFRMS is maximum, you usually get the longest standby time). But now it seem you want the phone to react as fast as possible on a paging request, but maybe I don't understand what you want to do. Best regards, Dieter PS: The calculation of the paging group is done by OpenBSC and not by the BTS. -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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Re: CCCH
by Dieter Spaar 16 Jul '09

16 Jul '09

Hello Eric, On Wed, 15 Jul 2009 11:00:14 +0200, "Eric Cathelinaud" <e.cathelinaud(a)googlemail.com> wrote: > > I was just thinking about performing a recursive paging in order to see how > much time I have until the battery of a mobile phone run out. > Does anyone know if the mobile phone answers at every paging or if it > doesn't "listen" all the time? I think it listens periodically. If anyone > can give me a clue, that would be appreciated. This is an excerpt from a posting to another mainling list, I just quote it because I don't want to repeat what I already wrote: > - The phone is in "idle" mode (no speech/data traffic) > and periodically receives the paging channel (PCH) to > find out if its being called. Further the phone measures > the signal strength of neighbor cells and every now > and then (not that frequent as the above actions) > receives the cell information in the broadcast common > control channel (BCCH) of the serving cell and of > at most six neighbor cells with the strongest signal. .... > - The time between receiving the PCH is determined by a > parameter of the serving cell (BS_PA_MFRMS, range 2 to 9). > Its measured in 51-multiframes until the PCH for the phone > repeats (if you want to know the details have a look at > the GSM specs ;-) . The length of a 51-multiframe is > 235.8 ms, this means the time between receiving the PCH > is in the range 471.9 ms to 2122.2 ms. In this time the > idle phone most of the time sleeps or receives the BCCH > of the serving cell or one of the neighbor cells with > the strongest signal (at most six). Best regards, Dieter -- Dieter Spaar, Germany spaar(a)mirider.augusta.de

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CCCH
by Eric Cathelinaud 15 Jul '09

15 Jul '09

2009/7/10 Harald Welte <laforge(a)gnumonks.org> On Thu, Jul 09, 2009 at 01:18:05PM +0200, Eric Cathelinaud wrote: > > Hi everybody > > > > I just would like to be sure that the paging is only sent on TS0 with > > OpenBSC, that is to say PCH (which is on CCCH) is only sent on TS0. > > I read that it could be sent on more time slots (TS2, TS4 and TS6 also) > in > > the GSM specifications. Is it the case in the soft or you just keep the > > normal multiplexage setting (TS0 only for CCCH+BCCH, 1 slot for dedicated > > channels and 6 slots for the traffic channels)? > > we only run one timeslot (TS0) for the CCCH (and thus the PCH). Using more > timeslots is only required in really large BTS with many TRX - not a case > we particularly care about right now. > > -- > - Harald Welte <laforge(a)gnumonks.org> > http://laforge.gnumonks.org/ > > ============================================================================ > "Privacy in residential applications is a desirable marketing option." > (ETSI EN 300 175-7 Ch. A6) > Ok thanks I was just thinking about performing a recursive paging in order to see how much time I have until the battery of a mobile phone run out. Does anyone know if the mobile phone answers at every paging or if it doesn't "listen" all the time? I think it listens periodically. If anyone can give me a clue, that would be appreciated. Eric Cathelinaud

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