OpenBSC January 2024

openbsc@lists.osmocom.org

8 participants
19 discussions

dynamic traffic channels
by Neels Hofmeyr 20 May '25

20 May '25

On Tue, Jun 28, 2016 at 10:05:28AM +0200, Harald Welte wrote: > [translated from german] > is it certain that we switch a channel to PDCH only when > gprs mode != none? A TS can be GSM_PCHAN_TCH_F_PDCH; those are the only ones for which we send a PDCH ACT message. We send a PDCH ACT message - during init (CHANNEL OML's state changed to enabled -> send PDCH ACT), - and upon channel release ack when pchan == GSM_PCHAN_TCH_F_PDCH. So the question is, when we receive a channel release ack, could that be the PDCH release and we switch PDCH right back on by accident? No, because we only receive a chan rel ack when the *TCH/F* is being released. That is because the PDCH release is initiated "internally" from the PDCH DEACT, and thus this condition in common/rsl.c rsl_tx_rf_rel_ack() catches on, which existed before dyn PDCH: if (lchan->rel_act_kind != LCHAN_REL_ACT_RSL) { LOGP(DRSL, LOGL_NOTICE, "%s not sending REL ACK\n", gsm_lchan_name(lchan)); return 0; } In rsl_rx_rf_chan_rel() the rel_act_kind is set to LCHAN_REL_ACT_RSL, but not in the rsl_rx_dyn_pdch(). This is analogous to the ip.access way -- the ip.access nanobts replies to a PDCH DEACT with a PDCH DEACT ACK and doesn't send a separate channel release ack. Maybe we could set rel_act_kind to some new LCHAN_REL_ACT_IPAC_DYN_PDCH for clarity? (But we shouldn't actually send a release ack, to stay compatible.) Even though it works as-is, we should indeed add another flag check: - We do check the flags that no ACT/DEACT is already pending; - And we do send a PDCH DEACT only if ts->flags & TS_F_PDCH_ACTIVE; - But we would send a PDCH ACT despite ts->flags & TS_F_PDCH_ACTIVE. This should never happen, but it would make sense to ensure that. ~Neels

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GSMTAP new version (3?)
by Mauro Levra 06 May '24

06 May '24

Dear Osmocom developers, In our project we have been using the gsmtap pseudo-header to store UMTS and LTE signalling traces in pcapng format. This is very efficient compared to our previous implementation based on DLT_USER, and thanks to the gsmtap dissector, it allows any *shark app to read our output file. When looking for the proper type and sub_type for NR signalling traces, I discovered they are not yet part of the standard. I found several threads of discussion about this, from about 2017 onwards, and I understand it is a matter of time and resources if the version 3 of GSMTAP has not been released. The most interesting feature I have read about is the ability to extend the header with a TLV approach. EARFCN, eNodeB-ID, PCI, are useful metadata we would like to add to our traces. In an ideal world, I would like things to be put in motion so that a new version of GSMTAP could see the light. More humbly, I ask you what kind of help is needed. Are you waiting for a draft specification? Are all requirements well known? I suppose that LTE and NR are not the main focus today for liboscmocore development, but there are many projects out there waiting for the GSMTAP format to be updated. Thanks! Mauro

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libosmocore/BSC/MSC: MO voice calls rejected from Siemens S11E (patch included)
by Lennart Müller 31 Jan '24

31 Jan '24

Hi, I had a problem placing MO GSM calls from a Siemens S11E: The calls were dropped immediately; Osmo-MSC reports "Cannot compose Channel Type from bearer capabilities" After investigating the SETUP request from the S11E, the phone does not use octet 3a (no extension bit set in IE 3). Wireshark decodes the radio channel requirement as "Full rate support only MS/fullrate speech version 1 supported", so I added a condition to the gsm48_ie.c function of libosmocore to include at least GSM FR in the list of available speech_ver in case octet 3 has no extension. Attached to this message are the Abis-IP PCAP traces of MO calls, and the patch for gsm48_ie.c. Regards, Lennart

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Problem while running NIB on Open Cellular Base sation
by Brackley Casinga 31 Jan '24

31 Jan '24

Hi, My name is Brackley Cassinga Form DRC, we run a community network called pamoja net where we offer gsm services using osmocom open source software and OC Base station. Recently I have tried to install another base station as the same installed but I could not find any resource guiding through all the steps to take to run NIB on a base station. I'm currently running Ubuntu and I will appreciate if you could guide me on the installation of BSC,hlr,MSC , in order to run a basic gsm network. Thank you. Regards -- *Ir Brackley heshima Casinga **Pacifique* *CEO and Founder of kwanzatechnologie* KwanzaTechnologies ,GlobalElectronics +243977265291 | +243977265291 | Pcassinga(a)gmail.com/ brackley(a)ensemblepourladifference.org www.kwantechnologies.jimdosite.com <http://www.kwantechnologies.com/> | Skype: Brackley cassinga <https://webapp.wisestamp.com/#> Av Semliki N 43

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Helping an Australian set up his own personal GSM/2G cell
by Mychaela Falconia 28 Jan '24

28 Jan '24

Hello Osmocom community, I have a contact in Australia who reached out to me with a desire to set up his own personal GSM/2G network. Australia is a nasty anti- retrotechnology country, even worse than USA, where all official 2G networks were shut down back in 2018. As most of you know, I run my own pirate-radio GSM cell in USA, and I tried reaching out to other Vintage Mobile Phone communities, promoting the idea that people can run their own networks using Osmocom CNI plus suitable hw plus my ThemWi add-ons for outside PSTN interconnection, and offering to teach others how to copy what I am doing. When I made the latter offer to the community, I was expecting people from other parts of USA - but right now the only person with an active interest is in Australia. I am currently teaching my Australian contact the "pure physics" aspects of running your own GSM network: what frequencies are usable for GSM, dB and dBm units of measurements, how to use a handheld spectrum analyzer etc. These are all "physics" topics that are independent of where one happens to be geopolitically. But there is another key aspect which I feel he needs to know, but which I won't be able to teach him: country-specific spectrum-political aspects. I know the spectrum-political landscape in USA: how FCC has divvied up PCS1900 and GSM850 bands (or B2 & B5 in modern parlance) between carriers, which spots in these bands are completely unused and thus reasonably safe to squat in, and how one can exploit the overlap between EGSM900 DL and USA ISM band to run a BTS with low probability of getting into trouble. But I have absolutely no such knowledge for any other country in the world, let alone one as remote and foreign to me as Australia. Is there anyone in this community who is based in Australia and knows this topic? I would greatly appreciate any advice from an AU-knowing person that I could pass to my GSM-enthusiast contact: out of the 4 frequency bands that are in-principle suitable for GSM, which is the safest one to squat in for a pirate operator, and which ARFCN range(s)? Obviously I will teach my contact that he needs to pick a spot where the spectrum analyzer shows nothing but noise floor, but just because a spot "looks blank" on an SA doesn't mean that the spot is safe to squat on, without knowing anything at all about the country's spectrum-political landscape... TIA, Mychaela

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Osmocom with limesdr Mini 2.0
by jheyrendt.ext＠orange.com 26 Jan '24

26 Jan '24

Dear all We have a questions for you, experts. Has anyone managed to get Osmocom with limesdr Mini 2.0 ? (USB) We have stability issues, so if someone has tried and can share configuration for osmocom-bsc and osmocom-trx-lms, it woud be great ! Many thanks in advance, Best regards

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Open Source Involvement
by Tanya P 24 Jan '24

24 Jan '24

Good Morning, My name is Tanya and was referred to this email regarding open source involvement. I am genuinely interested in sysmocom and am open to exploring various ways I can support your team. If there are any upcoming opportunities or specific areas where my skills could be of value in a volunteer capacity, I would be grateful for the chance to discuss them further. Please take a look at my GitHub profile: https://github.com/wonntann Thank you again for your consideration. I look forward to the possibility of contributing to sysmocom and will continue to follow your updates. Best, Tanya

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leave
by Roland Martinson 03 Jan '24

03 Jan '24

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TCP port numbers for vty/ctrl/etc of 3rd-party programs
by Mychaela Falconia 03 Jan '24

03 Jan '24

Hello Osmocom community, I have a question about TCP port number assignment for programs using libosmovty. Every Osmo-official server program gets official port number assignments listed in the wiki, in PDF manuals etc - so far, so good. But what about non-Osmo-official 3rd-party programs that wish to use common Osmocom libraries, including the vty facility? Suppose that an operator of an Osmocom-based cellular network needs to develop some additional programs to satisfy some operational need, and some of these additional programs are long-lived server processes for which an Osmocom-style vty interface would be very useful. But implementing such a telnet vty i/f requires a TCP port number... Has anyone thought about designating an official range of TCP port numbers which would be recommended for vty/ctrl/etc ports of processes that use Osmocom libraries and extend Osmocom CNI in various ways, but aren't official Osmocom projects? M~

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OpenBSC January 2024