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OpenBSC: OsmoDevCon from March 27 through March 30, 2015

Added by laforge about 1 year ago

Dear fellow Osmcoom developers,

it is my pleasure to finally announce the date + venue of OsmoDevCon2015:

  • Date: March 27 through March 30, 2015
  • Place: IN-Berlin, Lehrter Str. 53, Berlin

Like last year, this is an event for developers of the various Osmocom proejects. Reservation and confirmation of reservation is required.

The event is free of charge. The Room is made available by ​IN-Berlin e.V., an Internet related non-profit organization. Lunch catering will be sponsored (so far by sysmocom GmbH, but if any other sponsors come up, we are happy to share the cost).

So all you have to cover is your own travel + accomodation costs, as well as breakfast and dinner. If you are an active developer and cannot afford travel/accomodation, please let me know and I'll see if we can do something about it.

If you would like to attend, please send a message to ​​ applying for registration of the event. The registration deadline is February 20, i.e. one week from now.

There is no detailed schedule of talks yet. I will start a separate discussion suggesting / collecting topics in the next couple of days.

More information is (and will be made) available at OsmoDevCon2015

Further discussion regarding the event should be directed at the mailing list, to avoid cross-posting over the various project-specific lists.

Best regards and happy hacking,

Harald

OpenBSC: Status Report on Osmocom's 3G Support

Added by laforge about 1 year ago

3G is dead, you may think. From the perspective of large scale operators, that may well be the case, but this is precisely the reason why Open Source support for 3G is becoming increasingly interesting: when the focus for earning money shifts towards LTE infrastructure, the threshold for setting up 3G networks is becoming easier to surpass for everyone else.

We are implementing Iuh support in the Osmocom stack, mostly carried out by employees of sysmocom GmbH1, with highly appreciated (yet undisclosed) external backing.

Iu support in Osmocom will allow using a femto-cell aka hNodeB as BTS, thus enabling UMTS voice (IuCS) and data (IuPS) connectivity using FOSS software from the core network right up to the femto-cell's ethernet jack.

Here is an ASCII art overview of our current aim:

        +------------+           +--------+          +----------+
 UE <-->| hNodeB     |<--Iuh---->| HNB-GW |<--IuCS-->| OsmoCSCN |
 UE <-->| femto cell |     ...-->|        |    ...-->|          |
        |            |           |        |          +----------+
        +------------+<--GTP-U   |        |
                              \  |        |          +------+           +------+
                              |  |        |<--IuPS-->| SGSN |<--GTP-C-->| GGSN |
                              |  +--------+    ...-->|      |   GTP-U-->|      |
                              |                      +------+  /        +------+
                              \_______________________________/

                      Iuh                         IuCS/IuPS

NAS                   +----+----+                 +----+----+
Non-Access Stratum    | CC | MM |                 | CC | MM |
- - - - - - - - - - - +----+----+-------+         +----+----+
                      | RANAP   |       |    H    | RANAP   |
Access Stratum        +---------+ HNBAP |    N    +---------+ - - SCCP USER SAP
                      | RUA     |       |    B    | SUA     |  \
                      +---------+-------+    -    +---------+  |
                      |        SCTP     |    G    | SCTP    |  } SIGTRAN
                      +-----------------+    W    +---------+  |
                      |        IP       |         | IP      |  /
                      +-----------------+         +---------+

UE (User Endpoint) MS (Mobile Subscriber) mobile device
CSCN (Circuit Switched Core Network) == OsmoNITB without BSC
(Source: ​http://git.osmocom.org/osmo-iuh/tree/doc/protocols_around_hnbgw.txt )

3G Data Status

The best news first: in our lab, Daniel has successfully established the first functional UMTS data link!

In other words, the two GTP paths

hNodeB --Iuh--> HNB-GW --IuPS--> SGSN --GTP-C--> GGSN
hNodeB --GTP-U--> GGSN
are already functional in a basic fashion. To test it, you would need to checkout various branches in various git repositories. These shall soon be merged to the respective master branches, but currently, that would be:

  • libasn1c: master
  • asn1c: aper-prefix
  • libosmocore: master
  • libosmo-netif: sysmocom/sctp
  • libosmo-sccp: laforge/wip
  • osmo-iuh: master
  • openbsc: daniel/gprs-iu

3G Voice Status

The voice link (IuCS) still needs some work before even the attempt of a location update will make sense. The point here is that previously, OsmoNITB would combine the roles of BSC with the MSC and further core network components. For Iuh, though, the BSC role is actually embedded in the hNodeB, and thus we are aiming to split the BSC part off of OsmoNITB.

The result will be called OsmoCSCN, CSCN meaning Circuit-Switched-Core-Network, which lives in openbsc.git/openbsc/src/osmo-cscn/ (branch sysmocom/cscn).

NOTE from the future: OsmoCSCN has since been renamed to OsmoMSC!

OsmoCSCN comprises of "only" the MSC and further CN components. It will feature an IuCS interface, as well as, eventually, a proper A-interface towards 2G BSCs, thus obsoleting the OsmoNITB at some point.

Implementing OsmoCSCN is mostly my task, and after sinking some time into training my eye on the fine line between BSC and MSC, I've finally started actual development with the dawn of 2016.

3G in a Nutshell

Let me illustrate some details of the Iu interfaces. The following is basically Harald's 3G talk at the 32c32, but with the sheer abundance of complexity it can't hurt to read it in prose.

HNB-GW

The HNB-GW, i.e. the HomeNodeB Gateway, merely reads the CN-DomainIndicator from the RUA layer, which says whether the frame is for voice or data comms (IuCS or IuPS). It then sends the actual RANAP payload either to the OsmoCSCN or the OsmoSGSN. The HNB-GW is implemented in osmo-iuh/src/hnbgw.c, compiling as osmo-hnbgw, and is (mostly?) complete.

An interesting factoid is that for an hNodeB, the GTP-Control handshaking goes via the HNB-GW, while the packet user data actually goes directly to/from the hNodeB and the GGSN.

HNBAP

HNBAP is merely the protocol employed to register an hNodeB with the HomeNodeB Gateway. After HNBAP is done, the hNodeB sends RANAP-over-RUA, which the HNB-GW happily passes on to the proper consumers.

SIGTRAN

Typically, the IuCS and IuPS interfaces would talk this layering of protocols:

  CC/MM
  RANAP
  SCCP  <--- note
  M3UA  <--- note
  SCTP
  IP

We do have SCCP support in Osmocom, but so far only for "connectionless" messages (like your standard UDP datagrams). Iu now adds the need for establishing and tearing down connections (like TCP).

However, since SUA does the same as SCCP-over-M3UA and is simpler to implement, our HNB-GW talks SUA towards IuCS and IuPS:

  CC/MM
  RANAP
  SUA   <--- note
  SCTP
  IP

To support third-party MSC and SGSN components, we would either add SCCP-over-M3UA capability, or simply use an external signalling gateway that supports both M3UA and SUA (should be possible e.g. with osmo_ss73).

Various SIGTRAN implementations:

                IuCS/IuPS
                  usual
                   |     simplest
                   |       |
                   v       v
  +------+------+------+-----+
  | SCCP | SCCP |      |     |
  +------+------+ SCCP |     |
  | MTP3 | MTP3 |      |     |
  +------+------+------+ SUA |
  | MTP2 |      |      |     |
  +------+ M2UA | M3UA |     |
  | M2PA |      |      |     |
  +------+------+------+-----+
  |           SCTP           |
  +--------------------------+
  |            IP            |
  +--------------------------+

ASN1 Convolutions

RANAP, RUA and HNBAP, which make up the Iuh interface, are ASN1 encoded. Fair enough, but their ASN1 encoding uses APER, and heavily employs Information Object Classes (which basically means it wraps ASN1 encoded binary data in ASN1 IEs, with several levels of depth). In consequence, the libre asn1c compiler as-is unfortunately is not capable of generating de-/encoders for UMTS. The proprietary ffasn1c is capable of that, and we could publish the ffasn1c generated code without licensing problems, but we'd highly prefer to empower the FOSS community with the ability to modify and fix the ASN1 de-/encoders independently of proprietary software.

The great news is that Eurecom4 has worked on supporting both APER and the nested ASN1 structures ("Information Object Classes") in asn1c, and we are able to use their solutions in a FOSS way. With some fixes added, we have both their APER support and their pythonic solution for nested ASN1 available in Osmocom's libasn1c and asn1c git repositories5.

Another problem with the Iuh ASN1 is that various type names are identical across RANAP, RUA and HNBAP, while their encodings differ. This causes type name collisions in the code generated by asn1c, hence we have added prefixing support to our version of asn1c. This simply means that each RANAP-related type name or function begins with "ranap_", and RUA names begin with "rua_", thus avoiding any and all name collisions between those protocols. See osmo-iuh/include/osmocom/ranap/ and ../rua/.

It could be more beautiful, but the bottom line is that we now have fully free/libre support for Iuh ASN1 encodings. Cheers!

Conclusion

Osmocom is on a clear trajectory towards full 3G support, empowering remote communities and small to medium businesses worldwide. Work is ongoing, but the really hard problems have already been solved. Stay tuned!

External References

1 ​http://www.sysmocom.de

2 ​https://media.ccc.de/v/32c3-7412-running_your_own_3g_3_5g_network

3 ​http://git.osmocom.org/erlang/osmo_ss7

4 ​http://www.eurecom.fr

5 See ​http://git.osmocom.org/libasn1c/ and ​http://git.osmocom.org/asn1c/log/?h=aper-prefix

OpenBSC: Osmocom Berlin Meeting / 2015-12-09

Added by laforge about 1 year ago

This is the announcement for the re-incarnation of our bi-weekly OsmocomMeeting/Berlin meeting.

Dec 09, 8pm @ CCC Berlin, Marienstr. 11, 10117 Berlin

There is no formal presentation this time, but

  • there will be SIMtrace equipment in case somebody wants to play with it
  • there will be a sysmoBTS with OsmoBTS, OsmoPCU, OsmoNITB, OsmoSGSN and OpenGGSN if somebody wants to play with it
  • The meeting is open to anyone interested in mobile communications. You do not have to be involved with the Osmocom projects in order to attend. Anyone interested in mobile communications protocols is welcome.

If you are interested to show up, feel free to do so. The meeting is "free as in free beer", despite no actual free beer being around ;)

OsmocomGMR: Osmo-GMR now implements voice codec decoder

Added by tnt about 3 years ago

GMR-1 uses an undocumented codec in the AMBE family and as such Osmo-GMR didn't have any implementation of it and converting TCH3 frames to actual audio wasn't possible.

Now, after quite a bit of effort to figure things out, I'm pleased to announce that an open-source decoder is available. It's not perfect and doesn't match the quality of the official decoder but it does produce intelligible voice and will have to do for now.

It's currently available in a separate 'sylvain/codec' branch in the git but should be merged into master soon after a last review of the code.

OpenBSC: osmocom.org server outage

Added by laforge almost 4 years ago

For about one week from March 20, 2013 on most of the osmocom.org severs and services have been offline due to a hardware failure in the physical machine that was hosting all the virtual machines related to the project.

As I was on extensive business related travel, I couldn't go to the data center and take care of fixing the problem myself. So we had the hard disks sent to my home in Berlin, obtain a machine that has the neccessary SCA-80 connector for the old-fashioned enterprise SCSI hard disks and then start recovery by means of an old backup in the data center + rsync'ing the changes via my slow DSL uplink.

The good news is: Everything is up and running again on different hardware, and there is no data loss as the hard disk was fully intact.

In the coming weeks, we will migrate the various virtual machines over to a new (rented) physical machine, sponsored by http://​sysmocom.de/

I'd like to thank

  • zecke for providing emergency recovery for the git server
  • roh for providing an old Sun v20z to mount + read the SCA drives
    ​* http://noris.net/ for mailing the hard disks to Berlin
  • the community for their patience with the slow recovery process

OpenBSC: Osmocom Berlin User Group / 2013-02-06

Added by laforge almost 4 years ago

This is the announcement for the latest incarnation of our bi-weekly Osmocom Berlin meeting.

Feb 6, 8pm @ CCC Berlin, Marienstr. 11, 10117 Berlin

There is no formal presentation scheduled for this meeting. However, we'll have a progress report + demonstration of current osmo-pcu.

If you are interested to show up, feel free to do so. The meeting is free as in "free beer", despite no actual free beer being around ;)

OpenBSC: OsmoDevCon 2013-04-04 till 2013-04-07, Berlin

Added by laforge almost 4 years ago

Dear fellow Osmcoom developers,

it is my pleasure to finally announce the date + venue of OsmoDevCon2013:

  • Date: April 04 through April 07, 2013
  • Place: IN-Berlin, Lehrter Str. 53, Berlin

Like last year, this is an event for developers of the various Osmocom proejects. Reservation and confirmation of reservation is required.

The event is free of charge. The Room is made available by ​IN-Berlin e.V., an Internet related non-profit organization. Lunch catering will be sponsored (so far by sysmocom GmbH, but if any other sponsors come up, we are happy to share the cost).

So all you have to cover is your own travel + accomodation costs, as well as breakfast and dinner. If you are an active developer and cannot afford travel/accomodation, please let me know and I'll see if we can do something about it.

If you would like to attend, please send a message to ​ applying for registration of the event. The registration deadline is March 5, i.e. one week from now.

There is no detailed schedule of talks yet. I will start a separate discussion suggesting / collecting topics in the next couple of days.

More information is (and will be made) available at OsmoDevCon2013

Further discussion regarding the event should be directed at the mailing list, to avoid cross-posting over the various project-specific lists.

Best regards and happy hacking,
Harald

OpenBSC: Osmocom Berlin User Group / 2013-02-20

Added by laforge about 4 years ago

This is the announcement for the latest incarnation of our bi-weekly Osmocom Berlin meeting.

Feb 20, 8pm @ CCC Berlin, Marienstr. 11, 10117 Berlin

There is no formal presentation scheduled for this meeting.

If you are interested to show up, feel free to do so. The meeting is free as in "free beer", despite no actual free beer being around ;)

OpenBSC: osmo-pcu (GPRS Packet Control Unit) v0.1 released

Added by laforge about 4 years ago

After months of work by Ivan Kluchnikov and Andreas Eversberg, the Osmocom GPRS Packet Control Unit (OsmoPCU) has finally reached a point where it makes sense to release a first version: v0.1

There are still a number of limitations and shortcomings, most of which should be indicated in the wiki at osmo-pcu. However, even without hand-over, timing advance loop, power control loop or dynamic link adaption of the coding scheme, it is already a useful implementation for lab-type setups and small, indoor real-world deployments.

osmo-pcu can be used either with OsmoBTS on the sysmocom sysmoBTS hardware, or with Fairwaves' branch of OpenBTS on hardware like the Ettus USRP family or UmTRX.

(21-30/65)

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