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Status Report on Osmocom's 3G Support

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 GmbH (1), 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).

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 32c3 (2), 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_ss7 (3)).

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 Eurecom (4) 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 repositories (5).

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

Osmocom Berlin Meeting / 2015-12-09

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 ;)

More information can be found at OsmocomMeeting/Berlin

Osmocom Berlin User Group / 2015-11-11

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

Nov 11, 8pm @ CCC Berlin, Marienstr. 11, 10117 Berlin

There is no formal presentation this time, but

  • there will be SDR equipment, antenna and a working/tested setup of a gnuradio based MPT1327 decoder
  • 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
  • there will be Huawei Femtocells to play with
  • Harald would like to discuss OpenBSC website / documentation improvements

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 ;)

More information can be found at OsmocomMeeting/Berlin

  • Posted: 2015-11-09 00:35 (Updated: 2015-11-09 00:38)
  • Author: laforge
  • Categories: osmug
  • Comments (0)

Osmocom Berlin Meeting 2015-10-21

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

Oct 21, 8pm @ CCC Berlin, Marienstr. 11, 10117 Berlin

There is no formal presentation this time, but

  • there will be SDR equipment in case more people are interested to have a look at MPT1327 and/or Tetrapol signals that can be received in Berlin
  • Harald would like to discuss OpenBSC website / documentation improvements

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 ;)

More information can be found at OsmocomMeeting/Berlin

CANCELLED 2015-10-15 / Berlin: Presentation on OpenAirInterface

THIS EVENT HAS BEEN CANCELLED!

This is an announcement for an "irregular" Berlin Osmocom User Group event.

David Rupprecht of Ruhr-Uni Bochum has offered to give us a presentation sharing his experience in Running OpenAirInterface.

OpenAirInterface (http://openairinterface.eurecom.fr/) is a project of the Eurecom research institute in Sofia Antipoils / France. For many years they have been working towards an open source SDR LTE implementation.

The presentation will be held on

Oct 15, 8pm @ IN-Berlin, Lehrter Str. 53, 10557 Berlin

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 ;)

More information about the venue can be found at http://www.in-berlin.de/space/

  • Posted: 2015-10-03 20:33 (Updated: 2015-10-09 08:27)
  • Author: laforge
  • Categories: osmug
  • Comments (0)

Osmocom Berlin User Group / 2015-10-07

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

Oct 7, 8pm @ CCC Berlin, Marienstr. 11, 10117 Berlin

Harald will be presenting about the Iuh protocol stack (HNBAP,RUA,RANAP) of UMTS small cells / femtocells and his work towards implementing it as part of Osmocom.

Agenda:

  • 20:00h Welcome
  • 20:15h Presentation about Iuh / osmo-iuh
  • 21:00h Informal meeting / chatting

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 ;)

More information can be found at OsmoUserGroup/Berlin

  • Posted: 2015-10-03 17:57 (Updated: 2015-10-03 18:21)
  • Author: laforge
  • Categories: osmug
  • Comments (0)

OsmoDevCon from March 27 through March 30, 2015

OsmoDevCon? 2013-03-27 till 2013-03-30, Berlin

Dear fellow Osmcoom developers,

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

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 ​laforge@gnumonks.org 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 ​http://openbsc.osmocom.org/trac/wiki/OsmoDevCon2015

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

Best regards and happy hacking,

Harald

osmocom.org server outage

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 sysmocom.

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
  • noris.net for mailing the hard disks to Berlin
  • the community for their patience with the slow recovery process

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

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 laforge@gnumonks.org 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 http://openbsc.osmocom.org/trac/wiki/OsmoDevCon2013

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

Best regards and happy hacking,

Harald

Osmocom Berlin User Group / 2013-02-20

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 ;)

  • Posted: 2013-02-19 18:12 (Updated: 2013-02-19 18:13)
  • Author: dexter
  • Categories: (none)
  • Comments (0)

Osmocom Berlin User Group / 2013-02-06

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 ;)

  • Posted: 2013-02-03 20:54
  • Author: dexter
  • Categories: (none)
  • Comments (0)

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

After months of work by Ivan Kluchnikov and Andreas Eversberg, the Osmocom GPRS Packet Control Unit (PCU) 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 osmo-bts on the sysmocom sysmoBTS hardware, or with Fairwaves' branch of OpenBTS on hardware like the Ettus USRP family or UmTRX.

Osmocom Berlin User Group / 2013-01-23

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

January 23, 8pm @ CCC Berlin, Marienstr. 11, 10113 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 ;)

Osmocom Berlin User Group / 2013-01-09

Happy new year!

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

January 9, 8pm @ CCC Berlin, Marienstr. 11, 10113 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 ;)

  • Posted: 2013-01-07 13:17 (Updated: 2013-01-17 10:59)
  • Author: dexter
  • Categories: (none)
  • Comments (0)

Osmocom Berlin User Group / 2012-12-19

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

December 19, 8pm @ CCC Berlin, Marienstr. 11, 10113 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 ;)

  • Posted: 2012-12-18 09:16 (Updated: 2012-12-18 09:17)
  • Author: dexter
  • Categories: (none)
  • Comments (0)

Osmocom Berlin User Group / 2012-11-21

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

November 21, 8pm @ CCC Berlin, Marienstr. 11, 10113 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 ;)

However, there will be free Lebkuchen

  • Posted: 2012-11-19 10:25 (Updated: 2012-11-19 10:27)
  • Author: laforge
  • Categories: osmug
  • Comments (0)

Osmocom Berlin User Group / 2012-11-07

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

November 07, 8pm @ CCC Berlin, Marienstr. 11, 10113 Berlin

There is no formal presentation scheduled for this meeting. Holger might present about (regression/unit) testing inside the Osmocom project.

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 ;)

Osmocom Berlin User Group / 2012-09-19

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

September 19, 8pm @ CCC Berlin, Marienstr. 11, 10113 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 ;)

Osmocom Berlin User Group / 2012-09-05

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

September 05, 8pm @ CCC Berlin, Marienstr. 11, 10113 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 ;)

Osmocom Berlin User Group / 2012-08-22

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

August 22, 8pm @ CCC Berlin, Marienstr. 11, 10113 Berlin

There is no formal presentation scheduled for this meeting. However, updates will be provided on various current developments, such as

  • Progress on the CC32RS512 smart card (osmo-cos)
  • Possibly: Status of current attempts to get CSD implemented in OpenBSC

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 ;)