Osmocom Packet control Unit (PCU): Network-side GPRS (RLC/MAC); BTS- or BSC-colocated https://osmocom.org/projects/osmopcu
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Minh-Quang Nguyen 1f18909335 EDGE: Fix UL link adaptation.
We have seen that UL MCS5- MCS9 link adaptation has not been implemented in current PCU implementation.
If the MS slowly moves far away from the BTS, the UL MCS will always stick at MCS9 no matter UL link quality values leading to poor data service experience.
The UL MCS is expected to adapt from MCS9 -> MCSx due to bad UL quality.

Below PCU traces indicate that UL MCS is quickly increasing to MCS9 (max MCS 9 was used in this test) and it never changes to other UL MCS due zero thresholds.

<0004> gprs_ms.cpp:670 MS (IMSI ): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-6 -> MCS-7
<0004> gprs_ms.cpp:670 MS (IMSI 000): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-7 -> MCS-8
<0004> gprs_ms.cpp:670 MS (IMSI 000): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-8 -> MCS-9

Change-Id: I9272c337ad6399da4a47cc6e2736e25f24e099d8
2017-08-18 18:09:24 +00:00
contrib jenkins.sh: Proper error message if local environment isn't set up 2017-07-10 14:01:07 +00:00
debian Add pkg-config file 2017-03-09 12:17:35 +01:00
examples Revert "pcu: Improve default config" 2015-11-30 12:11:48 +01:00
include Add pcu-socket vty config 2017-08-09 12:17:39 +02:00
src EDGE: Fix UL link adaptation. 2017-08-18 18:09:24 +00:00
tests Simplify polling troubleshooting 2017-08-14 15:19:08 +00:00
.gitignore Ignore test binaries using mask 2017-07-10 10:49:02 +02:00
.gitreview add .gitreview 2016-05-19 06:39:45 +00:00
COPYING import GPLv2 license text to this project 2012-07-22 22:05:44 +02:00
Makefile.am Update README file with general project info and use Markdown 2017-03-17 17:24:55 +01:00
README.md README: Clarify that fixed allocations have been revmoved from 3GPP specs 2017-07-29 22:15:02 +02:00
TODO TODO: Update the todolist with some musings... 2014-01-16 10:11:57 +01:00
configure.ac lc15: further fixes regarding --with-litecell15 2017-06-11 11:40:18 +02:00
git-version-gen Add auto-foo (partial cleanup, master makefile/configure.ac 2012-06-14 21:05:44 +08:00
osmo-pcu.pc.in Add pkg-config file 2017-03-09 12:17:35 +01:00
osmoappdesc.py Added conditional python-based tests for VTY/config handling 2013-04-06 11:00:20 +02:00


osmo-pcu - Osmocom Packet Control Unit

This repository contains a C/C++-language implementation of a GPRS Packet Control Unit, as specified by ETSI/3GPP. It is part of the Osmocom Open Source Mobile Communications project.

The Packet Control Unit is terminating the Layer 2 (RLC/MAC) of the GPRS radio interface and adapting it to the Gb Interface (BSSGP+NS Protocol) towards the SGSN.

The PCU interfaces with the physical layer of the radio interface. OsmoPCU is typically used co-located with the BTS, specifically OsmoBTS. For legacy BTSs that run proprietary sotware without an interface to OsmoPCU, you may also co-locate it with the BSC, specifically OsmoBSC


The official homepage of the project is https://osmocom.org/projects/osmopcu/wiki/OsmoPCU

GIT Repository

You can clone from the official osmo-pcu.git repository using

git clone git://git.osmocom.org/osmo-pcu.git

There is a cgit interface at http://git.osmocom.org/osmo-pcu/


We provide a user manual as well as a vty reference manual

Please note that a lot of the PCU configuration actually happens inside the BSC, which passes this configuration via A-bis OML to the BTS, which then in turn passes it via the PCU socket into OsmoPCU.

Mailing List

Discussions related to osmo-pcu are happening on the osmocom-net-gprs@lists.osmocom.org mailing list, please see https://lists.osmocom.org/mailman/listinfo/osmocom-net-gprs for subscription options and the list archive.

Please observe the Osmocom Mailing List Rules when posting.


Our coding standards are described at https://osmocom.org/projects/cellular-infrastructure/wiki/Coding_standards

We us a gerrit based patch submission/review process for managing contributions. Please see https://osmocom.org/projects/cellular-infrastructure/wiki/Gerrit for more details

The current patch queue for osmo-pcu can be seen at https://gerrit.osmocom.org/#/q/project:osmo-pcu+status:open

Current limitations

  • No PFC support
  • No fixed allocation support (was removed from 3GPP Rel >= 5 anyway)
  • No extended dynamic allocation support
  • No unacknowledged mode operation
  • Only single slot assignment on uplink direction
  • No half-duplex class support (only semi-duplex)
  • No TA loop
  • No power loop