While NACC was initially developed, it became clear there was need for a way to interact PCU<->BSC in order resolve ARFCN+BSIC into CGI-PS for later RIM usage. Hence, this resolution was first (until today) implemented using an out of bands RPC system using the CTRL interface, which required specific config to be written and matches in osmo-pcu and osmo-bsc VTY (ip+port of the CTRL interface to use). However, this has several shortcomings: * As explained above, specific configuration is required * Since recently, we do support BSC redundancy in osmo-bts. Hence the BTS may switch to a BSC other than first one. If that happened, that'd mean the CTRL interface would still point to the initially configured one, which may not be the same currently serving the PCU. During recent development of ANR related features, a similar need for PCU<->BSC was required, but this time it was decided to extend the IPA multiplex of the Abis OML connection to pass PCUIF messages, transparently forwarded to each side by the BTS. This has the advantage that connection PCU<->BTS is handled by BTS and both sides send messages transparently. Let's switch by default to using this new interface, while still maintaing the old way for a while (announcing them as deprecated) to avoid breaking existing deployments until they are upgraded to new versions of osmo-pcu and osmo-bsc. Related: SYS#4971 Change-Id: I6ad33c7ab10202840cf804dea9ba595978d0e920
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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
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/
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.
Discussions related to osmo-pcu are happening on the firstname.lastname@example.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
- 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
- Multi-BTS support not tested