Robert Schmidt
7a298e73cd
This commit repairs the reestablishment after the introduction of the CU UE ID in the CU, different from the DU UE ID. Now, the CU uses an identifier different from the RNTI, used in the MAC, to refer to UEs. To repair the reestablishment, a number of changes needed to be introduced: - Handle old_gNB_DU_UE_id in MAC The MAC handles the old_gNB_DU_UE_id field in the DL RRC Message. The commit adds encoding/decoding of the field. The MAC will drop the old UE, but retain the CellGroup of the corresponding UE(!). Because a UE releases the spCellGroup on reestablishment, the MAC does the same; it needs to reapply the old configuration after a reconfiguration. For the latter, introduce new variables to keep a "future" CellGroupConfig to be applied (reconfigCellGroup) and a flag (expect_reconfiguration) that applies the CellGroupConfig if a DL RRC Message transfer on DCCH, which is assumed to be the reconfiguration. - Add RNTI change in RLC The RLC needs to reuse the old UE context. Hence, we simply change the RNTI in the old context, and delete the new one. - No PDCP UE ID change The previous implementation of the PDCP used the RNTI; hence, the ID needed to be switch (as above for the RLC). Since the PDCP now also uses the CU UE ID, no identifier change is needed, and we remove all corresponding code. - No MAC modifications/update from CU As foreseen by the spec, the CU does not modify or change the cellGroupConfig in the RRC during reestablishment. This change will be generalized in the future to all of the RRC. Also, the nr_rrc_mac_remove_ue() function has been removed: the MAC handles any UE changes autonomeously, without being triggered from the RRC explicitly. - Remove reestablish_rnti_map The RRC does not use RNTIs for UE identification. Hence, a reestablish_rnti_map to link two UEs to each other is not necessary anymore.
OpenAirInterface License
It is distributed under OAI Public License V1.1.
The license information is distributed under LICENSE file in the same directory.
Please see NOTICE file for third party software that is included in the sources.
Where to Start
Not all information is available in a central place, and information for specific sub-systems might be available in the corresponding sub-directories. To find all READMEs, this command might be handy:
find . -iname "readme*"
RAN repository structure
The OpenAirInterface (OAI) software is composed of the following parts:
openairinterface5g
├── charts
├── ci-scripts : Meta-scripts used by the OSA CI process. Contains also configuration files used day-to-day by CI.
├── CMakeLists.txt : Top-level CMakeLists.txt for building
├── cmake_targets : Build utilities to compile (simulation, emulation and real-time platforms), and generated build files.
├── common : Some common OAI utilities, some other tools can be found at openair2/UTILS.
├── doc : Documentation
├── docker : Dockerfiles to build for Ubuntu and RHEL
├── executables : Top-level executable source files (gNB, eNB, ...)
├── maketags : Script to generate emacs tags.
├── nfapi : (n)FAPI code for MAC-PHY interface
├── openair1 : 3GPP LTE Rel-10/12 PHY layer / 3GPP NR Rel-15 layer. A local Readme file provides more details.
├── openair2 : 3GPP LTE Rel-10 RLC/MAC/PDCP/RRC/X2AP + LTE Rel-14 M2AP implementation. Also 3GPP NR Rel-15 RLC/MAC/PDCP/RRC/X2AP.
├── openair3 : 3GPP LTE Rel10 for S1AP, NAS GTPV1-U for both ENB and UE.
├── openshift : OpenShift helm charts for some deployment options of OAI
├── radio : Drivers for various radios such as USRP, AW2S, RFsim, ...
└── targets : Some configuration files; only historical relevance, and might be deleted in the future