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# The F1 interface
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<table style="border-collapse: collapse; border: none;">
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<tr style="border-collapse: collapse; border: none;">
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<td style="border-collapse: collapse; border: none;">
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<a href="http://www.openairinterface.org/">
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<img src="images/oai_final_logo.png" alt="" border=3 height=50 width=150>
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</img>
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</a>
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</td>
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<td style="border-collapse: collapse; border: none; vertical-align: center;">
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<b><font size = "5">The F1 Interface</font></b>
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</td>
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</tr>
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</table>
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The F1 interface is the functional split of 3GPP between the CU (centralized
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unit: PDCP, RRC, SDAP) and the DU (distributed unit: RLC, MAC, PHY). It is
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... | ... | @@ -6,7 +18,7 @@ standardized in TS 38.470 - 38.473 for 5G NR. Note that though there will be |
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the V1 interface destined for LTE, OAI implements the F1 interface in the LTE
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modem.
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The code is merged into `develop`.
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The code is merged into `develop` and fully tested in FDD mode starting tag `2019.w17`.
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# Control plane status (F1-C)
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... | ... | @@ -22,9 +34,9 @@ The following messages are currently implemented: |
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* UL/DL RRC Message Transfer
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* F1 UE Context Release Request/Command/Complete
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All other messages can be assumed to *not* be implemented:
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All other messages can be assumed to **not** be implemented:
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* F1 UE Context Setup Request is *not* implemented. Instead, it is somewhat
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* F1 UE Context Setup Request is **not** implemented. Instead, it is somewhat
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transparently handled through UL/DL RRC message transfers which set up the
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RLC etc.
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* All System Information messages
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... | ... | @@ -34,6 +46,7 @@ All other messages can be assumed to *not* be implemented: |
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Notes:
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* Tested up to four UEs
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* At time of writing, the CU **SHALL** be started before the DU
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* The CU can continue to run once the DU stops and does not need to be
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restarted (e.g. CN connections can remain intact)
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... | ... | @@ -55,14 +68,27 @@ standard-compliant GTP-U implementation lter. |
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# Usage
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Working F1 configuration files: [`cu.lte.conf`](f1-sample-conf/cu.lte.conf),
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[`du.lte.band7.conf`](f1-sample-conf/du.lte.band7.conf)
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## Working F1 configuration files ##
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Look into the [CI configuration folder](https://gitlab.eurecom.fr/oai/openairinterface5g/tree/develop/ci-scripts/conf_files):
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CU FDD files: for example [CU-FDD-5MHz](https://gitlab.eurecom.fr/oai/openairinterface5g/blob/develop/ci-scripts/conf_files/cu.band7.tm1.25PRB.conf)
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DU FDD files: for example [DU-FDD-5MHz](https://gitlab.eurecom.fr/oai/openairinterface5g/blob/develop/ci-scripts/conf_files/du.band7.tm1.25PRB.usrpb210.conf)
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Adapt the `CI_ENB_IP_ADDR` and `CI_MME_IP_ADDR` IP address markers to your system
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The CI configuration files are set for CU/DU to communicate through the loopback interface on the same server.
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If you run on different servers, vm or containers, adapt the `local_(s/n)_if_name` interface name, `remote_(s/n)_address` and `local_(s/n)_address` IP addresses accordingly.
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## Build and Run ##
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Build using the `build_oai` script as normal. Support for F1AP will be
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installed. Then, the same lte-softmodem executable is used to start CU and DU,
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subject toconfiguration parameters, i.e. start your EPC as normal, then run
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one instanceof the lte-softmodem as [CU](f1-sample-conf/cu.lte.conf) and one
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as [DU](f1-sample-conf/du.lte.band7.conf). The basic structure for both files
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one instanceof the lte-softmodem as **CU** and one
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as **DU**. The basic structure for both files
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is unchanged; notable differences to a monolithic deployment are the
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following:
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... | ... | |