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Handover tutorial: fix minor issues and add same-machine setup guidance

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- Update opening statement to reflect both F1 (intra-gNB) and N2 (inter-gNB) handover support
- Fix grammar error: 'either by by decision' -> 'either a decision'
- Standardize naming: 'gNB PCI1' -> 'gNB-PCI1'
- Fix typo: 'neighbor call' -> 'neighbor cell'
- Remove --sa flag from N2 handover target gNB command for consistency
- Add network configuration notes for same-machine setups:
  * IP address assignment instructions to avoid network conflicts
  * Target gNB command options for proper network interface configuration
This commit is contained in:
Guido Casati
2025-10-01 11:36:22 +02:00
parent dcd7ee711b
commit dcb10ffc94
1 changed files with 19 additions and 6 deletions
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doc/handover-tutorial.md
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@@ -1,5 +1,5 @@
This tutorial explains how to perform handovers. For the moment, only F1 This tutorial explains how to perform handovers. It covers both F1 handovers
handovers are supported. (intra-gNB, within a single gNB between DUs) and N2 handovers (inter-gNB).
[[_TOC_]] [[_TOC_]]
@@ -370,10 +370,16 @@ We assume:
* Two independent gNBs connected to the same 5GC via N2 interface. * Two independent gNBs connected to the same 5GC via N2 interface.
* A UE initially connected to gNB-PCI0, which will be handed over to gNB-PCI1. * A UE initially connected to gNB-PCI0, which will be handed over to gNB-PCI1.
* Handover is triggered by either by decision based measurement event (e.g. A3) or telnet command. * Handover is triggered by either a decision based measurement event (e.g. A3) or telnet command.
## Steps to run N2 handover with OAI UE ## Steps to run N2 handover with OAI UE
**Note for same-machine setup:** When running both gNBs on the same machine, you need to assign a unique IP address to the second gNB to avoid network conflicts. For example:
```sh
sudo ip addr add 192.168.71.180/24 dev rfsim5g-public
```
1. Similarly to F1 handover, UE does not support any measurement reporting and handover is triggered by 1. Similarly to F1 handover, UE does not support any measurement reporting and handover is triggered by
telnet command. Therefore, ensure that both gNBs and UE are built with telnet support: telnet command. Therefore, ensure that both gNBs and UE are built with telnet support:
@@ -397,10 +403,17 @@ sudo ./nr-uesoftmodem -r 106 --numerology 1 --band 78 -C 3619200000 --rfsim --ui
Ensure the UE successfully registers with the network. Ensure the UE successfully registers with the network.
4. Start the target gNB (gNB PCI1) e.g. 4. Start the target gNB (gNB-PCI1) e.g.
```sh ```sh
sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band78.fr1.106PRB.pci1.rfsim.conf --sa --rfsim --telnetsrv --telnetsrv.shrmod ci --gNBs.[0].min_rxtxtime 6 --rfsimulator.serveraddr 127.0.0.1 sudo ./nr-softmodem -O ../../../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band78.fr1.106PRB.pci1.rfsim.conf --rfsim --telnetsrv --telnetsrv.shrmod ci --gNBs.[0].min_rxtxtime 6 --rfsimulator.serveraddr 127.0.0.1
```
**Note for same-machine setup:** When running both gNBs on the same machine, add the following network interface options to the target gNB command, e.g.:
```sh
--gNBs.[0].NETWORK_INTERFACES.GNB_IPV4_ADDRESS_FOR_NG_AMF 192.168.71.180
--gNBs.[0].NETWORK_INTERFACES.GNB_IPV4_ADDRESS_FOR_NGU 192.168.71.180
``` ```
5. Trigger the N2 handover, e.g. 5. Trigger the N2 handover, e.g.
@@ -410,7 +423,7 @@ From gNB-PCI0, trigger handover on target gNB with PCI 1 for UE ID 1:
```sh ```sh
echo ci trigger_n2_ho 1,1 | nc 127.0.0.1 9090 && echo echo ci trigger_n2_ho 1,1 | nc 127.0.0.1 9090 && echo
``` ```
where the input parameters correspond to the PCI of the neighbor call and the RRC ID of the UE. where the input parameters correspond to the PCI of the neighbor cell and the RRC ID of the UE.
This will initiate the N2 handover on the source gNB. This will initiate the N2 handover on the source gNB.