maki/openairinterface5g
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

update description how to run NTN scenarios in RUNMODEM.md

Browse Source
This commit is contained in:
Thomas Schlichter
2025-02-14 17:03:56 +00:00
parent cf0a1d6db4
commit acac0b21bf
1 changed files with 62 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files
doc/RUNMODEM.md
+62 -16
View File
@@ -221,15 +221,49 @@ Or by providing this the the command line parameters:
### gNB
The main parameter to cope with the large NTN propagation delay is the cellSpecificKoffset.
This parameter is the scheduling offset used for the timing relationships that are modified for NTN (see TS 38.213).
The main parameters to cope with the large NTN propagation delay are cellSpecificKoffset, ta-Common, ta-CommonDrift and the ephemeris data (satellite position and velocity vectors).
The parameter `cellSpecificKoffset_r17` is the scheduling offset used for the timing relationships that are modified for NTN (see TS 38.213).
The unit of the field Koffset is number of slots for a given subcarrier spacing of 15 kHz.
This parameter can be provided to the gNB in the conf file as `cellSpecificKoffset_r17` in the section `servingCellConfigCommon`.
The parameter `ta-Common-r17` is used to provide the propagation delay between the reference point (at the gNB) and the satellite.
The granularity of ta-Common is 4.072 × 10^(-3) µs. Values are given in unit of corresponding granularity.
The parameter `ta-CommonDrift-r17` indicates the drift rate of the common TA.
The granularity of ta-CommonDrift is 0.2 × 10^(-3) µs/s. Values are given in unit of corresponding granularity.
The satellite position and velocity vartors are provided using the following parameters:
`positionX-r17`, `positionY-r17`, `positionZ-r17`:
X, Y, Z coordinate of satellite position state vector in ECEF. Unit is meter.
Step of 1.3 m. Actual value = field value * 1.3.
`velocityVX-r17`, `velocityVY-r17`, `velocityVZ-r17`:
X, Y, Z coordinate of satellite velocity state vector in ECEF. Unit is meter/second.
Step of 0.06 m/s. Actual value = field value * 0.06.
These parameters can be provided to the gNB in the conf file in the section `servingCellConfigCommon`:
```
...
cellSpecificKoffset_r17 = 478; # GEO satellite
# cellSpecificKoffset_r17 = 40; # LEO satellite
# GEO satellite
cellSpecificKoffset_r17 = 478;
ta-Common-r17 = 29314900; # 119.37 ms
positionX-r17 = 0;
positionY-r17 = 0;
positionZ-r17 = 32433846;
velocityVX-r17 = 0;
velocityVY-r17 = 0;
velocityVZ-r17 = 0;
# LEO satellite
# cellSpecificKoffset_r17 = 40;
# ta-Common-r17 = 2317000; # 9.435 ms
# ta-CommonDrift-r17 = -230000; # -46 µs/s
# positionX-r17 = 0;
# positionY-r17 = -2166908; # -2816980.4 m
# positionZ-r17 = 4910784; # 6384019.2 m
# velocityVX-r17 = 0;
# velocityVY-r17 = 115246; # 6914.76 m/s
# velocityVZ-r17 = 50853; # 3051.18 m/s
...
```
@@ -262,10 +296,11 @@ To enable this feature, the `disable_harq` flag has to be added to the gNB conf
...
```
So with these modifications to the file `targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band66.fr1.25PRB.usrpx300.conf` an example gNB command for FDD, 5 MHz BW, 15 kHz SCS, transparent GEO satellite 5G NR NTN is this:
The settings for a transparent GEO satellite scenario are already provided in the file `ci-scripts/conf_files/gnb.sa.band66.ntn.25prb.rfsim.conf`.
Using this conf file, an example gNB command for FDD, 5 MHz BW, 15 kHz SCS, transparent GEO satellite 5G NR NTN is this:
```
cd cmake_targets
sudo ./ran_build/build/nr-softmodem -O ../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band66.fr1.25PRB.usrpx300.conf --rfsim --rfsimulator.prop_delay 238.74
sudo ./ran_build/build/nr-softmodem -O ../ci-scripts/conf_files/gnb.sa.band66.ntn.25prb.rfsim.conf --rfsim
```
To configure NTN gNB with 32 HARQ processes in downlink and uplink, add these settings in conf files under section `gNBs.[0]`
@@ -281,32 +316,43 @@ To simulate a LEO satellite channel model with rfsimulator in UL (DL is simulate
@include "channelmod_rfsimu_LEO_satellite.conf"
```
So with these modifications to the file `targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band66.fr1.25PRB.usrpx300.conf` an example gNB command for FDD, 5 MHz BW, 15 kHz SCS, trasparent LEO satellite 5G NR NTN is this:
The settings for a transparent LEO satellite scenario are already provided in the file `ci-scripts/conf_files/gnb.sa.band66.ntn.leo.25prb.rfsim.conf`.
Using this conf file, an example gNB command for FDD, 5 MHz BW, 15 kHz SCS, trasparent LEO satellite 5G NR NTN is this:
```
cd cmake_targets
sudo ./ran_build/build/nr-softmodem -O ../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band66.fr1.25PRB.usrpx300.conf --rfsim --rfsimulator.prop_delay 20
sudo ./ran_build/build/nr-softmodem -O ../ci-scripts/conf_files/gnb.sa.band66.ntn.leo.25prb.rfsim.conf --rfsim
```
### NR UE
At UE side, there are two main parameters to cope with the large NTN propagation delay, cellSpecificKoffset and ta-Common.
`cellSpecificKoffset` is the same as for gNB and can be provided to the UE via command line parameter `--ntn-koffset`.
`ta-Common` is a common timing advance and can be provided to the UE via command line parameter `--ntn-ta-common` in milliseconds.
At UE side, only few parameters have to be provided, as the UE receives most relevant parameters via SIB19 from the gNB.
But to calculate the UE specific TA, the UE position has to be provided in the `ue.conf` file.
Also the LEO channel model has to be configured, e.g. by using an `@include` statement, just like on the gNB side:
```
...
position0 = {
x = 0.0;
y = 0.0;
z = 6377900.0;
}
@include "channelmod_rfsimu_LEO_satellite.conf"
```
So an example NR UE command for FDD, 5MHz BW, 15 kHz SCS, transparent GEO satellite 5G NR NTN is this:
```
cd cmake_targets
sudo ./ran_build/build/nr-uesoftmodem --band 66 -C 2152680000 --CO -400000000 -r 25 --numerology 0 --ssb 48 --rfsim --rfsimulator.prop_delay 238.74 --ntn-koffset 478 --ntn-ta-common 477.48
sudo ./ran_build/build/nr-uesoftmodem -O ../targets/PROJECTS/GENERIC-NR-5GC/CONF/ue.conf --band 66 -C 2152680000 --CO -400000000 -r 25 --numerology 0 --ssb 48 --rfsim --rfsimulator.prop_delay 238.74
```
For LEO satellites a third parameter specifying the NTN propagation delay drift has ben added, ta-CommonDrift.
`ta-CommonDrift` provides the drift rate of the common timing advance and can be provided to the UE via command line parameter `--ntn-ta-commondrift` in microseconds per second.
For LEO satellite scenarios, the parameter `--ntn-initial-time-drift` must be provided via command line, as the UE needs this value to compensate for the time drift during initial sync, before SIB19 was received.
This parameter provides the drift rate of the complete DL timing (incl. feeder link and service link) in µs/s.
Also, to perform an autonomous TA update based on the DL drift, the boolean parameter `--autonomous-ta` should be added in case of a LEO satellite scenario.
So an example NR UE command for FDD, 5MHz BW, 15 kHz SCS, transparent LEO satellite 5G NR NTN is this:
```
cd cmake_targets
sudo ./ran_build/build/nr-uesoftmodem --band 66 -C 2152680000 --CO -400000000 -r 25 --numerology 0 --ssb 48 --rfsim --rfsimulator.prop_delay 20 --rfsimulator.options chanmod -O ../targets/PROJECTS/GENERIC-NR-5GC/CONF/channelmod_rfsimu_LEO_satellite.conf --time-sync-I 0.2 --ntn-koffset 40 --ntn-ta-common 37.74 --ntn-ta-commondrift -50 --autonomous-ta
sudo ./ran_build/build/nr-uesoftmodem -O ../targets/PROJECTS/GENERIC-NR-5GC/CONF/ue.conf --band 66 -C 2152680000 --CO -400000000 -r 25 --numerology 0 --ssb 48 --rfsim --rfsimulator.prop_delay 20 --rfsimulator.options chanmod --time-sync-I 0.1 --ntn-initial-time-drift -46 --autonomous-ta
```
# Specific OAI modes