add section with NR UE NTN example to doc/RUNMODEM.md

doc/RUNMODEM.md

@@ -188,6 +188,18 @@ cd cmake_targets
 sudo ./ran_build/build/nr-softmodem -O ../targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band66.fr1.25PRB.usrpx300.conf --sa --rfsim --rfsimulator.prop_delay 238.74
 ```
 
+### 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 timong advance and can be provided to the UE via command line parameter `--ntn-ta-common` in milliseconds.
+
+So an example NR UE command for FDD, 5MHz BW, 15 kHz SCS, 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 --sa --rfsim --rfsimulator.prop_delay 238.74 --ntn-koffset 478 --ntn-ta-common 477.48
+```
+
 # Specific OAI modes
 
 ## phy-test setup with OAI UE