Update RUNMODEM.md

doc/RUNMODEM.md

@@ -93,6 +93,14 @@ At the UE the --phy-test flag will
 
 ```bash sudo ./nr-uesoftmodem --phy-test [--rrc_config_path ../../../ci-scripts/rrc-files]```
 
+Some other useful paramters of the UE are
+
+--ue-fo-compensation: enables the frequency offset compenstation at the UE. This is useful when running over the air and/or without an external clock/time source
+--usrp-args: this is the equivalend paramter of sdr_addrs field in the gNB config file and can be used to identify the USRP and set some basic paramters (like the clock source)
+--clock-source: sets the clock-source (internal or external). 
+--time-source: sets the time-source (internal or external). 
+
+
 ## noS1 setup with OAI UE
 
 Instead of randomly generated payload, in the phy-test mode we can also inject/receive user-plane traffic over a TUN interface. This is the so-called noS1 mode.