Nodes get synchronization by NTP. TX and RX nodes loop over all the radio configurations until they are stopped or run out of battery.
Open a terminal in each node
For the TX node:
execute python experiment_tx.py
then >s and enter to start.
For the RX node:
execute python experiment_rx.py
then >s and enter to start.
Be sure to press enter in every terminal in the same minute, so all nodes start executing the code when the current minute changes to the next one.