1.) Shutdown fix which allows us to see who requested to abort the simulation
2.) Properly initializing the NAS layer which previously was not happening for our simulation mode 5
3.) Changes in configurations to support the EPC(Have Melissa Verify these)
- removed redundant initialisation of variables
- introduced two "RF helpers" function that are replacing shared code in the sync routines
- added a new .c file and updated the cmakelists and .h files
- got rid of global variable fp
- code cleanup, removed redundant and unused code
- removed unused command line options and variables
- grouped command line setting in set_options function
- this reflects the implementation of IF and IF offset in the gNB RU
- the RF frequencies are set at HW level while the target frequencies are
stored in fp, therefore the values stored in fp should not be changed
after sync as only the tx/rx freq is updated
- removed overwritten dl/ul carrier frequencies in fp after sync
- removed redundant set of tx/rx freq in ue_synch (done in init_openair0)
- removed irrelevant set of dl/ul carrier freq in get_options
- adapted the get_band function: the algorithm is now taking into account
also the UL frequency in order to fetch the proper band (this was failing
before as some NR bands have the same DL band, e.g. band 65 and 66)
- added new bands to the NR table as per TS 38.101 V16.4.0 (2020)
- made the from_nrarfcn function compatible with UL FDD (this function,
used for both DL and UL was previously working with TDD only as it
did not compute properly the frequency for the UL FDD, throwing asserts)
- introduced common functions to get the NR table idx and the duplex mode,
removing repeated code in the process
- removed the unused function to get the uldl offset
- improved some logging
- other minor fixes to the relevant code
- the RU now supports IF equipment with custom FR1 TX/RX frequencies
- this configuration parameter together with the if_freq parameter allows
to set a custom IF RX frequency for the gNB
- if the IF offset is not specified, legacy code applies