GitLab

- 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

PRACH_PDU.prach_format now interpreted according to last version (March 2020) of 5G FAPI specs
fixing nr_prachsim

use snprintf() instead of sprintf() to avoid writes outside buffer limits

- now is consistent for both UE and gNB

- moved remaining PUSCH PDU configuration from ULSCH
  procedures entirely to MAC
- introduced a function for DMRS RE configuration
- cleaned up redundant code in ULSCH procedures
- fixed TBS computation for Msg3

- removed superfluos code
- formatting
- fixed logging
- removed redundant nr_get_dci_size (replaced by nr_dci_size)
- removed unused and long-time commented out functions @ UE side

- To enable PTRS use -T flag followed by 3 integers
- Example: ./nr_ulsim -T 2 0 2
- 1st Value is the list of arguments -> e.g. 2
- 2nd Value is for L_PTRS{0,1,2}     -> e.g. 0
- 3rd Value is for K_PTRS{2,4}       -> e.g. 2

removed AssertFatal in nr_ue_mac_procedures.c for nr_dlsim HARQ tests. For some unknown reason there are occasion 0 SDUs sent up to MAC which causes failure.

also do some code cleanup while at it...

FEATURE STATEMENT:
- Introduce linear phase error noise model in Uplink at UE
- Perform common phase error (CPE) estimation and compensation at gNB

SOLUTION:
- A linear phase shift model is introduced in simulation.
- PTRS symbols are used to perform estimation of CPE from DMRS compensated signal
- The estimated values are interpolated in time domain and signal is compensated for the CPE.
- PTRS processing is done in Frequency Domain for each symbol in a slot and
  LLR's are calculated for each symbol accordingly.

IMPLEMENTATION:
* sim.h/channle_sim.c
- Linear Phase Noise Generation model definition.
* nr_ul_channel_estimation.c/nr_ul_estimation.h
- CPE estimation from PTRS and DMRS compensated signal.
* nr_dmrs_rx.c/nr_refsig.h
- Regenerate PTRS symbols at gNB.
* nr_ulsch_demodulation.c
- Removed old PTRS processing code and move to a common PTRS processing function
* defs_gNB.h/init.c
- New PTRS variables definition and initialization
* nr_ulsch_ue.c
- Corrected PTRS parameter to get new PTRS symbols for each OFDM symbol

TESTING
* ulsim.c
- Added Phase noise, Enable PTRS signal and verified the output.

VERIFICATION
- The LLR are rotated back with estimated CPE and no error is observed in scrambling/decoding

implementation of missing symbol-based rotation for NR modulation/demodulation (Section 5.3 38.211). Tested with unitary simulators (ulsim/dlsim).
To be tested with gNB testbench and rfsimlator

remove "pdsch_vars_flp", "pdsch_vars_SI", "pdsch_vars_ra", "pdsch_vars_p" and "pdsch_vars_MCH", use per thread "pdsch_vars" instead

- Ensure that tx slot processing is done by the time trx_write_func() gets called

Also fixed bugs in ulsim and dlsim harq tests

- DM-RS type {1,2} was wrongly assigned to {1,2} instead of {0,1}
- Num DM-RS CDM groups without data is now taken into account in mthread
  decoding function
- number of DM-RS CDM groups without data for format 1_0 according to 5.1.6.2
  3GPP TS 38.214 version 15.9.0 Release 15:
-- the UE shall assume the number of DM-RS CDM groups without data is:
-- 1 (CDM group 0) for the case of PDSCH with allocation duration of 2 symb
-- 2 (CDM group {0,1}) for all other cases.