- To modify DMRS use -U flag followed by 3 integers
- Example: ./nr_ulsim -U 2 1 0
- 1st Value is the list of arguments     -> e.g. 2
- 2nd Value is for TYPE{0=A,1=B}         -> e.g. 1
- 3rd Value is for ADD_POS{0,1,2,3}      -> e.g. 0

- 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

- New Data Structure to store PTRS RE's is removed
- LLR's are calculated at the end symbol for whole slot

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

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Develop integration 2020 week 34

The following merge requests have been included:

* MR [859] : Fixed the bug not sending MSG3
* MR [860] : FeMBMS eNB / UE End-to-End chain
* MR [866] : Improved modulation speed
* MR [872] : Improvement on CUDA GPU ldpc latency

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

# Conflicts:
#   openair1/PHY/NR_UE_TRANSPORT/nr_ulsch_ue.c

Develop integration: 2020 week 33

The following Merge Requests are included:

* MR [849] : Implement Message2 (RAR) reception for NR-UE
* MR [870] : Fix softmodem restart
* MR [871] : Fix support for MIMO in rf-simulator
* MR [873] : BUILD: fix for new API on load_softscope

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

Problem STATEMENT:
- When enabling PTRS flag in ulsim, there are multiple scrambling and decoding errors
  are observed even with high SNR values
  SNR 60dB   errors_scrambling 5546/13800
  Channel BLER 1.000000e+00, Channel BER 4.018841e-01

ANALYSIS:
- While extracting PTRS RE's, the PUSCH RE count was not updated accordingly for PTRS symbols.
- This results in 0 value LLR's on same positions which cause offset issue in later processing.

IMPLEMENTATION:
* nr_ulsch_demodulation.c
- In case of PTRS symbol, respective total number of PTRS RE's are subtracted from available
  PUSCH RE's in each PUSCH Symbol processing.

TESTING
* ulsim.c
- PTRS are enabled for testing and are not enabled by default by this commit.
- Available bit count is adjusted if PTRS is enabled.

VERIFICATION
- Total Scrambling errors after gNb processing shall be only 250 bits (in K=2)
  which were replaced with PTRS at UE side while transmission.
  SNR 60.000000 errors_scrambling 250/13800
  Channel BLER 0.000000e+00, Channel BER 1.811594e-02
- After adjusting available bits in ulsim.c for error calculation
  SNR 60.000000: n_errors errors_scrambling 0/13550
  Channel BLER 0.000000e+00, Channel BER 0.000000e+00

EXTRA
- Removed white-spaces from all above mentioned files
- Added Global/vim tags to .gitignore file

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Conflicts:
	targets/ARCH/rfsimulator/simulator.c

See merge request oai/openairinterface5g!869

Develop Integration Branch : 2020 week 31

The following Merge Requests have been included:

* MR [861] : Fixes for buffer overrun when L1 information is cleared upon UE removal in
* MR [863] : Small fixes
* MR [864] : Fixed the bug no supporting CellId more than 256
* MR [865] : Fix to have the sony 5g connect in NSA mode
* MR [867] : CI improvements for OCP-enb testing and NSA FR1 testing
* MR [868] : Add chansimuparams

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>