- By default this value is equal to 0 at gNB in case of ulsim, but
    has a value in case of RF simulator
  - The N_TA_offset was calculated but not used at UE side

  - The number of nb_dmrs_re at gNB side was set to 6, but here it is assumed
    that there will be no data allocation in OFDM symbols that carry DMRS
  - nb_dmrs_re that is being given as an input to the TBS calculation,
    should be multiplied by the number of DMRS symbols in order to get the total
    number of DMRS REs per RB
  - In the calculation of G, only the number of DMRS per RB in 1 OFDM symbol should
    be given as an input, because inside the function of the G calculation, this
    number is being multiplied by the number of OFDM symbols that carry DMRS

- get preamble from rach_ConfigDedicated in contention free mode
- do preamble selection only in prach slot

- in phy-test both rnti are set to same rnti
- in do-ra the scrambling rnti is set to 0 while the polar rnti is the RA_rnti (computed as per
  TS 38.321)

- restructured nr_pdcch_unscrambling function
- minor cleanups
- formatting

- NR UE scheduled response for RA PDSCH case
- UE processing of RAR DCI
- some cleanup and formatting

NR fix downlink IP

See merge request oai/openairinterface5g!806

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

- this was necessary because as soon as the gNB starts, it tries detecting
  the prach preambles and it mesaures the background noise. However, there is
  a delay of several dozens of frames before it considers the preables as
  detected.
- the solution at the UE consists in avoiding sending preamble as soon as the
  UE syncs by introducing an offset, this keeps the power measurements low at
  gNB side as long as the preamble detection counter is under threshold

See merge request oai/openairinterface5g!804

Develop Integration Branch : 2020 week 15

The following Merge Requests have been included :

* MR 789 : fix sync source configuration for eNB and B200-mini
* MR 795 : dft/fft in shared lib
* MR 795 : NR gNB SCF indication
* MR 798 : Improvements on the "default" LTE-4G scheduler

ENDC S1-U gNB support: Separate some GTP functions between eNB and gNB. Downlink traffic from SGW arrives properly at gNB now after path switch

Merge remote-tracking branch 'origin/NR_RRCConfiguration_sync_source' into develop_integration_2020_w15_bis

Instead of looping over UEs and all DL config Req/HI DCI0, loop first
over all DL config Req/HI DCI0, and for each, match UE.  Lowers CPU
traffic for high traffic situations.

Merge branch 'NR_RRC_PRACH_procedures' of https://gitlab.eurecom.fr/oai/openairinterface5g into NR_RRC_PRACH_procedures