NR UE scan for SSB within current bandwidth

Till this commit, the UE gets the position of SSB in frequency from
command line and does the syncronization by locating the SSB in time. It
does this by generating a PSS time signal during initialization with the
SSB offset given via command line. Then PSS detection is done by
correlation.

In this commit, the UE computes a list of GSCN in the current NR band
that falls within the current bandwidth for the set center frequency.
For each GSCN in the list, the UE starts a thread and performs the
following:
1. Generate PSS time signal with SSB offset for current GSCN.
2. Detect PSS, SSS and decode PBCH (this step remains the same).
After all threads finishes, the results are collected.

For now, only the first detected PBCH is used to proceed further. So
this PBCH is indicated to MAC and UE exits initial sync.

Future work: The cell search can be standalone feature where the UE
could scan for SSB in the entire NR band. This would require changing
radio's frequency on the fly as the UE's bandwidth would not cover an
entire NR band. The cell detection can futher be imporved by looking
for SIB1 for each decoded PBCH.

openair1/PHY/MODULATION/modulation_UE.h

@@ -61,12 +61,11 @@ int sl_nr_slot_fep(PHY_VARS_NR_UE *ue,
                    uint32_t sample_offset,
                    c16_t rxdataF[][ue->SL_UE_PHY_PARAMS.sl_frame_params.samples_per_slot_wCP]);
 
-int nr_slot_fep_init_sync(PHY_VARS_NR_UE *ue,
-                          const UE_nr_rxtx_proc_t *proc,
+int nr_slot_fep_init_sync(const NR_DL_FRAME_PARMS *frame_parms,
                           unsigned char symbol,
                           int sample_offset,
-                          bool pbch_decoded,
-                          c16_t rxdataF[][ue->frame_parms.samples_per_slot_wCP],
+                          const c16_t **rxdata,
+                          c16_t rxdataF[][frame_parms->samples_per_slot_wCP],
                           int link_type);
 
 int slot_fep_mbsfn(PHY_VARS_UE *phy_vars_ue,