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/NR_REFSIG/nr_dmrs_rx.c

@@ -202,7 +202,7 @@ int nr_pdcch_dmrs_rx(PHY_VARS_NR_UE *ue,
   return(0);
 }
 
-void nr_pbch_dmrs_rx(int symbol, unsigned int *nr_gold_pbch, c16_t *output, bool sidelink)
+void nr_pbch_dmrs_rx(int symbol, const unsigned int *nr_gold_pbch, c16_t *output, bool sidelink)
 {
   int m,m0,m1;
   uint8_t idx=0;

openair1/PHY/NR_REFSIG/nr_gold_ue.c

@@ -21,15 +21,13 @@
 
 #include "refsig_defs_ue.h"
 
-void nr_gold_pbch(PHY_VARS_NR_UE* ue)
+void nr_gold_pbch(uint32_t nr_gold_pbch[2][64][NR_PBCH_DMRS_LENGTH_DWORD], int Nid, int Lmax)
 {
   unsigned int n = 0, x1 = 0, x2 = 0;
-  unsigned int Nid, i_ssb, i_ssb2;
-  unsigned char Lmax, l, n_hf, N_hf;
+  unsigned int i_ssb, i_ssb2;
+  unsigned char l, n_hf, N_hf;
   uint8_t reset;
 
-  Nid = ue->frame_parms.Nid_cell;
-  Lmax = ue->frame_parms.Lmax;
   N_hf = (Lmax == 4)? 2:1;
 
   for (n_hf = 0; n_hf < N_hf; n_hf++) {
@@ -42,7 +40,7 @@ void nr_gold_pbch(PHY_VARS_NR_UE* ue)
       x2 = (1<<11) * (i_ssb2 + 1) * ((Nid>>2) + 1) + (1<<6) * (i_ssb2 + 1) + (Nid&3);
 
       for (n=0; n<NR_PBCH_DMRS_LENGTH_DWORD; n++) {
-        ue->nr_gold_pbch[n_hf][l][n] = lte_gold_generic(&x1, &x2, reset);
+        nr_gold_pbch[n_hf][l][n] = lte_gold_generic(&x1, &x2, reset);
         reset = 0;
       }
 

openair1/PHY/NR_REFSIG/pss_nr.h

@@ -76,8 +76,15 @@
 #define SYNCF_TMP_SIZE                 (SYNCHRO_FFT_SIZE_MAX*IQ_SIZE)
 
 void init_context_synchro_nr(NR_DL_FRAME_PARMS *frame_parms_ue);
-void free_context_synchro_nr(void);
-int pss_synchro_nr(PHY_VARS_NR_UE *PHY_vars_UE, int is, int rate_change);
+int pss_synchro_nr(const c16_t **rxdata,
+                   const NR_DL_FRAME_PARMS *frame_parms,
+                   const c16_t pssTime[NUMBER_PSS_SEQUENCE][frame_parms->ofdm_symbol_size],
+                   int is,
+                   bool fo_flag,
+                   int target_Nid_cell,
+                   int *nid2,
+                   int *f_off);
+void generate_pss_nr_time(const NR_DL_FRAME_PARMS *fp, const int N_ID_2, int ssbFirstSCS, c16_t pssTime[fp->ofdm_symbol_size]);
 int16_t *get_primary_synchro_nr2(const int nid2);
 
 #endif /* PSS_NR_H */

openair1/PHY/NR_REFSIG/refsig_defs_ue.h

@@ -30,7 +30,7 @@
 /*!\brief This function generates the NR Gold sequence (38-211, Sec 5.2.1) for the PBCH DMRS.
 @param PHY_VARS_NR_UE* ue structure provides configuration, frame parameters and the pointers to the 32 bits sequence storage tables
  */
-void nr_pbch_dmrs_rx(int dmrss, unsigned int *nr_gold_pbch, c16_t *output, bool sidelink);
+void nr_pbch_dmrs_rx(int dmrss, const unsigned int *nr_gold_pbch, c16_t *output, bool sidelink);
 
 /*!\brief This function generates the NR Gold sequence (38-211, Sec 5.2.1) for the PDCCH DMRS.
 @param PHY_VARS_NR_UE* ue structure provides configuration, frame parameters and the pointers to the 32 bits sequence storage tables
@@ -51,7 +51,7 @@ int nr_pdsch_dmrs_rx(PHY_VARS_NR_UE *ue,
                      unsigned short nb_pdsch_rb,
                      uint8_t config_type);
 
-void nr_gold_pbch(PHY_VARS_NR_UE* ue);
+void nr_gold_pbch(uint32_t nr_gold_pbch[2][64][NR_PBCH_DMRS_LENGTH_DWORD], int Nid, int Lmax);
 
 void nr_gold_pdcch(PHY_VARS_NR_UE* ue,
                    unsigned short n_idDMRS);

openair1/PHY/NR_REFSIG/sss_nr.h

@@ -95,11 +95,15 @@ void free_context_sss_nr(void);
 void insert_sss_nr(int16_t *sss_time,
                    NR_DL_FRAME_PARMS *frame_parms);
 
-bool rx_sss_nr(PHY_VARS_NR_UE *ue,
-               const UE_nr_rxtx_proc_t *proc,
+bool rx_sss_nr(const NR_DL_FRAME_PARMS *frame_parms,
+               int nid2,
+               int target_Nid_cell,
+               int freq_offset_pss,
+               int ssb_start_subcarrier,
+               int *Nid_cell,
                int32_t *tot_metric,
                uint8_t *phase_max,
                int *freq_offset_sss,
-               c16_t rxdataF[][ue->frame_parms.samples_per_slot_wCP]);
+               c16_t rxdataF[][frame_parms->samples_per_slot_wCP]);
 #endif /* SSS_NR_H */