NR_UE: fix frequency offset estimation/compensation if SSB is in the second captured frame

openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c

@@ -251,17 +251,19 @@ int nr_initial_sync(UE_nr_rxtx_proc_t *proc,
 
     /* process pss search on received buffer */
     sync_pos = pss_synchro_nr(ue, is, NO_RATE_CHANGE);
+    if (sync_pos < fp->nb_prefix_samples)
+      continue;
 
-    if (sync_pos >= fp->nb_prefix_samples)
     ue->ssb_offset = sync_pos - fp->nb_prefix_samples;
-    else
-      ue->ssb_offset = sync_pos + fp->samples_per_frame - fp->nb_prefix_samples;
 
 #ifdef DEBUG_INITIAL_SYNCH
     LOG_I(PHY,"[UE%d] Initial sync : Estimated PSS position %d, Nid2 %d\n", ue->Mod_id, sync_pos,ue->common_vars.eNb_id);
     LOG_I(PHY,"sync_pos %d ssb_offset %d \n",sync_pos,ue->ssb_offset);
 #endif
 
+    /* check that SSS/PBCH block is continuous inside the received buffer */
+    if (ue->ssb_offset + NR_N_SYMBOLS_SSB * (fp->ofdm_symbol_size + fp->nb_prefix_samples) < fp->samples_per_frame) {
+
       // digital compensation of FFO for SSB symbols
       if (ue->UE_fo_compensation){
         double s_time = 1/(1.0e3*fp->samples_per_subframe);  // sampling time
@@ -271,10 +273,10 @@ int nr_initial_sync(UE_nr_rxtx_proc_t *proc,
         // and we do not know yet in which slot it goes.
 
         // start for offset correction
-      int start = sa ? is*fp->samples_per_frame : is*fp->samples_per_frame + ue->ssb_offset;
+        int start = is*fp->samples_per_frame;
 
         // loop over samples
-      int end = sa ? n_frames*fp->samples_per_frame : start + NR_N_SYMBOLS_SSB*(fp->ofdm_symbol_size + fp->nb_prefix_samples);
+        int end = start + fp->samples_per_frame;
 
         for(int n=start; n<end; n++){
           for (int ar=0; ar<fp->nb_antennas_rx; ar++) {
@@ -286,9 +288,6 @@ int nr_initial_sync(UE_nr_rxtx_proc_t *proc,
         }
       }
 
-    /* check that SSS/PBCH block is continuous inside the received buffer */
-    if (is*fp->samples_per_frame + ue->ssb_offset + NR_N_SYMBOLS_SSB * (fp->ofdm_symbol_size + fp->nb_prefix_samples) < n_frames*fp->samples_per_frame) {
-
       /* slop_fep function works for lte and takes into account begining of frame with prefix for subframe 0 */
       /* for NR this is not the case but slot_fep is still used for computing FFT of samples */
       /* in order to achieve correct processing for NR prefix samples is forced to 0 and then restored after function call */
@@ -322,10 +321,10 @@ int nr_initial_sync(UE_nr_rxtx_proc_t *proc,
         // and we do not know yet in which slot it goes.
 
         // start for offset correction
-        int start = sa ? is*fp->samples_per_frame : is*fp->samples_per_frame + ue->ssb_offset;
+        int start = is*fp->samples_per_frame;
 
         // loop over samples
-        int end = sa ? n_frames*fp->samples_per_frame-1 : start + NR_N_SYMBOLS_SSB*(fp->ofdm_symbol_size + fp->nb_prefix_samples);
+        int end = start + fp->samples_per_frame;
 
         for(int n=start; n<end; n++){
           for (int ar=0; ar<fp->nb_antennas_rx; ar++) {