NR_UE: fix PRACH TX timing for FR2

openair1/PHY/NR_UE_TRANSPORT/nr_prach.c

@@ -102,7 +102,11 @@ int32_t generate_nr_prach(PHY_VARS_NR_UE *ue, uint8_t gNB_id, uint8_t slot){
                        nrUE_config->prach_config.num_prach_fd_occasions_list[fd_occasion].prach_root_sequence_index,
                        ue->X_u);
 
-  sample_offset_slot = (prachStartSymbol==0?0:fp->ofdm_symbol_size*prachStartSymbol+fp->nb_prefix_samples0+fp->nb_prefix_samples*(prachStartSymbol-1));
+  if (slot % (fp->slots_per_subframe / 2) == 0)
+    sample_offset_slot = (prachStartSymbol==0?0:fp->ofdm_symbol_size*prachStartSymbol+fp->nb_prefix_samples0+fp->nb_prefix_samples*(prachStartSymbol-1));
+  else
+    sample_offset_slot = (fp->ofdm_symbol_size + fp->nb_prefix_samples) * prachStartSymbol;
+
   prach_start = fp->get_samples_slot_timestamp(slot, fp, 0) + sample_offset_slot;
 
   //printf("prachstartsymbold %d, sample_offset_slot %d, prach_start %d\n",prachStartSymbol, sample_offset_slot, prach_start);