Refactor (RRC): drop isIntraFrequencyNeighbour flag and labelling

Remove the isIntraFrequencyNeighbour field and all code that sets or
uses it, simplifying neighbour cell handling and avoiding redundant
state in the RRC gNB code. The flag duplicated information that can be
derived from the neighbour absoluteFrequencySSB and the serving cell
SSB ARFCN, and intra-frequency neighbours are logged in the SIB3
preparation flow.

Changes:
- Remove isIntraFrequencyNeighbour from nr_neighbour_cell_t in
  openair2/RRC/NR/nr_rrc_defs.h
- Delete is_intra_frequency_neighbour() and
  label_intra_frequency_neighbours() helpers from
  openair2/RRC/NR/rrc_gNB_du.c
- Remove calls to label_intra_frequency_neighbours() from
  rrc_gNB_process_f1_setup_req() and
  rrc_gNB_process_f1_du_configuration_update() in rrc_gNB_du.c
- Stop setting .isIntraFrequencyNeighbour in the local
  nr_neighbour_cell_t neighbourConfig initializer in
  openair2/RRC/NR/rrc_gNB_mobility.c

openair2/RRC/NR/nr_rrc_defs.h

@@ -387,7 +387,6 @@ typedef struct {
   int band;
   plmn_id_t plmn;
   uint32_t tac;
-  bool isIntraFrequencyNeighbour;
   // SIB3 (intra-frequency neighbor cell-specific offsets)
   nr_neighbour_cell_sib3_t sib3;
   // SIB4 (inter-frequency neighbor cell-specific parameters)

openair2/RRC/NR/rrc_gNB_du.c

@@ -538,41 +538,6 @@ static const neighbour_cell_configuration_t *get_cell_neighbour_list(const gNB_R
   return (const neighbour_cell_configuration_t *)it;
 }
 
-static void is_intra_frequency_neighbour(void *ssb_arfcn, void *neighbour_cell)
-{
-  uint32_t *ssb_arfcn_ptr = (uint32_t *)ssb_arfcn;
-  nr_neighbour_cell_t *neighbour_cell_ptr = (nr_neighbour_cell_t *)neighbour_cell;
-
-  if (*ssb_arfcn_ptr == neighbour_cell_ptr->absoluteFrequencySSB) {
-    LOG_D(NR_RRC, "HO LOG: found intra frequency neighbour %lu!\n", neighbour_cell_ptr->nrcell_id);
-    neighbour_cell_ptr->isIntraFrequencyNeighbour = true;
-  }
-}
-/**
- * @brief Labels neighbour cells if they are intra frequency to prepare meas config only for intra frequency ho
- * @param[in] rrc     Pointer to RRC instance
- * @param[in] cell    Pointer to cell container
- */
-static void label_intra_frequency_neighbours(gNB_RRC_INST *rrc, const nr_rrc_cell_container_t *cell)
-{
-  if (!rrc->neighbour_cell_configuration)
-    return;
-
-  const neighbour_cell_configuration_t *neighbour_cell_config = get_cell_neighbour_list(rrc, cell);
-  if (!neighbour_cell_config)
-    return;
-
-  uint32_t ssb_arfcn = get_ssb_arfcn(cell);
-  LOG_D(NR_RRC,
-        "Cell %lu (PCI %d, SSB ARFCN %u) has neighbour cell configuration, labeling intra-frequency neighbours\n",
-        cell->info.cell_id,
-        cell->info.pci,
-        ssb_arfcn);
-
-  const seq_arr_t *cell_neighbour_list = &neighbour_cell_config->neighbour_cells;
-  for_each((seq_arr_t *)cell_neighbour_list, (void *)&ssb_arfcn, is_intra_frequency_neighbour);
-}
-
 static bool valid_du_in_neighbour_configs(const seq_arr_t *neighbour_cell_configuration, const f1ap_served_cell_info_t *cell)
 {
   // MTC is mandatory, but some DUs don't send it in the F1 Setup Request, so
@@ -880,9 +845,6 @@ void rrc_gNB_process_f1_setup_req(f1ap_setup_req_t *req, sctp_assoc_t assoc_id)
       }
     }
 
-    if (new->mib != NULL &&new->sib1 != NULL)
-      label_intra_frequency_neighbours(rrc, new);
-
     resp.cells_to_activate[i] = cell;
   }
 
@@ -1098,10 +1060,6 @@ void rrc_gNB_process_f1_du_configuration_update(f1ap_gnb_du_configuration_update
         LOG_I(NR_RRC, "update system information of DU %ld\n", du->gNB_DU_id);
       }
     }
-
-    if (cell && cell->mib != NULL && cell->sib1 != NULL && cell->assoc_id == du->assoc_id) {
-      label_intra_frequency_neighbours(rrc, cell);
-    }
   }
 
   if (conf_up->num_cells_to_delete > 0) {

openair2/RRC/NR/rrc_gNB_mobility.c

@@ -607,7 +607,6 @@ void nr_HO_N2_trigger_telnet(gNB_RRC_INST *rrc, uint32_t neighbour_pci, uint32_t
   if (neighbour_pci == scell_pci) {
     LOG_I(NR_RRC, "UE %d: trigger handover on the same cell PCI=%d\n", rrc_ue_id, neighbour_pci);
     nr_neighbour_cell_t neighbourConfig = {
-        .isIntraFrequencyNeighbour = true,
         .gNB_ID = du->gNB_DU_id,
         .nrcell_id = pcell->info.cell_id,
         .physicalCellId = pcell->info.pci,