more efficient measObjToAddModList reconfiguration by ensuring consistency in EARFCN ordering

srsenb/hdr/stack/rrc/ue_meas_cfg.h

@@ -68,10 +68,20 @@ bool compute_diff_meascfg(const asn1::rrc::meas_cfg_s& current_meascfg,
 
 bool fill_meascfg_enb_cfg(asn1::rrc::meas_cfg_s& meascfg, const cell_ctxt_dedicated_list& ue_cell_list);
 
-bool apply_meascfg_updates(asn1::rrc::meas_cfg_s&          meascfg,
+/**
-                           asn1::rrc::meas_cfg_s&          current_meascfg,
+ * Computes diff measConfig based on the previous measConfig and the UE current cells
+ * @param diff_meascfg resulting configuration to be added to the RRCConnectionReconf message
+ * @param prev_meascfg measConfig sent in the last RRCConnectionReconfiguration to the UE
+ * @param ue_cell_list contains the final list of cells configured in the UE after the Reconf procedure
+ * @param prev_earfcn  DL earfcn of Pcell in the last RRCReconf message
+ * @param prev_pci     pci of PCell in the last RRCReconf message
+ * @return true if updates exist that have been registered in diff_meascfg
+ */
+bool apply_meascfg_updates(asn1::rrc::meas_cfg_s&          diff_meascfg,
+                           asn1::rrc::meas_cfg_s&          prev_meascfg,
                            const cell_ctxt_dedicated_list& ue_cell_list,
-                           int                             prev_pci = -1);
+                           int                             prev_earfcn = -1,
+                           int                             prev_pci    = -1);
 
 } // namespace srsenb
 

srsenb/src/stack/rrc/rrc_mobility.cc

@@ -473,8 +473,8 @@ void rrc::ue::rrc_mobility::fill_mobility_reconf_common(asn1::rrc::dl_dcch_msg_s
   intralte.next_hop_chaining_count        = rrc_ue->ue_security_cfg.get_ncc();
 
   // Add MeasConfig of target cell
-  recfg_r8.meas_cfg_present =
+  recfg_r8.meas_cfg_present = apply_meascfg_updates(
-      apply_meascfg_updates(recfg_r8.meas_cfg, rrc_ue->current_ue_cfg.meas_cfg, rrc_ue->cell_ded_list, src_pci);
+      recfg_r8.meas_cfg, rrc_ue->current_ue_cfg.meas_cfg, rrc_ue->cell_ded_list, src_dl_earfcn, src_pci);
 
   apply_reconf_updates(recfg_r8,
                        rrc_ue->current_ue_cfg,

srsenb/src/stack/rrc/ue_meas_cfg.cc

@@ -338,9 +338,18 @@ bool fill_meascfg_enb_cfg(meas_cfg_s& meascfg, const cell_ctxt_dedicated_list& u
   const auto&             pcell_meascfg = pcell_cfg->cell_cfg.meas_cfg;
 
   // Add PCell+Scells to measObjToAddModList
+  // NOTE: sort by EARFCN to avoid unnecessary reconfigurations of measObjToAddModList
+  std::vector<const cell_ctxt_dedicated*> sorted_ue_cells(ue_cell_list.nof_cells());
   for (uint32_t ue_cc_idx = 0; ue_cc_idx < ue_cell_list.nof_cells(); ++ue_cc_idx) {
-    const auto* cell = ue_cell_list.get_ue_cc_idx(ue_cc_idx);
+    sorted_ue_cells[ue_cc_idx] = ue_cell_list.get_ue_cc_idx(ue_cc_idx);
-    add_meas_obj(meascfg.meas_obj_to_add_mod_list, cell->get_dl_earfcn());
+  }
+  std::sort(sorted_ue_cells.begin(),
+            sorted_ue_cells.end(),
+            [](const cell_ctxt_dedicated* cc1, const cell_ctxt_dedicated* cc2) {
+              return cc1->get_dl_earfcn() < cc2->get_dl_earfcn();
+            });
+  for (auto* cc : sorted_ue_cells) {
+    add_meas_obj(meascfg.meas_obj_to_add_mod_list, cc->get_dl_earfcn());
   }
 
   // Inserts all cells in meas_cell_list that are not PCell or SCells
@@ -403,23 +412,21 @@ bool compute_diff_meascfg(const meas_cfg_s& current_meascfg, const meas_cfg_s& t
 bool apply_meascfg_updates(meas_cfg_s&                     meascfg,
                            meas_cfg_s&                     current_meascfg,
                            const cell_ctxt_dedicated_list& ue_cell_list,
+                           int                             prev_earfcn,
                            int                             prev_pci)
 {
   meascfg = {};
 
-  const cell_ctxt_dedicated* pcell       = ue_cell_list.get_ue_cc_idx(UE_PCELL_CC_IDX);
+  const cell_ctxt_dedicated* pcell         = ue_cell_list.get_ue_cc_idx(UE_PCELL_CC_IDX);
-  uint32_t                   prev_earfcn = 0, target_earfcn = pcell->get_dl_earfcn();
+  uint32_t                   target_earfcn = pcell->get_dl_earfcn();
-  if (current_meascfg.meas_obj_to_add_mod_list_present) {
-    prev_earfcn = get_earfcn(current_meascfg.meas_obj_to_add_mod_list[0]);
-  }
 
-  if (static_cast<uint32_t>(prev_pci) == pcell->get_pci() and prev_earfcn == target_earfcn) {
+  if (static_cast<uint32_t>(prev_pci) == pcell->get_pci() and static_cast<uint32_t>(prev_earfcn) == target_earfcn) {
     // Shortcut: No PCell change -> no measConfig updates
     return false;
   }
 
   // Apply TS 36.331 5.5.6.1 - If Source and Target eNB EARFCNs do no match, update SourceMeasCfg.MeasIdList
-  if (prev_earfcn != target_earfcn) {
+  if ((uint32_t)prev_earfcn != target_earfcn) {
     meas_obj_t* found_target_obj = find_meas_obj(current_meascfg.meas_obj_to_add_mod_list, target_earfcn);
     meas_obj_t* found_src_obj    = prev_earfcn != 0 ? &current_meascfg.meas_obj_to_add_mod_list[0] : nullptr;
     if (found_target_obj != nullptr and found_src_obj != nullptr) {

srsenb/test/upper/rrc_meascfg_test.cc

@@ -24,6 +24,7 @@
 #include "srslte/common/test_common.h"
 #include "srslte/interfaces/enb_rrc_interface_types.h"
 #include "test_helpers.h"
+#include "srslte/rrc/rrc_cfg_utils.h"
 
 using namespace asn1::rrc;
 
@@ -279,6 +280,54 @@ int test_correct_meascfg_calculation()
   return SRSLTE_SUCCESS;
 }
 
+int test_minimize_meascfg_reordering()
+{
+  rrc_cfg_t          default_cfg, cfg1;
+  srsenb::all_args_t all_args;
+  TESTASSERT(test_helpers::parse_default_cfg(&default_cfg, all_args) == SRSLTE_SUCCESS);
+  cfg1                  = default_cfg;
+  cfg1.enb_id           = 0x19B;
+  cfg1.cell.nof_prb     = 6;
+  cfg1.meas_cfg_present = true;
+  cfg1.cell_list.resize(2);
+  cfg1.cell_list[0].dl_earfcn = 2850;
+  cfg1.cell_list[0].cell_id   = 0x01;
+  cfg1.cell_list[0].scell_list.resize(1);
+  cfg1.cell_list[0].scell_list[0].cell_id = 0x02;
+  cfg1.cell_list[0].meas_cfg.meas_cells.resize(1);
+  cfg1.cell_list[0].meas_cfg.meas_cells[0]     = generate_cell1();
+  cfg1.cell_list[0].meas_cfg.meas_cells[0].pci = 3;
+  cfg1.cell_list[1].dl_earfcn                  = 3400;
+  cfg1.cell_list[1].cell_id                    = 0x02;
+
+  cell_info_common_list cell_list{cfg1};
+  TESTASSERT(cell_list.nof_cells() == 2);
+  TESTASSERT(cell_list.get_cc_idx(0)->scells.size() == 1);
+  TESTASSERT(cell_list.get_cc_idx(0)->scells[0] == cell_list.get_cc_idx(1));
+  TESTASSERT(cell_list.get_cc_idx(1)->scells.empty());
+  freq_res_common_list     freq_res{cfg1};
+  cell_ctxt_dedicated_list ue_cell_list1{cfg1, freq_res, cell_list};
+  cell_ctxt_dedicated_list ue_cell_list2{cfg1, freq_res, cell_list};
+
+  meas_cfg_s mcfg1{}, mcfg2{};
+  ue_cell_list1.set_cells({0, 1});
+  ue_cell_list2.set_cells({1, 0});
+  TESTASSERT(fill_meascfg_enb_cfg(mcfg1, ue_cell_list1));
+  TESTASSERT(fill_meascfg_enb_cfg(mcfg2, ue_cell_list2));
+
+  // TEST1: Ensure consistent order of measObjects based on DL-EARFCN
+  TESTASSERT(mcfg1.meas_obj_to_add_mod_list_present and mcfg2.meas_obj_to_add_mod_list_present);
+  TESTASSERT(mcfg1.meas_obj_to_add_mod_list.size() == mcfg2.meas_obj_to_add_mod_list.size());
+  TESTASSERT(get_earfcn(mcfg1.meas_obj_to_add_mod_list[0]) == get_earfcn(mcfg2.meas_obj_to_add_mod_list[0]));
+  TESTASSERT(get_earfcn(mcfg1.meas_obj_to_add_mod_list[1]) == get_earfcn(mcfg2.meas_obj_to_add_mod_list[1]));
+  TESTASSERT(std::is_sorted(
+      mcfg1.meas_obj_to_add_mod_list.begin(), mcfg1.meas_obj_to_add_mod_list.end(), srslte::rrc_obj_id_cmp{}));
+  TESTASSERT(std::is_sorted(
+      mcfg2.meas_obj_to_add_mod_list.begin(), mcfg2.meas_obj_to_add_mod_list.end(), srslte::rrc_obj_id_cmp{}));
+
+  return SRSLTE_SUCCESS;
+}
+
 } // namespace srsenb
 
 int main(int argc, char** argv)
@@ -292,6 +341,7 @@ int main(int argc, char** argv)
   argparse::parse_args(argc, argv);
   TESTASSERT(test_correct_meascfg_insertion() == 0);
   TESTASSERT(test_correct_meascfg_calculation() == 0);
+  TESTASSERT(test_minimize_meascfg_reordering() == 0);
   srslte::console("Success\n");
 
   return 0;