fix edge case where serving cell is good enough for reestablishment but the sibs are not yet acquired

srsue/hdr/stack/rrc/rrc.h

@@ -329,7 +329,7 @@ private:
 
   // Senders
   void send_con_request(srslte::establishment_cause_t cause);
-  void send_con_restablish_request(asn1::rrc::reest_cause_e cause, uint16_t rnti, uint16_t pci);
+  void send_con_restablish_request(asn1::rrc::reest_cause_e cause, uint16_t rnti, uint16_t pci, uint32_t cellid);
   void send_con_restablish_complete();
   void send_con_setup_complete(srslte::unique_byte_buffer_t nas_msg);
   void send_ul_info_transfer(srslte::unique_byte_buffer_t nas_msg);

srsue/hdr/stack/rrc/rrc_cell.h

@@ -89,6 +89,7 @@ public:
 
   uint32_t get_cell_id() const { return (uint32_t)sib1.cell_access_related_info.cell_id.to_number(); }
 
+  bool has_sibs(srslte::span<uint32_t> indexes) const;
   bool has_sib(uint32_t index) const;
   bool has_sib1() const { return has_valid_sib1; }
   bool has_sib2() const { return has_valid_sib2; }

srsue/hdr/stack/rrc/rrc_procedures.h

@@ -288,9 +288,8 @@ private:
 
   rrc*                     rrc_ptr     = nullptr;
   asn1::rrc::reest_cause_e reest_cause = asn1::rrc::reest_cause_e::nulltype;
-  uint16_t                 reest_rnti        = 0;
-  uint16_t                 reest_source_pci  = 0;
-  uint32_t                 reest_source_freq = 0;
+  uint16_t                 reest_rnti = 0, reest_source_pci = 0;
+  uint32_t                 reest_source_freq = 0, reest_cellid = 0;
 
   bool                   passes_cell_criteria() const;
   srslte::proc_outcome_t cell_criteria();

srsue/src/stack/rrc/rrc.cc

@@ -723,25 +723,11 @@ void rrc::send_con_request(srslte::establishment_cause_t cause)
 }
 
 /* RRC connection re-establishment procedure (5.3.7.4) */
-void rrc::send_con_restablish_request(reest_cause_e cause, uint16_t crnti, uint16_t pci)
+void rrc::send_con_restablish_request(reest_cause_e cause, uint16_t crnti, uint16_t pci, uint32_t cellid)
 {
-  uint32_t cellid;
-
   // Clean reestablishment type
   reestablishment_successful = false;
 
-  if (cause == reest_cause_e::ho_fail) {
-    crnti  = ho_handler.get()->ho_src_rnti;
-    pci    = ho_handler.get()->ho_src_cell.get_pci();
-    cellid = ho_handler.get()->ho_src_cell.get_cell_id();
-  } else if (cause == reest_cause_e::other_fail) {
-    // use source PCI after RLF
-    cellid = meas_cells.serving_cell().get_cell_id();
-  } else {
-    pci    = meas_cells.serving_cell().get_pci();
-    cellid = meas_cells.serving_cell().get_cell_id();
-  }
-
   // Compute shortMAC-I
   uint8_t       varShortMAC_packed[16] = {};
   asn1::bit_ref bref(varShortMAC_packed, sizeof(varShortMAC_packed));
@@ -806,6 +792,10 @@ void rrc::send_con_restablish_request(reest_cause_e cause, uint16_t crnti, uint1
                    meas_cells.serving_cell().phy_cell.pci,
                    meas_cells.serving_cell().phy_cell.earfcn,
                    cause.to_string().c_str());
+  rrc_log->info("RRC Connection Reestablishment to PCI=%d, EARFCN=%d (Cause: \"%s\")\n",
+                meas_cells.serving_cell().phy_cell.pci,
+                meas_cells.serving_cell().phy_cell.earfcn,
+                cause.to_string().c_str());
   send_ul_ccch_msg(ul_ccch_msg);
 }
 

srsue/src/stack/rrc/rrc_cell.cc

@@ -75,6 +75,16 @@ uint32_t cell_t::timeout_secs(struct timeval now) const
   return t[0].tv_sec;
 }
 
+bool cell_t::has_sibs(srslte::span<uint32_t> indexes) const
+{
+  for (uint32_t idx : indexes) {
+    if (not has_sib(idx)) {
+      return false;
+    }
+  }
+  return true;
+}
+
 bool cell_t::has_sib(uint32_t index) const
 {
   switch (index) {

srsue/src/stack/rrc/rrc_procedures.cc

@@ -456,8 +456,9 @@ rrc::cell_selection_proc::cell_selection_proc(rrc* parent_) : rrc_ptr(parent_) {
  */
 proc_outcome_t rrc::cell_selection_proc::init(std::vector<uint32_t> required_sibs_)
 {
-  if (rrc_ptr->meas_cells.nof_neighbours() == 0 and rrc_ptr->phy_ctrl->is_in_sync() and
-      rrc_ptr->phy->cell_is_camping()) {
+  bool serv_cell_is_ok = rrc_ptr->phy_ctrl->is_in_sync() and rrc_ptr->phy->cell_is_camping();
+  if (rrc_ptr->meas_cells.nof_neighbours() == 0 and serv_cell_is_ok and
+      rrc_ptr->meas_cells.serving_cell().has_sibs(required_sibs_)) {
     // don't bother with cell selection if there are no neighbours and we are already camping
     Debug("Skipping Cell Selection Procedure as there are no neighbour and cell is camping.\n");
     cs_result = cs_result_t::same_cell;
@@ -482,6 +483,14 @@ proc_outcome_t rrc::cell_selection_proc::init(std::vector<uint32_t> required_sib
   }
   neigh_index = 0;
   cs_result   = cs_result_t::no_cell;
+  if (serv_cell_is_ok) {
+    state = search_state_t::cell_config;
+    if (not rrc_ptr->serv_cell_cfg.launch(&serv_cell_cfg_fut, required_sibs)) {
+      Warning("Failed to launch %s procedure\n", rrc_ptr->serv_cell_cfg.get()->name());
+      return proc_outcome_t::error;
+    }
+    return proc_outcome_t::yield;
+  }
   state                      = search_state_t::cell_selection;
   discard_serving            = false;
   serv_cell_select_attempted = false;
@@ -1159,18 +1168,26 @@ proc_outcome_t rrc::connection_reest_proc::init(asn1::rrc::reest_cause_e cause)
   }
 
   // Save reestablishment Cause and current C-RNTI context
-  reest_rnti        = uernti.crnti;
   reest_cause = cause;
+  if (reest_cause.value == reest_cause_opts::ho_fail) {
+    reest_rnti        = rrc_ptr->ho_handler.get()->ho_src_rnti;
+    reest_source_pci  = rrc_ptr->ho_handler.get()->ho_src_cell.get_pci();
+    reest_cellid      = rrc_ptr->ho_handler.get()->ho_src_cell.get_cell_id();
+    reest_source_freq = rrc_ptr->ho_handler.get()->ho_src_cell.get_earfcn();
+  } else {
+    reest_rnti        = uernti.crnti;
     reest_source_pci  = rrc_ptr->meas_cells.serving_cell().get_pci(); // needed for reestablishment with another cell
+    reest_cellid      = rrc_ptr->meas_cells.serving_cell().get_cell_id();
     reest_source_freq = rrc_ptr->meas_cells.serving_cell().get_earfcn();
+  }
 
-  Info("Starting... cause: \"%s\", UE context: {C-RNTI=0x%x, PCI=%d, DL-EARFCN=%d}\n",
+  Info("Starting... cause: \"%s\", UE context: {C-RNTI=0x%x, PCI=%d, CELL ID=%d}\n",
        reest_cause == asn1::rrc::reest_cause_opts::recfg_fail
            ? "Reconfiguration failure"
            : cause == asn1::rrc::reest_cause_opts::ho_fail ? "Handover failure" : "Other failure",
        reest_rnti,
        reest_source_pci,
-       reest_source_freq);
+       reest_cellid);
 
   // 5.3.7.2 - Initiation
 
@@ -1240,7 +1257,7 @@ srslte::proc_outcome_t rrc::connection_reest_proc::cell_criteria()
   // Not implemented yet.
 
   // 1> initiate transmission of the RRCConnectionReestablishmentRequest message in accordance with 5.3.7.4;
-  rrc_ptr->send_con_restablish_request(reest_cause, reest_rnti, reest_source_pci);
+  rrc_ptr->send_con_restablish_request(reest_cause, reest_rnti, reest_source_pci, reest_cellid);
 
   state = state_t::wait_reest_msg;
   return proc_outcome_t::yield;