added extra state to S1 target enb mobility FSM. Accounts for out-of-order arrival of MMEStatusTransfer. Also, now we avoid creating DRBs before the MMEStatusTransfer

srsenb/hdr/stack/rrc/rrc_bearer_cfg.h

@@ -81,15 +81,15 @@ public:
   void rr_ded_cfg_complete();
 
   // Methods to apply bearer updates
-  void apply_pdcp_bearer_updates(pdcp_interface_rrc* pdcp, const security_cfg_handler& ue_sec_cfg);
-  void apply_rlc_bearer_updates(rlc_interface_rrc* rlc);
   void add_gtpu_bearer(gtpu_interface_rrc* gtpu, uint32_t erab_id);
   void fill_pending_nas_info(asn1::rrc::rrc_conn_recfg_r8_ies_s* msg);
 
   const std::map<uint8_t, erab_t>&                get_erabs() const { return erabs; }
   const asn1::rrc::drb_to_add_mod_list_l&         get_established_drbs() const { return current_drbs; }
   const asn1::rrc::srb_to_add_mod_list_l&         get_established_srbs() const { return current_srbs; }
-  const asn1::rrc::drb_to_add_mod_list_l& get_pending_addmod_drbs() const { return drbs_to_add; }
+  srslte::span<const asn1::rrc::drb_to_add_mod_s> get_pending_addmod_drbs() const { return drbs_to_add; }
+  srslte::span<const uint8_t>                     get_pending_rem_drbs() const { return drbs_to_release; }
+  srslte::span<const asn1::rrc::srb_to_add_mod_s> get_pending_addmod_srbs() const { return srbs_to_add; }
 
   std::map<uint8_t, std::vector<uint8_t> > erab_info_list;
   std::map<uint8_t, erab_t>                erabs;

srsenb/hdr/stack/rrc/rrc_mobility.h

@@ -114,7 +114,6 @@ public:
   // S1-Handover
   bool start_s1_tenb_ho(const asn1::s1ap::ho_request_s&                                   msg,
                         const asn1::s1ap::sourceenb_to_targetenb_transparent_container_s& container);
-  void set_erab_status(const asn1::s1ap::bearers_subject_to_status_transfer_list_l& erabs);
 
 private:
   // Handover from source cell
@@ -139,6 +138,7 @@ private:
 
   // vars
   std::shared_ptr<const var_meas_cfg_t> ue_var_meas;
+  asn1::rrc::rrc_conn_recfg_complete_s  pending_recfg_complete;
 
   // events
   struct ho_meas_report_ev {
@@ -152,6 +152,7 @@ private:
   };
   using unsuccessful_outcome_ev = std::false_type;
   using recfg_complete_ev       = asn1::rrc::rrc_conn_recfg_complete_s;
+  using status_transfer_ev      = asn1::s1ap::bearers_subject_to_status_transfer_list_l;
 
   // states
   struct idle_st {};
@@ -163,6 +164,7 @@ private:
     void enter(rrc_mobility* f, const ho_meas_report_ev& meas_report);
   };
   struct s1_target_ho_st {};
+  struct wait_recfg_comp {};
   struct s1_source_ho_st : public subfsm_t<s1_source_ho_st> {
     ho_meas_report_ev report;
     using ho_cmd_msg = srslte::unique_byte_buffer_t;
@@ -204,16 +206,19 @@ private:
 
   // FSM transition handlers
   void handle_crnti_ce(intraenb_ho_st& s, const user_crnti_upd_ev& ev);
-  void handle_recfg_complete(s1_target_ho_st& s, const recfg_complete_ev& ev);
   void handle_recfg_complete(intraenb_ho_st& s, const recfg_complete_ev& ev);
   void handle_ho_req(idle_st& s, const ho_req_rx_ev& ho_req);
+  void handle_status_transfer(s1_target_ho_st& s, const status_transfer_ev& ev);
+  void defer_recfg_complete(s1_target_ho_st& s, const recfg_complete_ev& ev);
+  void handle_recfg_complete(wait_recfg_comp& s, const recfg_complete_ev& ev);
 
 protected:
   // states
-  state_list<idle_st, intraenb_ho_st, s1_target_ho_st, s1_source_ho_st> states{this,
+  state_list<idle_st, intraenb_ho_st, s1_target_ho_st, wait_recfg_comp, s1_source_ho_st> states{this,
                                                                                                 idle_st{},
                                                                                                 intraenb_ho_st{},
                                                                                                 s1_target_ho_st{},
+                                                                                                wait_recfg_comp{},
                                                                                                 s1_source_ho_st{this}};
 
   // transitions
@@ -221,16 +226,18 @@ protected:
   // clang-format off
   using transitions = transition_table<
   //      Start         Target              Event                Action                      Guard
-  // +----------------+----------------+--------------------+---------------------------+-------------------------+
+  // +----------------+-------------------+---------------------+----------------------------+-------------------------+
   row< idle_st,         s1_source_ho_st,   ho_meas_report_ev,   nullptr,                      &fsm::needs_s1_ho        >,
   row< idle_st,         intraenb_ho_st,    ho_meas_report_ev,   nullptr,                      &fsm::needs_intraenb_ho  >,
   row< idle_st,         s1_target_ho_st,   ho_req_rx_ev,        &fsm::handle_ho_req                                    >,
-  // +----------------+----------------+--------------------+---------------------------+-------------------------+
+  // +----------------+-------------------+---------------------+----------------------------+-------------------------+
   upd< intraenb_ho_st,                     user_crnti_upd_ev,   &fsm::handle_crnti_ce                                  >,
   row< intraenb_ho_st,  idle_st,           recfg_complete_ev,   &fsm::handle_recfg_complete                            >,
-  // +----------------+----------------+--------------------+---------------------------+-------------------------+
+  // +----------------+-------------------+---------------------+----------------------------+-------------------------+
-  row< s1_target_ho_st, idle_st,         recfg_complete_ev, &fsm::handle_recfg_complete                           >
+  row< s1_target_ho_st, wait_recfg_comp,   status_transfer_ev,  &fsm::handle_status_transfer                           >,
-  // +----------------+----------------+--------------------+---------------------------+-------------------------+
+  upd< s1_target_ho_st,                    recfg_complete_ev,   &fsm::defer_recfg_complete                             >,
+  row< wait_recfg_comp, idle_st,           recfg_complete_ev,   &fsm::handle_recfg_complete                            >
+  // +----------------+-------------------+---------------------+----------------------------+-------------------------+
   >;
   // clang-format on
 };

srsenb/hdr/stack/rrc/rrc_ue.h

@@ -174,6 +174,14 @@ private:
    * @param reconfig_r8 ASN1 reconfiguration message
    */
   void apply_reconf_phy_config(const asn1::rrc::rrc_conn_recfg_r8_ies_s& reconfig_r8);
+
+  /**
+   * Reconfigures PDCP bearers
+   * @param srbs_to_add SRBs to add
+   */
+  void apply_pdcp_srb_updates();
+  void apply_pdcp_drb_updates();
+  void apply_rlc_rb_updates();
 }; // class ue
 
 } // namespace srsenb

srsenb/src/stack/rrc/rrc.cc

@@ -475,7 +475,7 @@ void rrc::set_erab_status(uint16_t rnti, const asn1::s1ap::bearers_subject_to_st
     rrc_log->warning("rnti=0x%x does not exist\n", rnti);
     return;
   }
-  ue_it->second->mobility_handler->set_erab_status(erabs);
+  ue_it->second->mobility_handler->trigger(erabs);
 }
 
 /*******************************************************************************

srsenb/src/stack/rrc/rrc_bearer_cfg.cc

@@ -339,56 +339,6 @@ bool bearer_cfg_handler::fill_rr_cfg_ded(asn1::rrc::rr_cfg_ded_s& msg)
   return msg.srb_to_add_mod_list_present or msg.drb_to_add_mod_list_present or msg.drb_to_release_list_present;
 }
 
-void bearer_cfg_handler::apply_pdcp_bearer_updates(pdcp_interface_rrc* pdcp, const security_cfg_handler& ue_sec_cfg)
-{
-  for (const srb_to_add_mod_s& srb : srbs_to_add) {
-    pdcp->add_bearer(rnti, srb.srb_id, srslte::make_srb_pdcp_config_t(srb.srb_id, false));
-
-    // For SRB2, enable security/encryption/integrity
-    if (ue_sec_cfg.is_as_sec_cfg_valid()) {
-      pdcp->config_security(rnti, srb.srb_id, ue_sec_cfg.get_as_sec_cfg());
-      pdcp->enable_integrity(rnti, srb.srb_id);
-      pdcp->enable_encryption(rnti, srb.srb_id);
-    }
-  }
-
-  for (uint8_t drb_id : drbs_to_release) {
-    pdcp->del_bearer(rnti, drb_id + 2);
-  }
-  for (const drb_to_add_mod_s& drb : drbs_to_add) {
-    // Configure DRB1 in PDCP
-    if (drb.pdcp_cfg_present) {
-      srslte::pdcp_config_t pdcp_cnfg_drb = srslte::make_drb_pdcp_config_t(drb.drb_id, false, drb.pdcp_cfg);
-      pdcp->add_bearer(rnti, drb.lc_ch_id, pdcp_cnfg_drb);
-    } else {
-      srslte::pdcp_config_t pdcp_cnfg_drb = srslte::make_drb_pdcp_config_t(drb.drb_id, false);
-      pdcp->add_bearer(rnti, drb.lc_ch_id, pdcp_cnfg_drb);
-    }
-
-    if (ue_sec_cfg.is_as_sec_cfg_valid()) {
-      pdcp->config_security(rnti, drb.lc_ch_id, ue_sec_cfg.get_as_sec_cfg());
-      pdcp->enable_integrity(rnti, drb.lc_ch_id);
-      pdcp->enable_encryption(rnti, drb.lc_ch_id);
-    }
-  }
-}
-
-void bearer_cfg_handler::apply_rlc_bearer_updates(rlc_interface_rrc* rlc)
-{
-  for (const srb_to_add_mod_s& srb : srbs_to_add) {
-    rlc->add_bearer(rnti, srb.srb_id, srslte::rlc_config_t::srb_config(srb.srb_id));
-  }
-  if (drbs_to_release.size() > 0) {
-    log_h->error("Removing DRBs not currently supported\n");
-  }
-  for (const drb_to_add_mod_s& drb : drbs_to_add) {
-    if (not drb.rlc_cfg_present) {
-      log_h->warning("Default RLC DRB config not supported\n");
-    }
-    rlc->add_bearer(rnti, drb.lc_ch_id, srslte::make_rlc_config_t(drb.rlc_cfg));
-  }
-}
-
 void bearer_cfg_handler::add_gtpu_bearer(srsenb::gtpu_interface_rrc* gtpu, uint32_t erab_id)
 {
   auto it = erabs.find(erab_id);

srsenb/src/stack/rrc/rrc_mobility.cc

@@ -763,36 +763,6 @@ bool rrc::ue::rrc_mobility::start_s1_tenb_ho(
   return is_in_state<s1_target_ho_st>();
 }
 
-void rrc::ue::rrc_mobility::set_erab_status(const asn1::s1ap::bearers_subject_to_status_transfer_list_l& erabs)
-{
-  for (const auto& erab : erabs) {
-    const auto& erab_item = erab.value.bearers_subject_to_status_transfer_item();
-    auto        erab_it   = rrc_ue->bearer_list.get_erabs().find(erab_item.erab_id);
-    if (erab_it == rrc_ue->bearer_list.get_erabs().end()) {
-      rrc_log->warning("The E-RAB Id=%d is not recognized\n", erab_item.erab_id);
-      continue;
-    }
-    const auto& drbs  = rrc_ue->bearer_list.get_pending_addmod_drbs();
-    uint8_t     drbid = erab_item.erab_id - 4;
-    auto        drb_it =
-        std::find_if(drbs.begin(), drbs.end(), [drbid](const drb_to_add_mod_s& drb) { return drb.drb_id == drbid; });
-    if (drb_it == drbs.end()) {
-      rrc_log->warning("The DRB id=%d does not exist\n", erab_item.erab_id - 4);
-    }
-
-    srslte::pdcp_lte_state_t drb_state{};
-    drb_state.tx_hfn          = erab_item.dl_coun_tvalue.hfn;
-    drb_state.next_pdcp_tx_sn = erab_item.dl_coun_tvalue.pdcp_sn;
-    drb_state.rx_hfn          = erab_item.ul_coun_tvalue.hfn;
-    drb_state.next_pdcp_rx_sn = erab_item.ul_coun_tvalue.pdcp_sn;
-    rrc_log->info("Setting lcid=%d PDCP state to {Tx SN: %d, Rx SN: %d}\n",
-                  drb_it->lc_ch_id,
-                  drb_state.next_pdcp_tx_sn,
-                  drb_state.next_pdcp_rx_sn);
-    rrc_enb->pdcp->set_bearer_state(rrc_ue->rnti, drb_it->lc_ch_id, drb_state);
-  }
-}
-
 bool rrc::ue::rrc_mobility::update_ue_var_meas_cfg(const asn1::rrc::meas_cfg_s& source_meas_cfg,
                                                    uint32_t                     target_enb_cc_idx,
                                                    asn1::rrc::meas_cfg_s*       diff_meas_cfg)
@@ -1113,9 +1083,9 @@ void rrc::ue::rrc_mobility::handle_ho_req(idle_st& s, const ho_req_rx_ev& ho_req
   ho_cmd_pdu->N_bytes = bref2.distance_bytes();
 
   /* Configure remaining layers based on pending changes */
-  // Update RLC + PDCP
+  // Update RLC + PDCP SRBs (no DRBs until MME Status Transfer)
-  rrc_ue->bearer_list.apply_pdcp_bearer_updates(rrc_enb->pdcp, rrc_ue->ue_security_cfg);
+  rrc_ue->apply_pdcp_srb_updates();
-  rrc_ue->bearer_list.apply_rlc_bearer_updates(rrc_enb->rlc);
+  rrc_ue->apply_rlc_rb_updates();
   // Update MAC
   rrc_ue->mac_ctrl->handle_ho_prep(hoprep_r8, recfg_r8);
   // Apply PHY updates
@@ -1195,7 +1165,7 @@ bool rrc::ue::rrc_mobility::apply_ho_prep_cfg(const ho_prep_info_r8_ies_s&    ho
   return true;
 }
 
-void rrc::ue::rrc_mobility::handle_recfg_complete(s1_target_ho_st& s, const recfg_complete_ev& ev)
+void rrc::ue::rrc_mobility::handle_recfg_complete(wait_recfg_comp& s, const recfg_complete_ev& ev)
 {
   cell_ctxt_dedicated* target_cell = rrc_ue->cell_ded_list.get_ue_cc_idx(UE_PCELL_CC_IDX);
   rrc_log->info("User rnti=0x%x successfully handovered to cell_id=0x%x\n",
@@ -1206,6 +1176,51 @@ void rrc::ue::rrc_mobility::handle_recfg_complete(s1_target_ho_st& s, const recf
   rrc_enb->s1ap->send_ho_notify(rrc_ue->rnti, target_eci);
 }
 
+void rrc::ue::rrc_mobility::handle_status_transfer(s1_target_ho_st& s, const status_transfer_ev& erabs)
+{
+  // Establish DRBs
+  rrc_ue->apply_pdcp_drb_updates();
+
+  // Set DRBs SNs
+  for (const auto& erab : erabs) {
+    const auto& erab_item = erab.value.bearers_subject_to_status_transfer_item();
+    auto        erab_it   = rrc_ue->bearer_list.get_erabs().find(erab_item.erab_id);
+    if (erab_it == rrc_ue->bearer_list.get_erabs().end()) {
+      rrc_log->warning("The E-RAB Id=%d is not recognized\n", erab_item.erab_id);
+      continue;
+    }
+    const auto& drbs  = rrc_ue->bearer_list.get_pending_addmod_drbs();
+    uint8_t     drbid = erab_item.erab_id - 4;
+    auto        drb_it =
+        std::find_if(drbs.begin(), drbs.end(), [drbid](const drb_to_add_mod_s& drb) { return drb.drb_id == drbid; });
+    if (drb_it == drbs.end()) {
+      rrc_log->warning("The DRB id=%d does not exist\n", erab_item.erab_id - 4);
+    }
+
+    srslte::pdcp_lte_state_t drb_state{};
+    drb_state.tx_hfn          = erab_item.dl_coun_tvalue.hfn;
+    drb_state.next_pdcp_tx_sn = erab_item.dl_coun_tvalue.pdcp_sn;
+    drb_state.rx_hfn          = erab_item.ul_coun_tvalue.hfn;
+    drb_state.next_pdcp_rx_sn = erab_item.ul_coun_tvalue.pdcp_sn;
+    rrc_log->info("Setting lcid=%d PDCP state to {Tx SN: %d, Rx SN: %d}\n",
+                  drb_it->lc_ch_id,
+                  drb_state.next_pdcp_tx_sn,
+                  drb_state.next_pdcp_rx_sn);
+    rrc_enb->pdcp->set_bearer_state(rrc_ue->rnti, drb_it->lc_ch_id, drb_state);
+  }
+
+  // Check if there is any pending Reconfiguration Complete. If there is, self-trigger
+  if (pending_recfg_complete.crit_exts.type().value != rrc_conn_recfg_complete_s::crit_exts_c_::types_opts::nulltype) {
+    trigger(pending_recfg_complete);
+    pending_recfg_complete.crit_exts.set(rrc_conn_recfg_complete_s::crit_exts_c_::types_opts::nulltype);
+  }
+}
+
+void rrc::ue::rrc_mobility::defer_recfg_complete(s1_target_ho_st& s, const recfg_complete_ev& ev)
+{
+  pending_recfg_complete = ev;
+}
+
 /*************************************************************************************************
  *                                  intraENB Handover sub-FSM
  ************************************************************************************************/
@@ -1277,7 +1292,8 @@ void rrc::ue::rrc_mobility::handle_crnti_ce(intraenb_ho_st& s, const user_crnti_
 
     rrc_ue->ue_security_cfg.regenerate_keys_handover(s.target_cell->cell_cfg.pci, s.target_cell->cell_cfg.dl_earfcn);
     rrc_ue->bearer_list.reest_bearers();
-    rrc_ue->bearer_list.apply_pdcp_bearer_updates(rrc_enb->pdcp, rrc_ue->ue_security_cfg);
+    rrc_ue->apply_pdcp_srb_updates();
+    rrc_ue->apply_pdcp_drb_updates();
   } else {
     rrc_log->info("Received duplicate C-RNTI CE during rnti=0x%x handover.\n", rrc_ue->rnti);
   }

srsenb/src/stack/rrc/rrc_ue.cc

@@ -271,8 +271,9 @@ void rrc::ue::send_connection_setup()
   mac_ctrl->handle_con_setup(setup);
 
   // Add SRBs/DRBs, and configure RLC+PDCP
-  bearer_list.apply_pdcp_bearer_updates(parent->pdcp, ue_security_cfg);
+  apply_pdcp_srb_updates();
-  bearer_list.apply_rlc_bearer_updates(parent->rlc);
+  apply_pdcp_drb_updates();
+  apply_rlc_rb_updates();
 
   // Configure PHY layer
   apply_setup_phy_config_dedicated(*phy_cfg); // It assumes SCell has not been set before
@@ -406,8 +407,9 @@ void rrc::ue::send_connection_reest()
   mac_ctrl->handle_con_reest(reest);
 
   // Add SRBs/DRBs, and configure RLC+PDCP
-  bearer_list.apply_pdcp_bearer_updates(parent->pdcp, ue_security_cfg);
+  apply_pdcp_srb_updates();
-  bearer_list.apply_rlc_bearer_updates(parent->rlc);
+  apply_pdcp_drb_updates();
+  apply_rlc_rb_updates();
 
   // Configure PHY layer
   apply_setup_phy_config_dedicated(*phy_cfg); // It assumes SCell has not been set before
@@ -536,8 +538,9 @@ void rrc::ue::send_connection_reconf(srslte::unique_byte_buffer_t pdu)
   apply_reconf_phy_config(*conn_reconf);
 
   // setup SRB2/DRBs in PDCP and RLC
-  bearer_list.apply_pdcp_bearer_updates(parent->pdcp, ue_security_cfg);
+  apply_pdcp_srb_updates();
-  bearer_list.apply_rlc_bearer_updates(parent->rlc);
+  apply_pdcp_drb_updates();
+  apply_rlc_rb_updates();
 
   // Add pending NAS info
   bearer_list.fill_pending_nas_info(conn_reconf);
@@ -642,8 +645,9 @@ void rrc::ue::send_connection_reconf_new_bearer()
   conn_reconf->rr_cfg_ded_present = bearer_list.fill_rr_cfg_ded(conn_reconf->rr_cfg_ded);
 
   // Setup new bearer
-  bearer_list.apply_pdcp_bearer_updates(parent->pdcp, ue_security_cfg);
+  apply_pdcp_srb_updates();
-  bearer_list.apply_rlc_bearer_updates(parent->rlc);
+  apply_pdcp_drb_updates();
+  apply_rlc_rb_updates();
   // Add pending NAS info
   bearer_list.fill_pending_nas_info(conn_reconf);
 
@@ -1394,6 +1398,59 @@ void rrc::ue::apply_reconf_phy_config(const asn1::rrc::rrc_conn_recfg_r8_ies_s&
   }
 }
 
+void rrc::ue::apply_pdcp_srb_updates()
+{
+  for (const srb_to_add_mod_s& srb : bearer_list.get_pending_addmod_srbs()) {
+    parent->pdcp->add_bearer(rnti, srb.srb_id, srslte::make_srb_pdcp_config_t(srb.srb_id, false));
+
+    // For SRB2, enable security/encryption/integrity
+    if (ue_security_cfg.is_as_sec_cfg_valid()) {
+      parent->pdcp->config_security(rnti, srb.srb_id, ue_security_cfg.get_as_sec_cfg());
+      parent->pdcp->enable_integrity(rnti, srb.srb_id);
+      parent->pdcp->enable_encryption(rnti, srb.srb_id);
+    }
+  }
+}
+
+void rrc::ue::apply_pdcp_drb_updates()
+{
+  for (uint8_t drb_id : bearer_list.get_pending_rem_drbs()) {
+    parent->pdcp->del_bearer(rnti, drb_id + 2);
+  }
+  for (const drb_to_add_mod_s& drb : bearer_list.get_pending_addmod_drbs()) {
+    // Configure DRB1 in PDCP
+    if (drb.pdcp_cfg_present) {
+      srslte::pdcp_config_t pdcp_cnfg_drb = srslte::make_drb_pdcp_config_t(drb.drb_id, false, drb.pdcp_cfg);
+      parent->pdcp->add_bearer(rnti, drb.lc_ch_id, pdcp_cnfg_drb);
+    } else {
+      srslte::pdcp_config_t pdcp_cnfg_drb = srslte::make_drb_pdcp_config_t(drb.drb_id, false);
+      parent->pdcp->add_bearer(rnti, drb.lc_ch_id, pdcp_cnfg_drb);
+    }
+
+    if (ue_security_cfg.is_as_sec_cfg_valid()) {
+      parent->pdcp->config_security(rnti, drb.lc_ch_id, ue_security_cfg.get_as_sec_cfg());
+      parent->pdcp->enable_integrity(rnti, drb.lc_ch_id);
+      parent->pdcp->enable_encryption(rnti, drb.lc_ch_id);
+    }
+  }
+}
+
+void rrc::ue::apply_rlc_rb_updates()
+{
+  for (const srb_to_add_mod_s& srb : bearer_list.get_pending_addmod_srbs()) {
+    parent->rlc->add_bearer(rnti, srb.srb_id, srslte::rlc_config_t::srb_config(srb.srb_id));
+  }
+  if (bearer_list.get_pending_rem_drbs().size() > 0) {
+    parent->rrc_log->error("Removing DRBs not currently supported\n");
+  }
+  for (const drb_to_add_mod_s& drb : bearer_list.get_pending_addmod_drbs()) {
+    if (not drb.rlc_cfg_present) {
+      parent->rrc_log->warning("Default RLC DRB config not supported\n");
+    }
+    parent->rlc->add_bearer(rnti, drb.lc_ch_id, srslte::make_rlc_config_t(drb.rlc_cfg));
+  }
+}
+
 int rrc::ue::get_cqi(uint16_t* pmi_idx, uint16_t* n_pucch, uint32_t ue_cc_idx)
 {
   cell_ctxt_dedicated* c = cell_ded_list.get_ue_cc_idx(ue_cc_idx);