Sending Initial Context Setup Response after RRC reconfiguration.

lib/include/srsran/interfaces/enb_s1ap_interfaces.h

@@ -59,8 +59,9 @@ public:
   virtual bool user_release(uint16_t rnti, asn1::s1ap::cause_radio_network_e cause_radio) = 0;
   virtual bool is_mme_connected()                                                         = 0;
 
-  /// TS 36.413, 8.3.1 - Initial Context Setup
+  // Notify S1AP of RRC reconfiguration successful finish.
-  virtual void ue_ctxt_setup_complete(uint16_t rnti) = 0;
+  // Many S1AP procedures use this notification to indicate successful end (e.g InitialContextSetupRequest)
+  virtual void notify_rrc_reconf_complete(uint16_t rnti) = 0;
 
   /**
    * Command the s1ap to transmit a HandoverRequired message to MME.

srsenb/hdr/stack/s1ap/s1ap.h

@@ -80,7 +80,7 @@ public:
   bool user_exists(uint16_t rnti) override;
   void user_mod(uint16_t old_rnti, uint16_t new_rnti) override;
   bool user_release(uint16_t rnti, asn1::s1ap::cause_radio_network_e cause_radio) override;
-  void ue_ctxt_setup_complete(uint16_t rnti) override;
+  void notify_rrc_reconf_complete(uint16_t rnti) override;
   bool is_mme_connected() override;
   bool send_ho_required(uint16_t                     rnti,
                         uint32_t                     target_eci,
@@ -168,6 +168,8 @@ private:
   bool handle_erabreleasecommand(const asn1::s1ap::erab_release_cmd_s& msg);
   bool handle_uecontextmodifyrequest(const asn1::s1ap::ue_context_mod_request_s& msg);
 
+  void ue_ctxt_setup_complete(uint16_t rnti);
+
   // handover
   /**
    * Source eNB Handler for S1AP "HANDOVER PREPARATION FAILURE" Message
@@ -247,6 +249,7 @@ private:
                                uint32_t                              m_tmsi = 0,
                                uint8_t                               mmec   = 0);
     void ue_ctxt_setup_complete();
+    void notify_rrc_reconf_complete();
     bool send_erab_setup_response(const erab_id_list& erabs_setup, const erab_item_list& erabs_failed);
     bool send_erab_release_response(const erab_id_list& erabs_released, const erab_item_list& erabs_failed);
     bool send_erab_modify_response(const erab_id_list& erabs_modified, const erab_item_list& erabs_failed);

srsenb/src/stack/rrc/rrc_ue.cc

@@ -332,9 +332,7 @@ void rrc::ue::parse_ul_dcch(uint32_t lcid, srsran::unique_byte_buffer_t pdu)
       break;
     case ul_dcch_msg_type_c::c1_c_::types::ue_cap_info:
       if (handle_ue_cap_info(&ul_dcch_msg.msg.c1().ue_cap_info())) {
-        parent->s1ap->ue_ctxt_setup_complete(rnti);
         send_connection_reconf(std::move(pdu));
-        state = RRC_STATE_WAIT_FOR_CON_RECONF_COMPLETE;
       } else {
         send_connection_reject(procedure_result_code::none);
         state = RRC_STATE_IDLE;
@@ -475,7 +473,6 @@ void rrc::ue::handle_rrc_con_setup_complete(rrc_conn_setup_complete_s* msg, srsr
   } else {
     parent->s1ap->initial_ue(rnti, enb_cc_idx, s1ap_cause, std::move(pdu));
   }
-  state = RRC_STATE_WAIT_FOR_CON_RECONF_COMPLETE;
 
   // 2> if the UE has radio link failure or handover failure information available
   if (msg->crit_exts.type().value == c1_or_crit_ext_opts::c1 and
@@ -828,6 +825,9 @@ void rrc::ue::handle_rrc_reconf_complete(rrc_conn_recfg_complete_s* msg, srsran:
     rlf_info_pending = false;
     send_ue_info_req();
   }
+
+  // Many S1AP procedures end with RRC Reconfiguration. Notify S1AP accordingly.
+  parent->s1ap->notify_rrc_reconf_complete(rnti);
 }
 
 void rrc::ue::send_ue_info_req()

srsenb/src/stack/s1ap/s1ap.cc

@@ -452,6 +452,15 @@ void s1ap::ue_ctxt_setup_complete(uint16_t rnti)
   u->ue_ctxt_setup_complete();
 }
 
+void s1ap::notify_rrc_reconf_complete(uint16_t rnti)
+{
+  ue* u = users.find_ue_rnti(rnti);
+  if (u == nullptr) {
+    return;
+  }
+  u->notify_rrc_reconf_complete();
+}
+
 bool s1ap::is_mme_connected()
 {
   return mme_connected;
@@ -1461,6 +1470,17 @@ bool s1ap::ue::send_uectxtreleasecomplete()
   return s1ap_ptr->sctp_send_s1ap_pdu(tx_pdu, ctxt.rnti, "UEContextReleaseComplete");
 }
 
+void s1ap::ue::notify_rrc_reconf_complete()
+{
+  if (current_state == s1ap_elem_procs_o::init_msg_c::types_opts::init_context_setup_request) {
+    logger.info("Procedure %s,rnti=0x%x - Received RRC reconf complete. Finishing UE context setup.",
+                s1ap_elem_procs_o::init_msg_c::types_opts{current_state}.to_string(),
+                ctxt.rnti);
+    ue_ctxt_setup_complete();
+    return;
+  }
+}
+
 void s1ap::ue::ue_ctxt_setup_complete()
 {
   if (current_state != s1ap_elem_procs_o::init_msg_c::types_opts::init_context_setup_request) {
@@ -1510,7 +1530,7 @@ void s1ap::ue::ue_ctxt_setup_complete()
   // Log event.
   event_logger::get().log_s1_ctx_create(ctxt.enb_cc_idx, ctxt.mme_ue_s1ap_id.value(), ctxt.enb_ue_s1ap_id, ctxt.rnti);
 
-  s1ap_ptr->sctp_send_s1ap_pdu(tx_pdu, ctxt.rnti, "E-RABSetupResponse");
+  s1ap_ptr->sctp_send_s1ap_pdu(tx_pdu, ctxt.rnti, "InitialContextSetupResponse");
 }
 
 bool s1ap::ue::send_erab_setup_response(const erab_id_list& erabs_setup, const erab_item_list& erabs_failed)

srsenb/test/common/dummy_classes.h

@@ -104,7 +104,7 @@ public:
   void write_pdu(uint16_t rnti, srsran::unique_byte_buffer_t pdu) override {}
   bool user_exists(uint16_t rnti) override { return true; }
   bool user_release(uint16_t rnti, asn1::s1ap::cause_radio_network_e cause_radio) override { return true; }
-  void ue_ctxt_setup_complete(uint16_t rnti) override {}
+  void notify_rrc_reconf_complete(uint16_t rnti) override {}
   bool is_mme_connected() override { return true; }
   bool send_ho_required(uint16_t                     rnti,
                         uint32_t                     target_eci,

srsenb/test/s1ap/s1ap_test.cc

@@ -185,7 +185,7 @@ void add_rnti(s1ap& s1ap_obj, mme_dummy& mme)
                        0x40, 0x0a, 0x0a, 0x1f, 0x7f, 0x00, 0x01, 0x01, 0x00, 0x00, 0x00, 0x01};
   cbref             = asn1::cbit_ref(icsresp, sizeof(icsresp));
   TESTASSERT(s1ap_pdu.unpack(cbref) == SRSRAN_SUCCESS);
-  s1ap_obj.ue_ctxt_setup_complete(0x46);
+  s1ap_obj.notify_rrc_reconf_complete(0x46);
   sdu = mme.read_msg();
   TESTASSERT(sdu->N_bytes > 0);
   cbref = asn1::cbit_ref{sdu->msg, sdu->N_bytes};