Handle successful HO after reconfigurationComplete

The HO is completed (from a pure RAN perspective) when receiving
reconfiguration complete. In that case, remove the HO context, and
signal successful handover through the callback. For the F1 handover,
this means releasing the UE at the source DU.
Co-authored-by: batuhanduyuler <batuhan.duyuler@firecell.io>
Co-authored-by: rmagueta <rmagueta@allbesmart.pt>

openair2/RRC/NR/rrc_gNB.c

@@ -1558,6 +1558,14 @@ static void handle_rrcReconfigurationComplete(gNB_RRC_INST *rrc, gNB_RRC_UE_t *U
       LOG_I(RRC, "UE %d: transaction %d still ongoing for action %d\n", UE->rrc_ue_id, i, UE->xids[i]);
     }
   }
+
+  if (UE->ho_context != NULL) {
+    LOG_A(NR_RRC, "handover for UE %d/RNTI %04x complete!\n", UE->rrc_ue_id, UE->rnti);
+    DevAssert(UE->ho_context->target != NULL);
+
+    UE->ho_context->target->ho_success(rrc, UE);
+    nr_rrc_finalize_ho(UE);
+  }
 }
 
 static void rrc_gNB_generate_UECapabilityEnquiry(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue)

openair2/RRC/NR/rrc_gNB_mobility.c

@@ -272,6 +272,24 @@ static void nr_rrc_f1_ho_acknowledge(gNB_RRC_INST *rrc, gNB_RRC_UE_t *UE, uint8_
   }
 }
 
+static void nr_rrc_f1_ho_complete(gNB_RRC_INST *rrc, gNB_RRC_UE_t *UE)
+{
+  DevAssert(UE->ho_context != NULL);
+  nr_ho_source_cu_t *source_ctx = UE->ho_context->source;
+  DevAssert(source_ctx != NULL);
+  RETURN_IF_INVALID_ASSOC_ID(source_ctx->du->assoc_id);
+  f1ap_ue_context_release_cmd_t cmd = {
+      .gNB_CU_ue_id = UE->rrc_ue_id,
+      .gNB_DU_ue_id = source_ctx->du_ue_id,
+      .cause = F1AP_CAUSE_RADIO_NETWORK, // better
+      .cause_value = 5, // 5 = F1AP_CauseRadioNetwork_interaction_with_other_procedure
+      .srb_id = DCCH,
+  };
+  rrc->mac_rrc.ue_context_release_command(source_ctx->du->assoc_id, &cmd);
+  LOG_I(NR_RRC, "UE %d Handover: trigger release on DU assoc_id %d\n", UE->rrc_ue_id, source_ctx->du->assoc_id);
+}
+
+
 void nr_rrc_trigger_f1_ho(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue, nr_rrc_du_container_t *source_du, nr_rrc_du_container_t *target_du)
 {
   DevAssert(rrc != NULL);
@@ -287,11 +305,17 @@ void nr_rrc_trigger_f1_ho(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue, nr_rrc_du_contain
   // and therefore also the PDU sessions. Orig RRC reconfiguration should be in
   // handover preparation information
   ho_req_ack_t ack = nr_rrc_f1_ho_acknowledge;
-  ho_success_t success = NULL;
+  ho_success_t success = nr_rrc_f1_ho_complete;
   ho_cancel_t cancel = NULL;
   nr_initiate_handover(rrc, ue, source_du, target_du, buf, size, ack, success, cancel);
 }
 
+void nr_rrc_finalize_ho(gNB_RRC_UE_t *ue)
+{
+  free_ho_ctx(ue->ho_context);
+  ue->ho_context = NULL;
+}
+
 void nr_HO_F1_trigger_telnet(gNB_RRC_INST *rrc, uint32_t rrc_ue_id)
 {
   rrc_gNB_ue_context_t *ue_context_p = rrc_gNB_get_ue_context(rrc, rrc_ue_id);

openair2/RRC/NR/rrc_gNB_mobility.h

@@ -67,5 +67,6 @@ typedef struct nr_handover_context_s {
 } nr_handover_context_t;
 
 void nr_rrc_trigger_f1_ho(gNB_RRC_INST *rrc, gNB_RRC_UE_t *ue, nr_rrc_du_container_t *source_du, nr_rrc_du_container_t *target_du);
+void nr_rrc_finalize_ho(gNB_RRC_UE_t *ue);
 
 #endif /* RRC_GNB_MOBILITY_H_ */