gNB-CU sends the ue_context_modification_request to the source gNB-DU with the...

gNB-CU sends the ue_context_modification_request to the source gNB-DU with the TransmissionActionIndicator and RRCReconfiguration. This RRC Reconfiguration is sent to the UE.

openair2/COMMON/f1ap_messages_types.h

@@ -497,6 +497,7 @@ typedef struct f1ap_ue_context_setup_s {
   ReconfigurationCompl_t ReconfigComplOutcome;
   uint8_t *rrc_container;
   int      rrc_container_length;
+  uint8_t *transmission_action_indicator;
 } f1ap_ue_context_setup_t, f1ap_ue_context_modif_req_t, f1ap_ue_context_modif_resp_t;
 
 typedef enum F1ap_Cause_e {

openair2/F1AP/f1ap_cu_ue_context_management.c

@@ -1023,12 +1023,12 @@ int CU_send_UE_CONTEXT_MODIFICATION_REQUEST(sctp_assoc_t assoc_id, f1ap_ue_conte
 
   /* optional */
   /* c7. TransmissionActionIndicator */
-  if (0) {
+  if (f1ap_ue_context_modification_req->transmission_action_indicator != NULL) {
     asn1cSequenceAdd(out->protocolIEs.list, F1AP_UEContextModificationRequestIEs_t, ie7);
     ie7->id                                     = F1AP_ProtocolIE_ID_id_TransmissionActionIndicator;
     ie7->criticality                            = F1AP_Criticality_ignore;
     ie7->value.present                          = F1AP_UEContextModificationRequestIEs__value_PR_TransmissionActionIndicator;
-    ie7->value.choice.TransmissionActionIndicator = F1AP_TransmissionActionIndicator_stop;
+    ie7->value.choice.TransmissionActionIndicator = *f1ap_ue_context_modification_req->transmission_action_indicator;
   }
 
   /* optional */

openair2/F1AP/f1ap_du_ue_context_management.c

@@ -1030,6 +1030,7 @@ int DU_handle_UE_CONTEXT_MODIFICATION_REQUEST(instance_t instance, sctp_assoc_t
     /* correct here */
     if ( ieRRC->value.choice.RRCContainer.size )  {
       f1ap_ue_context_modification_req->rrc_container = malloc(ieRRC->value.choice.RRCContainer.size);
+      f1ap_ue_context_modification_req->rrc_container_length = ieRRC->value.choice.RRCContainer.size;
       memcpy(f1ap_ue_context_modification_req->rrc_container,
           ieRRC->value.choice.RRCContainer.buf, ieRRC->value.choice.RRCContainer.size);
       f1ap_ue_context_modification_req->rrc_container_length = ieRRC->value.choice.RRCContainer.size;
@@ -1066,6 +1067,19 @@ int DU_handle_UE_CONTEXT_MODIFICATION_REQUEST(instance_t instance, sctp_assoc_t
     }
   }
 
+  /* TransmissionActionIndicator */
+  F1AP_UEContextModificationRequestIEs_t *ieTxInd;
+  F1AP_FIND_PROTOCOLIE_BY_ID(F1AP_UEContextModificationRequestIEs_t,
+                             ieTxInd,
+                             container,
+                             F1AP_ProtocolIE_ID_id_TransmissionActionIndicator,
+                             false);
+
+  if (ieTxInd) {
+    f1ap_ue_context_modification_req->transmission_action_indicator = calloc(1, sizeof(uint8_t));
+    *f1ap_ue_context_modification_req->transmission_action_indicator = ieTxInd->value.choice.TransmissionActionIndicator;
+  }
+
   ue_context_modification_request(f1ap_ue_context_modification_req);
   return 0;
 }

openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c

@@ -26,6 +26,7 @@
 #include "openair2/F1AP/f1ap_common.h"
 #include "openair2/LAYER2/nr_rlc/nr_rlc_oai_api.h"
 #include "F1AP_CauseRadioNetwork.h"
+#include "NR_HandoverCommand.h"
 #include "openair3/ocp-gtpu/gtp_itf.h"
 #include "openair2/LAYER2/nr_pdcp/nr_pdcp_oai_api.h"
 
@@ -544,8 +545,32 @@ void ue_context_modification_request(const f1ap_ue_context_modif_req_t *req)
 
   if (req->rrc_container != NULL) {
     logical_chan_id_t id = 1;
+
+    NR_HandoverCommand_t *ho_command = NULL;
+    asn_dec_rval_t dec_rval = uper_decode(NULL,
+                                          &asn_DEF_NR_HandoverCommand,
+                                          (void **)&ho_command,
+                                          req->rrc_container,
+                                          req->rrc_container_length,
+                                          0,
+                                          0);
+
+    if (dec_rval.code == RC_OK && ho_command->criticalExtensions.present == NR_HandoverCommand__criticalExtensions_PR_c1
+        && ho_command->criticalExtensions.choice.c1->present == NR_HandoverCommand__criticalExtensions__c1_PR_handoverCommand) {
+
+      if (LOG_DEBUGFLAG(DEBUG_ASN1)) {
+        xer_fprint(stdout, &asn_DEF_NR_HandoverCommand, ho_command);
+      }
+      OCTET_STRING_t *handoverCommandMessage =
+          &ho_command->criticalExtensions.choice.c1->choice.handoverCommand->handoverCommandMessage;
+
+      // handoverCommandMessage->buf contains the RRCReconfiguration
+      nr_rlc_srb_recv_sdu(req->gNB_DU_ue_id, id, handoverCommandMessage->buf, handoverCommandMessage->size);
+      nr_mac_enable_ue_rrc_processing_timer(mac, UE, UE->apply_cellgroup);
+    } else {
       nr_rlc_srb_recv_sdu(req->gNB_DU_ue_id, id, req->rrc_container, req->rrc_container_length);
     }
+  }
 
   if (req->ReconfigComplOutcome != RRCreconf_info_not_present && req->ReconfigComplOutcome != RRCreconf_success) {
     LOG_E(NR_MAC,

openair2/RRC/NR/MESSAGES/asn1_msg.c

@@ -80,6 +80,7 @@
 #include "NR_PCCH-Message.h"
 #include "NR_PagingRecord.h"
 #include "NR_UE-CapabilityRequestFilterNR.h"
+#include "NR_HandoverCommand.h"
 #include "common/utils/nr/nr_common.h"
 #if defined(NR_Rel16)
   #include "NR_SCS-SpecificCarrier.h"
@@ -1372,3 +1373,25 @@ int do_NR_Paging(uint8_t Mod_id, uint8_t *buffer, uint32_t tmsi)
 
   return((enc_rval.encoded+7)/8);
 }
+
+int16_t do_NR_HandoverCommand(uint8_t *ho_buf, int16_t ho_size, uint8_t *rrc_buffer, int16_t rrc_size)
+{
+  NR_HandoverCommand_t *ho_command = calloc(1, sizeof(NR_HandoverCommand_t));
+  ho_command->criticalExtensions.present = NR_HandoverCommand__criticalExtensions_PR_c1;
+  ho_command->criticalExtensions.choice.c1 = calloc(1, sizeof(struct NR_HandoverCommand__criticalExtensions__c1));
+  ho_command->criticalExtensions.choice.c1->present = NR_HandoverCommand__criticalExtensions__c1_PR_handoverCommand;
+  ho_command->criticalExtensions.choice.c1->choice.handoverCommand = calloc(1, sizeof(struct NR_HandoverCommand_IEs));
+
+  AssertFatal(OCTET_STRING_fromBuf(&ho_command->criticalExtensions.choice.c1->choice.handoverCommand->handoverCommandMessage,
+                                   (char *)rrc_buffer, rrc_size) != -1, "fatal: OCTET_STRING_fromBuf failed\n");
+
+  if (LOG_DEBUGFLAG(DEBUG_ASN1)) {
+    xer_fprint(stdout, &asn_DEF_NR_HandoverCommand, ho_command);
+  }
+
+  asn_enc_rval_t enc_rval = uper_encode_to_buffer(&asn_DEF_NR_HandoverCommand, NULL, ho_command, ho_buf, ho_size);
+
+  AssertFatal(enc_rval.encoded > 0, "ASN1 message encoding failed (%s, %lu)!\n", enc_rval.failed_type->name, enc_rval.encoded);
+
+  return ((enc_rval.encoded + 7) / 8);
+}

openair2/RRC/NR/MESSAGES/asn1_msg.h

@@ -106,6 +106,8 @@ int do_RRCReconfiguration(const gNB_RRC_UE_t *UE,
                           struct NR_RRCReconfiguration_v1530_IEs__dedicatedNAS_MessageList *dedicatedNAS_MessageList,
                           NR_CellGroupConfig_t *cellGroupConfig);
 
+int16_t do_NR_HandoverCommand(uint8_t *ho_buf, int16_t ho_size, uint8_t *rrc_buffer, int16_t rrc_size);
+
 int do_RRCSetupComplete(uint8_t *buffer,
                         size_t buffer_size,
                         const uint8_t Transaction_id,

openair2/RRC/NR/rrc_gNB.c

@@ -192,6 +192,15 @@ static void rrc_deliver_dl_rrc_message(void *deliver_pdu_data, ue_id_t ue_id, in
   data->rrc->mac_rrc.dl_rrc_message_transfer(data->assoc_id, data->dl_rrc);
 }
 
+static void nr_rrc_prepare_protected_rrc_message(void *deliver_pdu_data, ue_id_t ue_id, int srb_id, char *buf, int size, int sdu_id)
+{
+  DevAssert(deliver_pdu_data != NULL);
+  deliver_dl_rrc_message_data_t *data = (deliver_dl_rrc_message_data_t *)deliver_pdu_data;
+  data->dl_rrc->rrc_container_length = size;
+  memcpy(data->dl_rrc->rrc_container, buf, size);
+  DevAssert(data->dl_rrc->srb_id == srb_id);
+}
+
 void nr_rrc_transfer_protected_rrc_message(const gNB_RRC_INST *rrc,
                                            const gNB_RRC_UE_t *ue_p,
                                            uint8_t srb_id,
@@ -692,7 +701,7 @@ void rrc_gNB_generate_dedicatedRRCReconfiguration(const protocol_ctxt_t *const c
 
   NR_CellGroupConfig_t *cellGroupConfig = ue_p->masterCellGroup;
 
-  const nr_rrc_du_container_t *du = get_du_for_ue(rrc, ue_p->rrc_ue_id);
+  nr_rrc_du_container_t *du = get_du_for_ue(rrc, ue_p->rrc_ue_id);
   DevAssert(du != NULL);
   f1ap_served_cell_info_t *cell_info = &du->setup_req->cell[0].info;
   NR_MeasConfig_t *measconfig = NULL;
@@ -747,7 +756,43 @@ void rrc_gNB_generate_dedicatedRRCReconfiguration(const protocol_ctxt_t *const c
         ctxt_pP->module_id,
         DCCH);
 
+  if (ue_p->StatusRrc == NR_RRC_HO_EXECUTION) {
+    f1_ue_data_t ue_data = cu_get_f1_ue_data(ue_p->rrc_ue_id);
+    uint8_t rrc_container[RRC_BUF_SIZE] = {0};
+    f1ap_dl_rrc_message_t dl_rrc = {.gNB_CU_ue_id = ue_p->rrc_ue_id, .gNB_DU_ue_id = ue_data.secondary_ue, .srb_id = DCCH, .rrc_container = rrc_container};
+    deliver_dl_rrc_message_data_t data = {.rrc = rrc, .dl_rrc = &dl_rrc, .assoc_id = ue_data.du_assoc_id};
+    nr_pdcp_data_req_srb(ue_p->rrc_ue_id,
+                         DCCH,
+                         rrc_gNB_mui++,
+                         size,
+                         (unsigned char *const)buffer,
+                         nr_rrc_prepare_protected_rrc_message,
+                         &data);
+
+
+    uint8_t ho_buffer[RRC_BUF_SIZE] = {0};
+    int16_t ho_size = do_NR_HandoverCommand(ho_buffer, RRC_BUF_SIZE, data.dl_rrc->rrc_container, data.dl_rrc->rrc_container_length);
+
+    uint8_t transmission_action_indicator = 0;
+
+    RETURN_IF_INVALID_ASSOC_ID(ue_data);
+    f1ap_ue_context_modif_req_t ue_context_modif_req = {
+        .gNB_CU_ue_id = ue_p->rrc_ue_id,
+        .gNB_DU_ue_id = ue_data.secondary_ue,
+        .plmn.mcc = rrc->configuration.mcc[0],
+        .plmn.mnc = rrc->configuration.mnc[0],
+        .plmn.mnc_digit_length = rrc->configuration.mnc_digit_length[0],
+        .nr_cellid = rrc->nr_cellid,
+        .servCellId = 0, // TODO: correct value?
+        .ReconfigComplOutcome = RRCreconf_success,
+        .transmission_action_indicator = &transmission_action_indicator,
+        .rrc_container_length = ho_size,
+        .rrc_container = ho_buffer,
+    };
+    rrc->mac_rrc.ue_context_modification_request(ue_data.du_assoc_id, &ue_context_modif_req);
+  } else {
     nr_rrc_transfer_protected_rrc_message(rrc, ue_p, DCCH, buffer, size);
+  }
 }
 
 //-----------------------------------------------------------------------------