DU: trigger UE Context Modification Required and handle

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c

@@ -43,6 +43,7 @@
 #include "UTIL/OPT/opt.h"
 
 #include "openair2/LAYER2/nr_rlc/nr_rlc_oai_api.h"
+#include "F1AP_CauseRadioNetwork.h"
 
 #include "RRC/NR/MESSAGES/asn1_msg.h"
 
@@ -2995,3 +2996,24 @@ void nr_mac_check_ul_failure(const gNB_MAC_INST *nrmac, int rnti, NR_UE_sched_ct
     nrmac->mac_rrc.ue_context_release_request(&request);
   }
 }
+
+void nr_mac_trigger_reconfiguration(const gNB_MAC_INST *nrmac, const NR_UE_info_t *UE)
+{
+  DevAssert(UE->CellGroup != NULL);
+  uint8_t buf[2048];
+  asn_enc_rval_t enc_rval = uper_encode_to_buffer(&asn_DEF_NR_CellGroupConfig, NULL, UE->CellGroup, buf, sizeof(buf));
+  AssertFatal(enc_rval.encoded > 0, "ASN1 encoding of CellGroupConfig failed, failed type %s\n", enc_rval.failed_type->name);
+  du_to_cu_rrc_information_t du2cu = {
+    .cellGroupConfig = buf,
+    .cellGroupConfig_length = (enc_rval.encoded + 7) >> 3,
+  };
+  f1_ue_data_t ue_data = du_get_f1_ue_data(UE->rnti);
+  f1ap_ue_context_modif_required_t required = {
+    .gNB_CU_ue_id = ue_data.secondary_ue,
+    .gNB_DU_ue_id = UE->rnti,
+    .du_to_cu_rrc_information = &du2cu,
+    .cause = F1AP_CAUSE_RADIO_NETWORK,
+    .cause_value = F1AP_CauseRadioNetwork_action_desirable_for_radio_reasons,
+  };
+  nrmac->mac_rrc.ue_context_modification_required(&required);
+}

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -225,7 +225,6 @@ static int nr_process_mac_pdu(instance_t module_idP,
           if (ra->state >= WAIT_Msg3 && ra->rnti == UE->rnti) {
             ra->crnti = ((pduP[1]&0xFF)<<8)|(pduP[2]&0xFF);
             ra->state = Msg3_dcch_dtch;
-            LOG_I(NR_MAC, "Received UL_SCH_LCID_C_RNTI with C-RNTI 0x%04x\n", ra->crnti);
             break;
           }
         }
@@ -786,6 +785,7 @@ static void _nr_rx_sdu(const module_id_t gnb_mod_idP,
                 // Let's abort the current RA, so the UE will trigger a new RA later but using RRCSetupRequest instead. A better solution may be implemented
                 mac_remove_nr_ue(gNB_mac, ra->rnti);
                 nr_clear_ra_proc(gnb_mod_idP, CC_idP, frameP, ra);
+		LOG_W(NR_MAC, "No UE found with C-RNTI %04x, ignoring Msg.3 to have UE come back with new RA attempt\n", ra->crnti);
                 return;
               } else {
                 // The UE identified by C-RNTI still exists at the gNB
@@ -794,9 +794,11 @@ static void _nr_rx_sdu(const module_id_t gnb_mod_idP,
                 // Reset HARQ processes
                 reset_dl_harq_list(&UE_C->UE_sched_ctrl);
                 reset_ul_harq_list(&UE_C->UE_sched_ctrl);
+
+                // Trigger RRC Reconfiguration
+                LOG_I(NR_MAC, "Received UL_SCH_LCID_C_RNTI with C-RNTI 0x%04x, triggering RRC Reconfiguration\n", UE_C->rnti);
+                nr_mac_trigger_reconfiguration(RC.nrmac[gnb_mod_idP], UE_C);
               }
-              LOG_I(NR_MAC, "Activating scheduling response to MSG3 with DCCH/DTCCH and RNTI 0x%04x (state %d)\n",
-                    ra->crnti, ra->state);
             }
             else {
               LOG_I(NR_MAC, "Activating scheduling RA-Msg4 for TC_RNTI 0x%04x (state %d)\n",

openair2/LAYER2/NR_MAC_gNB/mac_proto.h

@@ -447,4 +447,6 @@ void nr_mac_trigger_ul_failure(NR_UE_sched_ctrl_t *sched_ctrl, NR_SubcarrierSpac
 void nr_mac_reset_ul_failure(NR_UE_sched_ctrl_t *sched_ctrl);
 void nr_mac_check_ul_failure(const gNB_MAC_INST *nrmac, int rnti, NR_UE_sched_ctrl_t *sched_ctrl);
 
+void nr_mac_trigger_reconfiguration(const gNB_MAC_INST *nrmac, const NR_UE_info_t *UE);
+
 #endif /*__LAYER2_NR_MAC_PROTO_H__*/

openair2/LAYER2/NR_MAC_gNB/mac_rrc_dl_handler.c

@@ -25,6 +25,7 @@
 #include "openair2/F1AP/f1ap_ids.h"
 #include "openair2/LAYER2/nr_rlc/nr_rlc_oai_api.h"
 #include "openair2/RRC/NR/MESSAGES/asn1_msg.h"
+#include "F1AP_CauseRadioNetwork.h"
 
 #include "uper_decoder.h"
 #include "uper_encoder.h"
@@ -245,14 +246,59 @@ void ue_context_modification_request(const f1ap_ue_context_modif_req_t *req)
 
 void ue_context_modification_confirm(const f1ap_ue_context_modif_confirm_t *confirm)
 {
-  (void) confirm;
-  AssertFatal(false, "%s() not implemented yet\n", __func__);
+  LOG_I(MAC, "Received UE Context Modification Confirm for UE %04x\n", confirm->gNB_DU_ue_id);
+
+  gNB_MAC_INST *mac = RC.nrmac[0];
+  NR_SCHED_LOCK(&mac->sched_lock);
+  /* check first that the scheduler knows such UE */
+  NR_UE_info_t *UE = find_nr_UE(&mac->UE_info, confirm->gNB_DU_ue_id);
+  if (UE == NULL) {
+    LOG_E(MAC, "ERROR: unknown UE with RNTI %04x, ignoring UE Context Modification Confirm\n", confirm->gNB_DU_ue_id);
+    NR_SCHED_UNLOCK(&mac->sched_lock);
+    return;
+  }
+  NR_SCHED_UNLOCK(&mac->sched_lock);
+
+  if (confirm->rrc_container_length > 0)
+    nr_rlc_srb_recv_sdu(confirm->gNB_DU_ue_id, DCCH, confirm->rrc_container, confirm->rrc_container_length);
+
+  /* nothing else to be done? */
 }
 
 void ue_context_modification_refuse(const f1ap_ue_context_modif_refuse_t *refuse)
 {
-  (void) refuse;
-  AssertFatal(false, "%s() not implemented yet\n", __func__);
+  /* Currently, we only use the UE Context Modification Required procedure to
+   * trigger a RRC reconfigurtion after Msg.3 with C-RNTI MAC CE. If the CU
+   * refuses, it cannot do this reconfiguration, leaving the UE in an
+   * unconfigured state. Therefore, we just free all RA-related info, and
+   * request the release of the UE.  */
+  LOG_W(MAC, "Received UE Context Modification Refuse for %04x, requesting release\n", refuse->gNB_DU_ue_id);
+
+  gNB_MAC_INST *mac = RC.nrmac[0];
+  NR_SCHED_LOCK(&mac->sched_lock);
+  NR_UE_info_t *UE = find_nr_UE(&RC.nrmac[0]->UE_info, refuse->gNB_DU_ue_id);
+  if (UE == NULL) {
+    LOG_E(MAC, "ERROR: unknown UE with RNTI %04x, ignoring UE Context Modification Refuse\n", refuse->gNB_DU_ue_id);
+    NR_SCHED_UNLOCK(&mac->sched_lock);
+    return;
+  }
+
+  const int CC_id = 0;
+  NR_COMMON_channels_t *cc = &mac->common_channels[CC_id];
+  for (int i = 0; i < NR_NB_RA_PROC_MAX; i++) {
+    NR_RA_t *ra = &cc->ra[i];
+    if (ra->crnti == UE->rnti)
+      nr_clear_ra_proc(0, CC_id, 0 /* frame */, ra);
+  }
+  NR_SCHED_UNLOCK(&mac->sched_lock);
+
+  f1ap_ue_context_release_req_t request = {
+    .gNB_CU_ue_id = refuse->gNB_CU_ue_id,
+    .gNB_DU_ue_id = refuse->gNB_DU_ue_id,
+    .cause = F1AP_CAUSE_RADIO_NETWORK,
+    .cause_value = F1AP_CauseRadioNetwork_procedure_cancelled,
+  };
+  mac->mac_rrc.ue_context_release_request(&request);
 }
 
 void ue_context_release_command(const f1ap_ue_context_release_cmd_t *cmd)