Paging (RRC): refactor NGAP Paging handler in CUCP

RRC now builds F1AP paging messages directly by calling F1AP/direct
callbacks and aligning the CU/DU intergace with the F1AP design in the CU.
Messages are forwarded based on TAI-based cell matching across DUs.

- Remove F1AP_PAGING_IND message def and f1ap_paging_ind_t.
  RRC no longer sends ITTI F1AP_PAGING_IND; it builds f1ap_paging_t
  and passes it to the DU path.

- rrc_gNB_process_PAGING_IND: new signature (rrc, instance, msg)
  with const where appropriate; call in rrc_gnb_task() updated.

- NGAP handler logic: For each TAI, match (PLMN + TAC) to
  rrc->configuration; collect matching TAIs. Build one f1ap_paging_t
  (5G-S-TMSI via nr_construct_5g_s_tmsi(), identity type
  F1AP_PAGING_IDENTITY_CN_UE, optional drx/priority/origin copied
  from ngap_paging_ind_t), call rrc_send_paging_to_dus(), then
  free_f1ap_paging(). Remove the previous AssertFatal stub, CC loop,
  NODE_IS_CU branch, and UE lookup logic: it is now handled by
  F1AP/direct CU callbacks.

- rrc_gNB_du: Add rrc_send_paging_to_dus(rrc, tais, n_tai, msg).
  Iterate DUs with RB_FOREACH; for each DU, fill msg->cells from
  du->cells whose (PLMN + TAC) matches any requested TAI, set
  n_cells, then call rrc->mac_rrc.paging_transfer(du->assoc_id,
  msg). Skip DUs with no matching cells. Prevents duplicate paging
  when multiple TAIs map to the same PLMN.

openair2/COMMON/f1ap_messages_def.h

@@ -65,4 +65,3 @@ MESSAGE_DEF(F1AP_UE_CONTEXT_MODIFICATION_REFUSE, MESSAGE_PRIORITY_MED, f1ap_ue_c
 
 /* CU -> DU*/
 MESSAGE_DEF(F1AP_PAGING, MESSAGE_PRIORITY_MED, f1ap_paging_t, f1ap_paging)
-MESSAGE_DEF(F1AP_PAGING_IND, MESSAGE_PRIORITY_MED, f1ap_paging_ind_t, f1ap_paging_ind)

openair2/COMMON/f1ap_messages_types.h

@@ -68,7 +68,6 @@
 #define F1AP_UE_CONTEXT_RELEASE_CMD(mSGpTR)        (mSGpTR)->ittiMsg.f1ap_ue_context_release_cmd
 #define F1AP_UE_CONTEXT_RELEASE_COMPLETE(mSGpTR)   (mSGpTR)->ittiMsg.f1ap_ue_context_release_complete
 
-#define F1AP_PAGING_IND(mSGpTR)                    (mSGpTR)->ittiMsg.f1ap_paging_ind
 #define F1AP_PAGING(mSGpTR)                        (mSGpTR)->ittiMsg.f1ap_paging
 
 /* Length of the transport layer address string
@@ -633,15 +632,6 @@ typedef struct f1ap_ue_context_rel_cplt_t {
   uint32_t gNB_DU_ue_id;
 } f1ap_ue_context_rel_cplt_t;
 
-typedef struct f1ap_paging_ind_s {
-  uint16_t ueidentityindexvalue;
-  uint64_t fiveg_s_tmsi;
-  uint8_t  fiveg_s_tmsi_length;
-  plmn_id_t plmn;
-  uint64_t nr_cellid;
-  uint8_t  paging_drx;
-} f1ap_paging_ind_t;
-
 typedef struct f1ap_paging_cell_item_s {
   plmn_id_t plmn;
   uint64_t nr_cellid;

openair2/RRC/NR/rrc_gNB.c

@@ -3523,7 +3523,7 @@ void *rrc_gnb_task(void *args_p) {
         break;
 
       case NGAP_PAGING_IND:
-        rrc_gNB_process_PAGING_IND(msg_p, instance);
+        rrc_gNB_process_PAGING_IND(RC.nrrrc[instance], instance, &NGAP_PAGING_IND(msg_p));
         break;
 
       case NGAP_HANDOVER_REQUEST:

openair2/RRC/NR/rrc_gNB_NGAP.c

@@ -84,6 +84,7 @@
 #include "nr_pdcp/nr_pdcp_oai_api.h"
 #include "oai_asn1.h"
 #include "openair2/F1AP/f1ap_ids.h"
+#include "openair2/F1AP/lib/f1ap_paging.h"
 #include "openair3/SECU/key_nas_deriver.h"
 #include "rrc_messages_types.h"
 #include "s1ap_messages_types.h"
@@ -1629,57 +1630,67 @@ int rrc_gNB_process_NGAP_PDUSESSION_RELEASE_COMMAND(ngap_pdusession_release_comm
   return 0;
 }
 
-int rrc_gNB_process_PAGING_IND(MessageDef *msg_p, instance_t instance)
+/** @brief Handle NGAP Paging Indication from the AMF.
+ *  For each TAI in the message, matches (PLMN + TAC) against the gNB configuration; on match,
+ *  builds an F1AP Paging message and distributes it to all DUs that serve cells in that PLMN. */
+int rrc_gNB_process_PAGING_IND(gNB_RRC_INST *rrc, const instance_t instance, const ngap_paging_ind_t *msg)
 {
-  ngap_paging_ind_t *msg = &NGAP_PAGING_IND(msg_p);
+  DevAssert(rrc);
-  for (uint16_t tai_idx = 0; tai_idx < msg->n_tai; tai_idx++) {
+  DevAssert(msg);
-    nr_tai_t *tai = &msg->tai_list[tai_idx];
+
-    plmn_id_t *p = &tai->plmn;
+  // Construct 5G-S-TMSI from paging identity components
-    LOG_I(NR_RRC,
+  const fiveg_s_tmsi_t *s_tmsi = &msg->ue_paging_identity.s_tmsi;
-          "[gNB %ld] TAI List for Paging: MCC=%03d, MNC=%0*d, TAC=%d\n",
+  const uint64_t fiveg_s_tmsi = nr_construct_5g_s_tmsi(s_tmsi->amf_set_id, s_tmsi->amf_pointer, s_tmsi->m_tmsi);
+  const nr_rrc_config_t *req = &rrc->configuration;
+  DevAssert(req->num_plmn > 0);
+
+  LOG_D(NR_RRC, "[gNB %ld] Processing NGAP Paging Indication for %d TAIs\n", instance, msg->n_tai);
+
+  // Paging Attempt Information (TS 38.413 §9.3.1.72, TS 38.300 §9.2.5)
+  // AMF provides attempt count and intended attempts for paging optimization (area expansion, retransmission logic).
+  if (msg->paging_attempt_info != NULL) {
+    LOG_D(NR_RRC,
+          "[gNB %ld] Paging Attempt Count: %u, Intended Number of Attempts: %u\n",
           instance,
-          p->mcc,
+          msg->paging_attempt_info->paging_attempt_count,
-          p->mnc_digit_length,
+          msg->paging_attempt_info->intended_paging_attempts);
-          p->mnc,
+  }
-          tai->tac);
+
-    nr_rrc_config_t *req = &RC.nrrrc[instance]->configuration;
+  if (msg->n_tai > NGAP_MAX_NO_TAI_PAGING) {
-    for (uint8_t j = 0; j < req->num_plmn; j++) {
+    LOG_E(NR_RRC,
-      plmn_id_t *req_plmn = &req->plmn[j];
+          "[gNB %ld] Paging message error: n_tai (%d) exceeds NGAP_MAX_NO_TAI_PAGING (%d)\n",
-      if (req_plmn->mcc == p->mcc && req_plmn->mnc == p->mnc && req->tac == tai->tac) {
+          instance,
-        for (uint8_t CC_id = 0; CC_id < MAX_NUM_CCs; CC_id++) {
+          msg->n_tai,
-          AssertFatal(false, "to be implemented properly\n");
+          NGAP_MAX_NO_TAI_PAGING);
-          if (NODE_IS_CU(RC.nrrrc[instance]->node_type)) {
+    return -1;
-            MessageDef *m = itti_alloc_new_message(TASK_RRC_GNB, 0, F1AP_PAGING_IND);
+  }
-            F1AP_PAGING_IND(m).plmn = *req_plmn;
+
-            // Construct 5G-S-TMSI-Part1 from paging identity to find UE
+  // Build F1AP paging message once for all TAIs
-            const fiveg_s_tmsi_t *s_tmsi = &msg->ue_paging_identity.s_tmsi;
+  f1ap_paging_t f1ap_msg = {0};
-            uint64_t s_tmsi_part1 = nr_construct_5g_s_tmsi_part1(s_tmsi->amf_set_id, s_tmsi->amf_pointer, s_tmsi->m_tmsi);
+  f1ap_msg.ue_identity_index_value = s_tmsi->m_tmsi % 1024;
-            // Try to find UE by 5G-S-TMSI-Part1
+  f1ap_msg.identity_type = F1AP_PAGING_IDENTITY_CN_UE;
-            rrc_gNB_ue_context_t *ue_context_p = rrc_gNB_ue_context_5g_s_tmsi_exist(RC.nrrrc[instance], s_tmsi_part1);
+  f1ap_msg.identity.cn_ue_paging_identity = fiveg_s_tmsi;
-            if (ue_context_p == NULL) {
+  if (msg->paging_drx != NULL) {
-              LOG_W(NR_RRC, "UE not found by paging identity\n");
+    /* Mapping 1:1 between NGAP and F1AP Paging DRX */
-              return -1;
+    f1ap_msg.drx = malloc_or_fail(sizeof(*f1ap_msg.drx));
-            }
+    *f1ap_msg.drx = (f1ap_paging_drx_t)*msg->paging_drx;
-            // UE found: use its associated cell
+  }
-            gNB_RRC_UE_t *UE = &ue_context_p->ue_context;
+  if (msg->paging_priority != NULL) {
-            nr_rrc_cell_container_t *cell = rrc_get_pcell_for_ue(RC.nrrrc[instance], UE);
+    /* Mapping 1:1 between NGAP and F1AP Paging Priority */
-            if (cell == NULL) {
+    f1ap_msg.priority = malloc_or_fail(sizeof(*f1ap_msg.priority));
-              LOG_W(NR_RRC, "UE %d (rnti %04x) found by paging identity but has no valid cell\n", UE->rrc_ue_id, UE->rnti);
+    *f1ap_msg.priority = (f1ap_paging_priority_t)*msg->paging_priority;
-              return -1;
+  }
-            }
+  if (msg->origin != NULL) {
-            F1AP_PAGING_IND(m).nr_cellid = cell->info.cell_id;
+    /* Mapping 1:1 between NGAP and F1AP Paging Origin */
-            F1AP_PAGING_IND(m).ueidentityindexvalue = (uint16_t)(msg->ue_paging_identity.s_tmsi.m_tmsi % 1024);
+    f1ap_msg.origin = malloc_or_fail(sizeof(*f1ap_msg.origin));
-            F1AP_PAGING_IND(m).fiveg_s_tmsi = msg->ue_paging_identity.s_tmsi.m_tmsi;
+    *f1ap_msg.origin = (f1ap_paging_origin_t)*msg->origin;
-            F1AP_PAGING_IND(m).paging_drx = msg->paging_drx ? (uint8_t)*msg->paging_drx : 0;
+  }
-            LOG_E(F1AP, "ueidentityindexvalue %u fiveg_s_tmsi %ld paging_drx %u\n", F1AP_PAGING_IND (m).ueidentityindexvalue, F1AP_PAGING_IND (m).fiveg_s_tmsi, F1AP_PAGING_IND (m).paging_drx);
+
-            itti_send_msg_to_task(TASK_CU_F1, instance, m);
+  // For each DU, collect cells matching any AMF TAI (PLMN+TAC) and send
-          } else {
+  // one Paging with that cell list.
-            //rrc_gNB_generate_pcch_msg(NGAP_PAGING_IND(msg_p).ue_paging_identity.s_tmsi.m_tmsi,(uint8_t)NGAP_PAGING_IND(msg_p).paging_drx, instance, CC_id);
+  rrc_send_paging_to_dus(rrc, msg->tai_list, msg->n_tai, &f1ap_msg);
-          } // end of nodetype check
+
-        } // end of cc loop
+  free_f1ap_paging(&f1ap_msg);
-      } // end of mcc mnc check
-    } // end of num_plmn
-  } // end of tai size
 
   return 0;
 }

openair2/RRC/NR/rrc_gNB_NGAP.h

@@ -84,7 +84,7 @@ void rrc_gNB_send_NGAP_PDUSESSION_RELEASE_RESPONSE(gNB_RRC_INST *rrc, gNB_RRC_UE
 
 void nr_rrc_pdcp_config_security(gNB_RRC_UE_t *UE, bool enable_ciphering);
 
-int rrc_gNB_process_PAGING_IND(MessageDef *msg_p, instance_t instance);
+int rrc_gNB_process_PAGING_IND(gNB_RRC_INST *rrc, const instance_t instance, const ngap_paging_ind_t *msg);
 
 void rrc_gNB_send_NGAP_HANDOVER_REQUIRED(gNB_RRC_INST *rrc,
                                          gNB_RRC_UE_t *UE,

openair2/RRC/NR/rrc_gNB_du.c

@@ -820,3 +820,71 @@ void trigger_f1_reset(gNB_RRC_INST *rrc, sctp_assoc_t du_assoc_id)
   };
   rrc->mac_rrc.f1_reset(du_assoc_id, &reset);
 }
+
+/** @brief Distribute paging to DUs serving cells matching any of the requested TAIs.
+ *  Loops DUs once, collects matching cells per DU, sends one message per DU.
+ *  Each cell is added at most once per DU (cells are unique by cell_id within a DU).
+ *  Per 3GPP TS 23.003, TAI is uniquely identified by (PLMN, TAC) combination.
+ *  @param rrc RRC instance
+ *  @param tais Array of TAIs (PLMN + TAC) to match against
+ *  @param n_tai Number of TAIs in the array (must be > 0)
+ *  @param msg Pre-filled F1AP paging message */
+void rrc_send_paging_to_dus(gNB_RRC_INST *rrc, const nr_tai_t tais[], uint8_t n_tai, f1ap_paging_t *msg)
+{
+  DevAssert(msg && !msg->cells);
+  DevAssert(n_tai > 0);
+
+  nr_rrc_du_container_t *du = NULL;
+  // Loop over DUs once, for each DU, collects matching cells
+  RB_FOREACH (du, rrc_du_tree, &rrc->dus) {
+    RETURN_IF_INVALID_ASSOC_ID(du->assoc_id);
+
+    // Stack-allocated cell list for this DU iteration
+    f1ap_paging_cell_item_t cells[F1AP_MAX_NB_CELLS] = {0};
+    msg->cells = cells;
+    msg->n_cells = 0;
+
+    // For each cell in this DU, check if it matches any of the matching TAIs
+    FOR_EACH_SEQ_ARR (nr_rrc_cell_container_t **, cell, &du->cells) {
+      if (msg->n_cells >= F1AP_MAX_NB_CELLS) {
+        LOG_W(F1AP,
+              "[gNB] Paging: DU assoc_id %d has more than %d matching cells, skipping next cells\n",
+              du->assoc_id,
+              F1AP_MAX_NB_CELLS);
+        break;
+      }
+
+      const nr_rrc_cell_info_t *info = &(*cell)->info;
+      const plmn_id_t *cell_plmn = &info->plmn;
+      const uint16_t cell_tac = info->tac;
+      // Check if this cell's TAI (PLMN + TAC) matches any of the matching TAIs
+      for (uint8_t j = 0; j < n_tai; j++) {
+        const nr_tai_t *req_tai = &tais[j];
+        const plmn_id_t *req_plmn = &req_tai->plmn;
+        const uint16_t req_tac = req_tai->tac;
+        if (cell_plmn->mcc == req_plmn->mcc && cell_plmn->mnc == req_plmn->mnc
+            && cell_plmn->mnc_digit_length == req_plmn->mnc_digit_length && cell_tac == req_tac) {
+          f1ap_paging_cell_item_t *paging_cell = &msg->cells[msg->n_cells++];
+          paging_cell->plmn = *cell_plmn;
+          paging_cell->nr_cellid = info->cell_id;
+          break; // Found match, no need to check other TAIs
+        }
+      }
+    }
+
+    // Skip DUs with no matching cells
+    if (msg->n_cells == 0)
+      continue;
+    DevAssert(msg->n_cells <= F1AP_MAX_NB_CELLS);
+    LOG_I(F1AP,
+          "[gNB] Paging transfer to DU assoc_id %d: ue_identity_index_value=%u, paging_identity=%lu, n_cells=%u\n",
+          du->assoc_id,
+          msg->ue_identity_index_value,
+          msg->identity.cn_ue_paging_identity,
+          msg->n_cells);
+    // Send one message to the DU with all matching cells
+    rrc->mac_rrc.paging_transfer(du->assoc_id, msg);
+  }
+
+  msg->cells = NULL; // Stack allocation, no need to free
+}

openair2/RRC/NR/rrc_gNB_du.h

@@ -34,6 +34,9 @@ struct nr_rrc_cell_container_t;
 struct f1ap_gnb_du_configuration_update_s;
 struct f1ap_served_cell_info_t;
 
+#include "f1ap_messages_types.h"
+#include "ngap_messages_types.h"
+
 void rrc_gNB_process_f1_setup_req(struct f1ap_setup_req_s *req, sctp_assoc_t assoc_id);
 void rrc_CU_process_f1_lost_connection(struct gNB_RRC_INST_s *rrc, struct f1ap_lost_connection_t *lc, sctp_assoc_t assoc_id);
 void rrc_gNB_process_f1_du_configuration_update(struct f1ap_gnb_du_configuration_update_s *conf_up, sctp_assoc_t assoc_id);
@@ -58,4 +61,6 @@ struct nr_rrc_du_container_t *find_target_du(struct gNB_RRC_INST_s *rrc, sctp_as
 
 void trigger_f1_reset(struct gNB_RRC_INST_s *rrc, sctp_assoc_t du_assoc_id);
 
+void rrc_send_paging_to_dus(struct gNB_RRC_INST_s *rrc, const nr_tai_t tais[], uint8_t n_tai, f1ap_paging_t *f1ap_msg);
+
 #endif /* RRC_GNB_DU_H_ */