Add telnet trigger for N2 handover

* the command gets in input the neighbour PCI and the UE ID
* the telnet ci function to retrieve the UE context was extended in the process
* add function to trigger handover on the same gNB for testing purposes

Co-authored-by: batuhan duyuler <batuhan.duyuler@firecell.io>

common/utils/telnetsrv/telnetsrv_ci.c

@@ -38,6 +38,7 @@
 #include "openair2/LAYER2/nr_rlc/nr_rlc_ue_manager.h"
 #include "openair2/LAYER2/nr_rlc/nr_rlc_entity_am.h"
 #include "openair2/LAYER2/NR_MAC_gNB/mac_proto.h"
+#include "openair2/RRC/NR/rrc_gNB_mobility.h"
 
 #define TELNETSERVERCODE
 #include "telnetsrv.h"
@@ -196,6 +197,53 @@ int rrc_gNB_trigger_f1_ho(char *buf, int debug, telnet_printfunc_t prnt)
   return 0;
 }
 
+extern void nr_HO_N2_trigger_telnet(gNB_RRC_INST *rrc, uint32_t neighbour_pci, uint32_t rrc_ue_id);
+
+/** @brief Trigger N2 handover for UE
+ *  @param buf: Neighbour PCI, SCell PCI, RRC UE ID
+ *  @param debug: Debug flag
+ *  @param prnt: Print function
+ *  @return 0 on success, -1 on failure */
+int rrc_gNB_trigger_n2_ho(char *buf, int debug, telnet_printfunc_t prnt)
+{
+  if (!RC.nrrrc)
+    ERROR_MSG_RET("no RRC present, cannot list counts\n");
+
+  if (!buf) {
+    ERROR_MSG_RET("Please provide neighbour cell id and ue id\n");
+  } else {
+    // Parse neighbour cell PCI
+    char *token = strtok(buf, ",");
+    if (!token) {
+      ERROR_MSG_RET("Invalid input. Expected format: Neighbour PCI, ueId\n");
+    }
+    uint32_t neighbour_pci = strtol(token, NULL, 10);
+
+    // Parse ueId
+    token = strtok(NULL, ",");
+    if (!token) {
+      ERROR_MSG_RET("Missing UE ID\n");
+    }
+    uint32_t ueId = strtol(token, NULL, 10);
+
+    // Retrieve UE context
+    rrc_gNB_ue_context_t *ue_p = rrc_gNB_get_ue_context(RC.nrrrc[0], ueId);
+    if (!ue_p) {
+      ERROR_MSG_RET("UE with id %u not found\n", ueId);
+    }
+    gNB_RRC_UE_t *UE = &ue_p->ue_context;
+
+    // Trigger N2 handover
+    nr_HO_N2_trigger_telnet(RC.nrrrc[0], neighbour_pci, UE->rrc_ue_id);
+
+    // Print success message
+    prnt("RRC N2 handover triggered for UE %u with neighbour cell id %u\n",
+         ueId,
+         neighbour_pci);
+  }
+  return 0;
+}
+
 int force_ul_failure(char *buf, int debug, telnet_printfunc_t prnt)
 {
   if (!RC.nrmac)
@@ -245,6 +293,7 @@ static telnetshell_cmddef_t cicmds[] = {
     {"trigger_f1_ho", "[rrc_ue_id(int,opt)]", rrc_gNB_trigger_f1_ho},
     {"fetch_du_by_ue_id", "[rrc_ue_id(int,opt)]", fetch_du_by_ue_id},
     {"get_current_bwp", "[rnti(hex,opt)]", get_current_bwp},
+    {"trigger_n2_ho", "[neighbour_pci(uint32_t),ueId(uint32_t)]", rrc_gNB_trigger_n2_ho},
     {"", "", NULL},
 };
 

openair2/RRC/NR/rrc_gNB_mobility.c

@@ -549,3 +549,52 @@ void nr_rrc_trigger_n2_ho(gNB_RRC_INST *rrc,
   rrc_gNB_send_NGAP_HANDOVER_REQUIRED(rrc, ue, neighbour_config, hoPrepInfo);
   free_byte_array(hoPrepInfo);
 }
+
+extern const nr_neighbour_cell_t *get_neighbour_cell_by_pci(const neighbour_cell_configuration_t *cell, int pci);
+extern const neighbour_cell_configuration_t *get_neighbour_cell_config(const gNB_RRC_INST *rrc, int cell_id);
+
+void nr_HO_N2_trigger_telnet(gNB_RRC_INST *rrc, uint32_t neighbour_pci, uint32_t rrc_ue_id)
+{
+  rrc_gNB_ue_context_t *ue_context_p = rrc_gNB_get_ue_context(rrc, rrc_ue_id);
+  if (ue_context_p == NULL) {
+    LOG_E(NR_RRC, "N2 HO trigger failed for UE %d: cannot find UE context\n", rrc_ue_id);
+    return;
+  }
+  gNB_RRC_UE_t *UE = &ue_context_p->ue_context;
+
+  struct nr_rrc_du_container_t *du = get_du_for_ue(rrc, rrc_ue_id);
+  if (du == NULL) {
+    LOG_E(NR_RRC, "N2 HO trigger failed for UE %d: Unknown DU\n", rrc_ue_id);
+    return;
+  }
+  uint16_t scell_pci = du->setup_req->cell[0].info.nr_pci;
+
+  // Simulate handover on the same cell (testing purposes)
+  if (neighbour_pci == scell_pci) {
+    LOG_I(NR_RRC, "UE %d: trigger handover on the same cell PCI=%d\n", rrc_ue_id, neighbour_pci);
+    nr_neighbour_cell_t neighbourConfig = {
+        .isIntraFrequencyNeighbour = true,
+        .gNB_ID = du->setup_req->gNB_DU_id,
+        .nrcell_id = du->setup_req->cell[0].info.nr_cellid,
+        .physicalCellId = du->setup_req->cell[0].info.nr_pci,
+        .plmn = du->setup_req->cell[0].info.plmn,
+        .subcarrierSpacing = du->setup_req->cell[0].info.tdd.tbw.scs,
+    };
+    nr_rrc_trigger_n2_ho(rrc, UE, neighbour_pci, &neighbourConfig);
+    return;
+  }
+
+  const f1ap_served_cell_info_t *scell_du = get_cell_information_by_phycellId(scell_pci);
+  DevAssert(scell_du);
+  LOG_I(NR_RRC, "UE %d: triggered N2 HO, source PCI=%d to target PCI=%d\n", rrc_ue_id, scell_pci, neighbour_pci);
+
+  const neighbour_cell_configuration_t *cell = get_neighbour_cell_config(rrc, scell_du->nr_cellid);
+  const nr_neighbour_cell_t *neighbour = get_neighbour_cell_by_pci(cell, neighbour_pci);
+
+  if (neighbour == NULL) {
+    LOG_E(NR_RRC, "N2 HO trigger failed for UE %d: could not find neighbour cell with PCI=%d\n", rrc_ue_id, neighbour_pci);
+    return;
+  }
+
+  nr_rrc_trigger_n2_ho(rrc, UE, scell_du->nr_pci, neighbour);
+}