Merge remote-tracking branch 'origin/nr_ue_epoch_target' into integration_2025_w48 (!3659)

UE NTN - Epoch time handling for Target cell

In case of Handover, NTNconfig sent in RRCreconfiguration triggering handover
contains epoch time wrt timing of Target cell. NTNconfig in RRC needs to be
processed only after timing is acquired on the target cell.

In case of Target cell, epoch time is the sfn nearest to the frame timing of the
target cell.

openair2/RRC/NR_UE/rrc_UE.c

@@ -210,7 +210,7 @@ static void get_epochtime_from_sib19scheduling(NR_UE_RRC_SI_INFO *SI_info, int *
         slot);
 }
 
-static int eval_epoch_time(NR_UE_RRC_SI_INFO *SI_info, NR_NTN_Config_r17_t *ntncfg, int frame)
+static int eval_epoch_time(NR_UE_RRC_SI_INFO *SI_info, NR_NTN_Config_r17_t *ntncfg, int frame, bool is_targetcell)
 {
   int epoch_frame = 0, epoch_subframe = 0;
   int diff_frames = 0;
@@ -229,11 +229,19 @@ static int eval_epoch_time(NR_UE_RRC_SI_INFO *SI_info, NR_NTN_Config_r17_t *ntnc
     ntncfg->epochTime_r17->sfn_r17 = epoch_frame;
     ntncfg->epochTime_r17->subFrameNR_r17 = epoch_subframe;
   }
-  // For serving cell, the field sfn indicates the current SFN or the next upcoming SFN
-  // after the frame where the message indicating the epochTime is received
-  // i.e. Epochframe can be present or future SFN
-  diff_frames = (epoch_frame - frame + 1024) % 1024;    // According to 38.331 Epochtime is defined for serving cell like this
-  LOG_I(NR_RRC, "Epoch frame %d, ahead by %d frames\n", epoch_frame, diff_frames);
+  if (is_targetcell) {
+    // For Target cell,the SFN nearest to the frame needs to be considered
+    // i.e. Epochframe can be in the past or future
+    int diff1 = (frame - epoch_frame + 1024) % 1024;
+    int diff2 = (epoch_frame - frame + 1024) % 1024;
+    diff_frames = (diff1 < diff2) ? -diff1 : diff2;
+  } else {
+    // For serving cell, the field sfn indicates the current SFN or the next upcoming SFN
+    // after the frame where the message indicating the epochTime is received
+    // i.e. Epochframe can be present or future SFN
+    diff_frames = (epoch_frame - frame + 1024) % 1024;    // According to 38.331 Epochtime is defined for serving cell like this
+  }
+  LOG_I(NR_RRC, "Epoch frame %d ahead by %d frames\n", epoch_frame, diff_frames);
   return diff_frames;
 }
 
@@ -257,11 +265,11 @@ static int get_ntn_timervalues(NR_UE_RRC_SI_INFO *SI_info, NR_NTN_Config_r17_t *
   return sib19_timer_ms;
 }
 
-static void nr_rrc_process_ntnconfig(NR_UE_RRC_INST_t *rrc, NR_UE_RRC_SI_INFO *SI_info, NR_NTN_Config_r17_t *ntncfg, int frame)
+static void nr_rrc_process_ntnconfig(NR_UE_RRC_INST_t *rrc, NR_UE_RRC_SI_INFO *SI_info, NR_NTN_Config_r17_t *ntncfg, int frame, bool is_targetcell)
 {
   SI_info->SInfo_r17.sib19_validity = true;
   // Check if Epochtime is sent or not
-  int diff_frames = eval_epoch_time(SI_info, ntncfg, frame);
+  int diff_frames = eval_epoch_time(SI_info, ntncfg, frame, is_targetcell);
 
   if (ntncfg->ntn_UlSyncValidityDuration_r17) { // ulsyncvalidity duration configured
     int val430_ms = 0, sib19_timer_ms = 0;
@@ -361,7 +369,7 @@ static void nr_decode_SI(NR_UE_RRC_SI_INFO *SI_info, NR_SystemInformation_t *si,
         sib19 = typeandinfo->choice.sib19_v1700;
         if (g_log->log_component[NR_RRC].level >= OAILOG_DEBUG)
           xer_fprint(stdout, &asn_DEF_NR_SIB19_r17, (const void *)sib19);
-        nr_rrc_process_ntnconfig(rrc, SI_info, sib19->ntn_Config_r17, frame);
+        nr_rrc_process_ntnconfig(rrc, SI_info, sib19->ntn_Config_r17, frame, false);
         break;
       default:
         break;
@@ -1454,6 +1462,11 @@ static void nr_rrc_ue_decode_NR_BCCH_BCH_Message(NR_UE_RRC_INST_t *rrc,
                                                  uint8_t *const bufferP,
                                                  const uint8_t buffer_len)
 {
+  // MIB received on the target cell. Now process target ntncfg once new timing is received.
+  if (phycellid == rrc->phyCellID && rrc->target_ntncfg) {
+    rrc->process_target_ntncfg = true;
+  }
+
   NR_BCCH_BCH_Message_t *bcch_message = NULL;
   rrc->phyCellID = phycellid;
   rrc->arfcn_ssb = ssb_arfcn;
@@ -1754,13 +1767,20 @@ static void nr_rrc_process_reconfigurationWithSync(NR_UE_RRC_INST_t *rrc,
 
   // 3GPP TS38.331 section 5.3.5.5.2
   nr_timer_stop(&tac->T430);
+
+  if (rrc->target_ntncfg) {
+    ASN_STRUCT_FREE(asn_DEF_NR_NTN_Config_r17, rrc->target_ntncfg);
+    rrc->target_ntncfg = NULL;
+    rrc->process_target_ntncfg = false;
+  }
   if (reconfigurationWithSync->spCellConfigCommon &&
       reconfigurationWithSync->spCellConfigCommon->ext2 &&
       reconfigurationWithSync->spCellConfigCommon->ext2->ntn_Config_r17) {
     NR_NTN_Config_r17_t *ntncfg = reconfigurationWithSync->spCellConfigCommon->ext2->ntn_Config_r17;
     // EPOCH time is always sent if NTN config is sent through DCCH
     AssertFatal(ntncfg->epochTime_r17, "NTN-CONFIG sent in dedicated mode should have EPOCHTIME\n");
-    nr_rrc_process_ntnconfig(rrc, &rrc->perNB[gNB_index].SInfo, ntncfg, rrc->current_frame);
+    const int copy_result = asn_copy(&asn_DEF_NR_NTN_Config_r17, (void **)&rrc->target_ntncfg, ntncfg);
+    AssertFatal(copy_result == 0, "unable to copy NR_NTN_Config_r17_t\n");
   }
 }
 
@@ -2626,6 +2646,13 @@ void *rrc_nrue(void *notUsed)
     nr_rrc_handle_timers(rrc);
     NR_UE_RRC_SI_INFO *SInfo = &rrc->perNB[NRRRC_FRAME_PROCESS(msg_p).gnb_id].SInfo;
     nr_rrc_SI_timers(SInfo);
+    if (rrc->process_target_ntncfg) {
+      // Process target NTNCFG as the target cells timing is acquired
+      nr_rrc_process_ntnconfig(rrc, &rrc->perNB[NRRRC_FRAME_PROCESS(msg_p).gnb_id].SInfo, rrc->target_ntncfg, rrc->current_frame, true);
+      ASN_STRUCT_FREE(asn_DEF_NR_NTN_Config_r17, rrc->target_ntncfg);
+      rrc->target_ntncfg = NULL;
+      rrc->process_target_ntncfg = false;
+    }
     break;
 
   case NR_RRC_MAC_INAC_IND:
@@ -2806,6 +2833,14 @@ static void nr_rrc_initiate_rrcReestablishment(NR_UE_RRC_INST_t *rrc, NR_Reestab
       set_DRB_status(rrc, i, RB_SUSPENDED);
     }
   }
+
+  // Free Target NTNcfg is stored
+  if (rrc->target_ntncfg) {
+    ASN_STRUCT_FREE(asn_DEF_NR_NTN_Config_r17, rrc->target_ntncfg);
+    rrc->target_ntncfg = NULL;
+    rrc->process_target_ntncfg = false;
+  }
+
   // release the MCG SCell(s), if configured
   // no SCell configured in our implementation
 
@@ -2996,6 +3031,13 @@ void nr_rrc_going_to_IDLE(NR_UE_RRC_INST_t *rrc,
     asn1cFreeStruc(asn_DEF_NR_UE_TimersAndConstants, tac->sib1_TimersAndConstants);
   }
 
+  // Free Target NTNcfg is stored
+  if (rrc->target_ntncfg) {
+    ASN_STRUCT_FREE(asn_DEF_NR_NTN_Config_r17, rrc->target_ntncfg);
+    rrc->target_ntncfg = NULL;
+    rrc->process_target_ntncfg = false;
+  }
+
   // reset MAC
   NR_UE_MAC_reset_cause_t cause = (rrc->nrRrcState == RRC_STATE_DETACH_NR) ? DETACH : GO_TO_IDLE;
   nr_mac_rrc_message_t rrc_msg = {0};

openair2/RRC/NR_UE/rrc_defs.h

@@ -268,6 +268,8 @@ typedef struct NR_UE_RRC_INST_s {
   NR_SL_PreconfigurationNR_r16_t *sl_preconfig;
   // NTN params
   bool is_NTN_UE;
+  NR_NTN_Config_r17_t *target_ntncfg;
+  bool process_target_ntncfg;
   notifiedFIFO_t *mac_input_nf;
 } NR_UE_RRC_INST_t;