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NR UE: allow the epochTime-r17 in NTN-Config-r17 to be in the future

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The implementation is limited to epoch times that are not more than 5.12 seconds in the future (allowed are up to 10.24 seconds)
and ntn-UlSyncValidityDuration < 5.12 seconds (allowed are up to 90 seconds).

To fix this limitation, the hyper frame number HFN has to be introduced at the OAI UE!
This commit is contained in:
Thomas Schlichter
2025-06-20 11:24:06 +00:00
parent a9a6ab367b
commit 960f2e7101
1 changed files with 9 additions and 1 deletions
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executables/nr-ue.c
+9 -1
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@@ -927,7 +927,15 @@ static inline void apply_ntn_config(PHY_VARS_NR_UE *UE,
const int abs_subframe_tx = 10 * frame_rx + ((slot_rx + *duration_rx_to_tx) >> mu);
const int abs_subframe_epoch =
10 * UE->ntn_config_message->ntn_config_params.epoch_sfn + UE->ntn_config_message->ntn_config_params.epoch_subframe;
const int ms_since_epoch = (abs_subframe_tx - abs_subframe_epoch + 10240) % 10240;
int ms_since_epoch = abs_subframe_tx - abs_subframe_epoch;
// cope with sfn wrap-around
// this currently limits us to epoch times that are not more than 5.12 seconds in the future (allowed are up to 10.24 seconds)
// and ntn-UlSyncValidityDuration < 5.12 seconds (allowed are up to 900 seconds)
// TODO: fix this limitation by introducing the hyper frame number HFN
if (ms_since_epoch < -5120)
ms_since_epoch += 10240;
else if (ms_since_epoch > 5120)
ms_since_epoch -= 10240;
const double total_ta_ms = UE->ntn_config_message->ntn_config_params.ntn_total_time_advance_ms;
const double total_ta_drift = UE->ntn_config_message->ntn_config_params.ntn_total_time_advance_drift; // µs/s