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NR UE: improve NTN reestablishment by continuing with previous HFN

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This commit is contained in:
Thomas Schlichter
2025-12-19 16:42:55 +01:00
parent 30afbc41a6
commit f6fd7b61ec
1 changed files with 21 additions and 8 deletions
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executables/nr-ue.c
+21 -8
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@@ -736,6 +736,10 @@ static inline int get_readBlockSize(uint16_t slot, NR_DL_FRAME_PARMS *fp) {
static void fix_ntn_epoch_hfn(PHY_VARS_NR_UE *UE, int hfn, int frame)
{
if (!UE->nrUE_config.ntn_config.is_targetcell)
return;
UE->nrUE_config.ntn_config.is_targetcell = false;
const int epoch_frame = UE->nrUE_config.ntn_config.epoch_sfn;
const int diff1 = (frame - epoch_frame + 1024) % 1024;
const int diff2 = (epoch_frame - frame + 1024) % 1024;
@@ -1057,22 +1061,31 @@ void *UE_thread(void *arg)
// we have the decoded frame index in the return of the synch process
// and we shifted above to the first slot of next frame
decoded_frame_rx = (decoded_frame_rx + 1) % MAX_FRAME_NUMBER;
const int prev_frame_rx = (absolute_slot / nb_slot_frame) % MAX_FRAME_NUMBER;
const int prev_hfn_rx = (absolute_slot / nb_slot_frame) / MAX_FRAME_NUMBER;
int decoded_hfn_rx = prev_hfn_rx;
if (decoded_frame_rx <= prev_frame_rx)
decoded_hfn_rx++;
// we do ++ first in the regular processing, so it will be begin of frame;
absolute_slot = decoded_frame_rx * nb_slot_frame - 1;
absolute_slot = (decoded_hfn_rx * MAX_FRAME_NUMBER + decoded_frame_rx) * nb_slot_frame - 1;
if (UE->sl_mode == 2) {
// Set to the slot where the SL-SSB was decoded
absolute_slot += UE->SL_UE_PHY_PARAMS.sync_params.slot_offset;
}
// With the correct frame and slot numbers, we can now fix the UL timing
const int frame_rx = (absolute_slot / nb_slot_frame) % 1024;
const int hfn_rx = (absolute_slot / nb_slot_frame) / 1024;
fix_ntn_epoch_hfn(UE, hfn_rx, frame_rx);
UE->nrUE_config.ntn_config.is_targetcell = false;
fix_ntn_epoch_hfn(UE, decoded_hfn_rx, decoded_frame_rx);
if (UE->nrUE_config.ntn_config.params_changed) {
apply_ntn_config(UE, fp, hfn_rx, frame_rx, 0, &duration_rx_to_tx, &timing_advance, &ntn_koffset, &ntn_targetcell);
apply_ntn_config(UE,
fp,
decoded_hfn_rx,
decoded_frame_rx,
0,
&duration_rx_to_tx,
&timing_advance,
&ntn_koffset,
&ntn_targetcell);
} else {
const int mu = fp->numerology_index;
const int abs_subframe_tx = 10240 * hfn_rx + 10 * frame_rx + (duration_rx_to_tx >> mu);
const int abs_subframe_tx = (absolute_slot + 1 + duration_rx_to_tx) / fp->slots_per_subframe;
apply_ntn_timing_advance_and_doppler(UE, fp, abs_subframe_tx);
ntn_targetcell = false;
}