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NR UE: introduce orbit propagation to improve N_UE_TA_adj accuracy

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Instead of trying to estimate N_UE_TA_adj with a second degree polynomial,
we introduce orbit propagation to calculate N_UE_TA_adj with higher accuracy.

When we receive the satellite ephemeris data consisting of the satellite position vector
and the satellite velocity vector, we calculate parameters for orbit propagation, assuming
a circular orbit in the plane created by the satellite position vector and the satellite
velocity vector. This is done in the function prepare_ue_sat_ta().

Every millisecond, we use these parameters together with the time since epoch to calculate
the satellite position on that orbit and from this the reound-trip-time between UE and the
satellite, what corresponds to N_UE_TA_adj. This is done in the function apply_ntn_timing_advance().
This commit is contained in:
Thomas Schlichter
2025-11-19 10:05:45 +01:00
committed by francescomani
parent 43722e6bac
commit 59af5e4ad2
8 changed files with 121 additions and 93 deletions
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openair1/SCHED_NR_UE/fapi_nr_ue_l1.c
+10 -3
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@@ -98,10 +98,17 @@ static void configure_ntn_params(PHY_VARS_NR_UE *ue, fapi_nr_dl_ntn_config_comma
ue->ntn_config_message->ntn_config_params.epoch_hfn = ntn_params_message->epoch_hfn;
ue->ntn_config_message->ntn_config_params.epoch_sfn = ntn_params_message->epoch_sfn;
ue->ntn_config_message->ntn_config_params.epoch_subframe = ntn_params_message->epoch_subframe;
ue->ntn_config_message->ntn_config_params.omega = ntn_params_message->omega;
ue->ntn_config_message->ntn_config_params.pos_sat_0 = ntn_params_message->pos_sat_0;
ue->ntn_config_message->ntn_config_params.pos_sat_90 = ntn_params_message->pos_sat_90;
ue->ntn_config_message->ntn_config_params.N_common_ta_adj = ntn_params_message->N_common_ta_adj;
ue->ntn_config_message->ntn_config_params.N_common_ta_drift = ntn_params_message->N_common_ta_drift;
ue->ntn_config_message->ntn_config_params.N_common_ta_drift_variant = ntn_params_message->N_common_ta_drift_variant;
ue->ntn_config_message->ntn_config_params.cell_specific_k_offset = ntn_params_message->cell_specific_k_offset;
ue->ntn_config_message->ntn_config_params.ntn_total_time_advance_ms = ntn_params_message->ntn_total_time_advance_ms;
ue->ntn_config_message->ntn_config_params.ntn_total_time_advance_drift = ntn_params_message->ntn_total_time_advance_drift;
ue->ntn_config_message->ntn_config_params.ntn_total_time_advance_drift_variant = ntn_params_message->ntn_total_time_advance_drift_variant;
ue->ntn_config_message->update = true;
}