maki/openairinterface5g
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

NR UE NTN: consider acceleration on orbital path to calculate N_UE_TA_drift_variant

Browse Source 
The acceleration magnitude on the orbital path can be calculated as:

t = 2 * pi * r / v
omega = 2 * pi / t = v / r
acceleration = omega² * r = v² / r

Where t is the orbital period, r is the orbital radius, v is the orbital velocity, omega is the angular velocity.
The acceleration direction is from the SAT position towards the earth center.
To calculate the acceleration towards the UE, this is projected on the direction from the SAT to the UE.
This commit is contained in:
Thomas Schlichter
2025-08-09 07:37:35 +02:00
parent 05f9c975ee
commit eb6c195c9b
3 changed files with 23 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
openair2/LAYER2/NR_MAC_UE/config_ue.c
+15 -2
View File
@@ -289,8 +289,17 @@ static void calculate_ue_sat_ta(const position_t *position_params,
// calculate SAT velocity towards UE
double velocity = (vel_sat.X * dir_sat_ue.X + vel_sat.Y * dir_sat_ue.Y + vel_sat.Z * dir_sat_ue.Z) / distance;
// calculate SAT acceleration towards UE
const double radius_2 = pos_sat.X * pos_sat.X + pos_sat.Y * pos_sat.Y + pos_sat.Z * pos_sat.Z;
const double vel_sat_2 = vel_sat.X * vel_sat.X + vel_sat.Y * vel_sat.Y + vel_sat.Z * vel_sat.Z;
const double acceleration =
-(pos_sat.X * dir_sat_ue.X + pos_sat.Y * dir_sat_ue.Y + pos_sat.Z * dir_sat_ue.Z) * vel_sat_2 / (radius_2 * distance);
LOG_D(NR_MAC, "Satellite velocity towards UE: %f m/s, acceleration towards UE: %f m/s²\n", velocity, acceleration);
ntn_ta->N_UE_TA_adj = (2 * distance / SPEED_OF_LIGHT) * 1e3; // in ms
ntn_ta->N_UE_TA_drift = (2 * -velocity / SPEED_OF_LIGHT) * 1e6; // in µs/s
ntn_ta->N_UE_TA_drift_variant = (2 * acceleration / SPEED_OF_LIGHT) * 1e6; // in µs/s²
}
// populate ntn_ta structure from mac
@@ -321,10 +330,12 @@ static void configure_ntn_ta(module_id_t module_id,
LOG_W(NR_MAC, "NR UE currently supports only ephemerisInfo_r17 of type positionVelocity_r17\n");
ntn_ta->N_UE_TA_adj = 0;
ntn_ta->N_UE_TA_drift = 0;
ntn_ta->N_UE_TA_drift_variant = 0;
}
} else { // Need R - Release if not present
ntn_ta->N_UE_TA_adj = 0;
ntn_ta->N_UE_TA_drift = 0;
ntn_ta->N_UE_TA_drift_variant = 0;
}
// handle cellSpecificKoffset_r17
@@ -356,7 +367,8 @@ static void configure_ntn_ta(module_id_t module_id,
ntn_ta->ntn_params_changed = true;
LOG_D(NR_MAC,
"SIB19 Rxd. Epoch SFN: %d, Epoch Subframe: %d, k_offset: %ldms, N_Common_Ta: %fms, drift: %fµs/s, variant %fµs/s², N_UE_TA: %fms, drift: %fµs/s\n",
"SIB19 Rxd. Epoch SFN: %d, Epoch Subframe: %d, k_offset: %ldms, N_Common_Ta: %fms, drift: %fµs/s, variant %fµs/s², "
"N_UE_TA: %fms, drift: %fµs/s, variant %fµs/s²\n",
ntn_ta->epoch_sfn,
ntn_ta->epoch_subframe,
ntn_ta->cell_specific_k_offset,
@@ -364,7 +376,8 @@ static void configure_ntn_ta(module_id_t module_id,
ntn_ta->N_common_ta_drift,
ntn_ta->N_common_ta_drift_variant,
ntn_ta->N_UE_TA_adj,
ntn_ta->N_UE_TA_drift);
ntn_ta->N_UE_TA_drift,
ntn_ta->N_UE_TA_drift_variant);
}
static void config_common_ue(NR_UE_MAC_INST_t *mac, NR_ServingCellConfigCommon_t *scc, int cc_idP)
openair2/LAYER2/NR_MAC_UE/mac_defs.h
+7
View File
@@ -541,6 +541,8 @@ typedef struct ntn_timing_advance_components {
double N_UE_TA_adj;
// drift rate of N_UE_TA in µs/s
double N_UE_TA_drift;
// change rate of N_UE_TA drift in µs/s²
double N_UE_TA_drift_variant;
// cell scheduling offset expressed in terms of 15kHz SCS
long cell_specific_k_offset;
@@ -674,5 +676,10 @@ static inline double get_total_TA_drift(const ntn_timing_advance_componets_t *nt
return ntn_ta->N_common_ta_drift + ntn_ta->N_UE_TA_drift;
}
static inline double get_total_TA_drift_variant(const ntn_timing_advance_componets_t *ntn_ta)
{
return ntn_ta->N_common_ta_drift_variant + ntn_ta->N_UE_TA_drift_variant;
}
/*@}*/
#endif /*__LAYER2_MAC_DEFS_H__ */
openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
+1 -1
View File
@@ -2854,7 +2854,7 @@ static void schedule_ntn_config_command(fapi_nr_dl_config_request_t *dl_config,
ntn_config_command_pdu->cell_specific_k_offset = mac->ntn_ta.cell_specific_k_offset;
ntn_config_command_pdu->ntn_total_time_advance_ms = get_total_TA_ms(&mac->ntn_ta);
ntn_config_command_pdu->ntn_total_time_advance_drift = get_total_TA_drift(&mac->ntn_ta);
ntn_config_command_pdu->ntn_total_time_advance_drift_variant = mac->ntn_ta.N_common_ta_drift_variant;
ntn_config_command_pdu->ntn_total_time_advance_drift_variant = get_total_TA_drift_variant(&mac->ntn_ta);
dl_config->dl_config_list[dl_config->number_pdus].pdu_type = FAPI_NR_DL_NTN_CONFIG_PARAMS;
dl_config->number_pdus += 1;