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NR UE: set time sync PI controller integral weight to 0.0 by default

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Experiments did show that the time sync is less stable in terrestrial mode if the integral part of the PI controller is used.
So set it to 0.0 by default. For NTN LEO use case we can still use it by providing the command line parameter --time-sync-I 0.2 .
fixes #846
This commit is contained in:
Thomas Schlichter
2024-09-27 17:06:42 +02:00
parent 64380eaca2
commit 791cc4f648
3 changed files with 7 additions and 3 deletions
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executables/nr-ue.c
+5 -1
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@@ -883,7 +883,11 @@ void *UE_thread(void *arg)
stream_status = STREAM_STATUS_SYNCING;
syncInFrame(UE, &sync_timestamp, intialSyncOffset);
openair0_write_reorder_clear_context(&UE->rfdevice);
UE->max_pos_acc = get_nrUE_params()->ntn_ta_commondrift * 1e-6 * fp->samples_per_frame / get_nrUE_params()->time_sync_I; // ntn_ta_commondrift is in µs/s, max_pos_acc * time_sync_I is in samples/frame
if (get_nrUE_params()->time_sync_I)
// ntn_ta_commondrift is in µs/s, max_pos_acc * time_sync_I is in samples/frame
UE->max_pos_acc = get_nrUE_params()->ntn_ta_commondrift * 1e-6 * fp->samples_per_frame / get_nrUE_params()->time_sync_I;
else
UE->max_pos_acc = 0;
shiftForNextFrame = -(UE->init_sync_frame + trashed_frames + 2) * UE->max_pos_acc * get_nrUE_params()->time_sync_I; // compensate for the time drift that happened during initial sync
LOG_D(PHY, "max_pos_acc = %d, shiftForNextFrame = %d\n", UE->max_pos_acc, shiftForNextFrame);
// TODO: remove this autonomous TA and use up-to-date values of ta-Common, ta-CommonDrift and ta-CommonDriftVariant from received SIB19 instead
executables/nr-uesoftmodem.h
+1 -1
View File
@@ -65,7 +65,7 @@
{"SLC", CONFIG_HLP_SLF, 0, .u64ptr=&(sidelink_frequency[0][0]), .defuintval=2600000000,TYPE_UINT64,0}, \
{"num-ues", NULL, 0, .iptr=&(NB_UE_INST), .defuintval=1, TYPE_INT, 0}, \
{"time-sync-P", CONFIG_HLP_TIME_SYNC_P, 0, .dblptr=&(nrUE_params.time_sync_P), .defdblval=0.5, TYPE_DOUBLE, 0}, \
{"time-sync-I", CONFIG_HLP_TIME_SYNC_I, 0, .dblptr=&(nrUE_params.time_sync_I), .defdblval=0.2, TYPE_DOUBLE, 0}, \
{"time-sync-I", CONFIG_HLP_TIME_SYNC_I, 0, .dblptr=&(nrUE_params.time_sync_I), .defdblval=0.0, TYPE_DOUBLE, 0}, \
{"ntn-koffset", CONFIG_HLP_NTN_KOFFSET, 0, .uptr=&(nrUE_params.ntn_koffset), .defuintval=0, TYPE_UINT, 0}, \
{"ntn-ta-common", CONFIG_HLP_NTN_TA_COMMON, 0, .dblptr=&(nrUE_params.ntn_ta_common), .defdblval=0.0, TYPE_DOUBLE, 0}, \
{"ntn-ta-commondrift", CONFIG_HLP_NTN_TA_COMMONDRIFT, 0, .dblptr=&(nrUE_params.ntn_ta_commondrift), .defdblval=0.0, TYPE_DOUBLE, 0}, \