From 791cc4f64803d22eb0352b376906c9724078485e Mon Sep 17 00:00:00 2001 From: Thomas Schlichter Date: Fri, 27 Sep 2024 12:19:25 +0200 Subject: [PATCH] NR UE: set time sync PI controller integral weight to 0.0 by default 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 --- doc/RUNMODEM.md | 2 +- executables/nr-ue.c | 6 +++++- executables/nr-uesoftmodem.h | 2 +- 3 files changed, 7 insertions(+), 3 deletions(-) diff --git a/doc/RUNMODEM.md b/doc/RUNMODEM.md index 1bc6268199..fef128e2f7 100644 --- a/doc/RUNMODEM.md +++ b/doc/RUNMODEM.md @@ -298,7 +298,7 @@ Also, to perform an autonomous TA update based on the DL drift, the boolean para So an example NR UE command for FDD, 5MHz BW, 15 kHz SCS, transparent LEO satellite 5G NR NTN is this: ``` cd cmake_targets -sudo ./ran_build/build/nr-uesoftmodem --band 66 -C 2152680000 --CO -400000000 -r 25 --numerology 0 --ssb 48 --sa --rfsim --rfsimulator.prop_delay 20 --rfsimulator.options chanmod -O ../targets/PROJECTS/GENERIC-NR-5GC/CONF/channelmod_rfsimu_LEO_satellite.conf --ntn-koffset 40 --ntn-ta-common 37.74 --ntn-ta-commondrift -50 --autonomous-ta +sudo ./ran_build/build/nr-uesoftmodem --band 66 -C 2152680000 --CO -400000000 -r 25 --numerology 0 --ssb 48 --sa --rfsim --rfsimulator.prop_delay 20 --rfsimulator.options chanmod -O ../targets/PROJECTS/GENERIC-NR-5GC/CONF/channelmod_rfsimu_LEO_satellite.conf --time-sync-I 0.2 --ntn-koffset 40 --ntn-ta-common 37.74 --ntn-ta-commondrift -50 --autonomous-ta ``` # Specific OAI modes diff --git a/executables/nr-ue.c b/executables/nr-ue.c index a742ea2e9d..d26547b14b 100644 --- a/executables/nr-ue.c +++ b/executables/nr-ue.c @@ -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 diff --git a/executables/nr-uesoftmodem.h b/executables/nr-uesoftmodem.h index 797b5d8f49..65327cc3b2 100644 --- a/executables/nr-uesoftmodem.h +++ b/executables/nr-uesoftmodem.h @@ -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}, \