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Adjust sync based on PSS

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This commit is contained in:
luis_pereira87
2021-12-24 10:26:52 +00:00
parent f508d8c80d
commit 22754562cf
6 changed files with 101 additions and 3 deletions
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executables/nr-ue.c
+3 -1
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@@ -642,7 +642,9 @@ void *UE_thread(void *arg) {
readBlockSize=get_readBlockSize(slot_nr, &UE->frame_parms);
writeBlockSize=UE->frame_parms.get_samples_per_slot((slot_nr + DURATION_RX_TO_TX - NR_RX_NB_TH) % nb_slot_frame, &UE->frame_parms);
} else {
UE->rx_offset_diff = computeSamplesShift(UE);
//UE->rx_offset_diff = computeSamplesShift(UE);
readBlockSize=get_readBlockSize(slot_nr, &UE->frame_parms) -
UE->rx_offset_diff;
writeBlockSize=UE->frame_parms.get_samples_per_slot((slot_nr + DURATION_RX_TO_TX - NR_RX_NB_TH) % nb_slot_frame, &UE->frame_parms)- UE->rx_offset_diff;
openair1/PHY/NR_REFSIG/pss_nr.h
+2
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@@ -141,6 +141,8 @@ int pss_search_time_nr(int **rxdata, ///rx data in time domain
int *eNB_id,
int *f_off);
int nr_adjust_pss_synch(PHY_VARS_NR_UE *ue, int *f_off);
#endif
#undef EXTERN
openair1/PHY/NR_UE_TRANSPORT/pss_nr.c
+85
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@@ -34,6 +34,7 @@
#include <assert.h>
#include <errno.h>
#include <math.h>
#include <nr-uesoftmodem.h>
#include "PHY/defs_nr_UE.h"
@@ -975,3 +976,87 @@ int pss_search_time_nr(int **rxdata, ///rx data in time domain
return(peak_position);
}
int nr_adjust_pss_synch(PHY_VARS_NR_UE *ue, int *f_off) {
int **rxdata = ue->common_vars.rxdata;
NR_DL_FRAME_PARMS *frame_parms = &ue->frame_parms;
uint8_t Nid2 = GET_NID2(frame_parms->Nid_cell);
int maxval=0;
for (int i=0;i<2*(frame_parms->ofdm_symbol_size);i++) {
maxval = max(maxval,primary_synchro_time_nr[Nid2][i]);
maxval = max(maxval,-primary_synchro_time_nr[Nid2][i]);
}
int shift = log2_approx(maxval);
/* Search pss in the received buffer each 4 samples which ensures a memory alignment on 128 bits (32 bits x 4 ) */
/* This is required by SIMD (single instruction Multiple Data) Extensions of Intel processors. */
/* Correlation computation is based on a dot product which is realized thank to SIMS extensions */
int64_t peak_value = 0;
int peak_position = 0;
int64_t result = 0;
int64_t avg=0;
int start = 2*(frame_parms->ofdm_symbol_size + frame_parms->nb_prefix_samples) + frame_parms->nb_prefix_samples0 - 200;
int length = 2*frame_parms->ofdm_symbol_size + 200;
memset(pss_corr_ue[Nid2],0,(start+length)*sizeof(int64_t));
for (int n=start; n < start+length; n+=4) { //
for (int ar=0; ar<frame_parms->nb_antennas_rx; ar++) {
result = dot_product64((short*)primary_synchro_time_nr[Nid2],
(short*) &(rxdata[ar][n]),
frame_parms->ofdm_symbol_size,
shift);
pss_corr_ue[Nid2][n] += abs64(result);
}
avg+=pss_corr_ue[Nid2][n];
if (pss_corr_ue[Nid2][n] > peak_value) {
peak_value = pss_corr_ue[Nid2][n];
peak_position = n;
}
}
avg/=(length/4);
if (peak_value < 5*avg) {
return 0;
}
int peak_position_diff = peak_position - ( ((frame_parms->ofdm_symbol_size + frame_parms->nb_prefix_samples)<<1) + frame_parms->nb_prefix_samples0);
// Fractional frequency offset computation according to Cross-correlation Synchronization Algorithm Using PSS
// Shoujun Huang, Yongtao Su, Ying He and Shan Tang, "Joint time and frequency offset estimation in LTE downlink,"
// 7th International Conference on Communications and Networking in China, 2012.
// Computing cross-correlation at peak on half the symbol size for first half of data
int64_t result1 = dot_product64((short*)primary_synchro_time_nr[Nid2],
(short*) &(rxdata[0][peak_position]),
frame_parms->ofdm_symbol_size>>1,
shift);
// Computing cross-correlation at peak on half the symbol size for data shifted by half symbol size
// as it is real and complex it is necessary to shift by a value equal to symbol size to obtain such shift
int64_t result2 = dot_product64((short*)primary_synchro_time_nr[Nid2]+(frame_parms->ofdm_symbol_size),
(short*) &(rxdata[0][peak_position])+frame_parms->ofdm_symbol_size,
frame_parms->ofdm_symbol_size>>1,
shift);
int64_t re1 = ((int*) &result1)[0];
int64_t re2 = ((int*) &result2)[0];
int64_t im1 = ((int*) &result1)[1];
int64_t im2 = ((int*) &result2)[1];
// Estimation of fractional frequency offset: angle[(result1)'*(result2)]/pi
double ffo_est = atan2(re1*im2-re2*im1,re1*re2+im1*im2)/M_PI;
// Computing absolute value of frequency offset
*f_off = ffo_est*frame_parms->subcarrier_spacing;
/*nr_rf_card_config_freq(&openair0_cfg[ue->rf_map.card], openair0_cfg->tx_freq[0], openair0_cfg->rx_freq[0], ue->common_vars.freq_offset);
if (ue->mode != loop_through_memory) {
ue->rfdevice.trx_set_freq_func(&ue->rfdevice,&openair0_cfg[0],0);
}*/
LOG_I(NR_PHY,"nr_adjust_pss_synch: peak_position %d, peak_position_diff %d, peak_value %d dB, avg %d dB, ffo %lf\n",
peak_position, peak_position_diff, dB_fixed64(peak_value),dB_fixed64(avg),ffo_est);
return peak_position_diff;
}
openair1/SCHED_NR_UE/phy_procedures_nr_ue.c
+9 -2
View File
@@ -39,6 +39,7 @@
#include "PHY/phy_extern_nr_ue.h"
#include "PHY/MODULATION/modulation_UE.h"
#include "PHY/NR_REFSIG/refsig_defs_ue.h"
#include "PHY/NR_REFSIG/pss_nr.h"
#include "PHY/NR_UE_TRANSPORT/nr_transport_ue.h"
#include "PHY/NR_UE_TRANSPORT/nr_transport_proto_ue.h"
#include "SCHED_NR_UE/defs.h"
@@ -1647,10 +1648,12 @@ int phy_procedures_nrUE_RX(PHY_VARS_NR_UE *ue,
if ((ue->decode_MIB == 1) && slot_pbch) {
int peak_position_diff = nr_adjust_pss_synch(ue, (int *)&ue->common_vars.freq_offset);
LOG_D(PHY," ------ Decode MIB: frame.slot %d.%d ------ \n", frame_rx%1024, nr_slot_rx);
nr_ue_pbch_procedures(gNB_id, ue, proc, 0);
if (ue->no_timing_correction==0) {
/* if (ue->no_timing_correction==0) {
LOG_D(PHY,"start adjust sync slot = %d no timing %d\n", nr_slot_rx, ue->no_timing_correction);
nr_adjust_synch_ue(fp,
ue,
@@ -1659,7 +1662,11 @@ int phy_procedures_nrUE_RX(PHY_VARS_NR_UE *ue,
nr_slot_rx,
0,
16384);
}
}*/
//ue->rx_offset = peak_position_diff;
ue->rx_offset_diff = -peak_position_diff;
LOG_D(PHY, "Doing N0 measurements in %s\n", __FUNCTION__);
nr_ue_rrc_measurements(ue, proc, nr_slot_rx);
targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band78.fr1.106PRB.2x2.usrpn300.conf
+1
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@@ -35,6 +35,7 @@ gNBs =
ssb_SubcarrierOffset = 0;
pdsch_AntennaPorts = 1;
pusch_AntennaPorts = 2;
min_rxtxtime_pdsch = 6;
ul_prbblacklist = "51,52,53,54"
pdcch_ConfigSIB1 = (
targets/PROJECTS/GENERIC-NR-5GC/CONF/gnb.sa.band78.fr1.106PRB.usrpb210.conf
+1
View File
@@ -35,6 +35,7 @@ gNBs =
ssb_SubcarrierOffset = 0;
pdsch_AntennaPorts = 1;
pusch_AntennaPorts = 1;
min_rxtxtime_pdsch = 6;
sib1_tda = 0;
pdcch_ConfigSIB1 = (