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NR UE scan for SSB within current bandwidth

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Till this commit, the UE gets the position of SSB in frequency from
command line and does the syncronization by locating the SSB in time. It
does this by generating a PSS time signal during initialization with the
SSB offset given via command line. Then PSS detection is done by
correlation.

In this commit, the UE computes a list of GSCN in the current NR band
that falls within the current bandwidth for the set center frequency.
For each GSCN in the list, the UE starts a thread and performs the
following:
1. Generate PSS time signal with SSB offset for current GSCN.
2. Detect PSS, SSS and decode PBCH (this step remains the same).
After all threads finishes, the results are collected.

For now, only the first detected PBCH is used to proceed further. So
this PBCH is indicated to MAC and UE exits initial sync.

Future work: The cell search can be standalone feature where the UE
could scan for SSB in the entire NR band. This would require changing
radio's frequency on the fly as the UE's bandwidth would not cover an
entire NR band. The cell detection can futher be imporved by looking
for SIB1 for each decoded PBCH.
This commit is contained in:
Sakthivel Velumani
2024-05-30 10:20:45 -04:00
parent 082007834c
commit 043da0c440
28 changed files with 845 additions and 570 deletions
Download Patch File Download Diff File Expand all files Collapse all files
openair1/SIMULATION/NR_PHY/dlsim.c
+1 -1
View File
@@ -823,7 +823,7 @@ int main(int argc, char **argv)
init_nr_ue_transport(UE);
nr_gold_pbch(UE);
nr_gold_pbch(UE->nr_gold_pbch, frame_parms->Nid_cell, frame_parms->Lmax);
// compute the scramblingID_pdcch and the gold pdcch
UE->scramblingID_pdcch = frame_parms->Nid_cell;
openair1/SIMULATION/NR_PHY/pbchsim.c
+19 -10
View File
@@ -199,6 +199,7 @@ int main(int argc, char **argv)
uint16_t Nid_cell=0;
uint64_t SSB_positions=0x01;
int ssb_subcarrier_offset = 0;
int ssb_scan_threads = 0;
channel_desc_t *gNB2UE;
get_softmodem_params()->sa = 1;
@@ -493,8 +494,9 @@ int main(int argc, char **argv)
set_tdd_config_nr(&gNB->gNB_config, mu, 7, 6, 2, 4);
phy_init_nr_gNB(gNB);
frame_parms->ssb_start_subcarrier = 12 * gNB->gNB_config.ssb_table.ssb_offset_point_a.value + ssb_subcarrier_offset;
initFloatingCoresTpool(ssb_scan_threads, &nrUE_params.Tpool, false, "UE-tpool");
uint8_t n_hf = 0;
int n_hf = 0;
int cyclic_prefix_type = NFAPI_CP_NORMAL;
double fs=0, eps;
@@ -608,7 +610,7 @@ int main(int argc, char **argv)
exit(-1);
}
nr_gold_pbch(UE);
nr_gold_pbch(UE->nr_gold_pbch, Nid_cell, frame_parms->Lmax);
processingData_L1tx_t msgDataTx;
// generate signal
@@ -759,13 +761,16 @@ int main(int argc, char **argv)
}
if (n_trials==1) {
LOG_M("rxsig0.m","rxs0", UE->common_vars.rxdata[0],frame_parms->samples_per_frame,1,1);
if (gNB->frame_parms.nb_antennas_tx>1)
LOG_M("rxsig1.m","rxs1", UE->common_vars.rxdata[1],frame_parms->samples_per_frame,1,1);
LOG_M("rxsig0.m", "rxs0", UE->common_vars.rxdata[0], frame_parms->samples_per_frame, 1, 1);
if (gNB->frame_parms.nb_antennas_tx > 1)
LOG_M("rxsig1.m", "rxs1", UE->common_vars.rxdata[1], frame_parms->samples_per_frame, 1, 1);
}
if (UE->is_synchronized == 0) {
UE_nr_rxtx_proc_t proc={0};
nr_initial_sync_t ret = nr_initial_sync(&proc, UE, 1, 0);
UE_nr_rxtx_proc_t proc = {0};
nr_gscn_info_t gscnInfo[MAX_GSCN_BAND] = {0};
const int numGscn = 1;
gscnInfo[0].ssbFirstSC = frame_parms->ssb_start_subcarrier;
nr_initial_sync_t ret = nr_initial_sync(&proc, UE, 1, 0, gscnInfo, numGscn);
printf("nr_initial_sync1 returns %s\n", ret.cell_detected ? "cell detected" : "cell not detected");
if (!ret.cell_detected)
n_errors++;
@@ -788,8 +793,9 @@ int main(int argc, char **argv)
for (int i = UE->symbol_offset + 1; i < UE->symbol_offset + 4; i++) {
nr_slot_fep(UE, frame_parms, &proc, i % frame_parms->symbols_per_slot, rxdataF, link_type_dl);
nr_pbch_channel_estimation(UE,
&UE->frame_parms,
nr_pbch_channel_estimation(&UE->frame_parms,
&UE->SL_UE_PHY_PARAMS,
UE->nr_gold_pbch,
estimateSz,
dl_ch_estimates,
dl_ch_estimates_time,
@@ -798,12 +804,15 @@ int main(int argc, char **argv)
i - (UE->symbol_offset + 1),
ssb_index % 8,
n_hf,
frame_parms->ssb_start_subcarrier,
rxdataF,
false,
frame_parms->Nid_cell);
}
fapiPbch_t result;
ret = nr_rx_pbch(UE, &proc, estimateSz, dl_ch_estimates, frame_parms, ssb_index % 8, &result, rxdataF);
int ret_ssb_idx;
int ret_symbol_offset;
ret = nr_rx_pbch(UE, &proc, true, estimateSz, dl_ch_estimates, frame_parms, ssb_index % 8, frame_parms->ssb_start_subcarrier, Nid_cell, &result, &n_hf, &ret_ssb_idx, &ret_symbol_offset, rxdataF);
if (ret == 0) {
// UE->rx_ind.rx_indication_body->mib_pdu.ssb_index; //not yet detected automatically