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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/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c
+28 -31
View File
@@ -555,21 +555,24 @@ int nr_prs_channel_estimation(uint8_t gNB_id,
return(0);
}
c32_t nr_pbch_dmrs_correlation(const PHY_VARS_NR_UE *ue,
c32_t nr_pbch_dmrs_correlation(const NR_DL_FRAME_PARMS *fp,
const UE_nr_rxtx_proc_t *proc,
const int symbol,
const int dmrss,
const int Nid_cell,
const int ssb_start_subcarrier,
const uint32_t nr_gold_pbch[NR_PBCH_DMRS_LENGTH_DWORD],
const c16_t rxdataF[][ue->frame_parms.samples_per_slot_wCP])
const c16_t rxdataF[][fp->samples_per_slot_wCP])
{
AssertFatal(dmrss >= 0 && dmrss < 3, "symbol %d is illegal for PBCH DM-RS \n", dmrss);
unsigned int ssb_offset = ue->frame_parms.first_carrier_offset + ue->frame_parms.ssb_start_subcarrier;
if (ssb_offset>= ue->frame_parms.ofdm_symbol_size) ssb_offset-=ue->frame_parms.ofdm_symbol_size;
unsigned int ssb_offset = fp->first_carrier_offset + ssb_start_subcarrier;
if (ssb_offset >= fp->ofdm_symbol_size)
ssb_offset -= fp->ofdm_symbol_size;
int symbol_offset = ue->frame_parms.ofdm_symbol_size * symbol;
int symbol_offset = fp->ofdm_symbol_size * symbol;
unsigned int k = ue->frame_parms.Nid_cell % 4;
unsigned int k = Nid_cell % 4;
DEBUG_PBCH("PBCH DMRS Correlation : gNB_id %d , OFDM size %d, Ncp=%d, k=%u symbol %d\n",
proc->gNB_id,
@@ -583,8 +586,7 @@ c32_t nr_pbch_dmrs_correlation(const PHY_VARS_NR_UE *ue,
c16_t pilot[200] __attribute__((aligned(16)));
nr_pbch_dmrs_rx(dmrss, (uint32_t *)nr_gold_pbch, pilot, false);
c32_t computed_val = {0};
for (int aarx=0; aarx<ue->frame_parms.nb_antennas_rx; aarx++) {
for (int aarx = 0; aarx < fp->nb_antennas_rx; aarx++) {
int re_offset = ssb_offset;
c16_t *pil = pilot;
const c16_t *rxF = &rxdataF[aarx][symbol_offset + k];
@@ -599,49 +601,50 @@ c32_t nr_pbch_dmrs_correlation(const PHY_VARS_NR_UE *ue,
DEBUG_PBCH("pilot 0 : rxF - > (%d,%d) pil -> (%d,%d) \n", rxF[re_offset].r, rxF[re_offset].i, pil->r, pil->i);
pil++;
re_offset = (re_offset+4) % ue->frame_parms.ofdm_symbol_size;
re_offset = (re_offset + 4) % fp->ofdm_symbol_size;
computed_val = c32x16maddShift(*pil, rxF[re_offset], computed_val, 15);
DEBUG_PBCH("pilot 1 : rxF - > (%d,%d) pil -> (%d,%d) \n", rxF[re_offset].r, rxF[re_offset].i, pil->r, pil->i);
pil++;
re_offset = (re_offset+4) % ue->frame_parms.ofdm_symbol_size;
re_offset = (re_offset + 4) % fp->ofdm_symbol_size;
computed_val = c32x16maddShift(*pil, rxF[re_offset], computed_val, 15);
DEBUG_PBCH("pilot 2 : rxF - > (%d,%d), pil -> (%d,%d) \n", rxF[re_offset].r, rxF[re_offset].i, pil->r, pil->i);
pil++;
re_offset = (re_offset + 4) % ue->frame_parms.ofdm_symbol_size;
re_offset = (re_offset + 4) % fp->ofdm_symbol_size;
for (int pilot_cnt = 3; pilot_cnt < (3 * 20); pilot_cnt += 3) {
// in 2nd symbol, skip middle REs (48 with DMRS, 144 for SSS, and another 48 with DMRS)
if (dmrss == 1 && pilot_cnt == 12) {
pilot_cnt=48;
re_offset = (re_offset + 144) % ue->frame_parms.ofdm_symbol_size;
re_offset = (re_offset + 144) % fp->ofdm_symbol_size;
}
computed_val = c32x16maddShift(*pil, rxF[re_offset], computed_val, 15);
DEBUG_PBCH("pilot %u : rxF= (%d,%d) pil= (%d,%d) \n", pilot_cnt, rxF[re_offset].r, rxF[re_offset].i, pil->r, pil->i);
pil++;
re_offset = (re_offset+4) % ue->frame_parms.ofdm_symbol_size;
re_offset = (re_offset + 4) % fp->ofdm_symbol_size;
computed_val = c32x16maddShift(*pil, rxF[re_offset], computed_val, 15);
DEBUG_PBCH("pilot %u : rxF= (%d,%d) pil= (%d,%d) \n", pilot_cnt + 1, rxF[re_offset].r, rxF[re_offset].i, pil->r, pil->i);
pil++;
re_offset = (re_offset+4) % ue->frame_parms.ofdm_symbol_size;
re_offset = (re_offset + 4) % fp->ofdm_symbol_size;
computed_val = c32x16maddShift(*pil, rxF[re_offset], computed_val, 15);
DEBUG_PBCH("pilot %u : rxF= (%d,%d) pil= (%d,%d) \n", pilot_cnt + 2, rxF[re_offset].r, rxF[re_offset].i, pil->r, pil->i);
pil++;
re_offset = (re_offset + 4) % ue->frame_parms.ofdm_symbol_size;
re_offset = (re_offset + 4) % fp->ofdm_symbol_size;
}
}
return computed_val;
}
int nr_pbch_channel_estimation(PHY_VARS_NR_UE *ue,
NR_DL_FRAME_PARMS *fp,
int nr_pbch_channel_estimation(const NR_DL_FRAME_PARMS *fp,
const sl_nr_ue_phy_params_t *sl_phy_params,
const uint32_t nr_gold_pbch[2][64][NR_PBCH_DMRS_LENGTH_DWORD],
int estimateSz,
struct complex16 dl_ch_estimates[][estimateSz],
struct complex16 dl_ch_estimates_time[][fp->ofdm_symbol_size],
@@ -650,7 +653,8 @@ int nr_pbch_channel_estimation(PHY_VARS_NR_UE *ue,
int dmrss,
uint8_t ssb_index,
uint8_t n_hf,
c16_t rxdataF[][fp->samples_per_slot_wCP],
int ssb_start_subcarrier,
const c16_t rxdataF[][fp->samples_per_slot_wCP],
bool sidelink,
uint16_t Nid)
{
@@ -659,13 +663,11 @@ int nr_pbch_channel_estimation(PHY_VARS_NR_UE *ue,
//int slot_pbch;
uint8_t nushift = 0, lastsymbol = 0, num_rbs = 0;
uint32_t *gold_seq = NULL;
const uint32_t *gold_seq = NULL;
if (sidelink) {
AssertFatal(dmrss == 0 || (dmrss >= 5 && dmrss <= 12), "symbol %d is illegal for PSBCH DM-RS \n", dmrss);
sl_nr_ue_phy_params_t *sl_phy_params = &ue->SL_UE_PHY_PARAMS;
LOG_D(PHY, "PSBCH Channel Estimation SLSSID:%d\n", Nid);
gold_seq = sl_phy_params->init_params.psbch_dmrs_gold_sequences[Nid];
@@ -673,16 +675,16 @@ int nr_pbch_channel_estimation(PHY_VARS_NR_UE *ue,
num_rbs = SL_NR_NUM_PSBCH_RBS_IN_ONE_SYMBOL;
} else {
nushift = fp->Nid_cell % 4;
nushift = Nid % 4;
AssertFatal(dmrss >= 0 && dmrss < 3, "symbol %d is illegal for PBCH DM-RS \n", dmrss);
gold_seq = ue->nr_gold_pbch[n_hf][ssb_index];
gold_seq = nr_gold_pbch[n_hf][ssb_index];
lastsymbol = 2;
num_rbs = 20;
}
unsigned int ssb_offset = fp->first_carrier_offset + fp->ssb_start_subcarrier;
unsigned int ssb_offset = fp->first_carrier_offset + ssb_start_subcarrier;
if (ssb_offset >= fp->ofdm_symbol_size)
ssb_offset -= fp->ofdm_symbol_size;
@@ -739,7 +741,7 @@ int nr_pbch_channel_estimation(PHY_VARS_NR_UE *ue,
for (int aarx = 0; aarx < fp->nb_antennas_rx; aarx++) {
int re_offset = ssb_offset;
c16_t *pil = pilot;
c16_t *rxF = &rxdataF[aarx][symbol_offset + k];
const c16_t *rxF = &rxdataF[aarx][symbol_offset + k];
c16_t *dl_ch = &dl_ch_estimates[aarx][ch_offset];
memset(dl_ch, 0, sizeof(c16_t) * fp->ofdm_symbol_size);
@@ -824,15 +826,10 @@ int nr_pbch_channel_estimation(PHY_VARS_NR_UE *ue,
{
// do ifft of channel estimate
LOG_D(PHY,"Channel Impulse Computation Slot %d Symbol %d ch_offset %d\n", Ns, symbol, ch_offset);
freq2time(ue->frame_parms.ofdm_symbol_size,
(int16_t *)&dl_ch_estimates[aarx][ch_offset],
(int16_t *)&dl_ch_estimates_time[aarx]);
freq2time(fp->ofdm_symbol_size, (int16_t *)&dl_ch_estimates[aarx][ch_offset], (int16_t *)&dl_ch_estimates_time[aarx]);
}
}
if (!sidelink && dmrss == lastsymbol)
UEscopeCopy(ue, pbchDlChEstimateTime, (void *)dl_ch_estimates_time, sizeof(c16_t), fp->nb_antennas_rx, fp->ofdm_symbol_size, 0);
return(0);
}
openair1/PHY/NR_UE_ESTIMATION/nr_estimation.h
+9 -5
View File
@@ -57,15 +57,18 @@ void nr_pdcch_channel_estimation(PHY_VARS_NR_UE *ue,
c16_t pdcch_dl_ch_estimates[][pdcch_est_size],
c16_t rxdataF[][ue->frame_parms.samples_per_slot_wCP]);
c32_t nr_pbch_dmrs_correlation(const PHY_VARS_NR_UE *ue,
c32_t nr_pbch_dmrs_correlation(const NR_DL_FRAME_PARMS *fp,
const UE_nr_rxtx_proc_t *proc,
const int symbol,
const int dmrss,
const int Nid_cell,
const int ssb_start_subcarrier,
const uint32_t nr_gold_pbch[NR_PBCH_DMRS_LENGTH_DWORD],
const c16_t rxdataF[][ue->frame_parms.samples_per_slot_wCP]);
const c16_t rxdataF[][fp->samples_per_slot_wCP]);
int nr_pbch_channel_estimation(PHY_VARS_NR_UE *ue,
NR_DL_FRAME_PARMS *fp,
int nr_pbch_channel_estimation(const NR_DL_FRAME_PARMS *fp,
const sl_nr_ue_phy_params_t *sl_phy_params,
const uint32_t nr_gold_pbch[2][64][NR_PBCH_DMRS_LENGTH_DWORD],
int estimateSz,
struct complex16 dl_ch_estimates[][estimateSz],
struct complex16 dl_ch_estimates_time[][fp->ofdm_symbol_size],
@@ -74,7 +77,8 @@ int nr_pbch_channel_estimation(PHY_VARS_NR_UE *ue,
int dmrss,
uint8_t ssb_index,
uint8_t n_hf,
c16_t rxdataF[][fp->samples_per_slot_wCP],
int ssb_start_subcarrier,
const c16_t rxdataF[][fp->samples_per_slot_wCP],
bool sidelink,
uint16_t Nid);