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srsRAN_4G
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Calculate ssb frequency from freqency point a.

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master
Fabian Eckermann 3 years ago committed by Andre Puschmann
parent ca19b466bb
commit 95abfbfec8
4 changed files with 58 additions and 40 deletions
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12
lib/include/srsran/common/band_helper.h
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@ -114,6 +114,18 @@ public:
*/
uint32_t get_abs_freq_point_a_arfcn(uint32_t nof_prb, uint32_t arfcn);
/**
* @brief Compute the absolute frequency of the SSB for a DL ARFCN and a band. sThis selects an SSB center frequency
* following the band SS/PBCH frequency raster provided by 38.104 table 5.4.3.1-1 as close as possible to PointA
* without letting any SS/PBCH subcarrier below PointA
*
* @param band nr frequency band.
* @param scs ssb subcarrier spacing.
* @param freq_point_a_arfcn frequency point a in arfcn notation.
* @return absolute frequency of the SSB in arfcn notation.
*/
uint32_t get_abs_freq_ssb_arfcn(uint16_t band, srsran_subcarrier_spacing_t scs, uint32_t freq_point_a_arfcn);
class sync_raster_t
{
protected:

23
lib/src/common/band_helper.cc
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@ -133,6 +133,29 @@ double srsran_band_helper::get_abs_freq_point_a_from_center_freq(uint32_t nof_pr
SRSRAN_NRE);
}
uint32_t
srsran_band_helper::get_abs_freq_ssb_arfcn(uint16_t band, srsran_subcarrier_spacing_t scs, uint32_t freq_point_a_arfcn)
{
double ssb_bw_hz = SRSRAN_SSB_BW_SUBC * SRSRAN_SUBC_SPACING_NR(scs);
sync_raster_t sync_raster = get_sync_raster(band, scs);
if (!sync_raster.valid()) {
return 0;
}
double abs_freq_ssb_hz = sync_raster.get_frequency();
while (abs_freq_ssb_hz < (nr_arfcn_to_freq(freq_point_a_arfcn) + ssb_bw_hz / 2)) {
sync_raster.next();
if (sync_raster.end()) {
return 0;
}
abs_freq_ssb_hz = sync_raster.get_frequency();
}
return freq_to_nr_arfcn(abs_freq_ssb_hz);
}
srsran_ssb_patern_t srsran_band_helper::get_ssb_pattern(uint16_t band, srsran_subcarrier_spacing_t scs) const
{
// Look for the given band and SCS

15
srsenb/src/enb_cfg_parser.cc
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@ -1525,6 +1525,21 @@ int set_derived_args_nr(all_args_t* args_, rrc_nr_cfg_t* rrc_cfg_, phy_cfg_t* ph
cfg.phy_cell.pdcch.ra_search_space = cfg.phy_cell.pdcch.search_space[1];
cfg.phy_cell.pdcch.ra_search_space.type = srsran_search_space_type_common_1;
// point a
cfg.phy_cell.carrier.dl_absolute_frequency_point_a =
band_helper.get_abs_freq_point_a_arfcn(cfg.phy_cell.carrier.nof_prb, cfg.dl_arfcn);
cfg.phy_cell.carrier.ul_absolute_frequency_point_a =
band_helper.get_abs_freq_point_a_arfcn(cfg.phy_cell.carrier.nof_prb, cfg.ul_arfcn);
// ssb freq
if (band_helper.get_ssb_pattern(cfg.band, srsran_subcarrier_spacing_15kHz) != SRSRAN_SSB_PATTERN_INVALID) {
cfg.phy_cell.carrier.absolute_frequency_ssb = band_helper.get_abs_freq_ssb_arfcn(
cfg.band, srsran_subcarrier_spacing_15kHz, cfg.phy_cell.carrier.dl_absolute_frequency_point_a);
} else {
cfg.phy_cell.carrier.absolute_frequency_ssb = band_helper.get_abs_freq_ssb_arfcn(
cfg.band, srsran_subcarrier_spacing_30kHz, cfg.phy_cell.carrier.dl_absolute_frequency_point_a);
}
phy_cfg_->phy_cell_cfg_nr.push_back(cfg.phy_cell);
}

48
srsenb/src/stack/rrc/rrc_nr.cc
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@ -14,7 +14,6 @@
#include "srsenb/hdr/common/common_enb.h"
#include "srsenb/test/mac/nr/sched_nr_cfg_generators.h"
#include "srsran/asn1/rrc_nr_utils.h"
#include "srsran/common/band_helper.h"
#include "srsran/common/common_nr.h"
#include "srsran/common/phy_cfg_nr_default.h"
#include "srsran/common/standard_streams.h"
@ -1130,35 +1129,10 @@ int rrc_nr::ue::pack_recfg_with_sync_sp_cell_cfg_common_dl_cfg_common_freq_info_
{
cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.dl_cfg_common.freq_info_dl_present = true;
auto& freq_info_dl = cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.dl_cfg_common.freq_info_dl;
freq_info_dl.freq_band_list.push_back(parent->cfg.cell_list[0].band);
srsran::srsran_band_helper band_helper;
freq_info_dl.absolute_freq_point_a = band_helper.get_abs_freq_point_a_arfcn(
parent->cfg.cell_list[0].phy_cell.carrier.nof_prb, parent->cfg.cell_list[0].dl_arfcn);
freq_info_dl.absolute_freq_point_a = parent->cfg.cell_list[0].phy_cell.carrier.dl_absolute_frequency_point_a;
freq_info_dl.absolute_freq_ssb_present = true;
uint32_t absolute_freq_ssb;
if (parent->cfg.cell_list[0].duplex_mode == SRSRAN_DUPLEX_MODE_FDD) {
if (parent->cfg.cell_list[0].band == 3) { // band n3
absolute_freq_ssb = 367930;
} else if (parent->cfg.cell_list[0].band == 5) { // band n5
absolute_freq_ssb = 176210;
} else if (parent->cfg.cell_list[0].band == 7) { // band n7
absolute_freq_ssb = 529470;
} else {
parent->logger.error("Unsupported dl_arfcn.");
return SRSRAN_ERROR;
}
} else {
if (parent->cfg.cell_list[0].band == 78) { // band n78
absolute_freq_ssb = 634176;
} else {
parent->logger.error("Unsupported dl_arfcn.");
return SRSRAN_ERROR;
}
}
cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.dl_cfg_common.freq_info_dl.absolute_freq_ssb =
absolute_freq_ssb; // TODO: calculate from actual DL ARFCN
freq_info_dl.absolute_freq_ssb = parent->cfg.cell_list[0].phy_cell.carrier.absolute_frequency_ssb;
freq_info_dl.scs_specific_carrier_list.resize(1);
auto& dl_carrier = freq_info_dl.scs_specific_carrier_list[0];
@ -1284,19 +1258,13 @@ int rrc_nr::ue::pack_recfg_with_sync_sp_cell_cfg_common_dl_cfg_common(
int rrc_nr::ue::pack_recfg_with_sync_sp_cell_cfg_common_ul_cfg_common_freq_info_ul(
asn1::rrc_nr::cell_group_cfg_s& cell_group_cfg_pack)
{
srsran::srsran_band_helper band_helper;
cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.ul_cfg_common.freq_info_ul_present = true;
cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.ul_cfg_common.freq_info_ul.freq_band_list
.push_back(parent->cfg.cell_list[0].band);
cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.ul_cfg_common.freq_info_ul.absolute_freq_point_a =
band_helper.get_abs_freq_point_a_arfcn(parent->cfg.cell_list[0].phy_cell.carrier.nof_prb,
parent->cfg.cell_list[0].ul_arfcn);
;
cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.ul_cfg_common.freq_info_ul
.scs_specific_carrier_list.resize(1);
auto& ul_carrier = cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.ul_cfg_common.freq_info_ul
.scs_specific_carrier_list[0];
auto& freq_info_ul = cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.ul_cfg_common.freq_info_ul;
freq_info_ul.freq_band_list.push_back(parent->cfg.cell_list[0].band);
freq_info_ul.absolute_freq_point_a = parent->cfg.cell_list[0].phy_cell.carrier.ul_absolute_frequency_point_a;
freq_info_ul.scs_specific_carrier_list.resize(1);
auto& ul_carrier = freq_info_ul.scs_specific_carrier_list[0];
ul_carrier.offset_to_carrier = 0;
ul_carrier.subcarrier_spacing = subcarrier_spacing_opts::khz15;
ul_carrier.carrier_bw = 52;

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