Calculate ssb frequency from freqency point a.

lib/include/srsran/common/band_helper.h

@@ -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:

lib/src/common/band_helper.cc

@@ -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

srsenb/src/enb_cfg_parser.cc

@@ -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);
   }
 

srsenb/src/stack/rrc/rrc_nr.cc

@@ -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     = parent->cfg.cell_list[0].phy_cell.carrier.dl_absolute_frequency_point_a;
-  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_ssb_present = true;
-
+  freq_info_dl.absolute_freq_ssb         = parent->cfg.cell_list[0].phy_cell.carrier.absolute_frequency_ssb;
-  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.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
+  auto& freq_info_ul = cell_group_cfg_pack.sp_cell_cfg.recfg_with_sync.sp_cell_cfg_common.ul_cfg_common.freq_info_ul;
-      .push_back(parent->cfg.cell_list[0].band);
+  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 =
+  freq_info_ul.absolute_freq_point_a = parent->cfg.cell_list[0].phy_cell.carrier.ul_absolute_frequency_point_a;
-      band_helper.get_abs_freq_point_a_arfcn(parent->cfg.cell_list[0].phy_cell.carrier.nof_prb,
+  freq_info_ul.scs_specific_carrier_list.resize(1);
-                                             parent->cfg.cell_list[0].ul_arfcn);
+
-  ;
+  auto& ul_carrier              = freq_info_ul.scs_specific_carrier_list[0];
-  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];
   ul_carrier.offset_to_carrier  = 0;
   ul_carrier.subcarrier_spacing = subcarrier_spacing_opts::khz15;
   ul_carrier.carrier_bw         = 52;