Merge remote-tracking branch 'origin/NR_fix_ssbpos_ho' into integration_2026_w10 (!3929)

UE: Fix if target cell during handover has SSB at a different offset as in source cell

These changes fixed these observed issues:
- If target cell has a different SSB position compared to source cell during
  ho - sync was not successful.
- RAR does not get decoded if SSB position has changed on the target cell
  compared to source cell.

executables/nr-ue.c

@@ -486,12 +486,13 @@ static int handle_sync_req_from_mac(PHY_VARS_NR_UE *UE)
       UE->UE_scan_carrier = false;
     UE->target_Nid_cell = UE->synch_request.synch_req.target_Nid_cell;
 
-    const fapi_nr_ue_carrier_config_t *cfg = &UE->nrUE_config.carrier_config;
+    const fapi_nr_config_request_t *config = &UE->nrUE_config;
+    const fapi_nr_ue_carrier_config_t *cfg = &config->carrier_config;
     uint64_t dl_CarrierFreq = get_carrier_frequency(fp->N_RB_DL, fp->numerology_index, cfg->dl_frequency);
     uint64_t ul_CarrierFreq = get_carrier_frequency(fp->N_RB_UL, fp->numerology_index, cfg->uplink_frequency);
     if (dl_CarrierFreq != fp->dl_CarrierFreq || ul_CarrierFreq != fp->ul_CarrierFreq) {
       LOG_I(NR_PHY,
-            "[UE %d] RF frequency change: dl %lu->%lu Hz, ul %lu->%lu Hz (from dl_frequency=%u kHz, target_Nid_cell=%d)\n",
+            "[UE %d] SYNC REQ: RF frequency change: dl %lu->%lu Hz, ul %lu->%lu Hz (from dl_frequency=%u kHz, target_Nid_cell=%d)\n",
             UE->Mod_id,
             fp->dl_CarrierFreq,
             dl_CarrierFreq,
@@ -505,6 +506,16 @@ static int handle_sync_req_from_mac(PHY_VARS_NR_UE *UE)
       init_symbol_rotation(fp);
     }
 
+    int ssb_start_subcarrier = nr_get_ssb_start_sc(fp->numerology_index,
+                                                   config->ssb_table.ssb_offset_point_a,
+                                                   config->ssb_table.ssb_subcarrier_offset,
+                                                   fp->freq_range);
+    // SSB location can change during for ex: handover on the target cell
+    if (ssb_start_subcarrier != fp->ssb_start_subcarrier) {
+      fp->ssb_start_subcarrier = ssb_start_subcarrier;
+      LOG_I(NR_PHY, "SYNC REQ: SSB location changed:%d\n", fp->ssb_start_subcarrier);
+    }
+
     // Apply Doppler based on NTN-Config for target cell
     if (UE->nrUE_config.ntn_config.is_targetcell)
       apply_ntn_timing_advance_and_doppler(UE, fp, -1);

openair1/PHY/INIT/nr_parms.c

@@ -24,6 +24,7 @@
 #include "common/utils/LOG/log.h"
 #include "executables/softmodem-common.h"
 #include "PHY/MODULATION/nr_modulation.h"
+#include "PHY/nr_phy_common/inc/nr_phy_common.h"
 
 /// Subcarrier spacings in Hz indexed by numerology index
 static const uint32_t nr_subcarrier_spacing[MAX_NUM_SUBCARRIER_SPACING] = {15e3, 30e3, 60e3, 120e3, 240e3};
@@ -421,16 +422,11 @@ int nr_init_frame_parms_ue(NR_DL_FRAME_PARMS *fp, fapi_nr_config_request_t* conf
   fp->samples_per_frame = 10 * fp->samples_per_subframe;
   fp->freq_range = get_freq_range_from_freq(fp->dl_CarrierFreq);
 
-  uint8_t sco = 0;
-  if (((fp->freq_range == FR1) && (config->ssb_table.ssb_subcarrier_offset < 24)) ||
-      ((fp->freq_range == FR2) && (config->ssb_table.ssb_subcarrier_offset < 12))) {
-    if (fp->freq_range == FR1)
-      sco = config->ssb_table.ssb_subcarrier_offset>>config->ssb_config.scs_common;
-    else
-      sco = config->ssb_table.ssb_subcarrier_offset;
-  }
+  fp->ssb_start_subcarrier = nr_get_ssb_start_sc(config->ssb_config.scs_common,
+                                                 config->ssb_table.ssb_offset_point_a,
+                                                 config->ssb_table.ssb_subcarrier_offset,
+                                                 fp->freq_range);
 
-  fp->ssb_start_subcarrier = (12 * config->ssb_table.ssb_offset_point_a + sco);
   set_Lmax(fp);
 
   fp->L_ssb = (((uint64_t) config->ssb_table.ssb_mask_list[0].ssb_mask)<<32) | config->ssb_table.ssb_mask_list[1].ssb_mask;

openair1/PHY/nr_phy_common/inc/nr_phy_common.h

@@ -389,4 +389,9 @@ void nr_generate_csi_rs(const NR_DL_FRAME_PARMS *frame_parms,
                         const uint8_t cdm_type,
                         c16_t **dataF);
 
+int nr_get_ssb_start_sc(int scs,
+                        int ssb_offset_point_a,
+                        int ssb_sco,
+                        frequency_range_t freq_range);
+
 #endif

openair1/PHY/nr_phy_common/src/nr_phy_common.c

@@ -481,3 +481,26 @@ void nr_fo_compensation(double fo_Hz, int samples_per_ms, int sample_offset, con
   mult_complex_vectors(rxdata_in, rot, rxdata_out, size, 14);
 #endif
 }
+
+/*!
+* Setting the first subcarrier
+* 3GPP TS 38.211 sections 7.4.3.1 and 4.4.4.2
+* for FR1 offsetToPointA and k_SSB are expressed in terms of 15 kHz SCS
+* for FR2 offsetToPointA is expressed in terms of 60 kHz SCS and k_SSB expressed in terms of the SCS provided
+* by the higher-layer parameter subCarrierSpacingCommon
+*/
+int nr_get_ssb_start_sc(int scs, int ssb_offset_point_a, int ssb_sco, frequency_range_t freq_range)
+{
+  const int prb_offset =
+      (freq_range == FR1) ? ssb_offset_point_a >> scs : ssb_offset_point_a >> (scs - 2);
+  const int sc_offset =
+      (freq_range == FR1) ? ssb_sco >> scs : ssb_sco;
+
+  int ssb_start_subcarrier = (12 * prb_offset + sc_offset);
+
+  LOG_D(NR_PHY, "prb_offset:%d, ssb_subcarrier_offset:%d,scs :%d, Fr:%d, ssb_start_subcarrier:%d\n",
+                        prb_offset, ssb_sco, scs, freq_range, ssb_start_subcarrier);
+
+  return ssb_start_subcarrier;
+
+}

openair1/SCHED_NR/phy_procedures_nr_gNB.c

@@ -118,9 +118,10 @@ void nr_common_signal_procedures(PHY_VARS_gNB *gNB, int frame, int slot, const n
   // by the higher-layer parameter subCarrierSpacingCommon
   nfapi_nr_config_request_scf_t *cfg = &gNB->gNB_config;
   const int scs = cfg->ssb_config.scs_common.value;
-  const int prb_offset = (fp->freq_range == FR1) ? pdu->ssbOffsetPointA >> scs : pdu->ssbOffsetPointA >> (scs - 2);
-  const int sc_offset = (fp->freq_range == FR1) ? pdu->SsbSubcarrierOffset >> scs : pdu->SsbSubcarrierOffset;
-  fp->ssb_start_subcarrier = (12 * prb_offset + sc_offset);
+  fp->ssb_start_subcarrier = nr_get_ssb_start_sc(scs,
+                                                 pdu->ssbOffsetPointA,
+                                                 pdu->SsbSubcarrierOffset,
+                                                 fp->freq_range);
 
   if (fp->print_ue_help_cmdline_log && IS_SA_MODE(get_softmodem_params())) {
     fp->print_ue_help_cmdline_log = false;
@@ -142,15 +143,6 @@ void nr_common_signal_procedures(PHY_VARS_gNB *gNB, int frame, int slot, const n
             fp->ssb_start_subcarrier,
             fp->threequarter_fs ? "-E" : "");
   }
-  LOG_D(PHY,
-        "ssbOffsetPointA %d SSB SsbSubcarrierOffset %d  prb_offset %d sc_offset %d scs %d ssb_start_subcarrier %d\n",
-        pdu->ssbOffsetPointA,
-        pdu->SsbSubcarrierOffset,
-        prb_offset,
-        sc_offset,
-        scs,
-        fp->ssb_start_subcarrier);
-
   LOG_D(PHY,"SS TX: frame %d, slot %d, start_symbol %d\n", frame, slot, ssb_start_symbol);
   const nfapi_nr_tx_precoding_and_beamforming_t *pb = &pdu->precoding_and_beamforming;
   c16_t ***txdataF = gNB->common_vars.txdataF;

openair2/LAYER2/NR_MAC_UE/config_ue.c

@@ -537,16 +537,15 @@ static void config_common_ue(NR_UE_MAC_INST_t *mac, NR_ServingCellConfigCommon_t
 
   // SSB Table config
   if (frequencyInfoDL && frequencyInfoDL->absoluteFrequencySSB) {
-    int scs_scaling = 1 << (cfg->ssb_config.scs_common);
-    if (frequencyInfoDL->absoluteFrequencyPointA < 600000)
-      scs_scaling = scs_scaling * 3;
-    if (frequencyInfoDL->absoluteFrequencyPointA > 2016666)
-      scs_scaling = scs_scaling >> 2;
-    uint32_t absolute_diff = (*frequencyInfoDL->absoluteFrequencySSB - frequencyInfoDL->absoluteFrequencyPointA);
-    cfg->ssb_table.ssb_offset_point_a = absolute_diff / (12 * scs_scaling) - 10;
+    cfg->ssb_table.ssb_offset_point_a = get_ssb_offset_to_pointA(*frequencyInfoDL->absoluteFrequencySSB,
+                                                                 frequencyInfoDL->absoluteFrequencyPointA,
+                                                                 cfg->ssb_config.scs_common,
+                                                                 mac->frequency_range);
     cfg->ssb_table.ssb_period = *scc->ssb_periodicityServingCell;
     // NSA -> take ssb offset from SCS
-    cfg->ssb_table.ssb_subcarrier_offset = absolute_diff % (12 * scs_scaling);
+    cfg->ssb_table.ssb_subcarrier_offset = get_ssb_subcarrier_offset(*frequencyInfoDL->absoluteFrequencySSB,
+                                                                     frequencyInfoDL->absoluteFrequencyPointA,
+                                                                     cfg->ssb_config.scs_common);
     cfg->ssb_table.ssb_case = set_ssb_case(*scc->ssbSubcarrierSpacing, mac->nr_band);
   }
 
@@ -2107,18 +2106,24 @@ static void handle_reconfiguration_with_sync(NR_UE_MAC_INST_t *mac,
       configure_common_BWP_dl(mac, bwp_id, scc->downlinkConfigCommon->initialDownlinkBWP);
     if (scc->uplinkConfigCommon)
       configure_common_BWP_ul(mac, bwp_id, scc->uplinkConfigCommon->initialUplinkBWP);
+
+    // Update PDCCH config as MAC configuration has changed
+    if (IS_SA_MODE(get_softmodem_params()))
+      update_pdcch_config(mac);
   }
 
   mac->state = UE_NOT_SYNC_RECONF;
   ra->ra_state = nrRA_UE_IDLE;
   nr_ue_mac_default_configs(mac);
 
+  // PHY CONFIG request should be sent, ahead of SYNC request
+  // As SYNC request processes the new config
+  mac->if_module->phy_config_request(&mac->phy_config);
+  mac->phy_config.config_req.ntn_config.params_changed = false;
   mac->synch_request.Mod_id = mac->ue_id;
   mac->synch_request.CC_id = cc_idP;
   mac->synch_request.synch_req.target_Nid_cell = mac->physCellId;
   mac->if_module->synch_request(&mac->synch_request);
-  mac->if_module->phy_config_request(&mac->phy_config);
-  mac->phy_config.config_req.ntn_config.params_changed = false;
 }
 
 static void configure_physicalcellgroup(NR_UE_MAC_INST_t *mac,

openair2/LAYER2/NR_MAC_UE/mac_proto.h

@@ -377,4 +377,5 @@ void nr_ue_sidelink_scheduler(nr_sidelink_indication_t *sl_ind, NR_UE_MAC_INST_t
 
 NR_SearchSpace_t *get_common_search_space(const NR_UE_MAC_INST_t *mac, const NR_SearchSpaceId_t ss_id);
 ssb_ro_preambles_t get_ssb_ro_preambles_4step(struct NR_RACH_ConfigCommon__ssb_perRACH_OccasionAndCB_PreamblesPerSSB *config);
+void update_pdcch_config(NR_UE_MAC_INST_t *mac);
 #endif

openair2/LAYER2/NR_MAC_UE/nr_ue_dci_configuration.c

@@ -422,6 +422,38 @@ static bool monitor_dci_for_other_SI(NR_UE_MAC_INST_t *mac,
   return false;
 }
 
+void update_pdcch_config(NR_UE_MAC_INST_t *mac)
+{
+  int scs = mac->current_DL_BWP ? mac->current_DL_BWP->scs : mac->numerology;
+  const int slots_per_frame = get_slots_per_frame_from_scs(scs);
+  int ssb_sc_offset_norm;
+  if (mac->ssb_subcarrier_offset < 24 && mac->frequency_range == FR1)
+    ssb_sc_offset_norm = mac->ssb_subcarrier_offset >> scs;
+  else
+    ssb_sc_offset_norm = mac->ssb_subcarrier_offset;
+  uint16_t ssb_offset_point_a = (mac->ssb_start_subcarrier - ssb_sc_offset_norm) / 12;
+  int ssb_start_symbol = get_ssb_start_symbol(mac->nr_band, scs, mac->mib_ssb);
+  get_type0_PDCCH_CSS_config_parameters(&mac->type0_PDCCH_CSS_config,
+                                        mac->mib_frame,
+                                        mac->mib,
+                                        slots_per_frame,
+                                        ssb_sc_offset_norm,
+                                        ssb_start_symbol,
+                                        scs,
+                                        mac->frequency_range,
+                                        mac->nr_band,
+                                        273,  // at this point UE in principle doesn't know the grid size (we assume the largest)
+                                        mac->mib_ssb,
+                                        1, // If the UE is not configured with a periodicity, the UE assumes a periodicity of a half frame
+                                        ssb_offset_point_a);
+  if (mac->search_space_zero == NULL)
+    mac->search_space_zero = calloc(1, sizeof(*mac->search_space_zero));
+  if (mac->coreset0 == NULL)
+    mac->coreset0 = calloc(1, sizeof(*mac->coreset0));
+  fill_coresetZero(mac->coreset0, &mac->type0_PDCCH_CSS_config);
+  fill_searchSpaceZero(mac->search_space_zero, slots_per_frame, &mac->type0_PDCCH_CSS_config);
+}
+
 void ue_dci_configuration(NR_UE_MAC_INST_t *mac, fapi_nr_dl_config_request_t *dl_config, const frame_t frame, const int slot)
 {
   const NR_UE_DL_BWP_t *current_DL_BWP = mac->current_DL_BWP;
@@ -430,37 +462,14 @@ void ue_dci_configuration(NR_UE_MAC_INST_t *mac, fapi_nr_dl_config_request_t *dl
   int scs = current_DL_BWP ? current_DL_BWP->scs : mac->numerology;
   const int slots_per_frame = get_slots_per_frame_from_scs(scs);
   if (mac->get_sib1) {
-    int ssb_sc_offset_norm;
-    if (mac->ssb_subcarrier_offset < 24 && mac->frequency_range == FR1)
-      ssb_sc_offset_norm = mac->ssb_subcarrier_offset >> scs;
-    else
-      ssb_sc_offset_norm = mac->ssb_subcarrier_offset;
-    uint16_t ssb_offset_point_a = (mac->ssb_start_subcarrier - ssb_sc_offset_norm) / 12;
-    int ssb_start_symbol = get_ssb_start_symbol(mac->nr_band, scs, mac->mib_ssb);
-    get_type0_PDCCH_CSS_config_parameters(&mac->type0_PDCCH_CSS_config,
-                                          mac->mib_frame,
-                                          mac->mib,
-                                          slots_per_frame,
-                                          ssb_sc_offset_norm,
-                                          ssb_start_symbol,
-                                          scs,
-                                          mac->frequency_range,
-                                          mac->nr_band,
-                                          273,  // at this point UE in principle doesn't know the grid size (we assume the largest)
-                                          mac->mib_ssb,
-                                          1, // If the UE is not configured with a periodicity, the UE assumes a periodicity of a half frame
-                                          ssb_offset_point_a);
-    if (mac->search_space_zero == NULL)
-      mac->search_space_zero = calloc(1, sizeof(*mac->search_space_zero));
-    if (mac->coreset0 == NULL)
-      mac->coreset0 = calloc(1, sizeof(*mac->coreset0));
-    fill_coresetZero(mac->coreset0, &mac->type0_PDCCH_CSS_config);
-    fill_searchSpaceZero(mac->search_space_zero, slots_per_frame, &mac->type0_PDCCH_CSS_config);
-    if (is_ss_monitor_occasion(frame, slot, slots_per_frame, mac->search_space_zero)) {
+    update_pdcch_config(mac);
+    bool is_occasion = is_ss_monitor_occasion(frame, slot, slots_per_frame, mac->search_space_zero);
+    if (is_occasion) {
       LOG_D(NR_MAC_DCI, "Monitoring DCI for SIB1 in frame %d slot %d\n", frame, slot);
       config_dci_pdu(mac, dl_config, TYPE_SI_RNTI_, slot, mac->search_space_zero);
     }
   }
+
   for (int i = 0; i < MAX_SI_GROUPS; i++) {
     if (!mac->get_otherSI[i])
       continue;