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.

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;