srsue,phy: support n_ta_offset parameter from sib1

lib/include/srsran/common/phy_cfg_nr.h

@@ -45,7 +45,8 @@ struct phy_cfg_nr_t {
   srsran_harq_ack_cfg_hl_t  harq_ack = {};
   srsran_csi_hl_cfg_t       csi      = {};
   srsran_carrier_nr_t       carrier  = {};
-  ssb_cfg_t                 ssb;
+  ssb_cfg_t                 ssb      = {};
+  uint32_t                  t_offset = 0; ///< n-TimingAdvanceOffset
 
   phy_cfg_nr_t() {}
 

srsue/hdr/phy/nr/sync_sa.h

@@ -81,6 +81,7 @@ public:
 
   void add_ta_cmd_rar(uint32_t tti, uint32_t ta_cmd);
   void add_ta_cmd_new(uint32_t tti, uint32_t ta_cmd);
+  void add_ta_offset(uint32_t ta_offset);
 
 private:
   stack_interface_phy_nr*      stack = nullptr; ///< Stand-Alone RRC interface

srsue/hdr/phy/ta_control.h

@@ -95,6 +95,19 @@ public:
                 next_base_sec * 1e6f);
   }
 
+  void add_ta_offset(uint32_t ta_offset)
+  {
+    std::lock_guard<std::mutex> lock(mutex);
+
+    // Assuming numerology 0
+    next_base_nta = ta_offset / 64;
+
+    // Update base in seconds
+    next_base_sec = static_cast<float>(next_base_nta) * SRSRAN_LTE_TS;
+
+    logger.info("PHY:   Set TA offset: n_ta_offset: %d, ta_usec: %.1f", next_base_nta, next_base_sec * 1e6f);
+  }
+
   /**
    * Increments (delta) the next base time according to time alignment command from a Random Access Response (RAR).
    *

srsue/src/phy/phy_nr_sa.cc

@@ -258,6 +258,9 @@ bool phy_nr_sa::set_config(const srsran::phy_cfg_nr_t& cfg)
     // Set UE configuration
     bool ret = workers.set_config(config_nr);
 
+    // Pass n_ta_offset to sync
+    sync.add_ta_offset(config_nr.t_offset);
+
     // Notify PHY config completion
     if (stack != nullptr) {
       stack->set_phy_config_complete(ret);

srsue/src/phy/sync_sa.cc

@@ -93,6 +93,11 @@ void sync_sa::add_ta_cmd_new(uint32_t tti_, uint32_t ta_cmd)
   ta.add_ta_cmd_new(tti_, ta_cmd);
 }
 
+void sync_sa::add_ta_offset(uint32_t ta_offset)
+{
+  ta.add_ta_offset(ta_offset);
+}
+
 void sync_sa::cell_go_idle()
 {
   std::unique_lock<std::mutex> ul(rrc_mutex);

srsue/src/stack/rrc_nr/rrc_nr.cc

@@ -486,6 +486,26 @@ void rrc_nr::handle_sib1(const sib1_s& sib1)
   // Apply SSB Config
   fill_phy_ssb_cfg(sib1.serving_cell_cfg_common, &phy_cfg.ssb);
 
+  // Apply n-TimingAdvanceOffset
+  if (sib1.serving_cell_cfg_common.n_timing_advance_offset_present) {
+    switch (sib1.serving_cell_cfg_common.n_timing_advance_offset.value) {
+      case serving_cell_cfg_common_sib_s::n_timing_advance_offset_opts::n0:
+        phy_cfg.t_offset = 0;
+        break;
+      case serving_cell_cfg_common_sib_s::n_timing_advance_offset_opts::n25600:
+        phy_cfg.t_offset = 25600;
+        break;
+      case serving_cell_cfg_common_sib_s::n_timing_advance_offset_opts::n39936:
+        phy_cfg.t_offset = 39936;
+        break;
+      default:
+        logger.error("Invalid n_ta_offset option");
+        break;
+    }
+  } else {
+    phy_cfg.t_offset = 25600;
+  }
+
   phy_cfg_state = PHY_CFG_STATE_SA_SIB_CFG;
   if (not phy->set_config(phy_cfg)) {
     logger.warning("Could not set phy config.");