Addition of PRACH TA correction

lib/include/srslte/interfaces/ue_interfaces.h

@@ -544,8 +544,8 @@ public:
   /* Configure PRACH using parameters written by RRC */
   virtual void configure_prach_params() = 0;
 
-  virtual void         prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm) = 0;
-  virtual prach_info_t prach_get_info()                                                                = 0;
+  virtual void prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm, float ta_base_sec) = 0;
+  virtual prach_info_t prach_get_info()                                                                           = 0;
 
   /* Indicates the transmission of a SR signal in the next opportunity */
   virtual void sr_send()        = 0;

srsue/hdr/phy/phy.h

@@ -85,7 +85,7 @@ public:
   void configure_prach_params() final;
 
   /* Transmits PRACH in the next opportunity */
-  void         prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm) final;
+  void         prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm, float ta_base_sec) final;
   prach_info_t prach_get_info() final;
 
   /* Indicates the transmission of a SR signal in the next opportunity */
@@ -158,6 +158,7 @@ private:
 
   /* Current time advance */
   uint32_t n_ta = 0;
+  uint32_t n_ta_base = 0;
 
   static void set_default_args(phy_args_t& args);
   bool check_args(const phy_args_t& args);

srsue/src/phy/phy.cc

@@ -259,6 +259,7 @@ void phy::get_metrics(phy_metrics_t* m)
 void phy::set_timeadv_rar(uint32_t ta_cmd)
 {
   n_ta = srslte_N_ta_new_rar(ta_cmd);
+  n_ta += n_ta_base;
   sfsync.set_time_adv_sec(((float)n_ta) * SRSLTE_LTE_TS);
   Info("PHY:   Set TA RAR: ta_cmd: %d, n_ta: %d, ta_usec: %.1f\n", ta_cmd, n_ta, ((float)n_ta) * SRSLTE_LTE_TS * 1e6);
 }
@@ -339,10 +340,11 @@ float phy::get_pathloss_db()
   return common.cur_pathloss;
 }
 
-void phy::prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm)
+void phy::prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm, float ta_base_sec)
 {
-  n_ta = 0;
-  sfsync.set_time_adv_sec(0.0f);
+  n_ta      = 0; /* Reset Time aligment */
+  n_ta_base = (uint32_t)roundf(ta_base_sec / SRSLTE_LTE_TS);
+  sfsync.set_time_adv_sec(ta_base_sec);
   common.reset_radio();
   if (!prach_buffer.prepare_to_send(preamble_idx, allowed_subframe, target_power_dbm)) {
     Error("Preparing PRACH to send\n");
@@ -370,6 +372,7 @@ void phy::reset()
 {
   Info("Resetting PHY\n");
   n_ta = 0;
+  n_ta_base = 0;
   sfsync.set_time_adv_sec(0);
   for (uint32_t i = 0; i < nof_workers; i++) {
     workers[i]->reset();

srsue/src/stack/mac/proc_ra.cc

@@ -343,7 +343,7 @@ void ra_proc::preamble_transmission()
   received_target_power_dbm = rach_cfg.iniReceivedTargetPower + delta_preamble_db +
                               (preambleTransmissionCounter - 1) * rach_cfg.powerRampingStep;
 
-  phy_h->prach_send(sel_preamble, sel_maskIndex - 1, received_target_power_dbm);
+  phy_h->prach_send(sel_preamble, sel_maskIndex - 1, received_target_power_dbm, 0.0f);
   rntis->rar_rnti        = 0;
   ra_tti                 = 0;
   rar_received           = false;

srsue/test/mac_test.cc

@@ -123,7 +123,7 @@ public:
   // phy_interface_mac_lte
   void configure_prach_params(){};
 
-  void prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm)
+  void prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm, float ta_base_sec)
   {
     prach_delay_cnt   = 0;
     last_preamble_idx = preamble_idx;

srsue/test/phy/ue_phy_test.cc

@@ -501,7 +501,7 @@ int main(int argc, char** argv)
 
   // 3. Transmit PRACH
   phy_test->get_phy_interface_mac()->configure_prach_params();
-  phy_test->get_phy_interface_mac()->prach_send(0, -1, 0.0f);
+  phy_test->get_phy_interface_mac()->prach_send(0, -1, 0.0f, 0.0f);
   TESTASSERT(phy_test->get_radio()->wait_tx(default_timeout, false));
 
   // 4. Configure RNTI with PUCCH and check transmission

srsue/test/ttcn3/hdr/lte_ttcn3_phy.h

@@ -93,7 +93,7 @@ public:
 
   // phy_interface_mac_lte
   void         configure_prach_params();
-  void         prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm);
+  void         prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm, float ta_base_sec);
   prach_info_t prach_get_info();
   void         sr_send();
   int          sr_last_tx_tti();

srsue/test/ttcn3/src/lte_ttcn3_phy.cc

@@ -194,7 +194,7 @@ void lte_ttcn3_phy::configure_prach_params()
   log.debug("%s not implemented.\n", __FUNCTION__);
 };
 
-void lte_ttcn3_phy::prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm)
+void lte_ttcn3_phy::prach_send(uint32_t preamble_idx, int allowed_subframe, float target_power_dbm, float ta_base_sec)
 {
   log.info("Sending PRACH with preamble %d on PCID=%d\n", preamble_idx, pcell.info.id);
   prach_tti_tx = current_tti;