[develop] Added: timing offset estimation based on PBCH

    - command-line option to activate/deactivate compensation added

executables/nr-softmodem-common.h

@@ -120,6 +120,7 @@
 #define CONFIG_HLP_TDRIFT        "Set the timing offset/drift per frame in the RF simulator (expressed in number of samples per frame)\n"
 #define CONFIG_HLP_FDopplerRate  "Set the Doppler rate in Hz/s\n"
 #define CONFIG_HLP_FDopplerVar   "Set Doppler variance, [fdoppler +/- fdopplerVar]\n"
+#define CONFIG_HLP_TDriftComp    "Execute continous timing drift compensation\n"
 /*--------------------------------------------------------------------------------------------------------------------------------*/
 /*                                            command line parameters for LOG utility                                             */
 /*   optname         helpstr          paramflags          XXXptr                     defXXXval            type           numelt   */
@@ -174,5 +175,6 @@ extern int fdopplerComp;         // flag to activate/deactivate continous freque
 extern int RFsim_DriftPerFrame; //the timing offset/drift per frame in the RF simulator (expressed in number of samples per frame)
 extern int32_t fdopplerRate; //Doppler rate in Hz/s
 extern uint32_t fdopplerVar; //Doppler variance, [fdoppler +/- fdopplerVar]
+extern int tdriftComp;         // flag to activate/deactivate continous timing drift compensation
 
 #endif

executables/nr-softmodem.c

@@ -576,6 +576,7 @@ int fdopplerComp = 1;
 int RFsim_DriftPerFrame = 0;
 int32_t fdopplerRate;
 uint32_t fdopplerVar;
+int tdriftComp = 1;
 
 int main( int argc, char **argv ) {
   int ru_id, CC_id = 0;

executables/nr-uesoftmodem.c

@@ -432,6 +432,7 @@ int32_t fdoppler = 0; //center Doppler frequency shift
 int32_t fdopplerRate; //Doppler rate in Hz/s
 uint32_t fdopplerVar; //Doppler variance, [fdoppler +/- fdopplerVar]
 int fdopplerComp = 1; // flag to activate continous frequency offset compensation (=0 deacticated, =1 activated (default case))
+int tdriftComp = 1;
 
 
 int main( int argc, char **argv ) {

executables/nr-uesoftmodem.h

@@ -68,9 +68,10 @@
   {"ue_k2" ,                       CONFIG_HLP_UEK2,            0,               .u16ptr=&NTN_UE_k2,                          .defintval=0,      TYPE_UINT16,   0}, \
   {"FD" ,                          CONFIG_HLP_FDoppler,    0,                   .iptr=&fdoppler,                             .defintval=0,      TYPE_INT,      0}, \
   {"FC" ,                          CONFIG_HLP_FDopplerComp,    0,               .iptr=&fdopplerComp,                         .defintval=1,      TYPE_INT,      0}, \
-  {"TD" ,                           CONFIG_HLP_TDRIFT,      0,                   .iptr=&RFsim_DriftPerFrame,                  .defintval=0,      TYPE_INT,      0}, \
+  {"TD" ,                          CONFIG_HLP_TDRIFT,      0,                   .iptr=&RFsim_DriftPerFrame,                  .defintval=0,      TYPE_INT,      0}, \
   {"DSR" ,                         CONFIG_HLP_FDopplerRate,0,                   .iptr=&fdopplerRate,                         .defintval=0,      TYPE_INT32,    0}, \
   {"DSV" ,                         CONFIG_HLP_FDopplerVar, 0,                   .uptr=&fdopplerVar,                          .defintval=0,      TYPE_UINT32,   0}, \
+  {"TC" ,                          CONFIG_HLP_TDriftComp,    0,                 .iptr=&tdriftComp,                           .defintval=1,      TYPE_INT,    0}, \
 }
 // clang-format on
 

openair1/PHY/NR_UE_ESTIMATION/nr_adjust_synch_ue.c

@@ -50,6 +50,11 @@ void nr_adjust_synch_ue(NR_DL_FRAME_PARMS *frame_parms,
   const int sync_pos = 0;
   uint8_t sync_offset = 0;
 
+  static int64_t TO_I_Ctrl = 0; //Integral controller for TO
+  int I_ScalingF = 10; //Scaling factor for the I controller, can be adjusted
+  static int frameLast = 0; //frame number of last call of nr_adjust_synch_ue()
+  static int FirstFlag = 1; //indicate the first call of nr_adjust_synch_ue()
+
   VCD_SIGNAL_DUMPER_DUMP_FUNCTION_BY_NAME(VCD_SIGNAL_DUMPER_FUNCTIONS_UE_ADJUST_SYNCH, VCD_FUNCTION_IN);
 
   short ncoef = 32767 - coef;
@@ -83,16 +88,33 @@ void nr_adjust_synch_ue(NR_DL_FRAME_PARMS *frame_parms,
   //ue->max_pos_fil = max_pos << 15;
 
   int diff = (ue->max_pos_fil >> 15) - sync_pos;
+  int FrameDiff = (frame-frameLast+1024)%1024;
 
-  if (frame_parms->freq_range==nr_FR2) 
-    sync_offset = 2;
+  if (FirstFlag)
+    FirstFlag = 0;
   else
-    sync_offset = 0;
+    diff /= FrameDiff; //scaled by the frame number
+
+  frameLast = frame; //save the last frame number
+
+  TO_I_Ctrl += diff; //integral of all offsets
+  ue->rx_offset = diff;
+  ue->rx_offset_TO = diff+TO_I_Ctrl/I_ScalingF; //PI controller
+  ue->rx_offset_slot = 1;
+  ue->rx_offset_comp = 0;
+
+  printf("** Frame: %u, ue->rx_offset: %d, ue->rx_offset_TO: %d\n", frame, ue->rx_offset, ue->rx_offset_TO);
 
-  if ( abs(diff) < (SYNCH_HYST+sync_offset) )
+  extern tdriftComp;
+  {
+    TO_I_Ctrl += diff; //integral of all offsets
     ue->rx_offset = 0;
-  else
-    ue->rx_offset = diff;
+    ue->rx_offset_TO = 0; //PI controller
+    ue->rx_offset_slot = 1;
+    ue->rx_offset_comp = 0;
+  }
+
+  if (tdriftComp == 0)
 
   const int sample_shift = -(ue->rx_offset>>1);
   // reset IIR filter for next offset calculation

openair1/PHY/defs_nr_UE.h

@@ -525,6 +525,9 @@ typedef struct {
   int64_t          max_pos_fil;    /// Timing offset IIR filter
   bool             apply_timing_offset;     /// Do time sync for current frame
   int              time_sync_cell;
+  int              rx_offset_TO; /// Timing offset used for compensating the time drift due to high speed
+  int              rx_offset_slot; /// Indicating time (in slots) after rx_offset calculation
+  int              rx_offset_comp; /// Already compensated rx_offset
 
   /// Timing Advance updates variables
   /// Timing advance update computed from the TA command signalled from gNB

openair1/SCHED_NR_UE/phy_procedures_nr_ue.c

@@ -916,7 +916,7 @@ void pbch_pdcch_processing(PHY_VARS_NR_UE *ue,
                                  dl_ch_estimates_time,
                                  frame_rx,
                                  nr_slot_rx,
-                                 0,
+                                 1,
                                  16384);
             }
             ue->apply_timing_offset = true;

radio/rfsimulator/simulator.c

@@ -947,11 +947,6 @@ static int rfsimulator_read(openair0_device *device, openair0_timestamp *ptimest
           sample_t *out=(sample_t *)samplesVoid[a];
           int nbAnt_tx = ptr->th.nbAnt;//number of Tx antennas
 
-          char filename[40];
-          sprintf(filename,"gNB_data.m");
-          char filename1[40];
-          sprintf(filename1,"gNB_Time.m");
-
           //LOG_I(HW, "nbAnt_tx %d\n",nbAnt_tx);
           for (int i=0; i < nsamps; i++) {//loop over nsamps
             for (int a_tx=0; a_tx<nbAnt_tx; a_tx++) { //sum up signals from nbAnt_tx antennas
@@ -966,27 +961,6 @@ static int rfsimulator_read(openair0_device *device, openair0_timestamp *ptimest
             out[i].r = (short)(outRealTmp * cos(2*M_PI*(double)SampIdxDoppler*fdopplerCurr/fsamp) - outImagTmp * sin(2*M_PI*(double)SampIdxDoppler*fdopplerCurr/fsamp));
             out[i].i = (short)(outImagTmp * cos(2*M_PI*(double)SampIdxDoppler*fdopplerCurr/fsamp) + outRealTmp * sin(2*M_PI*(double)SampIdxDoppler*fdopplerCurr/fsamp));
 
-            
-            if(t-> typeStamp == ENB_MAGICDL)
-            {
-              FILE *fptr;
-              FILE *fptr1;
-              double tTmp = SampIdxDoppler/fsamp;
-              
-              if ((i%1000==0) && (tTmp <= 10))
-              {
-                printf("*************** gNB Recording!, i: %d, fdopplerCurr: %d, tTmp: %f\n", i, fdopplerCurr, tTmp);
-                fptr = fopen(filename,"a");
-                fptr1 = fopen(filename1,"a");
-                fprintf(fptr,"%i\n",fdopplerCurr);
-                fprintf(fptr1,"%f\n",tTmp);
-                fclose(fptr);
-                fclose(fptr1);
-              }
-              
-            }
-            
-
             SampIdxDoppler++;
             CntDoppRate++;
             if ( CntDoppRate > NrSampFrame ) {