Implementation of delay estimation in NFAPI_NR_DMRS_TYPE1_linear_interp() at UE

common/utils/nr/nr_common.h

@@ -72,6 +72,15 @@ typedef enum frequency_range_e {
   FR2
 } frequency_range_t;
 
+typedef struct {
+  /// Time shift in number of samples estimated based on DMRS-PDSCH/PUSCH
+  int est_delay;
+  /// Max position in OFDM symbol related to time shift estimation based on DMRS-PDSCH/PUSCH
+  int delay_max_pos;
+  /// Max value related to time shift estimation based on DMRS-PDSCH/PUSCH
+  int delay_max_val;
+} delay_t;
+
 extern const nr_bandentry_t nr_bandtable[];
 
 static inline int get_num_dmrs(uint16_t dmrs_mask ) {
@@ -114,6 +123,7 @@ uint32_t get_ssb_offset_to_pointA(uint32_t absoluteFrequencySSB,
                                   int ssbSubcarrierSpacing,
                                   int frequency_range);
 int get_ssb_subcarrier_offset(uint32_t absoluteFrequencySSB, uint32_t absoluteFrequencyPointA);
+
 #define CEILIDIV(a,b) ((a+b-1)/b)
 #define ROUNDIDIV(a,b) (((a<<1)+b)/(b<<1))
 

openair1/PHY/NR_ESTIMATION/nr_measurements_gNB.c

@@ -38,10 +38,10 @@
 
 extern openair0_config_t openair0_cfg[MAX_CARDS];
 
-void nr_est_timing_advance_pusch(const NR_DL_FRAME_PARMS *frame_parms, const int32_t *ul_ch_estimates_time, NR_ULSCH_delay_t *delay)
+void nr_est_timing_advance_pusch(const NR_DL_FRAME_PARMS *frame_parms, const int32_t *ul_ch_estimates_time, delay_t *delay)
 {
-  int max_pos = delay->pusch_delay_max_pos;
-  int max_val = delay->pusch_delay_max_val;
+  int max_pos = delay->delay_max_pos;
+  int max_val = delay->delay_max_val;
   const int sync_pos = 0;
 
   for (int i = 0; i < frame_parms->ofdm_symbol_size; i++) {
@@ -56,9 +56,9 @@ void nr_est_timing_advance_pusch(const NR_DL_FRAME_PARMS *frame_parms, const int
   if (max_pos > frame_parms->ofdm_symbol_size / 2)
     max_pos = max_pos - frame_parms->ofdm_symbol_size;
 
-  delay->pusch_delay_max_pos = max_pos;
-  delay->pusch_delay_max_val = max_val;
-  delay->pusch_est_delay = max_pos - sync_pos;
+  delay->delay_max_pos = max_pos;
+  delay->delay_max_val = max_val;
+  delay->est_delay = max_pos - sync_pos;
 }
 
 int nr_est_timing_advance_srs(const NR_DL_FRAME_PARMS *frame_parms, 

openair1/PHY/NR_ESTIMATION/nr_ul_channel_estimation.c

@@ -42,9 +42,10 @@
 #define NO_INTERP 1
 #define dBc(x,y) (dB_fixed(((int32_t)(x))*(x) + ((int32_t)(y))*(y)))
 
-void freq2time(uint16_t ofdm_symbol_size,
-               int16_t *freq_signal,
-               int16_t *time_signal) {
+static void freq2time(uint16_t ofdm_symbol_size,
+                      int16_t *freq_signal,
+                      int16_t *time_signal)
+{
 
   switch (ofdm_symbol_size) {
     case 128:
@@ -194,7 +195,7 @@ int nr_pusch_channel_estimation(PHY_VARS_gNB *gNB,
   uint64_t noise_amp2 = 0;
   c16_t ul_ls_est[symbolSize] __attribute__((aligned(32)));
   memset(ul_ls_est, 0, sizeof(c16_t) * symbolSize);
-  NR_ULSCH_delay_t *delay = &gNB->ulsch[ul_id].delay;
+  delay_t *delay = &gNB->ulsch[ul_id].delay;
   memset(delay, 0, sizeof(*delay));
 
   for (int aarx=0; aarx<gNB->frame_parms.nb_antennas_rx; aarx++) {
@@ -239,7 +240,7 @@ int nr_pusch_channel_estimation(PHY_VARS_gNB *gNB,
       freq2time(symbolSize, (int16_t *)ul_ls_est, (int16_t *)pusch_vars->ul_ch_estimates_time[aarx]);
 
       nr_est_timing_advance_pusch(&gNB->frame_parms, pusch_vars->ul_ch_estimates_time[aarx], delay);
-      int pusch_delay = delay->pusch_est_delay;
+      int pusch_delay = delay->est_delay;
       int delay_idx = get_delay_idx(pusch_delay);
       c16_t *ul_delay_table = gNB->frame_parms.ul_delay_table[delay_idx];
 
@@ -325,7 +326,7 @@ int nr_pusch_channel_estimation(PHY_VARS_gNB *gNB,
       // Delay compensation
       freq2time(symbolSize, (int16_t *)ul_ls_est, (int16_t *)pusch_vars->ul_ch_estimates_time[aarx]);
       nr_est_timing_advance_pusch(&gNB->frame_parms, pusch_vars->ul_ch_estimates_time[aarx], delay);
-      int pusch_delay = delay->pusch_est_delay;
+      int pusch_delay = delay->est_delay;
       int delay_idx = get_delay_idx(-pusch_delay);
       c16_t *ul_delay_table = gNB->frame_parms.ul_delay_table[delay_idx];
       for (int n = 0; n < nb_rb_pusch * NR_NB_SC_PER_RB; n++) {

openair1/PHY/NR_ESTIMATION/nr_ul_estimation.h

@@ -61,8 +61,7 @@ void nr_gnb_measurements(PHY_VARS_gNB *gNB,
                          uint8_t nrOfLayers);
 
 void nr_est_timing_advance_pusch(const NR_DL_FRAME_PARMS *frame_parms,
-                                 const int32_t *ul_ch_estimates_time,
-                                 NR_ULSCH_delay_t *delay);
+                                 const int32_t *ul_ch_estimates_time, delay_t *delay);
 
 int nr_est_timing_advance_srs(const NR_DL_FRAME_PARMS *frame_parms,
                               const int32_t srs_estimated_channel_time[][frame_parms->ofdm_symbol_size]);

openair1/PHY/NR_UE_ESTIMATION/nr_dl_channel_estimation.c

@@ -1303,112 +1303,127 @@ void nr_pdcch_channel_estimation(PHY_VARS_NR_UE *ue,
   }
 }
 
+static void freq2time(uint16_t ofdm_symbol_size,
+                      int16_t *freq_signal,
+                      int16_t *time_signal)
+{
+
+  switch (ofdm_symbol_size) {
+    case 128:
+      idft(IDFT_128, freq_signal, time_signal, 1);
+      break;
+    case 256:
+      idft(IDFT_256, freq_signal, time_signal, 1);
+      break;
+    case 512:
+      idft(IDFT_512, freq_signal, time_signal, 1);
+      break;
+    case 1024:
+      idft(IDFT_1024, freq_signal, time_signal, 1);
+      break;
+    case 1536:
+      idft(IDFT_1536, freq_signal, time_signal, 1);
+      break;
+    case 2048:
+      idft(IDFT_2048, freq_signal, time_signal, 1);
+      break;
+    case 4096:
+      idft(IDFT_4096, freq_signal, time_signal, 1);
+      break;
+    case 6144:
+      idft(IDFT_6144, freq_signal, time_signal, 1);
+      break;
+    case 8192:
+      idft(IDFT_8192, freq_signal, time_signal, 1);
+      break;
+    default:
+      AssertFatal (1 == 0, "Invalid ofdm_symbol_size %i\n", ofdm_symbol_size);
+      break;
+  }
+}
+
+void nr_est_delay_pdsch(const NR_DL_FRAME_PARMS *frame_parms, const c16_t *dl_ls_est, delay_t *delay)
+{
+  c16_t dl_ch_estimates_time[frame_parms->ofdm_symbol_size] __attribute__((aligned(32)));
+  memset(dl_ch_estimates_time, 0, sizeof(dl_ch_estimates_time));
+  freq2time(frame_parms->ofdm_symbol_size, (int16_t *)dl_ls_est, (int16_t *)dl_ch_estimates_time);
+
+  int max_pos = delay->delay_max_pos;
+  int max_val = delay->delay_max_val;
+  const int sync_pos = 0;
+
+  for (int i = 0; i < frame_parms->ofdm_symbol_size; i++) {
+    int temp = c16amp2(dl_ch_estimates_time[i]) >> 1;
+    if (temp > max_val) {
+      max_pos = i;
+      max_val = temp;
+    }
+  }
+
+  if (max_pos > frame_parms->ofdm_symbol_size / 2)
+    max_pos = max_pos - frame_parms->ofdm_symbol_size;
+
+  delay->delay_max_pos = max_pos;
+  delay->delay_max_val = max_val;
+  delay->est_delay = max_pos - sync_pos;
+}
+
 void NFAPI_NR_DMRS_TYPE1_linear_interp(NR_DL_FRAME_PARMS *frame_parms,
                                        c16_t *rxF,
                                        c16_t *pil,
                                        c16_t *dl_ch,
                                        unsigned short bwp_start_subcarrier,
                                        unsigned short nb_rb_pdsch,
-                                       int8_t delta)
+                                       int8_t delta,
+                                       delay_t *delay)
 {
   int re_offset = bwp_start_subcarrier % frame_parms->ofdm_symbol_size;
-  c16_t *pil0 = pil;
-  c16_t *dl_ch0 = dl_ch;
-  c16_t ch = {0};
-
-  const int16_t *fdcl = NULL;
-  const int16_t *fdcr = NULL;
-  const int16_t *fdclh = NULL;
-  const int16_t *fdcrh = NULL;
-  switch (delta) {
-    case 0: // port 0,1
-      fdcl = filt8_dcl0; // left DC interpolation Filter (even RB)
-      fdcr = filt8_dcr0; // right DC interpolation Filter (even RB)
-      fdclh = filt8_dcl0_h; // left DC interpolation Filter (odd RB)
-      fdcrh = filt8_dcr0_h; // right DC interpolation Filter (odd RB)
-      break;
 
-    case 1: // port2,3
-      fdcl = filt8_dcl1;
-      fdcr = filt8_dcr1;
-      fdclh = filt8_dcl1_h;
-      fdcrh = filt8_dcr1_h;
-      break;
-
-    default:
-      AssertFatal(1 == 0, "pdsch_channel_estimation: Invalid delta %i\n", delta);
-      break;
-  }
+  c16_t dl_ls_est[frame_parms->ofdm_symbol_size] __attribute__((aligned(32)));
+  memset(dl_ls_est, 0, sizeof(dl_ls_est));
 
   for (int pilot_cnt = 0; pilot_cnt < 6 * nb_rb_pdsch; pilot_cnt++) {
     if (pilot_cnt % 2 == 0) {
-      ch = c16mulShift(*pil, rxF[re_offset], 15);
+      c16_t ch = c16mulShift(*pil, rxF[re_offset], 15);
       pil++;
       re_offset = (re_offset + 2) % frame_parms->ofdm_symbol_size;
       ch = c16maddShift(*pil, rxF[re_offset], ch, 15);
       ch = c16Shift(ch, 1);
       pil++;
       re_offset = (re_offset + 2) % frame_parms->ofdm_symbol_size;
+      for (int k = pilot_cnt << 1; k < (pilot_cnt << 1) + 4; k++) {
+        dl_ls_est[k] = ch;
+      }
     }
 
 #ifdef DEBUG_PDSCH
-    printf("pilot %3d: pil -> (%6d,%6d), rxF -> (%4d,%4d), ch -> (%4d,%4d) \n", pilot_cnt, pil->r, pil->i, rxF[re_offset].r, rxF[re_offset].i, ch.r, ch.i);
+    printf("pilot %3d: pil -> (%6d,%6d), rxF -> (%4d,%4d), ch -> (%4d,%4d) \n",
+           pilot_cnt,
+           pil->r,
+           pil->i,
+           rxF[re_offset].r,
+           rxF[re_offset].i,
+           dl_ls_est[pilot_cnt << 1].r,
+           dl_ls_est[pilot_cnt << 1].i);
 #endif
+  }
+
+  nr_est_delay_pdsch(frame_parms, dl_ls_est, delay);
 
+  for (int pilot_cnt = 0; pilot_cnt < 6 * nb_rb_pdsch; pilot_cnt++) {
     if (pilot_cnt == 0) { // Treat first pilot
-      c16multaddVectRealComplex(filt16_ul_p0, &ch, dl_ch, 16);
+      c16multaddVectRealComplex(filt16_ul_p0, &dl_ls_est[pilot_cnt << 1], dl_ch, 16);
     } else if (pilot_cnt == 1 || pilot_cnt == 2) {
-      c16multaddVectRealComplex(filt16_ul_p1p2, &ch, dl_ch, 16);
+      c16multaddVectRealComplex(filt16_ul_p1p2, &dl_ls_est[pilot_cnt << 1], dl_ch, 16);
     } else if (pilot_cnt == 6 * nb_rb_pdsch - 1) { // Treat last pilot
-      c16multaddVectRealComplex(filt16_ul_last, &ch, dl_ch, 16);
+      c16multaddVectRealComplex(filt16_ul_last, &dl_ls_est[pilot_cnt << 1], dl_ch, 16);
     } else { // Treat middle pilots
-      c16multaddVectRealComplex(filt16_ul_middle, &ch, dl_ch, 16);
+      c16multaddVectRealComplex(filt16_ul_middle, &dl_ls_est[pilot_cnt << 1], dl_ch, 16);
       if (pilot_cnt % 2 == 0) {
         dl_ch += 4;
       }
     }
   }
-
-  // check if PRB crosses DC and improve estimates around DC
-  if ((bwp_start_subcarrier < frame_parms->ofdm_symbol_size) && (bwp_start_subcarrier + nb_rb_pdsch * 12 >= frame_parms->ofdm_symbol_size)) {
-    dl_ch = dl_ch0;
-    uint16_t idxDC = 2 * (frame_parms->ofdm_symbol_size - bwp_start_subcarrier);
-    uint16_t idxPil = idxDC / 4;
-    re_offset = bwp_start_subcarrier % frame_parms->ofdm_symbol_size;
-    pil = pil0;
-    pil += (idxPil - 1);
-    dl_ch += (idxDC / 2 - 2);
-    dl_ch = memset(dl_ch, 0, sizeof(c16_t) * 5);
-    re_offset = (re_offset + idxDC / 2 - 2) % frame_parms->ofdm_symbol_size;
-    ch = c16mulShift(*pil, rxF[re_offset], 15);
-    pil++;
-    re_offset = (re_offset + 2) % frame_parms->ofdm_symbol_size;
-    ch = c16maddShift(*pil, rxF[re_offset], ch, 15);
-    ch = c16Shift(ch, 1);
-
-    // for proper allignment of SIMD vectors
-    if ((frame_parms->N_RB_DL & 1) == 0) {
-      c16multaddVectRealComplex(fdcl, &ch, dl_ch - 2, 8);
-      pil++;
-      re_offset = (re_offset + 2) % frame_parms->ofdm_symbol_size;
-      ch = c16mulShift(*pil, rxF[re_offset], 15);
-      pil++;
-      re_offset = (re_offset + 2) % frame_parms->ofdm_symbol_size;
-      ch = c16maddShift(*pil, rxF[re_offset], ch, 15);
-      ch = c16Shift(ch, 1);
-      c16multaddVectRealComplex(fdcr, &ch, dl_ch - 2, 8);
-    } else {
-      c16multaddVectRealComplex(fdclh, &ch, dl_ch, 8);
-      pil++;
-      re_offset = (re_offset + 2) % frame_parms->ofdm_symbol_size;
-      ch = c16mulShift(*pil, rxF[re_offset], 15);
-      pil++;
-      re_offset = (re_offset + 2) % frame_parms->ofdm_symbol_size;
-      ch = c16maddShift(*pil, rxF[re_offset], ch, 15);
-      ch = c16Shift(ch, 1);
-      c16multaddVectRealComplex(fdcrh, &ch, dl_ch, 8);
-    }
-  }
 }
 
 void NFAPI_NR_DMRS_TYPE1_average_prb(NR_DL_FRAME_PARMS *frame_parms,
@@ -1503,7 +1518,8 @@ void NFAPI_NR_DMRS_TYPE2_linear_interp(NR_DL_FRAME_PARMS *frame_parms,
                                        unsigned short bwp_start_subcarrier,
                                        unsigned short nb_rb_pdsch,
                                        int8_t delta,
-                                       unsigned short p)
+                                       unsigned short p,
+                                       delay_t *delay)
 {
   int re_offset = bwp_start_subcarrier % frame_parms->ofdm_symbol_size;
   c16_t *dl_ch0 = dl_ch;
@@ -1715,6 +1731,8 @@ int nr_pdsch_channel_estimation(PHY_VARS_NR_UE *ue,
       ue->frame_parms.nushift = nushift;
   }
 
+  delay_t delay = {0};
+
   for (int aarx = 0; aarx < ue->frame_parms.nb_antennas_rx; aarx++) {
 
 #ifdef DEBUG_PDSCH
@@ -1734,7 +1752,8 @@ int nr_pdsch_channel_estimation(PHY_VARS_NR_UE *ue,
                                         dl_ch,
                                         bwp_start_subcarrier,
                                         nb_rb_pdsch,
-                                        delta);
+                                        delta,
+                                        &delay);
 
     } else if (config_type == NFAPI_NR_DMRS_TYPE2 && ue->chest_freq == 0) {
       NFAPI_NR_DMRS_TYPE2_linear_interp(&ue->frame_parms,

openair1/PHY/defs_gNB.h

@@ -255,15 +255,6 @@ typedef struct {
   int subband_cqi_tot_dB[275];
 } ulsch_measurements_gNB;
 
-typedef struct {
-  /// Time shift in number of samples estimated based on DMRS-PUSCH
-  int pusch_est_delay;
-  /// Max position in OFDM symbol related to time shift estimation based on DMRS-PUSCH
-  int pusch_delay_max_pos;
-  /// Max value related to time shift estimation based on DMRS-PUSCH
-  int pusch_delay_max_val;
-} NR_ULSCH_delay_t;
-
 typedef struct {
   uint32_t frame;
   uint32_t slot;
@@ -281,7 +272,7 @@ typedef struct {
   bool active;
   /// Flag to indicate that the UL configuration has been handled. Used to remove a stale ULSCH when frame wraps around
   uint8_t handled;
-  NR_ULSCH_delay_t delay;
+  delay_t delay;
   ulsch_measurements_gNB ulsch_measurements;
 } NR_gNB_ULSCH_t;
 

openair1/SCHED_NR/phy_procedures_nr_gNB.c

@@ -422,7 +422,7 @@ void nr_fill_indication(PHY_VARS_gNB *gNB, int frame, int slot_rx, int ULSCH_id,
   nfapi_nr_pusch_pdu_t *pusch_pdu = &harq_process->ulsch_pdu;
 
   // Get estimated timing advance for MAC
-  int sync_pos = ulsch->delay.pusch_est_delay;
+  int sync_pos = ulsch->delay.est_delay;
 
   // scale the 16 factor in N_TA calculation in 38.213 section 4.2 according to the used FFT size
   uint16_t bw_scaling = 16 * gNB->frame_parms.ofdm_symbol_size / 2048;

openair1/SIMULATION/NR_PHY/ulsim.c

@@ -1540,9 +1540,9 @@ int main(int argc, char **argv)
       if (!crc_status)
         effRate += ((double)TBS) / (double)round;
 
-      sum_pusch_delay += ulsch_gNB->delay.pusch_est_delay;
-      min_pusch_delay = ulsch_gNB->delay.pusch_est_delay < min_pusch_delay ? ulsch_gNB->delay.pusch_est_delay : min_pusch_delay;
-      max_pusch_delay = ulsch_gNB->delay.pusch_est_delay > max_pusch_delay ? ulsch_gNB->delay.pusch_est_delay : max_pusch_delay;
+      sum_pusch_delay += ulsch_gNB->delay.est_delay;
+      min_pusch_delay = min(ulsch_gNB->delay.est_delay, min_pusch_delay);
+      max_pusch_delay = max(ulsch_gNB->delay.est_delay, max_pusch_delay);
       delay_pusch_est_count++;
 
     } // trial loop