Added UE synchronization error metric (hard-coded disabled by default)

lib/include/srslte/phy/ch_estimation/chest_dl.h

@@ -63,6 +63,7 @@ typedef struct SRSLTE_API {
   float    rsrq_ant_port_db[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS];
   float    rssi_dbm;
   float    cfo;
+  float    sync_error;
 } srslte_chest_dl_res_t;
 
 typedef enum SRSLTE_API {
@@ -98,6 +99,7 @@ typedef struct SRSLTE_API {
   float rsrp[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS];
   float rsrp_corr[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS];
   float noise_estimate[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS];
+  float sync_err[SRSLTE_MAX_PORTS][SRSLTE_MAX_PORTS];
   float cfo;
 
   /* Use PSS for noise estimation in LS linear interpolation mode */
@@ -118,6 +120,7 @@ typedef struct SRSLTE_API {
   bool     rsrp_neighbour;
   bool     cfo_estimate_enable;
   uint32_t cfo_estimate_sf_mask;
+  bool     sync_error_enable;
 
 } srslte_chest_dl_cfg_t;
 

lib/src/phy/ch_estimation/chest_dl.c

@@ -691,6 +691,19 @@ static int estimate_port(srslte_chest_dl_t*     q,
   srslte_vec_prod_conj_ccc(
       q->pilot_recv_signal, q->csr_refs.pilots[port_id / 2][sf->tti % 10], q->pilot_estimates, npilots);
 
+  // Estimate synchronization error
+  if (cfg->sync_error_enable) {
+    uint32_t nsymb = srslte_refsignal_cs_nof_symbols(&q->csr_refs, sf, port_id);
+    float    k     = (float)srslte_symbol_sz(q->cell.nof_prb) / 6.0f;
+    float    sum   = 0.0f;
+    for (uint32_t i = 0; i < nsymb; i++) {
+      sum += srslte_vec_estimate_frequency(q->pilot_estimates + i * npilots / nsymb, npilots / nsymb) * k;
+    }
+    q->sync_err[rxant_id][port_id] = sum / nsymb;
+  } else {
+    q->sync_err[rxant_id][port_id] = NAN;
+  }
+
   /* Compute RSRP for the channel estimates in this port */
   if (cfg->rsrp_neighbour) {
     double energy = cabs(srslte_vec_acc_cc(q->pilot_estimates, npilots)/npilots);
@@ -843,6 +856,7 @@ static void fill_res(srslte_chest_dl_t* q, srslte_chest_dl_res_t* res)
   res->rsrq_db            = db(res->rsrq);
   res->snr_db             = db(get_snr(q));
   res->rssi_dbm           = dbm(get_rssi(q));
+  res->sync_error         = q->sync_err[0][0]; // Take only the channel used for synch
 
   for (uint32_t port_id = 0; port_id < q->cell.nof_ports; port_id++) {
     res->rsrp_port_dbm[port_id] = dbm(get_rsrp_port(q, port_id));

srsue/hdr/phy/phy_metrics.h

@@ -44,6 +44,7 @@ struct dl_metrics_t
   float turbo_iters;
   float mcs;
   float pathloss;
+  float sync_err;
 };
 
 struct ul_metrics_t

srsue/hdr/phy/sf_worker.h

@@ -61,6 +61,7 @@ public:
   void set_crnti(uint16_t rnti);
   void enable_pregen_signals(bool enabled);
 
+  /* Methods for plotting */
   int      read_ce_abs(float* ce_abs, uint32_t tx_antenna, uint32_t rx_antenna);
   uint32_t get_cell_nof_ports()
   {
@@ -72,6 +73,8 @@ public:
   }
   uint32_t get_rx_nof_antennas() { return phy->args->nof_rx_ant; }
   int      read_pdsch_d(cf_t* pdsch_d);
+  float    get_sync_error();
+  float    get_cfo();
   void     start_plot();
 
 private:

srsue/src/phy/cc_worker.cc

@@ -652,6 +652,7 @@ void cc_worker::update_measurements()
   dl_metrics.rssi     = phy->avg_rssi_dbm;
   dl_metrics.pathloss = phy->pathloss[cc_idx];
   dl_metrics.sinr     = phy->avg_snr_db_cqi[cc_idx];
+  dl_metrics.sync_err = ue_dl.chest_res.sync_error;
 
   phy->set_dl_metrics(dl_metrics, cc_idx);
   phy->set_ul_metrics(ul_metrics, cc_idx);

srsue/src/phy/phy_common.cc

@@ -154,6 +154,7 @@ void phy_common::set_ue_dl_cfg(srslte_ue_dl_cfg_t* ue_dl_cfg)
   }
 
   chest_cfg->rsrp_neighbour       = false;
+  chest_cfg->sync_error_enable    = false;
   chest_cfg->interpolate_subframe = args->interpolate_subframe_enabled;
   chest_cfg->cfo_estimate_enable  = args->cfo_ref_mask != 0;
   chest_cfg->cfo_estimate_sf_mask = args->cfo_ref_mask;
@@ -610,6 +611,8 @@ void phy_common::set_dl_metrics(const dl_metrics_t m, uint32_t cc_idx)
   dl_metrics[cc_idx].rssi = dl_metrics[cc_idx].rssi + (m.rssi - dl_metrics[cc_idx].rssi) / dl_metrics_count;
   dl_metrics[cc_idx].rsrp = dl_metrics[cc_idx].rsrp + (m.rsrp - dl_metrics[cc_idx].rsrp) / dl_metrics_count;
   dl_metrics[cc_idx].sinr = dl_metrics[cc_idx].sinr + (m.sinr - dl_metrics[cc_idx].sinr) / dl_metrics_count;
+  dl_metrics[cc_idx].sync_err =
+      dl_metrics[cc_idx].sync_err + (m.sync_err - dl_metrics[cc_idx].sync_err) / dl_metrics_count;
   dl_metrics[cc_idx].pathloss =
       dl_metrics[cc_idx].pathloss + (m.pathloss - dl_metrics[cc_idx].pathloss) / dl_metrics_count;
   dl_metrics[cc_idx].turbo_iters =

srsue/src/phy/sf_worker.cc

@@ -395,7 +395,19 @@ int sf_worker::read_pdsch_d(cf_t* pdsch_d)
 {
   return cc_workers[0]->read_pdsch_d(pdsch_d);
 }
+float sf_worker::get_sync_error()
+{
+  dl_metrics_t dl_metrics[SRSLTE_MAX_CARRIERS] = {};
+  phy->get_dl_metrics(dl_metrics);
+  return dl_metrics->sync_err;
+}
 
+float sf_worker::get_cfo()
+{
+  sync_metrics_t sync_metrics = {};
+  phy->get_sync_metrics(sync_metrics);
+  return sync_metrics.cfo;
+}
 } // namespace srsue
 
 /***********************************************************
@@ -419,9 +431,17 @@ static uint32_t    icfo = 0;
 static float       cfo_buffer[CFO_PLOT_LEN];
 #endif /* CFO_PLOT_LEN > 0 */
 
+#define SYNC_PLOT_LEN 0 /* Set to non zero for enabling Sync error plot */
+#if SYNC_PLOT_LEN > 0
+static plot_real_t psync;
+static uint32_t    isync = 0;
+static float       sync_buffer[SYNC_PLOT_LEN];
+#endif /* SYNC_PLOT_LEN > 0 */
+
 void* plot_thread_run(void* arg)
 {
   srsue::sf_worker* worker = (srsue::sf_worker*)arg;
+  uint32_t          row_count = 0;
 
   sdrgui_init();
   for (uint32_t tx = 0; tx < worker->get_cell_nof_ports(); tx++) {
@@ -436,13 +456,14 @@ void* plot_thread_run(void* arg)
       plot_real_addToWindowGrid(&pce[tx][rx], (char*)"srsue", tx, rx);
     }
   }
+  row_count = worker->get_rx_nof_antennas();
 
   plot_scatter_init(&pconst);
   plot_scatter_setTitle(&pconst, (char*)"PDSCH - Equalized Symbols");
   plot_scatter_setXAxisScale(&pconst, -4, 4);
   plot_scatter_setYAxisScale(&pconst, -4, 4);
 
-  plot_scatter_addToWindowGrid(&pconst, (char*)"srsue", 0, worker->get_rx_nof_antennas());
+  plot_scatter_addToWindowGrid(&pconst, (char*)"srsue", 0, row_count);
 
 #if CFO_PLOT_LEN > 0
   plot_real_init(&pcfo);
@@ -450,9 +471,18 @@ void* plot_thread_run(void* arg)
   plot_real_setLabels(&pcfo, (char*)"Time", (char*)"Hz");
   plot_real_setYAxisScale(&pcfo, -4000, 4000);
 
-  plot_scatter_addToWindowGrid(&pcfo, (char*)"srsue", 1, worker->get_rx_nof_antennas());
+  plot_scatter_addToWindowGrid(&pcfo, (char*)"srsue", 1, row_count++);
 #endif /* CFO_PLOT_LEN > 0 */
 
+#if SYNC_PLOT_LEN > 0
+  plot_real_init(&psync);
+  plot_real_setTitle(&psync, (char*)"Sync error (in samples)");
+  plot_real_setLabels(&psync, (char*)"Time", (char*)"Error");
+  plot_real_setYAxisScale(&psync, -2, +2);
+
+  plot_scatter_addToWindowGrid(&psync, (char*)"srsue", 1, row_count++);
+#endif /* SYNC_PLOT_LEN > 0 */
+
   int n;
   int readed_pdsch_re = 0;
   while (1) {