Take into account CRS from neigbhour cells when measuring interference (#1757)

* Take into account CRS from neigbhour cells when measuring interference

* fix std::isnormal compilation

* Fixed compilation of test

* Address comments

* Remove unused overrides

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

@@ -74,6 +74,8 @@ SRSLTE_API uint32_t srslte_refsignal_cs_v(uint32_t port_id, uint32_t ref_symbol_
 
 SRSLTE_API uint32_t srslte_refsignal_cs_nof_symbols(srslte_refsignal_t* q, srslte_dl_sf_cfg_t* sf, uint32_t port_id);
 
+SRSLTE_API uint32_t srslte_refsignal_cs_nof_pilots_x_slot(uint32_t nof_ports);
+
 SRSLTE_API uint32_t srslte_refsignal_cs_nof_re(srslte_refsignal_t* q, srslte_dl_sf_cfg_t* sf, uint32_t port_id);
 
 SRSLTE_API int srslte_refsignal_mbsfn_init(srslte_refsignal_t* q, uint32_t max_prb);

lib/src/phy/ch_estimation/refsignal_dl.c

@@ -227,6 +227,18 @@ inline uint32_t srslte_refsignal_cs_nof_symbols(srslte_refsignal_t* q, srslte_dl
   }
 }
 
+inline uint32_t srslte_refsignal_cs_nof_pilots_x_slot(uint32_t nof_ports)
+{
+  switch (nof_ports) {
+    case 2:
+      return 8;
+    case 4:
+      return 12;
+    default:
+      return 4;
+  }
+}
+
 inline uint32_t srslte_refsignal_cs_nof_re(srslte_refsignal_t* q, srslte_dl_sf_cfg_t* sf, uint32_t port_id)
 {
   uint32_t nof_re = srslte_refsignal_cs_nof_symbols(q, sf, port_id);

srsue/hdr/phy/phy_common.h

@@ -213,6 +213,30 @@ public:
     return rx_gain_offset;
   }
 
+  void neighbour_cells_reset(uint32_t cc_idx) { avg_rsrp_neigh[cc_idx] = NAN; }
+
+  void set_neighbour_cells(uint32_t cc_idx, const std::vector<rrc_interface_phy_lte::phy_meas_t>& meas)
+  {
+    // Add RSRP in the linear domain and average
+    float total_rsrp = 0;
+    for (auto& m : meas) {
+      total_rsrp += srslte_convert_dB_to_power(m.rsrp);
+    }
+    if (std::isnormal(total_rsrp)) {
+      if (std::isnormal(avg_rsrp_neigh[cc_idx])) {
+        avg_rsrp_neigh[cc_idx] = SRSLTE_VEC_EMA(total_rsrp, avg_rsrp_neigh[cc_idx], 0.9);
+      } else {
+        avg_rsrp_neigh[cc_idx] = total_rsrp;
+      }
+    }
+  }
+  void reset_neighbour_cells()
+  {
+    for (uint32_t i = 0; i < SRSLTE_MAX_CARRIERS; i++) {
+      avg_rsrp_neigh[i] = NAN;
+    }
+  }
+
 private:
   std::mutex meas_mutex;
 
@@ -227,6 +251,8 @@ private:
   float    rx_gain_offset                      = 0.0f;
   float    avg_snr_db_cqi[SRSLTE_MAX_CARRIERS] = {};
   float    avg_noise[SRSLTE_MAX_CARRIERS]      = {};
+  float    avg_rsrp_neigh[SRSLTE_MAX_CARRIERS] = {};
+
   uint32_t pcell_report_period                 = 0;
   uint32_t rssi_read_cnt                       = 0;
 

srsue/hdr/phy/scell/intra_measure.h

@@ -55,6 +55,14 @@ class intra_measure : public srslte::thread
    *                               +---------+
    */
 public:
+  // Interface for reporting new cell measurements
+  class meas_itf
+  {
+  public:
+    virtual void cell_meas_reset(uint32_t cc_idx)                                                           = 0;
+    virtual void new_cell_meas(uint32_t cc_idx, const std::vector<rrc_interface_phy_lte::phy_meas_t>& meas) = 0;
+  };
+
   /**
    * Constructor
    */
@@ -71,7 +79,7 @@ public:
    * @param rrc SRSUE PHY->RRC interface for supplying the RRC with the measurements
    * @param log_h Physical layer Logging filter pointer
    */
-  void init(phy_common* common, rrc_interface_phy_lte* rrc, srslte::log* log_h);
+  void init(uint32_t cc_idx, phy_common* common, meas_itf* new_cell_itf, srslte::log* log_h);
 
   /**
    * Stops the operation of this component
@@ -191,8 +199,9 @@ private:
   const static int INTRA_FREQ_MEAS_PRIO = DEFAULT_PRIORITY + 5;
 
   scell_recv             scell                     = {};
-  rrc_interface_phy_lte* rrc                       = nullptr;
+  meas_itf*              new_cell_itf              = nullptr;
   srslte::log*           log_h                     = nullptr;
+  uint32_t               cc_idx                    = 0;
   uint32_t               current_earfcn            = 0;
   uint32_t               current_sflen             = 0;
   srslte_cell_t          serving_cell              = {};

srsue/hdr/phy/sync.h

@@ -48,7 +48,11 @@ namespace srsue {
 
 typedef _Complex float cf_t;
 
-class sync : public srslte::thread, public rsrp_insync_itf, public search_callback, public scell::sync_callback
+class sync : public srslte::thread,
+             public rsrp_insync_itf,
+             public search_callback,
+             public scell::sync_callback,
+             public scell::intra_measure::meas_itf
 {
 public:
   sync() : thread("SYNC"), sf_buffer(sync_nof_rx_subframes), dummy_buffer(sync_nof_rx_subframes){};
@@ -115,6 +119,10 @@ public:
    */
   void set_rx_channel_offset(uint32_t ch, int32_t offset) override { radio_h->set_channel_rx_offset(ch, offset); }
 
+  // Interface from scell::intra_measure for providing neighbour cell measurements
+  void cell_meas_reset(uint32_t cc_idx) override;
+  void new_cell_meas(uint32_t cc_idx, const std::vector<rrc_interface_phy_lte::phy_meas_t>& meas) override;
+
 private:
   void reset();
   void radio_error();

srsue/src/phy/phy_common.cc

@@ -699,12 +699,24 @@ void phy_common::update_measurements(uint32_t
       }
     }
 
+    // Calculate SINR using CRS from neighbours if are detected
+    float sinr_db = chest_res.snr_db;
+    if (std::isnormal(avg_rsrp_neigh[cc_idx])) {
+      cur_noise /= pow(10, rx_gain_offset / 10);
+
+      // Normalize the measured power ot the fraction of CRS pilots per PRB. Assume all neighbours have the same
+      // number of ports and CP length
+      uint32_t nof_re_x_prb = SRSLTE_NRE * (SRSLTE_CP_NSYMB(cell.cp));
+      float    factor       = nof_re_x_prb / (srslte_refsignal_cs_nof_pilots_x_slot(cell.nof_ports));
+      sinr_db = avg_rsrp_dbm[cc_idx] - srslte_convert_power_to_dB(avg_rsrp_neigh[cc_idx] / factor + cur_noise);
+    }
+
     // Average snr in the log domain
-    if (std::isnormal(chest_res.snr_db)) {
+    if (std::isnormal(sinr_db)) {
       if (!std::isnormal(avg_snr_db_cqi[cc_idx])) {
-        avg_snr_db_cqi[cc_idx] = chest_res.snr_db;
+        avg_snr_db_cqi[cc_idx] = sinr_db;
       } else {
-        avg_snr_db_cqi[cc_idx] = SRSLTE_VEC_EMA(chest_res.snr_db, avg_snr_db_cqi[cc_idx], snr_ema_coeff);
+        avg_snr_db_cqi[cc_idx] = SRSLTE_VEC_EMA(sinr_db, avg_snr_db_cqi[cc_idx], snr_ema_coeff);
       }
     }
 
@@ -877,6 +889,8 @@ void phy_common::reset()
   ZERO_OBJECT(avg_rsrq_db);
   ZERO_OBJECT(scell_cfg);
 
+  reset_neighbour_cells();
+
   // Note: Using memset to reset these members is forbidden because they are real objects, not plain arrays.
   {
     std::lock_guard<std::mutex> lock(pending_dl_ack_mutex);

srsue/src/phy/scell/intra_measure.cc

@@ -45,10 +45,11 @@ intra_measure::~intra_measure()
   free(search_buffer);
 }
 
-void intra_measure::init(phy_common* common, rrc_interface_phy_lte* rrc_, srslte::log* log_h_)
+void intra_measure::init(uint32_t cc_idx_, phy_common* common, meas_itf* new_cell_itf_, srslte::log* log_h_)
 {
-  rrc   = rrc_;
+  cc_idx       = cc_idx_;
-  log_h = log_h_;
+  new_cell_itf = new_cell_itf_;
+  log_h        = log_h_;
 
   if (common) {
     intra_freq_meas_len_ms    = common->args->intra_freq_meas_len_ms;
@@ -174,6 +175,8 @@ void intra_measure::measure_proc()
   // Initialise empty neighbour cell list
   std::vector<rrc_interface_phy_lte::phy_meas_t> neighbour_cells = {};
 
+  new_cell_itf->cell_meas_reset(cc_idx);
+
   // Use Cell Reference signal to measure cells in the time domain for all known active PCI
   for (auto id : cells_to_measure) {
     // Do not measure serving cell here since it's measured by workers
@@ -208,7 +211,7 @@ void intra_measure::measure_proc()
 
   // Send measurements to RRC if any cell found
   if (not neighbour_cells.empty()) {
-    rrc->new_cell_meas(neighbour_cells);
+    new_cell_itf->new_cell_meas(cc_idx, neighbour_cells);
   }
 
   // Inform that measurement has finished

srsue/src/phy/sync.cc

@@ -100,7 +100,7 @@ void sync::init(srslte::radio_interface_phy* _radio,
   // Start intra-frequency measurement
   for (uint32_t i = 0; i < worker_com->args->nof_carriers; i++) {
     scell::intra_measure* q = new scell::intra_measure;
-    q->init(worker_com, stack, log_h);
+    q->init(i, worker_com, this, log_h);
     intra_freq_meas.push_back(std::unique_ptr<scell::intra_measure>(q));
   }
 
@@ -1027,4 +1027,18 @@ void sync::scell_sync_stop()
   }
 }
 
+void sync::cell_meas_reset(uint32_t cc_idx)
+{
+  worker_com->neighbour_cells_reset(cc_idx);
+}
+
+void sync::new_cell_meas(uint32_t cc_idx, const std::vector<rrc_interface_phy_lte::phy_meas_t>& meas)
+{
+  // Pass measurements to phy_common for SINR estimation
+  worker_com->set_neighbour_cells(cc_idx, meas);
+
+  // Pass-through to the stack
+  stack->new_cell_meas(meas);
+}
+
 } // namespace srsue

srsue/test/phy/scell_search_test.cc

@@ -227,7 +227,7 @@ public:
   }
 };
 
-class dummy_rrc : public srsue::rrc_interface_phy_lte
+class meas_itf_listener : public srsue::scell::intra_measure::meas_itf
 {
 public:
   typedef struct {
@@ -242,9 +242,8 @@ public:
 
   std::map<uint32_t, cell_meas_t> cells;
 
-  void in_sync() override {}
+  void cell_meas_reset(uint32_t cc_idx) override {}
-  void out_of_sync() override {}
+  void new_cell_meas(uint32_t cc_idx, const std::vector<srsue::rrc_interface_phy_lte::phy_meas_t>& meas) override
-  void new_cell_meas(const std::vector<phy_meas_t>& meas) override
   {
     for (auto& m : meas) {
       uint32_t pci = m.pci;
@@ -269,11 +268,6 @@ public:
     }
   }
 
-  void cell_search_complete(cell_search_ret_t ret, srsue::phy_cell_t found_cell) override {}
-  void cell_select_complete(bool status) override {}
-  void set_config_complete(bool status) override {}
-  void set_scell_complete(bool status) override {}
-
   bool print_stats()
   {
     printf("\n-- Statistics:\n");
@@ -418,7 +412,7 @@ int main(int argc, char** argv)
   srslte::rf_timestamp_t      ts              = {};
   srsue::scell::intra_measure intra_measure;
   srslte::log_filter          logger("intra_measure");
-  dummy_rrc                   rrc;
+  meas_itf_listener           rrc;
   srsue::phy_common           common;
 
   // Simulation only
@@ -489,7 +483,7 @@ int main(int argc, char** argv)
 
   logger.set_level(intra_meas_log_level);
 
-  intra_measure.init(&common, &rrc, &logger);
+  intra_measure.init(0, &common, &rrc, &logger);
   intra_measure.set_primary_cell(SRSLTE_MAX(earfcn_dl, 0), cell_base);
 
   if (earfcn_dl >= 0) {