SRSUE: Added UL force amplitude optional parameter

lib/include/srslte/interfaces/ue_interfaces.h

@@ -734,6 +734,7 @@ typedef struct {
   uint32_t      intra_freq_meas_len_ms;
   uint32_t      intra_freq_meas_period_ms;
   bool          pregenerate_signals;
+  float         force_ul_amplitude;
 
   srslte::channel::args_t dl_channel_args;
   srslte::channel::args_t ul_channel_args;

lib/include/srslte/phy/ue/ue_ul.h

@@ -80,6 +80,7 @@ typedef struct SRSLTE_API {
   uint32_t        cc_idx;
 
   bool  normalize_en;
+  float force_peak_amplitude;
   bool  cfo_en;
   float cfo_tol;
   float cfo_value;

lib/src/phy/ue/ue_ul.c

@@ -248,9 +248,26 @@ static void apply_cfo(srslte_ue_ul_t* q, srslte_ue_ul_cfg_t* cfg)
 
 static void apply_norm(srslte_ue_ul_t* q, srslte_ue_ul_cfg_t* cfg, float norm_factor)
 {
+  uint32_t sf_len = SRSLTE_SF_LEN_PRB(q->cell.nof_prb);
+
   if (cfg->normalize_en) {
     norm_factor = limit_norm_factor(q, norm_factor, q->out_buffer);
-    srslte_vec_sc_prod_cfc(q->out_buffer, norm_factor, q->out_buffer, SRSLTE_SF_LEN_PRB(q->cell.nof_prb));
+    srslte_vec_sc_prod_cfc(q->out_buffer, norm_factor, q->out_buffer, sf_len);
+  } else if (cfg->force_peak_amplitude > 0.0f) {
+    // Typecast buffer
+    float* buf = (float*)q->out_buffer;
+
+    // Get index of maximum absolute sample
+    uint32_t idx = srslte_vec_max_abs_fi(buf, sf_len * 2);
+
+    // Get maximum value
+    float scale = fabsf(buf[idx]);
+
+    // Avoid zero division
+    if (scale != 0.0f && scale != INFINITY) {
+      // Apply maximum peak amplitude
+      srslte_vec_sc_prod_cfc(q->out_buffer, cfg->force_peak_amplitude / scale, q->out_buffer, sf_len);
+    }
   }
 }
 

srsue/src/main.cc

@@ -325,7 +325,11 @@ void parse_args(all_args_t* args, int argc, char* argv[])
 
     ("expert.pdsch_8bit_decoder",
        bpo::value<bool>(&args->phy.pdsch_8bit_decoder)->default_value(false),
-       "Use 8-bit for LLR representation and turbo decoder trellis computation (Experimental)");
+       "Use 8-bit for LLR representation and turbo decoder trellis computation (Experimental)")
+
+    ("expert.force_ul_amplitude",
+       bpo::value<float>(&args->phy.force_ul_amplitude)->default_value(0.0),
+       "Forces the peak amplitude in the PUCCH, PUSCH and SRS (set 0.0 to 1.0, set to 0 or negative for disabling)");
 
   // Positional options - config file location
   bpo::options_description position("Positional options");

srsue/src/phy/phy_common.cc

@@ -178,7 +178,12 @@ void phy_common::set_ue_ul_cfg(srslte_ue_ul_cfg_t* ue_ul_cfg)
   // Setup uplink configuration
   bzero(ue_ul_cfg, sizeof(srslte_ue_ul_cfg_t));
   ue_ul_cfg->cfo_en                              = true;
-  ue_ul_cfg->normalize_en                        = true;
+  if (args->force_ul_amplitude > 0.0f) {
+    ue_ul_cfg->force_peak_amplitude = args->force_ul_amplitude;
+    ue_ul_cfg->normalize_en         = false;
+  } else {
+    ue_ul_cfg->normalize_en = true;
+  }
   ue_ul_cfg->ul_cfg.pucch.ack_nack_feedback_mode = SRSLTE_PUCCH_ACK_NACK_FEEDBACK_MODE_NORMAL;
 }
 

srsue/ue.conf.example

@@ -285,6 +285,7 @@ enable = false
 #                        used in TM1. It is True by default.
 #
 # pdsch_8bit_decoder:    Use 8-bit for LLR representation and turbo decoder trellis computation (Experimental)
+# force_ul_amplitude:    Forces the peak amplitude in the PUCCH, PUSCH and SRS (set 0.0 to 1.0, set to 0 or negative for disabling)
 #
 #####################################################################
 [expert]
@@ -312,6 +313,7 @@ enable = false
 #metrics_csv_filename = /tmp/ue_metrics.csv
 #pdsch_csi_enabled  = true
 #pdsch_8bit_decoder = false
+#force_ul_amplitude = 0
 
 # CFO related values
 #cfo_is_doppler      = false