Channel emulator takes SNR as input parameter

lib/include/srslte/phy/channel/channel.h

@@ -41,7 +41,8 @@ public:
 
     // AWGN options
     bool  awgn_enable            = false;
-    float awgn_n0_dBfs = -30.0f;
+    float awgn_signal_power_dBfs = 0.0f;
+    float awgn_snr_dB            = 30.0f;
 
     // Fading options
     bool        fading_enable = false;
@@ -70,6 +71,7 @@ public:
   ~channel();
   void set_logger(log_filter* _log_h);
   void set_srate(uint32_t srate);
+  void set_signal_power_dBfs(float power_dBfs);
   void run(cf_t* in[SRSLTE_MAX_CHANNELS], cf_t* out[SRSLTE_MAX_CHANNELS], uint32_t len, const srslte_timestamp_t& t);
 
 private:

lib/include/srslte/phy/enb/enb_dl.h

@@ -160,4 +160,11 @@ SRSLTE_API void srslte_enb_dl_get_ack(const srslte_cell_t*      cell,
                                       const srslte_uci_value_t* uci_value,
                                       srslte_pdsch_ack_t*       pdsch_ack);
 
+/**
+ * Gets the maximum signal power in decibels full scale. It is equivalent to the transmit power if all resource elements
+ * were populated.
+ * @return The maximum power
+ */
+SRSLTE_API float srslte_enb_dl_get_maximum_signal_power_dBfs(uint32_t nof_prb);
+
 #endif // SRSLTE_ENB_DL_H

lib/src/phy/channel/channel.cc

@@ -78,7 +78,7 @@ channel::channel(const channel::args_t& channel_args, uint32_t _nof_channels)
   if (channel_args.awgn_enable && ret == SRSLTE_SUCCESS) {
     awgn = (srslte_channel_awgn_t*)calloc(sizeof(srslte_channel_awgn_t), 1);
     ret  = srslte_channel_awgn_init(awgn, 1234);
-    srslte_channel_awgn_set_n0(awgn, args.awgn_n0_dBfs);
+    srslte_channel_awgn_set_n0(awgn, args.awgn_signal_power_dBfs - args.awgn_snr_dB);
   }
 
   // Create high speed train
@@ -264,3 +264,10 @@ void channel::set_srate(uint32_t srate)
     current_srate = srate;
   }
 }
+
+void channel::set_signal_power_dBfs(float power_dBfs)
+{
+  if (awgn != nullptr) {
+    srslte_channel_awgn_set_n0(awgn, power_dBfs - args.awgn_snr_dB);
+  }
+}

lib/src/phy/enb/enb_dl.c

@@ -27,12 +27,12 @@
 #include <string.h>
 
 #define CURRENT_FFTSIZE srslte_symbol_sz(q->cell.nof_prb)
-#define CURRENT_SFLEN SRSLTE_SF_LEN(CURRENT_FFTSIZE)
-
-#define CURRENT_SLOTLEN_RE SRSLTE_SLOT_LEN_RE(q->cell.nof_prb, q->cell.cp)
 #define CURRENT_SFLEN_RE SRSLTE_NOF_RE(q->cell)
 
-#define SRSLTE_ENB_RF_AMP 0.1
+static float enb_dl_get_norm_factor(uint32_t nof_prb)
+{
+  return 0.05f / sqrtf(nof_prb);
+}
 
 int srslte_enb_dl_init(srslte_enb_dl_t* q, cf_t* out_buffer[SRSLTE_MAX_PORTS], uint32_t max_prb)
 {
@@ -408,7 +408,7 @@ int srslte_enb_dl_put_pmch(srslte_enb_dl_t* q, srslte_pmch_cfg_t* pmch_cfg, uint
 void srslte_enb_dl_gen_signal(srslte_enb_dl_t* q)
 {
   // TODO: PAPR control
-  float norm_factor = 0.05f / sqrtf(q->cell.nof_prb);
+  float norm_factor = enb_dl_get_norm_factor(q->cell.nof_prb);
 
   if (q->dl_sf.sf_type == SRSLTE_SF_MBSFN) {
     srslte_ofdm_tx_sf(&q->ifft_mbsfn);
@@ -642,3 +642,9 @@ void srslte_enb_dl_get_ack(const srslte_cell_t*      cell,
     ERROR("Not implemented for TDD\n");
   }
 }
+
+float srslte_enb_dl_get_maximum_signal_power_dBfs(uint32_t nof_prb)
+{
+  return srslte_convert_amplitude_to_dB(enb_dl_get_norm_factor(nof_prb)) +
+         srslte_convert_power_to_dB((float)nof_prb * SRSLTE_NRE) + 3.0f;
+}

srsenb/src/main.cc

@@ -143,7 +143,7 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     /* Downlink Channel emulator section */
     ("channel.dl.enable",            bpo::value<bool>(&args->phy.dl_channel_args.enable)->default_value(false),               "Enable/Disable internal Downlink channel emulator")
     ("channel.dl.awgn.enable",       bpo::value<bool>(&args->phy.dl_channel_args.awgn_enable)->default_value(false),          "Enable/Disable AWGN simulator")
-    ("channel.dl.awgn.n0", bpo::value<float>(&args->phy.dl_channel_args.awgn_n0_dBfs)->default_value(-30.0f), "Noise level in decibels full scale (dBfs)")
+    ("channel.dl.awgn.snr",          bpo::value<float>(&args->phy.dl_channel_args.awgn_snr_dB)->default_value(30.0f),         "Noise level in decibels full scale (dBfs)")
     ("channel.dl.fading.enable",     bpo::value<bool>(&args->phy.dl_channel_args.fading_enable)->default_value(false),        "Enable/Disable Fading model")
     ("channel.dl.fading.model",      bpo::value<std::string>(&args->phy.dl_channel_args.fading_model)->default_value("none"), "Fading model + maximum doppler (E.g. none, epa5, eva70, etu300, etc)")
     ("channel.dl.delay.enable",      bpo::value<bool>(&args->phy.dl_channel_args.delay_enable)->default_value(false),         "Enable/Disable Delay simulator")
@@ -160,9 +160,10 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     ("channel.dl.hst.init_time_s",   bpo::value<float>(&args->phy.dl_channel_args.hst_init_time_s)->default_value(0),         "Initial time in seconds")
 
     /* Uplink Channel emulator section */
-    ("channel.ul.enable", bpo::value<bool>(&args->phy.ul_channel_args.enable)->default_value(false), "Enable/Disable internal Uplink channel emulator")
+    ("channel.ul.enable",            bpo::value<bool>(&args->phy.ul_channel_args.enable)->default_value(false),                  "Enable/Disable internal Downlink channel emulator")
     ("channel.ul.awgn.enable",       bpo::value<bool>(&args->phy.ul_channel_args.awgn_enable)->default_value(false),             "Enable/Disable AWGN simulator")
-    ("channel.ul.awgn.n0", bpo::value<float>(&args->phy.ul_channel_args.awgn_n0_dBfs)->default_value(-30.0f), "Noise level in decibels full scale (dBfs)")
+    ("channel.ul.awgn.signal_power", bpo::value<float>(&args->phy.ul_channel_args.awgn_signal_power_dBfs)->default_value(30.0f), "Received signal power in decibels full scale (dBfs)")
+    ("channel.ul.awgn.snr",          bpo::value<float>(&args->phy.ul_channel_args.awgn_snr_dB)->default_value(30.0f),            "Noise level in decibels full scale (dBfs)")
     ("channel.ul.fading.enable",     bpo::value<bool>(&args->phy.ul_channel_args.fading_enable)->default_value(false),           "Enable/Disable Fading model")
     ("channel.ul.fading.model",      bpo::value<std::string>(&args->phy.ul_channel_args.fading_model)->default_value("none"),    "Fading model + maximum doppler (E.g. none, epa5, eva70, etu300, etc)")
     ("channel.ul.delay.enable",      bpo::value<bool>(&args->phy.ul_channel_args.delay_enable)->default_value(false),            "Enable/Disable Delay simulator")
@@ -175,7 +176,7 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     ("channel.ul.rlf.t_off_ms",      bpo::value<uint32_t >(&args->phy.ul_channel_args.rlf_t_off_ms)->default_value(2000),        "Time for Off state of the channel (ms)")
     ("channel.ul.hst.enable",        bpo::value<bool>(&args->phy.ul_channel_args.hst_enable)->default_value(false),              "Enable/Disable HST simulator")
     ("channel.ul.hst.period_s",      bpo::value<float>(&args->phy.ul_channel_args.hst_period_s)->default_value(7.2f),            "HST simulation period in seconds")
-    ("channel.ul.hst.fd_hz", bpo::value<float>(&args->phy.ul_channel_args.hst_fd_hz)->default_value(-750.0f), "Doppler frequency in Hz")
+    ("channel.ul.hst.fd_hz",         bpo::value<float>(&args->phy.ul_channel_args.hst_fd_hz)->default_value(+750.0f),            "Doppler frequency in Hz")
     ("channel.ul.hst.init_time_s",   bpo::value<float>(&args->phy.ul_channel_args.hst_init_time_s)->default_value(0),            "Initial time in seconds")
 
       /* Expert section */

srsenb/src/phy/phy_common.cc

@@ -70,6 +70,7 @@ bool phy_common::init(const phy_cell_cfg_list_t&   cell_list_,
   if (params.dl_channel_args.enable) {
     dl_channel = srslte::channel_ptr(new srslte::channel(params.dl_channel_args, get_nof_rf_channels()));
     dl_channel->set_srate((uint32_t)srslte_sampling_freq_hz(cell_list[0].cell.nof_prb));
+    dl_channel->set_signal_power_dBfs(srslte_enb_dl_get_maximum_signal_power_dBfs(cell_list[0].cell.nof_prb));
   }
 
   // Create grants
@@ -124,9 +125,7 @@ void phy_common::set_ul_grants(uint32_t tti, const stack_interface_phy_lte::ul_s
  * Each worker uses this function to indicate that all processing is done and data is ready for transmission or
  * there is no transmission at all (tx_enable). In that case, the end of burst message will be sent to the radio
  */
-void phy_common::worker_end(void*                   tx_sem_id,
+void phy_common::worker_end(void* tx_sem_id, srslte::rf_buffer_t& buffer, srslte::rf_timestamp_t& tx_time)
-                            srslte::rf_buffer_t&    buffer,
-                            srslte::rf_timestamp_t& tx_time)
 {
   // Wait for the green light to transmit in the current TTI
   semaphore.wait(tx_sem_id);

srsue/src/main.cc

@@ -184,7 +184,8 @@ static int parse_args(all_args_t* args, int argc, char* argv[])
     /* Downlink Channel emulator section */
     ("channel.dl.enable",            bpo::value<bool>(&args->phy.dl_channel_args.enable)->default_value(false),                 "Enable/Disable internal Downlink channel emulator")
     ("channel.dl.awgn.enable",       bpo::value<bool>(&args->phy.dl_channel_args.awgn_enable)->default_value(false),            "Enable/Disable AWGN simulator")
-    ("channel.dl.awgn.n0", bpo::value<float>(&args->phy.dl_channel_args.awgn_n0_dBfs)->default_value(-30.0f), "Noise level in decibels full scale (dBfs)")
+    ("channel.dl.awgn.snr",          bpo::value<float>(&args->phy.dl_channel_args.awgn_snr_dB)->default_value(30.0f),           "Noise level in decibels full scale (dBfs)")
+    ("channel.dl.awgn.signal_power", bpo::value<float>(&args->phy.dl_channel_args.awgn_signal_power_dBfs)->default_value(0.0f), "Received signal power in decibels full scale (dBfs)")
     ("channel.dl.fading.enable",     bpo::value<bool>(&args->phy.dl_channel_args.fading_enable)->default_value(false),          "Enable/Disable Fading model")
     ("channel.dl.fading.model",      bpo::value<std::string>(&args->phy.dl_channel_args.fading_model)->default_value("none"),   "Fading model + maximum doppler (E.g. none, epa5, eva70, etu300, etc)")
     ("channel.dl.delay.enable",      bpo::value<bool>(&args->phy.dl_channel_args.delay_enable)->default_value(false),           "Enable/Disable Delay simulator")
@@ -201,9 +202,10 @@ static int parse_args(all_args_t* args, int argc, char* argv[])
     ("channel.dl.hst.init_time_s",   bpo::value<float>(&args->phy.dl_channel_args.hst_init_time_s)->default_value(0),           "Initial time in seconds")
 
     /* Uplink Channel emulator section */
-    ("channel.ul.enable", bpo::value<bool>(&args->phy.ul_channel_args.enable)->default_value(false), "Enable/Disable internal Uplink channel emulator")
+    ("channel.ul.enable",            bpo::value<bool>(&args->phy.ul_channel_args.enable)->default_value(false),                  "Enable/Disable internal Downlink channel emulator")
     ("channel.ul.awgn.enable",       bpo::value<bool>(&args->phy.ul_channel_args.awgn_enable)->default_value(false),             "Enable/Disable AWGN simulator")
-    ("channel.ul.awgn.n0", bpo::value<float>(&args->phy.ul_channel_args.awgn_n0_dBfs)->default_value(-30.0f), "Noise level in decibels full scale (dBfs)")
+    ("channel.ul.awgn.snr",          bpo::value<float>(&args->phy.ul_channel_args.awgn_snr_dB)->default_value(30.0f),            "Noise level in decibels full scale (dBfs)")
+    ("channel.ul.awgn.signal_power", bpo::value<float>(&args->phy.ul_channel_args.awgn_signal_power_dBfs)->default_value(30.0f), "Transmitted signal power in decibels full scale (dBfs)")
     ("channel.ul.fading.enable",     bpo::value<bool>(&args->phy.ul_channel_args.fading_enable)->default_value(false),           "Enable/Disable Fading model")
     ("channel.ul.fading.model",      bpo::value<std::string>(&args->phy.ul_channel_args.fading_model)->default_value("none"),    "Fading model + maximum doppler (E.g. none, epa5, eva70, etu300, etc)")
     ("channel.ul.delay.enable",      bpo::value<bool>(&args->phy.ul_channel_args.delay_enable)->default_value(false),            "Enable/Disable Delay simulator")
@@ -216,7 +218,7 @@ static int parse_args(all_args_t* args, int argc, char* argv[])
     ("channel.ul.rlf.t_off_ms",      bpo::value<uint32_t >(&args->phy.ul_channel_args.rlf_t_off_ms)->default_value(2000),        "Time for Off state of the channel (ms)")
     ("channel.ul.hst.enable",        bpo::value<bool>(&args->phy.ul_channel_args.hst_enable)->default_value(false),              "Enable/Disable HST simulator")
     ("channel.ul.hst.period_s",      bpo::value<float>(&args->phy.ul_channel_args.hst_period_s)->default_value(7.2f),            "HST simulation period in seconds")
-    ("channel.ul.hst.fd_hz", bpo::value<float>(&args->phy.ul_channel_args.hst_fd_hz)->default_value(-750.0f), "Doppler frequency in Hz")
+    ("channel.ul.hst.fd_hz",         bpo::value<float>(&args->phy.ul_channel_args.hst_fd_hz)->default_value(+750.0f),            "Doppler frequency in Hz")
     ("channel.ul.hst.init_time_s",   bpo::value<float>(&args->phy.ul_channel_args.hst_init_time_s)->default_value(0),            "Initial time in seconds")
 
     /* PHY section */