Added safe and good quality random generator in phy/utils

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

@@ -58,7 +58,7 @@ typedef struct {
   cf_t* state; // Length fft_size/2
 } srslte_channel_fading_t;
 
-SRSLTE_API int srslte_channel_fading_init(srslte_channel_fading_t* q, double srate, const char* model);
+SRSLTE_API int srslte_channel_fading_init(srslte_channel_fading_t* q, double srate, const char* model, uint32_t seed);
 
 SRSLTE_API void srslte_channel_fading_free(srslte_channel_fading_t* q);
 

lib/include/srslte/phy/utils/random.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2013-2019 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#ifndef SRSLTE_RANDOM_H
+#define SRSLTE_RANDOM_H
+
+#include "srslte/config.h"
+
+#include <inttypes.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef void* srslte_random_t;
+
+SRSLTE_API srslte_random_t* srslte_random_init(uint32_t seed);
+
+SRSLTE_API int srslte_random_uniform_int_dist(srslte_random_t* q, int min, int max);
+
+SRSLTE_API float srslte_random_uniform_real_dist(srslte_random_t* q, float min, float max);
+
+SRSLTE_API float srslte_random_gauss_dist(srslte_random_t* q, float std_dev);
+
+SRSLTE_API void srslte_random_free(srslte_random_t* q);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // SRSLTE_RANDOM_H

lib/src/phy/channel/fading.c

@@ -20,6 +20,7 @@
  */
 
 #include "srslte/phy/channel/fading.h"
+#include "srslte/phy/utils/random.h"
 #include "srslte/phy/utils/vector.h"
 
 #include <complex.h>
@@ -147,7 +148,7 @@ static void filter_segment(srslte_channel_fading_t* q, const cf_t* input, cf_t*
   bzero(&q->state[q->N - nsamples], sizeof(cf_t) * nsamples);
 }
 
-int srslte_channel_fading_init(srslte_channel_fading_t* q, double srate, const char* model)
+int srslte_channel_fading_init(srslte_channel_fading_t* q, double srate, const char* model, uint32_t seed)
 {
   int ret = SRSLTE_ERROR;
 
@@ -166,12 +167,20 @@ int srslte_channel_fading_init(srslte_channel_fading_t* q, double srate, const c
                           round(log2(excess_tap_delay_ns[q->model][nof_taps[q->model] - 1] * 1e-9 * srate)) + 3),
                       64);
     q->path_delay = q->N / 4;
+
+    // Initialise random number
+    srslte_random_t* random = srslte_random_init(seed);
+
+    // Initialise values
     for (int i = 0; i < nof_taps[q->model]; i++) {
-      q->coeff_a[i] = (((double)rand() / (double)RAND_MAX) * (COEFF_A_MAX - COEFF_A_MIN)) + COEFF_A_MIN;
+      q->coeff_a[i] = srslte_random_uniform_real_dist(random, COEFF_A_MIN, COEFF_A_MAX);
       q->coeff_w[i] = 2.0 * M_PI * q->doppler / q->coeff_a[i];
-      q->coeff_p[i] = ((double)rand() / (double)RAND_MAX) * M_PI / 2.0;
+      q->coeff_p[i] = srslte_random_uniform_real_dist(random, 0, (float)M_PI / 2.0f);
     }
 
+    // Free random
+    srslte_random_free(random);
+
     // Plan FFT
     if (srslte_dft_plan_c(&q->fft, q->N, SRSLTE_DFT_FORWARD) != SRSLTE_SUCCESS) {
       fprintf(stderr, "Error: planning fft\n");

lib/src/phy/channel/test/fading_channel_test.c

@@ -41,6 +41,7 @@ static char     default_model[] = "epa5";
 static uint32_t duration_ms     = 1000;
 static char*    model           = default_model;
 static uint32_t srate           = (uint32_t)30.72e6;
+static uint32_t random_seed     = 0x12345678; // Default seed, deterministic channel
 
 #define INPUT_TYPE 0 /* 0: Dirac Delta; Otherwise: Random*/
 
@@ -50,6 +51,7 @@ static void usage(char* prog)
   printf("\t-m Channel model: epa5, eva70, etu300 [Default %s]\n", model);
   printf("\t-t Simulation time in ms: [Default %d]\n", duration_ms);
   printf("\t-s Sampling rate in Hz: [Default %d]\n", srate);
+  printf("\t-r Random generator seed: [Default %d]\n", random_seed);
 #ifdef ENABLE_GUI
   printf("\t-g Enable GUI: [Default %s]\n", enable_gui ? "enabled" : "disabled");
 #endif /* ENABLE_GUI */
@@ -58,7 +60,7 @@ static void usage(char* prog)
 static void parse_args(int argc, char** argv)
 {
   int opt;
-  while ((opt = getopt(argc, argv, "mtsg")) != -1) {
+  while ((opt = getopt(argc, argv, "mtsrg")) != -1) {
     switch (opt) {
       case 'm':
         model = argv[optind];
@@ -69,6 +71,9 @@ static void parse_args(int argc, char** argv)
       case 's':
         srate = (uint32_t)atof(argv[optind]);
         break;
+      case 'r':
+        random_seed = (uint32_t)atoi(argv[optind]);
+        break;
 #ifdef ENABLE_GUI
       case 'g':
         enable_gui ^= true;
@@ -146,7 +151,7 @@ int main(int argc, char** argv)
 #endif /* ENABLE_GUI */
 
   // Initialise channel
-  if (srslte_channel_fading_init(&channel_fading, srate, model)) {
+  if (srslte_channel_fading_init(&channel_fading, srate, model, 0x12345678)) {
     fprintf(stderr, "Error: initialising fading channel. model=%s, srate=%d\n", model, srate);
     goto clean_exit;
   }

lib/src/phy/utils/CMakeLists.txt

@@ -18,7 +18,7 @@
 # and at http://www.gnu.org/licenses/.
 #
 
-file(GLOB SOURCES "*.c")
+file(GLOB SOURCES "*.c" "*.cpp")
 add_library(srslte_utils OBJECT ${SOURCES})
 
 if(VOLK_FOUND)

lib/src/phy/utils/random.cpp

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2013-2019 Software Radio Systems Limited
+ *
+ * This file is part of srsLTE.
+ *
+ * srsLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * srsLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * A copy of the GNU Affero General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#include "srslte/phy/utils/random.h"
+#include <random>
+
+class random_wrap
+{
+private:
+  std::mt19937* mt19937;
+
+public:
+  explicit random_wrap(uint32_t seed) { mt19937 = new std::mt19937(seed); }
+
+  ~random_wrap() { delete mt19937; }
+
+  float uniform_real_dist(float min, float max)
+  {
+    std::uniform_real_distribution<float> dist(min, max);
+    return dist(*mt19937);
+  }
+
+  int uniform_int_dist(int min, int max)
+  {
+    std::uniform_int_distribution<int> dist(min, max);
+    return dist(*mt19937);
+  }
+
+  float gauss_dist(float sigma)
+  {
+    std::normal_distribution<float> dist(sigma);
+    return dist(*mt19937);
+  }
+};
+
+extern "C" {
+
+srslte_random_t* srslte_random_init(uint32_t seed)
+{
+  return (srslte_random_t*)(new random_wrap(seed));
+}
+
+int srslte_random_uniform_int_dist(srslte_random_t* q, int min, int max)
+{
+  int ret = 0;
+
+  if (q) {
+    auto* h = (random_wrap*)q;
+    ret     = h->uniform_int_dist(min, max);
+  }
+
+  return ret;
+}
+
+float srslte_random_uniform_real_dist(srslte_random_t* q, float min, float max)
+{
+  float ret = NAN;
+
+  if (q) {
+    auto* h = (random_wrap*)q;
+    ret     = h->uniform_real_dist(min, max);
+  }
+
+  return ret;
+}
+
+float srslte_random_gauss_dist(srslte_random_t* q, float std_dev)
+{
+  float ret = NAN;
+
+  if (q) {
+    auto* h = (random_wrap*)q;
+    ret     = h->gauss_dist(std_dev);
+  }
+
+  return ret;
+}
+
+void srslte_random_free(srslte_random_t* q)
+{
+  if (q) {
+    delete (random_wrap*)q;
+  }
+}
+}