Reduced sampling rates (not power of 2 fft sizes)

srslte/examples/pdsch_ue.c

@@ -107,7 +107,7 @@ void args_default(prog_args_t *args) {
   args->file_cell_id = 0; 
   args->uhd_args = "";
   args->uhd_freq = -1.0;
-  args->uhd_freq_offset = 8000000.0;
+  args->uhd_freq_offset = 0.0;
   args->uhd_gain = -1.0; 
   args->net_port = -1; 
   args->net_address = "127.0.0.1";

srslte/include/srslte/common/phy_common.h

@@ -43,8 +43,6 @@
 
 #include "srslte/config.h"
 
-#define USE_REDUCED_SAMPLING_RATES
-
 #define SRSLTE_NSUBFRAMES_X_FRAME  10
 #define SRSLTE_NSLOTS_X_FRAME      (2*SRSLTE_NSUBFRAMES_X_FRAME)
 
@@ -211,6 +209,7 @@ SRSLTE_API bool srslte_symbol_sz_isvalid(uint32_t symbol_sz);
 
 SRSLTE_API int srslte_symbol_sz(uint32_t nof_prb);
 
+SRSLTE_API int srslte_nof_prb(uint32_t symbol_sz);
 
 SRSLTE_API int srslte_sampling_freq_hz(uint32_t nof_prb);
 

srslte/lib/common/src/phy_common.c

@@ -36,6 +36,10 @@
 #include "srslte/common/sequence.h"
 
 
+#define USE_REDUCED_SAMPLING_RATES
+
+
+
 /* Returns true if the structure pointed by cell has valid parameters
  */
 
@@ -229,16 +233,67 @@ int srslte_symbol_sz(uint32_t nof_prb) {
   return SRSLTE_ERROR;
 }
 
+int srslte_nof_prb(uint32_t symbol_sz)
+{
+#ifdef USE_REDUCED_SAMPLING_RATES
+  switch(symbol_sz) {
+    case 128:
+      return 6;
+    case 256:
+      return 15;
+    case 384:
+      return 25;
+    case 768:
+      return 50;
+    case 1024:
+      return 75;
+    case 1536:
+      return 100;
+  }
+#else 
+  switch(symbol_sz) {
+    case 128:
+      return 6;
+    case 256:
+      return 15;
+    case 512:
+      return 25;
+    case 1024:
+      return 50;
+    case 1536:
+      return 75;
+    case 2048:
+      return 100;
+  }
+#endif
+  return SRSLTE_ERROR;
+}
+
 bool srslte_symbol_sz_isvalid(uint32_t symbol_sz) {
+#ifdef USE_REDUCED_SAMPLING_RATES 
+  if (symbol_sz == 128  || 
+      symbol_sz == 256  ||
+      symbol_sz == 384  ||
+      symbol_sz == 768  ||
+      symbol_sz == 1024 ||
+      symbol_sz == 1536) {
+    return true;
+  } else {
+    return false; 
+  }
+#else
   if (symbol_sz == 128  || 
       symbol_sz == 256  ||
       symbol_sz == 512  ||
       symbol_sz == 1024 ||
+      symbol_sz == 1536 ||
       symbol_sz == 2048) {
     return true;
   } else {
     return false; 
   }
+#endif
+  
 }
 
 uint32_t srslte_voffset(uint32_t symbol_id, uint32_t cell_id, uint32_t nof_ports) {

srslte/lib/phch/src/prach.c

@@ -27,6 +27,8 @@
 
 #include <math.h>
 #include <string.h>
+
+#include "srslte/common/phy_common.h"
 #include "srslte/phch/prach.h"
 #include "srslte/utils/debug.h"
 #include "srslte/utils/vector.h"
@@ -222,27 +224,6 @@ void print(void *d, uint32_t size, uint32_t len, char* file_str)
   fclose(f);
 }
 
-uint32_t prach_get_rb_ul(uint32_t N_ifft_ul)
-{
-  switch(N_ifft_ul)
-  {
-  case 128:
-    return 6;
-  case 256:
-    return 15;
-  case 512:
-    return 25;
-  case 1024:
-    return 50;
-  case 1536:
-    return 75;
-  case 2048:
-    return 100;
-  default:
-    return 0;
-  }
-}
-
 int srslte_prach_gen_seqs(srslte_prach_t *p)
 {
   uint32_t u = 0;
@@ -448,7 +429,7 @@ int srslte_prach_gen(srslte_prach_t *p,
      signal     != NULL)
   {
     // Calculate parameters
-    uint32_t N_rb_ul = prach_get_rb_ul(p->N_ifft_ul);
+    uint32_t N_rb_ul = srslte_nof_prb(p->N_ifft_ul);
     uint32_t k_0 = freq_offset*N_RB_SC - N_rb_ul*N_RB_SC/2 + p->N_ifft_ul/2;
     uint32_t K = DELTA_F/DELTA_F_RA;
     uint32_t begin = PHI + (K*k_0) + (K/2);
@@ -501,7 +482,7 @@ int srslte_prach_detect(srslte_prach_t *p,
     *n_indices = 0;
 
     // Extract bins of interest
-    uint32_t N_rb_ul = prach_get_rb_ul(p->N_ifft_ul);
+    uint32_t N_rb_ul = srslte_nof_prb(p->N_ifft_ul);
     uint32_t k_0 = freq_offset*N_RB_SC - N_rb_ul*N_RB_SC/2 + p->N_ifft_ul/2;
     uint32_t K = DELTA_F/DELTA_F_RA;
     uint32_t begin = PHI + (K*k_0) + (K/2);