Fix prach K,kbar for mu 0

common/utils/nr/nr_common.c

@@ -1298,6 +1298,47 @@ uint8_t get_long_prach_dur(unsigned int format, unsigned int mu)
   return (prach_dur_subframes * num_slots_subframe);
 }
 
+// Table 38.211 6.3.3.2-1
+uint8_t get_PRACH_k_bar(unsigned int delta_f_RA_PRACH, unsigned int delta_f_PUSCH)
+{
+  uint8_t k_bar = 0;
+  if (delta_f_RA_PRACH > 3) { // Rel 15 max PRACH SCS is 120 kHz, 4 and 5 are 1.25 and 5 kHz
+    // long formats
+    DevAssert(delta_f_PUSCH < 3);
+    DevAssert(delta_f_RA_PRACH < 6);
+    const uint8_t k_bar_table[3][2] = {{7, 12},
+                                       {1, 10},
+                                       {133, 7}};
+
+    k_bar = k_bar_table[delta_f_PUSCH][delta_f_RA_PRACH - 4];
+  } else {
+    if (delta_f_RA_PRACH == 3 && delta_f_PUSCH == 4) // \delta f_RA == 120 kHz AND \delta f == 480 kHz
+      k_bar = 1;
+    else if (delta_f_RA_PRACH == 3 && delta_f_PUSCH == 5) // \delta f_RA == 120 kHz AND \delta f == 960 kHz
+      k_bar = 23;
+    else
+      k_bar = 2;
+  }
+  return k_bar;
+}
+
+// K according to 38.211 5.3.2
+unsigned int get_prach_K(int prach_sequence_length, int prach_fmt_id, int pusch_mu, int prach_mu)
+{
+  unsigned int K = 1;
+  if (prach_sequence_length == 0) {
+    if (prach_fmt_id == 3)
+      K = (15 << pusch_mu) / 5;
+    else
+      K = (15 << pusch_mu) / 1.25;
+  } else if (prach_sequence_length == 1) {
+    K = (15 << pusch_mu) / (15 << prach_mu);
+  } else {
+    AssertFatal(0, "Invalid PRACH sequence length %d\n", prach_sequence_length);
+  }
+  return K;
+}
+
 int get_delay_idx(int delay, int max_delay_comp)
 {
   int delay_idx = max_delay_comp + delay;

common/utils/nr/nr_common.h

@@ -288,6 +288,8 @@ int get_smallest_supported_bandwidth_index(int scs, frequency_range_t frequency_
 unsigned short get_m_srs(int c_srs, int b_srs);
 unsigned short get_N_b_srs(int c_srs, int b_srs);
 uint8_t get_long_prach_dur(unsigned int format, unsigned int num_slots_subframe);
+uint8_t get_PRACH_k_bar(unsigned int delta_f_RA_PRACH, unsigned int delta_f_PUSCH);
+unsigned int get_prach_K(int prach_sequence_length, int prach_fmt_id, int pusch_mu, int prach_mu);
 
 int get_slot_idx_in_period(const int slot, const frame_structure_t *fs);
 

openair1/PHY/NR_TRANSPORT/nr_prach.c

@@ -165,6 +165,7 @@ void rx_nr_prach_ru(RU_t *ru,
   int16_t *prach[ru->nb_rx];
   int prach_sequence_length = ru->config.prach_config.prach_sequence_length.value;
   int msg1_frequencystart = ru->config.prach_config.num_prach_fd_occasions_list[numRA].k1.value;
+  const uint8_t prach_mu = ru->config.prach_config.prach_sub_c_spacing.value;
 
   int sample_offset_slot;
   if (prachStartSymbol == 0) {
@@ -391,18 +392,9 @@ void rx_nr_prach_ru(RU_t *ru,
     LOG_D(PHY, "rx_prach: Doing PRACH FFT for nb_rx:%d Ncp:%d dftlen:%d\n", ru->nb_rx, Ncp, dftlen);
   }
 
-  // Note: Assumes PUSCH SCS @ 30 kHz, take values for formats 0-2 and adjust for others below
-  int kbar = 1;
-  int K    = 24;
-  if (prach_sequence_length == 0 && prachFormat == 3) { 
-    K=4;
-    kbar=10;
-  }
-  else if (prach_sequence_length == 1) {
-    // Note: Assumes that PRACH SCS is same as PUSCH SCS
-    K=1;
-    kbar=2;
-  }
+  const unsigned int K = get_prach_K(prach_sequence_length, prachFormat, fp->numerology_index, prach_mu);
+  const uint8_t kbar = get_PRACH_k_bar(prach_mu, fp->numerology_index);
+
   int n_ra_prb            = msg1_frequencystart;
   int k                   = (12*n_ra_prb) - 6*fp->N_RB_UL;
 

openair1/PHY/NR_UE_TRANSPORT/nr_prach.c

@@ -66,7 +66,7 @@ int32_t generate_nr_prach(PHY_VARS_NR_UE *ue, uint8_t gNB_id, int frame, uint8_t
   c16_t prachF_tmp[(4688 + 4 * 24576) * 4] __attribute__((aligned(32))) = {0};
 
   int Ncp = 0;
-  int prach_start, prach_sequence_length, prach_len, dftlen, mu, kbar, K, n_ra_prb, k, prachStartSymbol, sample_offset_slot;
+  int prach_start, prach_sequence_length, prach_len, dftlen, mu, n_ra_prb, k, prachStartSymbol, sample_offset_slot;
 
   fd_occasion             = 0;
   prach_len               = 0;
@@ -83,9 +83,7 @@ int32_t generate_nr_prach(PHY_VARS_NR_UE *ue, uint8_t gNB_id, int frame, uint8_t
   n_ra_prb                = nrUE_config->prach_config.num_prach_fd_occasions_list[fd_occasion].k1,//prach_pdu->freq_msg1;
   NCS                     = prach_pdu->num_cs;
   prach_fmt_id            = prach_pdu->prach_format;
-  preamble_index          = prach_pdu->ra_PreambleIndex;
-  kbar                    = 1;
-  K                       = 24;
+  preamble_index = prach_pdu->ra_PreambleIndex;
   k                       = 12*n_ra_prb - 6*fp->N_RB_UL;
   prachStartSymbol        = prach_pdu->prach_start_symbol;
 
@@ -214,15 +212,10 @@ int32_t generate_nr_prach(PHY_VARS_NR_UE *ue, uint8_t gNB_id, int frame, uint8_t
   //  nsymb = (frame_parms->Ncp==0) ? 14:12;
   //  subframe_offset = (unsigned int)frame_parms->ofdm_symbol_size*slot*nsymb;
 
-  if (prach_sequence_length == 0 && prach_fmt_id == 3) {
-    K = 4;
-    kbar = 10;
-  } else if (prach_sequence_length == 1) {
-    K = 1;
-    kbar = 2;
-  }
+  const unsigned int K = get_prach_K(prach_sequence_length, prach_fmt_id, fp->numerology_index, mu);
+  const uint8_t kbar = get_PRACH_k_bar(mu, fp->numerology_index);
 
-  if (k<0)
+  if (k < 0)
     k += fp->ofdm_symbol_size;
 
   k *= K;
@@ -265,7 +258,7 @@ int32_t generate_nr_prach(PHY_VARS_NR_UE *ue, uint8_t gNB_id, int frame, uint8_t
       break;
 
     default:
-      AssertFatal(1==0, "Illegal PRACH format %d for sequence length 839\n", prach_fmt_id);
+      AssertFatal(1 == 0, "Illegal PRACH format %d for sequence length 839\n", prach_fmt_id);
       break;
     }
   } else {

openair1/SIMULATION/NR_PHY/prachsim.c

@@ -562,6 +562,7 @@ int main(int argc, char **argv){
   prach_config->num_prach_fd_occasions_list[fd_occasion].k1.value                        = msg1_frequencystart;
   prach_config->restricted_set_config.value                                              = restrictedSetConfig;
   prach_config->prach_sequence_length.value                                              = prach_sequence_length;
+  prach_config->prach_sub_c_spacing.value                                                = mu;
   prach_pdu->num_cs                                                                      = get_NCS(NCS_config, format0, restrictedSetConfig);
   prach_config->num_prach_fd_occasions_list[fd_occasion].num_root_sequences.value        = 1+(64/(N_ZC/prach_pdu->num_cs));
   prach_pdu->prach_format                                                                = prach_format;