Enable PTRS with command line in ULSIM

- To enable PTRS use -T flag followed by 3 integers
- Example: ./nr_ulsim -T 2 0 2
- 1st Value is the list of arguments -> e.g. 2
- 2nd Value is for L_PTRS{0,1,2}     -> e.g. 0
- 3rd Value is for K_PTRS{2,4}       -> e.g. 2

openair1/PHY/NR_ESTIMATION/nr_ul_channel_estimation.c

@@ -672,8 +672,8 @@ void nr_pusch_phase_estimation(NR_DL_FRAME_PARMS *frame_parms,
   uint16_t              re_cnt           = 0;
   uint16_t              cnt              = 0;
   unsigned short        nb_re_pusch      = NR_NB_SC_PER_RB * rel15_ul->rb_size;
-  uint8_t               K_ptrs           = (rel15_ul->pusch_ptrs.ptrs_freq_density)?4:2;
-  uint16_t              sc_per_symbol    = rel15_ul->rb_size/K_ptrs;
+  uint8_t               K_ptrs           = rel15_ul->pusch_ptrs.ptrs_freq_density;
+  uint16_t              sc_per_symbol    = (rel15_ul->rb_size + K_ptrs - 1)/K_ptrs;
   int16_t              *ptrs_p           = (int16_t *)malloc(sizeof(int32_t)*(sc_per_symbol));
   int16_t              *dmrs_comp_p      = (int16_t *)malloc(sizeof(int32_t)*(sc_per_symbol));
   double                abs              = 0.0;
@@ -683,7 +683,7 @@ void nr_pusch_phase_estimation(NR_DL_FRAME_PARMS *frame_parms,
   double                alpha            = 0;
 #endif
   /* generate PTRS RE for the symbol */
-  nr_ptrs_rx_gen(ptrs_gold_seq[Ns][symbol],rel15_ul->rb_size,ptrs_p);
+  nr_gen_ref_conj_symbols(ptrs_gold_seq[Ns][symbol],sc_per_symbol*2,ptrs_p, NR_MOD_TABLE_QPSK_OFFSET,2);// 2 for QPSK
 
   /* loop over all sub carriers to get compensated RE on ptrs symbols*/
   for (int re = 0; re < nb_re_pusch; re++)

openair1/PHY/NR_REFSIG/nr_dmrs_rx.c

@@ -230,12 +230,9 @@ int nr_pbch_dmrs_rx(int symbol,
   \param length is number of RE in a OFDM symbol
   \param *output pointer to all ptrs RE in a OFDM symbol
 */
-void nr_ptrs_rx_gen(uint32_t *in, uint32_t length, int16_t *output)
+void nr_gen_ref_conj_symbols(uint32_t *in, uint32_t length, int16_t *output, uint16_t offset, int mod_order)
 {
-  uint16_t offset;
   uint8_t idx, b_idx;
-  int mod_order = 2;
-  offset = NR_MOD_TABLE_QPSK_OFFSET;
   for (int i=0; i<length/mod_order; i++)
     {
       idx = 0;

openair1/PHY/NR_REFSIG/nr_refsig.h

@@ -52,7 +52,7 @@ int nr_pusch_dmrs_rx(PHY_VARS_gNB *gNB,
                      uint8_t dmrs_type);
 
 void init_scrambling_luts(void);
-void nr_ptrs_rx_gen(uint32_t *in, uint32_t length, int16_t *output);
+void nr_gen_ref_conj_symbols(uint32_t *in, uint32_t length, int16_t *output, uint16_t offset, int mod_order);
 uint8_t get_next_dmrs_symbol_in_slot(uint16_t  ul_dmrs_symb_pos, uint8_t counter, uint8_t end_symbol);
 uint8_t get_dmrs_symbols_in_slot(uint16_t l_prime_mask,  uint16_t nb_symb);
 

openair1/PHY/NR_UE_TRANSPORT/nr_ulsch_ue.c

@@ -281,7 +281,7 @@ void nr_ue_ulsch_procedures(PHY_VARS_NR_UE *UE,
 
   if (harq_process_ul_ue->pusch_pdu.pdu_bit_map & PUSCH_PDU_BITMAP_PUSCH_PTRS) {
 
-    K_ptrs = (harq_process_ul_ue->pusch_pdu.pusch_ptrs.ptrs_freq_density)?4:2;
+    K_ptrs = harq_process_ul_ue->pusch_pdu.pusch_ptrs.ptrs_freq_density;
     L_ptrs = 1<<harq_process_ul_ue->pusch_pdu.pusch_ptrs.ptrs_time_density;
 
     beta_ptrs = 1; // temp value until power control is implemented

openair1/SIMULATION/NR_PHY/ulsim.c

@@ -149,7 +149,8 @@ int main(int argc, char **argv)
 
   UE_nr_rxtx_proc_t UE_proc;
   FILE *scg_fd=NULL;
-
+  int enable_ptrs = 0;
+  int ptrs_arg[2] = {-1,-1};
   int ibwps=24;
   int ibwp_rboffset=41;
   if ( load_configmodule(argc,argv,CONFIG_ENABLECMDLINEONLY) == 0 ) {
@@ -159,7 +160,7 @@ int main(int argc, char **argv)
   //logInit();
   randominit(0);
 
-  while ((c = getopt(argc, argv, "a:b:c:d:ef:g:h:i:j:kl:m:n:p:r:s:y:z:F:M:N:PR:S:L:")) != -1) {
+  while ((c = getopt(argc, argv, "a:b:c:d:ef:g:h:i:j:kl:m:n:p:r:s:y:z:F:M:N:PR:S:T:L:")) != -1) {
     printf("handling optarg %c\n",c);
     switch (c) {
 
@@ -345,6 +346,15 @@ int main(int argc, char **argv)
     case 'L':
       loglvl = atoi(optarg);
       break;
+
+   case 'T':
+      enable_ptrs=1;
+      int i = 0;
+      for(; optind < argc; optind++){
+        ptrs_arg[i] = atoi(argv[optind]);
+        i++;
+      }
+      break;
       
     default:
     case 'h':
@@ -374,6 +384,7 @@ int main(int argc, char **argv)
       printf("-R N_RB_DL\n");
       printf("-S Ending SNR, runs from SNR0 to SNR1\n");
       printf("-P Print ULSCH performances\n");
+      printf("-T Enable PTRS, arguments list L_PTRS{0,1,2} K_PTRS{2,4}, e.g. -T 2 0 2 \n");
       exit(-1);
       break;
 
@@ -565,6 +576,21 @@ int main(int argc, char **argv)
   double ts = 1.0/(frame_parms->subcarrier_spacing * frame_parms->ofdm_symbol_size);
 
   number_dmrs_symbols = get_dmrs_symbols_in_slot(l_prime_mask, nb_symb_sch);
+  /* -T option enable PTRS */
+  if(enable_ptrs)
+  {
+    /* validate parameters othwerwise default values are used */
+    if(ptrs_arg[0] == 0 || ptrs_arg[0] == 1 || ptrs_arg[0] == 2 )
+    {
+      ptrs_time_density = ptrs_arg[0];
+    }
+    if(ptrs_arg[1] == 2 || ptrs_arg[1] == 4 )
+    {
+      ptrs_freq_density = ptrs_arg[1];
+    }
+    pdu_bit_map |= PUSCH_PDU_BITMAP_PUSCH_PTRS;
+    printf("PTRS Enabled with L %d, K %d \n",ptrs_time_density, ptrs_freq_density );
+  }
 
   if(1<<ptrs_time_density >= nb_symb_sch)
     pdu_bit_map &= ~PUSCH_PDU_BITMAP_PUSCH_PTRS; // disable PUSCH PTRS
@@ -849,7 +875,7 @@ int main(int argc, char **argv)
                ptrs_symbols += ((gNB->pusch_vars[UE_id]->ptrs_symbols) >> i) & 1;
             }
             /*  2*5*(50/2), for RB = 50,K = 2 for 5 OFDM PTRS symbols */
-            available_bits = available_bits - (2 * ptrs_symbols * (nb_rb/((ptrs_freq_density)?4:2)));
+            available_bits -= 2 * ptrs_symbols * ((pusch_pdu->rb_size + ptrs_freq_density - 1) /ptrs_freq_density);
             printf("After PTRS subtraction available_bits are : %d \n", available_bits);
         }
 

openair2/LAYER2/NR_MAC_COMMON/nr_mac_common.c

@@ -1875,9 +1875,9 @@ uint8_t get_K_ptrs(uint16_t nrb0, uint16_t nrb1, uint16_t N_RB) {
     LOG_I(PHY,"PUSH PT-RS is not present.\n");
     return -1;
   } else if (N_RB >= nrb0 && N_RB < nrb1)
-    return 0;
+    return 2;
   else
-    return 1;
+    return 4;
 }
 
 uint16_t nr_dci_size(NR_ServingCellConfigCommon_t *scc,