Fix bug in SRS using the previous grant to compute collision with PUSCH (#958)

lib/include/srslte/phy/phch/ra_ul.h

@@ -61,6 +61,10 @@ SRSLTE_API int srslte_ra_ul_dci_to_grant(srslte_cell_t*              cell,
                                          srslte_dci_ul_t*            dci,
                                          srslte_pusch_grant_t*       grant);
 
+SRSLTE_API void srslte_ra_ul_compute_nof_re(srslte_pusch_grant_t* grant,
+                                            srslte_cp_t cp,
+                                            uint32_t N_srs);
+
 /** Others */
 SRSLTE_API uint32_t srslte_ra_ul_info(srslte_pusch_grant_t* grant, char* info_str, uint32_t len);
 

lib/src/phy/phch/ra_ul.c

@@ -229,7 +229,7 @@ static void ul_fill_ra_mcs(srslte_ra_tb_t* tb, srslte_ra_tb_t* last_tb, uint32_t
   }
 }
 
-static void compute_nof_re(srslte_pusch_grant_t* grant, srslte_cp_t cp, uint32_t N_srs)
+void srslte_ra_ul_compute_nof_re(srslte_pusch_grant_t* grant, srslte_cp_t cp, uint32_t N_srs)
 {
   grant->nof_symb    = 2 * (SRSLTE_CP_NSYMB(cp) - 1) - N_srs;
   grant->nof_re      = grant->nof_symb * grant->L_prb * SRSLTE_NRE;
@@ -299,10 +299,11 @@ int srslte_ra_ul_dci_to_grant(srslte_cell_t*              cell,
     // copy RV
     grant->tb.rv = dci->tb.rv;
 
-    /* Compute final number of bits and RE */
-    compute_nof_re(grant, cell->cp, sf->shortened ? 1 : 0);
+    /* Compute RE assuming shortened is false*/
+    srslte_ra_ul_compute_nof_re(grant, cell->cp, 0);
 
-    // Assume hopping is the same
+    // TODO: Need to compute hopping here before determining if there is collision with SRS, but only MAC knows if it's a
+    //  new tx or a retx. Need to split MAC interface in 2 calls. For now, assume hopping is the same
     for (uint32_t i = 0; i < 2; i++) {
       grant->n_prb_tilde[i] = grant->n_prb[i];
     }

lib/src/phy/ue/ue_ul.c

@@ -207,10 +207,19 @@ int srslte_ue_ul_dci_to_pusch_grant(srslte_ue_ul_t*       q,
                                     srslte_dci_ul_t*      dci,
                                     srslte_pusch_grant_t* grant)
 {
+  if (srslte_ra_ul_dci_to_grant(&q->cell, sf, &cfg->ul_cfg.hopping, dci, grant)) {
+    ERROR("Converting DCI to UL grant\n");
+    return SRSLTE_ERROR;
+  }
+
   // Update shortened before computing grant
   srslte_refsignal_srs_pusch_shortened(&q->signals, sf, &cfg->ul_cfg.srs, &cfg->ul_cfg.pusch);
 
-  return srslte_ra_ul_dci_to_grant(&q->cell, sf, &cfg->ul_cfg.hopping, dci, grant);
+  /* Update RE assuming if shortened is true */
+  if (sf->shortened) {
+    srslte_ra_ul_compute_nof_re(grant, q->cell.cp, true);
+  }
+  return SRSLTE_SUCCESS;
 }
 
 void srslte_ue_ul_pusch_hopping(srslte_ue_ul_t*       q,
@@ -218,6 +227,9 @@ void srslte_ue_ul_pusch_hopping(srslte_ue_ul_t*       q,
                                 srslte_ue_ul_cfg_t*   cfg,
                                 srslte_pusch_grant_t* grant)
 {
+  if (cfg->ul_cfg.srs.configured && cfg->ul_cfg.hopping.hopping_enabled) {
+    ERROR("UL SRS and frequency hopping not currently supported\n");
+  }
   return srslte_ra_ul_pusch_hopping(&q->hopping, sf, &cfg->ul_cfg.hopping, grant);
 }