diff --git a/lib/include/srsran/phy/phch/ra_nr.h b/lib/include/srsran/phy/phch/ra_nr.h
index a2ddd5042..eb008ed1d 100644
--- a/lib/include/srsran/phy/phch/ra_nr.h
+++ b/lib/include/srsran/phy/phch/ra_nr.h
@@ -139,4 +139,13 @@ SRSRAN_API int srsran_ra_ul_set_grant_uci_nr(const srsran_carrier_nr_t*    carri
                                              const srsran_uci_cfg_nr_t*    uci_cfg,
                                              srsran_sch_cfg_nr_t*          pusch_cfg);
 
+/**
+ * @brief Calculates frequency allocation type 1 RIV field
+ * @param N_rb Number of resource blocks
+ * @param start_rb Start resource block index
+ * @param length_rb Number of resource blocks
+ * @return The RIV field with the encoded value
+ */
+SRSRAN_API uint32_t srsran_ra_nr_type1_riv(uint32_t N_rb, uint32_t start_rb, uint32_t length_rb);
+
 #endif // SRSRAN_RA_NR_H
diff --git a/lib/src/phy/phch/ra_dl_nr.c b/lib/src/phy/phch/ra_dl_nr.c
index d3bf524e3..78eb6856f 100644
--- a/lib/src/phy/phch/ra_dl_nr.c
+++ b/lib/src/phy/phch/ra_dl_nr.c
@@ -319,3 +319,8 @@ int srsran_ra_dl_nr_freq(const srsran_carrier_nr_t*    carrier,
   ERROR("Unhandled case");
   return SRSRAN_ERROR;
 }
+
+uint32_t srsran_ra_nr_type1_riv(uint32_t N_prb, uint32_t start_rb, uint32_t length_rb)
+{
+  return ra_helper_from_s_and_l(N_prb, start_rb, length_rb);
+}
\ No newline at end of file
diff --git a/lib/src/phy/phch/ra_helper.h b/lib/src/phy/phch/ra_helper.h
index 029bb6ad6..004bf6075 100644
--- a/lib/src/phy/phch/ra_helper.h
+++ b/lib/src/phy/phch/ra_helper.h
@@ -73,6 +73,14 @@ static inline void ra_helper_compute_s_and_l(uint32_t N, uint32_t v, uint32_t* S
   }
 }
 
+static inline uint32_t ra_helper_from_s_and_l(uint32_t N, uint32_t S, uint32_t L)
+{
+  if ((L - 1) <= N / 2) {
+    return N * (L - 1) + S;
+  }
+  return N * (N - L + 1) + (N - 1 - S);
+}
+
 static int ra_helper_freq_type1(uint32_t N_bwp_size, uint32_t riv, srsran_sch_grant_nr_t* grant)
 {
   uint32_t start = 0;