From e07263ee2607d247b85b7b58b35a822162421f68 Mon Sep 17 00:00:00 2001
From: Xavier Arteaga <xavier@softwareradiosystems.com>
Date: Tue, 17 Aug 2021 13:35:16 +0200
Subject: [PATCH] Added band helper for getting band from ARFCN

---
 lib/include/srsran/common/band_helper.h |  7 +++++++
 lib/src/common/band_helper.cc           | 12 ++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/lib/include/srsran/common/band_helper.h b/lib/include/srsran/common/band_helper.h
index a362a6b29..0ffde42c9 100644
--- a/lib/include/srsran/common/band_helper.h
+++ b/lib/include/srsran/common/band_helper.h
@@ -52,6 +52,13 @@ public:
    */
   uint16_t get_band_from_dl_freq_Hz(double dl_freq_Hz) const;
 
+  /**
+   * @brief Get the lowest band that includes a given Downlink ARFCN
+   * @param arfcn Given ARFCN
+   * @return The band number if the ARFCN is bounded in a band, UINT16_MAX otherwise
+   */
+  uint16_t get_band_from_dl_arfcn(uint32_t arfcn) const;
+
   /**
    * @brief Selects the SSB pattern case according to the band number and subcarrier spacing
    * @remark Described by TS 38.101-1 Table 5.4.3.3-1: Applicable SS raster entries per operating band
diff --git a/lib/src/common/band_helper.cc b/lib/src/common/band_helper.cc
index 76e2821e1..5b760a480 100644
--- a/lib/src/common/band_helper.cc
+++ b/lib/src/common/band_helper.cc
@@ -67,6 +67,18 @@ uint16_t srsran_band_helper::get_band_from_dl_freq_Hz(double freq) const
   return UINT16_MAX;
 }
 
+uint16_t srsran_band_helper::get_band_from_dl_arfcn(uint32_t arfcn) const
+{
+  for (const nr_band& band : nr_band_table_fr1) {
+    // Check given ARFCN is between the first and last possible ARFCN and matches step
+    if (arfcn >= band.dl_nref_first and arfcn <= band.dl_nref_last and
+        (arfcn - band.dl_nref_first) % band.dl_nref_step == 0) {
+      return band.band;
+    }
+  }
+  return UINT16_MAX;
+}
+
 srsran_ssb_patern_t srsran_band_helper::get_ssb_pattern(uint16_t band, srsran_subcarrier_spacing_t scs) const
 {
   // Look for the given band and SCS