diff --git a/lib/include/srsran/interfaces/ue_nr_interfaces.h b/lib/include/srsran/interfaces/ue_nr_interfaces.h
index 0ffdf884f..fa86613f4 100644
--- a/lib/include/srsran/interfaces/ue_nr_interfaces.h
+++ b/lib/include/srsran/interfaces/ue_nr_interfaces.h
@@ -93,6 +93,14 @@ public:
    * @param ul_carrier_id The UL carrier used for Msg1 transmission (0 for NUL carrier, and 1 for SUL carrier).
    */
   virtual void prach_sent(uint32_t tti, uint32_t s_id, uint32_t t_id, uint32_t f_id, uint32_t ul_carrier_id) = 0;
+
+  /**
+   * @brief Indicate a valid SR transmission occasion on the valid PUCCH resource for SR configured; and the SR
+   * transmission occasion does not overlap with a measurement gap; and the PUCCH resource for the SR transmission
+   * occasion does not overlap with a UL-SCH resource;
+   * @param tti  The TTI from the PHY viewpoint at which the SR occasion was sent over-the-air (not to the radio).
+   */
+  virtual bool sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx) = 0;
 };
 
 class mac_interface_rrc_nr
@@ -163,8 +171,17 @@ public:
                           const float    preamble_received_target_power,
                           const float    ta_base_sec = 0.0f) = 0;
 
-  /// Instruct PHY to transmit SR for a given identifier
-  virtual void sr_send(uint32_t sr_id) = 0;
+  /**
+   * @brief Query PHY if there is a valid PUCCH SR resource configured for a given SR identifier
+   * @param sr_id SR identifier
+   * @return True if there is a valid PUCCH resource configured
+   */
+  virtual bool has_valid_sr_resource(uint32_t sr_id) = 0;
+
+  /**
+   * @brief Clear any configured downlink assignments and uplink grants
+   */
+  virtual void clear_pending_grants() = 0;
 };
 
 class phy_interface_rrc_nr
diff --git a/srsue/hdr/phy/nr/state.h b/srsue/hdr/phy/nr/state.h
index 90a70fd42..3144298d7 100644
--- a/srsue/hdr/phy/nr/state.h
+++ b/srsue/hdr/phy/nr/state.h
@@ -259,7 +259,26 @@ public:
 
   void reset() { pending_sr_id.clear(); }
 
-  void set_pending_sr(uint32_t value) { pending_sr_id.insert(value); }
+  bool has_valid_sr_resource(uint32_t sr_id)
+  {
+    for (const srsran_pucch_nr_sr_resource_t& r : cfg.pucch.sr_resources) {
+      if (r.configured && r.sr_id == sr_id) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  void clear_pending_grants()
+  {
+    // Scope mutex to protect read/write the list
+    std::lock_guard<std::mutex> lock(pending_ul_grant_mutex);
+
+    // Clear all PDSCH assignments and PUSCH grants
+    pending_dl_grant = {};
+    pending_ul_grant = {};
+    pending_ack      = {};
+  }
 
   void get_pending_sr(const uint32_t& tti, srsran_uci_data_nr_t& uci_data)
   {
diff --git a/srsue/hdr/phy/nr/worker_pool.h b/srsue/hdr/phy/nr/worker_pool.h
index 55eb3f9c3..7f435ceba 100644
--- a/srsue/hdr/phy/nr/worker_pool.h
+++ b/srsue/hdr/phy/nr/worker_pool.h
@@ -40,7 +40,8 @@ public:
   void       send_prach(uint32_t prach_occasion, uint32_t preamble_index, int preamble_received_target_power);
   int  set_ul_grant(std::array<uint8_t, SRSRAN_RAR_UL_GRANT_NBITS> array, uint16_t rnti, srsran_rnti_type_t rnti_type);
   bool set_config(const srsran::phy_cfg_nr_t& cfg);
-  void       sr_send(uint32_t sr_id);
+  bool       has_valid_sr_resource(uint32_t sr_id);
+  void       clear_pending_grants();
 };
 
 } // namespace nr
diff --git a/srsue/hdr/phy/phy.h b/srsue/hdr/phy/phy.h
index a7643929d..3632073da 100644
--- a/srsue/hdr/phy/phy.h
+++ b/srsue/hdr/phy/phy.h
@@ -176,7 +176,8 @@ public:
                   const float    ta_base_sec = 0.0f) final;
   int  tx_request(const tx_request_t& request) final;
   void set_earfcn(std::vector<uint32_t> earfcns) final;
-  void sr_send(uint32_t sr_id) final;
+  bool has_valid_sr_resource(uint32_t sr_id) final;
+  void clear_pending_grants() final;
 
 private:
   void run_thread() final;
diff --git a/srsue/hdr/phy/vnf_phy_nr.h b/srsue/hdr/phy/vnf_phy_nr.h
index c81f667f4..fd685264d 100644
--- a/srsue/hdr/phy/vnf_phy_nr.h
+++ b/srsue/hdr/phy/vnf_phy_nr.h
@@ -57,7 +57,8 @@ public:
                   const int      prach_occasion,
                   const float    target_power_dbm,
                   const float    ta_base_sec = 0.0f) override{};
-  void sr_send(uint32_t sr_id) override;
+  bool has_valid_sr_resource(uint32_t sr_id) override;
+  void clear_pending_grants() override;
 
 private:
   std::unique_ptr<srsran::srsran_basic_vnf> vnf;
diff --git a/srsue/hdr/stack/mac_nr/mac_nr.h b/srsue/hdr/stack/mac_nr/mac_nr.h
index cb58f5d04..d5ea4e899 100644
--- a/srsue/hdr/stack/mac_nr/mac_nr.h
+++ b/srsue/hdr/stack/mac_nr/mac_nr.h
@@ -29,8 +29,7 @@ namespace srsue {
 
 class rlc_interface_mac;
 
-struct mac_nr_args_t {
-};
+struct mac_nr_args_t {};
 
 class mac_nr final : public mac_interface_phy_nr,
                      public mac_interface_rrc_nr,
@@ -63,6 +62,7 @@ public:
                   const uint32_t t_id,
                   const uint32_t f_id,
                   const uint32_t ul_carrier_id);
+  bool sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx);
 
   /// Stack interface
   void timer_expired(uint32_t timer_id);
@@ -92,10 +92,6 @@ public:
 
   static bool is_in_window(uint32_t tti, int* start, int* len);
 
-  // PHY Interface
-  void prach_sent(const uint32_t tti);
-  void tb_decoded_ok(const uint8_t cc_idx, const uint32_t tti);
-
 private:
   void write_pcap(const uint32_t cc_idx, mac_nr_grant_dl_t& grant); // If PCAPs are enabled for this MAC
   void handle_pdu(srsran::unique_byte_buffer_t pdu);
@@ -107,8 +103,8 @@ private:
   bool is_si_opportunity();
   bool is_paging_opportunity();
 
-  bool     has_crnti();
-  bool     is_valid_crnti(const uint16_t crnti);
+  bool has_crnti();
+  bool is_valid_crnti(const uint16_t crnti);
 
   /// Interaction with rest of the stack
   phy_interface_mac_nr*         phy = nullptr;
@@ -135,8 +131,8 @@ private:
 
   /// Tx buffer
   srsran::unique_byte_buffer_t ul_harq_buffer = nullptr; // store PDU generated from MUX
-  srsran::unique_byte_buffer_t rlc_buffer    = nullptr;
-  srsran_softbuffer_tx_t       softbuffer_tx = {}; /// UL HARQ (temporal)
+  srsran::unique_byte_buffer_t rlc_buffer     = nullptr;
+  srsran_softbuffer_tx_t       softbuffer_tx  = {}; /// UL HARQ (temporal)
 
   srsran::task_multiqueue::queue_handle stack_task_dispatch_queue;
 
diff --git a/srsue/hdr/stack/mac_nr/proc_sr_nr.h b/srsue/hdr/stack/mac_nr/proc_sr_nr.h
index 12dee8275..e88bc1165 100644
--- a/srsue/hdr/stack/mac_nr/proc_sr_nr.h
+++ b/srsue/hdr/stack/mac_nr/proc_sr_nr.h
@@ -35,10 +35,9 @@ public:
   int32_t set_config(const srsran::sr_cfg_nr_t& cfg);
   void    reset();
   void    start();
+  bool    sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx);
 
 private:
-  bool need_tx(uint32_t tti);
-
   int  sr_counter    = 0;
   bool is_pending_sr = 0;
 
diff --git a/srsue/hdr/stack/ue_stack_lte.h b/srsue/hdr/stack/ue_stack_lte.h
index c0778aa1f..8ab5b03be 100644
--- a/srsue/hdr/stack/ue_stack_lte.h
+++ b/srsue/hdr/stack/ue_stack_lte.h
@@ -143,6 +143,11 @@ public:
     mac_nr.prach_sent(tti, s_id, t_id, f_id, ul_carrier_id);
   }
 
+  bool sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx) final
+  {
+    return mac_nr.sr_opportunity(tti, sr_id, meas_gap, ul_sch_tx);
+  }
+
   // Interface for GW
   void write_sdu(uint32_t lcid, srsran::unique_byte_buffer_t sdu) final;
 
diff --git a/srsue/hdr/stack/ue_stack_nr.h b/srsue/hdr/stack/ue_stack_nr.h
index 093f6d1cf..84e10467c 100644
--- a/srsue/hdr/stack/ue_stack_nr.h
+++ b/srsue/hdr/stack/ue_stack_nr.h
@@ -89,6 +89,10 @@ public:
   {
     mac->prach_sent(tti, s_id, t_id, f_id, ul_carrier_id);
   }
+  bool sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx)
+  {
+    return mac->sr_opportunity(tti, sr_id, meas_gap, ul_sch_tx);
+  }
 
   // Interface for GW
   void write_sdu(uint32_t lcid, srsran::unique_byte_buffer_t sdu) final;
diff --git a/srsue/src/phy/nr/worker_pool.cc b/srsue/src/phy/nr/worker_pool.cc
index 7bf9c7c3e..606153250 100644
--- a/srsue/src/phy/nr/worker_pool.cc
+++ b/srsue/src/phy/nr/worker_pool.cc
@@ -134,9 +134,15 @@ bool worker_pool::set_config(const srsran::phy_cfg_nr_t& cfg)
   return true;
 }
 
-void worker_pool::sr_send(uint32_t sr_id)
+bool worker_pool::has_valid_sr_resource(uint32_t sr_id)
 {
-  phy_state.set_pending_sr(sr_id);
+  return phy_state.has_valid_sr_resource(sr_id);
 }
+
+void worker_pool::clear_pending_grants()
+{
+  phy_state.clear_pending_grants();
+}
+
 } // namespace nr
 } // namespace srsue
diff --git a/srsue/src/phy/phy.cc b/srsue/src/phy/phy.cc
index b5e3449cc..e7c5454f5 100644
--- a/srsue/src/phy/phy.cc
+++ b/srsue/src/phy/phy.cc
@@ -621,8 +621,14 @@ bool phy::set_config(const srsran::phy_cfg_nr_t& cfg)
   return nr_workers.set_config(cfg);
 }
 
-void phy::sr_send(uint32_t sr_id)
+bool phy::has_valid_sr_resource(uint32_t sr_id)
 {
-  nr_workers.sr_send(sr_id);
+  return nr_workers.has_valid_sr_resource(sr_id);
 }
+
+void phy::clear_pending_grants()
+{
+  nr_workers.clear_pending_grants();
+}
+
 } // namespace srsue
diff --git a/srsue/src/phy/vnf_phy_nr.cc b/srsue/src/phy/vnf_phy_nr.cc
index 81ef31ea3..b19e2ce4d 100644
--- a/srsue/src/phy/vnf_phy_nr.cc
+++ b/srsue/src/phy/vnf_phy_nr.cc
@@ -72,6 +72,11 @@ bool vnf_phy_nr::set_config(const srsran::phy_cfg_nr_t& cfg)
 {
   return false;
 }
-void vnf_phy_nr::sr_send(uint32_t sr_id) {}
+bool vnf_phy_nr::has_valid_sr_resource(uint32_t sr_id)
+{
+  return false;
+}
+
+void vnf_phy_nr::clear_pending_grants() {}
 
 } // namespace srsue
\ No newline at end of file
diff --git a/srsue/src/stack/mac_nr/mac_nr.cc b/srsue/src/stack/mac_nr/mac_nr.cc
index d752af8c0..d2a96bb71 100644
--- a/srsue/src/stack/mac_nr/mac_nr.cc
+++ b/srsue/src/stack/mac_nr/mac_nr.cc
@@ -181,6 +181,11 @@ void mac_nr::prach_sent(const uint32_t tti,
   proc_ra.prach_sent(tti, s_id, t_id, f_id, ul_carrier_id);
 }
 
+bool mac_nr::sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx)
+{
+  return proc_sr.sr_opportunity(tti, sr_id, meas_gap, ul_sch_tx);
+}
+
 // This function handles all PCAP writing for a decoded DL TB
 void mac_nr::write_pcap(const uint32_t cc_idx, mac_nr_grant_dl_t& grant)
 {
diff --git a/srsue/src/stack/mac_nr/proc_sr_nr.cc b/srsue/src/stack/mac_nr/proc_sr_nr.cc
index e40e1a8ac..7a1f8921f 100644
--- a/srsue/src/stack/mac_nr/proc_sr_nr.cc
+++ b/srsue/src/stack/mac_nr/proc_sr_nr.cc
@@ -35,19 +35,6 @@ void proc_sr_nr::reset()
   is_pending_sr = false;
 }
 
-bool proc_sr_nr::need_tx(uint32_t tti)
-{
-  int last_tx_tti = 0; // FIXME: phy->sr_last_tx_tti();
-  logger.debug("SR:    need_tx(): last_tx_tti=%d, tti=%d", last_tx_tti, tti);
-  if (last_tx_tti >= 0) {
-    // TODO: implement prohibit timer
-    if (TTI_SUB(last_tx_tti, tti) >= 8) {
-      return true;
-    }
-  }
-  return false;
-}
-
 int32_t proc_sr_nr::set_config(const srsran::sr_cfg_nr_t& cfg_)
 {
   // disable by default
@@ -80,38 +67,81 @@ int32_t proc_sr_nr::set_config(const srsran::sr_cfg_nr_t& cfg_)
 
 void proc_sr_nr::step(uint32_t tti)
 {
-  if (initiated) {
-    if (is_pending_sr) {
-      if (cfg.enabled) {
-        if (sr_counter < cfg.item[0].trans_max) {
-          if (sr_counter == 0 || need_tx(tti)) {
-            sr_counter++;
-            logger.info("SR:    Signalling PHY sr_counter=%d", sr_counter);
-            phy->sr_send(0); // @xavierarteaga what is the ID you expect here?
-          }
-        } else {
-          if (need_tx(tti)) {
-            logger.info("SR:    Releasing PUCCH/SRS resources, sr_counter=%d, sr-TransMax=%d",
-                        sr_counter,
-                        cfg.item[0].trans_max);
-            srsran::console("Scheduling request failed: releasing RRC connection...\n");
-            rrc->release_pucch_srs();
-            // TODO:
-            // - clear any configured downlink assignments and uplink grants;
-            // - clear any PUSCH resources for semi-persistent CSI reporting;
-            ra->start_by_mac();
-            reset();
-          }
-        }
-      } else {
-        logger.info("SR:    PUCCH not configured. Starting RA procedure");
-        ra->start_by_mac();
-        reset();
-      }
-    }
+  if (!initiated) {
+    return;
+  }
+
+  // As long as at least one SR is pending, the MAC entity shall for each pending SR:
+  if (!is_pending_sr) {
+    return;
+  }
+
+  // 1> if the MAC entity has no valid PUCCH resource configured for the pending SR:
+  if (!cfg.enabled || not phy->has_valid_sr_resource(0)) {
+    // 2> initiate a Random Access procedure (see clause 5.1) on the SpCell and cancel the pending SR.
+    logger.info("SR:    PUCCH not configured. Starting RA procedure");
+    ra->start_by_mac();
+    reset();
+    return;
+  }
+
+  // Handle
+  if (sr_counter >= cfg.item[0].trans_max) {
+    logger.info(
+        "SR:    Releasing PUCCH/SRS resources, sr_counter=%d, sr-TransMax=%d", sr_counter, cfg.item[0].trans_max);
+    srsran::console("Scheduling request failed: releasing RRC connection...\n");
+    rrc->release_pucch_srs();
+
+    // 4> clear any configured downlink assignments and uplink grants;
+    phy->clear_pending_grants();
+
+    // 4> clear any PUSCH resources for semi-persistent CSI reporting;
+    // ... TODO
+
+    ra->start_by_mac();
+    reset();
   }
 }
 
+bool proc_sr_nr::sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx)
+{
+  // 2> when the MAC entity has an SR transmission occasion on the valid PUCCH resource for SR configured; and
+  if (!initiated || !cfg.enabled || !is_pending_sr) {
+    return false;
+  }
+
+  // 2> if sr-ProhibitTimer is not running at the time of the SR transmission occasion; and
+  // ... TODO
+
+  // 2> if the PUCCH resource for the SR transmission occasion does not overlap with a measurement gap; and
+  if (meas_gap) {
+    return false;
+  }
+
+  // 2> if the PUCCH resource for the SR transmission occasion does not overlap with a UL-SCH resource:
+  if (ul_sch_tx) {
+    return false;
+  }
+
+  // 3> if SR_COUNTER < sr-TransMax:
+  if (sr_counter < cfg.item[0].trans_max) { //
+    // 4> increment SR_COUNTER by 1;
+    sr_counter += 1;
+
+    // 4> start the sr-ProhibitTimer.
+    // ... TODO
+
+    // 4> instruct the physical layer to signal the SR on one valid PUCCH resource for SR;
+    logger.info("SR:    Signalling PHY sr_counter=%d", sr_counter);
+    return true;
+  }
+
+  // 3> else:
+  // step will execute
+
+  return false;
+}
+
 void proc_sr_nr::start()
 {
   if (initiated) {
diff --git a/srsue/test/mac_nr/mac_nr_test.cc b/srsue/test/mac_nr/mac_nr_test.cc
index 55ac58980..de8dc5f63 100644
--- a/srsue/test/mac_nr/mac_nr_test.cc
+++ b/srsue/test/mac_nr/mac_nr_test.cc
@@ -47,7 +47,8 @@ public:
     *preamble_index_                 = preamble_index;
     *preamble_received_target_power_ = preamble_received_target_power;
   }
-  void sr_send(uint32_t sr_id) override {}
+  bool has_valid_sr_resource(uint32_t sr_id) override { return false; }
+  void clear_pending_grants() override {}
 
 private:
   uint32_t prach_occasion                 = 0;
diff --git a/srsue/test/mac_nr/proc_ra_nr_test.cc b/srsue/test/mac_nr/proc_ra_nr_test.cc
index 96b6fd409..9f7bf79fb 100644
--- a/srsue/test/mac_nr/proc_ra_nr_test.cc
+++ b/srsue/test/mac_nr/proc_ra_nr_test.cc
@@ -41,7 +41,8 @@ public:
     *preamble_index_                 = preamble_index;
     *preamble_received_target_power_ = preamble_received_target_power;
   }
-  void sr_send(uint32_t sr_id) override {}
+  bool has_valid_sr_resource(uint32_t sr_id) override { return false; }
+  void clear_pending_grants() override {}
 
 private:
   uint32_t prach_occasion                 = 0;