diff --git a/executables/nr-ue.c b/executables/nr-ue.c
index a1490c104f..1ceb49e0d7 100644
--- a/executables/nr-ue.c
+++ b/executables/nr-ue.c
@@ -533,20 +533,23 @@ static void RU_write(nr_rxtx_thread_data_t *rxtxD) {
 
 }
 
-void processSlotTX(void *arg) {
-
+void processSlotTX(void *arg)
+{
   nr_rxtx_thread_data_t *rxtxD = (nr_rxtx_thread_data_t *) arg;
   const UE_nr_rxtx_proc_t *proc = &rxtxD->proc;
   PHY_VARS_NR_UE    *UE   = rxtxD->UE;
   nr_phy_data_tx_t phy_data = {0};
 
+  if (UE->if_inst)
+    UE->if_inst->slot_indication(UE->Mod_id);
+
   LOG_D(PHY,
         "SlotTx %d.%d => slot type %d, wait: %d \n",
         proc->frame_tx,
         proc->nr_slot_tx,
         proc->tx_slot_type,
         rxtxD->tx_wait_for_dlsch);
-  if (proc->tx_slot_type == NR_UPLINK_SLOT || proc->tx_slot_type == NR_MIXED_SLOT){
+  if (proc->tx_slot_type == NR_UPLINK_SLOT || proc->tx_slot_type == NR_MIXED_SLOT) {
     if (rxtxD->tx_wait_for_dlsch)
       LOG_D(PHY, "enter wait for tx, slot %d, nb events to wait %d; ", proc->nr_slot_tx, rxtxD->tx_wait_for_dlsch);
     // wait for rx slots to send indication (if any) that DLSCH decoding is finished
diff --git a/openair2/LAYER2/NR_MAC_UE/mac_defs.h b/openair2/LAYER2/NR_MAC_UE/mac_defs.h
index f5ec77d8af..b5912d35dd 100644
--- a/openair2/LAYER2/NR_MAC_UE/mac_defs.h
+++ b/openair2/LAYER2/NR_MAC_UE/mac_defs.h
@@ -322,10 +322,8 @@ typedef struct {
   /// Msg3 buffer
   uint8_t *Msg3_buffer;
 
-  /// Random-access Contention Resolution Timer active flag
-  uint8_t RA_contention_resolution_timer_active;
-  int RA_contention_resolution_target_frame;
-  int RA_contention_resolution_target_slot;
+  /// Random-access Contention Resolution Timer
+  NR_timer_t contention_resolution_timer;
   /// Transmitted UE Contention Resolution Identifier
   uint8_t cont_res_id[6];
 
diff --git a/openair2/LAYER2/NR_MAC_UE/mac_proto.h b/openair2/LAYER2/NR_MAC_UE/mac_proto.h
index 512c6eb483..c7ff78a34d 100644
--- a/openair2/LAYER2/NR_MAC_UE/mac_proto.h
+++ b/openair2/LAYER2/NR_MAC_UE/mac_proto.h
@@ -150,6 +150,7 @@
 void nr_ue_init_mac(NR_UE_MAC_INST_t *mac);
 
 void send_srb0_rrc(int ue_id, const uint8_t *sdu, sdu_size_t sdu_len, void *data);
+void update_mac_timers(NR_UE_MAC_INST_t *mac);
 
 /**\brief apply default configuration values in nr_mac instance
    \param mac           mac instance */
diff --git a/openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c b/openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c
index fa4e07ca5e..738b8ff7c4 100644
--- a/openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c
+++ b/openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c
@@ -592,22 +592,14 @@ void nr_Msg3_transmitted(NR_UE_MAC_INST_t *mac, uint8_t CC_id, frame_t frameP, s
   RA_config_t *ra = &mac->ra;
   NR_RACH_ConfigCommon_t *nr_rach_ConfigCommon = mac->current_UL_BWP->rach_ConfigCommon;
   long mu = mac->current_UL_BWP->scs;
-  int subframes_per_slot = nr_slots_per_frame[mu]/10;
+  int subframes_per_slot = nr_slots_per_frame[mu] / 10;
 
-  // start contention resolution timer (cnt in slots)
-  int RA_contention_resolution_timer_subframes = (nr_rach_ConfigCommon->ra_ContentionResolutionTimer + 1)<<3;
+  // start contention resolution timer
+  int RA_contention_resolution_timer_subframes = (nr_rach_ConfigCommon->ra_ContentionResolutionTimer + 1) << 3;
+  // timer step 1 slot and timer target given by ra_ContentionResolutionTimer
+  nr_timer_setup(&ra->contention_resolution_timer, RA_contention_resolution_timer_subframes * subframes_per_slot, 1);
+  nr_timer_start(&ra->contention_resolution_timer);
 
-  ra->RA_contention_resolution_target_frame = (frameP + (RA_contention_resolution_timer_subframes/10)) % MAX_FRAME_NUMBER;
-  ra->RA_contention_resolution_target_slot = (slotP + (RA_contention_resolution_timer_subframes * subframes_per_slot)) % nr_slots_per_frame[mu];
-
-  LOG_D(MAC,"[UE %d] CB-RA: contention resolution timer set in frame.slot %d.%d and expiring in %d.%d\n",
-        mac->ue_id,
-        frameP,
-        slotP,
-        ra->RA_contention_resolution_target_frame,
-        ra->RA_contention_resolution_target_slot);
-
-  ra->RA_contention_resolution_timer_active = 1;
   ra->ra_state = WAIT_CONTENTION_RESOLUTION;
 }
 
@@ -770,7 +762,7 @@ void nr_ue_get_rach(NR_UE_MAC_INST_t *mac, int CC_id, frame_t frame, uint8_t gNB
     }
   }
 
-  if (ra->RA_contention_resolution_timer_active) {
+  if (is_nr_timer_active(ra->contention_resolution_timer)) {
     nr_ue_contention_resolution(mac, CC_id, frame, nr_slot_tx, prach_resources);
   }
 }
@@ -826,16 +818,12 @@ void nr_ue_contention_resolution(NR_UE_MAC_INST_t *mac, int cc_id, frame_t frame
 {
   RA_config_t *ra = &mac->ra;
 
-  if (ra->RA_contention_resolution_timer_active == 1) {
-    if (frame >= ra->RA_contention_resolution_target_frame &&
-      slot >= ra->RA_contention_resolution_target_slot) {
-      ra->t_crnti = 0;
-      ra->RA_active = 0;
-      ra->RA_contention_resolution_timer_active = 0;
-      // Signal PHY to quit RA procedure
-      LOG_E(MAC, "[UE %d] CB-RA: Contention resolution timer has expired, RA procedure has failed...\n", mac->ue_id);
-      nr_ra_failed(mac, cc_id, prach_resources, frame, slot);
-    }
+  if (nr_timer_expired(ra->contention_resolution_timer)) {
+    ra->t_crnti = 0;
+    nr_timer_stop(&ra->contention_resolution_timer);
+    // Signal PHY to quit RA procedure
+    LOG_E(MAC, "[UE %d] CB-RA: Contention resolution timer has expired, RA procedure has failed...\n", mac->ue_id);
+    nr_ra_failed(mac, cc_id, prach_resources, frame, slot);
   }
 }
 
@@ -852,7 +840,7 @@ void nr_ra_succeeded(NR_UE_MAC_INST_t *mac, const uint8_t gNB_index, const frame
     ra->RA_window_cnt = -1;
   } else {
     LOG_A(MAC, "[UE %d][%d.%d][RAPROC] RA procedure succeeded. CB-RA: Contention Resolution is successful.\n", mac->ue_id, frame, slot);
-    ra->RA_contention_resolution_timer_active = 0;
+    nr_timer_stop(&ra->contention_resolution_timer);
     mac->crnti = ra->t_crnti;
     ra->t_crnti = 0;
     LOG_D(MAC, "[UE %d][%d.%d] CB-RA: cleared contention resolution timer...\n", mac->ue_id, frame, slot);
diff --git a/openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c b/openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
index d135225c1e..6ac8cca886 100644
--- a/openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
+++ b/openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c
@@ -90,6 +90,11 @@ fapi_nr_ul_config_request_pdu_t *lockGet_ul_config(NR_UE_MAC_INST_t *mac, frame_
   return pdu;
 }
 
+void update_mac_timers(NR_UE_MAC_INST_t *mac)
+{
+  nr_timer_tick(&mac->ra.contention_resolution_timer);
+}
+
 void remove_ul_config_last_item(fapi_nr_ul_config_request_pdu_t *pdu)
 {
   pdu->privateNBpdus--;
diff --git a/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c b/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c
index 668cc7d52b..7f9f5aa55e 100644
--- a/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c
+++ b/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c
@@ -1278,6 +1278,14 @@ int nr_ue_dl_indication(nr_downlink_indication_t *dl_info)
   return ret2;
 }
 
+void nr_ue_slot_indication(uint8_t mod_id)
+{
+  pthread_mutex_lock(&mac_IF_mutex);
+  NR_UE_MAC_INST_t *mac = get_mac_inst(mod_id);
+  update_mac_timers(mac);
+  pthread_mutex_unlock(&mac_IF_mutex);
+}
+
 nr_ue_if_module_t *nr_ue_if_module_init(uint32_t module_id)
 {
   if (nr_ue_if_module_inst[module_id] == NULL) {
@@ -1295,6 +1303,7 @@ nr_ue_if_module_t *nr_ue_if_module_init(uint32_t module_id)
       nr_ue_if_module_inst[module_id]->scheduled_response = nr_ue_scheduled_response;
     nr_ue_if_module_inst[module_id]->dl_indication = nr_ue_dl_indication;
     nr_ue_if_module_inst[module_id]->ul_indication = nr_ue_ul_indication;
+    nr_ue_if_module_inst[module_id]->slot_indication = nr_ue_slot_indication;
   }
   pthread_mutex_init(&mac_IF_mutex, NULL);
 
diff --git a/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.h b/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.h
index c8648d4855..9acb4785fd 100644
--- a/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.h
+++ b/openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.h
@@ -245,6 +245,7 @@ typedef int (nr_ue_dl_indication_f)(nr_downlink_indication_t *dl_info);
  */
 typedef int (nr_ue_ul_indication_f)(nr_uplink_indication_t *ul_info);
 
+typedef void (nr_ue_slot_indication_f)(uint8_t mod_id);
 
 /*
  * Generic type of an application-defined callback to return various
@@ -263,6 +264,7 @@ typedef struct nr_ue_if_module_s {
   nr_ue_dl_indication_f      *dl_indication;
   nr_ue_ul_indication_f      *ul_indication;
   nr_ue_sl_indication_f      *sl_indication;
+  nr_ue_slot_indication_f    *slot_indication;
   uint32_t cc_mask;
   uint32_t current_frame;
   uint32_t current_slot;