From c249ca0bd826204d4d82b532a2a5fc3cc29294fb Mon Sep 17 00:00:00 2001
From: francescomani <francesco.mani@eurecom.fr>
Date: Thu, 24 Jun 2021 12:22:03 +0200
Subject: [PATCH] fix for empty mib at beginning of execution

---
 openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_bch.c | 6 +++++-
 openair2/LAYER2/NR_MAC_gNB/main.c              | 2 ++
 openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h        | 1 +
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_bch.c b/openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_bch.c
index f93ad92a13..29a31e72b9 100644
--- a/openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_bch.c
+++ b/openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_bch.c
@@ -158,10 +158,14 @@ void schedule_nr_mib(module_id_t module_idP, frame_t frameP, sub_frame_t slotP)
     dl_req = &dl_tti_request->dl_tti_request_body;
 
     // get MIB every 8 frames
-    if((slotP == 0) && (frameP & 7) == 0) {
+    if(((slotP == 0) && (frameP & 7) == 0) ||
+       gNB->first_MIB) {
 
       mib_sdu_length = mac_rrc_nr_data_req(module_idP, CC_id, frameP, MIBCH, 0, 1, &cc->MIB_pdu.payload[0]);
 
+      // flag to avoid sending an empty MIB in the first frames of execution since gNB doesn't get at the beginning in frame 0 slot 0
+      gNB->first_MIB = false;
+
       LOG_D(MAC,
             "[gNB %d] Frame %d : MIB->BCH  CC_id %d, Received %d bytes\n",
             module_idP,
diff --git a/openair2/LAYER2/NR_MAC_gNB/main.c b/openair2/LAYER2/NR_MAC_gNB/main.c
index 60b0cac215..fbb5cd578d 100644
--- a/openair2/LAYER2/NR_MAC_gNB/main.c
+++ b/openair2/LAYER2/NR_MAC_gNB/main.c
@@ -81,6 +81,8 @@ void mac_top_init_gNB(void)
         
       RC.nrmac[i]->ul_handle = 0;
 
+      RC.nrmac[i]->first_MIB = true;
+
       if (get_softmodem_params()->phy_test) {
         RC.nrmac[i]->pre_processor_dl = nr_preprocessor_phytest;
         RC.nrmac[i]->pre_processor_ul = nr_ul_preprocessor_phytest;
diff --git a/openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h b/openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h
index c1ec27580f..a7c2b9a64c 100644
--- a/openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h
+++ b/openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h
@@ -736,6 +736,7 @@ typedef struct gNB_MAC_INST_s {
   NR_CellGroupConfig_t *secondaryCellGroupCommon;
   NR_Type0_PDCCH_CSS_config_t type0_PDCCH_CSS_config[64];
 
+  bool first_MIB;
 } gNB_MAC_INST;
 
 #endif /*__LAYER2_NR_MAC_GNB_H__ */