From b4f46144fe376f75f61bf77d03efbb6f83660c45 Mon Sep 17 00:00:00 2001
From: Sakthivel Velumani <velumani@eurecom.fr>
Date: Fri, 28 Feb 2020 17:30:21 +0100
Subject: [PATCH] Fixed bugs in frame sync for UE UE is a bit more stable now

---
 executables/nr-ue.c                            | 9 ++++++---
 openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c | 8 +++++++-
 openair1/PHY/defs_nr_UE.h                      | 1 +
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/executables/nr-ue.c b/executables/nr-ue.c
index 8b8b8be6eb..212de80f06 100644
--- a/executables/nr-ue.c
+++ b/executables/nr-ue.c
@@ -666,6 +666,8 @@ void *UE_thread(void *arg) {
   int thread_idx=0;
   notifiedFIFO_t freeBlocks;
   initNotifiedFIFO_nothreadSafe(&freeBlocks);
+  NR_UE_MAC_INST_t *mac = get_mac_inst(0);
+
 
   for (int i=0; i<RX_NB_TH+1; i++)  // RX_NB_TH working + 1 we are making to be pushed
     pushNotifiedFIFO_nothreadSafe(&freeBlocks,
@@ -683,11 +685,12 @@ void *UE_thread(void *arg) {
         syncRunning=false;
         syncData_t *tmp=(syncData_t *)NotifiedFifoData(res);
         // shift the frame index with all the frames we trashed meanwhile we perform the synch search
-        decoded_frame_rx=(tmp->proc.decoded_frame_rx+trashed_frames) % MAX_FRAME_NUMBER;
+        decoded_frame_rx=((((mac->mib->systemFrameNumber.buf[0] >> mac->mib->systemFrameNumber.bits_unused)<<4) | tmp->proc.decoded_frame_rx) +
+                         (!UE->init_sync_frame) + trashed_frames) % MAX_FRAME_NUMBER;
         delNotifiedFIFO_elt(res);
       } else {
         readFrame(UE, &timestamp, true);
-        trashed_frames++;
+        trashed_frames+=2;
         continue;
       }
     }
@@ -722,7 +725,7 @@ void *UE_thread(void *arg) {
       // and we shifted above to the first slot of next frame
       decoded_frame_rx++;
       // we do ++ first in the regular processing, so it will be begin of frame;
-      absolute_slot=decoded_frame_rx*nb_slot_frame + nb_slot_frame -1;
+      absolute_slot=decoded_frame_rx*nb_slot_frame -1;
       continue;
     }
 
diff --git a/openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c b/openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c
index bc687a917f..61748a8e56 100644
--- a/openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c
+++ b/openair1/PHY/NR_UE_TRANSPORT/nr_initial_sync.c
@@ -303,7 +303,13 @@ int nr_initial_sync(UE_nr_rxtx_proc_t *proc, PHY_VARS_NR_UE *ue, runmode_t mode,
         // sync at symbol ue->symbol_offset
         // computing the offset wrt the beginning of the frame
         sync_pos_frame = (fp->ofdm_symbol_size + fp->nb_prefix_samples0)+((ue->symbol_offset)-1)*(fp->ofdm_symbol_size + fp->nb_prefix_samples);
-        ue->rx_offset = ue->ssb_offset - sync_pos_frame;
+
+        if (ue->ssb_offset < sync_pos_frame)
+          ue->rx_offset = fp->samples_per_frame - sync_pos_frame + ue->ssb_offset;
+        else
+          ue->rx_offset = ue->ssb_offset - sync_pos_frame;
+
+        ue->init_sync_frame = is;
       }   
 
       nr_gold_pdcch(ue,0, 2);
diff --git a/openair1/PHY/defs_nr_UE.h b/openair1/PHY/defs_nr_UE.h
index 1ad0c7529e..4774bd4402 100644
--- a/openair1/PHY/defs_nr_UE.h
+++ b/openair1/PHY/defs_nr_UE.h
@@ -1012,6 +1012,7 @@ typedef struct {
   //  uint8_t               prach_timer;
   uint8_t               decode_SIB;
   uint8_t               decode_MIB;
+  uint8_t               init_sync_frame;
   /// temporary offset during cell search prior to MIB decoding
   int              ssb_offset;
   uint16_t	   symbol_offset; // offset in terms of symbols for detected ssb in sync
-- 
2.26.2