From ad646f436c446227f58c5c428e112969eb0ff9ac Mon Sep 17 00:00:00 2001
From: Ismael Gomez <ismagom@gmail.com>
Date: Mon, 20 Sep 2021 19:18:32 +0200
Subject: [PATCH] Ignore PDSCH during cell selection

---
 srsue/hdr/phy/phy_common.h     | 2 ++
 srsue/src/phy/lte/cc_worker.cc | 7 ++++++-
 srsue/src/phy/phy.cc           | 8 ++++++++
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/srsue/hdr/phy/phy_common.h b/srsue/hdr/phy/phy_common.h
index 18cc46b7c..ede7de462 100644
--- a/srsue/hdr/phy/phy_common.h
+++ b/srsue/hdr/phy/phy_common.h
@@ -56,6 +56,8 @@ public:
 
   srsran::phy_cfg_mbsfn_t mbsfn_config = {};
 
+  std::atomic<bool> cell_is_selecting = {false};
+
   // Secondary serving cell states
   scell::state cell_state;
 
diff --git a/srsue/src/phy/lte/cc_worker.cc b/srsue/src/phy/lte/cc_worker.cc
index 9fa2e921e..bf2352d34 100644
--- a/srsue/src/phy/lte/cc_worker.cc
+++ b/srsue/src/phy/lte/cc_worker.cc
@@ -280,7 +280,12 @@ bool cc_worker::work_dl_regular()
     // Decode PDSCH
     decode_pdsch(ack_resource, &dl_action, dl_ack);
 
-    // Informs Stack about the decoding status
+    // Informs Stack about the decoding status, send NACK if cell is in process of re-selection
+    if (phy->cell_is_selecting) {
+      for (uint32_t i = 0; i < SRSRAN_MAX_CODEWORDS; i++) {
+        dl_ack[i] = false;
+      }
+    }
     phy->stack->tb_decoded(cc_idx, mac_grant, dl_ack);
   }
 
diff --git a/srsue/src/phy/phy.cc b/srsue/src/phy/phy.cc
index c6fb51f3a..94672b253 100644
--- a/srsue/src/phy/phy.cc
+++ b/srsue/src/phy/phy.cc
@@ -306,6 +306,10 @@ bool phy::cell_select(phy_cell_t cell)
   if (sfsync.cell_select_init(cell)) {
     // Update PCI before starting the background command to make sure PRACH gets the updated value
     selected_cell.id = cell.pci;
+
+    // Indicate workers that cell selection is in progress
+    common.cell_is_selecting = true;
+
     cmd_worker_cell.add_cmd([this, cell]() {
       // Wait SYNC transitions to IDLE
       sfsync.wait_idle();
@@ -320,6 +324,10 @@ bool phy::cell_select(phy_cell_t cell)
         selected_cell = sync_cell;
       }
       stack->cell_select_complete(ret);
+
+      // Indicate workers that cell selection has finished
+      common.cell_is_selecting = false;
+
     });
     return true;
   } else {