avoid allocating DL harqs when respective acks are still pending, when there is a reordering of ttis in the phy

srsenb/hdr/stack/mac/sched_harq.h

@@ -73,6 +73,7 @@ public:
   int       set_ack(uint32_t tb_idx, bool ack);
   rbgmask_t get_rbgmask() const;
   bool      has_pending_retx(uint32_t tb_idx, tti_point tti_tx_dl) const;
+  bool      has_pending_retx(tti_point tti_tx_dl) const;
   int       get_tbs(uint32_t tb_idx) const;
   uint32_t  get_n_cce() const;
   void      reset_pending_data();
@@ -111,6 +112,7 @@ public:
 
   harq_entity(size_t nof_dl_harqs, size_t nof_ul_harqs);
   void reset();
+  void new_tti(tti_point tti_rx);
 
   size_t                           nof_dl_harqs() const { return dl_harqs.size(); }
   size_t                           nof_ul_harqs() const { return ul_harqs.size(); }
@@ -155,6 +157,7 @@ private:
   dl_harq_proc* get_oldest_dl_harq(tti_point tti_tx_dl);
 
   srslte::log_ref                            log_h;
+  std::array<tti_point, SRSLTE_FDD_NOF_HARQ> last_ttis;
 
   std::vector<dl_harq_proc> dl_harqs;
   std::vector<ul_harq_proc> ul_harqs;

srsenb/hdr/stack/mac/sched_ue.h

@@ -258,6 +258,7 @@ private:
   bool phy_config_dedicated_enabled = false;
 
   tti_point                current_tti;
+  std::array<tti_point, 4> last_ttis;
   std::vector<cc_sched_ue> carriers; ///< map of UE CellIndex to carrier configuration
   std::vector<int>         enb_ue_cc_idx_map;
 };

srsenb/src/stack/mac/sched_harq.cc

@@ -206,6 +206,11 @@ bool dl_harq_proc::has_pending_retx(uint32_t tb_idx, tti_point tti_tx_dl) const
   return (tti_tx_dl >= to_tx_dl_ack(tti)) and has_pending_retx_common(tb_idx);
 }
 
+bool dl_harq_proc::has_pending_retx(tti_point tti_tx_dl) const
+{
+  return has_pending_retx(0, tti_tx_dl) or has_pending_retx(1, tti_tx_dl);
+}
+
 int dl_harq_proc::get_tbs(uint32_t tb_idx) const
 {
   return last_tbs[tb_idx];
@@ -314,6 +319,11 @@ void harq_entity::reset()
   }
 }
 
+void harq_entity::new_tti(tti_point tti_rx)
+{
+  last_ttis[tti_rx.to_uint() % last_ttis.size()] = tti_rx;
+}
+
 dl_harq_proc* harq_entity::get_empty_dl_harq(tti_point tti_tx_dl)
 {
   if (not is_async) {
@@ -382,7 +392,8 @@ dl_harq_proc* harq_entity::get_oldest_dl_harq(tti_point tti_tx_dl)
   int      oldest_idx = -1;
   uint32_t oldest_tti = 0;
   for (const dl_harq_proc& h : dl_harqs) {
-    if (h.has_pending_retx(0, tti_tx_dl) or h.has_pending_retx(1, tti_tx_dl)) {
+    tti_point ack_tti_rx = h.get_tti() + FDD_HARQ_DELAY_DL_MS;
+    if (h.has_pending_retx(tti_tx_dl) and (last_ttis[ack_tti_rx.to_uint() % last_ttis.size()] == ack_tti_rx)) {
       uint32_t x = tti_tx_dl - h.get_tti();
       if (x > oldest_tti) {
         oldest_idx = h.get_id();

srsenb/src/stack/mac/sched_ue.cc

@@ -227,6 +227,9 @@ void sched_ue::new_subframe(tti_point tti_rx, uint32_t enb_cc_idx)
   if (current_tti != tti_rx) {
     current_tti = tti_rx;
     lch_handler.new_tti();
+    for (auto& cc : carriers) {
+      cc.harq_ent.new_tti(tti_rx);
+    }
   }
   int ue_cc_idx = enb_ue_cc_idx_map[enb_cc_idx];
   if (ue_cc_idx >= 0) {
@@ -1501,7 +1504,7 @@ int cc_sched_ue::get_required_prb_dl(uint32_t req_bytes, uint32_t nof_ctrl_symbo
 {
   auto compute_tbs_approx = [this, nof_ctrl_symbols](uint32_t nof_prb) {
     uint32_t nof_re = srslte_ra_dl_approx_nof_re(&cell_params->cfg.cell, nof_prb, nof_ctrl_symbols);
-    int      mcs, tbs;
+    int      mcs;
     if (fixed_mcs_dl < 0 or not dl_cqi_rx) {
       return alloc_tbs_dl(nof_prb, nof_re, 0, &mcs);
     }
@@ -1523,7 +1526,7 @@ uint32_t cc_sched_ue::get_required_prb_ul(uint32_t req_bytes)
   auto compute_tbs_approx = [this](uint32_t nof_prb) {
     const uint32_t N_srs  = 0;
     uint32_t       nof_re = (2 * (SRSLTE_CP_NSYMB(cell_params->cfg.cell.cp) - 1) - N_srs) * nof_prb * SRSLTE_NRE;
-    int            mcs, tbs;
+    int            mcs;
     if (fixed_mcs_ul < 0) {
       return alloc_tbs_ul(nof_prb, nof_re, 0, &mcs);
     }