fix hanging issue, and simplified the handling of minRBG for different CFIs

srsenb/hdr/stack/mac/scheduler_grid.h

@@ -72,7 +72,6 @@ public:
   void new_tti(const tti_params_t& tti_params_);
   bool alloc_dci(alloc_type_t alloc_type, uint32_t aggr_idx, sched_ue* user = nullptr);
   bool set_cfi(uint32_t cfi);
-  void set_max_cfi(uint32_t cfi) { max_user_cfi = cfi; }
 
   // getters
   uint32_t    get_cfi() const { return current_cfix + 1; }
@@ -121,7 +120,7 @@ private:
 
   // tti vars
   const tti_params_t*         tti_params   = nullptr;
-  uint32_t                    current_cfix = 0, max_user_cfi = MAX_CFI;
+  uint32_t                    current_cfix = 0;
   std::vector<alloc_tree_t>   alloc_trees;     ///< List of PDCCH alloc trees, where index is the cfi index
   std::vector<alloc_record_t> dci_record_list; ///< Keeps a record of all the PDCCH allocations done so far
 };

srsenb/hdr/stack/mac/scheduler_ue.h

@@ -133,7 +133,7 @@ public:
 
   uint32_t get_required_prb_ul(uint32_t cc_idx, uint32_t req_bytes);
 
-  rbg_range_t                   get_required_dl_rbgs(uint32_t ue_cc_idx, uint32_t nof_ctrl_symbols);
+  rbg_range_t                   get_required_dl_rbgs(uint32_t ue_cc_idx);
   std::pair<uint32_t, uint32_t> get_requested_dl_bytes(uint32_t ue_cc_idx);
   uint32_t                      get_pending_dl_new_data();
   uint32_t                      get_pending_ul_new_data(uint32_t tti);

srsenb/src/stack/mac/scheduler_grid.cc

@@ -90,7 +90,6 @@ void pdcch_grid_t::new_tti(const tti_params_t& tti_params_)
   }
   dci_record_list.clear();
   current_cfix = cc_cfg->sched_cfg->min_nof_ctrl_symbols - 1;
-  max_user_cfi = cc_cfg->sched_cfg->max_nof_ctrl_symbols;
 }
 
 const sched_dci_cce_t* pdcch_grid_t::get_cce_loc_table(alloc_type_t alloc_type, sched_ue* user, uint32_t cfix) const
@@ -117,16 +116,18 @@ bool pdcch_grid_t::alloc_dci(alloc_type_t alloc_type, uint32_t aggr_idx, sched_u
   // TODO: Make the alloc tree update lazy
   alloc_record_t record{.user = user, .aggr_idx = aggr_idx, .alloc_type = alloc_type};
 
-  // Try to allocate user in PDCCH for given CFI. If it fails, increment CFI
+  // Try to allocate user in PDCCH for given CFI. If it fails, increment CFI.
   uint32_t first_cfi = get_cfi();
-  bool     success   = alloc_dci_record(record, get_cfi() - 1);
-  while (not success and get_cfi() < max_user_cfi) {
-    set_cfi(get_cfi() + 1);
+  bool     success;
+  do {
     success = alloc_dci_record(record, get_cfi() - 1);
-  }
+  } while (not success and get_cfi() < cc_cfg->sched_cfg->max_nof_ctrl_symbols and set_cfi(get_cfi() + 1));
+
   if (not success) {
     // DCI allocation failed. go back to original CFI
-    set_cfi(first_cfi);
+    if (get_cfi() != first_cfi and not set_cfi(first_cfi)) {
+      log_h->error("SCHED: Failed to return back to original PDCCH state\n");
+    }
     return false;
   }
 
@@ -227,7 +228,7 @@ bool pdcch_grid_t::set_cfi(uint32_t cfi)
 {
   if (cfi < cc_cfg->sched_cfg->min_nof_ctrl_symbols or cfi > cc_cfg->sched_cfg->max_nof_ctrl_symbols) {
     srslte::logmap::get("MAC")->error("Invalid CFI value. Defaulting to current CFI.\n");
-    return true;
+    return false;
   }
 
   uint32_t new_cfix = cfi - 1;
@@ -408,22 +409,11 @@ alloc_outcome_t sf_grid_t::alloc_dl_data(sched_ue* user, const rbgmask_t& user_m
 {
   // Check if allocation would cause segmentation
   uint32_t    ue_cc_idx = user->get_cell_index(cc_cfg->enb_cc_idx).second;
-  rbg_range_t r         = user->get_required_dl_rbgs(ue_cc_idx, pdcch_alloc.get_cfi());
+  rbg_range_t r         = user->get_required_dl_rbgs(ue_cc_idx);
   if (r.rbg_min > user_mask.count()) {
     log_h->error("The number of RBGs allocated will force segmentation\n");
     return alloc_outcome_t::NOF_RB_INVALID;
   }
-  // Place an upper bound in CFI if necessary, to avoid segmentation
-  if (pdcch_alloc.get_cfi() < cc_cfg->sched_cfg->max_nof_ctrl_symbols) {
-    for (uint32_t cfi = cc_cfg->sched_cfg->max_nof_ctrl_symbols; cfi >= pdcch_alloc.get_cfi() + 1; --cfi) {
-      r = user->get_required_dl_rbgs(ue_cc_idx, cfi);
-      if (r.rbg_min <= user_mask.count()) {
-        break;
-      }
-      // decrease max CFI
-      pdcch_alloc.set_max_cfi(cfi);
-    }
-  }
 
   srslte_dci_format_t dci_format = user->get_dci_format();
   uint32_t            nof_bits   = srslte_dci_format_sizeof(&cc_cfg->cfg.cell, nullptr, nullptr, dci_format);

srsenb/src/stack/mac/scheduler_metric.cc

@@ -133,7 +133,7 @@ dl_harq_proc* dl_metric_rr::allocate_user(sched_ue* user)
   h = user->get_empty_dl_harq(tti_dl, cell_idx);
   if (h != nullptr) {
     // Allocate resources based on pending data
-    rbg_range_t req_rbgs = user->get_required_dl_rbgs(cell_idx, tti_alloc->get_nof_ctrl_symbols());
+    rbg_range_t req_rbgs = user->get_required_dl_rbgs(cell_idx);
     if (req_rbgs.rbg_min > 0) {
       rbgmask_t newtx_mask(tti_alloc->get_dl_mask().size());
       if (find_allocation(req_rbgs.rbg_min, req_rbgs.rbg_max, &newtx_mask)) {

srsenb/src/stack/mac/scheduler_ue.cc

@@ -813,14 +813,20 @@ uint32_t sched_ue::get_pending_dl_new_data_total()
   return req_bytes;
 }
 
-rbg_range_t sched_ue::get_required_dl_rbgs(uint32_t ue_cc_idx, uint32_t nof_ctrl_symbols)
+/**
+ * Compute the range of RBGs that avoids segmentation of TM and MAC subheader data. Always computed for highest CFI
+ * @param ue_cc_idx carrier of the UE
+ * @return range of number of RBGs that a UE can allocate in a given subframe
+ */
+rbg_range_t sched_ue::get_required_dl_rbgs(uint32_t ue_cc_idx)
 {
   std::pair<uint32_t, uint32_t> req_bytes = get_requested_dl_bytes(ue_cc_idx);
   if (req_bytes.first == 0 and req_bytes.second == 0) {
     return {0, 0};
   }
-  const auto* cellparams   = carriers[ue_cc_idx].get_cell_cfg();
-  int         pending_prbs = carriers[ue_cc_idx].get_required_prb_dl(req_bytes.first, nof_ctrl_symbols);
+  const auto* cellparams = carriers[ue_cc_idx].get_cell_cfg();
+  int         pending_prbs =
+      carriers[ue_cc_idx].get_required_prb_dl(req_bytes.first, cellparams->sched_cfg->max_nof_ctrl_symbols);
   if (pending_prbs < 0) {
     // Cannot fit allocation in given PRBs
     log_h->error("SCHED: DL CQI=%d does now allow fitting %d non-segmentable DL tx bytes into the cell bandwidth. "
@@ -830,8 +836,8 @@ rbg_range_t sched_ue::get_required_dl_rbgs(uint32_t ue_cc_idx, uint32_t nof_ctrl
     return {cellparams->nof_prb(), cellparams->nof_prb()};
   }
   uint32_t min_pending_rbg = cellparams->prb_to_rbg(pending_prbs);
-  pending_prbs             = carriers[ue_cc_idx].get_required_prb_dl(req_bytes.second, nof_ctrl_symbols);
-  pending_prbs             = (pending_prbs < 0) ? cellparams->nof_prb() : pending_prbs;
+  pending_prbs = carriers[ue_cc_idx].get_required_prb_dl(req_bytes.second, cellparams->sched_cfg->max_nof_ctrl_symbols);
+  pending_prbs = (pending_prbs < 0) ? cellparams->nof_prb() : pending_prbs;
   uint32_t max_pending_rbg = cellparams->prb_to_rbg(pending_prbs);
   return {min_pending_rbg, max_pending_rbg};
 }