sched, feature enhancement, bugfix - allow RAR DL grants with variable PRB size

Some bug fixes had to be solved:
- the cfi cannot be dynamic once we set a SIB/paging/RAR allocation. This is too avoid effective coderate to exceed its maximum
- the previous bugfix required adding the feature to cancel the last PDCCH+PDSCH allocation

srsenb/hdr/stack/mac/sched_carrier.h

@@ -115,6 +115,8 @@ public:
   void reset();
 
 private:
+  alloc_outcome_t allocate_pending_rar(sf_sched* tti_sched, const pending_rar_t& rar, uint32_t& nof_grants_alloc);
+
   // args
   srslog::basic_logger&      logger;
   const sched_cell_params_t* cc_cfg = nullptr;

srsenb/hdr/stack/mac/sched_common.h

@@ -106,6 +106,10 @@ struct prb_interval : public srslte::interval<uint32_t> {
 
 /// Type of Allocation stored in PDSCH/PUSCH
 enum class alloc_type_t { DL_BC, DL_PCCH, DL_RAR, DL_DATA, UL_DATA };
+inline bool is_dl_ctrl_alloc(alloc_type_t a)
+{
+  return a == alloc_type_t::DL_BC or a == alloc_type_t::DL_PCCH or a == alloc_type_t::DL_RAR;
+}
 
 } // namespace srsenb
 

srsenb/hdr/stack/mac/sched_grid.h

@@ -37,7 +37,8 @@ struct alloc_outcome_t {
     NO_DATA,
     INVALID_PRBMASK,
     INVALID_CARRIER,
-    INVALID_CODERATE
+    CODERATE_TOO_HIGH,
+    NOF_ALLOCS_LIMIT
   };
   result_enum result = ERROR;
   alloc_outcome_t()  = default;
@@ -101,10 +102,11 @@ public:
 
   void            init(const sched_cell_params_t& cell_params_);
   void            new_tti(tti_point tti_rx);
-  dl_ctrl_alloc_t alloc_dl_ctrl(uint32_t aggr_lvl, alloc_type_t alloc_type);
   alloc_outcome_t alloc_dl_ctrl(uint32_t aggr_lvl, rbg_interval rbg_range, alloc_type_t alloc_type);
   alloc_outcome_t alloc_dl_data(sched_ue* user, const rbgmask_t& user_mask, bool has_pusch_grant);
   bool            reserve_dl_rbgs(uint32_t start_rbg, uint32_t end_rbg);
+  void            rem_last_alloc_dl(rbg_interval rbgs);
+
   alloc_outcome_t alloc_ul_data(sched_ue* user, prb_interval alloc, bool needs_pdcch, bool strict = true);
   alloc_outcome_t reserve_ul_prbs(const prbmask_t& prbmask, bool strict);
   alloc_outcome_t reserve_ul_prbs(prb_interval alloc, bool strict);
@@ -128,7 +130,6 @@ private:
   const sched_cell_params_t* cc_cfg = nullptr;
   srslog::basic_logger&      logger;
   uint32_t                   nof_rbgs  = 0;
-  uint32_t                   si_n_rbg = 0, rar_n_rbg = 0;
   uint32_t                   pucch_nrb = 0;
   prbmask_t                  pucch_mask;
 
@@ -137,7 +138,6 @@ private:
 
   // internal state
   tti_point tti_rx;
-  uint32_t  avail_rbg = 0;
   rbgmask_t dl_mask = {};
   prbmask_t ul_mask = {};
 };
@@ -157,8 +157,6 @@ public:
   struct rar_alloc_t {
     sf_sched::ctrl_alloc_t          alloc_data;
     sched_interface::dl_sched_rar_t rar_grant;
-    rar_alloc_t(const sf_sched::ctrl_alloc_t& c, const sched_interface::dl_sched_rar_t& r) : alloc_data(c), rar_grant(r)
-    {}
   };
   struct bc_alloc_t : public ctrl_alloc_t {
     sched_interface::dl_sched_bc_t bc_grant;
@@ -198,7 +196,7 @@ public:
   // DL alloc methods
   alloc_outcome_t alloc_sib(uint32_t aggr_lvl, uint32_t sib_idx, uint32_t sib_ntx, rbg_interval rbgs);
   alloc_outcome_t alloc_paging(uint32_t aggr_lvl, uint32_t paging_payload, rbg_interval rbgs);
-  std::pair<alloc_outcome_t, uint32_t> alloc_rar(uint32_t aggr_lvl, const pending_rar_t& rar_grant);
+  alloc_outcome_t alloc_rar(uint32_t aggr_lvl, const pending_rar_t& rar_grant, rbg_interval rbgs, uint32_t nof_grants);
   bool reserve_dl_rbgs(uint32_t rbg_start, uint32_t rbg_end) { return tti_alloc.reserve_dl_rbgs(rbg_start, rbg_end); }
   const std::vector<rar_alloc_t>& get_allocated_rars() const { return rar_allocs; }
 
@@ -228,7 +226,6 @@ public:
   const sched_cell_params_t* get_cc_cfg() const { return cc_cfg; }
 
 private:
-  ctrl_code_t alloc_dl_ctrl(uint32_t aggr_lvl, uint32_t tbs_bytes, uint16_t rnti);
   void set_bc_sched_result(const sf_cch_allocator::alloc_result_t& dci_result,
                            sched_interface::dl_sched_res_t*        dl_result);
   void set_rar_sched_result(const sf_cch_allocator::alloc_result_t& dci_result,

srsenb/hdr/stack/mac/sched_phy_ch/sf_cch_allocator.h

@@ -48,6 +48,8 @@ public:
    */
   bool alloc_dci(alloc_type_t alloc_type, uint32_t aggr_idx, sched_ue* user = nullptr, bool has_pusch_grant = false);
 
+  void rem_last_dci();
+
   // getters
   uint32_t    get_cfi() const { return current_cfix + 1; }
   void        get_allocs(alloc_result_t* vec = nullptr, pdcch_mask_t* tot_mask = nullptr, size_t idx = 0) const;
@@ -107,6 +109,7 @@ private:
   // tti vars
   tti_point                   tti_rx;
   uint32_t                    current_cfix     = 0;
+  uint32_t                    current_max_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/src/stack/mac/sched_carrier.cc

@@ -88,17 +88,19 @@ void bc_sched::update_si_windows(sf_sched* tti_sched)
 
 void bc_sched::alloc_sibs(sf_sched* tti_sched)
 {
-  const uint32_t max_nof_prbs_sib = 4;
   uint32_t current_sf_idx = tti_sched->get_tti_tx_dl().sf_idx();
   uint32_t current_sfn    = tti_sched->get_tti_tx_dl().sfn();
 
   for (uint32_t sib_idx = 0; sib_idx < pending_sibs.size(); sib_idx++) {
     sched_sib_t& pending_sib = pending_sibs[sib_idx];
-    if (cc_cfg->cfg.sibs[sib_idx].len > 0 and pending_sib.is_in_window and pending_sib.n_tx < 4) {
+    // Check if SIB is configured and within window
+    if (cc_cfg->cfg.sibs[sib_idx].len == 0 or not pending_sib.is_in_window or pending_sib.n_tx >= 4) {
+      continue;
+    }
+
+    // Check if subframe index is the correct one for SIB transmission
     uint32_t nof_tx          = (sib_idx > 0) ? SRSLTE_MIN(srslte::ceil_div(cc_cfg->cfg.si_window_ms, 10), 4) : 4;
     uint32_t n_sf            = (tti_sched->get_tti_tx_dl() - pending_sibs[sib_idx].window_start);
-
-      // Check if there is any SIB to tx
     bool     sib1_flag       = (sib_idx == 0) and (current_sfn % 2) == 0 and current_sf_idx == 5;
     bool     other_sibs_flag = (sib_idx > 0) and
                            (n_sf >= (cc_cfg->cfg.si_window_ms / nof_tx) * pending_sibs[sib_idx].n_tx) and
@@ -107,27 +109,25 @@ void bc_sched::alloc_sibs(sf_sched* tti_sched)
       continue;
     }
 
-      // Attempt different number of RBGs
+    // Attempt PDSCH grants with increasing number of RBGs
-      bool success = false;
+    alloc_outcome_t ret = alloc_outcome_t::CODERATE_TOO_HIGH;
-      for (uint32_t nrbgs = 2; nrbgs < 5; ++nrbgs) {
+    for (uint32_t nrbgs = 1; nrbgs < cc_cfg->nof_rbgs and ret == alloc_outcome_t::CODERATE_TOO_HIGH; ++nrbgs) {
       rbg_interval rbg_interv = find_empty_rbg_interval(nrbgs, tti_sched->get_dl_mask());
-        if (rbg_interv.empty()) {
+      if (rbg_interv.length() != nrbgs) {
+        ret = alloc_outcome_t::RB_COLLISION;
         break;
       }
-        alloc_outcome_t ret = tti_sched->alloc_sib(bc_aggr_level, sib_idx, pending_sibs[sib_idx].n_tx, rbg_interv);
+      ret = tti_sched->alloc_sib(bc_aggr_level, sib_idx, pending_sibs[sib_idx].n_tx, rbg_interv);
-        if (ret != alloc_outcome_t::INVALID_CODERATE) {
       if (ret == alloc_outcome_t::SUCCESS) {
         // SIB scheduled successfully
-            success = true;
         pending_sibs[sib_idx].n_tx++;
       }
-          break;
-        }
-        // Attempt again, but with more RBGs
-      }
-      if (not success) {
-        logger.warning("SCHED: Could not allocate SIB=%d, len=%d", sib_idx + 1, cc_cfg->cfg.sibs[sib_idx].len);
     }
+    if (ret != alloc_outcome_t::SUCCESS) {
+      logger.warning("SCHED: Could not allocate SIB=%d, len=%d. Cause: %s",
+                     sib_idx + 1,
+                     cc_cfg->cfg.sibs[sib_idx].len,
+                     ret.to_string());
     }
   }
 }
@@ -135,21 +135,27 @@ void bc_sched::alloc_sibs(sf_sched* tti_sched)
 void bc_sched::alloc_paging(sf_sched* tti_sched)
 {
   uint32_t paging_payload = 0;
-  if (rrc->is_paging_opportunity(current_tti.to_uint(), &paging_payload) and paging_payload > 0) {
-    alloc_outcome_t ret = alloc_outcome_t::ERROR;
-    for (uint32_t nrbgs = 2; nrbgs < 5; ++nrbgs) {
-      rbg_interval rbg_interv = find_empty_rbg_interval(nrbgs, tti_sched->get_dl_mask());
 
-      ret = tti_sched->alloc_paging(bc_aggr_level, paging_payload, rbg_interv);
+  // Check if pending Paging message
-      if (ret == alloc_outcome_t::SUCCESS or ret == alloc_outcome_t::RB_COLLISION) {
+  if (not rrc->is_paging_opportunity(tti_sched->get_tti_tx_dl().to_uint(), &paging_payload) or paging_payload == 0) {
+    return;
+  }
+
+  alloc_outcome_t ret = alloc_outcome_t::CODERATE_TOO_HIGH;
+  for (uint32_t nrbgs = 1; nrbgs < cc_cfg->nof_rbgs and ret == alloc_outcome_t::CODERATE_TOO_HIGH; ++nrbgs) {
+    rbg_interval rbg_interv = find_empty_rbg_interval(nrbgs, tti_sched->get_dl_mask());
+    if (rbg_interv.length() != nrbgs) {
+      ret = alloc_outcome_t::RB_COLLISION;
       break;
     }
+
+    ret = tti_sched->alloc_paging(bc_aggr_level, paging_payload, rbg_interv);
   }
+
   if (ret != alloc_outcome_t::SUCCESS) {
     logger.warning(
         "SCHED: Could not allocate Paging with payload length=%d, cause=%s", paging_payload, ret.to_string());
   }
-  }
 }
 
 void bc_sched::reset()
@@ -167,6 +173,32 @@ ra_sched::ra_sched(const sched_cell_params_t& cfg_, sched_ue_list& ue_db_) :
   cc_cfg(&cfg_), logger(srslog::fetch_basic_logger("MAC")), ue_db(&ue_db_)
 {}
 
+alloc_outcome_t
+ra_sched::allocate_pending_rar(sf_sched* tti_sched, const pending_rar_t& rar, uint32_t& nof_grants_alloc)
+{
+  alloc_outcome_t ret = alloc_outcome_t::ERROR;
+  for (nof_grants_alloc = rar.msg3_grant.size(); nof_grants_alloc > 0; nof_grants_alloc--) {
+    ret = alloc_outcome_t::CODERATE_TOO_HIGH;
+    for (uint32_t nrbg = 1; nrbg < cc_cfg->nof_rbgs and ret == alloc_outcome_t::CODERATE_TOO_HIGH; ++nrbg) {
+      rbg_interval rbg_interv = find_empty_rbg_interval(nrbg, tti_sched->get_dl_mask());
+      if (rbg_interv.length() == nrbg) {
+        ret = tti_sched->alloc_rar(rar_aggr_level, rar, rbg_interv, nof_grants_alloc);
+      } else {
+        ret = alloc_outcome_t::RB_COLLISION;
+      }
+    }
+
+    // If allocation was not successful because there were not enough RBGs, try allocating fewer Msg3 grants
+    if (ret != alloc_outcome_t::CODERATE_TOO_HIGH and ret != alloc_outcome_t::RB_COLLISION) {
+      break;
+    }
+  }
+  if (ret != alloc_outcome_t::SUCCESS) {
+    logger.info("SCHED: RAR allocation for L=%d was postponed. Cause=%s", rar_aggr_level, ret.to_string());
+  }
+  return ret;
+}
+
 // Schedules RAR
 // On every call to this function, we schedule the oldest RAR which is still within the window. If outside the window we
 // discard it.
@@ -192,7 +224,7 @@ void ra_sched::dl_sched(sf_sched* tti_sched)
                        rar_window,
                        tti_tx_dl);
         srslte::console("%s\n", srslte::to_c_str(str_buffer));
-        logger.error("%s", srslte::to_c_str(str_buffer));
+        logger.warning("%s", srslte::to_c_str(str_buffer));
         it = pending_rars.erase(it);
         continue;
       }
@@ -200,34 +232,31 @@ void ra_sched::dl_sched(sf_sched* tti_sched)
     }
 
     // Try to schedule DCI + RBGs for RAR Grant
-    std::pair<alloc_outcome_t, uint32_t> ret = tti_sched->alloc_rar(rar_aggr_level, rar);
+    uint32_t        nof_rar_allocs = 0;
+    alloc_outcome_t ret            = allocate_pending_rar(tti_sched, rar, nof_rar_allocs);
 
+    if (ret == alloc_outcome_t::SUCCESS) {
       // If RAR allocation was successful:
-    // - in case all Msg3 grants were allocated, remove pending RAR
+      // - in case all Msg3 grants were allocated, remove pending RAR, and continue with following RAR
-    // - otherwise, erase only Msg3 grants that were allocated.
+      // - otherwise, erase only Msg3 grants that were allocated, and stop iteration
-    if (ret.first == alloc_outcome_t::SUCCESS) {
+
-      uint32_t nof_rar_allocs = ret.second;
       if (nof_rar_allocs == rar.msg3_grant.size()) {
-        pending_rars.erase(it);
+        it = pending_rars.erase(it);
       } else {
         std::copy(rar.msg3_grant.begin() + nof_rar_allocs, rar.msg3_grant.end(), rar.msg3_grant.begin());
         rar.msg3_grant.resize(rar.msg3_grant.size() - nof_rar_allocs);
-      }
         break;
       }
-
+    } else {
       // If RAR allocation was not successful:
-    // - in case of unavailable RBGs, stop loop
+      // - in case of unavailable PDCCH space, try next pending RAR allocation
-    // - otherwise, attempt to schedule next pending RAR
+      // - otherwise, stop iteration
-    logger.info("SCHED: Could not allocate RAR for L=%d, cause=%s", rar_aggr_level, ret.first.to_string());
+      if (ret != alloc_outcome_t::DCI_COLLISION) {
-    if (ret.first == alloc_outcome_t::RB_COLLISION) {
+        break;
-      // there are not enough RBs for RAR or Msg3 allocation. We can skip this TTI
-      return;
       }
-
-    // For any other type of error, continue with next pending RAR
       ++it;
     }
+  }
 }
 
 int ra_sched::dl_rach_info(dl_sched_rar_info_t rar_info)

srsenb/src/stack/mac/sched_grid.cc

@@ -22,7 +22,7 @@ const char* alloc_outcome_t::to_string() const
     case SUCCESS:
       return "success";
     case DCI_COLLISION:
-      return "dci_collision";
+      return "PDCCH position not available";
     case RB_COLLISION:
       return "rb_collision";
     case ERROR:
@@ -41,6 +41,10 @@ const char* alloc_outcome_t::to_string() const
       return "invalid rbg mask";
     case INVALID_CARRIER:
       return "invalid eNB carrier";
+    case CODERATE_TOO_HIGH:
+      return "Effective coderate is too high";
+    case NOF_ALLOCS_LIMIT:
+      return "Max number of allocations reached";
     default:
       break;
   }
@@ -118,8 +122,6 @@ void sf_grid_t::init(const sched_cell_params_t& cell_params_)
 {
   cc_cfg   = &cell_params_;
   nof_rbgs = cc_cfg->nof_rbgs;
-  si_n_rbg  = srslte::ceil_div(4, cc_cfg->P);
-  rar_n_rbg = srslte::ceil_div(3, cc_cfg->P);
 
   dl_mask.resize(nof_rbgs);
   ul_mask.resize(cc_cfg->nof_prb());
@@ -144,7 +146,6 @@ void sf_grid_t::new_tti(tti_point tti_rx_)
 
   dl_mask.reset();
   ul_mask.reset();
-  avail_rbg = nof_rbgs;
 
   // Reserve PRBs for PUCCH
   ul_mask |= pucch_mask;
@@ -181,7 +182,7 @@ alloc_outcome_t sf_grid_t::alloc_dl(uint32_t     aggr_idx,
   if (not pdcch_alloc.alloc_dci(alloc_type, aggr_idx, user, has_pusch_grant)) {
     if (user != nullptr) {
       if (logger.debug.enabled()) {
-        logger.debug("No space in PDCCH for rnti=0x%x DL tx. Current PDCCH allocation: %s",
+        logger.debug("No space in PDCCH for rnti=0x%x DL tx. Current PDCCH allocation:\n%s",
                      user->get_rnti(),
                      pdcch_alloc.result_to_string(true).c_str());
       }
@@ -191,20 +192,11 @@ alloc_outcome_t sf_grid_t::alloc_dl(uint32_t     aggr_idx,
 
   // Allocate RBGs
   dl_mask |= alloc_mask;
-  avail_rbg -= alloc_mask.count();
 
   return alloc_outcome_t::SUCCESS;
 }
 
-//! Allocates CCEs and RBs for control allocs. It allocates RBs in a contiguous manner.
+/// Allocates CCEs and RBs for control allocs. It allocates RBs in a contiguous manner.
-sf_grid_t::dl_ctrl_alloc_t sf_grid_t::alloc_dl_ctrl(uint32_t aggr_idx, alloc_type_t alloc_type)
-{
-  rbg_interval range{nof_rbgs - avail_rbg,
-                     nof_rbgs - avail_rbg + ((alloc_type == alloc_type_t::DL_RAR) ? rar_n_rbg : si_n_rbg)};
-
-  return {alloc_dl_ctrl(aggr_idx, range, alloc_type), range};
-}
-
 alloc_outcome_t sf_grid_t::alloc_dl_ctrl(uint32_t aggr_idx, rbg_interval rbg_range, alloc_type_t alloc_type)
 {
   if (alloc_type != alloc_type_t::DL_RAR and alloc_type != alloc_type_t::DL_BC and
@@ -252,7 +244,7 @@ alloc_outcome_t sf_grid_t::alloc_ul_data(sched_ue* user, prb_interval alloc, boo
     uint32_t aggr_idx = user->get_aggr_level(cc_cfg->enb_cc_idx, nof_bits);
     if (not pdcch_alloc.alloc_dci(alloc_type_t::UL_DATA, aggr_idx, user)) {
       if (logger.debug.enabled()) {
-        logger.debug("No space in PDCCH for rnti=0x%x UL tx. Current PDCCH allocation: %s",
+        logger.debug("No space in PDCCH for rnti=0x%x UL tx. Current PDCCH allocation:\n%s",
                      user->get_rnti(),
                      pdcch_alloc.result_to_string(true).c_str());
       }
@@ -271,6 +263,19 @@ bool sf_grid_t::reserve_dl_rbgs(uint32_t start_rbg, uint32_t end_rbg)
   return true;
 }
 
+void sf_grid_t::rem_last_alloc_dl(rbg_interval rbgs)
+{
+  if (pdcch_alloc.nof_allocs() == 0) {
+    logger.error("Remove DL alloc called for empty Subframe RB grid");
+    return;
+  }
+
+  pdcch_alloc.rem_last_dci();
+  rbgmask_t rbgmask(dl_mask.size());
+  rbgmask.fill(rbgs.start(), rbgs.stop());
+  dl_mask &= ~rbgmask;
+}
+
 alloc_outcome_t sf_grid_t::reserve_ul_prbs(prb_interval alloc, bool strict)
 {
   if (alloc.stop() > ul_mask.size()) {
@@ -365,69 +370,36 @@ void sf_sched::new_tti(tti_point tti_rx_, sf_sched_result* cc_results_)
 
 bool sf_sched::is_dl_alloc(uint16_t rnti) const
 {
-  for (const auto& a : data_allocs) {
+  return std::any_of(data_allocs.begin(), data_allocs.end(), [rnti](const dl_alloc_t& u) { return u.rnti == rnti; });
-    if (a.rnti == rnti) {
-      return true;
-    }
-  }
-  return false;
 }
 
 bool sf_sched::is_ul_alloc(uint16_t rnti) const
 {
-  for (const auto& a : ul_data_allocs) {
+  return std::any_of(
-    if (a.rnti == rnti) {
+      ul_data_allocs.begin(), ul_data_allocs.end(), [rnti](const ul_alloc_t& u) { return u.rnti == rnti; });
-      return true;
-    }
-  }
-  return false;
-}
-
-sf_sched::ctrl_code_t sf_sched::alloc_dl_ctrl(uint32_t aggr_lvl, uint32_t tbs_bytes, uint16_t rnti)
-{
-  ctrl_alloc_t ctrl_alloc{};
-
-  // based on rnti, check which type of alloc
-  alloc_type_t alloc_type = alloc_type_t::DL_RAR;
-  if (rnti == SRSLTE_SIRNTI) {
-    alloc_type = alloc_type_t::DL_BC;
-  } else if (rnti == SRSLTE_PRNTI) {
-    alloc_type = alloc_type_t::DL_PCCH;
-  }
-
-  /* Allocate space in the DL RBG and PDCCH grids */
-  sf_grid_t::dl_ctrl_alloc_t ret = tti_alloc.alloc_dl_ctrl(aggr_lvl, alloc_type);
-  if (not ret.outcome) {
-    return {ret.outcome, ctrl_alloc};
-  }
-
-  // Allocation Successful
-  ctrl_alloc.dci_idx   = tti_alloc.get_pdcch_grid().nof_allocs() - 1;
-  ctrl_alloc.rbg_range = ret.rbg_range;
-  ctrl_alloc.req_bytes = tbs_bytes;
-
-  return {ret.outcome, ctrl_alloc};
 }
 
 alloc_outcome_t sf_sched::alloc_sib(uint32_t aggr_lvl, uint32_t sib_idx, uint32_t sib_ntx, rbg_interval rbgs)
 {
   if (bc_allocs.size() >= sched_interface::MAX_BC_LIST) {
     logger.warning("SCHED: Maximum number of Broadcast allocations reached");
-    return alloc_outcome_t::ERROR;
+    return alloc_outcome_t::NOF_ALLOCS_LIMIT;
   }
   bc_alloc_t bc_alloc;
 
-  // Generate DCI for SIB
-  if (not generate_sib_dci(bc_alloc.bc_grant, get_tti_tx_dl(), sib_idx, sib_ntx, rbgs, *cc_cfg, tti_alloc.get_cfi())) {
-    return alloc_outcome_t::INVALID_CODERATE;
-  }
-
   // Allocate SIB RBGs and PDCCH
   alloc_outcome_t ret = tti_alloc.alloc_dl_ctrl(aggr_lvl, rbgs, alloc_type_t::DL_BC);
   if (ret != alloc_outcome_t::SUCCESS) {
     return ret;
   }
 
+  // Generate DCI for SIB
+  if (not generate_sib_dci(bc_alloc.bc_grant, get_tti_tx_dl(), sib_idx, sib_ntx, rbgs, *cc_cfg, tti_alloc.get_cfi())) {
+    // Cancel on-going allocation
+    tti_alloc.rem_last_alloc_dl(rbgs);
+    return alloc_outcome_t::CODERATE_TOO_HIGH;
+  }
+
   // Allocation Successful
   bc_alloc.dci_idx   = tti_alloc.get_pdcch_grid().nof_allocs() - 1;
   bc_alloc.rbg_range = rbgs;
@@ -441,21 +413,23 @@ alloc_outcome_t sf_sched::alloc_paging(uint32_t aggr_lvl, uint32_t paging_payloa
 {
   if (bc_allocs.size() >= sched_interface::MAX_BC_LIST) {
     logger.warning("SCHED: Maximum number of Broadcast allocations reached");
-    return alloc_outcome_t::ERROR;
+    return alloc_outcome_t::NOF_ALLOCS_LIMIT;
   }
   bc_alloc_t bc_alloc;
 
-  // Generate DCI for Paging message
-  if (not generate_paging_dci(bc_alloc.bc_grant, get_tti_tx_dl(), paging_payload, rbgs, *cc_cfg, tti_alloc.get_cfi())) {
-    return alloc_outcome_t::INVALID_CODERATE;
-  }
-
   // Allocate Paging RBGs and PDCCH
   alloc_outcome_t ret = tti_alloc.alloc_dl_ctrl(aggr_lvl, rbgs, alloc_type_t::DL_PCCH);
   if (ret != alloc_outcome_t::SUCCESS) {
     return ret;
   }
 
+  // Generate DCI for Paging message
+  if (not generate_paging_dci(bc_alloc.bc_grant, get_tti_tx_dl(), paging_payload, rbgs, *cc_cfg, tti_alloc.get_cfi())) {
+    // Cancel on-going allocation
+    tti_alloc.rem_last_alloc_dl(rbgs);
+    return alloc_outcome_t::CODERATE_TOO_HIGH;
+  }
+
   // Allocation Successful
   bc_alloc.dci_idx   = tti_alloc.get_pdcch_grid().nof_allocs() - 1;
   bc_alloc.rbg_range = rbgs;
@@ -465,53 +439,44 @@ alloc_outcome_t sf_sched::alloc_paging(uint32_t aggr_lvl, uint32_t paging_payloa
   return alloc_outcome_t::SUCCESS;
 }
 
-std::pair<alloc_outcome_t, uint32_t> sf_sched::alloc_rar(uint32_t aggr_lvl, const pending_rar_t& rar)
+alloc_outcome_t sf_sched::alloc_rar(uint32_t aggr_lvl, const pending_rar_t& rar, rbg_interval rbgs, uint32_t nof_grants)
 {
-  const uint32_t                       msg3_grant_size = 3;
+  static const uint32_t msg3_nof_prbs = 3;
-  std::pair<alloc_outcome_t, uint32_t> ret             = {alloc_outcome_t::ERROR, 0};
   if (rar_allocs.size() >= sched_interface::MAX_RAR_LIST) {
-    logger.warning("SCHED: Maximum number of RAR allocations per TTI reached.");
+    logger.info("SCHED: Maximum number of RAR allocations per TTI reached.");
-    return ret;
+    return alloc_outcome_t::NOF_ALLOCS_LIMIT;
   }
 
-  for (uint32_t nof_grants = rar.msg3_grant.size(); nof_grants > 0; nof_grants--) {
   uint32_t buf_rar           = 7 * nof_grants + 1; // 1+6 bytes per RAR subheader+body and 1 byte for Backoff
-    uint32_t total_msg3_size = msg3_grant_size * nof_grants;
+  uint32_t total_ul_nof_prbs = msg3_nof_prbs * nof_grants;
 
-    // check if there is enough space for Msg3, try again with a lower number of grants
+  // check if there is enough space for Msg3
-    if (last_msg3_prb + total_msg3_size > max_msg3_prb) {
+  if (last_msg3_prb + total_ul_nof_prbs > max_msg3_prb) {
-      ret.first = alloc_outcome_t::RB_COLLISION;
+    return alloc_outcome_t::RB_COLLISION;
-      continue;
   }
 
-    // allocate RBs and PDCCH
+  // allocate RBGs and PDCCH
-    sf_sched::ctrl_code_t ret2 = alloc_dl_ctrl(aggr_lvl, buf_rar, rar.ra_rnti);
+  alloc_outcome_t ret = tti_alloc.alloc_dl_ctrl(aggr_lvl, rbgs, alloc_type_t::DL_RAR);
-    ret.first                  = ret2.first.result;
+  if (ret != alloc_outcome_t::SUCCESS) {
-    ret.second                 = nof_grants;
-
-    if (ret.first == alloc_outcome_t::SUCCESS) {
-      sched_interface::dl_sched_rar_t rar_grant;
-      if (generate_rar_dci(rar_grant,
-                           get_tti_tx_dl(),
-                           rar,
-                           ret2.second.rbg_range,
-                           nof_grants,
-                           last_msg3_prb,
-                           *cc_cfg,
-                           tti_alloc.get_cfi())) {
-        // RAR allocation successful
-        rar_allocs.emplace_back(ret2.second, rar_grant);
-        last_msg3_prb += msg3_grant_size * nof_grants;
-        return ret;
-      }
-    } else if (ret.first != alloc_outcome_t::RB_COLLISION) {
     return ret;
   }
 
-    // if there was no space for the RAR, try again with a lower number of grants
+  // Generate DCI for RAR
+  rar_alloc_t rar_alloc;
+  if (not generate_rar_dci(
+          rar_alloc.rar_grant, get_tti_tx_dl(), rar, rbgs, nof_grants, last_msg3_prb, *cc_cfg, tti_alloc.get_cfi())) {
+    // Cancel on-going allocation
+    tti_alloc.rem_last_alloc_dl(rbgs);
+    return alloc_outcome_t::CODERATE_TOO_HIGH;
   }
 
-  logger.info("SCHED: RAR allocation postponed due to lack of RBs");
+  // RAR allocation successful
+  rar_alloc.alloc_data.dci_idx   = tti_alloc.get_pdcch_grid().nof_allocs() - 1;
+  rar_alloc.alloc_data.rbg_range = rbgs;
+  rar_alloc.alloc_data.req_bytes = buf_rar;
+  rar_allocs.push_back(rar_alloc);
+  last_msg3_prb += total_ul_nof_prbs * nof_grants;
+
   return ret;
 }
 
@@ -531,7 +496,7 @@ alloc_outcome_t sf_sched::alloc_dl_user(sched_ue* user, const rbgmask_t& user_ma
 {
   if (data_allocs.size() >= sched_interface::MAX_DATA_LIST) {
     logger.warning("SCHED: Maximum number of DL allocations reached");
-    return alloc_outcome_t::ERROR;
+    return alloc_outcome_t::NOF_ALLOCS_LIMIT;
   }
 
   if (is_dl_alloc(user->get_rnti())) {

srsenb/src/stack/mac/sched_phy_ch/sched_dci.cc

@@ -319,8 +319,9 @@ void log_broadcast_allocation(const sched_interface::dl_sched_bc_t& bc,
   fmt::format_to(str_buffer, "{}", rbg_range);
 
   if (bc.type == sched_interface::dl_sched_bc_t::bc_type::BCCH) {
-    logger.debug("SCHED: SIB%d, rbgs=(%d,%d), dci=(%d,%d), rv=%d, len=%d, period=%d, mcs=%d",
+    logger.debug("SCHED: SIB%d, cc=%d, rbgs=(%d,%d), dci=(%d,%d), rv=%d, len=%d, period=%d, mcs=%d",
                  bc.index + 1,
+                 cell_params.enb_cc_idx,
                  rbg_range.start(),
                  rbg_range.stop(),
                  bc.dci.location.L,
@@ -330,8 +331,9 @@ void log_broadcast_allocation(const sched_interface::dl_sched_bc_t& bc,
                  cell_params.cfg.sibs[bc.index].period_rf,
                  bc.dci.tb[0].mcs_idx);
   } else {
-    logger.info("SCHED: PCH, rbgs=%s, dci=(%d,%d), tbs=%d, mcs=%d",
+    logger.info("SCHED: PCH, cc=%d, rbgs=%s, dci=(%d,%d), tbs=%d, mcs=%d",
                 srslte::to_c_str(str_buffer),
+                cell_params.enb_cc_idx,
                 bc.dci.location.L,
                 bc.dci.location.ncce,
                 bc.tbs,

srsenb/src/stack/mac/sched_phy_ch/sf_cch_allocator.cc

@@ -38,6 +38,7 @@ void sf_cch_allocator::new_tti(tti_point tti_rx_)
   }
   dci_record_list.clear();
   current_cfix     = cc_cfg->sched_cfg->min_nof_ctrl_symbols - 1;
+  current_max_cfix = cc_cfg->sched_cfg->max_nof_ctrl_symbols - 1;
 }
 
 const cce_cfi_position_table*
@@ -70,7 +71,7 @@ bool sf_cch_allocator::alloc_dci(alloc_type_t alloc_type, uint32_t aggr_idx, sch
   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));
+  } while (not success and current_cfix < current_max_cfix and set_cfi(get_cfi() + 1));
 
   if (not success) {
     // DCI allocation failed. go back to original CFI
@@ -82,9 +83,45 @@ bool sf_cch_allocator::alloc_dci(alloc_type_t alloc_type, uint32_t aggr_idx, sch
 
   // DCI record allocation successful
   dci_record_list.push_back(record);
+
+  if (is_dl_ctrl_alloc(alloc_type)) {
+    // Dynamic CFI not yet supported for DL control allocations, as coderate can be exceeded
+    current_max_cfix = current_cfix;
+  }
+
   return true;
 }
 
+void sf_cch_allocator::rem_last_dci()
+{
+  assert(not dci_record_list.empty());
+
+  // Remove DCI record
+  dci_record_list.pop_back();
+
+  // Remove leaves of PDCCH position decisions
+  auto& tree    = alloc_trees[current_cfix];
+  tree.prev_end = tree.prev_start;
+  if (dci_record_list.empty()) {
+    tree.prev_start = 0;
+  } else {
+    tree.prev_start = tree.dci_alloc_tree[tree.prev_start].parent_idx;
+    // Discover other tree nodes with same level
+    while (tree.prev_start > 0) {
+      uint32_t count = 0;
+      while (tree.dci_alloc_tree[tree.prev_start - 1].parent_idx >= 0) {
+        count++;
+      }
+      if (count == dci_record_list.size()) {
+        tree.prev_start--;
+      } else {
+        break;
+      }
+    }
+  }
+  tree.dci_alloc_tree.erase(tree.dci_alloc_tree.begin() + tree.prev_end, tree.dci_alloc_tree.end());
+}
+
 bool sf_cch_allocator::alloc_dci_record(const alloc_record_t& record, uint32_t cfix)
 {
   bool  ret  = false;

srsenb/src/stack/mac/schedulers/sched_time_pf.cc

@@ -145,7 +145,7 @@ uint32_t sched_time_pf::try_ul_alloc(ue_ctxt& ue_ctxt, sched_ue& ue, sf_sched* t
                           : 0;
   }
   if (code == alloc_outcome_t::DCI_COLLISION) {
-    logger.info("SCHED: Couldn't find space in PDCCH for UL retx of rnti=0x%x", ue.get_rnti());
+    logger.info("SCHED: rnti=0x%x, cc=%d, Couldn't find space in PDCCH for UL tx", ue.get_rnti(), cc_cfg->enb_cc_idx);
   }
   return estim_tbs_bytes;
 }

srsenb/src/stack/mac/schedulers/sched_time_rr.cc

@@ -142,7 +142,8 @@ void sched_time_rr::sched_ul_newtxs(sched_ue_list& ue_db, sf_sched* tti_sched, s
     }
     alloc_outcome_t ret = tti_sched->alloc_ul_user(&user, alloc);
     if (ret == alloc_outcome_t::DCI_COLLISION) {
-      logger.info("SCHED: Couldn't find space in PDCCH for UL tx of rnti=0x%x", user.get_rnti());
+      logger.info(
+          "SCHED: rnti=0x%x, cc=%d, Couldn't find space in PDCCH for UL tx", user.get_rnti(), cc_cfg->enb_cc_idx);
     }
   }
 }

srsenb/test/mac/sched_ca_test.cc

@@ -17,7 +17,7 @@
 
 using namespace srsenb;
 
-uint32_t const seed = std::chrono::system_clock::now().time_since_epoch().count();
+uint32_t seed = std::chrono::system_clock::now().time_since_epoch().count();
 
 /*******************
  *     Logging     *
@@ -157,7 +157,7 @@ int test_scell_activation(uint32_t sim_number, test_scell_activation_params para
     }
   };
   generate_data(20, 1.0, P_ul_sr, randf());
-  tester.test_next_ttis(generator.tti_events);
+  TESTASSERT(tester.test_next_ttis(generator.tti_events) == SRSLTE_SUCCESS);
 
   // Event: Reconf Complete. Activate SCells. Check if CE correctly transmitted
   generator.step_tti();
@@ -169,7 +169,7 @@ int test_scell_activation(uint32_t sim_number, test_scell_activation_params para
     user->ue_sim_cfg->ue_cfg.supported_cc_list[i].active     = true;
     user->ue_sim_cfg->ue_cfg.supported_cc_list[i].enb_cc_idx = cc_idxs[i];
   }
-  tester.test_next_ttis(generator.tti_events);
+  TESTASSERT(tester.test_next_ttis(generator.tti_events) == SRSLTE_SUCCESS);
   auto activ_list = tester.get_enb_ue_cc_map(rnti1);
   for (uint32_t i = 0; i < cc_idxs.size(); ++i) {
     TESTASSERT(activ_list[i] >= 0);
@@ -187,7 +187,7 @@ int test_scell_activation(uint32_t sim_number, test_scell_activation_params para
       }
     }
     generator.step_tti();
-    tester.test_next_ttis(generator.tti_events);
+    TESTASSERT(tester.test_next_ttis(generator.tti_events) == SRSLTE_SUCCESS);
   }
 
   // Event: Wait for UE to receive and ack CE. Send cqi==0, which should not activate the SCell
@@ -198,12 +198,12 @@ int test_scell_activation(uint32_t sim_number, test_scell_activation_params para
       generator.step_tti();
     }
   }
-  tester.test_next_ttis(generator.tti_events);
+  TESTASSERT(tester.test_next_ttis(generator.tti_events) == SRSLTE_SUCCESS);
   // The UE should now have received the CE
 
   // Event: Generate a bit more data, it should *not* go through SCells until we send a CQI
   generate_data(5, P_dl, P_ul_sr, randf());
-  tester.test_next_ttis(generator.tti_events);
+  TESTASSERT(tester.test_next_ttis(generator.tti_events) == SRSLTE_SUCCESS);
   TESTASSERT(tester.sched_stats->users[rnti1].tot_dl_sched_data[params.pcell_idx] > 0);
   TESTASSERT(tester.sched_stats->users[rnti1].tot_ul_sched_data[params.pcell_idx] > 0);
   for (uint32_t i = 1; i < cc_idxs.size(); ++i) {
@@ -217,7 +217,7 @@ int test_scell_activation(uint32_t sim_number, test_scell_activation_params para
     tester.dl_cqi_info(tester.tti_rx.to_uint(), rnti1, cc_idxs[i], cqi);
   }
   generate_data(10, 1.0, 1.0, 1.0);
-  tester.test_next_ttis(generator.tti_events);
+  TESTASSERT(tester.test_next_ttis(generator.tti_events) == SRSLTE_SUCCESS);
   uint64_t tot_dl_sched_data = 0;
   uint64_t tot_ul_sched_data = 0;
   for (const auto& c : cc_idxs) {

srsenb/test/mac/sched_common_test_suite.cc

@@ -316,7 +316,8 @@ int test_dci_content_common(const sf_output_res_t& sf_out, uint32_t enb_cc_idx)
     uint32_t       nof_re   = srslte_ra_dl_grant_nof_re(&cell_params.cfg.cell, &dl_sf, &grant);
     float          coderate = srslte_coderate(tbs * 8, nof_re);
     const uint32_t Qm       = 2;
-    CONDERROR(coderate > 0.930f * Qm, "Max coderate was exceeded from broadcast DCI");
+    CONDERROR(
+        coderate > 0.930f * Qm, "Max coderate was exceeded from %s DCI", dci.rnti == SRSLTE_SIRNTI ? "SIB" : "RAR");
     return SRSLTE_SUCCESS;
   };
 

srsenb/test/mac/sched_ue_ded_test_suite.cc

@@ -78,7 +78,7 @@ int test_pdsch_grant(const sim_enb_ctxt_t&                   enb_ctxt,
   uint32_t nof_retx = get_nof_retx(pdsch.dci.tb[0].rv); // 0..3
   if (h.nof_txs == 0 or h.ndi != pdsch.dci.tb[0].ndi) {
     // It is newtx
-    CONDERROR(nof_retx != 0, "Invalid rv index for new tx");
+    CONDERROR(nof_retx != 0, "Invalid rv index for new DL tx");
     CONDERROR(h.active, "DL newtx for already active DL harq pid=%d", h.pid);
   } else {
     // it is retx
@@ -196,7 +196,7 @@ int test_ul_sched_result(const sim_enb_ctxt_t& enb_ctxt, const sf_output_res_t&
 
         if (h.nof_txs == 0 or h.ndi != pusch_ptr->dci.tb.ndi) {
           // newtx
-          CONDERROR(nof_retx != 0, "Invalid rv index for new tx");
+          CONDERROR(nof_retx != 0, "Invalid rv index for new UL tx");
           CONDERROR(pusch_ptr->current_tx_nb != 0, "UL HARQ retxs need to have been previously transmitted");
           CONDERROR(not h_inactive, "New tx for already active UL HARQ");
           CONDERROR(not pusch_ptr->needs_pdcch and ue.msg3_tti_rx.is_valid() and sf_out.tti_rx > ue.msg3_tti_rx,