sched: only reserve CSI/SR resources after running the multiplexing algorithm

Author: jonathan-srs

lib/scheduler/pucch_scheduling/pucch_allocator_impl.cpp

@@ -19,6 +19,7 @@
 #include "srsran/ran/resource_allocation/ofdm_symbol_range.h"
 #include "srsran/scheduler/result/sched_result.h"
 #include "srsran/srslog/srslog.h"
+#include "srsran/support/srsran_assert.h"
 #include <algorithm>
 #include <array>
 #include <variant>
@@ -1285,6 +1286,28 @@ pucch_allocator_impl::multiplex_and_allocate_pucch(cell_slot_resource_allocator&
     return std::nullopt;
   }
 
+  // Reserve the resources needed for the multiplexed grants.
+  if (grants_to_tx.sr_resource.has_value()) {
+    const auto* sr_res = guard.reserve_sr_resource();
+    if (sr_res == nullptr) {
+      logger.error("rnti={}: the multiplexing of PUCCH resources for slot={} could not be completed. Cause: SR "
+                   "resource not available",
+                   current_grants.rnti,
+                   pucch_slot_alloc.slot);
+      return std::nullopt;
+    }
+  }
+  if (grants_to_tx.csi_resource.has_value()) {
+    const auto* csi_res = guard.reserve_csi_resource();
+    if (csi_res == nullptr) {
+      logger.error("rnti={}: the multiplexing of PUCCH resources for slot={} could not be completed. Cause: CSI "
+                   "resource not available",
+                   current_grants.rnti,
+                   pucch_slot_alloc.slot);
+      return std::nullopt;
+    }
+  }
+
   // If the grants for the common PUCCH resource are provided, this PUCCH is allocated by the fallback scheduler.
   if (common_grants.has_value()) {
     // At most 3 PUCCH resources with 2 grants each.
@@ -1374,12 +1397,9 @@ pucch_allocator_impl::get_pucch_res_pre_multiplexing(pucch_resource_manager::ue_
     // Get the resource from the resource manager; the UCI bits will be added later.
     // NOTE: if the SR resource was already assigned to this UE, the resource manager will only return the PUCCH
     // config that was reserved previously.
-    const pucch_resource* sr_resource = guard.reserve_sr_resource();
-    if (sr_resource == nullptr) {
-      srsran_assertion_failure("rnti={}: PUCCH SR resource previously reserved not available anymore",
-                               ue_current_grants.rnti);
-      return std::nullopt;
-    }
+    const pucch_resource* sr_resource = guard.peek_sr_resource();
+    srsran_assert(
+        sr_resource != nullptr, "rnti={}: Peeking a PUCCH SR resource returned nullptr", ue_current_grants.rnti);
     sr_candidate_grant.set_res_config(*sr_resource);
     // Only copy the SR bits, as at this stage we only need to consider the UCI bits assuming the resources still
     // need to be multiplexed.
@@ -1395,12 +1415,9 @@ pucch_allocator_impl::get_pucch_res_pre_multiplexing(pucch_resource_manager::ue_
     // Get the resource from the resource manager; the UCI bits will be added later.
     // NOTE: if the CSI resource was already assigned to this UE, the resource manager will only return the PUCCH
     // config that was reserved previously.
-    const pucch_resource* csi_resource = guard.reserve_csi_resource();
-    if (csi_resource == nullptr) {
-      srsran_assertion_failure("rnti={}: PUCCH CSI resource previously reserved not available anymore",
-                               ue_current_grants.rnti);
-      return std::nullopt;
-    }
+    const pucch_resource* csi_resource = guard.peek_csi_resource();
+    srsran_assert(
+        csi_resource != nullptr, "rnti={}: Peeking a PUCCH CSI resource returned nullptr", ue_current_grants.rnti);
     csi_candidate_grant.set_res_config(*csi_resource);
     // Only copy the HARQ-ACK bits, as at this stage we only need to consider the UCI bits assuming the resources
     // still need to be multiplexed.

lib/scheduler/pucch_scheduling/pucch_resource_manager.cpp

@@ -231,6 +231,52 @@ const pucch_resource* pucch_resource_manager::ue_reservation_guard::reserve_csi_
   return res_cfg;
 }
 
+const pucch_resource* pucch_resource_manager::ue_reservation_guard::peek_sr_resource() const
+{
+  srsran_assert(parent != nullptr, "Trying to make a new PUCCH resource reservation after commit has been called");
+  const auto& pucch_cfg = ue_cfg.init_bwp().ul_ded->pucch_cfg.value();
+
+  // We assume each UE only has 1 SR Resource Config configured.
+  srsran_sanity_check(pucch_cfg.sr_res_list.size() == 1, "UE SR resource list must have size 1.");
+  const unsigned cell_res_id = pucch_cfg.sr_res_list[0].pucch_res_id.cell_res_id;
+
+  // Search for the PUCCH resource with the correct PUCCH resource ID from the PUCCH resource list.
+  const auto& pucch_res_list = pucch_cfg.pucch_res_list;
+  const auto* res_cfg =
+      std::find_if(pucch_res_list.begin(), pucch_res_list.end(), [cell_res_id](const pucch_resource& res) {
+        return res.res_id.cell_res_id == cell_res_id;
+      });
+  srsran_assert(res_cfg != pucch_res_list.end(),
+                "rnti={}: PUCCH resource with cell_res_id={} not found in PUCCH resource list",
+                rnti,
+                cell_res_id);
+
+  return res_cfg;
+}
+
+const pucch_resource* pucch_resource_manager::ue_reservation_guard::peek_csi_resource() const
+{
+  srsran_assert(parent != nullptr, "Trying to make a new PUCCH resource reservation after commit has been called");
+
+  // Get CSI specific PUCCH resource ID from the CSI meas config.
+  const int cell_res_id_int = get_csi_cell_res_id(ue_cfg);
+  srsran_assert(cell_res_id_int >= 0, "rnti={}: CSI PUCCH resource index could not be found", rnti);
+  const auto cell_res_id = static_cast<unsigned>(cell_res_id_int);
+
+  // Search for the PUCCH resource with the correct PUCCH resource ID from the PUCCH resource list.
+  const auto& pucch_res_list = ue_cfg.init_bwp().ul_ded->pucch_cfg.value().pucch_res_list;
+  const auto* res_cfg =
+      std::find_if(pucch_res_list.begin(), pucch_res_list.end(), [cell_res_id](const pucch_resource& res) {
+        return res.res_id.cell_res_id == cell_res_id;
+      });
+  srsran_assert(res_cfg != pucch_res_list.end(),
+                "rnti={}: PUCCH resource with cell_res_id={} not found in PUCCH resource list",
+                rnti,
+                cell_res_id);
+
+  return res_cfg;
+}
+
 bool pucch_resource_manager::ue_reservation_guard::release_harq_set_0_resource()
 {
   return release_harq_resource(pucch_res_set_idx::set_0);

lib/scheduler/pucch_scheduling/pucch_resource_manager.h

@@ -109,6 +109,12 @@ class pucch_resource_manager
     /// \return A pointer to the resource configuration, if available. Otherwise, \c nullptr.
     const pucch_resource* reserve_csi_resource();
 
+    /// Peek at the configured SR PUCCH resource for the UE without reserving it.
+    const pucch_resource* peek_sr_resource() const;
+
+    /// Peek at the configured CSI PUCCH resource for the UE without reserving it.
+    const pucch_resource* peek_csi_resource() const;
+
     /// \brief Release PUCCH resource from Resource Set ID 0 from being allocated to a given UE.
     /// \param[in] slot_harq slot for which the PUCCH resource was scheduled.
     /// \return True if the resource for the UE was found in the allocation records for the given slot.