sched: draft design of scheduler slicing

Author: frankist

include/srsran/ran/rrm.h

@@ -14,10 +14,16 @@
 
 namespace srsran {
 
-/// O-RAN.WG3.E2SM-RC-R003-v3.00 Section 8.4.3.6
+/// Identifier of a RRM Policy Member.
+/// \remark See O-RAN.WG3.E2SM-RC-R003-v3.00 Section 8.4.3.6
 struct rrm_policy_member {
   std::string plmn_id;
   s_nssai_t   s_nssai;
+
+  bool operator==(const rrm_policy_member& other) const
+  {
+    return plmn_id == other.plmn_id and s_nssai == other.s_nssai;
+  }
 };
 
 struct rrm_policy_ratio_group {

include/srsran/ran/s_nssai.h

@@ -20,6 +20,8 @@ struct s_nssai_t {
   uint8_t sst = 0;
   /// Slice Differentiator (max 24bits).
   std::optional<uint32_t> sd;
+
+  bool operator==(const s_nssai_t& other) const { return sst == other.sst && sd == other.sd; }
 };
 
 } // namespace srsran

include/srsran/scheduler/config/cell_rrm_policy_config.h

@@ -0,0 +1,28 @@
+/*
+ *
+ * Copyright 2021-2024 Software Radio Systems Limited
+ *
+ * By using this file, you agree to the terms and conditions set
+ * forth in the LICENSE file which can be found at the top level of
+ * the distribution.
+ *
+ */
+
+#pragma once
+
+#include "srsran/ran/rrm.h"
+#include "srsran/ran/s_nssai.h"
+
+namespace srsran {
+
+/// Cell-specific Default RAN slice configuration.
+struct cell_rrm_policy_config {
+  /// RRM Policy identifier.
+  rrm_policy_member rrc_member;
+  /// Sets the minimum percentage of PRBs to be allocated to this group.
+  unsigned min_prb_ratio = 0;
+  /// Sets the maximum percentage of PRBs to be allocated to this group.
+  unsigned max_prb_ratio = MAX_NOF_PRBS;
+};
+
+} // namespace srsran

include/srsran/scheduler/config/logical_channel_config.h

@@ -12,6 +12,7 @@
 
 #include "srsran/adt/optional.h"
 #include "srsran/ran/lcid.h"
+#include "srsran/ran/rrm.h"
 #include "srsran/ran/sr_configuration.h"
 #include "srsran/scheduler/config/logical_channel_group.h"
 
@@ -26,6 +27,7 @@ struct logical_channel_config {
   std::optional<scheduling_request_id> sr_id;
   bool                                 lc_sr_mask;
   bool                                 lc_sr_delay_timer_applied;
+  rrm_policy_member                    rrm_policy;
 };
 
 } // namespace srsran

include/srsran/scheduler/scheduler_configurator.h

@@ -31,6 +31,7 @@
 #include "srsran/ran/subcarrier_spacing.h"
 #include "srsran/ran/tdd/tdd_ul_dl_config.h"
 #include "srsran/scheduler/config/bwp_configuration.h"
+#include "srsran/scheduler/config/cell_rrm_policy_config.h"
 #include "srsran/scheduler/config/dmrs.h"
 #include "srsran/scheduler/config/logical_channel_config.h"
 #include "srsran/scheduler/config/serving_cell_config.h"
@@ -91,6 +92,9 @@ struct sched_cell_configuration_request_message {
   /// List of nzp-CSI-RS resources common to all UEs.
   std::vector<nzp_csi_rs_resource> nzp_csi_rs_res_list;
 
+  /// List of RAN slices to support in the scheduler.
+  std::vector<cell_rrm_policy_config> rrm_policy_members;
+
   unsigned ntn_cs_koffset = 0;
 };
 

lib/scheduler/CMakeLists.txt

@@ -37,6 +37,8 @@ set(SOURCES
         support/dci_builder.cpp
         support/sch_pdu_builder.cpp
         support/csi_report_helpers.cpp
+        slicing/slice_scheduler.cpp
+        slicing/ran_slice_instance.cpp
         cell_scheduler.cpp
         scheduler_factory.cpp
         scheduler_impl.cpp

lib/scheduler/config/cell_configuration.cpp

@@ -36,6 +36,7 @@ cell_configuration::cell_configuration(const scheduler_expert_config&
   pucch_guardbands(msg.pucch_guardbands),
   zp_csi_rs_list(msg.zp_csi_rs_list),
   nzp_csi_rs_list(msg.nzp_csi_rs_res_list),
+  rrm_policy_members(msg.rrm_policy_members),
   // SSB derived params.
   ssb_case(band_helper::get_ssb_pattern(msg.dl_carrier.band, msg.ssb_config.scs)),
   paired_spectrum(band_helper::is_paired_spectrum(msg.dl_carrier.band)),

lib/scheduler/config/cell_configuration.h

@@ -55,6 +55,9 @@ class cell_configuration
   /// List of nzp-CSI-RS resources.
   std::vector<nzp_csi_rs_resource> nzp_csi_rs_list;
 
+  /// List of RRM Policy members configured for this cell.
+  std::vector<cell_rrm_policy_config> rrm_policy_members;
+
   // Derived Parameters.
   ssb_pattern_case ssb_case;
   bool             paired_spectrum;

lib/scheduler/slicing/ran_slice_candidate.h

@@ -0,0 +1,82 @@
+/*
+ *
+ * Copyright 2021-2024 Software Radio Systems Limited
+ *
+ * By using this file, you agree to the terms and conditions set
+ * forth in the LICENSE file which can be found at the top level of
+ * the distribution.
+ *
+ */
+
+#pragma once
+
+#include "ran_slice_instance.h"
+
+namespace srsran {
+namespace detail {
+
+template <bool IsDl>
+class common_ran_slice_candidate
+{
+  struct candidate_deleter {
+    void operator()(ran_slice_instance* p)
+    {
+      if (p != nullptr) {
+        if constexpr (IsDl) {
+          p->pdsch_completed();
+        } else {
+          p->pusch_completed();
+        }
+      }
+    }
+  };
+
+public:
+  common_ran_slice_candidate(ran_slice_instance* instance_) : inst(instance_, candidate_deleter{}) {}
+
+  ran_slice_id_t                              id() const { return inst->id; }
+  [[nodiscard]] const cell_rrm_policy_config& cfg() const { return inst->cfg; }
+  scheduler_policy&                           policy() { return *inst->policy; }
+
+  bool is_candidate(du_ue_index_t ue_idx) const { return inst->is_candidate(ue_idx); }
+  bool is_candidate(du_ue_index_t ue_idx, lcid_t lcid) const { return inst->is_candidate(ue_idx, lcid); }
+
+  /// Signal that the allocations for this slice are complete.
+  void clear() { inst.reset(); }
+
+  /// Register that a new grant was allocated for a given UE.
+  void store_grant(unsigned nof_rbs)
+  {
+    if constexpr (IsDl) {
+      inst->store_pdsch_grant(nof_rbs);
+    } else {
+      inst->store_pusch_grant(nof_rbs);
+    }
+  }
+
+  /// Remaining bytes to allocate for the given slice.
+  [[nodiscard]] unsigned remaining_rbs() const
+  {
+    if constexpr (IsDl) {
+      return inst->cfg.max_prb_ratio < inst->pdsch_rb_count ? 0 : inst->cfg.max_prb_ratio - inst->pdsch_rb_count;
+    }
+    return inst->cfg.max_prb_ratio < inst->pusch_rb_count ? 0 : inst->cfg.max_prb_ratio - inst->pusch_rb_count;
+  }
+
+protected:
+  std::unique_ptr<ran_slice_instance, candidate_deleter> inst;
+};
+
+} // namespace detail
+
+/// \brief Handle to fetch and update the state of a RAN slice in a given DL slot.
+///
+/// On destruction, the slice is marked as completed for the current slot and won't be considered as a candidate again.
+using dl_ran_slice_candidate = detail::common_ran_slice_candidate<true>;
+
+/// Interface to fetch and update the state of a RAN slice in a given UL slot.
+///
+/// On destruction, the slice is marked as completed for the current slot and won't be considered as a candidate again.
+using ul_ran_slice_candidate = detail::common_ran_slice_candidate<false>;
+
+} // namespace srsran

lib/scheduler/slicing/ran_slice_id.h

@@ -0,0 +1,22 @@
+/*
+ *
+ * Copyright 2021-2024 Software Radio Systems Limited
+ *
+ * By using this file, you agree to the terms and conditions set
+ * forth in the LICENSE file which can be found at the top level of
+ * the distribution.
+ *
+ */
+
+#pragma once
+
+#include "srsran/adt/strong_type.h"
+#include <cstdint>
+
+namespace srsran {
+
+/// RAN slice identifier that should be unique for a given cell,PLMN,S-NSSAI.
+struct ran_slice_id_tag {};
+using ran_slice_id_t = strong_type<uint8_t, struct ran_slice_id_tag, strong_increment_decrement>;
+
+} // namespace srsran