Rework CARR.PDSCHMCSDist metric

CARR.PDSCHMCSDist (3GPP TS 28.552 §5.1.1.12.1) and its du_stats histogram
already existed, but the metric was never collected and the reader indexed
the histogram incorrectly. Rework it into a correct PRB-weighted 3D
histogram over (rank, MCS-table, MCS-index).

- gNB_scheduler_dlsch.c: add the missing collection hook in the DL
  scheduling path; increment the (rank, MCS-table, MCS) bin by the number of
  scheduled PRBs on each PDSCH. mcsTableIdx is 0-based (0..2), so it is used
  directly to index the MCS-table axis of the histogram.
- ran_func_kpm_subs.c: make fill_CARR_PDSCHMCSDist() fully label-driven;
  reject with NO_VALUE if any of distBinX/Y/Z is absent. distBinX (rank) and
  distBinY (MCS table) are 1-based on the wire and converted to 0-based
  indices; distBinZ (MCS index) is already 0-based and used directly, reading
  du_stats->pdsch_mcs_dist[rank-1][table-1][mcs].

Carried as E2SM-KPM Style 1 measurement (Indication Message Format 1) with
standard MeasurementLabel fields distBinX/Y/Z (INTEGER 1..65535).
Advertised by DU and monolithic gNB node types.
Signed-off-by: Noemi Giustini <giustini.n@northeastern.edu>

openair2/E2AP/RAN_FUNCTION/O-RAN/ran_func_kpm_subs.c

@@ -219,19 +219,29 @@ static meas_record_lst_t fill_CARR_PDSCHMCSDist(const label_info_lst_t label,
                                                 __attribute__((unused)) const size_t ue_idx,
                                                 __attribute__((unused))e2_node_level_stats_t* node_stats)
 {
-  meas_record_lst_t meas_record = {.value = INTEGER_MEAS_VALUE};
+  meas_record_lst_t meas_record = {0};
 
-  uint32_t bin_x = *label.distBinX, bin_y = *label.distBinY, bin_z = *label.distBinZ;
+  if (label.distBinX == NULL || label.distBinY == NULL || label.distBinZ == NULL) {
+    printf("[E2 AGENT][E2SM-KPM] CARR.PDSCHMCSDist requested without distBinX/Y/Z labels; "
+           "TS 28.552 5.1.1.12.1 defines no aggregate value, reporting NO_VALUE\n");
+    meas_record.value = NO_VALUE_MEAS_VALUE;
+    return meas_record;
+  }
 
-  NR_du_stats_t* du_stats = &RC.nrmac[0]->du_stats;
+  const uint32_t bin_x = *label.distBinX;
+  const uint32_t bin_y = *label.distBinY;
+  const uint32_t bin_z = *label.distBinZ;
 
-  if (bin_x <= 8 && bin_y <= 3 && bin_z <= 31) {
-    meas_record.int_val = du_stats->pdsch_mcs_dist[bin_x - 1][bin_y - 1][bin_z];
-  } else {
-    printf("[E2 AGENT] Unknown binX %d, binY %d, binZ %d for \"CARR.PDSCHMCSDist\" measurement\n", bin_x, bin_y, bin_z);
-    meas_record.int_val = 0;
+  if (bin_x < 1 || bin_x > NR_KPM_MAX_LAYERS || bin_y < 1 || bin_y > NR_KPM_NB_MCS_TABLE_DL || bin_z > NR_KPM_NB_MCS - 1) {
+    printf("[E2 AGENT][E2SM-KPM] CARR.PDSCHMCSDist: bin out of range (X=%u Y=%u Z=%u), reporting NO_VALUE\n",
+           bin_x, bin_y, bin_z);
+    meas_record.value = NO_VALUE_MEAS_VALUE;
+    return meas_record;
   }
 
+  const NR_du_stats_t* du_stats = &RC.nrmac[0]->du_stats;
+  meas_record.value = INTEGER_MEAS_VALUE;
+  meas_record.int_val = du_stats->pdsch_mcs_dist[bin_x - 1][bin_y - 1][bin_z];
   return meas_record;
 }
 #endif

openair2/E2AP/README.md

@@ -101,6 +101,7 @@ From 3GPP TS 28.552, we support the following list:
   * `DRB.UEThpUl`
   * `RRU.PrbTotDl`
   * `RRU.PrbTotUl`
+  * `CARR.PDSCHMCSDist`
 
 From `O-RAN.WG3.E2SM-KPM-version` specification, we implemented:
   * REPORT Service Style 4 ("Common condition-based, UE-level" - section 7.4.5) - fetch above measurements per each UE based on the common S-NSSAI `(1, 0xffffff)` condition

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c

@@ -1261,6 +1261,11 @@ void post_process_dlsch(gNB_MAC_INST *nr_mac,
         tpc);
   DevAssert(sched_pdsch->rbSize > 0);
 
+  DevAssert(nrOfLayers >= 1 && nrOfLayers <= NR_KPM_MAX_LAYERS);
+  DevAssert(current_BWP->mcsTableIdx >= 0 && current_BWP->mcsTableIdx < NR_KPM_NB_MCS_TABLE_DL);
+  DevAssert(sched_pdsch->mcs < NR_KPM_NB_MCS);
+  nr_mac->du_stats.pdsch_mcs_dist[nrOfLayers - 1][current_BWP->mcsTableIdx][sched_pdsch->mcs] += sched_pdsch->rbSize;
+
   const int bwp_id = current_BWP->bwp_id;
   const int coresetid = sched_ctrl->coreset->controlResourceSetId;
 

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -1139,6 +1139,11 @@ typedef struct {
   NR_ControlResourceSet_t coreset;
 } NR_sched_ctrl_sib1_t;
 
+/* Dimensions of the per-cell MCS distribution histograms (3GPP TS 28.552 §5.1.1.12). */
+#define NR_KPM_MAX_LAYERS       8  /* RI: 1..8                  */
+#define NR_KPM_NB_MCS_TABLE_DL  3  /* PDSCH MCS tables: 1..3    */
+#define NR_KPM_NB_MCS           32 /* MCS index: 0..31          */
+
 typedef struct NR_du_stats {
   /// cell-wide wide-band CQI distribution, see 28.552 5.1.1.11.1;
   /// 0-15 CQI, 1-8 RI, 1-3 CQI table
@@ -1146,7 +1151,7 @@ typedef struct NR_du_stats {
 
   /// cell-wide MCS distribution in PDSCH, see 28.552 5.1.1.12.1
   /// 1-8 RI, 1-3 MCS table, 0-31 MCS value
-  uint32_t pdsch_mcs_dist[8][3][32];
+  uint32_t pdsch_mcs_dist[NR_KPM_MAX_LAYERS][NR_KPM_NB_MCS_TABLE_DL][NR_KPM_NB_MCS];
 
   /// cell-wide MCS distribution in PUSCH, see 28.552 5.1.1.12.1
   /// 1-8 RI, 1-2 MCS table, 0-31 MCS value