Check UL resource first for retransmission

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_ulsch.c

@@ -569,22 +569,12 @@ void pf_ul(module_id_t module_id,
     sched_ctrl->sched_pusch.ul_harq_pid = sched_ctrl->retrans_ul_harq.head;
     if (sched_ctrl->sched_pusch.ul_harq_pid >= 0) {
       /* RETRANSMISSION: Allocate retransmission*/
-      /* Find free CCE */
-      bool freeCCE = find_free_CCE(module_id, slot, UE_id);
-      if (!freeCCE) {
-        LOG_D(MAC, "%4d.%2d no free CCE for retransmission UL DCI UE %04x\n", frame, slot, UE_info->rnti[UE_id]);
-        continue;
-      }
-      /* reduce max_num_ue once we are sure UE can be allocated, i.e., has CCE */
-      max_num_ue--;
-      if (max_num_ue < 0)
-        return;
 
-      /* Save shced_frame and sched_slot before overwrite by previous PUSCH filed */
+      /* Save shced_frame and sched_slot before overwrite by previous PUSCH field */
       NR_UE_ul_harq_t *cur_harq = &sched_ctrl->ul_harq_processes[sched_ctrl->sched_pusch.ul_harq_pid];
       cur_harq->sched_pusch.frame = sched_ctrl->sched_pusch.frame;
       cur_harq->sched_pusch.slot = sched_ctrl->sched_pusch.slot;
-      /* Get previous PSUCH filed info */
+      /* Get previous PSUCH field info */
       sched_ctrl->sched_pusch = cur_harq->sched_pusch;
       NR_sched_pusch_t *sched_pusch = &sched_ctrl->sched_pusch;
       LOG_D(MAC, "%4d.%2d Allocate UL retransmission UE %d/RNTI %04x sched %4d.%2d (%d RBs)\n",
@@ -592,6 +582,7 @@ void pf_ul(module_id_t module_id,
             sched_pusch->frame, sched_pusch->slot,
             sched_pusch->rbSize);
 
+      /* Check the resource is enough for retransmission */
       while (rbStart < bwpSize && !rballoc_mask[rbStart]) rbStart++;
       if (rbStart + sched_pusch->rbSize >= bwpSize) {
         LOG_W(MAC, "cannot allocate UL data for UE %d/RNTI %04x: no resources\n",
@@ -599,8 +590,20 @@ void pf_ul(module_id_t module_id,
         return;
       }
       sched_pusch->rbStart = rbStart;
+
       /* no need to recompute the TBS, it will be the same */
 
+      /* Find free CCE */
+      bool freeCCE = find_free_CCE(module_id, slot, UE_id);
+      if (!freeCCE) {
+        LOG_D(MAC, "%4d.%2d no free CCE for retransmission UL DCI UE %04x\n", frame, slot, UE_info->rnti[UE_id]);
+        continue;
+      }
+      /* reduce max_num_ue once we are sure UE can be allocated, i.e., has CCE */
+      max_num_ue--;
+      if (max_num_ue < 0)
+        return;
+
       /* Mark the corresponding RBs as used */
       n_rb_sched -= sched_pusch->rbSize;
       for (int rb = 0; rb < sched_ctrl->sched_pusch.rbSize; rb++)