diff --git a/openair1/SIMULATION/NR_PHY/dlsim.c b/openair1/SIMULATION/NR_PHY/dlsim.c
index a4ee4c8c6e..be20b779db 100644
--- a/openair1/SIMULATION/NR_PHY/dlsim.c
+++ b/openair1/SIMULATION/NR_PHY/dlsim.c
@@ -150,6 +150,42 @@ int is_x2ap_enabled(void)
 openair0_config_t openair0_cfg[MAX_CARDS];
 
 
+/* specific dlsim DL preprocessor: uses rbStart/rbSize/mcs from command line of
+   dlsim, does not search for CCE/PUCCH occasion but simply sets to 0 */
+int g_mcsIndex = -1, g_rbStart = -1, g_rbSize = -1;
+void nr_dlsim_preprocessor(module_id_t module_id,
+                           frame_t frame,
+                           sub_frame_t slot,
+                           int num_slots_per_tdd) {
+  NR_UE_info_t *UE_info = &RC.nrmac[module_id]->UE_info;
+  AssertFatal(UE_info->num_UEs == 1, "can have only a single UE\n");
+  NR_UE_sched_ctrl_t *sched_ctrl = &UE_info->UE_sched_ctrl[0];
+
+  /* manually set free CCE to 0 */
+  const int target_ss = NR_SearchSpace__searchSpaceType_PR_ue_Specific;
+  sched_ctrl->search_space = get_searchspace(sched_ctrl->active_bwp, target_ss);
+  uint8_t nr_of_candidates;
+  find_aggregation_candidates(&sched_ctrl->aggregation_level,
+                              &nr_of_candidates,
+                              sched_ctrl->search_space);
+  sched_ctrl->coreset = get_coreset(
+      sched_ctrl->active_bwp, sched_ctrl->search_space, 1 /* dedicated */);
+  sched_ctrl->cce_index = 0;
+
+  /* set "any" value for PUCCH (simulator evaluates PDSCH only) */
+  sched_ctrl->pucch_sched_idx = 0;
+  sched_ctrl->pucch_occ_idx = 0;
+
+  sched_ctrl->rbStart = g_rbStart;
+  sched_ctrl->rbSize = g_rbSize;
+  sched_ctrl->mcs = g_mcsIndex;
+  sched_ctrl->time_domain_allocation = 2;
+  sched_ctrl->mcsTableIdx = 0;
+  AssertFatal(sched_ctrl->rbStart >= 0, "invalid rbStart %d\n", sched_ctrl->rbStart);
+  AssertFatal(sched_ctrl->rbSize > 0, "invalid rbSize %d\n", sched_ctrl->rbSize);
+  AssertFatal(sched_ctrl->mcs >= 0, "invalid sched_ctrl->mcs %d\n", sched_ctrl->mcs);
+  sched_ctrl->numDmrsCdmGrpsNoData = 1;
+}
 
 
 int main(int argc, char **argv)
@@ -197,8 +233,6 @@ int main(int argc, char **argv)
   //double pbch_sinr;
   //int pbch_tx_ant;
   int N_RB_DL=106,mu=1;
-  nfapi_nr_dl_tti_pdsch_pdu_rel15_t dlsch_config;
-  NR_sched_pucch pucch_sched;
 
   //unsigned char frame_type = 0;
 
@@ -227,7 +261,6 @@ int main(int argc, char **argv)
 
   randominit(0);
 
-  int mcsIndex_set=0,rbStart_set=0,rbSize_set=0;
   int print_perf             = 0;
 
   FILE *scg_fd=NULL;
@@ -393,18 +426,15 @@ int main(int argc, char **argv)
 
 
     case 'a':
-      dlsch_config.rbStart = atoi(optarg);
-      rbStart_set=1;
+      g_rbStart = atoi(optarg);
       break;
 
     case 'b':
-      dlsch_config.rbSize = atoi(optarg);
-      rbSize_set=1;
+      g_rbSize = atoi(optarg);
       break;
 
     case 'e':
-      dlsch_config.mcsIndex[0] = atoi(optarg);
-      mcsIndex_set=1;
+      g_mcsIndex = atoi(optarg);
       break;
 
     case 'm':
@@ -483,6 +513,7 @@ int main(int argc, char **argv)
     RC.nb_nr_mac_CC[i] = 1;
   mac_top_init_gNB();
   gNB_mac = RC.nrmac[0];
+  gNB_mac->pre_processor_dl = nr_dlsim_preprocessor;
   gNB_RRC_INST rrc;
   memset((void*)&rrc,0,sizeof(rrc));
 
@@ -560,6 +591,12 @@ int main(int argc, char **argv)
   //  nr_phy_config_request_sim(gNB,N_RB_DL,N_RB_DL,mu,Nid_cell,SSB_positions);
   // call MAC to configure common parameters
 
+  /* rrc_mac_config_req_gNB() has created one user, so set the scheduling
+   * parameters from command line in global variables that will be picked up by
+   * scheduling preprocessor */
+  if (g_mcsIndex < 0) g_mcsIndex = 9;
+  if (g_rbStart < 0) g_rbStart=0;
+  if (g_rbSize < 0) g_rbSize = N_RB_DL - g_rbStart;
 
   double fs,bw;
 
@@ -687,11 +724,6 @@ int main(int argc, char **argv)
   AssertFatal(input_fd==NULL,"Not ready for input signal file\n");
   gNB->pbch_configured = 1;
   gNB->ssb_pdu.ssb_pdu_rel15.bchPayload=0x001234;
-  
-  if (mcsIndex_set==0) dlsch_config.mcsIndex[0]=9;
-  
-  if (rbStart_set==0) dlsch_config.rbStart=0;
-  if (rbSize_set==0) dlsch_config.rbSize=N_RB_DL-dlsch_config.rbStart;
 
   //Configure UE
   rrc.carrier.MIB = (uint8_t*) malloc(4);
@@ -788,8 +820,14 @@ int main(int argc, char **argv)
         for (int i=0; i<MAX_NUM_CORESET; i++)
           gNB_mac->UE_info.num_pdcch_cand[0][i] = 0;
       
-        if (css_flag == 0) nr_schedule_uss_dlsch_phytest(0,frame,slot,&pucch_sched,&dlsch_config);
-        else               nr_schedule_css_dlsch_phytest(0,frame,slot);
+        if (css_flag == 0) {
+          const uint8_t slots_per_frame[5] = {10, 20, 40, 80, 160};
+          const NR_TDD_UL_DL_Pattern_t *tdd_pattern = &scc->tdd_UL_DL_ConfigurationCommon->pattern1;
+          const int num_slots_per_tdd = slots_per_frame[*scc->ssbSubcarrierSpacing] >> (7 - tdd_pattern->dl_UL_TransmissionPeriodicity);
+          nr_schedule_ue_spec(0, frame, slot, num_slots_per_tdd);
+        } else {
+          nr_schedule_css_dlsch_phytest(0,frame,slot);
+        }
         Sched_INFO.module_id = 0;
         Sched_INFO.CC_id     = 0;
         Sched_INFO.frame     = frame;
@@ -986,7 +1024,7 @@ int main(int argc, char **argv)
 
     if (print_perf==1) {
       printf("\ngNB TX function statistics (per %d us slot, NPRB %d, mcs %d, TBS %d, Kr %d (Zc %d))\n",
-	     1000>>*scc->ssbSubcarrierSpacing,dlsch_config.rbSize,dlsch_config.mcsIndex[0],
+	     1000>>*scc->ssbSubcarrierSpacing, g_rbSize, g_mcsIndex,
 	     gNB->dlsch[0][0]->harq_processes[0]->pdsch_pdu.pdsch_pdu_rel15.TBSize[0]<<3,
 	     gNB->dlsch[0][0]->harq_processes[0]->K,
 	     gNB->dlsch[0][0]->harq_processes[0]->K/((gNB->dlsch[0][0]->harq_processes[0]->pdsch_pdu.pdsch_pdu_rel15.TBSize[0]<<3)>3824?22:10));