diff --git a/openair1/SIMULATION/NR_PHY/dlsim.c b/openair1/SIMULATION/NR_PHY/dlsim.c
index aca129623e..95892d669b 100644
--- a/openair1/SIMULATION/NR_PHY/dlsim.c
+++ b/openair1/SIMULATION/NR_PHY/dlsim.c
@@ -591,13 +591,15 @@ int main(int argc, char **argv)
   
   uint64_t mask = 0x0;
   uint16_t num_rbs=24;
-  uint16_t rb_offset=0;
+  uint16_t rb_offset=gNB->pdcch_vars.dci_alloc[0].pdcch_params.rb_offset;
   uint16_t cell_id=0;
   uint16_t num_symbols=2;
   for(i=0; i<(num_rbs/6); ++i){   //  38.331 Each bit corresponds a group of 6 RBs
     mask = mask >> 1;
     mask = mask | 0x100000000000;
   }
+  uint16_t rb_offset_count = rb_offset/6;
+  mask = mask >> rb_offset_count;
   dl_config->dl_config_list[0].dci_config_pdu.dci_config_rel15.coreset.frequency_domain_resource = mask;
   dl_config->dl_config_list[0].dci_config_pdu.dci_config_rel15.coreset.rb_offset = rb_offset;  //  additional parameter other than coreset