on errors or intended for another UE and in either case the device ignores that PDCCH transmission. The gNB can only address a UE, if the corresponding control information is transmitted on a PDCCH formed by the CCEs in one of the UE's search spaces. Therefore, for efficient utilization of the CCEs in the system, the UE should be associated with different search spaces. Each device in the system can be configured with one or more UE-specific search spaces. Since a UE-specific search space is typically smaller than the number of PDCCHs that the network can transmit at the corresponding aggregation level, there must be a mechanism to deter- mine a set of CCEs in UE-specific search space. One option is to allow the network to figure the UE-specific search space for each device, in the same way that CORESETs are configured. However, this would require explicit signaling exchange with each device and possibly reconfiguration at handover. Instead, the UE-specific search spaces for PDCCH are defined without explicit signaling and based on the device unique identity in the cell in the connected mode, that is, C-RNTI. Furthermore, the set of CCEs that the device should mon- itor at a certain aggregation level varies as a function of time to avoid two devices con- stantly blocking each other. If they collide at one time instant, they are not likely to collide at the next time instant. In each of these search spaces, the UE attempts to decode the PDCCHs using the UE-specific C-RNTI. There is also information intended for a group of UEs in the cell. These messages are scheduled with different predefined RNTIs, for exam- ple, SI-RNTI for scheduling system information, P-RNTI for transmission of a paging mes- sage, RA-RNTI for transmission of the random-access response, TPC-RNTI for uplink power control, INT-RNTI for preemption indication, and SFI-RNTI for slot format configu- ration. As part of random-access procedure, it is necessary to transmit information to a device before it is assigned a unique identity. These types of 