ENB notifies Slot format to UE using several parameters such as:
pattern2 (TDD-UL-DL-Pattern OPTIONAL)
where, TDD-UL-DL-Pattern includes:
dl-UL-TransmissionPeriodicity : Periodicity of the DL-UL pattern
nrofDownlinkSlots : Number of consecutive full DL slots at the beginning of each DL-UL pattern
nrofDownlinkSymbols : Number of consecutive DL symbols in the beginning of the slot following the last full DL slot
nrofUplinkSlots : Number of consecutive full UL slots at the end of each DL-UL pattern
nrofUplinkSymbols : Number of consecutive UL symbols in the end of the slot preceding the first full UL slot
If if TDD-UL-DL-ConfigCommon is not configured, then the UE determines if each of the slot is uplink or downlink and the symbol allocation within each of the slot purely by DCIs as stated in 38.213-11.1 Slot configuration.
As a special case, DL Preemption or Puncturing Indication (PI) or Dynamic Slot Format Indication (SFI) is used to indicate eMBB UEs when URLLC data is transmitted.