ndicate FFP and channel occupancy time to the UE is being studied. FBE is a scheme where the transmit/receive frame structure is not directly demand-driven but has fixed tim- ing as opposed to LBE where the transmit/receive frame structure is not fixed in time but demand-driven. 884 Chapter 8 Dynamic and semi-statically configured downlink/uplink configuration can be used in NR- U. For example, some semi-static DL/UL assignments can be used to indicate downlink slots to the UE to receive the SS/PBCH blocks, and other slots can be assigned to the UE to transmit PRACH or granted uplink transmission. If gNB performs LBT successfully on the semi-statically configured downlink slot, it can dynamically override the flexible resource (s) through DCI format 2_0. Furthermore, the use of a flexible frame structure in NR-U can take advantage of MCOT. Multiple DL-to-UL switching points in the MCOT can be permit- ted to reduce the scheduling and feedback delay. However, more DL-to-UL switching points create more gaps to perform LBT upon each change of transmission direction which may result in resource wastage or channel loss during this time. Therefore, there is a tradeoff between fast switching and overhead for potential use cases. Because the MCOT duration is different for various channel access priorities and regional regulations, different maximum number of DL-to-UL switching points for each MCOT duration should be defined. In LTE- based LAA, the eNB can only start transmission at slot boundaries (symbol 0 or 7) with 15 kHz subcarrier spacing. The reservation signal is transmitted before the downlink trans- mission start position, that is, the slot boundary, to reserve the carrier and prevent other devices from occupying the frequency band, which is considered an overhead in LTE-based LAA system. Therefore, the overhead of reservation signal should be minimized. In NR-U, different slot types including slot and mini-slot (non-slot-based scheduling) can be utilized to minimize the reservation signal length. The gNB or UE s