A user equipment is configured to connect to a base station (BS) over a shared channel subject to channel access operations. The UE receives a first configuration for a BS-initiated fixed frame period (FFP) (BS-FFP) and a second configuration for a UE-initiated FFP (UE-FFP), determines that no downlink (DL) transmissions are detected during a predefined time of the BS-FFP and determines that at least one condition associated with an uplink (UL) transmission is satisfied. When no downlink (DL) transmissions are detected during the predefined time of the BS-FFP and the at least one condition is satisfied, the UE performs a UE-initiated channel access operation. When the UE-initiated channel access operation is successful, the UE performs the UL transmission during the UE-FFP.