A method for Time Division Duplex, TDD, operation by a wireless transmit/receive unit, WTRU, the method comprising: receiving a first TDD uplink UL/downlink DL reference configuration for a serving cell; receiving a second TDD UL/DL reference configuration for the serving cell; wherein the first and second TDD UL/DL reference configurations are separate and are received from a base station; said method being characterized by: determining whether a third TDD UL/DL reference configuration for the serving cell is received from the base station, wherein said third TDD UL/DL reference configuration is separate from the first and second TDD UL/DL reference configurations; using the first TDD UL/DL reference configuration for determining the timing of UL scheduling and UL Hybrid Automatic Repeat Request, HARQ, wherein said timing of UL scheduling comprises the timing of corresponding one or more UL transmissions by the WTRU to the base station; using the second TDD UL/DL reference configuration for determining the timing of DL HARQ; and determining a UL or DL direction for each subframe based on the third TDD UL/DL reference configuration on a condition that said third TDD UL/DL reference configuration is received; wherein on a condition that the determined direction for a subframe is DL, receiving from said base station, one or more DL transmissions in the subframe. receiving a first TDD uplink UL/downlink DL reference configuration for a serving cell; receiving a second TDD UL/DL reference configuration for the serving cell; wherein the first and second TDD UL/DL reference configurations are separate and are received from a base station; said method being characterized by: determining whether a third TDD UL/DL reference configuration for the serving cell is received from the base station, wherein said third TDD UL/DL reference configuration is separate from the first and second TDD UL/DL reference configurations; using the first TDD UL/DL reference configuration for determining the timing of UL scheduling and UL Hybrid Automatic Repeat Request, HARQ, wherein said timing of UL scheduling comprises the timing of corresponding one or more UL transmissions by the WTRU to the base station; using the second TDD UL/DL reference configuration for determining the timing of DL HARQ; and determining a UL or DL direction for each subframe based on the third TDD UL/DL reference configuration on a condition that said third TDD UL/DL reference configuration is received; wherein on a condition that the determined direction for a subframe is DL, receiving from said base station, one or more DL transmissions in the subframe. determining whether a third TDD UL/DL reference configuration for the serving cell is received from the base station, wherein said third TDD UL/DL reference configuration is separate from the first and second TDD UL/DL reference configurations; using the first TDD UL/DL reference configuration for determining the timing of UL scheduling and UL Hybrid Automatic Repeat Request, HARQ, wherein said timing of UL scheduling comprises the timing of corresponding one or more UL transmissions by the WTRU to the base station; using the second TDD UL/DL reference configuration for determining the timing of DL HARQ; and determining a UL or DL direction for each subframe based on the third TDD UL/DL reference configuration on a condition that said third TDD UL/DL reference configuration is received; wherein on a condition that the determined direction for a subframe is DL, receiving from said base station, one or more DL transmissions in the subframe.