A method and apparatus for providing timing operations in time division duplex (TDD) communications are disclosed herein. A wireless transmit/receive unit (WTRU) comprising a transmitter and a processor may be configured to receive time division duplex (TDD) configuration information and a grant for uplink transmission. The grant may indicate a hybrid automatic repeat request (HARQ) process. The WTRU may be configured to determine time intervals for downlink communication, uplink communication and uplink and downlink communication based on the TDD configuration. The transmitter may be configured to transmit using the indicated HARQ process in a time interval for uplink and downlink communication.