A method and apparatus according to the present invention addresses and/or prevents lost protocol synchronization in HARQ systems caused by ACK/NACK errors. The embodiment detects lost synchronization errors for NDI-less retransmission protocols. Protocol synchronization errors are prevented by sending scheduling grants (SCH) on a packet by packet basis. The receiver sends a subsequent explicit scheduling grant to the transmitter based on an error evaluation of a received PDU. The transmitter will not send the next PDU unless it receives the subsequent explicit scheduling grant.
