Abstract: A wireless transceiver apparatus (201, 203) and a method of operation in an Automatic Repeat Request (ARQ) mode is disclosed. On the transmitter side a packet of data (113) is fragmented into a series of sequential data blocks and each data block is assigned a block sequence number (601). At least a first data block of the series of sequential data blocks is sent to the receiver (603), and also a first block sequence number corresponding to the first data block. An acknowledgment timer is set (605) specifying a time interval in which to receive an acknowledgment message from the remote transceiver. If the acknowledgment timer has timed out, the transmitter side sends a discard message (607) to the receiver specifying at least a second block sequence number corresponding to at least a second data block, and specifying that said second data block is to be discarded.