A method for transmitting packets classified according to QoS requirement from a transmitting node to a receiving node is provided, the transmitting node being configured to select sequentially a QoS class, to divide a queued packet to be transmitted, which belongs to the selected class, into a plurality of predetermined data units, to transmit one of the predetermined data units, and to apply a transmitter-side retransmission control process to the data unit to be transmitted when the selected class is a QoS class specified for data type packets, and the receiving node being configured to receive sequentially the data units transmitted from the transmitting node, to assemble a plurality of received data units to restore an original packet for each QoS class, and to apply a receiver-side retransmission control process to the received data units when the received data unit belongs to one of the data type QoS classes.
