transmit the packet with a second sequence number and mark the packet as a new packet when a transmission number of the packet with the first sequence number reaches a configured maximum number of transmissions step 306 end according to the process 30 in an harq process when a packet reaches the configured maximum number of transmissions and is not received successfully the transmitter marks the packet as a new packet and retransmits it to the receiver so as to flush soft buffer of the receiver in other words retransmissions in the present invention do not rely on upper layer or outer arq so that transmission delay is reduced and transmission efficiency can be enhanced preferably the transmitter can count the transmission number of the packet with a counter and reset the counter when the packet is marked as a new packet besides the second sequence number of the retransmitted packet can be equal to or different from the first sequence number of the original packet therefore in the harq process if the counter counting the transmission number of a packet reaches the maximum number of transmissions stored in harq profile and the transmitter does not receive any acknowledgement signal corresponding to the packet the transmitter will keep the sequence number of the packet or set another sequence number for the packet mark the packet as a new packet and retransmit the packet to the receiver when the receiver receives the packet marked as the new packet the receiver flushes buffer before soft combination so as to avoid the potential problems that the buffer may contain data of a different packet erroneously therefore the present invention can retransmit packets.