Data retransmission method and communications apparatus

A data retransmission method, comprising:

• starting, by a transmit end, a timer before transmitting new data to a receive end, wherein a preset value of the timer is a maximum transmission latency corresponding to a service type of the new data;
• transmitting, by the transmit end, the new data to the receive end;
• determining, by the transmit end, whether a current time of transmission exceeds a maximum transmission quantity;
• sending, by the transmit end, retransmission data to the receive end when the timer does not expire and there is data to be retransmitted, wherein the retransmission data is a part or all of the data wherein when the transmit end sends the new data by using an uplink transmission time-frequency resource prestored by the transmit end and allocated by the receive end to the transmit end, wherein calculating the maximum transmission quantity is based on the following:
• N_MAX=Floor (Total_Delay_MAX/Single_Tx_Delay), wherein
• Floor( ) indicates rounding down;
• Total_Delay_MAX represents the maximum transmission latency corresponding to the service type of the data;
• and
• Single_Tx_Delay represents a single transmission latency of a service corresponding to the data;
• stopping sending, by the transmit end, the retransmission data to the receive end when the timer does not expire and the current time of transmission exceeds the maximum transmission quantity;
• and
• stopping sending, by the transmit end, the retransmission data to the receive end when the timer expires;
• and, wherein sending, by the transmit end, the retransmission data to the receive end when the timer does not expire and data needs to be retransmitted comprises:
• stopping sending, by the transmit end, the retransmission data to the receive end when the timer does not expire and a remaining time of the timer is less than a time required by the receive end to receive and process the retransmission data.