identification information of the first (theoretically) transmitted data packet among the first data packets continuously transmitted, for example, the identification information includes: the lowest sequence number of the data packet successfully received in order, the lowest sequence number of the data packet unsuccessfully received in order, the lowest sequence number of the retransmission data packet unsuccessfully received in order. For example, taking continuously successfully received data packets (that is, a group of successfully received data packets with continuous sequence numbers) as an example, according to the sequence number of the data packet, if the sequence numbers of successfully received data packets are data packet 1, data packet 2, and data packet 3, the identification information is the sequence number of data packet 1.
identification information of the last (theoretically) transmitted data packet among the first data packets continuously transmitted, for example, the identification information includes the largest sequence number among data packets sequentially lost, the largest sequence number of the data packet successfully received in order, and the largest sequence number of the retransmission data packet successfully received in order. Taking data packets which are lost during transmission and have continuous sequence numbers as an example, the identification information may be the largest sequence number among a group of lost data packets.
In order to better understand and explain the various information that may be carried in the above first message, the following uplink data packet is taken as an example to explain various information that may be included in the above first message.