receiving the transport control protocol acknowledgement from the terminal, wherein {HEAD ~ the received TCP acknowledgement} includes {TAIL ~ the sequence number} and corresponds to a certain time 
receiving the transport control protocol acknowledgement from the terminal , wherein { HEAD ~ the received TCP acknowledgement } includes { TAIL ~ the sequence number } and corresponds to a certain time
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH