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