estimating {HEAD ~ one or more network conditions} of a network using a comparison between {TAIL ~ the certain time} and the acquired timestamp 
estimating { HEAD ~ one or more network conditions } of a network using a comparison between { TAIL ~ the certain time } and the acquired timestamp
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH