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