Thus high priority services can pre empt {TAIL ~ the usage} of wireless resources by {HEAD ~ low priority services} 
Thus high priority services can pre empt { TAIL ~ the usage } of wireless resources by { HEAD ~ low priority services }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD