When the blocking interval is in effect for a particular station, that station cannot be selected for network access, so there can be {HEAD ~ no duplication} of {TAIL ~ packets} if the blocking interval is long enough 
When the blocking interval is in effect for a particular station , that station can not be selected for network access , so there can be { HEAD ~ no duplication } of { TAIL ~ packets } if the blocking interval is long enough
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH