This is due to the fact that {TAIL ~ the minimum ISI} makes {HEAD ~ the symbols} unintelligible from the digital point of view, due to the increased intrinsic similarity between them 
This is due to the fact that { TAIL ~ the minimum ISI } makes { HEAD ~ the symbols } unintelligible from the digital point of view , due to the increased intrinsic similarity between them
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH