In {TAIL ~ technical terms}, {HEAD ~ the distance} that differs the symbols from each other becomes shorter, which hampers the identification of the symbol effectively received 
In
In { TAIL ~ technical terms } , { HEAD ~ the distance } that differs the symbols from each other becomes shorter , which hampers the identification of the symbol effectively received
REL 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 OTH OTH OTH