This increased similarity between the constellation symbols of a digital system that uses {HEAD ~ a denser constellation} turns into {TAIL ~ a serious problem} for the system performance when the channel is dispersive 
This increased similarity between the constellation symbols of a digital system that uses { HEAD ~ a denser constellation } turns into { TAIL ~ a serious problem } for the system performance when the channel is dispersive
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH