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