Thus, any occurrence of {TAIL ~ a combination} of sequences that causes large interference may reduce {HEAD ~ the communications quality} 
Thus , any occurrence of { TAIL ~ a combination } of sequences that causes large interference may reduce { HEAD ~ the communications quality }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD