For each received symbol, the receiver determines which of {HEAD ~ a plurality} of {TAIL ~ phase} sectors the phase angle lies in 
of
For each received symbol , the receiver determines which of { HEAD ~ a plurality } of { TAIL ~ phase } sectors the phase angle lies in
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH