The base station 20, wherein each of {HEAD ~ the plurality} of {TAIL ~ mobile stations} has a corresponding reference signal 
The base station 20 , wherein each of { HEAD ~ the plurality } of { TAIL ~ mobile stations } has a corresponding reference signal
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH