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