switching the MIMO mode of {HEAD ~ the cell} to {TAIL ~ a non MIMO mode}; or 
switching the MIMO mode of { HEAD ~ the cell } to { TAIL ~ a non MIMO mode } ; or
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH