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