A wireless communication method and apparatus for selecting and reselecting cells used by a wireless transmitreceive unit in a wireless multi-cell communication system. Other embodiments refer to a substantially 400 Gbs optical receiver, other optical transceivers that operate at substantially 100 Gbs and beyond, and related apparatus and methods. Between the adjusting seats inside the head rail is situated a positioning seat with a set of guide sliding members accommodated at both sides thereof in linking movement with a linkage actuating plate controlled by an operational cord that is wound and suspended from a second pulley seat adapted at the other end of the head rail.