In a communication system using closed loop multiple input multiple output, beam forming information may be fed back from a receiver to a transmitter sequentially over a number of frames. The laser light is generated from an oscillator, passes through an attenuator that includes a filter, and passes through an optical system after passing through the attenuator. A network of MOS transistor switches with a small footprint adjusts the resistance of the input voltage circuit in a way to insure consistent resistance and low stray capacitance. Alternatively, every swinging movement necessary for zigzagging the embroidering material may be set by the swinging angle without the guide lever being caused to swing relative to the rotary cylinder. Said water swellable layer is made of an expanded polymeric material in which a water swellable material preferably in the form of powder, is embedded. The building element has internal through cavities for housing of operative connections of distribution systems and the like, arranged according to an array parallel to said plane major face, which is formed with references for identification from outside of each through cavity.