An exercise apparatus includes a frame for residing on a horizontal surface, a pair of arm-supporting members for supporting the user’s arms and a pair of leg-supporting members for supporting the user’s legs. Each unit has a front door and a back door. In a display device including a display element between a pair of light transmitting substrates, a layer including stacked polarizers is each provided on an outer side of the substrates. Responsively to the downlink signal, during a second frame subsequent to the first frame, the mobile unit transmits the uplink signal both in the respective time slot and in the reserved time slot so as to carry the first uplink data and second uplink data over the air to the base station. Furthermore, only those base stations which are associated with the multicast IP address will act on the message, all other base stations may ignore it.