In a
wireless communication
system, slave units such as operation switches and the like are configured such that the higher the priority level of an information
signal to be transmitted from each slave unit is, the shorter a period t1 of a carrier sense to be performed before the transmission is set. Therefore, when the slave units attempt to transmit information signals of different priority levels by using the same time slot, one of the slave units whose information
signal to be transmitted is of the highest priority level is given the shortest carrier sense period t1 before the transmission of the information
signal, and therefore, can transmit the information signal at the earliest timing. Accordingly, by causing the slave unit which becomes able to transmit the information signal at the earliest timing to transmit the information signal, the information signal of the highest priority level can be transmitted at the earliest timing, while the other units are caused to sense, by carrier sense, the transmission, and put off transmission of their own information signals.