Abstract text

A transmission source device transmits a test signal to a transmission destination device and a transmitting device by wireless communication. The transmission destination device and the transmitting device add to a received test signal an identification number thereof and a receiving time and return the data-added test signal to the transmission source device. The transmission source device determines a communication route with a shortest communication time based on the received data-added test signal. The transmission source device transmits logic-circuit update data to the transmission destination device via the determined communication route.