| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize a low interference for multiple accesses by means of a non-synchronized locator transceiver through the use of frequency hopping which is required for the use of a common band by transmitting a data packet after a prescribed time during prescribed-time waiting, when a communication channel is still idle. SOLUTION: Personal alarm(PAD) 100b starts access of a communication channel so as to determine whether a data packet is ready to be transmitted or not and the channel is detected in order to determine whether it is busy or not in an affirmation. When the channel is in an idle state, a device waits for a specified interval (priority order-delay time) before testing the idle state again. When the channel finds the idle state, a message is transmitted. That is, the device executes transmission onto the channel only when the channel is still in the idle state after the priority order-delay interval.</p> |
