Transmission cancellation method and transmission method

A transmission cancellation method, comprising:

• setting, when a broadcast message is received, a waiting time randomized within a predetermined interval;
• reserving, in a case where a message which is deemed to be the same as the received message is not received for a predetermined number of times until the waiting time passes, transmission of the message by broadcasting, but not reserving, in a case where the message is received for the predetermined number of times, the transmission of the message by broadcasting;
• and
• cancelling the transmission of the message of which transmission is reserved, in a case where the message of which transmission is reserved is broadcast with timing of a broadcast time slot and a message newer than the message of which transmission is reserved is received.

A transmission method, comprising:

• setting, when a broadcast message is received, a waiting time randomized within a predetermined interval;
• reserving, in a case where a message which is deemed to be the same as the received message is not received for a predetermined number of times until the waiting time passes, transmission of the message by broadcasting;
• but not reserving, in a case where the message is received for the predetermined number of times, the transmission of the message by broadcasting;
• and
• measuring, in a case where the message of which transmission is reserved is broadcast with timing of a broadcast time slot, the waiting time during the broadcast time slot.