To solve the problems wherein when a certain sensor transmits a detection signal, a large number of unwanted sensors temporarily wake up, and power consumption is increased because all the sensors in a range where radio waves reach temporarily wake up to determine whether a signal has been transmitted to themselves, and that useless transmission causes an increase in power consumption because each of sensors asynchronously performs intermittent reception and transmission operations and communication must be continued until a communication party wakes up when a certain sensor transmits a detection signal, in a sensor network system according to a conventional technique.
A sensor network system is provided with a means for limiting the number of communication parties, which has a function of adjusting the strength of a radio wave transmitted from a searching means for searching a sensor to be a communication party, thereby limiting the number of communicable sensors 1. The sensors are each synchronized with time so as to perform time-synchronized intermittent reception operation to repeat wakeup and sleep at the same time.
Tadahiko Inaba
Kanako Murakami
Nakatsuru Kazutaka
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