Patent ID: 8320289
Filing Date: 2012-11-27
Classification: G08B,H04W,Y02D

Abstract:
1. A wireless communication system comprising: a plurality of wireless terminals; and a synchronization device, wherein each of said wireless terminals includes a power supply unit configured to accommodate a battery, a wireless transmitter, a wireless receiver, a timer configured to output an activating signal at a predetermined interval, a control unit, and a synchronization unit, said control unit including an operation control module, a reception control module, and a transmission control module, said operation control module being configured to keep said reception control module operating and deactivate said transmission control module unless a predetermined event occurs, and to activate said transmission control module and deactivate said reception control module in response to occurrence of the event, said reception control module being configured to, upon receiving said activation signal from said timer, supply electrical power from said power supply unit to said wireless receiver for activation thereof, and to control the same wireless receiver in a manner to deactivate said wireless receiver unless said wireless receiver receives a predetermined wireless signal before a predetermined waiting time elapses after said wireless receiver is activated, said transmission control module being configured to supply electrical power from said power supply unit to said wireless transmitter for intermittent activation thereof, and to control said wireless transmitter in a manner to transmit an event notification signal defined as a wireless signal including a message corresponding to said event in a transmission period in which said wireless transmitter operates, said synchronization device being configured to transmit, to the plurality of said wireless terminals, a synchronization signal defined as a wireless signal announcing a reference time, said synchronization signal comprising a plurality of reference signals which are arranged in a time axis, each of said reference signals including a reference data indicative of a relation between the corresponding reference signal and said reference time, said synchronization unit including a reference time calculation module, and a timer control module, said reference time calculation module being configured to refer to said reference data obtained from an earliest reference signal defined as said reference signal which said wireless receiver receives primarily and a reception time at which said wireless receiver receives said earliest reference signal, when said wireless receiver receives said synchronization signal, and determine the reference time, said timer control module being configured to perform a synchronization processing of controlling said timer such that said activation signal is output after a predetermined time elapses from said reference time calculated by said reference time calculation module, and said transmission control module being configured to control said wireless transmitter to transmit said event notification signal during said transmission period including a time period of receiving said activation signal from said timer.