Apparatus for checking identification signal and method thereof

An identification signal checking method of an identification signal checking apparatus comprising a first device having a first wireless transmitting and receiving unit, a first signal processing unit and a first memory unit for storing an identification signal, and a second device having a second wireless transmitting and receiving unit, a second signal processing unit, and a second memory unit for storing an identification signal comprising the steps of:

• transmitting a communication request signal from said first device to said second device;
• transmitting a communication permission signal from said second device to said first device in response to said communication request signal, in which said second device begins transmitting said communication permission signal after a first predetermined period following reception of said communication request signal and completes transmission of said communication permission signal within a second predetermined time period after said first predetermined time period,
• transmitting, upon reception of said communication permission signal, the identification signal stored in said first memory unit from said first device to said second device;
• and
• checking in said second device whether or not the transmitted identification signal coincides with the identification signal stored in said second memory unit.