User communication device executing standby mode, operating method thereof, and human body communication system including the same

A method of operating of a human body communication system which includes a user communication device, another user communication device and a stationary communication device communicating with each other over a first human body communication channel, the method comprising:

• transmitting, by the stationary communication device, a wakeup signal to the user communication device over the first human body communication channel, wherein the wakeup signal has a frequency in a low frequency band;
• switching, by the user communication device, from a standby mode to a wakeup mode in response to the wakeup signal;
• and
• transmitting, by the stationary communication device, a data signal to the user communication device over the first human body communication channel during the wakeup mode of the user communication device,
• wherein the first human body communication channel is provided by a body of a user of the user communication device;
• transmitting, by the user communication device, a standby signal requesting the other user communication device to set an operating mode of the other user communication device to the standby mode, during the wakeup mode;
• wherein the transmitting the standby signal requesting the other user communication device to set the operating mode of the other user communication device to the standby mode, during the wakeup mode includes:
• transmitting the standby signal to the other user communication device over a second human body communication channel during the wakeup mode, and
• wherein the second human body communication channel is provided by a body of a user of the other user communication device.

A user communication device comprising:

• a first electrode and a second electrode configured to contact a user;
• a receiver configured to receive a wakeup signal from a stationary communication device over a human body communication channel, based on that the first electrode contacts contacting the user;
• a processor configured to switch an operating mode from a standby mode to a wakeup mode based on the wakeup signal and to generate a standby signal indicating the standby mode;
• and
• a transmitter configured to transmit the standby signal to the stationary communication device over the human body communication channel, based on the second electrode contacting the user,
• wherein the processor enables communication for a low frequency band during the standby mode and enables the communication for the low frequency band and communication for a high frequency band during the wakeup mode,
• wherein the human body communication channel is provided by a body of the user;
• wherein the transmitter is further configured to transmit a standby signal requesting another user communication device to set an operating mode of the other user communication device to the standby mode, during the wakeup mode;
• wherein the transmitting the standby signal requesting the other user communication device to set the operating mode of the other user communication device to the standby mode, during the wakeup mode includes:
• transmitting the standby signal to the other user communication device over a second human body communication channel during the wakeup mode, and
• wherein the second human body communication channel is provided by a body of another user of the other user communication device.