Mobile devices, mobile systems and operating methods thereof

An operating method of a second mobile device, the operating method comprising:

• transmitting a host request to a first mobile device through a connection terminal in a first power line communication (PLC) mode, the first mobile device and the second mobile device respectively modulating signals according to different modulation schemes in the first PLC mode, the different modulation schemes including current modulation and voltage modulation;
• receiving a client response from the first mobile device as a response to the host request;
• changing a PLC mode between the first mobile device and the second mobile device from the first PLC mode to a second PLC mode including increasing an impedance of a signal line based on the client response, the signal line being connected to the connection terminal, and the first mobile device and the second mobile device both modulating signals according to a common modulation scheme in the second PLC mode;
• transmitting data to the first mobile device in the second PLC mode;
• and
• changing the PLC mode from the second PLC mode to the first PLC mode including decreasing the impedance of the signal line based on completion of the transmitting the data.

A mobile system, comprising:

• a first mobile device;
• and
• a second mobile device, the first mobile device and the second mobile device being configured to transfer power and data with each other using power line communication (PLC), wherein
• the first mobile device includes
• a first connection terminal configured to electrically connect to the second mobile device,
• a first variable impedance device connected to the first connection terminal, and
• first processing circuitry configured to
• send a client response to the second mobile device in response to receiving a host request from the second mobile device,
• change a first PLC mode between the first mobile device and the second mobile device from a low-speed PLC mode to a high-speed PLC mode in response to sending the client response, the first mobile device and the second mobile device respectively modulating signals according to different modulation schemes in the low-speed PLC mode, the different modulation schemes including current modulation and voltage modulation, and the first mobile device and the second mobile device both modulating signals according to a common modulation scheme in the high-speed PLC mode, and
• control an impedance of the first variable impedance device according to the first PLC mode, and
• the second mobile device includes
• a second connection terminal configured to electrically connect to the first mobile device,
• a second variable impedance device connected to the second connection terminal, and
• second processing circuitry configured to
• receive the client response from the first mobile device in response to sending the host request,
• change a second PLC mode from the low-speed PLC mode to the high-speed PLC mode in response to receiving the client response, and
• control an impedance of the second variable impedance device according to the second PLC mode.

A first mobile device comprising:

• a connection terminal configured to electrically connect to a second mobile device;
• a variable impedance device connected to the connection terminal, the variable impedance device configured to vary an impedance;
• processing circuitry configured to
• send a client response to the second mobile device in response to receiving a host request from the second mobile device,
• change a power line communication (PLC) mode between the first mobile device and the second mobile device from a first PLC mode to a second PLC mode in response to sending the client response, the first mobile device and the second mobile device respectively modulating signals according to different modulation schemes in the first PLC mode, the different modulation schemes including current modulation and voltage modulation, and the first mobile device and the second mobile device both modulating signals according to a common modulation scheme in the second PLC mode, and
• control the impedance of the variable impedance device according to the PLC mode;
• and
• a PLC modem configured to receive power from the second mobile device or communicate data with the second mobile device based on the PLC mode.