External device for mobile communication terminal and NFC method using the same

An external device for a mobile communication terminal, said external device comprising:

• a serial communication unit connectable to the mobile communication terminal through a connector;
• an antenna;
• a Near Field Communication (NFC) unit for communicating with the mobile communication terminal through the serial communication unit and communicating with an outside device via non-contact NFC through the antenna;
• a smart card unit for communicating with the NFC unit;
• a Universal Serial Bus (USB) communication unit, other than the serial communication unit;
• and
• a protocol matching unit coupled between the NFC unit and the smart card unit;
• wherein
• the external device is configured to detect whether the external device is connected to one of
• (i) the mobile communication terminal through the connector of the serial communication unit, and
• (ii) to a USB host device via the USB communication unit;
• the NFC unit is configured to, in response to a determination that the external device is connected to the mobile communication terminal,
• communicate with the mobile communication terminal via a serial communication protocol,
• communicate with the outside device by transmitting/receiving signals through the antenna via non-contact NFC, and
• communicate with the smart card unit, wherein the protocol matching unit is configured to perform protocol conversion between the NFC unit and the smart card unit;
• and
• the external device is configured to, in response to a determination that the external device is connected to the USB host device, serve as a USB slave and communicate with the USB host device via a USB interface.