A display device (160, 210) comprising: a display; a memory storing at least one instruction; a communicator configured to communicate with a mobile device (152, 360) via at least one wireless network comprising a Bluetooth low energy, BLE, communication network; and a controller comprising at least one processor configured to execute the at least one instruction stored in the memory, characterized in that: the at least one processor is further configured to execute the at least one instruction to: while the display device (160, 210) operates in a normal mode, execute an ambient service which provides a meaningful screen image comprising at least one of a painting, a photo, and a clock on the display; in response to BLE identification information, for identifying the mobile device (152, 360) connected via the BLE communication network, being received from the mobile device while the display device operates in the normal mode in which the ambient service is being executed, determine whether the registered mobile device is presented based on whether information corresponding to the BLE identification information received from the mobile device (152, 360) is stored in the memory; in response to the registered mobile device is presented based on a result of the determination, maintain the execution of the ambient service; and in response to the registered mobile device is not presented based on a result of the determination, control the ambient service to be ended and control the display device to be in a sleep mode in which the ambient service is stopped and the display is turned off, and the communicator is further configured to:after the sleep mode is started, in response to the BLE identification information being received from the mobile device, determine whether to wake up the controller based on whether information corresponding to the BLE identification information received from the mobile device (152, 360) is stored in the communicator. a display; a memory storing at least one instruction; a communicator configured to communicate with a mobile device (152, 360) via at least one wireless network comprising a Bluetooth low energy, BLE, communication network; and a controller comprising at least one processor configured to execute the at least one instruction stored in the memory, characterized in that: the at least one processor is further configured to execute the at least one instruction to: while the display device (160, 210) operates in a normal mode, execute an ambient service which provides a meaningful screen image comprising at least one of a painting, a photo, and a clock on the display; in response to BLE identification information, for identifying the mobile device (152, 360) connected via the BLE communication network, being received from the mobile device while the display device operates in the normal mode in which the ambient service is being executed, determine whether the registered mobile device is presented based on whether information corresponding to the BLE identification information received from the mobile device (152, 360) is stored in the memory; in response to the registered mobile device is presented based on a result of the determination, maintain the execution of the ambient service; and in response to the registered mobile device is not presented based on a result of the determination, control the ambient service to be ended and control the display device to be in a sleep mode in which the ambient service is stopped and the display is turned off, and the communicator is further configured to:after the sleep mode is started, in response to the BLE identification information being received from the mobile device, determine whether to wake up the controller based on whether information corresponding to the BLE identification information received from the mobile device (152, 360) is stored in the communicator. while the display device (160, 210) operates in a normal mode, execute an ambient service which provides a meaningful screen image comprising at least one of a painting, a photo, and a clock on the display; in response to BLE identification information, for identifying the mobile device (152, 360) connected via the BLE communication network, being received from the mobile device while the display device operates in the normal mode in which the ambient service is being executed, determine whether the registered mobile device is presented based on whether information corresponding to the BLE identification information received from the mobile device (152, 360) is stored in the memory; in response to the registered mobile device is presented based on a result of the determination, maintain the execution of the ambient service; and in response to the registered mobile device is not presented based on a result of the determination, control the ambient service to be ended and control the display device to be in a sleep mode in which the ambient service is stopped and the display is turned off, and the communicator is further configured to:after the sleep mode is started, in response to the BLE identification information being received from the mobile device, determine whether to wake up the controller based on whether information corresponding to the BLE identification information received from the mobile device (152, 360) is stored in the communicator.