Abstract: A system and method for continuing a communication link while maintaining visibility in visible light communication. A frame is transmitted by a sender for establishing a communication link before data transmission to a receiver by a sender. A receiver sends a response frame that reports on establishment of the communication link prior to data transmission by the sender. A data frame containing information is transmitted by the sender to the receiver. An acknowledgment frame is transmitted to the sender in response to the data frame. A disconnect frame is transmitted by the sender which is acknowledged by the receiver. A visible sequence is transmitted during a time period when the sender and the receiver do not transmit respective frames for communication to maintain visibility between two devices that may be communicating otherwise by, for example, infrared communication.

Abstract: A wireless communication interface for a portable wireless terminal and a system for wirelessly communicating by a portable wireless terminal with another device via a free space. The interface facilitates aligning the portable wireless device with another devices for improved communication. The interface including: a light source for generating a data-modulated visible light signal and outputting the visible light signal to the free space; an optical detector for generating an electrical signal by photoelectrically converting the visible light signal input from the free space, and for outputting the electrical signal. A demodulation unit demodulates the electrical signal input from the optical detector, and outputs a data signal.

Abstract: A method of providing a visible light communication in a data link layer of a visible light communication system adopting an infrared communication link connection protocol includes: broadcasting a discovery exchange station identification (D-XID) frame; generating a visible frame to provide a visibility to a link for a specified waiting time period for responding to the broadcast D-XID frame; exchanging a set normal response mode (SNRM) frame and an unnumbered acknowledgement (UA) frame for requesting a link setting between the transmitting and receiving terminals; generating visible frames for a waiting time for receiving the SNRM frame and the UA frame; exchanging an information transfer frame (I-frame) and a receive ready (RR) frame, which is a response to the I-frame, between the transmitting and receiving terminals; and generating visible frames for a specified waiting period for receiving the I-frame and the RR frame.

Abstract: A reconnection method and device for a peripheral interface using VLC provide a protocol for when a communication link between a primary device and a secondary device is disconnected. The primary device generates an R-XID message including reconnection information and a warning indication signal indicating the disconnection. The secondary device aligns the communication link with the primary device using the warning indication signal, receives the R-XID message from the primary device by the secondary device, and transmits an R-XID response message for the R-XID message to the primary device.

Abstract: An apparatus and method for controlling the emitted color of visible light according to the current communication state in a visible light communication (VLC) device. The method includes storing one or more communication states and emitting colors that are correspondingly matched to the one or more communication states to indicate each of the various communication states. The VLC also checks, which can be based upon selection of a VLC mode, the current communication state and an emits a color that corresponds to the current communication state and emits the checked color of light to provide a visible light signal that indicates communication status to a user.