KR20080108732A - Method and apparatus for transmitting/receiving data in a visible light communication system - Google Patents

Abstract

A data transmitting/receiving method in a visible light communications system and an apparatus thereof are provided to perform communication in a communications channel by using the visible light through the operation procedure of the data transmitting/receiving method in a visible light communications system. A preamble(510) includes signal in which 1 and 0 are repeated as predetermined bit number. An STA includes the specific bit string and informs the beginning of the frame. An infoblock(530) expresses the information of a visible pattern block. A visible pattern block(540) defines as a code which does not use in a 8B10B coded system. An STO(550) includes the specific bit string and informs the end of frame.

Description

METHOD AND APPARATUS FOR TRANSMITTING / RECEIVING DATA IN A VISIBLE LIGHT COMMUNICATION SYSTEM}

1 is a block diagram illustrating an example of data transmission in a general Ethernet (Ethernet) system

2 is a flowchart illustrating an example data transmission / reception process of a general Ethernet system

3 is a block diagram illustrating an apparatus for transmitting and receiving visible light according to an embodiment of the present invention.

4 is a block diagram illustrating an example of data transmission in a visible light communication system according to an exemplary embodiment of the present invention.

5 is a flowchart illustrating a data transmission process in a visible light communication system according to an exemplary embodiment of the present invention.

6 is a configuration diagram of a visible frame of a visible light communication system according to an exemplary embodiment of the present invention.

7 is a view illustrating a period of a visible frame in a visible light communication system according to an exemplary embodiment of the present invention.

The present invention relates to a visible light communication system, and more particularly, to a method for transmitting and receiving data in a visible light communication system.

In the Open Systems Interconnection (OSI) model, the Data Link layer is responsible for the communication link and performs the related functions. Therefore, the frame used for communication is defined and various things are defined to transmit it effectively. Typical functions include address structure of frames, basic flow control, error control, and access to communication media.

1 is a diagram illustrating an exemplary frame configuration for data transmission in a general Ethernet system. Referring to FIG. 1, a frame structure for data transmission in a general Ethernet system includes an analog preamble for transmitting synchronization information between a transmitter and a receiver, and a payload of data including information actually transmitted. Data frame which is payload, Digital preamble indicating the start of the data frame, Control frame for communication link control, Acknowledgment frame indicating response of data transmission of the other party It is configured to include. With reference to the description of Figure 1 will be described the transmission and reception of each frame when transmitting and receiving data in a general Ethernet system.

2 is a flowchart illustrating an example data transmission / reception process of a general Ethernet system.

2 (a) shows a flow of data between a transmitting side and a receiving side in a data transmission / reception process of a general Ethernet system. As shown in FIG. 2A, a sender transmits a control frame to a receiver. Then, after receiving the control frame, the receiving side transmits an ACK frame to the transmitting side in order to respond to the received control frame to establish a link between the transmitting side and the receiving side. The transmitting side transmits the data frame to the receiving side to start the actual data communication using the established link, and the receiving side transmits the ACK frame to the transmitting side to perform the data communication in response to the received data frame. The data frame transmitted after the control frame, the ACK frame, and the transmitted link and the ACK frame, which is a response frame, are transmitted together with the digital preamble at the time of transmission and are transmitted after the digital preamble.

2 (b) shows the flow of frames transmitted and received during data transmission in a general Ethernet system. When trying to communicate between the transmitter and the receiver, the data link is configured as follows. As described in FIG. 2 (a), when the digital preamble and the control frame are transmitted from the transmitting side to the receiving side for link establishment, the receiving side receives the control frame and then transmits the digital preamble and ACK frame to the transmitting side so that the link is established. Notify The transmitting side transmits the digital preamble and the data frame through the established link, and the receiving side transmits the digital preamble and the ACK frame to the transmitting side in order to respond to the received data to perform link setting and data transmission.

FIG. 2C shows the data flow of the portion 210 indicated by a dotted line during the transmission process of FIG. 2B described above. As shown in (c) of FIG. 2, in the data transmission process of a general Ethernet system, the transmitting side and the receiving side are not only not only transmitting data from the transmitting side to the receiving side or receiving side but also not transmitting data. It transmits an analog preamble to each counterpart and operates to maintain synchronization between transceivers.

When the type of communication protocol described above is applied to a communication system using visible light, the visible light transmitter (TX) and the receiver (RX: receiver) keep the output of the visible light signal 'ON' due to the analog preamble. shall. Since the transmitter and receiver output signals are always 'ON', there is no change in the visibility of the communication and there is no visible difference in the information. In addition, since it is a suitable protocol on a wire without considering power, there is a problem that unnecessary power is consumed by always keeping the transceiver output state 'ON'.

Accordingly, in the visible light communication system, a communication protocol suitable for a visible light communication system capable of performing a function provided by the existing data link layer and providing visibility to a communication channel is required.

An object of the present invention is to provide a data transmission / reception method and apparatus capable of performing a function provided by an existing data link layer and providing visibility to a communication channel in a visible light communication system.

According to one embodiment of the present invention for achieving this, in a method for transmitting and receiving data in a visible light communication system, a step of transmitting a control frame for link control from a transmitting side to a receiving side, and the receiving side controlling the control. Receiving an frame and transmitting an acknowledgment (ACK) frame to the transmitting side for a response, transmitting the data frame containing information from the transmitting side to the receiving side, receiving and responding to the data frame at the receiving side Transmitting an ACK frame to the transmitting side for transmitting the ACK frame, and when the transmitting side and the receiving side do not transmit each frame for communication, a visible frame is provided to provide a visibility to the communication link. Characterized in that the transmission to the side.

According to another aspect of the present invention, in a data transmission / reception apparatus in a visible light communication system, a control frame for link control is transmitted to a receiving side, an acknowledgment frame for the control frame is received, and information is received. A transmitting side that transmits a data frame containing the data frame to the receiving side, and receives the control frame from the transmitting side, and transmits an acknowledgment frame to the transmitting side for a response to the control frame, A receiving side receiving the data frame from the side and transmitting an ACK frame to the transmitting side in response to the data frame, and not transmitting each frame for communication at the transmitting side and the receiving side. Visible Frames to provide visibility into the communications link during off hours. ) Is transmitted to the other side.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific components are shown, which are provided to help a more general understanding of the present invention, and the specific details may be changed or changed within the scope of the present invention. It is self-evident to those of ordinary knowledge in Esau. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

3 is a block diagram of an apparatus for transmitting and receiving visible light according to an embodiment of the present invention. As shown in FIG. 3, the visible light communication apparatus 200 according to an exemplary embodiment may include a controller 210, a visible light communication transmitter 212, a visible light communication receiver 214, a pulse generator 222, and a pulse. It includes a recovery unit 224, a modulator 232, a demodulator 234.

The controller 210 performs an overall control operation of the visible light communication transceiver 200. In particular, in the present invention, the control unit 210 controls to output a visible frame described below at a predetermined interval when performing visible light communication. In addition, the data received through the visible light communication is stored in the memory unit 240.

First, an operation of transmitting data in the visible light communication device will be described with reference to the configuration of FIG. 3.

First, under the control of the controller 210, the pulse generator 222 generates a pulse signal corresponding to data for transmission and outputs the pulse signal to the modulator 232. Then, the modulator 232 modulates the input pulse signal into a signal suitable for visible light communication and outputs it to the visible light communication transmitter 212.

In this case, the visible light communication transmitter 212 outputs the visible light signal according to the control signal of the controller 210. The visible light communication transmitter 212 may be configured using a laser diode (LD), a light emitting diode (LED), or an array thereof.

Next, an operation of receiving data in the visible light communication device 200 will be described with reference to the configuration of FIG. 3.

When a visible light signal transmitted from another visible light communication device is input to the visible light communication receiver 214, the visible light communication receiver 214 converts the input visible light signal into an electrical signal and outputs the electrical signal. In this case, the visible light communication receiver 214 may be configured as a photo diode converting an electric signal when light is input to the outside.

Meanwhile, the demodulator 234 demodulates the received electric signal into data according to the visible light communication method and outputs the demodulated signal to the pulse recovery unit 224. Then, the pulse recovery unit 224 recovers the input electrical signal into a pulse signal and outputs it to the control unit 210.

Next, a transmission / reception operation in the visible light communication system using the visible light communication transceiver configured as shown in FIG. 3 will be described.

4 is a diagram illustrating an example frame configuration when transmitting data in a visible light communication system according to an exemplary embodiment. As shown in FIG. 4, a frame of a visible light communication system according to an embodiment of the present invention includes a data frame, which is a payload of data including information to be actually transmitted, and a CDR (Clock-Data) of a receiver. Digital preamble which performs a function of providing a signal for recovery and announcing the start of a data frame, an acknowledgment frame indicating a response to data transmission of the other party, and a control for controlling a communication link ( Control frame and a Visible frame for providing visibility of the communication link in the visible light communication operation.

The data transmission / reception method in the visible light communication system according to an embodiment of the present invention may implement a data link having visibility without continuously transmitting a signal at the time of transmission and reception using the above-described visible frame. Referring to Figure 5 will be described in more detail the data transmission and reception method in the visible light communication system according to an embodiment of the present invention.

5 is a flowchart illustrating a data transmission process in a visible light communication system according to an exemplary embodiment.

FIG. 5 (a) shows the flow of data between a transmitting side and a receiving side in a data transmission and reception process of a visible light communication system according to an exemplary embodiment of the present invention. As shown in FIG. 5A, a sender first transmits a control frame to a receiver for communication link control. Then, after receiving the control frame, the receiving side transmits an ACK frame to the transmitting side in response to the received control frame to establish a link between the transmitting side and the receiving side. The transmitting side transmits a data frame containing information to the receiving side to start actual data communication using the established link, and the receiving side transmits an ACK frame to the transmitting side to perform data communication in response to the received data frame. The data frame transmitted after the control frame, the ACK frame, and the transmitted link and the ACK frame, which is a response frame, are transmitted together with the digital preamble at the time of transmission and are transmitted after the digital preamble.

5B illustrates a frame transmitted and received during a data transmission process of a visible light communication system according to an exemplary embodiment of the present invention. The transmission and reception operation of the visible light communication system according to an embodiment of the present invention is characterized by using a visible frame to provide visibility to a communication link according to an aspect of the present invention. In detail, the transmitting side and the receiving side continuously transmit visible frames at predetermined intervals to provide visibility.

Referring to FIG. 5B, while transmitting the visible frame, the transmitting side stops transmitting the visible frame and transmits the digital preamble and the control frame to establish a link. When the transmission of the digital preamble and the control frame is completed, the visible frame is continuously transmitted to the receiver to ensure visibility. The receiving side periodically transmits the visible frame to the transmitting side before receiving the control frame from the transmitting side, and when receiving the control frame from the transmitting side, stops the transmission of the visible frame and sends the digital preamble and ACK to respond to the control frame. The frame is transmitted to the transmitting side, and after transmitting the ACK frame, the visible frame is continuously transmitted to ensure visibility. When the transmitting side transmits the visible frame and receives the ACK frame from the receiving side, the transmitting side stops transmitting the visible frame and transmits the digital preamble and the data frame to the receiving side for actual data transmission. When transmission of the data frame is completed, the visible frame is transmitted to the receiving side again to secure visibility. When the receiving side transmits the visible frame and receives the data frame, the receiving side stops transmitting the visible frame and transmits an ACK frame for the response. After transmitting the ACK frame, the visible frame is transmitted again to ensure visibility.

FIG. 5C is a flowchart illustrating in detail the data flow of the portion 410 indicated by the dotted line in the data transmission process of FIG. 5A, and FIG. 5D is the FIG. A flow chart showing in more detail the data flow of the portion 420 indicated by a dotted line in the data transmission process of (a).

The operation of the transmitter will be described first with reference to FIGS. 5C and 5D. Referring to FIG. 5C, when the transmitting side transmits a control frame to the receiving side and the control frame is transmitted, the transmitting side transmits a visible frame to the receiving side for visibility of the communication link. When the transmitting side receives an ACK frame that is a response to the control frame from the receiving side while transmitting the visible frame, the transmitting side stops transmitting the visible frame and transmits the data frame.

Subsequently, referring to FIG. 5D, the transmitting end transmits the data frame to the receiving side, and when the transmission of the data frame is completed, transmits the visible frame to the receiving side again. When receiving an ACK frame that is a response to a data frame from the receiving side while transmitting the visible frame, the transmitting side stops transmitting the visible frame and transmits the next data frame.

Next, referring to FIGS. 5C and 5D, the receiving side transmits the visible frame to the transmitting side and stops transmitting the visible frame when receiving the control frame from the transmitting side. An ACK frame, which is a response to one control frame, is transmitted to the transmitter. After transmission of the ACK frame, the visible frame is output again to the transmitting side.

Referring to FIG. 5 (d), when a receiving side transmits a visible frame to a transmitting side and receives a data frame, the receiving side stops transmitting the visible frame and transmits an ACK frame, which is a response to the received data frame, to the transmitting side. After transmission of the ACK frame, the visible frame is transmitted to the transmitter again.

In the description of FIGS. 5C and 5D, the digital preamble is omitted.

Referring to FIGS. 5C and 5D, in a data transmission / reception process of a visible light communication system according to an exemplary embodiment of the present invention, data is transmitted as well as when data is being transmitted from a transmitting side to a receiving side or a receiving side from a transmitting side. Even when not transmitting, the transmitting side and the receiving side continue to transmit the visible frame at a predetermined interval to the other side to provide visibility of the communication channel.

6 is a configuration diagram of a visible frame of a visible light communication system according to an exemplary embodiment of the present invention. As shown in FIG. 6, a visible frame of a visible light communication system according to an embodiment of the present invention includes a preamble 510, a STA 520, an Info block 530, an STO 550, It is configured to include a visible pattern block (540). According to an embodiment of the present invention, the visible frame may be configured in two different ways as shown in FIG. 6 according to an implementation method, and the transceiver structure may also be changed according to the above implementation method.

The preamble 510 is a signal in which '1' and '0' of '1010101010' are repeated so that the CDR (Clock Data Recovery) of the receiving end recovers the clock and the data. It is set to a bit length as long as enough time, and is preferably set to 10 bits (Bit). The CDR performs a function of extracting (recovering) a clock signal and a data signal from the received signal based on the received packet.

The STA 520 performs a function of notifying the start of a frame (Begin Flag) and is indicated by a specific bit string, and is the same as Ultra fast IrDa (UFIR) in the VLC protocol according to an embodiment of the present invention. Set it to

The STO 550 performs an end flag function for notifying the end of a frame and is displayed in a specific bit string.

The info block 530 is a flag indicating information of the visible pattern block 540. The info block 530 has a packet type portion for marking a visible frame with a size of 1 byte, a payload pattern portion for defining a payload pattern with a size of 1 byte, and a size of 2 bytes. It includes a length portion that defines the length of the visible pattern. The length portion sets the maximum length of the visible frame to 32 KBytes.

The visible pattern block 540 is defined as a code not used for the 8B10B coding scheme. The code is as follows.

-11111 11111-11110 11111

-11110 11110-11101 11100

-11001 11100-10001 11100

-00001 11100-00001 11000

-00001 10000-00001 00000

-00000 00000

7 is a diagram illustrating a period of a visible frame in a visible light communication system according to an exemplary embodiment. The method of determining the period of the visible frame may be determined using Equation 1 below by measuring the light brightness of the visible light communication module.

Visible Frame Gap Time  = Visible Frame Length  * Visible Throshold

The Visible Frame Gap Time is an interval between the visible frames, the Visible Frame Length is a length of the visible frame, and Visible Threshold is a visible threshold.

As shown in FIG. 7, when the visible light link is configured with the visible light transmitter having the visible threshold value of 0.3, the gap between the visible frames is controlled within 30% of the visible frame length, and the visible frames are transmitted at the above intervals. Thus, a data link layer having visibility can be formed.

As described above, the operation and configuration of a data transmission / reception method and apparatus in a visible light communication system according to an embodiment of the present invention can be made. Meanwhile, the above-described description of the present invention has been described with reference to specific embodiments. It may be practiced without departing from the scope of the invention.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention not only can perform a unique function of communication in a communication channel using visible light through an operation procedure of a data transmission / reception method in such a visible light communication system, but operates a transceiver only when communication is desired while providing visibility to the communication link. There is an effect that can implement a visible light communication channel with low power consumption.

Claims (10)

A method of transmitting and receiving data in a visible light communication system, Transmitting a control frame for link control from a transmitter to a receiver; Receiving the control frame at the receiving side and transmitting an acknowledgment (ACK) frame to the transmitting side for a response; Transmitting a data frame containing information from the transmitting side to the receiving side; Receiving the data frame at the receiving side and transmitting an ACK frame to the transmitting side for a response; When the transmitting side and the receiving side does not transmit each frame for communication, a visible frame (Visible Frame) is transmitted to the other side in order to provide visibility to the communication link, the data transmission and reception method in the visible light communication system . The method of claim 1, wherein the visible frame is repeatedly transmitted at a predetermined interval. The method of claim 2, wherein the interval between the visible frames, Method of transmitting and receiving data in a visible light communication system, characterized in that using the following equation (2). Visible Frame Gap Time  = Visible Frame Length  * Visible Throshold The Visible Frame Gap Time is an interval between the visible frames, the Visible Frame Length is a length of the visible frame, and Visible Threshold is a threshold. The method of claim 1, wherein the control frame, the data frame, and the ACK frame are transmitted together with a digital preamble and transmitted after the digital preamble. The method of claim 1, wherein the length of the visible frame is set to a maximum of 32 KBytes. The method of claim 1, wherein the visible frame A preamble consisting of a signal in which '1' and '0' are repeated by a predetermined number of bits; An STA configured with a specific bit string to indicate the start of a frame; An info block representing information of a visible pattern block, A Visible Pattern block defined by a code not used in the 8B10B coding method, And a STO composed of a specific bit string to indicate the end of the frame. 7. The method of claim 6, wherein the length of the preamble is set in consideration of a time when a clock (CDR) on the receiving side recovers a clock and data. 7. The method of claim 6, wherein the length of the preamble is set to 10 bits. The method of claim 6, wherein the info block, A visible light communication system comprising a packet type portion for marking a visible frame, a payload pattern portion for defining a pattern of a payload, and a length portion for indicating the length of the visible frame. Data transmission / reception in A data transmitting and receiving device in a visible light communication system, A transmitting side transmitting a control frame for link control to a receiving side, receiving an acknowledgment frame for the control frame, and transmitting a data frame containing information to the receiving side; Receives the control frame from the transmitting side and transmits an ACK (Acknowledge) frame to the transmitting side for a response to the control frame, and receives the data frame from the transmitting side to respond to the data frame Receiving side for transmitting an ACK frame to the transmitting side for, The apparatus for transmitting and receiving data in a visible light communication system, wherein a visible frame is transmitted to a counterpart in order to provide visibility to a communication link at a time when the transmitting side and the receiving side do not transmit each frame for communication. .

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