KR20090092038A - Method and apparatus for transmitting data in wireless local area network using visible light communication - Google Patents

Abstract

The present invention relates to a data transmission method in a wireless LAN system using visible light communication, wherein a data packet and control information of a data packet are transmitted from a media access control (MAC) layer of a transmitting side to a PHY (physical) layer of a transmitting side during data transmission. Transmitting, transmitting 8B10B encoded data at the PHY layer of the transmitting side to the receiving side together with control information, receiving the data at the PHY layer of the receiving side, decoding the 8B10B, and confirming an error occurrence of the data; In the process of transmitting a feedback message including error occurrence information to the sender at the receiving PHY layer, and receiving the feedback message at the sending MAC layer and inspecting the feedback message, the received 8B10B block is received. Retransmission.

Description

TECHNICAL AND APPARATUS FOR TRANSMITTING DATA IN WIRELESS LOCAL AREA NETWORK USING VISIBLE LIGHT COMMUNICATION}

The present invention relates to a visible light communication system, and more particularly, to a data transmission method and apparatus in a wireless local area network (LAN) system using visible light communication.

As the luminous efficiency of LED (Light Emitting Diode) is improved and the price is lowered, LED is becoming common in general lighting market such as fluorescent incandescent lamp as well as special lighting market such as mobile device, display, automobile, traffic light, billboard. In particular, the luminous efficiency of white LEDs has already surpassed incandescent lamps, and products superior to fluorescent lamps have emerged. Recently, due to the depletion of RF (Radio Frequency) band frequency, the possibility of crosstalk between various wireless communication technologies, the increased demand for security of communication, and the arrival of ultra-fast ubiquitous communication environment of 4G wireless technology, visible light wireless communication technology complementary to RF technology Increasingly, research on visible light wireless communication using visible light LED is being conducted by various companies and research institutes.

Home, office, and public places that currently use fluorescent or incandescent lamps will be replaced by LEDs with good performance and long life. By modulating the current applied to the LED used as a lighting lamp, the lighting LED can be used as a communication light source. In other words, broadcasting and data transmission are possible with only the illumination LED without additional light source. A user who uses a terminal or a laptop in an LED lighting area can perform wireless LAN data communication using a visible light wireless transceiver module.

The biggest difference between the wireless visible light communication and other wireless RF communication is that the user can check the data transmission and reception process, and the straightness of the signal is strong and the data transmission and reception distance is short due to the characteristics of the visible light, which is a transmission medium. Due to the linearity of the signal, when a signal is blocked between an access point (AP) and a mobile node (MN), a data transmission and reception failure occurs.

On the other hand, since the visible light communication transmits and receives a signal through a light source that can be understood by the user, the intensity of the light source must be stable so as not to be tired of the user's eyes. In addition, in consideration of the performance of a light receiving element receiving a signal, for example, a photo diode, a change of a proper amount of 0 and 1 signals is required so as not to miss a sink. Accordingly, in a visible LAN communication system, the 8B10B coding scheme may use a constant ratio of 0 and 1 when transmitting data. When using the 8B10B coding scheme, it is possible to recognize a data block in which a reception error occurs in units of 10 bits for data received from the PHY terminal. Therefore, when a request for retransmission for the failed data is requested, a method of reducing the retransmission overhead by requesting the transmission of the failed data block in 10-bit units is required.

An object of the present invention is to provide a data transmission method and apparatus that can reduce retransmission overhead when retransmitting failed data in a visible light wireless LAN system using 8B10B encoding.

According to one embodiment of the present invention for achieving this, in a data transmission method in a wireless LAN system using visible light communication, a data packet and a control information of the data packet in a MAC (Media Access Control) layer on the transmitting side during data transmission. Is transmitted to the PHY (Physical) layer of the transmitting side, the BHYB encoding of the data in the PHY layer of the transmitting side and transmitted to the receiving side with the control information, and receiving the data at the PHY layer of the receiving side 8B10B decoding and confirming an error occurrence of data; transmitting a feedback message including error occurrence information in the PHY layer of the receiving side to the transmitting side; receiving the feedback message in the MAC layer of the transmitting side; If there is an 8B10B block that failed to receive after checking the feedback message, the 8B10B block that failed to receive It characterized in that it comprises the step of retransmitting.

According to another aspect of the present invention, in a wireless LAN system using visible light communication, the data transmission device transmits a data packet from a MAC layer and control information of the data packet to a PHY layer when transmitting data to a receiver. A sender for 8B10B encoding and transmitting the 8B10B block with the control information to the receiving side, and if there is an 8B10B block that has failed to be received by checking a feedback message in the MAC layer when receiving feedback information; And receiving the data from the PHY layer to decode the 8B10B, confirming that an error occurred in the data, and transmitting the feedback message including the error occurrence information to the transmitting side. It is done.

The present invention has the effect of reducing the retransmission overhead when the retransmission of the failed data transmission and reception in the visible light wireless LAN system using the 8B10B encoding scheme can increase the transmission efficiency.

1 is a diagram illustrating an example of a wireless LAN system using visible light communication to which the present invention is applied.

FIG. 2 is an exemplary diagram illustrating a method of allocating a block number of a packet during data transmission in a visible light wireless LAN system according to an exemplary embodiment of the present invention.

3 is a configuration diagram of a feedback message for retransmission of data in a visible light wireless LAN system according to an exemplary embodiment of the present invention.

4 is a flowchart illustrating a data transmission procedure in a visible light wireless LAN system according to an embodiment of the present invention.

Hereinafter, an apparatus and an operation method of constructing 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 it is understood that these 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.

1 is an exemplary configuration diagram of a wireless LAN system using visible light communication to which the present invention is applied. Referring to FIG. 1, a wireless LAN system using visible light communication includes an access point (AP) 110 and mobile nodes (MNs) 120 and 130. The access point 310 may have its own communicable area 140 for each access point 110 and communicate with mobile nodes 120 and 130 located in the communicable area 140. The mobile nodes 120 and 130 have mobility and are located in the communicable area 140 of the access point 110 where the mobile nodes 120 and 130 are located, and use the visible light as a communication medium to access the corresponding access point 110. Performs wireless communication with The wireless LAN system using visible light communication to which the present invention is applied may use visible light as a communication medium, so that a user may check a data transmission / reception process, visually confirm communication security, and implement low power. Therefore, the position of the transmitting and receiving end can be easily seen by the user, and has a feature of visually confirming the path of communication.

The present invention proposes a method of constructing a feedback message for data retransmission and a data retransmission method using feedback in case of a transmission / reception failure between an access point and a mobile node in the visible light wireless LAN system. First, a method of constructing a feedback message according to an embodiment of the present invention will be described.

In the present invention, feedback information (ACK / NACK) for the received data is not transmitted to the MAC (Media Access Control) layer of the receiver for fast data retransmission. In the present invention, feedback information on the received data is generated at the PHY (Physical) level according to the characteristics of the present invention and fed back to the transmitter. In the present invention, since the data retransmission procedure is not transmitted to the MAC layer of the receiving side, fixed resource allocation for transmitting feedback information is required. The allocation of resources is automatically assigned by the access point when the mobile node or access point creates a data send / receive session. Once allocated, the resources remain in effect until the data session ends, and the size is retransmitted by the access point or mobile node. It is defined as a size enough to transmit information about the data.

The resource for feedback can be allocated to both uplink and downlink. When the feedback resource is allocated to the uplink, the mobile node is used to transmit information about data to be retransmitted to the access point, and the feedback resource is allocated to the downlink. If so, the access point is used to send information about the data to be resent to the mobile node. The feedback resource may be allocated every frame and may be allocated at regular intervals.

The feedback information generated by the mobile node or the access point with respect to the data currently received includes a sequence number (SN), a start block number, and an ACK bitmap.

The sequence number is composed of 1 bit, and is changed from '0' to '1' or '1' to '0' every time data is newly transferred to the PHY layer for data transmission according to scheduling in the MAC layer.

In the visible light wireless LAN system according to an embodiment of the present invention, a data transmission method uses a 'stop and wait' method and transmits data after the PHY terminal successfully transmits data received from the MAC layer to the receiving side. This is done. Accordingly, it is possible to recognize which packet the feedback currently transmitted through the transmission of the sequence number is. The block number is allocated by incrementing by 1 by cutting 10 bits of 8B10B coded data which is initialized to 0 each time the PHY stage receives new data from the MAC layer. After 8B10B encoding, 8-bit data is increased to 10 bits, so the MAC layer allocates data in increments of 1 by 8 bits.

2 is an exemplary view illustrating a block number allocation method of a packet during data transmission in a visible light wireless LAN system according to an embodiment of the present invention. After 8B10B encoding of a MAC packet, a block number is allocated in units of 10 bits. The start block number indicates the block number of the first block of the 8B10B block indicated in the ACK bitmap. Accordingly, the receiving side may determine the sequence number and the start block number to recognize which data block the currently received ACK bitmap is. The ACK bitmap represents information of each block in which one bit is coded 8B10B. If a block fails to receive through the ACK bitmap, it can be recognized by the sender, and only the block is retransmitted by the sender.

3 is a configuration diagram of a feedback message for data retransmission in a visible light wireless LAN system according to an embodiment of the present invention. Referring to FIG. 3, in the visible wireless LAN system according to an embodiment of the present invention, at least one feedback message for retransmitting data is inserted into at least one front part of the feedback to inform the start point of the feedback. More than one will be inserted. The 8B10B control code is followed by a 1-bit sequence number and the start block number. The receiver may recognize which data block the ACK bitmap currently received is based on the sequence number and the start block number. An ACK bitmap is inserted after the start block number, and indicates whether the reception success is received with 1 or 0 for each of the 8B10B coded blocks received by the receiver. In FIG. 3 (a), one bit of each ACK bitmap represents information of one block coded with 8B10B. In this case, the retransmission overhead is minimized by minimizing the retransmission overhead by receiving the failed transmission block in the smallest block unit. However, if the size of the received data is large, the ACK bitmap becomes too large. Therefore, a plurality of 8B10B coded blocks are bundled together so that if one of the blocks fails, all of the corresponding block bundles are retransmitted. FIG. 3B shows a case where an ACK bitmap is created for two blocks coded with 8B10B. Definition of the 8B10B coding block represented by one bit of the ACK bitmap is made through signaling at the time of data session creation.

The method of retransmission of data made through the feedback message configured through the above method will be described. First, the MAC of the transmitting side concatenates several MAC packets to be carried in one slot, and encodes them into 8B10B in the PHY. At this time, the transmitting side transmits the sequence number information and the start block number to the receiving side as control information on the 8B10B encoded packet through the control information transmission channel. The receiving side transmits the sequence number, the start block number, and the ACK bitmap information as the feedback information on the received data to the transmitting side through the assigned feedback slot. The MAC layer of the transmitting side interprets this feedback message and selectively retransmits the 8B10B block that the receiving side has failed to receive. If the retransmission completes successfully, the sequence number is switched, the start block number is reset to zero, and a new packet is transmitted.

A data retransmission operation according to an embodiment of the present invention will be described in more detail with reference to FIG. 4. 4 is a flowchart illustrating a data transmission procedure in a visible light wireless LAN system according to an embodiment of the present invention.

Referring to FIG. 4, first, in step 410, new data for 8B10B encoding is transmitted from the transmitting MAC layer to the transmitting PHY layer. At this time, the MAC layer sets the sequence number to '0', initializes the block number to '0', sets the start block number to '0', and transmits the corresponding information along with the data to the PHY layer. After receiving this, the PHY layer of the transmitting side transmits the packet (first packet) encoded in step 420 to the PHY layer of the receiving side after 8B10B encoding.

Next, the receiving PHY detects an 8B10B block in which an error occurs through 8B10B decoding, and transmits the information about this to the transmitter through a fixedly allocated feedback resource in step 430. If an error occurs in the fourth and fifth 8B10B encoding blocks of the received data, this information is displayed in the ACK bitmap and a feedback message is transmitted to the sender. In step 430, the MAC layer of the transmitting side receives the feedback message transmitted in step 440, and transmits the corresponding block in which the error occurs to the PHY layer of the transmitting side. In step 450, 8B10B encoding is performed in the PHY layer of the transmitting side. The error occurred in the encoded packet (first packet) transmitted in the step is retransmitted to the PHY layer of the receiving side.

Next, 8B10B decoding is performed in the PHY layer of the receiving side. In step 460, a feedback message is transmitted from the PHY layer of the receiving side to the transmitting side. As the transmission is successfully performed at the receiving side, the sequence number is toggled at the transmitting MAC layer, the new data is transmitted to the transmitting PHY layer at step 470, and 8B10B encoding is performed at the transmitting PHY layer. In operation 480, the encoded packet (second packet) is transmitted to the PHY of the receiver.

As described above, the operation and configuration of a data transmission method and apparatus in a wireless LAN system using visible light communication according to an embodiment of the present invention can be made. Meanwhile, in the above description of the present invention, specific embodiments have been described. Modifications may be made without departing from the scope of the present invention.

Claims (20)

A data transmission method in a wireless LAN system using visible light communication, Transmitting a data packet and control information of the data packet to a PHY (physical) layer of a transmitting side at a transmitting side of a MAC (Media Access Control) layer during data transmission; 8B10B encoding the data in the PHY layer of the transmitting side and transmitting the data together with the control information to the receiving side; Receiving the data from the PHY layer of a receiving side and decoding the 8B10B and confirming an error of the data; Transmitting a feedback message including error occurrence information to the transmitting side in the PHY layer of the receiving side; In a wireless LAN system using visible light communication, if the 8B10B block fails to receive the feedback message after receiving the feedback message at the transmitting MAC layer and inspecting the feedback message, retransmitting the failed 8B10B block. Data transfer method. The method of claim 1, wherein the control information of the packet, A sequence number consisting of 1 bit and 0 and 1 are switched each time new data is transmitted from the transmitting MAC layer to the transmitting PHY layer for data transmission; An 8B10B block is initialized each time data is received from the MAC layer of the transmitting side in the PHY layer of the transmitting side and assigned to an 8-bit block before the 8B10B encoding or a 10-bit block after the 8B10B encoding. When the block number of the (Block number), the data transmission method in a wireless LAN system using visible light communication comprising a start block number (Start Block Number) which is the block number of the first block transmitted to the receiving side. The 8B10B block according to claim 2, wherein if there is an 8B10B block that has received the feedback message at the sending MAC layer and inspected the feedback message, the reception failed. The sequence number is not changed, and the start block number is set to the block number of the first 8B10B block transmitted to the receiving side. The 8B10B block according to claim 2, wherein if there is no 8B10B block that has received the feedback message at the sending MAC layer and inspected the feedback message, the reception failed. Transmit the sequence number, initialize the start block number to 0, transmit new data packets to the PHY layer on the transmitting side, encode 8B10B, and transmit them to the receiving side. Way. The method of claim 2, wherein the control information of the packet is transmitted through a predetermined control information transmission channel. The method of claim 2, wherein the receiving side allocates a fixed resource for transmitting the feedback message. 7. The method of claim 6, wherein the resource allocation is automatically allocated when creating a data transmission / reception session, and once allocated resources are valid until the data session is terminated, and the size of the allocated resources indicates information about data to be retransmitted. A data transmission method in a wireless LAN system using visible light communication, characterized in that the size set enough to transmit enough. 10. The method of claim 7, wherein the resource can be allocated to both uplink and downlink, and the resource for the feedback message can be allocated every frame and can be allocated at regular intervals. Data transmission method in LAN system. The method of claim 2, wherein the feedback message is One or more 8B10B control codes inserted at the beginning of the feedback to indicate when to start the feedback, The sequence number received; The start block number received; And a ACK bitmap indicating whether or not each receiving block coded by 8B10B has been successfully received by the receiving side. The method of claim 9, wherein each bit constituting the ACK bitmap, Indicates whether the reception of each block coded with 8B10B is successful, or A data transmission method in a wireless LAN system using visible light communication, characterized in that indicates the reception success information of a plurality of predetermined blocks coded by 8B10B. A data transmission apparatus in a wireless LAN system using visible light communication, When transmitting data to the receiving side, the MAC (Media Access Control) layer transmits the data packet and the control information of the data packet to the PHY (Physical) layer to encode the data packet and transmits the 8B10B to the receiving side along with the control information. A sender for retransmitting the failed 8B10B block when there is an 8B10B block that has failed to be received by checking a feedback message in the MAC layer when receiving information; And receiving the data from the PHY layer to decode the 8B10B, confirming that an error occurred in the data, and transmitting the feedback message including the error occurrence information to the transmitting side. Data transmission device in a wireless LAN system using visible light communication. The method of claim 11, wherein the control information of the packet, A sequence number consisting of 1 bit and having 0 and 1 switched each time new data is transferred from the transmitting MAC layer to the transmitting PHY layer according to scheduling; An 8B10B block is initialized each time data is received from the MAC layer of the transmitting side in the PHY layer of the transmitting side and assigned to an 8-bit block before the 8B10B encoding or a 10-bit block after the 8B10B encoding. In the case of a block number, the data transmission device in a wireless LAN system using visible light communication, comprising: a start block number which is a block number of a first block transmitted to a receiving side. The method of claim 12, wherein when there is an 8B10B block in which the reception side fails to receive the feedback message, The sequence number is not changed, and the start block number is set to the block number of the first 8B10B block transmitted to the receiving side, the data transmission apparatus in a wireless LAN system using visible light communication. The method according to claim 12, wherein when there is no 8B10B block that has failed to receive by checking the feedback message of the transmitting side, Transmit the sequence number, initialize the start block number to 0, transmit new data packets to the PHY layer on the transmitting side, encode 8B10B, and transmit them to the receiving side. Device. The apparatus of claim 12, wherein the control information of the packet is transmitted through a predetermined control information transmission channel. The apparatus of claim 12, wherein the receiving side allocates resources to transmit the feedback message in a fixed manner. 17. The method of claim 16, wherein the resource allocation is automatically allocated when creating a data transmission / reception session, the once allocated resource is valid until the data session is terminated, and the size of the allocated resource indicates information about data to be resent. A data transmission device in a wireless LAN system using visible light communication, characterized in that the size set enough to transmit enough. 18. The method of claim 17, wherein the resource may be allocated to both uplink and downlink, and the resource for the feedback message may be allocated every frame, and may be allocated at regular intervals. Data transfer device in LAN system. The method of claim 12, wherein the feedback message is One or more 8B10B control codes inserted at the beginning of the feedback to indicate when to start the feedback, The sequence number received; The start block number received; And an ACK bitmap indicating whether or not each of the blocks coded by 8B10B received by the receiving end is successful. The method of claim 19, wherein each bit constituting the ACK bitmap, Indicates whether the reception of each block coded with 8B10B is successful, or A data transmission apparatus in a wireless LAN system using visible light communication, characterized in that indicating the success or failure information of a plurality of predetermined blocks coded by 8B10B.