KR100683417B1 - Apparatus and method of packet relay in wireless network, MAC layer data structure therein - Google Patents

Abstract

Disclosed are a packet relay apparatus, a relay method, and a medium access control layer data structure used in the wireless network, which perform packet relay between terminal equipment (TE) connected to a wireless network. According to the present invention, a packet relaying method in a wireless network includes: (a) reading a destination address included in a received packet and determining whether the address matches its own address; And (b) forwarding the received packet to a next destination address if it matches, and discarding the received packet if it does not match. Accordingly, in constructing a network in multiple stages, by providing a relay function in a terminal device without additionally providing a relay device, packet relaying can be performed without interference between relay devices, and a wireless network can be easily constructed.

Description

Packet relay apparatus, relay method, and medium access control layer data structure used in the wireless network {Apparatus and method of packet relay in wireless network, MAC layer data structure therein}

1 is a reference diagram for explaining packet forwarding in a mesh structure wireless network;

2 is a diagram illustrating a structure of a packet transmitted and received at a physical layer (PHY) of a terminal device (TE) including a packet relay device of the present invention;

3 is a reference diagram for explaining addressing according to a packet relaying method of the present invention in a multi-stage wireless network;

4 is a diagram illustrating a packet structure of a medium access control (MAC) layer and a physical layer of a packet relay apparatus according to the present invention;

5 is a block diagram of a packet relay apparatus included in a terminal apparatus according to the present invention.

The present invention relates to a wireless network, and more particularly, to a packet relay apparatus, a relay method, and a medium used in the wireless network, which perform packet relay between terminal equipments (TEs) connected to the wireless network. An access control layer data structure.

Unlike a star topology network structure in which an access point (AP) is directly connected to all terminal devices (TEs) to transmit and receive packets, a mesh topology and a tree topology are used. Or in a wireless network such as a serial topology, send packets to or receive packets from a terminal device (TE) other than the terminal device (TE) that is directly connected to the access point (AP). To this end, conventionally, a separate relay device is further provided to transmit and receive the packet. In addition, in order to transmit a packet to a desired destination, the access point (AP) includes only the address of the transmitting device and the address of the receiving device, but does not include information about the relay device.

However, in a multilevel wireless network such as a mesh structure, a tree structure, or a serial structure, a plurality of terminal devices (TEs) are connected to one terminal device (TE), and packets must be delivered to the final destination along one of the paths. In this case, the forwarding process of the packet is complicated because all terminal devices TE need to know information about which path the packet from the access point should follow. In addition, since the size of a packet to be transmitted at a time is large, even if an error occurs in only a part of the packet during each terminal device (TE), the entire packet has to be retransmitted, thereby reducing the data transmission efficiency of the network. .

Accordingly, the technical problem to be achieved by the present invention is to provide a relay of a packet in a media access control layer of each terminal device without further providing a separate relay device in a multi-stage wireless network such as a mesh structure, a tree structure, or a serial structure. A relay apparatus for performing packet relay by adding a data retransmission function in charge thereof and a relay method thereof.

Another object of the present invention is to provide a media access control layer data structure used in the relay apparatus and the relay method.

Another object of the present invention is to reduce the packet size by a predetermined frame in order to increase the efficiency of the network when an error occurs in a packet received from each terminal device (TE) in the multi-stage wireless network. It is to provide a way to cut and retransmit.

According to an aspect of the present invention, there is provided a packet relaying method in a wireless network, comprising: (a) reading a destination address included in a received packet and determining whether the address matches its own address; And (b) forwarding the received packet to the next destination address if it matches, and discarding the received packet if it does not match.

The received packet includes a header field for recording a source address, a destination address, and a final destination address; And a data field, and the data field is preferably divided into frames having a predetermined size.

On the other hand, according to another aspect of the present invention, the technical problem is a packet relay device in a wireless network, the determination unit for reading the destination address included in the received packet and determines whether the address matches its own address; And a relay unit for forwarding the received packet to a next destination address if it matches, and discarding the received packet if it does not match.

In addition, according to another field of the present invention, the technical problem is a data data structure transmitted and received in the medium access control layer of a wireless network, the header field recording the source address, destination address and the final destination address; And a data field, wherein the data field is also achieved by a medium access control data data structure, characterized in that it is divided into frames of a predetermined size.

On the other hand, in the packet relaying method, if the packet to be relayed is a control data packet, one frame constituting the control data packet is transmitted first, and the next frame is received when the Ack message is received from the receiving end. If a timeout occurs due to a message that an error has occurred or an acknowledgment message has not been received for a predetermined time, the frame is transmitted again.If the packet to be relayed is a real data packet, only the frame without errors among the frames constituting the data packet is transmitted. An errored frame is also achieved by the packet relay method, which is characterized in that it does not transmit.

In addition, according to another field of the present invention, the technical problem is a camera connected to a wireless network, the network interface including a physical layer processing unit and a media access control layer processing unit; A determination unit which reads the destination address included in the packet received through the network interface unit and determines whether the address matches its own address; And a relay unit which forwards the received packet to a next destination address if it matches, and discards the received packet if it does not match.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a reference diagram for explaining packet forwarding in a mesh structure wireless network.

In a mesh topology wireless network, a plurality of terminal devices (TE) 110-1 to 130-3 are connected to one access point 100. However, since some terminal devices are not directly connected to the access point 100, in order to deliver packets to these terminal devices, terminal devices located therebetween must perform a function of relaying packets. For example, the terminal device 1 (TE1) 110-1 is responsible for its relay function to forward packets from the access point 100 to the terminal device 1 (TE2) 110-2. That is, if the TE1 110-1 receives the packet and is not a packet destined for the TE1 110-1, the TE2 110-2 receives the packet by retransmitting the received packet. Similarly, in order to forward the packet to TE7 130-3, TE5 130-1 and TE6 130-2 perform their relay functions. The terminal device TE may be any device but may be, for example, a camera connected to a wireless network to wirelessly transmit recorded data.

The packet relay process described above will be described in more detail as follows. In order to transmit a packet to a terminal device (TE) belonging to the class b (152), the terminal device (TE) belonging to the class a (150) serves as a relay, and the terminal device belonging to the class c (154) In order to transmit the packet to the (TE), the terminal device (TE) belonging to the class a (150) and the class b (152) both serves as a relay. However, all of the terminal devices (TE) belonging to class a (150) or class b (152) receive packets from the access point 100 and perform retransmission if they are not packets destined for themselves. A conflict occurs. Therefore, the terminal device (TE) that receives the packet does not perform retransmission, but designates a terminal device to retransmit based on address information included in the data of the media access control (MAC) layer. It is necessary.

FIG. 2 is a diagram illustrating a structure of a packet transmitted and received in a physical layer (PHY) of a terminal device TE including a packet relay device of the present invention.

Referring to FIG. 2, a packet transmitted and received at a medium access control layer of a terminal device TE includes a signal 220 and data 230. In the physical layer (PHY), a preamble 210 is added to form a transmit / receive packet. The preamble 210 records synchronization data for determining a start position of a packet received at the receiving terminal device TE. The signal 220 is header data and includes an address (Src ID) of a sending terminal device, an address (Dst ID) of a receiving terminal device, an address (Tgt ID) of a final destination terminal device, and an ID of a local network (Network ID). It includes. The data 230 records the data to be actually transmitted.

In other words, Src ID, Dst ID, and Tgt ID are included in the header of the medium access control layer packet to designate which terminal device (TE) performs the packet relay function. That is, among the plurality of terminal devices TE that have received the packet, the terminal device TE whose header is the same as the Dst ID is read by reading the header. At this time, if the Dst ID and the Tgt ID are different from each other, the packet is delivered to the terminal device having the Tgt ID. If the Dst ID and the Tgt ID are the same, the packet is determined to arrive at the final destination terminal device and the packet relaying is terminated.

3 is a reference diagram for explaining addressing according to the packet relaying method of the present invention in a multi-stage wireless network.

Referring to FIG. 3, an example in which the access point 310 transmits a response message to the TE3 340 and the TE3 340 transmits a response message to the access point 310 will be described. do. At this time, addressing is made in the form of (A, B, C), where A is the address of the sending terminal device, B is the address of the receiving terminal device, and C is the address of the final destination terminal device.

First, when the access point 310 transmits a packet by designating an address such as (AP, TE1, TE3), the TE1 320 and the TE2 330 receive the packet. TE2 330 discards this packet because its ID and destination ID do not match, and TE1 320 receives and resends this packet because its ID and destination ID match. When resending, TE1 320 resends by designating an address such as (TE1, TE3, TE3).

Then, TE3 340 and TE4 350 receives this packet, TE4 350 discards the received packet because it is not its own packet, and TE3 340 receives the packet because it is its own packet. Since it matches the address of the final destination terminal device, it has the authority to send a response message in response. The addressing of the response message is performed by changing only the Src ID and the Dst ID without changing the address of the final destination terminal device as (TE3, TE1, TE3). Among the TE1 320 and the TE4 350 receiving the response message, the TE4 350 discards the received response message because it is not its own packet, and the TE1 320 receives the response message (TE1, AP, TE3). Resend the response message by specifying the address as follows. Then both the AP 310 and the TE2 330 receive a response message, but the AP 310 with the Dst ID finally receives the response message.

4 is a diagram illustrating a packet structure of a media access control (MAC) layer and a physical layer of a packet relay apparatus according to the present invention.

The data stream 410 coming down from the upper layer includes data 411 and a sequence number (SN) 412, followed by a cyclic redundancy check (CRC) 413 followed by the sequence number SN. It is made of a payload data unit (PDU) (420). The MAC header is added in front of the payload data unit (PDU) 420 to be delivered to the physical layer. The physical layer adds physical layer information to the MAC header to create a signal frame 421, adds a CRC 422 to it, and then attaches a preamble 423 to complete the configuration of a wireless transmit / receive packet.

5 is a block diagram of a packet relay apparatus included in a terminal apparatus according to the present invention.

The packet relay apparatus includes a physical layer processor 510, a media access control layer processor 520, and a controller 530, and the controller 530 includes a determiner 532 and a relay 534. The physical layer processor 510 and the media access control layer processor 520 are called network interface units. The packet received by the physical layer processor 510 is transferred to the media access control layer processor 520 according to the determination of the controller 530. The determination unit 532 reads the destination address included in the received packet and determines whether the address matches the address of the terminal device TE including the packet relay device. The relay unit 534 forwards the received packet to the next destination address if the destination address matches and ignores it if it does not match.

In this case, the received packet includes a header field that records the source address, the destination address, and the final destination address, and a data field that records the actual data to be transmitted. The data field is not composed of one frame, but several data fields. It is divided into frames. The size of the frame can be variably determined according to the state of the network without needing to be specified.

In addition, if the received packet is a control data packet, the relay unit 534 transmits one frame constituting the control data packet first, and sends the next frame when receiving an acknowledge message that the received message is received without error, indicating that an error has occurred. If a message or time has elapsed because it did not receive an acknowledgment for a certain time, the frame is retransmitted. If the received packet is an actual data packet instead of control data, only an error-free frame is transmitted among the frames constituting the data packet, and an error frame is not transmitted. Hereinafter, this retransmission process will be described in more detail.

Automatic Repeat Request (ARQ), which retransmits an errored packet, is an error control protocol that requires the receiver to retransmit lost data. The stop-and-wait ARQ, Go-back-N ARQ, Selective-repeat ARQ, and Selective-drop-repeat ARQ.

The stop-and-wait ARQ transmits one frame, waits until an ACK message is received from the receiver, and then sends a next frame and receives a NAK message or retransmits when a timeout is received. The receiving side sends an ACK if there is no error in the received frame and a NAK message otherwise. The go-back-N ARQ transmits a series of frames determined by the window size. The go-back-N ARQ retransmits subsequent frames when a NAK is received or timed out. The receiving side sends an ACK message if there is no error in the received frame, otherwise it sends a NAK message. In selective-repeat ARQ, a transmitter transmits a series of frames determined by a window size, and retransmits only those frames when a NAK is received or timed out from the receiver. The receiving side sends an ACK message if there is no error in the received frame, otherwise it sends a NAK message. In the selective-drop-repeat ARQ, when the relay apparatus retransmits the packet, only the error-free frame is transmitted and the other frame is discarded. The relay does not transmit ACK or NACK to other terminal devices, but merely relays. The access point and the terminal device, which are the starting point and destination of the packet, perform selective-repeat.

The ARQ in the media access control layer of the present invention uses stop-and-wait ARQ for control data packets and selective-drop-repeat ARQ for actual data packets that are not control data.

Wireless networks are less reliable than wired networks, and more losses occur in the transmission of packets. Therefore, selective-repeat ARQ is used to optimally transmit packets in wireless networks. However, in the case of using a relay device, when the relay device merely performs retransmission without checking a frame error, error frames are often transmitted while passing through a plurality of relay devices, thereby reducing network efficiency. Therefore, the relay apparatus selectively retransmits the frame as described above.

On the other hand, the above-mentioned packet relay method can be created by a computer program. Codes and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the program is stored in a computer readable media, and read and executed by a computer to implement a packet relay method. The information storage medium includes a magnetic recording medium, an optical recording medium, and a carrier wave medium.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

As described above, according to the present invention, in constructing a network in a multi-stage in order to solve distance constraints and shadow areas in a wireless network environment, relay devices may be provided by providing a relay function in a terminal device without additional relay devices. Packet relaying can be performed without interference and wireless network can be easily constructed.

In addition, by dividing the size of the transmitted packet into frame units having a predetermined size and retransmitting only an error frame, congestion of the network caused by retransmitting the entire packet can be prevented.

Claims (15)

In the packet relay method in a wireless network, (a) reading a destination address included in the received packet and determining whether the address matches its own address; And (b) If the result of the determination is identical, if the received packet is a control data packet, one frame constituting the control data packet is transmitted first. And retransmitting the frame if timeout occurs due to an error message or an acknowledge message not being received for a predetermined time, and discarding the received packet if it does not match. The method of claim 1, The received packet includes a header field for recording a source address, a destination address, and a final destination address; And data fields, And the data field is divided into frames of a predetermined size. delete The method of claim 1 or 2, wherein step (b) If the result of the determination is identical, if the received packet is an actual data packet, transmitting only an error free frame among the frames constituting the data packet, and not transmitting an error frame. In the packet relay apparatus in a wireless network, A determination unit which reads a destination address included in the received packet and determines whether the address matches its own address; And If the result of the determination is correct, if the received packet is a control data packet, one frame constituting the control data packet is transmitted first, and if an acknowledgment message is received from the receiving end, the next frame is sent. And a relay unit that transmits the frame again when timeout occurs because it has not received an acknowledgment message or an acknowledgment message for a predetermined time, and discards the received packet if it does not match. The method of claim 5, The received packet includes a header field for recording a source address, a destination address, and a final destination address; And data fields, And the data field is divided into frames of a predetermined size. delete The method of claim 5 or 6, wherein the relay unit If the result of the determination matches, if the received packet is an actual data packet, only an error-free frame is transmitted among the frames constituting the data packet, and the error-free frame is not transmitted. delete delete In the packet relay method, If the packet to be relayed is a control data packet, one frame constituting the control data packet is transmitted first, and when the receiving side receives an acknowledgment message that the received data is received without error, the next frame is sent, an error message or an acknowledgment message for a certain time If the time-out is not received, the frame is transmitted again. If the packet to be relayed is an actual data packet, only an error-free frame is transmitted among the frames constituting the data packet, and an error-free frame is not transmitted. For cameras connected to a wireless network, A network interface unit including a physical layer processing unit and a media access control layer processing unit; A determination unit which reads the destination address included in the packet received through the network interface unit and determines whether the address matches its own address; And If the result of the determination is correct, if the received packet is a control data packet, one frame constituting the control data packet is transmitted first, and if an acknowledgment message is received from the receiving end, the next frame is sent. And a relay unit that transmits the frame again when timeout occurs because it has not received an acknowledgment message or an acknowledgment message for a predetermined time, and discards the received packet if it does not match. The method of claim 12, The received packet includes a header field for recording a source address, a destination address, and a final destination address; And data fields, And the data field is divided into frames of a predetermined size. delete The method of claim 12 or 13, wherein the relay unit If it is determined that the received packet is an actual data packet, only a frame having no error is transmitted among the frames constituting the data packet, and a frame having an error is not transmitted.

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