KR100996672B1 - Image transfer method in wireless sensor network - Google Patents

Abstract

By transmitting the image data in consideration of the remaining buffer of the upper sensor node (parent node) in the wireless sensor network, packet loss caused by the buffer overflow is prevented, and data is transmitted only through the already selected path during image data transmission. Disclosed is a method of transmitting image data in a wireless sensor network which enables continuous reception of image data by transmitting.

In the disclosed wireless sensor network, an image data transmission method includes: requesting buffer information from a lower sensor node (child node) to transmit image data from an upper sensor node (parent node); Providing buffer information to the lower sensor node at an upper sensor node that has received the buffer information; And transmitting the image data to be transmitted to the upper sensor node in consideration of the provided buffer information at the lower sensor node.

Wireless sensor network, RAIT, image data transmission protocol

Description

Image transfer method in wireless sensor network

The present invention prevents packet loss caused by buffer overflow by transmitting image data in consideration of the remaining buffer of the upper sensor node (parent node) in the wireless sensor network, and selects a path already selected during image data transmission. The present invention relates to a method of transmitting image data in a wireless sensor network in which continuous image data can be received by transmitting data only through the network.

In general, wireless sensor networks are one of the technologies that are being actively studied around the world as the human-centered ubiquitous paradigm is expanded. Recently, the WMSN (Wireless Multimedia Sensor Network) field for utilizing multimedia data using a sensor network network has been attracting attention due to hardware performance improvement of CMOS cameras and sensor nodes. Using WMSN, it is expected that the sensor nodes can be used to collect multimedia data from inaccessible areas, thereby increasing the usable area of the sensor network.

To this end, a mechanism for smoothly transmitting multimedia data such as video and audio using a wireless network of sensor nodes must be ensured. However, in order to transmit multi-kilobytes of multimedia data using narrow network bandwidth and low specification sensor nodes, various situations (such as node failure and network error) need to be considered. Links in wireless networks are greatly affected by radio wave interference and environmental factors.

Looking at the image data transmission protocol in the conventional wireless sensor network as follows.

PSFQ and RMST, which are known as techniques for maintaining data reliability in wireless communication, are designed to minimize overhead caused by retransmission using NAK (Negative Acknowledgment) and ARQ (Automatic Repeat Request). In a conventional wireless network, if a link error occurs, the overhead does not occur much even when retransmitted by ARQ method, but packet retransmission in a sensor network with a large energy constraint generates a large energy consumption and is not suitable. In addition, frequent retransmissions make normal data transfer difficult due to memory size limitations with small receive queues.

In addition, when image data is transmitted using a multihop routing protocol, a buffer overflow occurs and packet loss occurs. The reason is that each node has a small size of memory because it has a low hardware specification. Nodes that receive data through multiple paths generate network traffic due to the small buffer size, and the packet loss occurs because the multi-hop routing algorithm solves this by dropping received packets. In addition, the sensor node has a short lifespan due to the use of a small battery, and also has a disadvantage in that the probability of being damaged by physical shock increases when collecting data in an external environment.

In addition, FEC (Forward Error Correction) uses an error correction code to recover data errors. FEC-based UEP (Unequal Error Protection) for image data transmission reduces errors in wireless communication and enables effective transmission. When a packet loss is detected, the FEC algorithm applies the FEC code to recover important data. However, using FEC, it is difficult to recover the entire packet when it is lost.

Next, in case of transmitting image data through the multi-path image data transmission protocol, since the same data is transmitted to two sensor nodes, retransmission due to packet loss caused by communication error or node failure is minimized. However, using this partitioning scheme has the advantage of maintaining a certain level of image data quality in the event of a link channel degradation and node error, while causing a disadvantage of excessive network traffic and energy consumption.

Accordingly, the present invention has been proposed to solve various problems occurring in the conventional wireless sensor network as described above.

The problem to be solved by the present invention is to implement a reliable asynchronous image transfer protocol (RAIT) protocol for controlling the flow of image data using a Token-Bucket method, thereby preventing a queue overflow of the parent node The present invention provides a method of transmitting image data in a wireless sensor network in which image data transmission is maintained by eliminating loss of image data packets caused by memory size.

Another object of the present invention is to provide a method of transmitting image data in a wireless sensor network that allows continuous image data reception by transmitting data only through a path already selected during image data transmission.

The "image data transmission method in a wireless sensor network" according to the present invention for solving the above problems,

A method for transmitting image data between sensor nodes in a wireless sensor network having a tree structure,

Requesting buffer information from an upper sensor node (parent node) for a lower sensor node (child node) to transmit image data;

Providing buffer information to the lower sensor node at an upper sensor node that has received the buffer information;

And transmitting the image data to be transmitted to the upper sensor node in consideration of the provided buffer information at the lower sensor node.

In the above, the lower sensor node,

By analyzing the buffer information provided from the upper sensor node, the routing path is temporarily fixed to prevent another upper sensor node from being selected during image data transmission when a buffer exists.

In the above, when the lower sensor node lacks a token indicating a buffer amount during image data transmission, the lower sensor node may stop transmitting the image data and request a token from the upper sensor node.

When the lower sensor node receives a token from the upper sensor node in a state in which image data transmission is stopped, the lower sensor node resumes image data transmission.

In the above, the lower sensor node,

An application (APP) layer for executing image data transfer;

A RAIT layer for requesting a buffer from the upper sensor node and receiving a buffer from the upper sensor node when image data transmission is requested from the application layer;

A multi-hop layer configured to set a routing path when transmission image data is transmitted from the RAIT layer, and temporarily fix the routing path during transmission of the image data;

When receiving the buffer from the RAIT layer to the upper sensor node, considering the buffer includes a queue layer for transmitting the image data transmitted from the multi-hop layer to the upper sensor node.

In addition, the upper sensor node,

When a buffer is requested from the lower sensor node, it checks its current state and provides a buffer to the lower sensor node when it is not transmitting its own image data and not forwarding image data of another sensor node. do.

In addition, when the upper sensor node provides a buffer to the lower sensor node, the upper sensor node switches to an image data forwarding state and receives only image data transmitted from the lower sensor node.

In addition, the upper sensor node,

An application layer for executing image data transfer;

When a buffer is requested from the lower sensor node, it checks its own state, and if it is not transmitting its own image data and not forwarding image data of another sensor node, the remaining buffer amount is obtained through the queue layer, and the lower sensor is obtained. A RAIT layer provided to the node to control traffic;

A multi-hop layer configured to set a routing path in association with the RAIT layer and to receive only image data transmitted from the lower sensor node when a buffer is provided to the lower sensor node;

And a queue layer for transmitting image data of the lower sensor node transferred from the multi-hop layer.

The upper sensor node in the above,

When image data is transmitted from the lower sensor node,

Checking the sequence header in the multi-hop layer and delaying transmission by blocking the queue layer if it is the first image;

Releasing blocking of the queue layer when performing a forwarding initialization in the RAIT layer, requesting an image data forwarding from another higher sensor node, and receiving a message capable of forwarding image data from the other upper sensor node; ;

When blocking is canceled in the queue layer, image data received from a lower sensor node is transmitted to the other upper sensor node, and if the token is insufficient while forwarding the image data, the forwarding of image data is paused, and the RAIT layer Requesting a token.

The RAIT layer requests a buffer to the other upper sensor node when a token request is generated from the queue layer during image data forwarding, and forwards the image data by providing it to the queue layer when a buffer is received from the other upper sensor node. Characterized in that to control the traffic to resume.

According to the present invention described above, by implementing a Reliable Asynchronous Image Transfer Protocol (RAIT) protocol that controls the flow of image data using the Token-Bucket method, it is possible to prevent the queue overflow of the parent node (Queue Overflow). Therefore, there is an advantage that can eliminate the loss of the image data packet caused by the small memory size, and this advantage has the advantage of ensuring the reliability of image data transmission in the wireless sensor network.

In addition, there is an advantage in that continuity can be given to the reception of the image data by transmitting the data only through the already selected path during image data transmission.

Hereinafter, described in detail with reference to the accompanying drawings a preferred embodiment of the present invention. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

1 illustrates a configuration of a wireless sensor network to which the present invention is applied, and includes a sensor field including a user terminal 100, an external network 200, a sink node 300, and a plurality of sensor nodes 500. 400).

The sensor field 400 has a plurality of sensor nodes 500 arranged in a tree structure. A plurality of sensor nodes 500 constituting the sensor field 400 includes a wireless platform for supporting data communication with the outside, a processor platform for processing data, and a memory for storing various data.

The sink node 300 connects the sensor field 400 with an external network 200 including a tactical internet through a private land, a mobile communication network, or a wired / wireless network, and includes a gateway or a base station. Also called a station. In the embodiment of the present invention, the sink node 300 connecting the sensor field 400 and the external network 200 is illustrated as a single unit, but may be configured as a plurality of sink nodes in the wireless sensor network.

In the wireless sensor network configured as described above, data generated in the sensor field 400 including the plurality of sensor nodes 500 is provided to the external network 200 through the sink node 300, and the user is provided with the external network 200. The various types of data provided by the sensor field 400 are provided through the user terminal 100 connected to the terminal.

4 shows the overall structure of the image data transmission method in the wireless sensor network according to the present invention. When the image sensor forwarding is requested from the lower sensor node 510 and the lower sensor node 510, the image sensor is largely transmitted. It is composed of an upper sensor node 520 that checks its own state and, when the image data forwarding is possible, receives the image data transmitted from the lower sensor node 510 and forwards it to another upper sensor node.

Here, the lower sensor node 510 and the upper sensor node 520 mean the sensor node 500 provided in the sensor field 40 of FIG. 1, and simply lower the sensor node that transmits image data to the upper sensor node. The sensor node was called a sensor node, and a sensor node that receives image data transmitted from a lower sensor node and forwards it to another upper sensor node is called an upper sensor node. In the drawing, a child node refers to a lower sensor node and a parent node refers to an upper sensor node.

The lower sensor node 510 includes an application (APP) layer 511 for executing image data transmission; When image data transmission is requested from the application layer 511, the RAIT layer requests buffer information (token) to the upper sensor node 520, receives a buffer from the upper sensor node 520, and controls traffic. 512; A multi-hop layer 513 for setting a routing path when transmission image data is transmitted from the RAIT layer 512 and temporarily fixing the routing path during the transmission of the image data; When receiving the buffer from the RAIT layer 512 to the upper sensor node 520, the queue layer for transmitting the image data transmitted from the multi-hop layer 513 to the upper sensor node 520 in consideration of the buffer ( 514).

The upper sensor node 520 includes an application layer 521 for executing image data transmission; When a buffer is requested from the lower sensor node 510, the controller checks its own state and, if it is not transmitting its own image data and not forwarding image data of another sensor node, the remaining buffer (token) through the queue layer 524. A RAIT layer 522 for acquiring) and providing the same to the lower sensor node 510 to control traffic; In the case of setting a routing path in cooperation with the RAIT layer 522 and providing a buffer to the lower sensor node 510, the multi-hop layer 523 receiving only image data transmitted from the lower sensor node 510. Wow; The queue layer 524 transmits the image data of the lower sensor node 510 transmitted from the multi-hop layer 523.

Hereinafter, the image data transmission method in the wireless sensor network according to the present invention configured as described above will be described in detail.

The most important consideration when implementing the image data protocol is maintaining the reliability of image data transmission. Typical sensor nodes use low-end hardware, which means that they have a small receive queue. For this reason, when a large amount of multimedia data is transmitted, there is a high probability that a queue overflow occurs on the receiving side.

To prevent queue overflow, the RAIT layers 512 and 522 use a Token-Bucket technique.

2A and 2B disclose an example of the operation of the Token-Bucket.

Token in Token-Bucket means one byte or packet and is the minimum unit for flow control of data transmission. In this way, the RAIT layers 512 and 522 take into account network traffic conditions and have a mechanism to transmit image data only when they can communicate. The criterion for determining network congestion is the token size allocated from the parent node, and the child node stops data transmission if no token of the parent node remains. This operation requires control of the multihop layers 513 and 523 and queue layers 514 and 524 in the RAIT layer. The RAIT layer sends a control message necessary for image data transmission to the parent node and retrieves the token of the parent node. The child node limits the number of transmittable packets to the size of the token as shown in FIGS. 2A and 2B, and reduces the size of the allocated token every time one packet is transmitted. If no allocated tokens remain, the transfer is paused and the parent node is requested again. If there is no queue (buffer) available in the parent node and the packet is received, the data will not be stored in the queue layer and will be dropped. However, this behavior does not occur if the child node considers the token of the parent node.

In RAIT, a control message and an image data transmission message having the format shown in FIG. 3 are used. In FIG. 3, the message shown at the top is a control message, and the message shown at the bottom is an image data transmission message. Each message is distinguished using a flag, and a sequence (seq) indicating an order of image data and srcAddr indicating a node number of an image data transmission sensor are used in a common message.

Next, the RAIT uses a table-driven multi-hop layer 513 and 523. When routing begins, the sensor node sends a routing message to neighboring nodes in a broadcast manner, and the node that receives the routing message from another node updates the routing table based on the routing message. The estimator of the multi-hop layer periodically selects the most appropriate node from the routing table and selects it as the parent node. Metrics for selecting a parent node are Hop-Count and Link-Quality, which are stored together with the sensor node number in the routing table. The multi-hop layer of this structure takes a lot of time to configure when it does not have a proper routing table to select a parent node, but if the routing is stabilized, it is possible to transmit a stable packet in an environment where there is no significant change in topology.

On the other hand, the sensor network, which is a combination of node and link, requires a traffic control technique to prevent data loss. Traffic control adjusts the amount of transmission so that when data is transmitted from the transmitting node to the destination node, the data is not processed too quickly or too slowly at the destination node. Congestion control is a method for avoiding or resolving data collisions when transmitting data from two or more nodes. RAIT uses a drop-tail (FIFO) based queuing technique for traffic congestion and congestion control. Drop-Tail-based queuing uses a method of dropping received packets when the receive queue is full, and packet loss due to drop in queue layers 514 and 524 because image data cannot be decoded normally when there is a loss. This should not happen. Since the RAIT transmits data in consideration of the token size of the parent node queue layer 524, the packet drop is not caused by many data transmissions.

In the present invention, image data is transmitted through a process of transmitting image data, a process of receiving image data, and a process of forwarding image data.

First, referring to the process of transmitting image data, as shown in FIG. 5, the application layer 511 transfers the image data array to the RAIT layer 512 when image data sampling is completed (Send Image). The RAIT layer 512 transmits a REQ_INIT message for image data transmission request to the parent node 520 (Send RREQ), and the parent node 520 transmits the image data or REP_INIT including a token if it is not forwarding from another node. Returns a message indicating the status of image data transfer (Reply RREP). If the REP_INIT message arrives at the child node 510 normally, the RAIT layer 512 notifies the multi-hop layer 513 of the current state so as not to select another parent node during image data transmission. This is a method to continuously transmit image data, and resets to its original state when the transmission is completed. If the token obtained from the parent node is greater than zero, transmission of image data is started through the queue layer 514 (Send IMG data).

In TinyOS, which has the characteristics of an event-based operating system, it is common to use periodic timer events to transmit data collected in the environment. However, using a timer event to transfer image data is a bad idea. Image data transmission is the key to sending a large amount of data at the fastest speed, because using a periodic timer event is difficult to set the optimal period. Using a large timer period will slow down the data rate, and using a timer period that is too small may cause the transfer command to fail in some cases. This is because TinyOS executes some commands in a split-phase manner. If another kind of event is executed while executing a specific event, the second event is forced to terminate. Using the send command generates a sendDone event, which may conflict with a timer event. In order to prevent split-phase and improve the transfer rate, it is wise to send data by calling the transfer function on the sendDone event.

Meanwhile, if the token is insufficient during the transmission of the image data, the transmission of the image data is stopped, and the RAIT layer 512 transmits a REQ_TOKEN message to request a token from the parent node 520 (Send RREQT). The parent node 520 returns the token through the REP_TOKEN message, and the child node 510 resumes the transmission of the image data if the child node 510 acquires the token greater than zero, and retries the transmission of the REQ_TOKEN message at random intervals. When the image data transmission is completed, the message is sent to the parent node 520 to terminate the image data transmission.

Next, the process of receiving image data is as follows.

A sequence diagram for receiving image data using the RAIT layer is shown in FIG. 6. In FIG. 6, reference numeral 530 denotes an upper sensor node for receiving image data from a child node, and substantially refers to a parent node.

When the RAIT layer 532 of the parent node 530 receives the REQ_INIT message transmitted from the child node 540 (Send RREQ), it checks its current state and is not transmitting image data or is forwarding from another node. Otherwise, a request for a token representing remaining buffer information is requested to the queue layer 534 (require token), and when a token is obtained from the queue layer 534 (return token), image data can be received by the child node 540. Reply RREP. The REP_INIT message includes a token obtained from the queue layer 534. The multi-hop layer 533 is then notified of the image data forwarding state, and the multi-hop layer 533 only receives data transmitted from the currently configured child node.

If the REQ_TOKEN message for requesting a token arrives from the child node 540 while receiving image data, the token of the queue layer 534 is obtained and transmitted to the child node 540. When the REQ_END message arrives from the child node 540, it means that image data transmission is completed, so the multi-hop layer 533 is reset and the image data reception is terminated.

Next, the image data forwarding process will be described with reference to FIG. 7. In FIG. 7, reference numeral 570 denotes another upper sensor node (another parent node), reference numeral 550 denotes a lower sensor node, and reference numeral 560 indicates when receiving image data transmission from a lower sensor node (child node). An upper sensor node transmitted to another upper sensor node 570. FIG. The upper sensor node 560 is the same as the parent node 520 in FIG. 4, and the lower sensor node 550 is the same as the child node 510 in FIG. 4. It is only.

When the image data arrives from the child node 550, the current node (parent node) 560 must perform a special operation for forwarding the image data to another parent node 570.

To this end, the multi-hop layer 563 checks the sequence header of the received image data, and if it is the first image data, blocks the queue layer 564 to block transmission delay. The queue layer 564 serves as a receive queue for receiving and transmitting at the same time. The packet waiting in the queue layer 564 waits until the neighboring node to be downstream is enabled. Since the child node 550 transmits data in consideration of the size of the current node 560 queue, there is no loss due to the drop of the received image data. Next, a forwarding initialization command is transmitted to the RAIT layer 562 and a forwarding request is sent by sending a REQ_FORWARD message to the parent node 570 (Send RREQF). When the parent node 570 assigns a token and sends a REP_FORWARD message to indicate that image data forwarding is possible (Reply RREPF), the RAIT layer 562 enables the queue (unBlock) and starts image data forwarding to the parent node. . At this time, the token received from the REP_FORWARD message is transmitted to the queue layer 564 to prevent the data transmitted to the parent node from being dropped during actual data transmission. If the token is insufficient, blocking the queue stops forwarding, and acquires the token of the parent node through the RAIT layer 562 (Send RREQT). The reason for managing tokens in image data is to prevent token misoperation because event tokens are executed before general commands because tokens are managed in sendDone of queue.

When the image data transmission of the child node is completed and the REQ_END message is received at the RAIT layer 562, the multi-hop layer 563 and the queue layer 564 notifies the image data transmission end state. The queue layer 564 checks the sequence of the image data, and if data forwarding is completed, transmits a REQ_END message to the RAIT layer 562. The checked RAIT layer 562 transmits a REQ_END message to the parent node. Confirm that forwarding is complete.

Meanwhile, in order to examine the performance of the RAIT proposed by the present invention, the difference of image data rate with the MintRoute component, a table-driven multi-hop component provided by TinyOS, was examined. To this end, we used TOSSIM and TinyViz, a simulator, and Tython, a scripting language. Tython is a scripting language composed of Java and Python used in TOSSIM. It provides various functions such as interlocking with TOSSIM to control sensor nodes or getting data values of sensor applications.

In the experiment, 100 sensor nodes were arranged in a grid, and the transmission rate of image data transmitted from eight randomly designated image data nodes to the sink node was examined. Each image data is composed of 36 packets, and it is assumed that the transmission of the image data is successful when the complete data of the image data is completed.

The result of image data transmission using the RAIT and the multi-hop component is shown in FIG. 8. The image data using RAIT has a near 100% data rate, but the data rate using MintRoute component is only about 50%.

The reason for this result is as follows.

The first reason is that data transmitted by multiple image data nodes is lost while arriving at the sink node. The reason is that the sensor node does not consider the data capacity of the parent node. In this experiment, it occurred by transmitting data simultaneously to one parent node selected from several nodes. In particular, this phenomenon occurs in the sensor node that is located in the hop close to the sink node. Network traffic due to this problem adds to data loss due to queue overflow.

The second reason is that the routing path is arbitrarily changed during image data transmission. Image data should be transmitted to sink nodes in sequence. If the route changes, the probability of packet loss is increased without reaching the final destination sink node.

However, in the case of RAIT, which is an image data transmission method proposed by the present invention, it can be seen that image data loss caused by network traffic can be prevented through a token-bucket method, and thus image data in various conditions of multi-hop can be prevented. It can be seen that the reliability can be guaranteed.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

1 is a schematic configuration diagram of a wireless sensor network system to which the present invention is applied.

2A and 2B are explanatory diagrams for explaining a Token-Bucket operation scheme according to the present invention.

3 is a packet mapping diagram of the RAIT layer in the present invention.

4 is a conceptual diagram of a method of transmitting image data in a wireless sensor network according to the present invention;

5 is a diagram illustrating a process of transmitting image data of FIG. 4.

6 is a diagram illustrating a process of receiving image data of FIG. 4.

FIG. 7 is a diagram illustrating an image data forwarding process of FIG. 4. FIG.

Figure 8 is a graph of the experimental results of simulating the image data transmission rate in the present invention.

<Explanation of symbols for the main parts of the drawings>

510... Child sensor node (child node)

511... Application layer

512... RAIT layer

513... Multihop layer

514... Cue layer

520... Parent sensor node (parent node)

521... Application layer

522... RAIT layer

523... Multihop layer

524... Cue layer

Claims (10)

A method for transmitting image data between sensor nodes in a wireless sensor network having a tree structure, Requesting buffer information from an upper sensor node (parent node) for a lower sensor node (child node) to transmit image data; Providing buffer information to the lower sensor node at an upper sensor node that has received the buffer information; And transmitting the image data to be transmitted to the upper sensor node in consideration of the provided buffer information at the lower sensor node. The lower sensor node, An application (APP) layer for executing image data transfer; A Reliable Asynchronous Image Transfer (RAIT) layer requesting a buffer from the upper sensor node when the image data transmission is requested from the application layer and receiving the buffer from the upper sensor node; A multi-hop layer configured to set a routing path when transmission image data is transmitted from the RAIT layer, and temporarily fix the routing path during transmission of the image data; When receiving a buffer from the RAIT layer to the upper sensor node, the image in the wireless sensor network comprising a queue layer for transmitting the image data transmitted from the multi-hop layer to the upper sensor node in consideration of the buffer Data transfer method. The method of claim 1, wherein the lower sensor node, And analyzing the buffer information provided from the upper sensor node, and temporarily fixing a routing path to prevent selecting another upper sensor node during image data transmission if a buffer exists. The method of claim 2, wherein the lower sensor node, If the token indicating the buffer information is insufficient during the transmission of the image data, the image data transmission method in the wireless sensor network, characterized in that to stop the transmission of the image data and request the token to the upper sensor node. The method of claim 3, wherein the lower sensor node, And transmitting the image data when the token is received from the upper sensor node in a state in which the image data transmission is stopped. delete The method of claim 1, wherein the upper sensor node, When a buffer is requested from the lower sensor node, it checks its current state and provides a buffer (token) to the lower sensor node when it is not transmitting its own image data and not forwarding image data of another sensor node. Image data transmission method in a wireless sensor network, characterized in that. The method of claim 6, wherein the upper sensor node, When the buffer is provided to the lower sensor node, the image data transmission method of the wireless sensor network, characterized in that to switch the operation to the image data forwarding state receives only image data transmitted from the lower sensor node. The method of claim 7, wherein the upper sensor node, An application layer for executing image data transfer; When a buffer is requested from the lower sensor node, it checks its own state, and if it is not transmitting its own image data and not forwarding image data of another sensor node, the remaining buffer amount is obtained through the queue layer, and the lower sensor is obtained. A RAIT layer provided to the node to control traffic; A multi-hop layer configured to set a routing path in association with the RAIT layer and to receive only image data transmitted from the lower sensor node when a buffer is provided to the lower sensor node; And a queue layer transmitting image data of the lower sensor node transmitted from the multi-hop layer. The method of claim 8, wherein the upper sensor node, When image data is transmitted from the lower sensor node, Checking the sequence header in the multi-hop layer and delaying transmission by blocking the queue layer if it is the first image; Releasing blocking of the queue layer when performing a forwarding initialization in the RAIT layer, requesting an image data forwarding from another higher sensor node, and receiving a message capable of forwarding image data from the other upper sensor node; ; When blocking is canceled in the queue layer, image data received from a lower sensor node is transmitted to the other upper sensor node, and if the token is insufficient while forwarding the image data, the forwarding of image data is paused, and the RAIT layer A method of transmitting image data in a wireless sensor network, comprising: requesting a token. 10. The method of claim 9, wherein the RAIT layer requests a buffer to the other higher sensor node when a token request is generated from the cue layer during forwarding of image data, and if it receives a buffer from the other higher sensor node, the RAIT layer sends the request to the queue layer. And controlling traffic so that forwarding of image data can be resumed.

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