KR100893041B1 - Method of the adaptive media access control in wireless sensor network - Google Patents

Abstract

The present invention relates to an adaptive wireless link connection control method of a sensor network node and a computer-readable recording medium recording a program for realizing the method. More particularly, the present invention relates to unnecessary node energy consumption due to long preamble overhearing. It defines a data frame containing a preload frame including consecutive preload messages to reduce the number of channels between nodes located on the routing path to ensure fast data transmission in real time in consideration of data transmission frequency and low duty cycle. An adaptive radio link connection control method of a sensor network node that performs data transmission / reception while adjusting a sampling time, and a computer-readable recording medium having recorded thereon a program for realizing the method.

To this end, the present invention, in the adaptive radio link access control method of the sensor network node, the process of changing the channel sampling time between nodes on the routing path, as the first node bursts the data sensed by the first node corresponding to the burst; Calculating a request sampling time based on the data rate; Sending, by the first node, a preload frame to a second node on a routing path during a preset preload time as channel activity by another node on the network is not detected; After the first node completes the transmission of the preload frame, loading the calculated request sampling time and corresponding sensing data in a data frame and transmitting the data to the second node; And as the second node receives the data frame from the first node, changing its channel sampling time to a request sampling time inserted in the data frame.

Sensor network, long preamble overhearing, preload message, preload frame, data frame, ACK frame, data transmission frequency, low duty cycle, data rate, preload time, channel sampling time

Description

Adaptive wireless link access control method of sensor network node {Method of the adaptive media access control in wireless sensor network}

The present invention relates to an adaptive wireless link connection control method of a sensor network node and a computer-readable recording medium recording a program for realizing the method. More particularly, the present invention relates to unnecessary node energy consumption due to long preamble overhearing. It defines a data frame containing a preload frame including consecutive preload messages to reduce the number of channels between nodes located on the routing path to ensure fast data transmission in real time in consideration of data transmission frequency and low duty cycle. An adaptive radio link connection control method of a sensor network node for performing data transmission / reception while adjusting a sampling time, and a computer-readable recording medium having recorded thereon a program for realizing the method.

A wireless sensor network (WSN) refers to a network that wirelessly delivers specific information collected by a sensor provided between nodes to an external device. A representative protocol used in such a wireless sensor network is a B-MAC (Media Access Control) protocol for ensuring data transmission quality (QoS).

The B-MAC protocol refers to an asynchronous based MAC protocol that does not use a beacon message in consideration of the significant consumption of node energy due to control overhead in synchronizing nodes.

In a wireless sensor network environment where a small amount of data (also called low data) occurs (transmits / receives) frequently, the asynchronous-based B-MAC protocol consumes less node energy and transmits more data than the synchronous MAC protocol. There is an advantage that happens quickly. For example, in the B-MAC protocol, there is no energy consumption that a node uses to synchronize and thus the active period is shortened.

1 is a diagram illustrating an embodiment of a data transmission / reception process of a known B-MAC protocol.

As shown in FIG. 1, in the known B-MAC protocol, all nodes (the transmitting node and the receiving node respectively) repeatedly perform the active mode and the sleep mode. Here, the sum of the sleep mode execution time (hereinafter referred to as "sleep time") and the active mode execution time (hereinafter referred to as "active time") for one node is referred to as "one cycle." In addition, the value obtained by multiplying "100" by the time divided by one period [Active_period + Sleep_period] by the active time [Active_period] is defined as a duty cycle [Duty cycle], which is expressed by Equation 1 below.

On the other hand, as mentioned earlier, in the B-MAC protocol, the node operates asynchronously, which means that one cycle is shortened due to the short active time when there is a fixed duty cycle, thereby enabling faster data transmission. do.

In the B-MAC protocol, instead of synchronizing with a beacon message, each node has a different active schedule with respect to the active mode. In order to ensure data communication of each node, a long preamble is transmitted before data transmission. send a preamble over the network. Here, the time for which the transmitting node sends the long preamble is set slightly longer than the sleep time of the receiving node.

That is, the receiving node receives the long preamble at the time when it wakes up from the sleep mode and transitions to the active mode. In the case where the long preamble on the channel is received, the receiving node receives the sleep mode even after a short channel sampling time. It will continue to be in active mode without transitioning. This technique is called Low Power Listening (LPL).

However, in the conventional B-MAC protocol as described above, there is an advantage of not synchronizing nodes through beacon messages, but it causes a fatal problem due to sending a long preamble on the network.

For example, in the conventional B-MAC protocol, all nodes existing in the one-hop of a transmitting node on the network wake up from the sleep mode and transition to the active mode to detect channel activity only when channel sampling is performed. This is a problem in that all nodes in the one-hop of a transmitting node do not return to the sleep mode even after performing channel sampling, and have to maintain the active mode for a long time. Accordingly, there is a problem that the energy consumption of the node is unnecessarily weighted.

That is, in the conventional B-MAC protocol, a problem of node energy consumption occurs due to long preamble overhearing, and the consumed node energy is proportional to the long preamble time and the density of the nodes. This will be described with reference to FIG. 2.

FIG. 2 is a diagram illustrating an embodiment of a node energy consumption problem due to long preamble overhearing of a known B-MAC protocol.

As shown in FIG. 2, in the conventional B-MAC protocol, other nodes except for the transmitting node should receive the destination address of the data header portion following the long preamble of the transmitting node, but the node corresponds to the destination. It is recognized that the receiving node is a node, and thus other nodes except the receiving node may transition to the sleep mode. That is, due to the long preamble of the transmitting node, not only the receiving node corresponding to the destination but also other nodes in the one-hop of the transmitting node needlessly increase energy consumption due to long preamble overhearing. .

Meanwhile, in the conventional B-MAC protocol, there is no definition about how to adjust the long preamble. For example, in the conventional B-MAC protocol, the data transmitted by each node on the network has the same time to reach one-hop.

However, even when a particular transmitting node suddenly has a large amount of data to transmit (occurring burst data), like other nodes, it has no choice but to send data as much as one-hop arrival time, which means that data transmission on the network cannot be performed quickly. it means. As a result, the conventional B-MAC protocol induces high data transmission latency in a wireless sensor network that transmits and relays data through multi-hops.

Accordingly, the present invention has been proposed to solve the above problems, and defines a data frame in which a preload frame including a continuous preload message is inserted to reduce unnecessary node energy consumption due to long preamble overheard. Adaptive wireless link access of sensor network nodes to perform data transmission / reception while adjusting channel sampling time between nodes located on the routing path to ensure fast data transmission in real time, taking into account transmission frequency, low duty cycles, etc. It is an object of the present invention to provide a computer-readable recording medium recording a speed control method and a program for realizing the method.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned above can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

A first method of the present invention for achieving the above object, in the adaptive radio link connection control method of a sensor network node, transmitting a data frame from a transmitting node to a receiving node, the data frame is a predetermined number of consecutive Preload frame consisting of a preload message of; Data transmitted from the transmitting node to the receiving node; And a request sampling time for changing a channel sampling time of the receiving node, wherein each of the preload messages comprises: a preamble including synchronization information between the transmitting node and the receiving node; A destination address representing the receiving node; And a duration indicating a remaining time before the transmitting node transmits data.

On the other hand, according to the second method of the present invention, in the adaptive radio link connection control method of the sensor network node, the data transmission process of the transmitting node is a predetermined number of pre-consecutive operations as channel activity by another node is not detected. A preload frame transmission step of transmitting a preload frame including a load message on a network; A data frame transmission step of transmitting the data sensed by the self in the data frame and transmitting the data onto the network after completion of the preload frame transmission; And after receiving the ACK frame from the corresponding receiving node within a predetermined time limit after transmitting the data frame, completing the corresponding data transmission.

The second method of the present invention may further include recording a reception node address corresponding to a destination of the data frame and a request sampling time inserted into the data frame in its preload table.

Further, the second method of the present invention further comprises the step of setting a value of a timer set to a predetermined value to be driven toward “0” from the time when the receiving node address and the request sampling time are recorded in the preload table. Include.

In addition, the second method of the present invention, before the next preload frame transmission, querying whether there is a receiving node address corresponding to the destination in the preload table; And as a result of the preload table query, if there is a corresponding receiving node address, transmits the next preload frame onto the network according to a request sampling time matched to the corresponding receiving node address of the preload table, and And if the receiving node address does not exist, transmitting the next preload frame onto the network at a preset request sampling time.

The second method may further include deleting a reception node address and a request sampling time matched to a field having a timer value of “0” in the preload table.

On the other hand, the present invention, the transmitting node having a processor, the function of transmitting a preload frame on the network containing a predetermined number of preload messages in sequence as the channel activity by the other node is not detected; A function of inserting a request sampling time into a data frame and transmitting it on the network as the frequency of data sensed by the user changes; And a computer-readable recording medium having recorded thereon a program for realizing the function of completing the data transmission upon receiving the ACK frame from the corresponding receiving node within a predetermined time limit after transmitting the data frame.

The present invention also provides a function of recording a reception node address corresponding to a destination of the data frame and a request sampling time inserted into the data frame in its preload table; And a program for further realizing a function of setting a value of a timer set to a predetermined value to be driven toward " 0 " from the time when the receiving node address and the request sampling time are recorded in the preload table. Provide a recording medium.

In addition, the present invention, before the next preload frame transmission, a function for inquiring whether there is a receiving node address corresponding to the destination in the preload table; And as a result of the preload table query, if there is a corresponding receiving node address, transmits the next preload frame onto the network according to a request sampling time matched to the corresponding receiving node address of the preload table, and If a receiving node address does not exist, a computer-readable recording medium having recorded thereon a program for further realizing the function of transmitting the next preload frame onto the network in accordance with a preset request sampling time is provided.

The present invention also provides a computer-readable recording medium having recorded thereon a program for further realizing a function of deleting a reception node address and a request sampling time matched to a field having a timer value of "0" in the preload table. to provide.

On the other hand, in the third method of the present invention, in the adaptive radio link connection control method of the sensor network node, the data reception process of the receiving node transitions from the sleep mode to the active mode at a predetermined channel sampling time to another node. Checking for channel activity by means of; Receiving a preload frame from a corresponding transmitting node as determined to be busy by the channel activity check result; Checking whether a destination address in the preload message included in the received preload frame matches its address; Checking a duration in a preload message included in the preload frame and returning to a sleep mode according to the address check result according to its address; And transitioning from a sleep mode to an active mode after receiving the confirmed duration, receiving a data frame from the transmitting node.

The third method of the present invention may further include transmitting an ACK frame including its own address to the transmitting node after completing the data frame reception.

In addition, the third method of the present invention further includes a channel sampling table recording step of recording the address of the transmitting node and the request sampling time in its channel sampling table as the request sampling time is inserted into the data frame. Include.

In addition, the third method of the present invention is set so that the value of a timer set to a predetermined value is driven toward “0” from the time when the address of the transmitting node and the request sampling time are recorded in the channel sampling table. It further comprises a step.

In addition, the third method of the present invention further includes deleting the transmission node address and the request sampling time matched to the field in which the timer value of the channel sampling table is "0".

The third method of the present invention also transitions from a sleep mode to an active mode at every request sampling time recorded in the channel sampling table to check whether there is channel activity by another node including the transmitting node, and then moves from the corresponding transmitting node. The method may further include receiving a preload frame.

On the other hand, the present invention, the receiving node having a processor, a function for checking whether there is channel activity by another node by transitioning from the sleep mode to the active mode at each preset channel sampling time; Receiving a preload frame from a corresponding transmission node according to the busy state as a result of the channel activity check; Checking whether a destination address in a preload message included in the received preload frame matches its own address; A function of checking a duration in a preload message included in the preload frame and returning to a sleep mode according to the address check result according to its own address; And a computer-readable recording medium having recorded thereon a program for realizing a function of receiving a data frame from the transmitting node by transitioning from a sleep mode to an active mode after the confirmed duration.

In addition, the present invention, after completing the reception of the data frame, the function of transmitting an ACK frame containing its address to the transmitting node; And a program for further realizing a channel sampling table recording function of recording the address of the transmitting node and the request sampling time in its channel sampling table as the request sampling time is inserted into the data frame. Provide a recording medium.

The present invention also provides a function of setting a value of a timer set to a predetermined value in advance toward "0" from the time when the address of the transmitting node and the request sampling time are recorded in the channel sampling table; And a computer-readable recording medium having recorded thereon a program for further realizing a function of deleting a transmission node address and a request sampling time matched to a field having a timer value of "0" in the channel sampling table.

In addition, the present invention transitions from the sleep mode to the active mode for each request sampling time recorded in the channel sampling table to check whether there is channel activity by another node including the transmitting node, and the next preload frame from the transmitting node. Provided is a computer readable recording medium having recorded thereon a program for further realizing a receiving function.

On the other hand, according to the fourth method of the present invention, in the adaptive radio link connection control method of the sensor network node, the process of changing the channel sampling time between nodes on the routing path is such that the data sensed by the first node bursts. Calculating a request sampling time based on the corresponding data rate; Sending, by the first node, a preload frame to a second node on a routing path during a preset preload time as channel activity by another node on the network is not detected; After the first node completes the transmission of the preload frame, loading the calculated request sampling time and corresponding sensing data in a data frame and transmitting the data to the second node; And changing its channel sampling time to a request sampling time inserted in the data frame as the second node receives the data frame from the first node.

Further, the fourth method of the present invention further includes changing the preload time to the request sampling time that was sent to the second node as the first node receives the ACK frame from the second node. .

The fourth method of the present invention may further include sending a next preload frame to the second node at the changed preload time by the first node, wherein the first node comprises: the second node; The preload time is set to be relatively longer than the channel sampling time of the node, and the next preload frame is transmitted to the second node.

On the other hand, the present invention, in the sensor network system, the first node bursts the data sensed by the burst (burst), the function of calculating the requested sampling time based on the data rate; Sending, by the first node, a preload frame to a second node on a routing path during a preset preload time as channel activity by another node on the network is not detected; A function of transmitting, by the first node, the calculated request sampling time and corresponding sensing data to the second node after completion of the preload frame transmission in a data frame; And a program for realizing a function of changing a channel sampling time of the second node to a request sampling time inserted in the data frame as the second node receives the data frame from the first node. Provide a record carrier.

The present invention also records a program for further realizing a function of changing the preload time to a request sampling time sent to the second node as the first node receives an ACK frame from the second node. Provide a computer readable recording medium.

The present invention further provides a function of transmitting a next preload frame to the second node by setting the changed preload time relatively longer than a request sampling time sent to the second node. A computer readable recording medium having recorded thereon a program for realization is provided.

As described above, the present invention has an effect of reducing unnecessary node energy consumption due to long preamble overhearing in the wireless sensor network.

In addition, the present invention has the effect of ensuring fast data transmission in real time even in a situation where the data transmission frequency is suddenly increased in the wireless sensor network.

In addition, the present invention has the effect of ensuring low power implementation and fast data transmission of the node by changing the duty cycle of the node according to the data rate.

The above objects, features, and advantages will become more apparent from the detailed description given hereinafter with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention pertains may share the technical idea of the present invention. It will be easy to implement. 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. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, in order to reduce unnecessary node energy consumption due to long preamble overhearing in a wireless sensor network based on the B-MAC protocol, a preload message is defined instead of the existing long preamble. And a transmitting node continuously sends the preload message on the network for a preamble time before data transmission.

In the present invention, the duty cycle of all nodes in the wireless sensor network based on the B-MAC protocol (for example, execution of a target monitor application) for a situation in which the frequency of data transmission is suddenly increased. cycles to ensure fast real data transmission.

The present invention is an improvement on the known B-MAC protocol used in the wireless sensor network, and the basic matters are the same as the B-MAC protocol. For example, the present invention uses an asynchronous method that does not synchronize nodes with a beacon message, uses a low power listening method, and uses an "Unslotted CSMA" method to prevent a data transmission collision.

Then, the following improvements to the known B-MAC protocol, that is, the preload message, preload frame, data frame, and ACK frame proposed by the present invention Let's first look at.

In the present invention, to enable data communication between all nodes repeatedly transitioning between the active mode and the sleep mode as different active schedules, that is, to synchronize with the receiving node before the transmitting node transmits data. Defines a message sent as a preload message.

FIG. 3A is a structure diagram of an embodiment of a preload message according to the present invention, and FIG. 3B is a structure diagram of an embodiment of a preload frame according to the present invention, and FIG. One embodiment structure diagram for a data frame presented in the present invention, Figure 3d is an embodiment structure diagram for an ACK frame proposed in the present invention.

As shown in FIG. 3A, a preload message includes a 4-byte preamble, a 1-byte delimiter, a 4-byte address, and a 2-byte duration. Is done.

In FIG. 3A, the preamble includes chip-to-symbol synchronization information between nodes, the delimiter indicates the beginning of a meaningful message, the address indicates a destination address, and the duration indicates the time remaining before the transmitting node sends data. Indicates.

3B shows a preload frame. The preload frame includes a preload message that is repeated (continuously) in a predetermined number (for example, 10). For example, it can be seen that the preload message has a size of 11 bytes, and the preload frame has a data size of 11 multiples.

In the present invention, the time used by the transmitting node to transmit the preload frame shown in FIG. 3B is defined as a preloads period. That is, in the present invention, the preload time varies variably according to the channel sampling period. The relationship between the preload time and the channel sampling time will be described in detail later.

3C shows a data frame sent when the transmitting node wants to change the channel sampling period of the receiving node.

In FIG. 3C, the data frame includes a preloads frame, data, and a request sampling time (RSP) of 2 bytes. Here, the request sampling time is added to the end of the data frame, and this request sampling time is transmitted only once at first when the transmitting node wants to change the initial channel sampling time of the receiving node (ie, the destination node). The initial channel sampling time is determined by the network manager according to the network environment.

FIG. 3D shows an ACK frame used to ensure data transmission reliability, i.e., used to reply that the receiving node received data well from the transmitting node.

In FIG. 3D, the ACK frame includes a preamble of 4 bytes, a delimiter of 1 byte, an Ack of 4 bytes, and an address of 4 bytes. Here, Ack indicates that the frame is an ACK frame, and the address indicates its own address (that is, the address of the receiving node) that transmits the ACK frame.

Next, a data transmission process of a transmitting node according to the present invention will be described in detail with reference to FIGS. 4 and 5.

4 and 5 are exemplary diagrams for illustrating a data transmission process of a transmitting node and a data receiving process of a receiving node according to the present invention.

First, the data transmission process of the transmitting node according to the present invention will be described.

When data is sensed at the transmitting node, the transmitting node performs carrier sensing for a predetermined time to prevent data transmission collision.

Then, if channel activity by another node is not detected as a result of performing the carrier sensing, the transmitting node transmits the sensed data through relaying of another node in a multi-hop manner to a sink node on a network. Perform the process.

That is, the transmitting node has a preload message for a longer time than the channel sampling period of the receiving node for data communication with the receiving node (node corresponding to the destination of the sensed data). The included preloads frame is transmitted over the network.

Thereafter, the transmitting node transmits the data (the sensed data) on a data frame and transmits the data on the network following the preload frame transmission.

In particular, when the frequency of data sensed by the transmitting node, that is, data that the transmitting node should transmit on the network changes (occurs burst data), the transmitting node assigns a request sampling time (RSP) to the data frame. Insert it and send the data frame containing the data over the network. Here, the request sampling time RSP inserted into the data frame is calculated by the transmitting node using Equation 2 below.

In Equation 2, "T _P ^* " denotes an optimal channel sampling period (ie, a request sampling time (RSP)), and "P _sample " denotes power consumed when a node performs channel sampling. a power consuming (power), in the "P _sleep" is a node in sleep mode, "t _spl" is the channel sampling average execution time, "P _tx" is the power that the node is consumed for data transmission, "r _data Each represents a data rate occurring at the node.

Of course, in the present invention, when the transmitting node does not want to change the channel sampling time with respect to the receiving node, if the preload frame and the data are loaded on the data frame and transmitted to the receiving node without inserting the request sampling time (RSP) into the data frame. do.

After transmitting the data frame, the transmitting node waits for an ACK frame to be answered from the receiving node corresponding to the corresponding destination. At this time, if the ACK frame does not respond within a predetermined time limit, the transmitting node retransmits the data frame on the network.

The transmitting node transmits the data frame, records the address of the corresponding receiving node to receive the data frame in its preload table as shown in Table 1 below, and preload time of the preload table. The request sampling time (RSP) inserted into the data frame is recorded in the preloads period field. Here, the preload time means a time used for transmitting the preload frame as described above.

On the other hand, when a data frame in which a request sampling time (RSP) is inserted is received in the receiving node, the receiving node transmits the data frame to its own channel sampling table as shown in Table 2 below. In addition to recording an address of a transmitting node, a request sampling time (RSP) inserted into the data frame is recorded in a channel sampling period field of a channel sampling table. The operation of such a reception node will be described in more detail below.

In the present invention, all nodes, that is, the transmitting node and the receiving node each have a preload table as shown in [Table 1] and a channel sampling table as shown in [Table 2]. In each of the preload table and the channel sampling table, the value of a timer set to a predetermined value from the time when information (preferably the request sampling time (RSP)) is recorded in a specific field is directed toward "0". It is set to be driven.

In the present invention, the preload table and the channel sampling table are provided at each node to record a request sampling time (RSP) and to drive a timer to adjust the preloads period and the channel sampling period. Therefore, by changing the duty cycle of the node, it is possible to ensure low power implementation and fast data transmission of the node.

Preferably, in the present invention, in order to reduce node energy consumption in a wireless sensor network environment where data transmission / reception frequency is low, the preload time and the channel sampling time are kept long so that the duty cycle of the node is lowered. Low duty cycle implementation].

That is, in the present invention, the transmitting node prior to transmitting data to the receiving node (preferably before transmitting the preload frame immediately before transmitting the second data frame) in the preload table of the destination address corresponding to the receiving node. Inquire about whether or not exists.

If a destination address corresponding to a destination address query result of the preload table exists, the transmitting node receives a preload frame according to a time recorded in a preload time field matched with the destination address of its preload table. Preferably over a network.

On the other hand, if a destination address does not exist as a result of the destination address inquiry of the preload table, the transmitting node transmits a preload frame to a receiving node (preferably on a network) at a preset initial preload time.

Also, before transmitting data to the receiving node, the transmitting node also inquires a timer matched to a destination address corresponding to the receiving node of its preload table, and the value of the timer as a result of the timer inquiry of the preload table. If not "0", the transmitting node transmits a preload frame to a receiving node (preferably over a network) in accordance with the time recorded in the corresponding preload time field, and as a result of the timer inquiry of the preload table, If the value is "0", the transmitting node transmits a preload frame to a receiving node (preferably on a network) in accordance with a preset initial preload time. Here, it is preferable that the transmitting node deletes a field value whose value of the timer of the preload table is "0", for example, a destination address matched with the corresponding timer, and a preload time on the table, which efficiently manages the limited resources of the node. To do this.

Next, the data receiving process of the receiving node according to the present invention will be described in detail with reference to FIGS. 4 and 5.

The receiving node wakes up at a predetermined initial channel sampling time (i.e., transitions from sleep mode to active mode) to check for channel activity by other nodes on the network through channel sampling.

If the channel activity check result is determined to be in an idle state, the receiving node continuously performs channel sampling every initial channel sampling time after returning to a sleep mode, and checks the busy state as a result of the channel activity check. When the receiving node maintains the active mode, the receiving node receives a preload frame from the corresponding transmitting node.

Thereafter, the receiving node checks whether the destination address in the preload message included in the preload frame received from the transmitting node matches its address.

If the destination node does not match its address as a result of checking whether the destination address matches in the preload message, the receiving node performs channel sampling every initial channel sampling time again after returning to the sleep mode.

On the other hand, if it matches with its own address as a result of checking whether the destination address in the preload message matches, the receiving node checks the duration in the preload message included in the preload frame received from the transmitting node and returns to the sleep mode. .

Thereafter, the receiving node receives a data frame from the transmitting node in the state of transitioning from the sleep mode to the active mode after the confirmed duration.

Thereafter, the receiving node transmits an ACK frame to the transmitting node indicating that the data frame is well received.

On the other hand, the receiving node transmits and relays the data frame received from the transmitting node to another node in a multi-hop manner. If the request sampling time (RSP) is inserted in the data frame, the receiving node is the table [ The address of the transmitting node that transmitted the data frame is recorded in its channel sampling table as shown in 2], and the request sampling time (RSP) inserted into the data frame is recorded in the channel sampling time field of the channel sampling table. At the time when the receiving node records the request sampling time RSP in the channel sampling table, the timer value corresponding to the request sampling time field is driven toward “0” from that time. Here, the value of the timer of the channel sampling table is preferably set to a predetermined value in advance.

In addition, the receiving node records a plurality of values in the channel sampling time field matched with the address of the transmitting node as a result of querying the channel sampling table in recording the address of the transmitting node and the request sampling time (RSP). If there is a request sampling time (RSP) received from the], the channel sampling time is determined as the minimum value among the plurality of request sampling times (RSP).

Also, in the receiving node, it is desirable to delete the field value of the timer of the channel sampling table "0", for example, the address of the transmitting node matched with the timer, and the channel sampling time on the table. In order to operate efficiently. Of course, the receiving node performs channel sampling every initial channel sampling time unless any information (ie, channel sampling time) is recorded in the channel sampling table.

Thereafter, the receiving node transitions from the sleep mode to the active mode every channel sampling time recorded in the channel sampling table to check whether there is channel activity by another node on the network, including the transmitting node. A process of receiving the preload frame and then the data frame from the transmitting node is performed again.

Now, the above-described effects of the present invention, that is, the matters that solve the problems of the B-MAC protocol according to the conventional method in the present invention will be described in detail.

First, the present invention reduces node energy consumption due to long preamble overhearing. This will be described with reference to FIG. 5 again.

As described above, in the wireless sensor network based on the B-MAC protocol, the node consumption energy due to the long preamble overhearing is proportional to the channel sampling time. In the present invention, a plurality of preload messages in which the transmitting node is continuous instead of the existing long preamble are used. Transmit the preload frame comprising a over the network.

That is, as shown in FIG. 5, the "receiving node 1" corresponding to the destination of data to be sent by the transmitting node is included in the preload frame from the transmitting node in the state of waking at its initial channel sampling time. After confirming the duration in the preload message, the device transitions to the sleep mode instead of the active mode during the duration, and since the transition time is changed to the active mode only to receive the data frame, the energy consumption of the active mode can be prevented. .

As shown in FIG. 5, "receive node 2" which does not correspond to a destination of data to be transmitted by the transmitting node is included in a preload frame from the transmitting node in the state of waking at its initial channel sampling time. Determining the destination address in the preload message and determining that it is not the data coming to the user, transitioning to the slim mode, and then remaining in the sleep mode without receiving a subsequent preload frame, thereby consuming energy due to receiving the preload frame. Can be prevented.

Second, in order to reduce node energy consumption, a low duty cycle implementation of a node is required. In this case, a data transmission may be delayed due to a long sleep time of a transmitting node.

In order to reduce node energy consumption in a wireless sensor network environment with low data transmission / reception frequency, an ultra low duty cycle, preferably, the duty cycle value of Equation 1 is less than 0.1%. Operate Rage. This ultra low duty cycle results in a very large channel sampling time, which causes a very large transmission delay in transmitting and relaying data in a multi-hop manner in a wireless sensor network.

In order to solve this problem, the present invention transmits the preload time and the channel sampling time of all nodes located on the routing path from the source node (ie, the first transmitting node) to the sink node. Adjust to the optimum value according to the target data rate to ensure fast data transfer.

That is, each node has a preload table and a channel sampling table, and each node sets a request sampling time (RSP) received from another node as its own channel sampling time, so that its own preload time and other nodes located in the next hops. Also adjust the channel sampling time. Here, the request sampling time, that is, the optimal channel sampling time, to be sent to another node located in the next hop in each node is calculated using Equation 2 above.

For example, data sent by the first transmitting node is transmitted to another node in a multi-hop manner along the routing path with high delay, but all nodes located on the routing path from the other node located in the next-hop are optimal. Data relaying is performed using the channel sampling time and preload time, which allows data to be transmitted with guaranteed data transfer, especially QoS. This will be described with reference to FIG. 6.

FIG. 6 is a diagram for explaining an example of changing a channel sampling time between nodes on a routing path for solving a data transmission delay problem in the present invention.

Node 1 shown in FIG. 6 is called a source node, and nodes 2 and 3 are relay nodes located on a routing path from the node 1 to a sink node (not shown).

First, when the data sensed by the node 1 bursts and accumulates in an internal buffer, the node 1 calculates an optimal channel sampling time by using Equation 1 by identifying the corresponding data rate.

Subsequently, the node 1 senses channel activity on the network through carrier sensing, and when the channel is idle, the node 1 transmits a preload frame (here, the preload message included in the preload frame) to a preset initial preload time. The destination address within is the address of node 2], and then the calculated optimal channel sampling time is transmitted as a request sampling time (RSP) in a data frame over the network.

Accordingly, the node 2 on the network receives the data frame, and accordingly, the node 2 transmits the ACK frame corresponding to the reception of the data frame to the node 1.

Then, the node 1 recognizes that the data frame is well transmitted to the node 2 through the reception of the ACK frame, and the request sampling time (RSP) transmitted by the node in the preload time field together with the address of the node 2 in its preload table. After recording, start the timer.

Of course, when the node 2 receives the data frame from the node 1, the node 2 starts the timer after recording the received request sampling time RSP in the channel sampling time field together with the address of the node 1 in its channel sampling table.

The operation of Node 1 and Node 2 as described above is performed in the same way between Node 2 and Node 3, and Node 3 performs the same operation as other nodes on the routing path.

According to the operation of each node as described above, its preload time and channel sampling time are changed to optimal values according to the corresponding data rates. Thus, one-hop transmission from the subsequent data transmission after the initial data transmission is performed. It will take a very short time. This is a low duty cycle in the present invention it can be seen that even if each node is operating fast data transmission can be guaranteed. In addition, the remaining nodes not located on the routing path operate according to their initial preload time and initial channel sampling time.

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

1 is a diagram illustrating an embodiment of a data transmission / reception process of a known B-MAC protocol;

2 is a diagram illustrating an embodiment of a node energy consumption problem due to long preamble overhearing of a known B-MAC protocol.

3A is a structural diagram of an embodiment of a preload message according to the present invention;

3b is a structural diagram of an embodiment of a preload frame according to the present invention;

3c is a structural diagram of an embodiment of a data frame according to the present invention;

3d is a structural diagram of an embodiment of an ACK frame provided in the present invention.

4 and 5 are exemplary diagrams illustrating the data transmission process of the transmitting node and the data receiving process of the receiving node according to the present invention;

FIG. 6 is a diagram for explaining an example of changing a channel sampling time between nodes on a routing path for solving a data transmission delay problem in the present invention.

Claims (32)

An adaptive radio link connection control method of a sensor network node, Send data frames from the sending node to the receiving node, The data frame, A preload frame consisting of a predetermined number of successive preload messages; Data transmitted from the transmitting node to the receiving node; And A request sampling time for changing a channel sampling time of the receiving node; Each said preload message is A preamble including synchronization information between the transmitting node and the receiving node; A destination address representing the receiving node; And And a duration indicating a remaining time before the transmitting node transmits data. The method of claim 1, The receiving node, And responding to the transmitting node in an ACK frame in response to receiving the data frame from the transmitting node. The method of claim 2, The ACK frame, A method for adaptive radio link access control of a sensor network node comprising a preamble, an acknowledgment, and a receiving node address. The method according to any one of claims 1 to 3, Each of the transmitting node and the receiving node, A preload table and a channel sampling table, The preload table may include a first address field in which a receiving node address is recorded, a preload time field in which a first request sampling time sent by the transmitting node to the receiving node is recorded, the receiving node address, and the first request sampling time. A first timer field in which a timer value for deletion is recorded; The channel sampling table includes a second address field in which a transmitting node address is recorded, a channel sampling time field in which a second request sampling time received by the receiving node from the transmitting node is recorded, the transmitting node address, and the second request sampling time. And a second timer field in which a timer value for deletion is recorded. An adaptive radio link connection control method of a sensor network node, The data transmission process of the transmitting node, A preload frame transmission step of transmitting a preload frame including a predetermined number of preload messages consecutively over a network as channel activity by another node is not detected; A data frame transmission step of transmitting the data sensed by the self in the data frame and transmitting the data onto the network after completion of the preload frame transmission; And Completing the data transmission according to receiving the ACK frame from the corresponding node within a predetermined time limit after transmitting the data frame. Adaptive wireless link connection control method of a sensor network node comprising a. The method of claim 5, wherein The data frame transmission step, And transmitting a corresponding data frame onto the network by inserting a request sampling time into the data frame as the frequency of the sensed data changes. The method of claim 6, The request sampling time is, Adaptive wireless link connection control method of a sensor network node, characterized in that using the following equation (2). [Equation 2]

Here, "T _P ^* " is the request sampling time, "P _sample " is the power consumed by the node when performing channel sampling, and "P _sleep " is the power consumed by the node in the sleep mode, and "t _spl "Is the channel sampling average execution time," P _tx "is the power consumed by the node during data transmission, and" r _data "is the data rate occurring at the node. The method of claim 6, Recording a reception node address corresponding to a destination of the data frame and a request sampling time inserted into the data frame in its preload table Adaptive wireless link access control method of a sensor network node further comprising. The method of claim 8, Setting a value of a timer set to a predetermined value to be driven toward “0” from the time when the receiving node address and the request sampling time are recorded in the preload table Adaptive wireless link access control method of a sensor network node further comprising. The method according to claim 8 or 9, Querying whether there is a receiving node address corresponding to a corresponding destination in the preload table before transmitting a next preload frame; And As a result of the preload table query, if a corresponding receiving node address exists, the next preload frame is transmitted on the network according to a request sampling time matched to the corresponding receiving node address of the preload table, and the corresponding reception is performed. If the node address does not exist, transmitting the next preload frame onto the network according to a preset request sampling time; Adaptive wireless link access control method of a sensor network node further comprising. The method of claim 9, Deleting a reception node address and a request sampling time matched to a field having a timer value of "0" in the preload table. Adaptive wireless link access control method of a sensor network node further comprising. To a transmitting node with a processor, Transmitting a preload frame including a predetermined number of preload messages consecutively on the network as channel activity by another node is not detected; A function of inserting a request sampling time into a data frame and transmitting it on the network as the frequency of data sensed by the user changes; And A function of completing the data transmission after receiving the ACK frame from the corresponding node within a predetermined time limit after transmitting the data frame. A computer-readable recording medium having recorded thereon a program for realizing this. The method of claim 12, A function of recording a reception node address corresponding to a destination of the data frame and a request sampling time inserted into the data frame in its preload table; And A function of setting the timer value set to a predetermined value to be driven toward “0” from the time when the receiving node address and the request sampling time are recorded in the preload table A computer-readable recording medium that records a program for further realization. The method of claim 13, A function of querying whether a reception node address corresponding to a corresponding destination exists in the preload table before transmitting a next preload frame; And As a result of the preload table query, if a corresponding receiving node address exists, the next preload frame is transmitted on the network according to a request sampling time matched to the corresponding receiving node address of the preload table, and the corresponding reception is performed. If the node address does not exist, transmitting the next preload frame onto the network according to a preset request sampling time; A computer-readable recording medium that records a program for further realization. The method according to claim 13 or 14, A function of deleting a reception node address and a request sampling time matched to a field having a timer value of "0" in the preload table. A computer-readable recording medium that records a program for further realization. An adaptive radio link connection control method of a sensor network node, The data receiving process of the receiving node Transitioning from the sleep mode to the active mode at a preset channel sampling time to check whether there is channel activity by another node; Receiving a preload frame from a corresponding transmitting node as determined to be busy by the channel activity check result; Checking whether a destination address in the preload message included in the received preload frame matches its address; Checking a duration in a preload message included in the preload frame and returning to a sleep mode according to the address check result according to its address; And Transitioning from a sleep mode to an active mode after receiving the confirmed duration and receiving a data frame from the transmitting node Adaptive wireless link connection control method of a sensor network node comprising a. The method of claim 16, Transmitting an ACK frame including its address to the transmitting node after the data frame is received; Adaptive wireless link access control method of a sensor network node further comprising. The method of claim 16, A channel sampling table recording step of recording the address of the transmitting node and the request sampling time in its channel sampling table as the request sampling time is inserted into the data frame Adaptive wireless link access control method of a sensor network node further comprising. The method of claim 18, The channel sampling table recording step, And a plurality of channel sampling times matching the address of the transmitting node are present in the channel sampling table, so that the channel sampling time having the minimum value among the plurality of request sampling times is recorded in the channel sampling table. Adaptive wireless link access control method. The method of claim 18, Setting a value of a timer set to a predetermined value in advance toward "0" from the time when the address of the transmitting node and the request sampling time are recorded in the channel sampling table; Adaptive wireless link access control method of a sensor network node further comprising. The method of claim 20, Deleting a transmission node address and a request sampling time matched to a field having a timer value of "0" in the channel sampling table. Adaptive wireless link access control method of a sensor network node further comprising. The method according to any one of claims 18 to 21, Transitioning from the sleep mode to the active mode at each request sampling time recorded in the channel sampling table, checking whether there is channel activity by another node including the transmitting node, and receiving a next preload frame from the transmitting node. Adaptive wireless link access control method of a sensor network node further comprising. To a receiving node with a processor, A function of checking whether there is channel activity by another node by changing from a sleep mode to an active mode at a preset channel sampling time; Receiving a preload frame from a corresponding transmission node according to the busy state as a result of the channel activity check; Checking whether a destination address in a preload message included in the received preload frame matches its own address; A function of checking a duration in a preload message included in the preload frame and returning to a sleep mode according to the address check result according to its own address; And A function of receiving a data frame from the transmitting node by transitioning from a sleep mode to an active mode after the confirmed duration has passed A computer-readable recording medium having recorded thereon a program for realizing this. The method of claim 23, Transmitting an ACK frame including its own address to the transmitting node after completing the data frame reception; And Channel sampling table recording function for recording the address of the transmitting node and the request sampling time in its channel sampling table as the requested sampling time is inserted into the data frame. A computer-readable recording medium that records a program for further realization. The method of claim 24, A function of setting a value of a timer set to a predetermined value in advance toward "0" from the time when the address of the transmitting node and the request sampling time are recorded in the channel sampling table; And A function of deleting a transmission node address and a request sampling time matched to a field having a timer value of "0" in the channel sampling table. A computer-readable recording medium that records a program for further realization. The method of claim 24 or 25, Transition from sleep mode to active mode for each request sampling time recorded in the channel sampling table to check whether there is channel activity by other nodes including the transmitting node and receive the next preload frame from the transmitting node. A computer-readable recording medium that records a program for further realization. An adaptive radio link connection control method of a sensor network node, The process of changing the channel sampling time between nodes on the routing path is Calculating, by the first node, the requested sampling time based on the data rate as the data sensed by the first node bursts; Sending, by the first node, a preload frame to a second node on a routing path during a preset preload time as channel activity by another node on the network is not detected; After the first node completes the transmission of the preload frame, loading the calculated request sampling time and corresponding sensing data in a data frame and transmitting the data to the second node; And Changing its channel sampling time to a request sampling time inserted in the data frame as the second node receives the data frame from the first node; Adaptive wireless link connection control method of a sensor network node comprising a. The method of claim 27, Changing the preload time to a request sampling time sent to the second node as the first node receives an ACK frame from the second node; Adaptive wireless link access control method of a sensor network node further comprising. The method of claim 28, Sending, by the first node, a next preload frame to the second node at the changed preload time, Wherein the first node sets the preload time relatively longer than the channel sampling time of the second node and transmits a next preload frame to the second node. Connection control method. Sensor network system, Calculating, by the first node, the requested sampling time based on the data rate as the data sensed by the first node bursts; Sending, by the first node, a preload frame to a second node on a routing path during a preset preload time as channel activity by another node on the network is not detected; A function of the first node to transfer the calculated request sampling time and the corresponding sensing data to the second node after the completion of the preload frame transmission; And Changing its channel sampling time to a request sampling time inserted in the data frame as the second node receives the data frame from the first node; A computer-readable recording medium having recorded thereon a program for realizing this. The method of claim 30, Changing the preload time to a request sampling time sent to the second node as the first node receives an ACK frame from the second node; A computer-readable recording medium that records a program for further realization. The method of claim 31, wherein Transmitting the next preload frame to the second node by setting the changed preload time relatively longer than the request sampling time sent to the second node. A computer-readable recording medium that records a program for further realization.

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