KR101603036B1 - Apparatus and method for routing in industrial wireless sensor network - Google Patents

Abstract

The present invention relates to routing device and method in an industrial wireless sensor network, and more particularly, to routing device and method in an industrial wireless sensor network, capable of improving a data transmission time and a delay time between terminals by performing cluster internal communication of a time division multiple access (TDMA) method and communications between cluster heads of a carrier sense multiple access (CSMA) method through a super frame.

Description

TECHNICAL FIELD [0001] The present invention relates to an apparatus and a method for routing in an industrial wireless sensor network,

[0001] The present invention relates to a routing apparatus and method in an industrial wireless sensor network, and more particularly, to a routing apparatus and method in an industrial wireless sensor network, And more particularly, to a routing apparatus and method in an industrial wireless sensor network that performs inter-node communication.

The industrial wireless sensor network is a network configured to wirelessly collect data collected from various sensors. It is not a means of communication different from the existing network, but aims at automated remote data collection. It is used for various application development of industrial field to have satisfactory stability and continuity.

The most common method of data collection in an industrial wireless sensor network is a method in which all the sensor nodes periodically transmit their observed data to the base node. This method is advantageous in that it can completely monitor the entire environment where the wireless sensor network is located, but there is a problem that all the nodes consume the energy because they sense the data while maintaining the active state and transmit the sensed result.

In order to save the energy required for such data collection, a method of dividing the wireless sensor network into a plurality of clusters is often used.

The multi - cluster industrial wireless sensor network is located adjacent to each other, and the sensed data include similar sensor nodes in one cluster, and the entire sensor network is operated in such a cluster unit.

1 is a block diagram of a typical multi-cluster based industrial wireless sensor network. A typical multi-cluster based industrial wireless sensor network is composed of a large number of sensor nodes and is grouped into a plurality of clusters. One cluster includes a plurality of sensor nodes and one cluster head (CH).

In the conventional industrial wireless sensor network, overlapping regions occur between neighboring clusters. When neighboring clusters use the same channel, inter-cluster interference occurs in the sensor nodes located in the overlapped region . Also, due to such inter-cluster interference, the transmission rate decreases and the end-to-end delay time increases.

Korean Registered Patent No. 10-1113454 (registered on Jan. 31, 2012)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for allocating different channel frequencies between adjacent cluster heads by a system manager and selecting a channel frequency different from that of adjacent clusters through a superframe , And a routing apparatus and method in an industrial wireless sensor network.

It is another object of the present invention to provide a routing apparatus and method in an industrial wireless sensor network that improves data transmission speed and end-to-end delay time by performing intra-cluster communication of a TDMA scheme and inter- cluster head communication of a CSMA scheme through a superframe .

It is still another object of the present invention to provide a method and apparatus for providing information on one cluster and neighboring clusters thereof, a first time slice portion for performing intra-cluster communication in the TDMA scheme using the allocated channel frequency, And a second time slice portion for performing communication between the cluster heads by using the superframe. The present invention also provides a routing apparatus and method in an industrial wireless sensor network that performs intra-cluster communication and inter-cluster head communication.

In order to achieve the above object, a routing method in an industrial wireless sensor network according to the present invention is a routing method in an industrial wireless sensor network, in which a cluster head transmits information on the cluster to a sensor node A preparation step of transmitting information on the head; An intra-cluster communication step in which the cluster head receives and collects data from the sensor nodes in a TDMA manner via a first time slice portion of the superframe; And a cluster head communication step in which the cluster head transmits data to the adjacent cluster head via a second time slice portion of the superframe in a CSMA manner.

In order to achieve the above object, a routing apparatus in an industrial wireless sensor network according to the present invention comprises a plurality of clusters including at least one sensor node and a cluster head for managing the at least one sensor node, The head selects the channel frequency through the superframe and transmits information on the cluster and information on the adjacent cluster to the one or more sensor nodes. The one or more sensor nodes transmit the sensing data to the superframe through a TDMA scheme The cluster head transmits data transmitted from the at least one sensor node to the adjacent cluster head through the superframe in a CSMA scheme.

The present invention has the effect of preventing inter-cluster interference by allocating different channel frequencies between adjacent cluster heads by the system management unit and selecting a different channel frequency from each cluster head through a superframe.

In addition, the routing operation of hundreds of large-scale sensor nodes and cluster heads that manage them is performed through a super frame. In this way, communication between the cluster heads and intra-cluster communication in the industrial wireless perception sensor network is performed through a super frame, thereby significantly improving the data transmission speed and the end-to-end delay time.

1 is a block diagram of a conventional wireless sensor network
2 is a block diagram of a routing apparatus in an industrial wireless sensor network according to the present invention.
FIG. 3 is a block diagram of a superframe used in each cluster according to the present invention
4 is a flowchart of a routing method using a routing apparatus in an industrial wireless sensor network according to the present invention.
5 is a state diagram of the cluster head according to the present invention
6 is a diagram showing a channel use pattern model;
7 is a graph showing the relationship between the average delay time of intra-cluster communication as the number of clusters increases as a result of simulation
8 is a graph showing the relationship between the average transmission rate (throughput) as the number of clusters increases as a result of a simulation

The present invention utilizes a superframe in the routing operation of a multi-cluster-based industrial wireless sensor network. The present invention assigns different channel frequencies between adjacent cluster heads (CHs) by a system management unit connected to a backbone network of an industrial wireless sensor network, and each cluster head selects a different channel frequency through a superframe. (CH-GN communication; Intra CH communication) of the TDMA scheme and inter-cluster head communication (CH-CH communication; Inter CH communication) of the CSMA scheme via the super frame.

2 is a configuration diagram of a routing device in an industrial wireless sensor network according to the present invention.

A routing apparatus in an industrial wireless sensor network according to the present invention includes a plurality of sensor nodes (GN) 10 for sensing data, a plurality of sensor nodes 10 (CH) 20 for managing the cluster head (CH) 20 are formed. Data received from the sensor node 10 is transmitted to the gateway (GW) 30 through communication between the cluster heads 20. A gateway (GW) 30 connects a plurality of cluster heads 20 to an industrial backbone network, receives data collected from a plurality of cluster heads 20, and transmits the collected data to an industrial backbone network. The system management unit 40 is connected to an industrial backbone network and allocates different channel frequencies to a plurality of cluster heads 20 so that inter-cluster interference does not occur.

The routing operation in an industrial wireless sensor network is performed in a time unit called a round, and the round is repeatedly performed. Each round consists of a setup step and an activation step. The setting step is a step of configuring the cluster. In the activation step, the intra-cluster communication in which the communication between the sensor nodes 10 and the cluster head 20 is performed and the inter-cluster head communication in which the communication between the cluster heads 20 is performed . In this activation step, the super frame according to the present invention is used.

The superframe represents a time cycle in which all the sensor nodes can transmit their sensing data to the sink node, which serves as a gateway. The superframe is used to transmit data to the gateway through intra- Time cycle.

The superframe according to the present invention is composed of three parts, a preparation part 100, a first time slice (TS) part 200 and a second time slice part 300, as shown in Fig. 3 . The preparation part 100 is a part for transmitting information on the cluster and information on its adjacent cluster heads. The first time slice portion 200 is a portion for performing intra-cluster communication in the TDMA scheme. The second time slice portion 300 is a portion for performing communication between cluster heads in the CSMA scheme.

The preparation part 100 broadcasts a channel frequency selection slot (S slot) for selecting a channel frequency allocated to the cluster, and transmits the control information transmitted from the system management part 40 to notify the selected channel frequency (C slot).

4 is a flowchart of a routing method using a routing apparatus in an industrial wireless sensor network according to the present invention. The routing method according to the present invention is characterized in that the cluster head transmits information on the cluster and information on the adjacent cluster heads to the one or more sensor nodes in the cluster through the preparation part 100 of the superframe, Cluster communication step (S30) in which the cluster head receives and collects data from one or more sensor nodes in the cluster in a TDMA manner through a first time slice portion (200) of the superframe, (S40) for transmitting data to the adjacent cluster head through a second time slice portion (300) of the superframe.

Wherein the preparing comprises: (S10) selecting (S10) the channel frequency allocated to the cluster by the system management unit (40) through the S slot of the superframe, and And notifying through the C slot of the frame (S20).

The system management unit 40 allocates different channel frequencies among adjacent clusters so that inter-cluster interference does not occur.

When a cluster is configured in the configuration phase of each round, all sensor nodes are aware of their cluster head. At the beginning of each superframe, the cluster heads select the channel to be used for intracluster communication from the designated channel set. That is, through the preparation part 100 of each superframe, the cluster head transmits the cluster information to the sensor nodes in its cluster and the information of the adjacent cluster heads receiving the communication channel.

Then, through the first time slice portion 200 of the super frame, the sensor nodes of the cluster transmit data to the cluster head through the channel allocated using the TDMA scheme.

The cluster head uses the second time slice portion 300 of the superframe for communication between adjacent cluster heads. In transmitting data to a sink node that serves as a gateway for connecting a sensor node and an external network in the communication between adjacent cluster heads, adjacent cluster heads transmit data using the CSMA method. A multi-hop forwarding scheme is used when adjacent cluster heads transmit data to the sink node.

5 shows a state diagram of the cluster head according to the present invention.

A cluster head that manages a single cluster switches between idle, TDMA-based, and CSMA-based states each time an interrupt message is generated, And performs communication.

6 is a diagram showing a channel use pattern model.

At the beginning of each superframe, the cluster head estimates idle periods and busy periods of available channels at time m + 1.

....(1)

....(One)

....(2)

....(2)

In the equations (1) and (2), α is a coefficient, β = max (1, m-W) is the lower boundary value of the window and W is the length of the window. Equations (1) and (2) include two elements.

Equation (1) represents an idle state (Ton) of a usable channel, which indicates that the channel is usable. Equation (2) indicates the usable channel busy state (Toff), which indicates that the channel is unusable.

The cluster head selects one of the idle channels to communicate with the sensor nodes belonging to the cluster.

Different channels are allocated to eliminate inter-cluster interference between adjacent clusters. The distance at which the interference occurs is related to the transmission range dtx of the sensor node.

When a plurality of cluster heads are allocated channel frequencies through the system management unit, they are further specified through a distance dru (equation (3)) from the cluster head to the system management unit.

.....(3)

..... (3)

dtxmax represents the maximum transmission range of the sensor node.

Idle time and busy time in a plurality of cluster heads are calculated using the Ton and Toff values calculated through the equations (1) and (2) and the distance value dru calculated through the equation (3) A cluster head with a relatively large value is preferentially assigned a channel frequency.

In the present invention, a cluster is selected according to a super frame.

That is, in the case where the sensor node data is communicated to the sink node (i.e., the gateway) by selecting the optimum direction such as the shortest distance direction, the cluster including the large-sized sensor nodes is classified into the inner cluster communication and the inter- In selecting a cluster head in which communication is performed among adjacent cluster heads, each cluster head performs a procedure according to a superframe.

In particular, as shown in FIG. 6, the cluster head is selected according to the value of Toff and Ton in the superframe. When selecting the cluster head, the cluster head is selected according to the Toff value (not the fixed value) having various values according to the transmission channel priority. That is, a cluster head having a relatively large idle value is selected. In this case, there is an effect that the end-to-end delay time is further shortened as compared with the case where the cluster head is randomly selected. Therefore, the number of cluster heads can be configured to be much smaller than the number of sensor nodes, and the performance is improved in terms of average delay time and transmission speed in a large-scale sensor node.

FIG. 7 is a graph showing the relationship of the average delay time of intra-cluster communication as the number of clusters increases as a result of a simulation. In the case of the present invention (TAR), it can be seen that as the number of clusters increases, the average delay time of intra-cluster communication decreases compared to the case of the prior art (PS).

FIG. 8 is a graph showing a relationship of an average transmission rate (throughput) as the number of clusters increases as a result of a simulation. In the case of the present invention (TAR), it can be seen that the average transmission rate is higher as the number of clusters increases than in the prior art.

10 and 11: sensor nodes 20 and 21: cluster head
30: gateway 40: system management unit

Claims (6)

Preparing a cluster head for transmitting information on the cluster and information on the adjacent cluster head to one or more sensor nodes in the cluster through a preparation part of a superframe;
An intra-cluster communication step in which the cluster head receives and collects data from the sensor nodes in a TDMA manner via a first time slice portion of the superframe; And
Wherein the cluster head transmits data to the adjacent cluster head via a second time slice portion of the superframe in a CSMA manner,
In the preparation step,
The cluster head selecting a channel frequency allocated to the cluster by a system management unit through an S slot of a preparation part of the superframe; and
And the cluster head informing the selected channel frequency through the C slot of the preparation part of the superframe.
delete The system according to claim 1, wherein the system management unit
A routing method in an industrial wireless sensor network that assigns different channel frequencies between adjacent clusters so that inter-cluster interference does not occur.
A plurality of clusters including one or more sensor nodes and a cluster head for managing the one or more sensor nodes,
The cluster head includes:
Selecting a channel frequency through a superframe and transmitting information on the cluster and information on the adjacent cluster to the one or more sensor nodes,
Wherein the at least one sensor node comprises:
Transmits sensing data to the cluster head in a TDMA manner through the superframe,
The cluster head includes:
Transmitting data transmitted from the at least one sensor node to the adjacent cluster head in a CSMA manner via the superframe,
In the superframe,
A preparation part for transmitting information on the cluster and information on adjacent clusters;
A first time slice portion for performing intra-cluster communication in a TDMA scheme; And
A second time slice portion for performing communication between cluster heads in a CSMA manner,
Wherein the preparation portion comprises:
A channel frequency selection slot for selecting a channel frequency assigned to the cluster, and
A control slot for broadcasting the selected channel frequency, and transmitting control information transmitted from the system management unit, in the industrial wireless sensor network.
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