WO2017209497A1 - Sensing data processing device and data processing method - Google Patents

Abstract

The data processing device for a wireless sensor network, according to the present invention, comprises: a cooperation group comprising at least two sensing nodes which transmit/receive to/from each other sensing information obtained by sensing the environments in which the sensing nodes are positioned; and a base station which receives the sensing information from said at least two sensing nodes comprised in the cooperation group and reads the sensing information, wherein each of said at least two sensing nodes at least temporarily stores and transmits also the sensing information of the other sensing node, the base station receives from any one sensing node also the sensing information of the other sensing node, and the cooperation group is comprised in a quantity of at least two. The present invention can obtain high reliability of sensing results.

Description

Sensing data processing device and data processing method

The present invention relates to a sensing data processing apparatus and a data processing method. In particular, the present invention is an apparatus and method which can be preferably applied to transfer sensing data to buoy in a rapidly changing communication environment. However, the present invention is not limited to the aquatic environment and can be applied to environmental fields similar to underwater.

The present invention also relates to a data processing apparatus and a data processing method of a wireless sensor network. More specifically, the present invention relates to a data processing apparatus and a data processing method of a wireless sensor network, which can be applied in a poor communication environment, an indoor environment, for example, a factory, which is less reliable in a communication channel. However, it is not limited to such a technical field.

 Underwater acoustic communication (UAC) has a variety of applications. For example, it can be used for monitoring the underwater environment, military / marine observation, underwater navigation, radioactive spill monitoring, and underwater resource exploration.

A wireless sensor network is generally used for the underwater acoustic communication. Its action is generally that the information sensed by these sensors is collected and transmitted to the base station of the water phase, for example buoy, via the underwater acoustic communication.

The underwater acoustics communication is time dependent. This is due to changes in spatial location due to temperature, channel geometry, surface roughness, and currents in the water. Due to these constraints, acoustic waves, mainly with low damping characteristics, are used as carriers for underwater communication.

However, hydroacoustic communication cannot obtain accurate channel state information (CSI) at the transmitter and receiver because of the limited bandwidth and time dependent response. In addition, multipath delays due to reflections in the water surface and the ground spread inter-symbol interference and frequency-selective fading. This degrades the performance of underwater acoustic communication.

Non-Patent Document 1 has been proposed as one way to overcome these problems. Orthogonal Coded Frequency Division Multiplexing (COFDM) has been applied to this document, which employs a low density parity check code (LDPC).

However, this method has a problem in that performance is degraded by random fading. In addition, the point-to-point system employed in this approach is further degraded due to the long-term deep faing, Doppler diffusion, and the presence of shadow zones. As a result, if the communication is not performed, the output power is increased or repeatedly transmitted to make up for the problem, thereby increasing the power consumption and reducing the service life of the system.

The present invention is proposed to solve the above problems, and proposes a sensing data processing apparatus and a data processing method for preventing performance degradation due to random fading.

The present invention proposes a sensing data processing apparatus and a data processing method for improving various problems caused by a point to point system.

The present invention proposes a sensing data processing apparatus and a data processing method for improving the problem of reducing the life of a system by increasing power consumption due to repetitive transmission.

However, even with the conventional method, there is still a problem that the base station does not receive the sensor detection result properly due to lack of reliability of the communication network.

In addition, due to these problems, an increase in energy consumption for retransmission and output increase still occurs.

In accordance with another aspect of the present invention, a sensing data processing apparatus includes: a node network including at least two nodes for obtaining a sensing value; And a base station receiving the sensing value from the at least two nodes, wherein any node included in the node network encodes the sensing value in a first manner to another node and the base station included in the node network. Broadcast as transmission information, and the other node encodes the transmission information in a second manner to relay to the base station. According to this, power consumption can be reduced.

In the apparatus, any node is all nodes included in the node network, and the first scheme and the second scheme are different. This maximizes power savings.

According to the present invention, there is provided a sensing data processing method comprising: sensing a node by environmental information; Which node encodes the sensed information in a first manner and broadcasts the information as transmission information; And another node receiving the transmission information encodes the information selected from the accumulated information accumulating two or more pieces of the transmission information in a second manner and relays the information to the base station as relay information. According to this, the power consumption is reduced.

In this method, any node is any node included in the node network. This can maximize the power savings.

In the method, the transmission information and the relay information are the same size. According to this, the utilization of radio resources can be improved.

In the method, the other node encodes the transmission information in a second manner as it is encoded in the first manner. This increases coding efficiency and reduces power consumption.

In the method, the first scheme is a low density parity check code orthogonal coding frequency division multiplexing (LPDC COFDM), and the second scheme is a code matrix of a low density generator matrix (LDGM). According to this, coding efficiency can be obtained to the maximum.

According to an aspect of the present invention, there is provided a data processing apparatus of a wireless sensor network, including: a cooperative group including at least two sensing nodes configured to transmit and receive sensing information of sensing an environment where a user is placed; And a base station that receives the sensing information from the at least two sensing nodes included in the cooperative group, and reads the sensing information, wherein each of the at least two sensing nodes includes at least temporary sensing information of another sensing node. The base station receives the sensed information of another sensing node from one sensing node, and includes at least two cooperative groups. By the cooperation between the sensor nodes as described above, there is an advantage that the reliability of information transmission is increased and power consumption is reduced.

In the apparatus, the at least two sensing nodes included in the cooperative group may be geographically adjacent to each other. According to this, it is possible to build a system with lower power.

In the apparatus, at least one of the at least two sensing nodes may at least temporarily store all the sensing information of the other sensing nodes of the output group in which they are included. Since all sensors can transmit the sensing information of all other sensors, the reliability of information transmission and the effect of low power have the advantage of being maximized.

In the apparatus, at least one of the at least two sensing nodes may transmit all the sensing information of the other sensing nodes of the output group including the same to the base station. According to this, there is an advantage that the reliability of information transmission and the effect of low power are maximized.

A data processing method of a wireless sensor network according to the present invention includes a grouping step of grouping a plurality of sensing nodes into at least two cooperative groups; An intra-group sensing information exchange step in which the at least two sensing nodes exchange sensing information sensed by at least two sensing nodes included in at least one cooperative group among the at least two cooperative groups; Transmitting sensing information of the at least two sensing nodes to a base station; And a sensing information reading step of reading the sensing information at the base station. According to this, reliability of data transmission can be improved and power consumption can be reduced even in a poor communication environment.

In the method, each of the at least two sensing nodes transmits their own sensing information and the sensing information of another sensing node together to the base station. According to this, communication reliability can be increased.

In the method, each of the at least two sensing nodes exchanges sensing information with all other sensing nodes included in the cooperative group in which they are included, and the sensing information of each of the other sensing nodes exchanged. The sensing information may be transmitted to the base station. The reliability of information transmission is maximized.

In the method, the sensing information includes at least normal and abnormal, and is provided as a value for discontinuously distinguishing the degree of physical quantity. According to this, it is possible to improve the accuracy of the recovery of the information transmission.

In the method, in the sensing information reading step, the received sensing information includes at least two pieces of information about the same sensing node, and the sensing information is read by a majority vote method. This has the advantage that the error probability of the information is significantly reduced.

According to the present invention, it is possible to obtain a high coding gain, and to reliably acquire information of a poor environment such as underwater, for a long time with low power consumption.

According to the present invention, it is possible to accurately monitor the environment of the region of interest using a wireless sensor network.

According to the present invention, the base station can receive an accurate detection result with a low error rate.

According to the present invention, an effect of reducing energy consumption can be expected even in a poor wireless communication environment.

According to the present invention, it is possible to determine the exact state of the sensing environment.

BRIEF DESCRIPTION OF THE DRAWINGS The figure explaining the structure of the underwater sensing data processing apparatus.

2 is a flowchart of a method for processing underwater sensing data.

3 is a graph showing information transmission with time and each node as its respective axis.

4 shows that information sensed at a node is coded.

5 is a graph showing a comparison of the performance of the examples.

Figure 6 is a graph comparing the number of nodes and power consumption by comparing the prior art and the embodiment.

7 is a diagram schematically illustrating a data processing apparatus of a wireless sensor network according to an embodiment.

8 is a diagram illustrating a configuration diagram of a sensing node.

9 is a diagram illustrating a configuration diagram of a base station.

10 is a flowchart for explaining a data processing method of a wireless sensor network.

11 illustrates a grouping message.

12 illustrates a data packet according to an embodiment.

13 illustrates a cooperative packet according to an embodiment.

Fig. 14 is a data read table according to the majority vote.

15 is a graph showing the results of performing an example simulation.

Hereinafter, with reference to the drawings will be described in detail a specific embodiment of the present invention. However, the spirit of the present invention is not limited to the following embodiments, and those skilled in the art who understand the spirit of the present invention can easily add, change, delete, or add other components that fall within the scope of the same idea. It may be suggested that the present invention be included within the scope of the present invention.

1 is a diagram illustrating a configuration of an underwater sensing data processing apparatus according to an embodiment.

Referring to FIG. 1, an underwater sensing data processing apparatus includes at least two nodes 1 having at least a sensing mechanism, and a buoy 2 provided near a water surface to receive information from the node 1. do. The node and buoy communicate data wirelessly with each other. The sensing device may measure various physical / chemical amounts, such as water temperature, flow rate, and composition. The at least two nodes may be a node network as a whole. The buoy can be used to specify the underwater environment, and may be called a base station in other cases.

At least one of the nodes 1 (eg, the first node) transfers transmission information including the measured at least sensing value to another node (eg, all nodes except the first node, and buoy). Encode and transmit in the first manner. Preferably the transmission may be provided by broadcast. In other words, the transmission information can be transmitted to all components included in the data processing apparatus. Therefore, all nodes 1 and buoy 2 except the transmitting node (for example, the first node) can receive the transmission information.

The other node 1 (e.g., all nodes except the first node) receiving the transmission information encodes the buoy () by directly encoding in the second manner without decoding the transmission information coded in the first manner. 2) can be sent. Preferably the transmission may be referred to as a relay. In other words, this is because the transmission information is relayed from the node (for example, the first node) that transmits the transmission information to the buoy (2). The buoy 2 receiving the transmission information may recover the transmission information through iterative decoding.

Every node included in the at least two nodes 1 may be the first node to broadcast transmission information including a sensing value to another node in the transmission process.

According to the apparatus described above, the transmission information lost in the broadcast can also be transmitted to buoy (2). This may work more preferably with a larger number of nodes. Through this cooperative networking, the reliability of information transmission by the transmission is increased, and thus, waste of energy can be reduced by preventing power equipment for redundant transmission in case of transmission failure.

The operation and operation of the underwater sensing data processing device can be understood in more detail by the underwater sensing data processing method presented below.

2 is a flowchart illustrating a method of processing underwater sensing data according to an embodiment.

In FIG. 2, a sensor network including U nodes and a buoy is taken as an example. For simplicity of explanation, only two nodes are presented, but of course, an appropriate number of nodes may be included.

Referring to FIG. 2, a node (eg, a first node) first performs a sensing operation (S1). The sensed information is first encoded in a first manner (S2). In the encoding of the first scheme, LPDC COFDM (Low Density Parity Check Code Orthogonal Coded Frequency Division Multiplexing) may be applied, and may be provided as Nbit amount of transmission information.

The encoded transmission information is first transmitted to another node (for example, all nodes except the first node) and buoy (S3). Accordingly, the first transmission may be referred to as broadcast, and the other node and buoy may receive the transmission information. In this case, even in the case of transmission failure, there may be no retransmission process, so the other node and the buoy may not receive some or all of the transmission information. However, the amount that cannot be transmitted may be adjusted in advance by adjusting the transmission output.

The sensing S1, the first encoding S2, and the first transmission S3 may be performed by all nodes. Therefore, even if transmission information transmitted from one node is not transmitted to another node, it may be transmitted to another node. Broadcasting between the nodes may be performed in time division multiple access (TDMA). Therefore, when one node is broadcasting, other nodes can be made to wait.

The transmission information transmitted in the first transmission S3 is not decoded by the other node. In other words, it is stored as binary information as it is received inside the other node.

When broadcast is terminated at all nodes, the transmission information will be accumulated at the node. The accumulated transmission information is called accumulation information for convenience of description. The accumulation information may also include information of the node itself in which the accumulation information is recorded. Thereafter, the accumulation information at the node is second encoded in a second manner (S4). In the second scheme, a code matrix of a low density generator matrix (LDGM) may be used. In the second encoding S4, all of the accumulated information is not encoded, and a part of the accumulated information is selectively encoded in the second manner. Information encoded in the second manner is second transmitted to the buoy (S5). This step may be referred to as a relay, and the information transmitted to the buoy may be referred to as relay information.

The second transmission may be performed in a time division multiple access scheme (TDMA). Therefore, when one node is relaying, other nodes can be made to wait.

The relay information may randomly include the transmission information from any node among the accumulation information. Therefore, even if lost in any of the first transmission (S3) step may be decoded by a plurality of the relay information.

The information transmitted after the second encoding S4 may have a size of Nbit. Then, it may be provided in the same amount as the first transmission (S3). It can be easily understood that this is because all of the accumulated information is not encoded but part thereof is selected. As a result, the time required for the first transmission and the time required for the second transmission may be provided in the same manner as Ts. That is, the transmission information and the relay information may be provided in the same amount. Of course, depending on the embodiment, the size of the relay information may be adjusted, which is a matter of selection.

If the first scheme and the second scheme are further described, the information transmitted in the second scheme may be referred to as a network code. The information transmitted in the first scheme may configure a system symbol for the network code. Similarly, the information transmitted in the second scheme may be a parity symbol.

After passing through the broadcast and the relay, a code rate of the received information received by the buoy may be given as a product of the code rate of the first scheme and the code rate of the second scheme. Therefore, the relay information may include more information.

The buoy may perform decoding using the relay information and the transmission information. The decoding may be performed by iterative decoding using an internal LDGM decoder and an external LDPC decoder.

The first transmission S3 and the second transmission S5 will be described in more detail.

3 is a graph with time and each node as its respective axis.

Referring to FIG. 3, in a time division multiple access scheme, broadcast and relay are performed.

In detail, the first transmission is a broadcast phase, in which node 1 broadcasts the transmission information for Ts time, and then node 2 broadcasts the transmission information of Nbit size for Ts time, respectively. The broadcasting step continues while all nodes (U) broadcast the transmission information. If all nodes transmit the transmission information, it will take time of UTs.

Thereafter, a relay phase is performed with the second transmission. Specifically, the relay information, which is arbitrarily selected from the accumulated information and has a size of Nbit, relays to a buoy at any node (starting at node 1 in the figure) during the Ts time. In the relaying step, the number of relaying nodes and the size of relaying information are the same as the first transmission. Thus, the relaying step continues while all nodes (U) relay the relay information. If all nodes transmit the relay information, it will take time of UTs.

The time spent as a whole in the broadcasting step and the relay step may be calculated as 2UTs.

The first coding S2 and the second coding S4 will be described in more detail.

4 is a diagram showing that information sensed by a node is coded. It should be noted that a broadcasting step and a relay step are expressed together.

Referring to FIG. 4, a circle means a bit node and a rectangle means a check node. The bit node indicates the transmission information received from the buoy in the broadcasting step S3 and the relay information received by the buoy in the relay step S5. The transmission information and the relay information may not receive all information due to a communication environment such as attenuation.

In detail, the transmission information including at least the sensed information is encoded in a first manner into N bit nodes at node 1 (for example, node 1). The other node that receives the transmission information (for example, another node except for Node 1) selects among the NU (sum of U nodes and N bit nodes) bit nodes in a random manner and selects a second node. Encoding can be performed with The selection of the random bit node indicates that the connection of the bit node and the check node in the relay step is randomly provided in the broadcasting step.

According to the above-mentioned underwater sensing data processing method, even if there is a problem in transmitting the transmission information directly from one node to buoy under the problems of reliability of communication environment and existence of shadow zone, the transmission information is stably transmitted through a cooperating network. Can be passed.

Due to the above characteristics, data can be processed with low power consumption, which will be described below through simulation results.

The simulation condition is that in an environment of depth of 50 meters, 12 and 18 nodes are distributed in an area of 100 meters by 100 meters at 7 meters on the bottom, buoys are located at 5 meters, and the transmission range of each node is 1000 meters. The water surface wind was 15 m / sec, the distance between the center of the area between buoys and nodes was 1000 m, the packet size was 32 bytes, and the data transfer rate was 2.5 kbps.

In the broadcasting step, the inter-sensor channel (ISC) is perfect and the performance degradation of 10 dB (for simulating the actual environment) is used as a factor for comparison, respectively.

5 is a graph showing the performance of each case.

Referring to FIG. 5, in the case of uncoded orthogonal frequency division multiplexing (uncoded OFDM) and in case of LPDC COFDM (low density parity check code orthogonal encoding frequency division multiplexing) (LDPC-COFDM), 12 nodes are randomly 10 dB. If there is performance degradation (12 Nodes Random ISC + 10dB), if 12 nodes are placed in a perfect channel environment (12 Nodes Random perfect ISC), if 18 nodes randomly suffers 10dB performance degradation (18 Nodes Random ISC) + 10dB), and 18 nodes are placed in a randomly perfect channel environment (18 Nodes Random perfect ISC).

Comparing the case where the LDPC-COFDM, which is a prior art (Non-Patent Document 1), and 18 nodes are randomly placed, a coding gain of approximately 13 dB was obtained in the case of the embodiment at 10-4 BER. The hatching gain is the same even if there is some degradation in the channel between nodes. Therefore, it can be seen that it works more robustly to external environmental changes. It can be seen that the coding gain is greater in the case of 18 than in the case of 12 nodes. Therefore, it can be seen that as the number of nodes increases, the coding gain increases. However, in terms of power consumption, increasing the number of nodes increases the useless power consumption, which is not preferable.

The above results indicate that the power consumption for underwater sensing data processing is much reduced in the case of the embodiment. However, in comparing the embodiment with LDPC-COFDM, which is a prior art (Non-Patent Document 1), the power consumption required for the overall operation of the data processing apparatus should be compared.

First, in the prior art, since each node transmits the transmission information to the buoy by the TDMA method, the energy for all nodes to transmit the transmission information is expressed by Equation 1 below.

Since the embodiment goes through the broadcasting step and the relay step in the TDMA manner, energy for all nodes to transmit transmission information is expressed by Equation 2.

In Equation 1 and Equation 2, Et is approximately 2W of energy consumed by the node to transmit transmission information and relay information, and Er is consumption of node and buoy to receive transmission information and relay information. About 0.8W as energy, Ei is about 0.2W as the energy for idle listening that the node does not send or receive, and Ednc is about as energy for decoding at the node and buoy in the prior art. 4 mW and Edc consumes approximately 10 mW for decoding at buoy in the case of an embodiment. The abbreviation coop means cooperating performed in the embodiment.

In the case of Equations 1 and 2, the number of nodes and the power consumption are represented in a graph as shown in FIG. Referring to FIG. 6, it is 1.58 dB for 12 nodes, 1.9 dB for 18 nodes, and converges to approximately 3 dB.

Referring to FIG. 5, in the case of 18 nodes, if the embodiment is compared with the prior art in 10-4BER, an encoding gain of approximately 13 dB can be obtained, and in the embodiment, the energy consumption of 1.9 dB is approximately 11 dB. You can see that you can save energy.

However, when the throughput is compared, the embodiment takes twice the time, so the throughput can be expected to be reduced by half compared with the prior art. However, the battery is used in an environment where the external power is not supplied to a deep water depth, and thus a high encoding gain can be obtained, thereby ensuring a battery life 6.5 times higher than that of the prior art.

According to the embodiment, it is possible to implement a sensing data processing apparatus and method that can be used underwater in a stable and high reliability in an environment where it is difficult to supply external power in a deep water.

7 is a diagram schematically illustrating a data processing apparatus of a wireless sensor network according to an embodiment.

Referring to FIG. 7, in the wireless sensor network applied to the embodiment, in a network environment in which sensing nodes are scattered, at least two sensing nodes 1 are grouped together in a cooperative group 2. At least two sensors in the cooperative group may transmit and receive the detection result. Eight cooperative groups 2 are shown in the figure.

All sensing nodes 1 included in the cooperative group 2 may transmit and receive information with the base station 3. The cooperative group 2 may be defined as, for example, a set of sensing nodes placed in the same room of the same floor of a building, or a set of sensing nodes adjacent to each other in a part partitioned inside the same room. have. Of course, other cases can also be fully illustrated.

The sensing node 1 included in any one of the cooperative groups 2 is not limited and determined. The sensing node 1 included in the cooperative group 2 may be changed in number or range. .

8 illustrates a configuration diagram of the sensing node, and FIG. 3 illustrates a configuration diagram of the base station.

8 and 9, the sensing node 1 may include at least a sensing unit 12 for sensing an environment, and other external components, for example, another sensing node 1 and a base station 3. A communication unit 13 for performing communication may be included. The controller 11 may further include a controller 11 that reads the detection result of the detector 12 and processes the information into information required for communication, or controls the operation of the detector 12. The memory 14 may further include various information necessary for the operation of the sensing node 1, information input from the outside, and at least temporarily storing the detection result of the sensing unit 12.

The base station 3 may include a communication unit 13 for communicating with the sensing node 1. In addition, the control unit 11 for controlling the overall operation of the base station 3, and a memory 14 that stores information input from the outside, and various information necessary for the operation of the base station 3 may be further included. In addition, a user interface, an input / output device, and the like may also be provided as various additional components depending on the use state.

7 to 9, the operation of the data processing apparatus of the wireless sensor network will be described. The base station 3 may transmit information to the sensing node 1 to instruct at least two sensing nodes 2 to form one cooperative group 2. The eight cooperative groups 2 presented in FIG. 1 can be considered as an example. The process of forming the cooperative group 2 may be newly performed whenever the sensing node 1 performs sensing, but may also be performed when the layout of the factory is changed or an emergency state occurs. Information on which sensing node 1 is included in which cooperation group 2 may be stored in the memory 14 and 33.

The sensing node 1 included in any one of the cooperative groups 2 may sense an environment in which it is placed. For example, the detector 12 may be attached to a machine of a factory to measure the temperature of the machine. If the detected temperature is within the normal range, the controller 11 may classify the detected information into caution, warning, and danger according to the degree of normality and deviation from the normal range. The sensed information may be treated as data. Of course, this is only an example, and the temperature value may be treated as data, and depending on the embodiment, the amount such as pressure, flow rate, etc. may be treated as data. However, by presenting a value for dividing the degree of physical quantity, it can be more suitably applied to the majority vote method described later. Of course, this is not limited to four cases (normal / caution / warning / danger). Each of the above cases can be thought of as any value that is not contiguous with each other.

The sensing node 1 included in any one of the cooperative groups 2 may transmit and receive the sensed information to each other through the communication unit 13. When transmission and reception of the sensing information of all the sensing nodes 1 is completed, all the sensing nodes 1 process the sensed information in the control unit 11 and transmit it to the base station 3. As a result, all the sensing nodes 1 transmit the sensing information of all the sensing nodes 1 in the cooperative group in which they are included to the base station 3. Accordingly, the base station 3 may obtain the detection information by overlapping the number of sensing nodes 1 included in the cooperative group 2.

A process in which one sensing node 1 transmits the sensing information to the other sensing node 1 may be performed at a short distance. This is because the cooperative group 2 may group the sensing nodes 1 which are geographically close together. Then, when the sensing nodes 1 included in the same cooperative group 2 transmit and receive the sensed information, accurate information can be transmitted and received without being greatly influenced by the communication environment.

When one sensing node 1 transmits the sensing information of all the sensing nodes 1 included in the cooperative group 2 to the base station 3, a relatively long distance must be transmitted. Thus, inferior communication can be performed. However, even at this time, since all the sensing nodes 1 included in the cooperative group have transmitted the information of all the sensing nodes 1, the sensed information recovered by decoding can be found relatively reliably according to the majority vote.

For example, when 7 sensing nodes 1 are placed in a cooperative group, and the sensing information of any one of them is decoded, there are 4 normals, 2 risks, and 1 warning. In this case, it can be judged as normal. In other words, three pieces of decoding information excluding normal may be determined that wrong information is received due to a problem of wireless communication, and the most normal may be determined to be correct information received without a problem of wireless communication.

10 is a flowchart illustrating a data processing method of a wireless sensor network according to an embodiment.

Referring to FIG. 10, a data processing method of a wireless sensor network according to an embodiment may include a grouping step, an exchange of sensing information within a group, a transmission of sensing information outside a group, and a sensing information determination step.

First, the grouping step is such that a plurality of sensing nodes 1 are included in any one cooperative group. The grouping step may be referred to as an organizing step of the network, since the sensing node 1 is grouped to be configured as an organization. The grouping step first begins with the base station 3 sending a grouping message to all sensing nodes 1 (S1). The grouping message may be referred to as a schedule packet, and is transmitted as information for scheduling to all sensing nodes of all cooperative groups under management of the base station.

11 is a diagram illustrating the grouping message.

Referring to FIG. 11, a 10-bit source address, a 10-bit destination address, a 2-bit timeout, 5-bit width information, and 32-bit bitmap information may be included.

The source address may include address information of a sensing node and a base station transmitting the information. For example, 3 bits may be allocated to the floor information of a building and 7 bits may be allocated to the positions of the sensing nodes of the same floor as the address information. Then, each floor can be assigned an address of 128 sensing nodes. Information related to the address may be referred to as local coordinate system (LCS) information.

The destination address may be similarly provided as LCS information as address information of a sensing node and a base station receiving the information.

The timeout can increase the number one by one when no information is transmitted from the transmission destination (the place of the source address) to the destination (the place of the destination address) for a predetermined time. The timeout is 2 bits and four transmission / reception operations can be performed. When the reception at the destination is not normally performed during four transmission / reception operations, the bitmap of the corresponding destination is set to 1, and the destination address can be changed.

The width information indicates the number of sensing nodes included in any one cooperative group. 5 bits indicate that 32 sensing nodes can be included in any one cooperative group. The width information may mean the number of sensing information (ie, the number of sensors included in any one cooperative group) that one sensing node can send together when the sensing node transmits the sensing information to a base station.

The bitmap information indicates whether a sensing node which should be included in the cooperative group is included in the cooperative group according to an instruction provided from the base station. If the bitmap information is 0, the grouping may not be yet grouped. have. When the base station transmits the grouping message to the sensing node, all information of the bitmap information may be set to zero.

The specific number provided in the grouping message is only an example.

Referring back to FIG. 10, the node receiving the grouping message stops the current operation (S2). Thereafter, the list of neighboring sensing nodes is updated (S3). In this case, the information of the neighboring sensing nodes may be performed by performing communication, receiving information from a base station, or being selected according to a plurality of modes preset in the sensing node by geographical relationship. It may be.

Thereafter, the bitmap is updated (S4). Here, updating of the bitmap may mean changing bitmap information of a place corresponding to its address to 1 from among the bitmap information included in the grouping message.

After updating the bitmap, the updated grouping message is transmitted to another sensing node included in the group (S5).

The updating of the bitmap (S4) and the transmitting of the updated bitmap (S5) may be continuously performed until the bitmap of all sensing nodes included in a cooperative group becomes 1. Meanwhile, which sensing node performs the update of the bitmap first may be selected by the base station, or may be randomly selected. Of course, it may be performed randomly or in a predetermined manner within any one cooperative group.

After the bitmaps of all the sensing nodes included in a cooperative group are updated (S6), the completed grouping message is transmitted to the base station (S7). In this case, it may be performed by changing the destination address to the value of the source address in the grouping message shown in FIG. 5.

When the base station receives the completed grouping message from all cooperative groups, the grouping step may end. The grouping step may be performed when necessary, such as an initial step.

After the grouping step, the base station may transmit the operation message to all sensing nodes, and the cooperative group receiving the operation message may perform the intra-group sensing information exchange step.

The sensing information exchange step in the group begins with the sensing node 1 receiving the operation message generating the sensing information by sensing the environment (S9). Thereafter, the sensing information is encoded and exchanged with other sensing nodes in the cooperative group as data packets (S10). In other words, it can be understood that one sensing node (sensing node A) included in the same cooperative group transfers its information to another sensing node (sensing node B). Then, it will be understood that information of one sensing node (sensing node A) is also stored in another sensing node (sensing node B). All nodes can mutually perform the above operation.

12 is a diagram illustrating a data packet according to an embodiment.

Referring to FIG. 12, a data packet includes 10 bits of LCS information for a source address for transmitting a data packet, 2 bits of sensing information for a type of sensing information, and 10 bits of data packet generation or data packet reception time information. Time of arrival (TOA information) may be included.

According to this, even if the sensing information passes through another sensing node, the sensing information can be identified and separated. As the detection information, there may have been normal, caution, warning, and danger.

Referring back to FIG. 10, an intra-group sensing information exchange step may be performed until it is determined that one sensing node stores sensing information of all sensing nodes included in a cooperative group that includes the sensing node. .

The intra-group sensing information exchange step is an exchange of information between sensing nodes of a close geographic location within a narrow spatial range, so that high reliability can be obtained and wireless communication can be performed with low power. Thus, even with a small output, all the information can be exchanged with each other sufficiently, and it is easy to establish a cooperative relationship between the sensing nodes.

If it is determined that one sensing node stores the sensing information of all the sensing nodes included in the cooperative group in which the sensing node is included (S11), the sensing node transmits the out-of-group sensing information at the corresponding sensing node. Sense information is transmitted to the base station in the form of a cooperative packet (S12). Of course, in some cases, for example, a failure of the sensor node, even if not all together, even if the cooperative packet can be transmitted, gathering all is preferable in terms of preventing the waste of resources.

13 is a diagram illustrating a cooperative packet according to an embodiment.

Referring to FIG. 13, LCS information, TOA information, and sensing information are included, which will be provided as a number multiplied by the number N of sensing nodes included in the cooperative group. The 10-bit delay time Td may mean a time spent in the intermediate node.

Referring back to FIG. 10, transmission of the cooperative packet from the sensing node to the base station may be performed by TDMA (time division multiple access) until the cooperative packet is transmitted from all the sensing nodes to the base station.

The sensing information transmission step may be performed until all of the sensing nodes transmit their cooperative packets to the base station, and then the sensing information determination step may be performed at the base station.

The base station decodes the received cooperation packet (S13).

As the decoded information, a majority rule may be applied to extract sensed information of a specific sensing node. This will be described in more detail with reference to the data read table shown in FIG.

Referring to FIG. 14, the vertical axis i represents a sensing unit of each sensing node, and the horizontal axis j represents a sensing node transmitting a cooperative packet. Referring to the result, when O is normal, C is warned, W is danger, and D is the risk, it is determined that the classification of the decoding result for the sensing unit of any one sensing node is the largest. Can present For example, you can see that the first sensing node is determined to be normal because there are three most normal nodes.

According to the sensing information determination step, even when the reliability of the wireless communication network between the sensing node and the base station is low, it is possible to accurately determine which one of the various sensing information. In other words, even in a poor environment of a wireless communication network, accurate sensing information can be found by recovering data intermittently input. This method can obtain accurate sensing information by majority vote even though wireless communication is performed between the sensing node and the base station with low output. Thus, data of the wireless sensing network can be processed even with low power.

15 is a graph showing a result of performing a simulation by applying the embodiment.

The simulation, in a room of 100 ㅧ 100㎡, scatters the machines, measures the temperature, classifies four types of sensing information such as normal / caution / warning / danger, and senses 20,000 cooperative groups with 12 nodes. This is the result of doing this for the cooperative group.

The probability of error was found to be low in the case of providing a cooperative group as a whole. In FIG. 9, COOP is an acronym of Coorporate Organize and Operate Protocol, which means that the embodiment is applied.

In addition, when the cooperative group is provided by any of an error of detection information (alarm error), an error of floor (floor no. Error), an error of a sensing node (sensor ID error), and an error of a time stamp (TOA error). You can see more excellent at For example, compared to the case where no cooperative group is provided, it can be seen that the error of the sensed information is obtained at an SNR where the probability of 10-3 dB error is as low as 20 dB.

According to the present invention, it is possible to obtain a high coding gain, and to reliably acquire information of a poor environment such as underwater, for a long time with low power consumption. In addition, it is expected that the applicability of the industry is highly expected because a simple program modification can improve the existing system.

According to the present invention, by applying the currently installed wireless sensor network as it is, it is possible to obtain excellent sensing characteristics only by changing a simple program. Therefore, it can be said that rapid industrial use is greatly expected.

Claims (9)

A cooperative group including at least two sensing nodes configured to transmit and receive sensing information that senses an environment where a user is placed; And A base station receiving the sensing information from the at least two sensing nodes included in the cooperative group and reading the sensing information; Each of the at least two sensing nodes, at least temporarily stores the sensing information of the other sensing node, and transmits, The base station also receives the sensing information of the other sensing node from one sensing node, And at least two cooperative groups. The method of claim 1, And at least two sensing nodes included in the cooperative group are geographically adjacent to each other. The method of claim 1, At least one of the at least two sensing nodes, at least temporarily storing all the sensing information of the other sensing node of the output group that includes the at least one sensing node. The method of claim 1, And at least one of the at least two sensing nodes transmits all of the sensing information of the other sensing nodes of the output group to which the output group is included. Grouping a plurality of sensing nodes into at least two cooperative groups; An intra-group sensing information exchange step in which the at least two sensing nodes exchange sensing information sensed by at least two sensing nodes included in at least one cooperative group among the at least two cooperative groups; Transmitting sensing information of the at least two sensing nodes to a base station; And And a sensing information reading step of reading the sensing information at the base station. The method of claim 5, wherein And each of the at least two sensing nodes transmits their own sensing information and the sensing information of another sensing node to the base station. The method of claim 6, The at least two sensing nodes, respectively Exchange sensing information with all other sensing nodes included in the cooperative group in which they are included, A data processing method of a wireless sensor network which transmits its own sensing information and sensing information of all the other sensing nodes exchanged to the base station. The method of claim 5, wherein The sensing information includes at least normal and abnormal, and is a value for discontinuously distinguishing the degree of physical quantity. The method of claim 8, In the sensing information reading step, the received sensing information includes at least two information about the same sensing node, And said sensing information is read by a majority vote method.

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