Deterministic clustering routing method of wireless sensor network

Abstract

The invention discloses a position-based deterministic clustering routing technology for improving energy efficiency in a wireless sensor network. According to an existing routing technology based on random clusters, the number of clusters and the number of nodes in each round are distributed on the basis of probability, and according to the random algorithm, unnecessary messages are required, and the limitation of low load balancing efficiency exists. On the contrary, in the present invention, by characterizing the location of the sensing node, the optimal routing between the head node of K clusters and the sensing node is proposed for each round. Therefore, the service life of the network can be prolonged while load balancing is innovated, and the method has excellent competitiveness compared with the prior art.

Description

Technical Field

[0001] The disclosed embodiments relate to a deterministic cluster routing method for a wireless sensor network. Specifically, the disclosed embodiments relate to a location-based deterministic cluster routing technology for improving energy efficiency in a wireless sensor network, which equally divides clusters based on calculated location information of all nodes, thereby achieving an optimal communication path. Background Art

[0002] Wireless Sensor Networks (WSN) obtains target information from data transmitted by multiple nodes deployed in the sensor field. At this time, each node obtains energy supply from a battery, so the energy consumed by transmission must be minimized.

[0003] In some studies, in order to solve the above problems, cluster-based hierarchical routing technology is proposed as an energy-saving routing method. A representative example thereof is the Low Energy Adaptive Clustering Hierarchy (LEACH) protocol.

[0004] The LEACH protocol is that if the sensor nodes of each cluster transmit measurement data to the cluster head in each round, the cluster nodes will merge the received measurement data and transmit them to the base station.

[0005] At this time, in the LEACH protocol, the number of clusters corresponds to a random variable that is different in each round. In addition, the number of sensor nodes clustered in each round is also randomly determined.

[0006] Such uneven number of clusters and nodes in each round requires unnecessary messages and leads to inefficient load balancing. As a result, random cluster routing increases energy consumption.

[0007] That is, despite recent research in the field of wireless sensor networks, there is still a pressing need to eliminate the inhomogeneities caused by such random operation and a more energy efficient routing method is still needed.

[0008] [Prior art literature]

[0009] [Patent Literature]

[0010] (Patent Document 1) Korean Patent Gazette No. 10-1780144 (published on September 19, 2017) Summary of the invention

[0011] Technical issues

[0012] The disclosed embodiments are used to implement deterministic cluster routing in wireless sensor networks, provide a location-based deterministic cluster routing method for improving energy efficiency in wireless sensor networks, omit unnecessary control messages, and fix the number of clusters and the number of nodes in each round, thereby achieving a high level of load balancing.

[0013] Technical Solution

[0014] A method executed by a computing device for routing a cluster-based wireless sensor network in one embodiment includes: a step in which all nodes including a plurality of sensor nodes and a base station node broadcast to the remaining nodes except themselves to obtain the reception strength of a message received by each node; a step in which, based on the reception strength of the message and the transmission strength of the message, distance information between a transmitting node and a receiving node of the message is calculated; a step in which, based on the distance information, a plurality of reference nodes are determined among all nodes configured in a sensor field of the wireless sensor network; a step in which, based on the distances between the plurality of reference nodes and the distance information to at least one of the plurality of reference nodes, the coordinates of the remaining nodes are calculated; and a step in which the plurality of sensor nodes are respectively assigned to a preset number of clusters.

[0015] In one embodiment, the step of determining a plurality of reference nodes includes the step of respectively determining two nodes with the longest distance in the distance information as the first reference node and the second reference node.

[0016] In one embodiment, the step of determining multiple reference nodes includes: determining a node closest to the boundary of a circle having a first distance between a first reference node and a second reference node among the multiple reference nodes as a diameter and a midpoint of the first distance as a center as a third reference node.

[0017] In one embodiment, the sensor field uses a circle shape determined based on the first reference node, the second reference node, and the third reference node as a boundary.

[0018] In one embodiment, the step of determining a plurality of reference nodes includes: a step of calculating the coordinates of the third reference node based on the following [Mathematical Formula 1],

[0019] [Mathematical formula 1]

[0020]

[0021] Among them, x v and v may be the coordinates of the third reference node, 2L may be the diameter, d 0,v It may be the distance between the first reference node and the third reference node.

[0022] In one embodiment, the step of calculating the coordinates of the remaining nodes comprises the step of calculating the coordinates of the remaining nodes based on triangulation with the plurality of reference nodes.

[0023] In one embodiment, the step of calculating the coordinates of the remaining nodes includes: based on the following [Mathematical Formula 2], the step of calculating the coordinates of the remaining nodes:

[0024] [Mathematical formula 2]

[0025]

[0026] Among them, x i and i may be the coordinates of the sensor node corresponding to index i (hereinafter referred to as the i-th node), 2L may be the diameter, d 0,i can be the distance between the first reference node and the i-th node, d f,i may be the distance between the second reference node and the i-th node, d 0,v It can be the distance between the first reference node and the third reference node.

[0027] In one embodiment, the step of respectively allocating to clusters comprises: assigning new indexes to the sensor nodes based on coordinates of the sensor nodes; and allocating the plurality of sensor nodes to clusters based on the new indexes.

[0028] In one embodiment, the method further comprises: a step of specifying a time slot sequence of the sensor nodes; wherein the time slot sequence of the sensor nodes is specified based on a new index assigned to the sensor nodes.

[0029] In one embodiment, the method further comprises: the step of specifying a head node within the cluster;

[0030] The head node in each cluster is determined to be any one of the sensor nodes included in each cluster based on the following [Mathematical Formula 3] in each round.

[0031] [Mathematical formula 3]

[0032] H=(K-1)G+(R-1)%G+1

[0033] Among them, H may be the index of the node corresponding to the head node, K may be the cluster number, G may be the number of sensor nodes in the cluster, and R may be the round number.

[0034] Effects of the Invention

[0035] According to the disclosed embodiments, the locations of all nodes may be calculated from a reference node within a circular sensor field determined based on the received strength of the message.

[0036] According to the disclosed embodiment, a head node and a transmission order are determined according to an index given based on the coordinates of a sensor node, so that unnecessary control messages can be omitted.

[0037] According to the disclosed embodiment, the number of clusters and the transmission order of nodes within the clusters are fixed in each round, so that a high level of load balancing can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a traditional cluster-based routing protocol for wireless sensor networks.

[0039] Figure 2 The block diagram is used to describe a computing device for executing a deterministic cluster routing method for a wireless sensor network according to an embodiment.

[0040] Figure 3 The following is an exemplary diagram for describing the process of calculating the coordinates of all nodes for routing according to the present invention.

[0041] Figure 4 The diagram is an example of describing the clustering process for routing according to the present invention.

[0042] Figure 5 FIG. 4 is a graph for comparing the performance of a method of a wireless sensor network according to an embodiment.

[0043] Figure 6 The flowchart is used to describe a deterministic cluster routing method for a wireless sensor network according to an embodiment. DETAILED DESCRIPTION

[0044] Definition of terms

[0045] In this specification, the wireless sensor network based on deterministic clustering may refer to a network that performs optimal routing in a manner without random variables in a state where the coordinates of all nodes arranged in the sensor field are calculated.

[0046] In this specification, a plurality of reference nodes are nodes used to calculate the coordinates of all nodes, and are assumed to be located near the boundary of the sensor field.

[0047] In the present specification, a first reference node may refer to a node corresponding to a base station node. In the present specification, a second reference node may refer to a node that becomes a reference in determining a diameter of a sensor field. In the present specification, a third reference node may refer to a node that becomes a reference in determining a position of a circular sensor field.

[0048] On the other hand, the terms "first", "second" and the like are only used to distinguish various constituent elements, and the constituent elements are not limited by the terms.

[0049] In this specification, the following symbols may be defined as shown in [Table 1].

[0050]

Table 1

[0051]

[0052]

[0053] Figure 1 It is a traditional cluster-based routing protocol for wireless sensor networks.

[0054] Reference Figure 1 ,The clustering-based wireless sensor networks perform a setup phase in each round.

[0055] Specifically, the setup phase requires the node that randomly becomes the cluster head in the corresponding round to broadcast an advertisement message (ADV) in order to notify itself as the head node. Then, the setup phase requires the non-head node to transmit a join message in order to participate in one of the clusters. Finally, the setup phase requires the head node to transmit a TDMA message within each cluster in order to specify the time slot of the sensor node.

[0056] The setup phase is a step that is performed before the sensor node transmits the received information, and is a necessary step for collecting information. Therefore, if the setup phase can be omitted in a cluster-based wireless sensor network, it can become an energy-efficient protocol.

[0057] However, the setup phase is a step that is generated because the order of time slots of the head node and non-head nodes is not specified, and there is a need to remove it.

[0058] Description of Exemplary Embodiments of the Invention

[0059] Figure 2 FIG. 1 is a block diagram of a computing device 100 for describing a method for executing a deterministic cluster routing method for a wireless sensor network according to an embodiment of the present invention.

[0060] Reference Figure 2 , the computing device 100 includes a processor 110 and a memory 120 .

[0061] The processor 110 performs routing on the wireless sensor network based on deterministic clustering.

[0062] First, the processor 110 obtains the reception strength of messages that are broadcasted by all nodes including a plurality of sensor nodes and a base station node to nodes other than the node itself and received by each node.

[0063] At this time, the transmission intensity of the message broadcast by all nodes to the remaining nodes except themselves can be the same. As a specific example, the transmission intensity of the message is a preset value, which can be defined as the transmission intensity P corresponding to the transmission distance 2L. g At this time, the preferred message uses technologies such as CSMA / CA to prevent conflicts.

[0064] The message is a message in bits, and the time it takes to transmit 1 bit is E. T (l,d) Energy message.

[0065] Specifically, E T (l, d) can be defined as shown in the following [Mathematical Formula 1].

[0066] [Mathematical formula 1]

[0067]

[0068] Among them, E T (l, d) can refer to the energy consumed by the sensor node when transmitting a 1-bit message at a distance d, E e , ε f , ε m , δ can represent any real number.

[0069] Preferably, E e The in-circuit energy per bit can be 50 [nJ / bit].

[0070] Preferably, ε f As the energy attenuation coefficient in the self-space model, it can be 10[pJ / bit / m 2 ].

[0071] Preferably, ε m As the energy attenuation coefficient in the multipath model, it can be 0.0013 [pJ / bit / m 4 ].

[0072] Preferably, δ is taken as The corresponding value, which is the boundary value for switching from the free space model to the multipath model, may be approximately 87.7 [m].

[0073] On the other hand, the node receiving the message and the node transmitting the message are assumed to be symmetrical channels with each other. In other words, for the convenience of calculation, it is preferably assumed that the signal strength of the message is the same when it is transmitted in the reverse direction.

[0074] The processor 110 calculates the distance information between the transmitting node and the receiving node of the message based on the receiving strength of the message and the transmitting strength of the message.

[0075] That is, the processor 110 may calculate the distance information between the transmitting node and the receiving node of the message based on the preset message transmission strength and the obtained message reception strength.

[0076] All nodes report the reception strength of messages received from other nodes, so that the processor 110 can obtain the reception strength of messages between all nodes. The reception strength of the message is called P r .

[0077] Specifically, the processor 110 may use the reception strength of the message to calculate the distance information between the transmitting node and the receiving node of the message as shown in the following [Mathematical Formula 2].

[0078] [Mathematical formula 2]

[0079]

[0080] Among them, d i,j It can refer to the distance between the i-th node and the j-th node that sends and receives messages, P r It may refer to the reception strength of the message at the i-th node or the j-th node. On the other hand, for the convenience of description, repeated contents are not repeated.

[0081] The processor 110 may determine a plurality of reference nodes among all nodes configured in the sensor field of the wireless sensor network based on the distance information.

[0082] As multiple reference nodes, the processor 110 may determine two nodes having the longest distances in the distance information as the first reference node and the second reference node, respectively.

[0083] In other words, the processor 110 may identify the first reference node as n0, and determine the coordinates satisfying the following [Mathematical Formula 3] as the coordinates of the second reference node.

[0084] [Mathematical formula 3]

[0085]

[0086] Among them, n f When the distance between the i-th sensor node and the first reference node n0 is the largest, the corresponding distance may be referred to as d o,i , at this time, the index i is called the index of the second reference node (f).

[0087] As multiple reference nodes, the processor 110 may determine, as the third reference node, a node that is closest to a boundary of a circle having a first distance between the first reference node and the second reference node as a diameter and a midpoint of the first distance as a center.

[0088] Specifically, the processor 110 may determine the coordinates satisfying the following [Mathematical Formula 4] as the coordinates of the third reference node.

[0089]

[0090] Among them, n v It can refer to the third reference node. When the i-th sensor node is connected to the first reference node (d o,i ) and the Euclidean distance to the second reference node (d f,i ) reaches a maximum, index i can be called the index (v) of the third reference node.

[0091] Specifically, the processor 110 may calculate the coordinates of the third reference node based on the following [Formula 5].

[0092] [Formula 4]

[0093]

[0094] Among them, x v and v may be the coordinates of the third reference node, 2L may be the first distance, d 0,v It can be the distance between the first reference node and the third reference node.

[0095] On the other hand, according to [Mathematical Formula 4], in a calculation with a limited number of significant digits, there may be multiple third reference nodes. The processor 110 may first assume any one of the two values ​​as the coordinate of the third reference node, and when the coordinate calculations of the remaining nodes are inconsistent, correct them to the other one, thereby eliminating the uncertainty of the coordinate of the third reference node.

[0096] The processor 110 may define the shape of a circle determined based on the first reference node, the second reference node, and the third reference node as a boundary of the field.

[0097] The processor 110 may calculate the coordinates of the remaining nodes according to the distances between the multiple reference nodes and the distance information to at least one of the multiple reference nodes.

[0098] Specifically, the processor 110 may calculate the coordinates of the remaining nodes based on triangulation with a plurality of reference nodes.

[0099] Specifically, the processor 110 may calculate the coordinates of the remaining nodes (x i ,y i ).

[0100] [Formula 5]

[0101]

[0102] Among them, x i and i may be the coordinates of the node corresponding to index i (hereinafter referred to as the i-th node), 2L may be the first distance, d 0,i can be the distance between the first reference node and the i-th node, d f,i It can be the distance between the second reference node and the i-th node.

[0103] Among them, x i Coordinates can be marked as positive (+) or negative (-), where the exact x i The coordinates can be calculated from the distance to the third reference node according to [Formula 7].

[0104] The processor 110 may respectively allocate the plurality of sensor nodes to a preset number of clusters.

[0105] At this time, it is preferred that the number of clusters is a fixed value assigned in each round.

[0106] The processor 110 may assign a new index to the sensor node based on the coordinates of the sensor node. The processor 110 may allocate the plurality of sensor nodes to the cluster based on the new index.

[0107] The processor 110 may specify a time slot order for the sensor nodes.

[0108] The processor 110 may specify the time slot order of the sensor nodes based on the new index assigned to the sensor nodes. For example, the processor 110 may specify the time slots of the sensor nodes in sequence based on the index order or in reverse order.

[0109] The processor 110 may designate a head node within the cluster in each round.

[0110] The processor 110 may determine the head node in each cluster as any one of the sensor nodes included in each cluster based on the following [Math 6] in each round.

[0111] [Mathematical formula 6]

[0112] H=(k-1)G+(r-1)%G+1

[0113] Among them, H may be the index of the node corresponding to the head node, k may be the cluster number, G may be the number of sensor nodes in the cluster, and r may be the round number.

[0114] The memory 120 may store one or more instructions executed by the processor 110 .

[0115] The memory 120 may store various data used by the processor 110. For example, the memory 120 may include software (eg, input data or output data of a program executed by the processor 110 and / or instructions associated with the program).

[0116] on the other hand, Figure 2 It is described as being executed by a computing device, but this is only an exemplary execution entity and is not necessarily limited to this. It may also include entities such as aggregation nodes or base station nodes that can execute wireless sensor network routing.

[0117] Figure 3 The following is an exemplary diagram for describing the process of calculating the coordinates of all nodes for routing according to the present invention.

[0118] Reference Figure 3 , at the boundary of the circular sensor field, a first reference node, a second reference node and a third reference node are determined.

[0119] At this time, the diameter of the circular sensor field may be determined based on the distance (2L) between the first reference node and the second reference node, and the center of the circle may be determined based on the midpoint between the first reference node and the second reference node.

[0120] For example, Figure 3 As shown, when the first reference node is (L, 2L) and the second reference node is (L, 0), the circular sensor field may include a sensor field having a circle with a diameter of 2L and a center at (L, L) as a boundary.

[0121] At this time, the third reference node is the sensor node located closest to the boundary of the circular sensor field, and it is assumed that it is located on the boundary of the circle. Therefore, the third reference node can be calculated by the following two equations.

[0122]

[0123] at this time, is the product of the distances between the first reference node and the third reference node.

[0124] The remaining nodes can be found from the coordinates of multiple reference nodes using triangulation.

[0125] On the other hand, the x coordinates of the remaining nodes can be calculated according to the following [Formula 7].

[0126] [Formula 7]

[0127]

[0128] Among them, d * It can be calculated according to the following [Formula 8].

[0129] [Mathematical formula 8]

[0130]

[0131] Figure 4The diagram is an example of describing the clustering process for routing according to the present invention.

[0132] Reference Figure 4 , the processor 110 may evenly distribute the 100 sensor nodes included in the circular sensor field to the five clusters.

[0133] on the other hand, Figure 4 The sensor nodes are based on the following premise, that is, new indexes from 1 to 100 are assigned based on distance information. The new index implies that the closer the index number is, the denser the corresponding sensors are configured.

[0134] At this time, the processor 110 may evenly distribute the sensor nodes belonging to each cluster based on the number of preset clusters in each round. Figure 4 As shown, the processor 110 may allocate 20 sensor nodes to each cluster and evenly distribute 100 sensor nodes to 5 clusters.

[0135] The processor 110 may also specify the head node in each cluster in each round. Based on the above [Mathematical Formula 6], the processor 110 may determine the head nodes of each cluster as 1, 11, 21, 31, and 41 in one round. Similarly, in two rounds, the head nodes of each cluster may be determined in rotation as 2, 12, 22, 32, and 42.

[0136] Figure 5 FIG. 4 is a graph for comparing the performance of a method of a wireless sensor network according to an embodiment.

[0137] Figure 5 The lifetime of each routing method is shown from the perspective of the number of sensor nodes that can operate without completely consuming energy.

[0138] The lifetime of the routing method is when the total number of available sensor nodes is N and all of them are exhausted and not in operation. At this time, it can be confirmed that the routing method in this specification is significantly longer than the existing conventional LEACH method.

[0139] Figure 6 The flowchart is used to describe a deterministic cluster routing method for a wireless sensor network according to an embodiment.

[0140] Reference Figure 6 , Figure 6 The method can be Figure 1 Executed by computing device 100.

[0141] First, the computing device 100 obtains the reception strength 610 of the message broadcast by all nodes including a plurality of sensor nodes and base station nodes to the remaining nodes except themselves and received by each node.

[0142] Then, the computing device 100 calculates the distance information 620 between the transmitting node and the receiving node of the message based on the receiving strength of the message and the transmitting strength of the message.

[0143] Then, the computing device 100 determines a plurality of reference nodes 630 among all nodes configured in the sensor field of the wireless sensor network based on the distance information.

[0144] Then, the computing device 100 calculates the coordinates 640 of the remaining nodes through the distance information between the multiple reference nodes and the distance information to at least one of the multiple reference nodes.

[0145] Then, the computing device 100 allocates the multiple sensor nodes to a preset number of clusters 650 .

[0146] The above detailed description is provided to help fully understand the methods, devices and / or systems described in this specification, but it is only an example and the present invention is not limited thereto.

[0147] In describing an embodiment, if it is judged that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the embodiment, the detailed description will be omitted.

[0148] The terms used in this specification are defined as terms that are considered to be functional in the present invention, and they may vary depending on the intention or practice of the user or operator. Therefore, their definitions should be defined based on the overall content of this specification. The terms used in the detailed description are only used to describe an embodiment and shall not be restrictive.

[0149] Unless explicitly used otherwise, expressions in the singular include the meaning of the plural form.

[0150] The above detailed description of the representative embodiments of the present invention, but those skilled in the art of the present invention can understand that various modifications can be made to the above embodiments without exceeding the scope of the present invention. Therefore, the scope of the present invention is not limited to the embodiments described, but should be determined according to the following claims and the contents equivalent to the claims.

Claims

1. A deterministic cluster routing method for a wireless sensor network, the method being executed by a computing device for routing a cluster-based wireless sensor network, characterized in that: The method comprises: All nodes including a plurality of sensor nodes and base station nodes broadcast to other nodes except themselves respectively to obtain the receiving strength of the message received by each node; The step of calculating the distance information between the transmitting node and the receiving node of the message based on the receiving strength of the message and the transmitting strength of the message; Based on the distance information, a step of determining a plurality of reference nodes among all nodes configured in a sensor field of the wireless sensor network; The step of calculating the coordinates of the remaining nodes by using the distances between the plurality of reference nodes and the distance information to at least one of the plurality of reference nodes; and The step of respectively allocating the plurality of sensor nodes to a preset number of clusters.

2. The deterministic cluster routing method for wireless sensor networks according to claim 1, characterized in that: The step of determining a plurality of reference nodes comprises: The step of respectively determining two nodes with the longest distance in the distance information as the first reference node and the second reference node.

3. The deterministic cluster routing method for wireless sensor networks according to claim 1, characterized in that: The step of determining a plurality of reference nodes comprises: The step of determining a node closest to the boundary of a circle having a first distance between a first reference node and a second reference node among the plurality of reference nodes as a diameter and a midpoint of the first distance as a center as a third reference node.

4. The deterministic cluster routing method for wireless sensor networks according to claim 3, characterized in that: The sensor field has a circle shape determined based on the first reference node, the second reference node, and the third reference node as a boundary.

5. The deterministic cluster routing method for wireless sensor networks according to claim 3, characterized in that: The step of determining a plurality of reference nodes comprises: The step of calculating the coordinates of the third reference node based on the following [Mathematical Formula 1], [Mathematical formula 1] Among them, x v and v is the coordinate of the third reference node, 2L is the diameter, d 0，v is the distance between the first reference node and the third reference node.

6. The deterministic cluster routing method for wireless sensor networks according to claim 1, characterized in that: The step of calculating the coordinates of the remaining nodes comprises: The step of calculating the coordinates of the remaining nodes based on triangulation with the plurality of reference nodes.

7. The deterministic cluster routing method for wireless sensor networks according to claim 3, characterized in that: The step of calculating the coordinates of the remaining nodes comprises: Based on the following [Mathematical Formula 2], the step of calculating the coordinates of the remaining nodes is: [Mathematical formula 2] Among them, x i and i is the coordinate of the sensor node corresponding to index i, the sensor node corresponding to index i is hereinafter referred to as the i-th node, 2L is the diameter, d 0，i is the distance between the first reference node and the i-th node, d f，i is the distance between the second reference node and the i-th node, d 0，v is the distance between the first reference node and the third reference node.

8. The deterministic cluster routing method for wireless sensor networks according to claim 1, characterized in that: The step of respectively allocating to clusters comprises: The step of assigning a new index to the sensor node based on the coordinates of the sensor node; and The step of assigning the plurality of sensor nodes to clusters based on the new index.

9. The deterministic cluster routing method for wireless sensor networks according to claim 8, characterized in that: The method further comprises the step of specifying a time slot sequence of the sensor nodes, The time slot order of the sensor nodes is specified based on the new index assigned to the sensor nodes.

10. The deterministic cluster routing method for wireless sensor networks according to claim 8, characterized in that: The method further comprises: a step of specifying a head node in the cluster, The head node in each cluster is determined to be any one of the sensor nodes included in each cluster based on the following [Mathematical Formula 3] in each round. [Mathematical formula 3] H=(K-1)G+(R-1)%G+1 Among them, H is the index of the node corresponding to the head node, K is the cluster number, G is the number of sensor nodes in the cluster, and R is the round number.

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