A RSSI three-dimensional positioning method based on multiple communication radius and distance correction

Abstract

A three-dimensional RSSI positioning method based on multiple communication radii and distance correction relates to an RSSI three-dimensional positioning method. The present invention uses a five-step communication mechanism and a distance correction factor to segmentally screen anchor nodes and correct the distance estimated using the RSSI three-dimensional ranging positioning model. The method first utilizes the multiple communication radii of the unknown node to segmentally communicate with the anchor node and calculate the distance between the anchor node and the unknown node using the RSSI three-dimensional ranging positioning model. The correction factor is then introduced to correct the estimated distance. A free space loss model of node energy is then used to calculate the residual energy of the anchor node after communication. Four anchor nodes with fewer partners and higher residual energy are selected based on constraints. Finally, spatial projection technology is used to calculate the angle of the unknown node in the sensor network space. Finally, a position estimation method is used to determine the coordinates of the unknown node. This method improves node positioning accuracy, network energy loss, and positioning time, thereby increasing node positioning accuracy, reducing network energy loss, and saving positioning time.

Description

Technical Field

[0001] The present invention relates to an RSSI three-dimensional positioning method, in particular to an RSSI three-dimensional positioning method based on multiple communication radii and distance correction. Background Art

[0002] Wireless sensor networks have a wide coverage area and highly random node deployment. When a node collects data, it is almost useless without location information. Therefore, the sensor node must clearly know its own location in order to explain in detail "what event occurred at what location" to achieve positioning and tracking of external targets. Summary of the Invention

[0003] The purpose of the present invention is to provide an RSSI three-dimensional positioning method based on multiple communication radii and distance correction. The method adds multiple communication radii to optimize the node screening process, reduces the energy loss of the sensor network system, reduces the time required for positioning, and introduces a distance correction factor to correct the estimated distance, thereby improving the node positioning accuracy. Through performance analysis, the present invention improves the positioning accuracy of RSSI ranging positioning nodes.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A three-dimensional RSSI positioning method based on multiple communication radii and distance correction, the method comprising the following steps:

[0006] (1) Initialize the wireless sensor network in three-dimensional space. Sensor nodes are randomly deployed in the network, and the nodes communicate autonomously to form a network.

[0007] (2) Select the target area in the three-dimensional space to distribute the anchor nodes and unknown nodes. The attributes of each node in the area are different. All nodes are unified and their units are standardized.

[0008] (3) The location information of the anchor nodes distributed in the target area in space is known, and the anchor nodes with known coordinates are aggregated into a set;

[0009] (4) Assume that all sensor nodes have a maximum communication radius, and all unknown nodes in the space communicate with the anchor node using a five-step communication mechanism;

[0010] (5) The unknown node communicates with the anchor node in each communication radius in turn. The anchor node broadcasts its own information in the network. The unknown node receives the anchor node broadcast information and records its initial energy, coordinates, and RSSI value;

[0011] (6) In the initial stage, the unknown node broadcasts information with a communication radius of 0.2R, forming a spatial topological structure with the anchor nodes within the range. The distance between the unknown node and all anchor nodes within the communication radius of 0.2R is calculated through the ranging positioning model in the RSSI three-dimensional ranging positioning method;

[0012] (7) In order to improve the accuracy of the distance value estimated by the RSSI ranging model, a distance correction factor is introduced ; Given the coordinate information of the anchor nodes within the communication radius 0.2R, the distance correction factor is calculated based on the ratio of the actual distance between the anchor nodes to the distance estimated by the ranging model;

[0013] (8) The distance D corrected by the distance correction factor can be obtained by formula (5), as shown in formula (6):

[0014] (6);

[0015] (9) Using the energy loss model of wireless signals during node communication, namely the free space loss model

[49] , to calculate the remaining energy after node information transmission;

[0016] (10) The number of unknown nodes communicating with the anchor node is its partner number F. The partner number starts from 0 and increases by 1 for each unknown node it communicates with.

[0017] (11) According to step (10), the anchor nodes that can add partners are screened, and the anchor nodes with more residual energy are screened out in combination with the node energy loss. The number of partners of the selected anchor nodes is increased by 1;

[0018] (12) According to the five-step communication mechanism, repeat steps (6) to (11) to screen segments until four anchor nodes are selected;

[0019] (13) Construct a plane triangle in space with every three nodes of the four anchor nodes selected in step (12), and calculate the normal vectors of the constructed plane triangles respectively; then project the plane triangle formed by the three anchor nodes in space to obtain the new anchor node projection coordinates, reconstruct the plane triangle, and calculate the angle between the normal vector and the new plane triangle;

[0020] (14) Through steps (1) to (13), the angle and distance between the unknown node and the anchor node are obtained, and then the coordinates of the unknown node can be calculated by combining the position estimation method.

[0021] The advantages and effects of the present invention are:

[0022] The MD-RSSI three-dimensional positioning method of the present invention improves the problems of node positioning accuracy, network energy loss and positioning time, improves the node positioning accuracy, reduces network energy loss and saves positioning time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings.

[0025] The MD-RSSI (Multiple Communication Radius and Distance Corrections RSSI) three-dimensional positioning method uses a five-step communication mechanism and distance correction factors to segment anchor nodes and correct the distance estimated by the RSSI three-dimensional ranging positioning model.

[0026] Specifically, the unknown node first communicates with the anchor node in multiple communication radius segments and calculates the distance between the anchor node and the unknown node using the RSSI three-dimensional ranging positioning model. A correction factor is then introduced to correct the estimated distance. A free-space loss model of node energy is then used to calculate the residual energy of the anchor node after communication. Four anchor nodes with a small number of partners and high residual energy are selected based on constraints. Finally, spatial projection techniques are used to calculate the angle of the unknown node in the sensor network space. Finally, position estimation methods are used to determine the coordinates of the unknown node. The improved MD-RSSI three-dimensional positioning method improves node positioning accuracy, network energy loss, and positioning time, increasing node positioning accuracy while reducing network energy loss and saving positioning time.

[0027] Example 1

[0028] The RSSI three-dimensional positioning method with multiple communication radii and distance correction of the present invention uses a five-step communication mechanism and a distance correction factor to improve the positioning accuracy of unknown nodes, reduce network energy consumption, and save positioning time. The specific steps are as follows:

[0029] (1) Initialize the wireless sensor network in three-dimensional space. Sensor nodes are randomly deployed in the network, and the nodes communicate autonomously to form a network.

[0030] (2) Select the target area in the three-dimensional space to distribute the anchor nodes and unknown nodes. The attributes of each node in the area are different. All nodes are unified and their units are standardized.

[0031] (3) The location information of the anchor nodes distributed in the target area is known. The anchor nodes with known coordinates are aggregated into a set. Indicates that its set As shown in formula (1):

[0032] (1)

[0033] (4) Assume that the maximum communication radius of all sensor nodes is R, and all unknown nodes in the space communicate with the anchor node using a five-step communication mechanism. Assume that there are at least four anchor nodes within the communication radius R of the unknown node, and the unknown node communicates with the anchor node with a communication radius of 0.2R, 0.4R, 0.6R, 0.8R, and R respectively. There are six cases of the relationship between the distance d between the unknown node and the anchor node and the communication radius, as shown in formula (2):

[0034] (2)

[0035] (5) The unknown node communicates with the anchor node in each communication radius in turn. The anchor node broadcasts its own information in the network. The unknown node receives the anchor node broadcast information and records its initial energy, coordinates, RSSI value, etc.

[0036] (6) In the initial stage, the unknown node broadcasts information with a communication radius of 0.2R, forming a spatial topological structure with the anchor nodes within the range. The distance between the unknown node and all anchor nodes within the 0.2R communication radius is calculated through the ranging positioning model in the RSSI three-dimensional ranging positioning method, as shown in formula (3):

[0037] (3)

[0038] Among them, RSSI (d) is the RSSI value of the signal received by the anchor node when the transmission distance is d, and the unit is dBm; The sending distance is The RSSI value of the signal received by the anchor node at this time is in dBm. The standard deviation is Normal random variable, taking into account environmental factors The general value is between 3.0 and 14.1dB.

[0039] From formula 4.3, we can know that the distance between the anchor node and the unknown node is calculated as shown in formula (4):

[0040] (4)

[0041] (7) In order to improve the accuracy of the distance value estimated by the RSSI ranging model, a distance correction factor is introduced Given the coordinate information of the anchor nodes within the communication radius 0.2R, the distance correction factor can be calculated based on the ratio of the actual distance between the anchor nodes to the distance estimated by the ranging model, as shown in formula (5):

[0042] (5)

[0043] is the Euclidean distance between anchor nodes, is the distance estimated by the RSSI ranging model between anchor nodes, i is the anchor node, represents the coordinate set of the anchor node, , They are the Euclidean distance value and estimated distance value between anchor node i and any other anchor node within the communication radius, is the distance correction factor.

[0044] (8) The distance D corrected by the distance correction factor can be obtained by formula (5), as shown in formula (6):

[0045] (6)

[0046] (9) The energy loss model of wireless signals during node communication, i.e., the free space loss model

[49] , is used to calculate the remaining energy after node information transmission, as shown in formula (7):

[0047] (7)

[0048] is the remaining energy after node data propagation, is the initial energy of the node, is the node data transmission distance, is the frequency of the wireless signal.

[0049] (10) The number of unknown nodes communicating with the anchor node is its partner number , the number of partners starts from 0, and the number of partners increases by 1 each time an unknown node is communicated. The number of partners around each anchor node is limited according to the ratio of the initial energy of the anchor node, as shown in formula (8):

[0050] (8)

[0051] 、 Anchor node 、 The number of partners, 、 Anchor nodes 、 The initial energy, 、 Anchor node The distance to the unknown node.

[0052] The more initial energy an anchor node has and the shorter the communication distance, the more partners it has around it. When the number of partners around an anchor node reaches the upper limit, the anchor node will no longer add new partners.

[0053] (11) According to step (10), the anchor nodes that can add partners are screened, and the anchor nodes with more residual energy are screened out in combination with the node energy loss. The number of partners of the selected anchor nodes is increased by 1, as shown in formula (9):

[0054] (9)

[0055] (12) According to the five-step communication mechanism, repeat steps (6) to (11) for segmented screening until four anchor nodes are selected.

[0056] (13) Construct a plane triangle in space with three nodes for each of the four anchor nodes selected in step (12), and calculate the normal vectors of the constructed plane triangles. Then project the plane triangle formed by the three anchor nodes in space to obtain the new anchor node projection coordinates, reconstruct the plane triangle, and calculate the angle between the normal vector and the new plane triangle. The angle calculation is shown in formula (10):

[0057] (10)

[0058] in is the normal vector of the construction plane, 、 are two vectors of anchor nodes, is the normal vector of the new plane triangle, 、 is the vector of the new anchor node, is the angle between the two normal vectors.

[0059] (14) Through steps (1) to (13), the angle and distance between the unknown node and the anchor node can be obtained, and then the coordinates of the unknown node can be calculated by combining the position estimation method.

Claims

1. A three-dimensional RSSI positioning method based on multiple communication radius and distance correction, characterized in that: The method comprises the following specific steps: (1) Initialize the wireless sensor network in three-dimensional space. Sensor nodes are randomly deployed in the network, and the nodes communicate autonomously to form a network. (2) Select the target area for distributing anchor nodes and unknown nodes in three-dimensional space. The attributes of each node in the area are different. All nodes are unified and their units are standardized. (3) The anchor nodes distributed in the target area in space, whose location information is known, are aggregated into a set of anchor nodes with known coordinates; (4) Assume that the maximum communication radius of all sensor nodes is R, and all unknown nodes in the space communicate with the anchor node using a five-step communication mechanism; (5) The unknown node communicates with the anchor node in each communication radius in turn. The anchor node broadcasts its own information in the network. The unknown node receives the anchor node broadcast information and records its initial energy, coordinates, and RSSI value; (6) In the initial stage, the unknown node broadcasts information with a communication radius of 0.2R, forming a spatial topological structure with the anchor nodes within the range. The distance between the unknown node and all anchor nodes within the communication radius of 0.2R is calculated using the ranging positioning model in the RSSI three-dimensional ranging positioning method; (7) In order to improve the accuracy of the distance value estimated by the RSSI ranging model, the distance correction factor θ is introduced MD ; Given the coordinate information of the anchor nodes within the communication radius 0.2R, the distance correction factor is calculated based on the ratio of the actual distance between the anchor nodes to the distance estimated by the ranging model; (8) The distance D corrected by the distance correction factor is shown in formula (6): D=d×θ MD (6); (9) Using the energy loss model of wireless signals during node communication, namely the free space loss model [49], to calculate the remaining energy after node information transmission; (10) The number of unknown nodes communicating with the anchor node is its partner number F. The partner number starts from 0 and increases by 1 for each unknown node it communicates with. (11) According to step (10), the anchor nodes to be added as partners are selected, and the anchor nodes with more residual energy are selected based on the node energy loss, and the number of partners of the selected anchor nodes is increased by 1; (12) According to the five-step communication mechanism, repeat steps (6) to (11) to screen segments until four anchor nodes are selected; (13) constructing a plane triangle in space with every three nodes of the four anchor nodes selected in step (12), and calculating the normal vectors of the constructed plane triangles respectively; then projecting the plane triangle formed by the three anchor nodes in space to obtain the new anchor node projection coordinates, reconstructing the plane triangle, and calculating the angle between the normal vector and the new plane triangle; (14) Through steps (1) to (13), the angle and distance between the unknown node and the anchor node are obtained, and then the coordinates of the unknown node are calculated by combining the position estimation method.

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