A lora wireless sensor coverage method

Abstract

The application discloses a lora wireless sensor covering method, a plurality of hexagonal prisms are used to fill a cylindrical three-dimensional region M, sensor nodes are randomly arranged in the three-dimensional region, and the maximum k sensor nodes are in a working state in each hexagonal prism region, then the coverage multiplicity of monitoring target points is acquired in a time manner, and the sensor nodes around the monitoring target points with insufficient coverage multiplicity are woken up, so that the covering holes caused by the insufficient energy of the sensor nodes can be better prevented.

Description

Technical Field

[0001] This invention relates to the field of wireless sensor node network technology, and more particularly to a LoRa wireless sensor coverage method. Background Technology

[0002] In WSNs (Wireless Networking Systems), the network lifetime is typically defined as the maximum time a sensor node can remain connected while maintaining network coverage. Target coverage is a typical coverage category, and coverage of multiple monitoring target points is an important implementation method. To obtain accurate and detailed data, a large number of sensor nodes are needed to monitor these monitoring target points and send the sensed data to the sink.

[0003] If a monitoring target point is covered by K sensor nodes, it is said to be covered k times, meaning the coverage multiple of the monitoring target point is k. When all monitoring target points in a 3D region M are covered k times, the 3D region M is said to be covered K times. Generally, the higher the coverage multiple of a monitoring target point, the better the coverage quality. However, using too many sensor nodes to monitor the same monitoring target point leads to a large amount of redundant data, resulting in wasted node energy. If the number of sensor nodes monitoring the same monitoring target point is reduced, the corresponding sensing data will also decrease, and subsequently, the energy consumed by sensing and transmission will also decrease. These reduced nodes can enter a dormant mode to reduce energy consumption. When the energy of active nodes is exhausted, these dormant nodes can be woken up to maintain network coverage and effectively extend the network lifetime.

[0004] Existing sensor node scheduling methods use spatial tessellation to fill each layer of the target space with cubes or truncated octahedrons as filling sub-units, and deploy sensor nodes on the vertices of the polyhedra to reduce redundancy and energy waste in redundant coverage. However, these methods are very complex and neglect the case of random coverage. In addition, most of these methods divide the target space into cubic shapes, ignoring node deployment strategies when the target space is a cylindrical three-dimensional region such as a tunnel or subway track. Summary of the Invention

[0005] The purpose of this invention is to provide a LoRa wireless sensor coverage method to overcome the above-mentioned defects in the prior art.

[0006] A method for covering LoRa wireless sensors includes the following steps:

[0007] Step S1: Divide the three-dimensional region M into polyhedra {M1, M2, M3, ..., M}. N Let the polyhedron M be... i The overlapping region of the circumsphere and the circumsphere of its adjacent polyhedron is B. i= {b i1 , b i2 , …, b in};

[0008] Step S2: Deploy P0 sensor nodes in the three - dimensional region M. The sensor nodes can send position signals, and the position signals include the coordinates of the sensor nodes;

[0009] Step S3: Wake up all the sensor nodes in the polyhedron M i , count the number w of the sensor nodes located in B i , compare it with the preset coverage multiplicity k. If w > k, keep k nodes working and put the remaining nodes in the polyhedron M i to sleep; if w ≤ k, keep w nodes working and put the remaining nodes in the polyhedron M i to sleep;

[0010] Step S4: Increment the value of i in Step S3 by 1, return to Step S3 until i = N, and record the coordinates of the sensor nodes that are working at this time;

[0011] Step S5: Calculate the probability that the monitoring target point is covered by the sensor node S i , count the coverage multiplicity k j of the monitoring target point, compare the coverage multiplicity k j with the preset coverage multiplicity k, and count the number Q1 of monitoring target points that satisfy k j < k;

[0012] Step S6: If the number Q1 of monitoring target points is less than or equal to the preset value Q0, after a preset time T0, return to Step S5. If the number Q1 of monitoring target points is greater than the preset value Q0, perform Step S7:

[0013] Step S7: Denote the monitoring target points with coverage multiplicity less than k as (x l ′ , y l ′ , z l ′ ), and its coverage multiplicity is k l ′ . Calculate the number of sensor nodes in the sphere with the monitoring target point (x l ′ , y l ′ , z l ′ ) as the center of the sphere and radius R s that are in the sleep state and the monitoring target point (x l ′ , yl ′ ,z l ′ The distance to the monitoring target point (x) is used to sequentially wake up the monitoring target point (x) at the distance to the monitoring target point. l ′ ,y l ′ ,z l ′ (Recent KK) l ′ The sensor node is in a dormant state. After the preset time T0, the process returns to step S5.

[0014] Preferably, let polyhedron M be... i The overlapping region of the circumsphere and the circumsphere of its adjacent polyhedron is B. i ={b i1 ,b i2 ,…,b in In step S3, if w > k, wk B's are put into hibernation using a random hibernation method. i The sensor node in the middle, the polyhedron M in dormancy i The content does not include the B mentioned above. i All sensor nodes in the region; if w ≤ k, the polyhedron M is put into hibernation. i The content does not include the B mentioned above. i All the sensor nodes in the region.

[0015] Preferably, in step S1, the polyhedron M i With M i-1 M i+1 Adjacent.

[0016] Preferably, in step S1, the three-dimensional region M is cylindrical; the polyhedron is a cube.

[0017] Preferably, in step S1, the three-dimensional region M is cylindrical; the polyhedron is a regular hexagonal prism.

[0018] Preferably, in step S1, the three-dimensional region M is cylindrical; the polyhedron is a truncated octahedron.

[0019] Preferably, in step S2, the sensor node is in a stationary state.

[0020] Preferably, in step S3, the coverage multiplicity k is 2.

[0021] Preferably, in step S2, the node deployment method is random deployment.

[0022] The above technical solution has the following advantages or beneficial effects:

[0023] This invention's LoRa wireless sensor coverage method uses regular hexagonal prisms to fill a three-dimensional region, enabling the division of cylindrical regions such as tunnels and subway tracks. This increases the volume of polyhedra required to fill a unit coverage weight, reduces the number of polyhedra required to fill a three-dimensional region M, and reduces the number of sensor nodes that need to be kept awake a unit coverage weight, thereby improving sensor node utilization efficiency. The method is easy to implement. By periodically acquiring the coverage weight of the monitoring target point and waking up sensor nodes around the monitoring target point with insufficient coverage weight, it can effectively prevent coverage holes caused by insufficient energy of sensor nodes. Attached Figure Description

[0024] Figure 1 This is a flowchart of a LoRa wireless sensor coverage method according to an embodiment of the present invention. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Combination Figure 1 As shown, a LoRa wireless sensor coverage method includes the following steps:

[0027] Step S1: Divide the three-dimensional region M into multiple polyhedra {M1, M2, M3, ..., M}. N Specifically, the three-dimensional region M is divided into multiple layers, using a polyhedron M. i Each layer of the target space is filled as a filling sub-unit, where the sum of the volumes of the polyhedra is greater than the volume of the three-dimensional region M. Let the overlapping region of the circumscribed sphere of polyhedron M1 and the circumscribed spheres of its adjacent polyhedra be B1 = {b 11 ,b 12 ,…,b 1n}, polyhedron M i The overlapping region of the circumsphere and its adjacent polyhedral circumsphere is B. i ={b i1 ,b i2 ,…,b in}, where i = 1, 2, ..., N, and all overlapping regions within the three-dimensional region are B = {B1, B2, ..., B}. n};Polyhedron M i With M i-1 M i+1Adjacent (except when i = 1 or N), where the three-dimensional region M is cylindrical with a base radius of R0 and a height of H0; the polyhedron is a regular hexagonal prism, which can more fully divide the cylindrical three-dimensional region compared to other polyhedra such as cubes and truncated octahedrons; when sensor nodes are randomly deployed in the overlapping area of ​​adjacent regular hexagonal prisms, the network can achieve full coverage with the fewest nodes; the base side length of the regular hexagon in the regular hexagonal prism is a, and the height is a; N represents the number of regular hexagonal prisms; n is the number of adjacent regular hexagonal prisms; the regular hexagonal prisms gradually fill inward from the side of the cylindrical three-dimensional region.

[0028] Step S2: Randomly deploy P0 sensor nodes {S1, S2, ..., S} in the three-dimensional region M. P0 Furthermore, the sensor nodes can be randomly arranged within the overlapping region B, and the sensor nodes can send position signals to the sink. These position signals include information about the sensor nodes S. sn coordinates (x) sn ,y sn ,z sn ), where 1≤sn≤P0, the communication radius of the sensor node can be between 1000-2000 meters. The sensor node is stationary or moves less than 20 meters, so these sensor nodes can be regarded as stationary.

[0029] The sensor node's sensing radius is set to R. s The communication radius is set to R. c , where R c ≥2R s To ensure the connectivity of the coverage network, sensor node S i′ The range of perception is based on (x sn ,y sn ,z sn With ) as the center and radius R s A sphere, the volume of which is... To ensure that all points within a regular hexagonal prism can be covered by any node placed within the prism, take...

[0030] Step S3: Set i = 1, wake up M i All sensor nodes in the system are activated, ensuring they are operational. Statistics are located in B. i The number of sensor nodes w is compared with the preset coverage weight k. If w > k, wk B nodes are randomly put into sleep mode. i Sensor nodes in the middle, dormant M i B is not included. i All sensor nodes in the region; if w≤k, M goes into sleep mode. i B is not included. iAll sensor nodes in the area. The preset coverage multiplicity k is 2.

[0031] Step S4: Increment the value of i in Step S3 by 1, and repeat Step S3 until i = N. Record the coordinates (x sn′ , y sn′ , z sn′ ) of the sensor nodes in operation, where 1 ≤ sn′ ≤ P1 and P1 is the number of sensor nodes in operation.

[0032] Step S5: Use the Boolean model to calculate the probability that the monitoring target point (x j ′, y j ′, z j ′) is covered by the sensor node S sn′ (1 ≤ sn′ ≤ P1):

[0033]

[0034] Where

[0035] (x sn′ , y sn′ , z sn′ ) are the coordinates of the sensor node S sn′ ; d(i, j) is the distance between the monitoring target point (x j ′, y j ′, z j ′) and the sensor node S sn′ . The monitoring target point (x j ′, y j ′, z j ′) can be the vertices of each polyhedron, where 1 ≤ j ≤ Q and Q is the total number of vertices of the polyhedra in M.

[0036] Count the coverage multiplicity k j ′, y j ′, z j ′) of the monitoring target point, compare k j with the preset coverage multiplicity k, and count the number Q1 of monitoring target points that satisfy k j < k. j <k.

[0037] Step S6: If Q1 is less than or equal to the preset value Q0, it means that there are fewer coverage holes and the node coverage rate is higher. After a preset time T0, return to Step S5, where Q0 can be indicating rounding down; if Q1 is greater than the preset value Q0, proceed to Step S7:

[0038] Step S7: Denote the monitoring target points with a coverage multiplicity less than k as (x l ′, yl ′,z l ′), whose covering multiplicity is k. l ′, where 1≤l≤Q0, calculate to monitor target point (x l ′,y l ′,z l Let ′ be the center of the sphere and radius be R. s Sensor nodes in a dormant state within the sphere and the monitoring target point (x) l ′,y l ′,z l The distance to the target point (x') is used to sequentially wake up the distance monitoring target point (x'). l ′,y l ′,z l ′) Recent kk l A sleep sensor node is selected. After a preset time T0, the process returns to step S5 to prevent any sensor node from failing due to insufficient power. The preset time T0 can be 30-180 minutes.

[0039] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

[0040] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

Claims

1. A method for covering LoRa wireless sensors, characterized in that, Includes the following steps: Step S1: Divide the three-dimensional region M into regular hexagonal prisms {M1, M2, M3, ..., M}. N }; Step S2: Deploy P0 sensor nodes in the three-dimensional region M. The sensor nodes can send position signals, which include the coordinates of the sensor nodes. Step S3: Let M be a regular hexagonal prism i The overlapping region between the circumscribed sphere and the circumscribed sphere of the adjacent regular hexagonal prism is B. i ={b i1 ,b i2 ,…,b in }, for the regular hexagonal prism M i All sensor nodes mentioned above are woken up, and the statistics located in B are counted. i The number of sensor nodes w is compared with a preset coverage weight k. If w > k, k nodes are kept active, and the regular hexagonal prism M is put into sleep mode. i Remaining nodes; if w ≤ k, keep w nodes active, and put the regular hexagonal prism M into a dormant state. i Remaining nodes; Step S4: Increment the value of i in step S3 by 1, return to step S3, until i = N, and record the coordinates of the sensor node that is in working state at this time; Step S5: Calculate the probability that the monitoring target point is covered, and count the coverage multiplicity k of the monitoring target point j , and compare the coverage multiplicity k j with the preset coverage multiplicity k, and count the number Q1 of monitoring target points that satisfy k j < k; Step S6: If the number of monitoring target points Q1 is less than or equal to the preset value Q0, after a preset time T0, return to step S5; if the number of monitoring target points Q1 is greater than the preset value Q0, proceed to step S7. Step S7: Denote the monitoring target points with a coverage multiplicity less than k as (x l ′ ,y l ′ ,z l ′ Let the monitoring target point (x) be... l ′ ,y l ′ ,z l ′ The coverage multiplicity of ) is k l ′ , sequentially wake up the monitoring target points (x) at a distance of 100 km. l ′ ,y l ′ ,z l ′ (Recent KK) l ′ After the preset time T0, the dormant sensor node returns to step S5.

2. The LoRa wireless sensor coverage method as described in claim 1, characterized in that, In step S3, if w > k, wk Bs are put into hibernation using a random hibernation method. i The sensor node in the middle, the regular hexagonal prism M is in a dormant state. i The content does not include the B mentioned above. i All sensor nodes in the region; if w ≤ k, the regular hexagonal prism M is put into sleep mode. i The content does not include the B mentioned above. i All the sensor nodes in the region.

3. The LoRa wireless sensor coverage method as described in claim 1, characterized in that, In step S2, the node deployment method is random deployment.

4. The LoRa wireless sensor coverage method as described in claim 1, characterized in that, In step S1, the regular hexagonal prism M i With M i-1 M i+1 Adjacent.

5. The LoRa wireless sensor coverage method as described in claim 1, characterized in that, In step S1, the three-dimensional region M is cylindrical; the regular hexagonal prism is a cube.

6. The LoRa wireless sensor coverage method as described in claim 1, characterized in that, In step S2, the sensor node is in a stationary state.

7. The LoRa wireless sensor coverage method as described in claim 1, characterized in that, In step S3, the coverage multiplicity k is 2.

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