CN102665272A - Wireless sensor network positioning method and system based on seed node selection - Google Patents

Abstract

The invention relates to a wireless sensor network positioning method based on seed node selection, comprising: that first distances between a to-be-positioned node and anchor nodes are acquired; that an anchor node sub-set is selected from the anchor nodes, and coordinates of the to-be-positioned node and second distances between the to-be-positioned node and every anchor node in the anchor node sub-set are calculated according to a positioning coordinate of the anchor nodes and first distances between each anchor node in the anchor node sub-set and the to-be-positioned node; that deviation medians of the first distances and the second distances are calculated, and a minimum value of the medians and a corresponding coordinate of the to-be-positioned node are collected, wherein the coordinate of the to-be-positioned node is calculated from an anchor node set corresponding to the minimum value; that anchor nodes satisfying requirements are selected to compose a target anchor node sub-set; and that a final position coordinate of the to-be-positioned node is calculated. By carrying out calculation on each anchor node sub-set, the method selects the anchor node sub-set with the minimum deviation and rejects measuring data with large errors, thereby effectively improving accuracy of positioning of the to-be-positioned node.

Description

A wireless sensor network positioning method and system based on seed node selection

technical field

The invention relates to the field of wireless communication, in particular to a wireless sensor network positioning method and system. the

Background technique

A wireless sensor network (Wireless Sensor Network, WSN) is a wireless network composed of a large number of stationary or moving sensors in a self-organizing and multi-hop manner, with the purpose of cooperatively sensing, collecting, processing and transmitting the perceived objects in the geographical area covered by the network. monitoring information and report to users. the

Wireless sensor network is a brand-new information acquisition and processing technology, which can monitor, perceive and collect information of various environments or detection objects in real time. It has the characteristics of flexibility, fault tolerance, high perception ability, low cost and rapid layout. It is used in national defense and military, environmental monitoring and forecasting, medical and health care, space exploration and other fields. the

Many specific applications in wireless sensor networks rely on the geographic location information of sensor nodes or target objects. The sensor node must know its own position in order to specify in what position or area a specific event has occurred, so as to realize the positioning and tracking of external targets. the

The existing wireless sensor network positioning methods generally use the strength value of the radio signal for positioning, which has the problem of low positioning accuracy. To improve the positioning accuracy, the simplest wireless sensor node positioning method is to install GPS for all nodes in the wireless sensor network. However, due to the fact that in practical applications, the number of wireless sensor nodes deployed in a wireless sensor network is very large, this method increases the complexity of the wireless sensor node equipment and greatly increases the use of wireless sensor networks for monitoring. the cost of. Therefore, there is currently no method and related system for realizing high-precision positioning without increasing the complexity of wireless sensor node equipment. the

Therefore, in view of the above technical problems, it is necessary to provide a wireless sensor network positioning method and system with an improved structure to overcome the above defects. the

Contents of the invention

In view of this, the purpose of the present invention is to provide a wireless sensor network positioning method and system for improving the positioning accuracy of the wireless sensor network without increasing the complexity of wireless sensor node equipment. the

To achieve the above object, the present invention provides the following technical solutions:

A wireless sensor network positioning method based on seed node selection, the wireless sensor network includes an anchor node with a known position for sending a wireless signal and an unknown node to be positioned, including:

1) According to the wireless signal received by the node to be positioned and the wireless signal attenuation model, the first distance between the node to be positioned and the anchor node sending the wireless signal is obtained, and the wireless signal includes the position coordinates of the anchor node and the The transmission power of the wireless signal;

2) From the anchor nodes corresponding to the wireless signal received by the node to be positioned, select a preset number of anchor nodes to construct a preset number of anchor node combinations;

3) Select the anchor node sub-combinations in the anchor node combination, and then calculate each anchor node sub-combination, so as to screen out the anchor nodes that meet the requirements to form the target anchor node sub-group;

4) Calculate the final position coordinates of the node to be located according to the position coordinates of the anchor nodes in the target anchor node subgroup. the

Preferably, in the above wireless sensor network positioning method, before the step 1), the method further includes: controlling the anchor node to send a wireless signal to the node to be positioned. the

Preferably, in the above wireless sensor network positioning method, the step 3) specifically includes:

31) When the anchor node combination contains N anchor nodes, select every N-k anchor nodes in the anchor node combination to set as an anchor node sub-combination, where k is a preset value less than N, and select M combinations;

32) According to the position coordinates of the anchor node and the first distance between the anchor node and the node to be located, obtain the initial position coordinates of the node to be located corresponding to each anchor node sub-combination, and a total of There are M;

33) Calculate the second distance between the node to be located and each anchor node according to the initial position coordinates of the node to be located corresponding to each anchor node in each anchor node sub-combination;

34) Calculate the deviation value between the first distance and the second distance corresponding to each anchor node in each anchor node sub-combination, and take the median value of the deviation value as the representative deviation value of each anchor node combination;

35) Use the minimum value of the representative deviation value to obtain the right, and replace the coordinates obtained by the anchor node sub-combination with the smallest representative deviation value as the tentative estimated coordinates, and then use this coordinate to obtain the undetermined node and The second distance of all anchor nodes, and calculate the deviation value between the first distance and the corresponding anchor node, and use the weight to judge whether the deviation value corresponding to each anchor node is within the allowable range, if not, discard The data of this anchor node, if it exists, keep the data of this anchor node;

36) Set up a new anchor node sub-combination according to the number of reserved anchor nodes, and make this anchor node sub-combination execute step 32). the

Preferably, in the wireless sensor network positioning method above, the wireless signal attenuation model is: Among them, p is the transmission power of the wireless signal transmitted by the corresponding anchor node, q is the wireless signal power of the corresponding anchor node received by the node to be located, d is the first distance between the node to be located and the corresponding anchor node, and a is the signal attenuation factor.

To achieve the above object, the present invention also provides the following technical solutions:

A wireless sensor network positioning system based on seed node selection, the wireless sensor network includes an anchor node whose position is known to send wireless signals and an unknown node to be positioned, which includes:

The first calculation module is used to obtain the first distance between the node to be positioned and the anchor node sending the wireless signal according to the wireless signal received by the node to be positioned and the wireless signal attenuation model;

Anchor node combination construction module, used to select anchor nodes and construct anchor node combinations with a preset number;

The target anchor node sub-combination acquisition module is used to construct the anchor node sub-combination according to the anchor node combination, and calculate the median value of the deviation value of each anchor node sub-combination as the representative deviation value of the anchor node sub-combination, and find the minimum The representative deviation value and weight of , and select the coordinates obtained by the subcombination with the smallest representative deviation as the tentative estimated coordinates, calculate the deviation value of each anchor node, and use the weight as a basis to judge whether to retain the data of known anchor nodes , so as to obtain a target anchor node sub-combination composed of anchor nodes whose deviation value of all anchor nodes is within the allowable range;

The second calculation module is configured to calculate the final position coordinates of the node to be positioned according to the anchor node subcombination. the

Preferably, in the above wireless sensor network positioning system, the target anchor node sub-combination acquisition module includes:

A setting unit, used to set an anchor node subcombination containing a preset number of anchor nodes;

An initial position coordinate calculation unit, configured to obtain the correspondence between the node to be located and each anchor node in each anchor node sub-combination according to the position coordinates of the anchor node and the first distance corresponding to each anchor node The initial position coordinates of ;

The second distance calculation unit is used to calculate and obtain the second distance between the node to be positioned and each anchor node according to the position coordinates obtained by the initial position coordinate calculation unit;

The deviation value intermediate value acquisition unit is used to calculate the coordinates obtained by each anchor node sub-combination and the first distance corresponding to each anchor node, and the intermediate value of the deviation value of the second distance;

The tentative estimated coordinate acquisition unit selects the coordinates obtained by the anchor node sub-combination with the smallest median value of the deviation value as the tentative estimated coordinates;

The final deviation value acquisition unit uses the second distance corresponding to the tentative estimated coordinates to calculate the deviation value from the first distance to the corresponding anchor node;

A judging unit, configured to judge whether the deviation value of each anchor node is within a permissible range. the

It can be seen from the above technical solutions that the wireless sensor network positioning method and system based on seed node selection in the embodiments of the present invention consider that the measurement data with large errors are included in the process of determining the position of the node to be positioned in the wireless sensor network, so , in the positioning process, after the distance between the node to be positioned and each anchor node is calculated according to the wireless signal transmitted by the anchor node, it is divided into multiple anchor node sub-combinations, and then each anchor node sub-combination is calculated, so that The anchor node sub-combination with the smallest deviation value is screened out, and the measurement data with large errors can be effectively eliminated, thereby effectively improving the positioning accuracy of the node to be positioned. Moreover, the method is based on the original radio network equipment Based on the realization, no additional equipment is added to the wireless sensor node, which reduces the use cost of the radio network. the

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings that need to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the following descriptions related to the present invention The accompanying drawings are only some embodiments of the present invention, and those skilled in the art can obtain other drawings according to these drawings without any creative effort. the

Fig. 1 is the flow chart of the wireless sensor network location method of the embodiment of the present invention;

Fig. 2 is the schematic diagram of the wireless sensor network positioning system of the embodiment of the present invention;

3 is a schematic diagram of a target anchor node sub-combination acquisition module in a wireless sensor network positioning system according to an embodiment of the present invention;

Fig. 4 is when r=0.2 of the present invention, seeks the error of 20 undetermined node coordinates;

Fig. 5 is when r=0.1 of the present invention, seeks the error of 20 undetermined node coordinates;

Fig. 6 is when r=0.06 of the present invention, seeks the error of 20 undetermined node coordinates;

Fig. 7 is when r=0.02 of the present invention, seek the error of 20 undetermined node coordinates. the

Detailed ways

The present invention discloses a wireless sensor network positioning method and positioning system based on seed node selection. The positioning method and positioning system calculate the distance between the node to be positioned and each anchor node according to the wireless signal transmitted by the anchor node. , divided into multiple anchor node sub-combinations, and then calculate each anchor node sub-combination, so as to screen out the anchor node sub-combination with the smallest deviation value, and can effectively eliminate the measurement data with large errors, thereby effectively improving the undetermined The positioning accuracy of the bit nodes, by using the positioning method and the positioning system, can solve the problem of large errors when calculating the nodes to be positioned using the existing technology. the

The technical solutions in the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention. the

As shown in Figure 1, the wireless sensor network includes an anchor node whose position is known to send wireless signals and an unknown node to be positioned. The wireless sensor network positioning method based on seed node selection provided by the present invention includes:

S1: Obtain the first distance between the node to be positioned and the anchor node sending the wireless signal according to the wireless signal received by the node to be positioned and the wireless signal attenuation model;

S2: From the anchor nodes corresponding to the wireless signal received by the node to be positioned, select a preset number of anchor nodes to construct a preset number of anchor node combinations;

S3: Select the anchor node sub-combination in the anchor node combination, and then calculate each anchor node sub-combination, so as to screen out the anchor nodes that meet the requirements to form the target anchor node sub-combination;

S4: Calculate the final position coordinates of the node to be located according to the position coordinates of the anchor nodes in the target anchor node subgroup. the

In the above step S1, the wireless signal includes the position coordinates of the anchor node and the transmission power of the wireless signal. the

In the above step S1, the formula of the wireless signal attenuation model is:

$\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; p</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}}}$

Among them, p is the transmission power of the wireless signal transmitted by the corresponding anchor node, q is the wireless signal power of the corresponding anchor node received by the node to be located, d is the distance between the node to be located and the corresponding anchor node, and a is the signal attenuation factor. In practical applications, the value of a varies with the environment. Generally, a is set to 2, but other values can also be selected as the signal attenuation factor according to actual application scenarios. the

In the above step S2, under the influence of the complex electromagnetic environment, when the anchor node sends a wireless signal to the node to be positioned, due to the influence of the environment, multipath fading and shadow fading of the signal, it is not All the wireless signals sent by the anchor nodes can be received by the nodes to be positioned, and the nodes to be positioned receive only a part of the wireless signals sent by the anchor nodes. Therefore, when constructing the combination of anchor nodes, the selected anchor nodes are the wireless An anchor node whose signal can be received by the node to be positioned. At the same time, in order to make the positioning result of the node to be positioned more accurate, the anchor nodes selected in the anchor node combination should be distributed around the node to be positioned as much as possible, so as to avoid the selected The anchor nodes are concentrated in one area, thereby affecting the calculation results. At the same time, the selected anchor nodes are distributed within an appropriate distance, so as not to be too far away from the node to be positioned, causing excessive attenuation of wireless signals during transmission. the

The above step S3 is more specifically: selecting the anchor node sub-combinations in the anchor node combination, and calculating The coordinates of the node to be positioned, using the coordinates to calculate the second distance corresponding to the node to be positioned and each of the anchor nodes and the deviation value of the corresponding first distance and the second distance, and taking the middle value of the deviation value as the described The representative deviation value of each anchor node sub-combination, use the minimum value of the representative deviation value to find the weight, and take the coordinate obtained by the anchor node sub-combination with the smallest representative deviation value as the tentative estimated coordinate, and then use this coordinate Calculate the second distance between the undetermined node and all anchor nodes again, and calculate the deviation value between the first distance and the corresponding anchor node, and judge whether the deviation value corresponding to each anchor node is within the allowable range by weight If not, the data of the anchor node is discarded, if it is, the data of the anchor node is kept, and the anchor nodes that meet the requirements are selected to form the target anchor node sub-combination. the

In the above step S4, when calculating the final position coordinates of the node to be located according to the position coordinates of the anchor nodes in the target anchor node sub-combination, the calculation method used may be the least square method or other methods. the

Further, in the actual positioning process, before the above step S1, it also includes: controlling the anchor node to send a wireless signal to the node to be positioned. the

Above-mentioned step S3 specifically comprises:

S31: When the anchor node combination contains N anchor nodes, select every N-k anchor nodes in the anchor node combination to set as an anchor node sub-combination, where k is a preset value less than N, and select M combinations;

S32: According to the position coordinates of the anchor node and the first distance between the anchor node and the node to be located, obtain the initial position coordinates of the node to be located corresponding to each anchor node sub-combination, a total of There are M;

S33: Calculate the second distance between the node to be located and each anchor node according to the initial position coordinates of the node to be located corresponding to each anchor node in each anchor node sub-combination;

S34: Calculate the deviation value between the first distance and the second distance corresponding to each anchor node in each anchor node sub-combination, and take the median value of the deviation value as the representative deviation value of each anchor node combination;

S35: Use the minimum value of the representative deviation value to find the right, and take the coordinate obtained by the anchor node sub-combination with the smallest representative deviation value as the tentative estimated coordinate, and then use this coordinate to find the relationship between the undetermined node and The second distance of all anchor nodes, and calculate the deviation value between the first distance and the corresponding anchor node, and use the weight to judge whether the deviation value corresponding to each anchor node is within the allowable range, if not, discard The data of this anchor node, if it exists, keep the data of this anchor node;

S36: Set a new anchor node sub-combination according to the number of reserved anchor nodes, and make this anchor node sub-combination execute step 32), but only generate one target position coordinate. the

In the above step S31, assuming that in the anchor node combination, there is a large error between the first distance corresponding to the anchor node with a percentage e and the actual value, a set of first distance and the actual value can be obtained according to the probability P The actual distance is consistent or the value of M and k is small, and every k anchor nodes are set as an anchor node sub-combination. If P>=0.99, there must be an anchor node sub-combination, and the anchor node The corresponding first distance is consistent with the actual value or the error is small. Therefore, by setting the anchor node sub-combination, the wrong data can be eliminated. In addition, the value of k can be a preset value greater than or equal to 3;

In the above step S32, in the process of calculating the position coordinates of the node to be positioned, the method of least squares may be used for calculation, but other methods may also be used. the

The above step S34 is specifically: calculating the deviation value representing each anchor node sub-combination, and finding the deviation value between the first distance and the second distance of the anchor node corresponding to the initial coordinate value, wherein the first distance is represented by d, and the first distance is set The second distance is represented by D, and the middle value is taken as the representative deviation value of the anchor node sub-combination corresponding to this coordinate value, and r is used to represent the difference between the first distance and the second distance, and the representative deviation value can be taken as R=med r, of course, other ways can also be selected to calculate the deviation value, for example, setting the deviation value as the absolute value of the difference between the first distance and the second distance, this application does not limited. the

The above step S35 is specifically as follows: select the undetermined node coordinates corresponding to the anchor node sub-combination with the smallest representative deviation value R as the tentative estimated coordinates, take the smallest representative deviation value R to obtain the weight w, and use the tentative estimated coordinates Find the second distance from each anchor node, find the deviation value of the corresponding first distance and the second distance as the final deviation value of each anchor node, and according to the weight and parameter u (depending on the strength of the noise, The greater the noise intensity, the smaller the value) to judge whether the aforementioned deviation value is within the allowable range, if not, discard the anchor node data, if yes, keep and form the target anchor node sub-combination, and use the least square method or other methods to find out Final undetermined node coordinates. the

The solution provided by the present invention will be described in detail below in conjunction with specific embodiments. the

In the 100m×100m monitoring area, multiple sensor nodes are deployed in the monitoring area, among which s1-s16 are 16 anchor nodes, and these 16 anchor nodes are set as an anchor node combination for subsequent positioning of the nodes to be positioned. us is a node to be located. Assume that the position coordinates of the 16 anchor nodes in the anchor node combination are s1 (0, 0), s2 (0, 10), s3 (0, 20), s4 (0, 30), s5 (10, 0), s6(10,10), s7(10,20), s8(10,30), s9(20,0), s10(20,10), s11(20,20), s12(20,30), s13 (30, 0), s14(30, 10), s15(30, 20), s16(30, 30), and assume that the coordinates of the node to be located are us(15, 15). the

The 16 anchor nodes in the anchor node combination periodically transmit wireless signals, and the wireless signals include the location coordinates of the anchor nodes, which are the above-mentioned location coordinates s1-s16, and the wireless signal transmission power p. The node to be positioned receives the radio transmission signal of the anchor node, and then, according to the wireless signal attenuation model, calculates the first distance d between the anchor node and the node to be positioned us, wherein, according to the wireless signal attenuation model formula:

$\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; p</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}^{\mathrm{<span\; class="notranslate">\; a</span>}}}$

Among them, p is the transmission power of the wireless signal transmitted by the corresponding anchor node, q is the wireless signal power of the corresponding anchor node received by the node to be located, d is the distance between the node to be located and the corresponding anchor node, and a is the signal attenuation factor. In practical applications, the value of a varies with the environment. the

In this experiment, the attenuation factor a is set to 2. Therefore, the first distance between the node us to be located and the 16 anchor nodes can be obtained by calculation: d1=22.0407, d2=16.0244, d3=16.4001, d4= 21.5766, d5 = 16.3589, d6 = 7.7486, d7 = 7.4429, d8 = 15.4861, d9 = 15.9667, d10 = 7.3526, d11 = 7.5234, d12 = 15.9372, d13 = 21.2987, d14 = 16.4274, d15 = 2, 0.05 the

It is explained here that at least three sets of data are required to locate a point, so here we select at least 3 anchor nodes as a group. In this experiment, we select 4 anchor nodes as a group. The probability of being too close to the situation where the coordinates of the undetermined node cannot be obtained requires at least 4 correct or small error data in our anchor node, but in practice, considering the computing power of the anchor node and the required algorithm accuracy, we cannot calculate all possible combinations, but we must have at least one node combination with a small data error, only in this way can we get the undetermined node coordinates with a small error, and we can make at least one node combination with a small error If the probability is greater than 99%, we must consider selecting an appropriate anchor node sub-combination number M. the

In this experiment, M=20 is selected, so that a 30% pollution rate (the proportion of the anchor node with a large error) can be tolerated, and the noise follows a Gaussian distribution, assuming that there are 4 wrong data, that is, the error is large , and assuming that the erroneous data bits are d4, d8, and d12, according to the above method, 4 anchor nodes are randomly selected from the 16 anchor nodes as anchor node sub-combinations, and a total of 20 groups are selected. Theoretically speaking, these 20 The probability that at least one set of data in the group is correct is greater than 99.5%, that is, the probability that one of the 20 groups does not have the four data of d4, d8, and d12 is greater than 99.5%. The settings of the 16 anchor node sub-combinations described in an experiment can be found in the table below. For each of the above-mentioned anchor node sub-combinations, the initial position coordinates of the nodes to be located are calculated by the method of least squares, and then we can get The results in the following table:

It can be seen from the above table that the representative deviation value of the 8th group is the smallest, so the undetermined node coordinates calculated by this group are selected as the tentative estimated coordinates, which are (15.3717, 15.2254), and the undetermined nodes and known anchors are calculated again with this coordinate The second distance of the node, and calculate the deviation value da between the second distance and the first distance, the result is as follows:

Anchor node number S1 S2 S3 S4 S5 S6 |da|/10^4 0.4050 0.2112 0.3040 0.4558 0.2137 0.2546 Anchor node number S7 S8 S9 S10 S11 S12 |da|/10^4 0.2560 0.6347 0.0534 0.3722 0.8737 0.4546 Anchor node number S13 S14 S15 S16 the the |da|/10^4 0.1847 0.8938 0.4777 0.0086 the the

Then through the representative error U8 of the 8th group, we can use the formula: S0＝1.4826*(1+5/14)*((U)^2)^0.5 and select the value of the parameter r, and then judge ||da| /S0|<r Calculate the weight of each anchor node. The principle is that if the inequality holds, the weight of the anchor node is 1, otherwise it is 0. Here we choose r=0.02 (the value of r is different in different environments, when the noise is large, a smaller value must be selected to ensure that the system can accurately judge the anchor node data with large errors), through Calculate the weight of each anchor node as:

node number S1 S2 S3 S4 S5 S6 S7 S8 right 0 1 1 0 1 1 1 0 node number S9 S10 S11 S12 S13 S14 S15 S16 right 1 S 0 0 1 0 0 1

[0082] An anchor node with a weight of 1 is selected to be combined into a target anchor node sub-combination, and the final coordinate value of the fixed node is obtained by this combination (15.4382, 15.2405).

Next, we use experiments to see the impact of different r values on the system. We select r=0.2, r=0.1, r=0.06, r=0.02 to find the coordinates of the undetermined nodes 20 times, and what is the difference in the error of the undetermined nodes obtained. the

The above four pictures are respectively r=0.2, r=0.1, r=0.06, r=0.02, the error values obtained by calculating the coordinates of the undetermined nodes 20 times, and the points on the line 100 (solid line) represent the calculated tentative The error of the estimated coordinate value of , the point on the line 200 (dotted line) represents the final coordinate error value. From the above picture, we can see that as the value of r decreases generally, the point on the line 200 is far from The closer the x-axis is, the smaller the error is, so the following conclusions are obtained:

In the case of a certain noise level, the smaller the r value, the more accurate and stable coordinates of undetermined nodes can be obtained, but the smaller the r value, the better. When the r value is too small, there will be cases where the fixed node cannot be obtained. This is because when the value of r is small, the range of the allowable deviation value is too small, and some anchor nodes with small errors are also eliminated by the weight, so the value of r should be appropriate. the

As shown in Figure 2, the wireless sensor network positioning system based on seed node selection provided by the present invention includes:

S11: a first calculation module, used to obtain the first distance between the node to be positioned and the anchor node sending the wireless signal according to the wireless signal received by the node to be positioned and the wireless signal attenuation model;

S12: An anchor node combination construction module, used to select anchor nodes and construct anchor node combinations with a preset number;

S13: The target anchor node sub-combination acquisition module, which is used to construct the anchor node sub-combination according to the anchor node combination, and calculate the median value of the deviation value of each anchor node sub-combination as the representative deviation value of the anchor node sub-combination, and calculate Find the smallest representative deviation value and weight, and select the coordinates obtained by the subcombination with the smallest representative deviation as the tentative estimated coordinates, calculate the deviation value of each anchor node, and use the weight as a basis to judge whether to retain known anchor nodes data, so as to obtain a target anchor node sub-combination composed of anchor nodes whose deviation value of all anchor nodes is within the allowable range;

S14: A second calculation module, configured to calculate the final position coordinates of the node to be located according to the anchor node subcombination. the

As shown in Figure 3, the above target anchor node sub-combination acquisition module S13 also includes:

S131: a setting unit, used to set an anchor node sub-combination containing a preset number of anchor nodes;

S132: An initial position coordinate calculation unit, configured to obtain each anchor node in the node to be located and each anchor node sub-combination according to the position coordinates of the anchor node and the first distance corresponding to each anchor node Corresponding initial position coordinates;

S133: The second distance calculation unit is used to calculate and obtain the second distance between the node to be positioned and each anchor node according to the position coordinates obtained by the initial position coordinate calculation unit;

S134: a deviation value intermediate value acquisition unit, which is used to calculate the intermediate value of the deviation value of the first distance and the second distance corresponding to the coordinates obtained by each anchor node sub-combination and each anchor node;

S135: The tentative estimated coordinate acquisition unit selects the coordinate obtained by the anchor node sub-combination with the smallest median value of the deviation value as the tentative estimated coordinate;

S136: The final deviation value acquisition unit uses the second distance corresponding to the provisional estimated coordinates to calculate the deviation value from the first distance to the corresponding anchor node;

S137: A judging unit, configured to judge whether the deviation value of each anchor node is within an allowable range. the

In the wireless sensor network positioning method and system based on seed node selection in the embodiment of the present invention, it is considered that the process of determining the position of the node to be positioned in the wireless sensor network contains measurement data with large errors. Therefore, in the positioning process, according to the anchor After the wireless signal transmitted by the node calculates the distance between the node to be positioned and each anchor node, it is divided into multiple anchor node sub-combinations, and then each anchor node sub-combination is calculated, so as to screen out the anchor node with the smallest deviation value sub-combination, and can effectively eliminate the measurement data with large errors, thereby effectively improving the positioning accuracy of the node to be positioned. Moreover, the method is implemented on the basis of the original radio network equipment, and is not in the Additional devices are added to the wireless sensor nodes, reducing the cost of using the radio network. the

It will be apparent to those skilled in the art that the invention is not limited to the details of the above-described exemplary embodiments, but that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Accordingly, the embodiments should be regarded in all points of view as exemplary and not restrictive, the scope of the invention being defined by the appended claims rather than the foregoing description, and it is therefore intended that the scope of the invention be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in the present invention. Any reference sign in a claim should not be construed as limiting the claim concerned. the

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art. the

Claims (6)

1. A wireless sensor network positioning method based on seed node selection, comprising known anchor nodes for sending wireless signals and unknown nodes to be positioned in the wireless sensor network, characterized in that: comprising: 1) According to the wireless signal received by the node to be positioned and the wireless signal attenuation model, the first distance between the node to be positioned and the anchor node sending the wireless signal is obtained, and the wireless signal includes the position coordinates of the anchor node and the The transmission power of the wireless signal; 2) Selecting a preset number of anchor nodes from the anchor nodes corresponding to the wireless signal received by the node to be positioned to construct a preset number of anchor node combinations; 3) Select the anchor node sub-combinations in the anchor node combination, and then calculate each anchor node sub-combination, so as to screen out the anchor nodes that meet the requirements to form the target anchor node sub-group; 4) Calculate the final position coordinates of the node to be located according to the position coordinates of the anchor nodes in the target anchor node subgroup. 2. The wireless sensor network positioning method according to claim 1, characterized in that: before step 1), it further comprises: controlling the anchor node to send a wireless signal to the node to be positioned. 3. The wireless sensor network positioning method according to claim 1, characterized in that: step 3) specifically includes: 31) When the anchor node combination contains N anchor nodes, select every N-k anchor nodes in the anchor node combination to set as an anchor node sub-combination, where k is a preset value less than N, and select M combinations; 32) According to the position coordinates of the anchor node and the first distance between the anchor node and the node to be located, obtain the initial position coordinates of the node to be located corresponding to each anchor node sub-combination, and a total of There are M; 33) Calculate a second distance between the node to be located and each anchor node according to the initial position coordinates of the node to be located corresponding to each anchor node in each anchor node sub-combination; 34) Calculate the deviation value between the first distance and the second distance corresponding to each anchor node in each anchor node sub-combination, and take the median value of the deviation value as the representative deviation value of each anchor node combination; 35) Use the minimum value of the representative deviation value to obtain the right, and replace the coordinate obtained by the anchor node sub-combination with the smallest representative deviation value as the tentative estimated coordinate, and then use this coordinate to obtain the undetermined node and The second distance of all anchor nodes, and calculate the deviation value between the first distance and the corresponding anchor node, and use the weight to judge whether the deviation value corresponding to each anchor node is within the allowable range, if not, discard The data of this anchor node, if it exists, keep the data of this anchor node; 36) Set up a new anchor node sub-combination according to the number of reserved anchor nodes, and make this anchor node sub-combination execute step 32). 4. The wireless sensor network positioning method according to claim 1, characterized in that: the wireless signal attenuation model is:

Among them, p is the transmission power of the wireless signal transmitted by the corresponding anchor node, q is the wireless signal power of the corresponding anchor node received by the node to be located, d is the first distance between the node to be located and the corresponding anchor node, and a is the signal attenuation factor. 5. A wireless sensor network positioning system based on seed node selection, the wireless sensor network includes a known anchor node for sending wireless signals and an unknown node to be positioned, characterized in that: comprising: A first calculation module, configured to obtain a first distance between the node to be positioned and the anchor node sending the wireless signal according to the wireless signal received by the node to be positioned and the wireless signal attenuation model; An anchor node combination construction module, used for selecting anchor nodes and constructing anchor node combinations with a preset number; The target anchor node sub-combination acquisition module is used to construct the anchor node sub-combination according to the anchor node combination, and calculate the median value of the deviation value of each anchor node sub-combination as the representative deviation value of the anchor node sub-combination, and find the minimum The representative deviation value and weight of , and select the coordinates obtained by the subcombination with the smallest representative deviation as the tentative estimated coordinates, calculate the deviation value of each anchor node, and use the weight as a basis to judge whether to retain the data of known anchor nodes , so as to obtain a target anchor node sub-combination composed of anchor nodes whose deviation values of all anchor nodes are within the allowable range; The second calculation module is configured to calculate the final position coordinates of the node to be positioned according to the anchor node subcombination. 6. The wireless sensor network positioning system according to claim 5, characterized in that: the sub-combination acquisition module of the target anchor node comprises: A setting unit, used to set an anchor node sub-combination containing a preset number of anchor nodes; An initial position coordinate calculation unit, configured to obtain the correspondence between the node to be positioned and each anchor node in each anchor node sub-combination according to the position coordinates of the anchor node and the first distance corresponding to each anchor node The initial position coordinates of ; The second distance calculation unit is used to calculate and obtain the second distance between the node to be positioned and each anchor node according to the position coordinates obtained by the initial position coordinate calculation unit; The deviation value intermediate value acquisition unit is used to calculate the intermediate value of the deviation value of the first distance and the second distance corresponding to the coordinates obtained by each anchor node sub-combination and the respective anchor nodes; The tentative estimated coordinate acquisition unit selects the coordinate obtained by the anchor node sub-combination with the smallest median value of the deviation value as the tentative estimated coordinate; The final deviation value acquisition unit uses the second distance corresponding to the provisional estimated coordinates to calculate the deviation value from the first distance to the corresponding anchor node; A judging unit, configured to judge whether the deviation value of each anchor node is within a permissible range.

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