CN101191832A - Wireless sensor network node position finding process based on range measurement - Google Patents

Abstract

The invention relates to a method for positioning wireless sensor network nodes on the basis of the ranging technology, comprising at least three positioned anchor nodes, a node to be detected and background positioning center. The invention is characterized in that: 1) the positioned anchor nodes periodically sends beacon signals for positioning at a fixed frequency; 2) the node to be detected sends the receiving signal intensity for receiving the beacon signals to a gateway anchor node; 3) the gateway anchor node transmits the receiving signal intensity of the node to be detected and the transmitting signal intensity of the anchor nodes to the background positioning center; 4) the background positioning center calculates the distances between the node to be detected and the anchor nodes; 5) the background positioning center calculates the coordinate of the node to be detected. The invention calculates the distances between the node to be detected and the anchor nodes according to the difference between the transmitting signal intensity of the anchor nodes and the receiving signal intensity of the node to be detected and positions the coordinate of the node to be detected according to the differences between the distances from the node to be detected to the anchor nodes, thereby reducing the positioning error and improving the accuracy of the positioning.

Description

A kind of wireless sensor network node locating method based on range finding

Technical field

The present invention relates to a kind of wireless sensor network node locating method based on ranging technology.

Background technology

Wireless sensor network can be applicable to connect up and power supply is supplied with the zone that difficulty, personnel can not arrive (as be subjected to polluting, environment can not destroyed or hostile area) and some interim occasions (as the generation disaster time, fixed communication network is destroyed) etc.It does not need the fixed network support, have rapid deployment, characteristics such as survivability is strong can be widely used in fields such as military affairs, industry, traffic, environmental protection, particularly for Military Application, target tracking, environment measuring, space exploration, the advantage of wireless sensor network is more and more obvious.

Form network by disposing a large amount of wireless sensers to target area, each wireless senser is called a node of wireless sensor network.For most wireless sensor network, do not know sensing station and the data of perception are nonsensical.Sensor node must clear and definite self-position could describe " where or zone particular event has taken place " in detail, realizes location and tracking to external object.And the acquisition of node location information can make network designer optimize the application of wireless sensor network in others, such as to route optimization Algorithm, allied signal processing, the optimization of communication overhead, location-based information inquiry, network coverage inspection etc.And manually dispose and the restriction that gps receiver all can be subjected to problems such as cost, power consumption, extendability is installed for the all-network node, even may can't realize in some occasion at all, as indoor since be subjected to buildings stop that its positioning performance is unsatisfactory, therefore must adopt certain technological means to realize the self poisoning of sensor node in the wireless sensor network.In wireless sensor network, the communication distance of the big and stochastic distribution of sensor node finite energy, poor reliability, node scale, wireless module is limited, and this localization method and location technology to sensor node has proposed very high requirement.

In the prior art, the node of a small amount of known location obtains the positional information of other unknown position nodes in the general using wireless sensor network; The node of above-mentioned known location is called anchor node, and the node of unknown position is called unknown node or node to be measured.Existing wireless sensor network node self positioning method mainly contains two kinds: promptly based on the localization method of ranging technology and the localization method of non-distance measuring.The position that calculates node to be measured based on the localization method of ranging technology distance or the angle information by point-to-point between measured node, the precision of said method is higher, but the hardware to node has also proposed very high requirement, and need usually repeatedly to measure, the circulation refinement can produce a large amount of calculating and communication overhead when obtaining relative accurate localization result, so, though this method bearing accuracy is higher, is not suitable for low-power consumption, cheaply application.

The localization method of non-distance measuring need not distance and angle information, only the information such as anchor node according to network connectivty and known location just can realize relative accurate localization function, but the precision of the localization method of non-distance measuring and speed of convergence depend on the precision that the average every hop distance of network is estimated to a certain extent, and when sensor network anisotropy or topological structure more complicated the performance of algorithm with obvious variation.For example publication number is that (number of patent application: Chinese invention patent CN200710062844.9) " convex programming positioning method of triangle filtering of wireless sensor network " discloses a kind of like this wireless sensor node localization method method of non-distance measuring to CN101004448, and it comprises: the anchor node broadcast transmission comprises the information of self-position; Unknown node receives the information that anchor node sends; When unknown node received the information of two above anchor nodes, calculating with each anchor node that receives was the center of circle, and communication radius is the intersecting area of the circle of radius; According to unknown node whether in the triangle that any three anchor nodes that receive are formed and the intersecting area of described circle unknown node is positioned: judge in the triangle of any three anchor nodes composition whether unknown node is receiving, if unknown node is not in the triangle that any three anchor nodes are formed, then with the barycenter of the minimum rectangle of the intersecting area that the comprises described circle position as unknown node; Otherwise the leg-of-mutton intersecting area that any three anchor nodes that calculate the unknown node place are formed is with the barycenter of the minimum rectangle of the intersecting area that comprises leg-of-mutton intersecting area and the described circle position as unknown node.Above-mentioned localization method key is that the attenuation degree by measuring-signal comes the distance between estimating target node and 3 the above anchor nodes, under the known condition of anchor node coordinate, with 3 anchor node coordinates is the center of circle, the distance of node to be measured and anchor node is that radius is drawn circle, and then the intersection point of 3 circles is the position of node to be measured.This localization method can be applied on the existing wireless sensor network node platform, but this method is subject to Effect of Environmental such as temperature, humidity, barrier, multipath easily, and bearing accuracy is not high.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of bearing accuracy height at above-mentioned prior art, is not subject to such environmental effects, and the low wireless sensor network node locating method based on ranging technology of cost.

The present invention solves the problems of the technologies described above the technical scheme that is adopted: this wireless sensor network node locating method, the anchor node that comprises at least three location awares, the node to be measured of position the unknown and the backstage centre of location, have at least an anchor node to link to each other with the backstage centre of location by network as the gateway anchor node at least in the anchor node of described three location awares, it is characterized in that: described wireless sensor network node locating method is realized by following steps:

Step 1: the anchor node of each location aware sends the location beacon signal by the constant power periodic broadcast;

Step 2: described node to be measured receives above-mentioned location beacon signal, treat described node to be measured obtain one group of complete location from same anchor node with beacon signal after, one group of complete location receiving is sent to described gateway anchor node with the received signal intensity level of beacon signal;

Step 3: described gateway anchor node sends to the described backstage centre of location with the received signal intensity level of node to be measured and the strength of transmitted signals value of described anchor node;

Step 4: the described backstage centre of location calculates described node to be measured to the distance between the described anchor node according to the difference between strength of transmitted signals value and the received signal intensity level;

Step 5: the described backstage centre of location is calculated to the position coordinates of the distance between each anchor node to described survey node according to described node to be measured.

Calculate the distance between node to be measured and the anchor node in the above-mentioned steps four by the following method:

(1), getting apart from the distance of location aware anchor node is d ₀Reference mode, d wherein ₀Be known constant, and measure the received signal intensity level of this reference mode that the received signal intensity level that deducts this reference mode with the transmit signal strength value of anchor node obtains the transmission path loss of reference point, with L (d ₀) expression;

(2), the strength of transmitted signals value of described anchor node is deducted the received signal intensity level of described node to be measured, its signal strength difference is with L (d) expression;

(3), calculate the distance of described node to be measured between the described anchor node, represent with d:

$d=a^{\frac{L\left(d_0\right)-X_{\mathrm{\σ}}-L\left(d\right)}{b\×n}}\×d_0$

Wherein, a is a constant, and its span is 10 ± 2, X _σFor standard deviation is the normal random variable of σ, b is a constant, and its span is 10 ± 2, and n is a path loss index.

The position coordinates of node to be measured described in the above-mentioned steps five is by obtaining by the ChanShi algorithm: use

The position coordinates of representing node to be measured is used

The position coordinates of expression gateway anchor node is used The position coordinates of representing two other anchor node:

$\left[\begin{array}{c}x\\ y\end{array}\right]={\left[\begin{array}{cc}{x}_2-x_1& y_2-y_1\\ x_3-x_1& y_3-y_1\end{array}\right]}^{-1}*\{\left[\begin{array}{c}{d}_2-d_1\\ d_3-d_1\end{array}\right]d_1+\frac{1}{2}\left[\begin{array}{c}{(d_2-d_1)}^2-({x_2}^2+{y_2}^2)+({x_1}^2+{y_1}^2)\\ {(d_3-d_1)}^2-({x_3}^2+{y_3}^2)+({x_1}^2+{y_1}^2)\end{array}\right]\}$

Wherein, d ₁Represent that node to be measured is to the distance between the gateway anchor node, d ₂, d ₃Represent that node to be measured is to the distance between two other anchor node.

Compared with prior art, the invention has the advantages that: according to the difference of anchor node strength of transmitted signals and node received signal intensity to be measured, calculate node to be measured to the distance between the described anchor node, utilize node to be measured to the implementation method of coming the position coordinates to node to be measured to position apart from difference between each anchor node then, can effectively reduce positioning error, especially relevant multipath disturbs the error that causes, improves bearing accuracy.

Description of drawings

Fig. 1 is a wireless sensor network node structural representation in the embodiment of the invention;

Fig. 2 is the process flow diagram of wireless sensor network node locating method in the embodiment of the invention;

Embodiment

Embodiment describes in further detail the present invention below in conjunction with accompanying drawing.

Wireless sensor network is made up of the sensor node SN to be measured of many unknown positions and stochastic distribution and the anchor node AN of three known location at least, and wherein certain anchor node can serve as gateway node and communicates by letter with the backstage centre of location.In the present embodiment, three anchor node AN1, AN2, AN3 are arranged, its position coordinates is known, and anchor node AN1 communicates by letter with the backstage centre of location as the gateway anchor node, and its coordinate is The coordinate of anchor node AN2 is

The coordinate of anchor node AN3 is

Position the unknown of node SNn to be measured is seen shown in Figure 1 in detail.

As Fig. 2, the invention provides three anchor node AN1 that wireless sensor network node locating method starts from area arrangements location aware to be measured, AN2, AN3, getting anchor node AN1 is the gateway anchor node, three anchor node AN1 then, AN2, AN3 sends the location beacon signal according to the constant power periodic broadcast, node to be measured receives the location beacon signal of anchor node, when node to be measured obtain one group of complete location from same anchor node with beacon signal after, one group of complete location receiving is sent to gateway anchor node AN1 with the received signal intensity level of beacon signal, gateway anchor node AN1 sends to the described backstage centre of location with the received signal intensity level of node to be measured and the strength of transmitted signals value of described anchor node, the backstage centre of location calculates node branch to be measured according to the difference between strength of transmitted signals value and the received signal intensity level and is clipped to three anchor node AN1, AN2, between the AN3 apart from d1, d2, d3, the backstage centre of location is according to node to three a to be measured anchor node AN1 then, AN2, distance between the AN3 is calculated the position coordinates of surveying node.

The star that the above-mentioned backstage centre of location is calculated between node SNn to be measured and three anchor node AN1, AN2, the AN3 in the following manner is huge from d1, d2, d3:

(1), gets apart from the distance of three anchor node AN1, AN2, AN3 and be d ₀Three reference modes, wherein d ₀Be known constant, and measure the received signal intensity level of these three reference modes, the received signal intensity level that deducts above-mentioned three reference modes respectively with the transmit signal strength value of three anchor node AN1, AN2, AN3 obtains the transmission path loss of three reference point, uses L (d respectively ₀) 1, L (d ₀) 2, L (d ₀) 3 expressions;

(2), the strength of transmitted signals value with anchor node AN1 deducts the received signal intensity level that node to be measured receives the location usefulness beacon signal of anchor node AN1 respectively, L (d) 1 expression of its signal strength difference; The strength of transmitted signals value of anchor node AN2 is deducted the received signal intensity level that node to be measured receives the location usefulness beacon signal of anchor node AN2 respectively, and its signal strength difference is represented with L (d) 2; The strength of transmitted signals value of anchor node AN3 is deducted the received signal intensity level that node to be measured receives the location usefulness beacon signal of anchor node AN3 respectively, and its signal strength difference is represented with L (d) 3;

(3), calculate distance between node to three to be measured anchor node AN1, AN2, the AN3:

$d_1=a^{\frac{L\left(d_0\right)1-X_{\mathrm{\σ}}-L\left(d\right)1}{b\×n}}\×d_0,$

$d_2=a^{\frac{L\left(d_0\right)2-X_{\mathrm{\σ}}-L\left(d\right)2}{b\×n}}\×d_0,$

$d_3=a^{\frac{L\left(d_0\right)3-X_{\mathrm{\σ}}-L\left(d\right)3}{b\×n}}\×d_0$

Wherein, a is a constant, and its span is 10 ± 2, x _σFor standard deviation is the normal random variable of σ, b is a constant, and its span is 10 ± 2, and n is a path loss index.

The above-mentioned backstage centre of location is according to the position coordinates by ChanShi algorithm computation node to be measured

$\left[\begin{array}{c}x\\ y\end{array}\right]={\left[\begin{array}{cc}{x}_2-x_1& y_2-y_1\\ x_3-x_1& y_3-y_1\end{array}\right]}^{-1}*\{\left[\begin{array}{c}{d}_2-d_1\\ d_3-d_1\end{array}\right]d_1+\frac{1}{2}\left[\begin{array}{c}{(d_2-d_1)}^2-({x_2}^2+{y_2}^2)+({x_1}^2+{y_1}^2)\\ {(d_3-d_1)}^2-({x_3}^2+{y_3}^2)+({x_1}^2+{y_1}^2)\end{array}\right]\}$

Claims (3)

1. One kind based on the range finding wireless sensor network node locating method, the anchor node that comprises at least three location awares, the node to be measured of position the unknown and the backstage centre of location, have at least an anchor node to link to each other with the backstage centre of location by network as the gateway anchor node at least in the anchor node of described three location awares, it is characterized in that: described wireless sensor network node locating method is realized by following steps:

   Step 1: described each anchor node sends the location beacon signal by the constant power periodic broadcast;

   Step 2: described node to be measured receives above-mentioned location beacon signal, treat described node to be measured obtain one group of complete location from same anchor node with beacon signal after, one group of complete location receiving is sent to described gateway anchor node with the received signal intensity level of beacon signal;

   Step 3: described gateway anchor node sends to the described backstage centre of location with the received signal intensity level of node to be measured and the strength of transmitted signals value of described anchor node;

   Step 4: the described backstage centre of location calculates described node to be measured to the distance between the described anchor node according to the difference between strength of transmitted signals value and the received signal intensity level;

   Step 5: the described backstage centre of location is calculated to the position coordinates of the distance between each anchor node to described survey node according to described node to be measured.
2. 2. the wireless sensor network node locating method based on range finding according to claim 1, it is characterized in that: the backstage centre of location is calculated the distance between node to be measured and the anchor node by the following method in the described step 4:

   (1), getting apart from the distance of location aware anchor node is d ₀Reference mode, d wherein ₀Be known constant, and measure the received signal intensity level of this reference mode that the received signal intensity level that deducts this reference mode with the transmit signal strength value of anchor node obtains the transmission path loss of reference point, with L (d ₀) expression;

   (2), the strength of transmitted signals value of described anchor node is deducted the received signal intensity level of described node to be measured, its signal strength difference is with L (d) expression;

   (3), calculate the distance of described node to be measured between the described anchor node, represent with d:

   $d=a^{\frac{L\left(d_0\right)-X_{\mathrm{\σ}}-L\left(d\right)}{b\×n}}\×d_0$

   Wherein, a is a constant, and its span is 10 ± 2, X _σFor standard deviation is the normal random variable of σ, b is a constant, and its span is 10 ± 2, and n is a path loss index.
3. 3. the wireless sensor network node locating method based on range finding according to claim 1 is characterized in that: the position coordinates of surveying node described in the described step 5 obtains by the ChanShi algorithm: use

   

   The position coordinates of node is surveyed in expression, uses

   

   The position coordinates of expression gateway anchor node is used

   

   

   The position coordinates of representing two other anchor node:

   $\left[\begin{array}{c}x\\ y\end{array}\right]={\left[\begin{array}{cc}{x}_2-x_1& y_2-y_1\\ x_3-x_1& y_3-y_1\end{array}\right]}^{-1}*\{\left[\begin{array}{c}{d}_2-d_1\\ d_3-d_1\end{array}\right]d_1+\frac{1}{2}\left[\begin{array}{c}{(d_2-d_1)}^2-({x_2}^2+{y_2}^2)+({x_1}^2+{y_1}^2)\\ {(d_3-d_1)}^2-({x_3}^2+{y_3}^2)+({x_1}^2+{y_1}^2)\end{array}\right]\}$

   Wherein, d ₁Represent that node to be measured is to the distance between the gateway anchor node, d ₂, d ₃Represent that node to be measured is to the distance between two other anchor node.

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