CN101778472A - Distributed panel-point positioning method for wireless sensor network - Google Patents

Abstract

The invention relates to a distributed panel-point positioning method for a wireless sensor network, belonging to the technical field of the panel-point self-positioning in the wireless sensor network. Aiming at the characteristic of the DV-Distance positioning algorithmic in the wireless sensor network, the invention provides an improved DV-Distance panel-point positioning method, particularly a skip counting from an anchor panel point to an unknown panel point is led into a distance corrected value; and based on the technical scheme, a distance corrected method is provided, and the near-far relation between the unknown panel point and the anchor panel point is considered, and the identical rout problem is considered too. Compared with the original arithmetic, under the condition of not increasing the extra hardware cost of the panel point and increasing a little of the working capacity of the arithmetic calculation, the invention has higher positioning precision, and is suitable for the sensor network system with the self-organization characteristic.

Description

A kind of distributed panel-point positioning method of wireless sensor network

Technical field

The present invention relates to a kind of distributed panel-point positioning method of wireless sensor network, concrete being applicable to has the sensor network system of self-organizing feature, belongs to the node self poisoning field of wireless sensor network.

Background technology

Wireless sensor network is listed in first of ten kinds of change future world emerging technologies by " MIT technology review ", U.S. Business Week prediction WSN will start new industry tide in the near future, the survey report of Future in China prediction in 20 years technology, have in the message area technical task 7 directly related with WSN, " the national medium-term and long-term science and technology development planning outline " of issue in 2006 determined three forward position directions for information technology, wherein two researchs with WSN are directly related, be intelligent perception technology and self-organization network technology, have wide market application prospect.

In wireless sensor network, the perception information of collection only knows that coordinate position just has actual application value, so the node locating problem becomes one of key technology.According to location mechanism, wireless sensor network self poisoning algorithm is divided into two classes: based on range finding location algorithm and non-distance measuring location algorithm, the former need be by the range information of point-to-point between some ranging technology measured node; The latter need not range information, only uses the self-position of internodal estimated distance computing node.Location algorithm location mechanism based on range finding has proposed higher requirement to the hardware facility of network, and this class algorithm all will produce a large amount of calculating and communication overhead when obtaining relatively accurately positioning result.Distance-finding method commonly used has RSSI, TOA, TDOA and AOA.Though RSSI meets low-power, requirement cheaply, might produce ± 50% range error; TOA needs between node precise time synchronous, can't be used for loose coupling type location; The TDOA technology is subject to the influence that ultrasonic wave propagation distance finite sum NLOS problem is propagated ultrasonic signal; AOA also is affected by the external environment, and needs additional hardware, possibly can't be used for sensor node on hardware size and power consumption; The location algorithm of non-distance measuring has centroid algorithm, the convex programming algorithm, and typical algorithm such as DV-hop are because low-cost, relative positioning precision height have been obtained extensive use.But centroid algorithm requires beaconing nodes density to want high, and becomes the distributed in grid of rule, otherwise position error is bigger.

DV-distance algorithm computation node to be positioned is to replace air line distance with minute segment distance sum to the distance of anchor node, be applicable to the isotropism network, under the intensive inadequately situation of network, location node increases to the jumping figure of anchor node, and the error of fold line distance and air line distance obviously increases; Secondly, each node has the broken line information that records each anchor node in the network, have the ability that calculates the anchor node jumping figure simultaneously, and the DV-Distance algorithm does not utilize jumping figure information to retrain apart from correction value; And do not consider the conforming problem of some node path in the network.

Summary of the invention

For solving the problems referred to above that exist in the existing method and technology, the invention provides a kind of distributed panel-point positioning method of wireless sensor network, this improves the DV-Distance algorithm when calculating unknown node to each anchor node corrected range, if this anchor node is nearest apart from unknown node, adopt still when calculating corrected range that the method for flooding originally obtains apart from correction value; Otherwise, with regard to the correction value of the nearest anchor node of this unknown node of service range to other anchor node, replace this unknown node to other anchor node apart from correction value; Simultaneously, improve algorithm and considered the close and distant relation between unknown node and the anchor node and the consistency of path problem of existence.

The technical solution adopted in the present invention is as follows: the distributed panel-point positioning method of this wireless sensor network comprises following steps:

Step 1: by class distance vector method for routing, each anchor node in the wireless sensor network obtains other anchor node ID, position coordinates, fold line distance and jumping figure, unknown node is only stored anchor node ID, position coordinates, fold line distance and the jumping figure of the own arest neighbors of distance, and the quantity of these anchor nodes is in threshold values;

Step 2: according to the information that step 1 is obtained, each anchor node calculate it to other anchor node apart from correction value, for replying node, what reply node is nearest correction value apart from correction value apart from its nearest anchor node; Then, include the message bag of nearest correction value by the normal direction Web broadcast that floods, this message bag is the handshake information bag;

Step 3: unknown node receives the handshake information bag, parses the nearest correction value in the step 2, as this unknown node to reply node apart from correction value; Then, unknown node sends to the anchor node ID that stores and replys node;

Step 4: reply node and send the anchor node of its arest neighbors apart from correction value to unknown node;

Step 5: according to step 3, step 4 receive apart from correction value, unknown node is calculated the own corrected range that arrives anchor node;

Step 6: the corrected range that root a tree name trilateration principle and step 5 obtain, the position coordinates of calculating unknown node.

Each anchor node of calculating described in the step 2 to the formula apart from correction value of other anchor nodes is:

${\mathrm{Correction}}_{i.j}=\frac{({\mathrm{Dis}}_{i.j}-{\mathrm{dis}}_{i.j})/{\mathrm{Hop}}_{i.j}}{{\mathrm{Dis}}_{i.j}},$ In the formula: dis _I.jThe anchor node that for ID is i is the fold line distance of the anchor node of j to ID, Dis _I.jBe anchor node i, the air line distance between j; Hop _I.jBe anchor node i, the accumulative total jumping figure between j, Correction _I.jBe the distance correction value.

Calculating unknown node described in the step 6 to the corrected range formula of anchor node is:

${\mathrm{DisCorr}}_{k.i}=\frac{{\mathrm{dis}}_{k.\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="HSA00000047141700021.png,HSA00000047141700041.png"\; state="\{\{state\}\}">j</figure-callout>}}}{1+{\mathrm{Correction}}_{k.i}\&times;{\mathrm{Hop}}_{k.i}},$ In the formula: dis _K.jThe unknown node that for ID is k is the fold line distance of the anchor node of i to ID, Correction _K.iFor k unknown node of distance between i anchor node apart from correction value; Hop _K.iFor unknown node k to the accumulative total jumping figure between anchor node i, DisCorr _K.iFor unknown node k to the revised distance of anchor node i.

The distributed panel-point positioning method of wireless sensor network provided by the invention under additional hardware cost that does not increase node and algorithm computation workload increase situation a little, is compared with former algorithm and to be had higher positioning accuracy.

Description of drawings

Fig. 1 is a flow chart of the present invention;

Fig. 2 is embodiments of the invention figure;

Fig. 3 is a position error comparison diagram of the present invention;

Average position error comparison diagram when Fig. 4 is a unknown node number change of the present invention;

Average position error comparison diagram when Fig. 5 is an anchor node number change of the present invention.

Embodiment

The present invention is further described below in conjunction with accompanying drawing.

The distributed panel-point positioning method of wireless sensor network provided by the invention comprises following steps (shown in Figure 1):

Step 1: by class distance vector method for routing, each anchor node in the wireless sensor network obtains other anchor node ID, position coordinates, fold line distance and jumping figure; Unknown node is only stored anchor node ID, position coordinates, fold line distance and the jumping figure of the distance own arest neighbors of quantity in threshold values of anchor node.In conjunction with the enforcement illustration of Fig. 2, calculate unknown node u0 coordinate.Suppose that nearest and anchor node in threshold values is b1～b4 apart from unknown node u0, table 1 is the fold line distance and the jumping figure of anchor node b2 and other anchor node, bij asks unknown node u0 and each anchor node fold line distance and jumping figure to anchor node j table 2 for waiting for anchor node i in the table, and uij asks unknown node i to anchor node j for waiting in the table.

Table 1 b2 is to other anchor node fold line distance

B2 is to other anchor node	Fold line distance	Jumping figure
			??b2.1	??1+2+1.5＝4.5	??3
??b2.3	??1+1+1.5+2＝5.5	??4
			??b2.4	??1+1+2+2＝6	??4

Table 2 u0 is to each anchor node fold line distance

U0 is to each anchor node	Fold line distance	Jumping figure
			??u0.1	??2+2＝4	??2
??u0.2	??1＝1	??1
			??u0.3	??1+1.5+2＝4.5	??3
??u0.4	??1+2+2＝5	??3

Step 2: according to the information that step 1 is obtained, calculate each anchor node to other anchor node apart from correction value, deposit in the correction value chained list of oneself, apart from the computing formula of correction value be:

${\mathrm{Correction}}_{i,j}=\frac{({\mathrm{Dis}}_{i.j}-{\mathrm{dis}}_{i.j})/{\mathrm{Hop}}_{i,j}}{\&times;{\mathrm{Dis}}_{i.j}}$

In the formula: dis _I.jThe anchor node that for ID is i is the fold line distance of the anchor node of j to ID, Dis _I.jBe anchor node i, the air line distance between j; Hop _I.jBe anchor node i, the accumulative total jumping figure between j, Correctioni.j are apart from correction value.For example, ask b2 to the b1 anchor node apart from correction value the time calculate:

Table 3 for b2 to each anchor node apart from correction value.

Table 3 b2 to each anchor node apart from correction value

B2 is to other anchor node	Fold line distance	Air line distance	Jumping figure	Correction value
					??b2.1	??4.5	??4	??3	??1/24
??b2.3	??5.5	??5	??4	??1/40
					??b2.4	??6	??5.5	??4	??1/44

As shown in Table 2, u0 is nearest apart from anchor node b2, and b2 is for replying node, therefore u0 takes the optimum distance correction value that b2 obtains, promptly u0 to b2 be 1/24 apart from correction value, then, include the message bag of optimum distance correction value by the normal direction Web broadcast that floods, this message bag is the handshake information bag.

Step 3; Unknown node receives the handshake information bag by the controlled routing method that floods, and parses the optimum distance correction value in the step 2, as this unknown node to reply node apart from correction value, promptly b2.1's is 1/24 apart from correction value; Then, unknown node sends to the anchor node ID that stores and replys node.The ID that will send in this example is 2,3,4.

Step 4: reply node and send the anchor node of its arest neighbors apart from correction value to unknown node.

Step 5: unknown node according to step 3, step 4 receive apart from correction value, as shown in table 4.

The table 4u0 to each anchor node apart from correction value

U0 is to node	Correction value
		??u0.1	??1/24
??u0.2	??1/24
		??u0.3	??1/40
??u0.4	??1/44

Calculate the corrected range of unknown node to anchor node, its formula is:

${\mathrm{DisCorr}}_{k,i}=\frac{{\mathrm{dis}}_{k.\mathrm{<figure-callout\; id="1"\; label="j"\; filenames="HSA00000047141700021.png,HSA00000047141700041.png"\; state="\{\{state\}\}">j</figure-callout>}}}{1+{\mathrm{Correction}}_{k.i}\&times;{\mathrm{Hop}}_{k.i}}$

In the formula: dis _K.iThe unknown node that for ID is k is the fold line distance of the anchor node of i to ID, Correction _K.iFor k unknown node of distance between i anchor node apart from correction value; Hop _K.iFor unknown node k to the accumulative total jumping figure between anchor node i, DisCorr _K.iFor unknown node k to the revised distance of anchor node i.For example, u0 calculates to the adjusted range of b1

Table 5 arrives the revised distance of each anchor node for node u0.

Table 5 u0 is to the revised distance of each anchor node

U0 is to node	Fold line distance	Jumping figure	Corrected range
				??u0.1	??4	??2	??3.69

U0 is to node	Fold line distance	Jumping figure	Corrected range
				??u0.2	??1	??1	??0.96
??u0.3	??4.5	??3	??4.18
				??u0.4	??5	??3	??4.68

Step 6: the corrected range that root a tree name trilateration principle and step 5 obtain, the position coordinates of calculating unknown node.

In order to assess availability of the present invention and validity, this algorithm has been carried out emulation.Experiment condition is evenly distribute at random in 100*100 square metre the square area anchor node and the unknown node of some, and node adopts radio ideal propagation model; Node communication radius maximum is made as R=20 rice.

Establishing the anchor node number in the experiment 1 is 5, and the unknown node number is 50.Positioning accuracy contrasts as shown in Figure 3, and wherein transverse axis is represented the unknown node number, and the longitudinal axis is represented position error.The average position error of DV-Distance is 3.0554R, and the average position error of the algorithm after the improvement is 0.7916R, and the result shows that this algorithm has improved positioning accuracy.

The number of establishing anchor node in the experiment 2 is 5, and the unknown node number is increased to 550 from 50.Average positioning accuracy contrast as shown in Figure 4, as can be known from Fig. 4: along with the increase of network node density, positioning accuracy improves, this is owing to the quantity along with unknown node increases, node layout is homogenizing more, unknown node more can find the broken line of near linear to anchor node, so position error reduces.When unknown node quantity reaches 200 when above, to compare with former algorithm, the positioning accuracy of improving algorithm has improved about 20%.

Establishing the unknown node number in the experiment 3 is 100, and the anchor node number is increased to 23 from 3.As can be known from Fig. 5: with the increase of anchor node quantity, two kinds of algorithms have all improved positioning accuracy, and the ratio that improves is approximate identical.Reason is that node has range capability, and algorithm is strong to the density and the topological structure dependence of network node, increases a spot of anchor node, and is little to the influence of network node density and topological structure generation, so the ratio that positioning accuracy improves is constant substantially.

Claims (3)

1. the distributed panel-point positioning method of a wireless sensor network is characterized in that comprising following steps:

Step 1: by class distance vector method for routing, each anchor node in the wireless sensor network obtains other anchor node ID, position coordinates, fold line distance and jumping figure, unknown node is only stored anchor node ID, position coordinates, fold line distance and the jumping figure of the own arest neighbors of distance, and the quantity of these anchor nodes is in threshold values;

Step 2: according to the information that step 1 is obtained, each anchor node calculate it to other anchor node apart from correction value, for replying node, what reply node is the optimum distance correction value apart from correction value apart from its nearest anchor node; Then, include the message bag of optimum distance correction value by the normal direction Web broadcast that floods, this message bag is the handshake information bag;

Step 3: unknown node receives the handshake information bag, parses the optimum distance correction value in the step 2, as this unknown node to reply node apart from correction value; Then, unknown node sends to the anchor node ID that stores and replys node;

Step 4: reply node and send the anchor node of its arest neighbors apart from correction value to unknown node;

Step 5: according to step 3, step 4 receive apart from correction value, unknown node is calculated the own corrected range that arrives anchor node;

Step 6: the corrected range that root a tree name trilateration principle and step 5 obtain, the position coordinates of calculating unknown node.

2. the distributed panel-point positioning method of wireless sensor network according to claim 1 is characterized in that: calculating each anchor node in the step 2 to other anchor node apart from the correction value formula is:

${\mathrm{Correction}}_{i.j}=\frac{({\mathrm{Dis}}_{i.j}-{\mathrm{dis}}_{i.j})/{\mathrm{Hop}}_{i.j}}{{\mathrm{Dis}}_{i.j}}$

In the formula: dis _I.jThe anchor node that for ID is i is the fold line distance of the anchor node of j to ID, Dis _I.jBe anchor node i, the air line distance between j; Hop _I.jBe anchor node i, the accumulative total jumping figure between j, Correction _I.jBe the distance correction value.

3. the distributed panel-point positioning method of wireless sensor network according to claim 1 is characterized in that: calculating unknown node in the step 5 to the corrected range formula of anchor node is:

${\mathrm{DisCorr}}_{k.i}=\frac{{\mathrm{dis}}_{k.j}}{1+{\mathrm{Correction}}_{k.i}\&times;{\mathrm{Hop}}_{k.i}}$

In the formula: dis _K.iThe unknown node that for ID is k is the fold line distance of the anchor node of i to ID, Correction _{K, i}For k unknown node of distance between i anchor node apart from correction value; Hop _{K, i}For unknown node k to the accumulative total jumping figure between anchor node i, DisCorr _K.iFor unknown node k to the revised distance of anchor node i.

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