CN101409940B - Route selection method for wireless sensor network facing to target tracking application - Google Patents

Abstract

The invention relates to a target tracking application-oriented wireless sensor network routing method. The method comprises the following steps: adopting a forwarding strategy which combines greedy forwarding based on a target active area with bounded flooding if the data packet to be forwarded is a query data packet from a sink node to a target area; and adopting the forwarding strategy which combines the greedy forwarding based on a sink node position with supply energy of the node if the data packet to be forwarded is an aggregate data packet from the target area to the sink node. In the method, the node just needs to maintain self state information, which causes the method to be capable of better adapting to situations when the number of the nodes increases; the greedy forwarding strategy based on geographic information is adopted to reduce delay time of the data packet routing by reducing communication hops; and when the aggregate data packet is forwarded, a generalized function of the energy and distance of the nodes is taken as a forwarding cost to cause the aggregate data packet to be forwarded to a target node as soon as possible and balance energy consumption of all nodes, thus prolonging the service life of the network.

Description

The route selection method for wireless sensor network that object-oriented tracking is used

Technical field

The invention belongs to the wireless self-organization network field, particularly a kind of route selection method for wireless sensor network of using based on the object-oriented tracking of geography information.

Background technology

WSN is that the microsensor node by a large amount of autonomies makes up in modes such as Ad-Hoc and forms, and can carry out the network of perception synergistically to certain physical phenomenon.Because having, this network do not need the infrastructure of fixing, can dispose fast, characteristics such as disguised, self-organization and robustness, in numerous occasions such as military affairs, industry, traffic, safety, medical treatment and families important use potentiality and prospect being arranged, is one of hot spot technology of industrial quarters and academia research both at home and abroad at present.

The power supply energy that node carries among the WSN is limited; Individual node communication, calculating and storage capacity a little less than; The topology of networks dynamic change; With to use correlation stronger etc.These characteristics require the method for routing among the WSN must adapt to own characteristic, and design at specifically being used for.

The WSN method for routing that is applied to the target following application should satisfy following demand: (1) energy consumption is low.Each sensor node uses finite capacity usually in the network, non-exchange battery, and therefore, method for routing must be taked Energy Saving Strategy during target following was used.(2) transfer of data is reliable.Target following has higher requirements for the reliable transmission of route data, because if route data is lost, may cause the inaccurate of tracking or lose, can consume more system capacity and reinstate Restoration Mechanism behind the track rejection, therefore, the method for routing that is applied to target following must transmit data reliably.(3) agreement can be expanded.The sensor node quantity that target following is adopted may be along with the quantity of target, and the precision of tracking etc. require constantly to increase, and therefore, target following application requirements method for routing has extensibility preferably.In order to adapt to the network configuration of topological dynamic change, improve the robustness of system, method for routing should adopt distributed operational mode.(4) real-time communication is good.In target speed occasion faster, follow the tracks of accurately target, data communication has certain real-time requirement between node.Otherwise just can't realize target is carried out in time, followed the tracks of exactly.

The researcher has proposed many WSN method for routing.According to whether coming recognition purpose ground with the geographical position, whether route utilizes geographical location information in calculating, and these method for routing can be divided into based on the method for routing of geography information and non-method for routing two big classes based on geography information.In target following is used, often need to wake up the nearest sensor node of distance objective, to obtain relevant informations such as more accurate position about target, with the geographical position of node foundation as Route Selection, routing function not only can be finished, the energy consumption that system safeguards Routing Protocol specially can also be reduced.Therefore, the method for routing based on geography information is suitable for WSN target following application.The problem that employing need solve based on the method for routing of geography information is communication " cavity " problem, and promptly packet is when fixed route is transmitted, and some nodes are because the frequent packet of transmitting causes energy depletion to lose efficacy, thereby form forwarding " cavity ".In the method for routing that has proposed based on geography information, GPSR (GreedyPerimeter Stateless Routing, GPSR) [Karp Band Kung HT. " GPSR:Greedy perimeter stateless routing for wireless networks " .Proceeding of the6th annual internat ional conference on Mobilecomput ing and networking, New York:ACM Press, 2000,243-254] use greedy forwarding and transmit two kinds of methods forwarding packets along circumference.Greedy retransmission method is a basic scheme, when greedy algorithm lost efficacy, GPSR solves the problem in " cavity " by the method for setting up plane graph (such as adding Berli figure) on the primitive network figure of this zone, promptly, recover greedy when condition satisfies again and transmit by coming restoration route to the mode of target area continuation forwarding packet around the plane graph border.So repeatedly, to the last arrive the destination.

GEAR (Geographical and Energy-Aware Rout ing, GEAR) [Yu Y, Estrin D, and Govindan R. " Geographical and Energy-Aware Routing:A Recursive Data Dissemination Protocol for Wireless SensorNetworks " .UCLA Computer Science Department Technical Report, UCLA-CSD TR-01-0023,2001.] agreement utilizes node energy and geography information to transmit data as heuristic selection path to the target area.One of each node maintenance of GEAR protocol requirement is estimated expense and a study costs that arrives destination node by neighbor node.The expense of estimating is a residue energy of node and integrate-cost to the destination node distance, and study costs then is to describing the needed improvement of estimating expense when having the cavity in the network.If there is the communication cavity, then adopt study costs to replace estimating expense.

More than be applied to target following based on the method for routing of geography information and have the following disadvantages:

(1) method in GPSR solution communication cavity is to transmit along circumference, need generate plane graph according to the primitive network topological diagram, computation complexity is higher, and packet is constantly along transmitting than the sparse a lot of plane graph border of primitive network figure, cause node on the plane graph soon because of energy consumption totally lost efficacy easily, cause network division.

(2) node load that some expenses are little among the GEAR is big, thereby is easy to cause such node energy approach exhaustion and lost efficacy; Handle that residue energy of node information and study cost information all need to upgrade transmission in the communication cavity, this will increase Internet traffic, and the time interval length that these information are upgraded also can have influence on the performance of algorithm simultaneously.

(3) GPSR and GEAR all do not consider the real-time requirement that packet is transmitted under the target following application background.When running into the communication cavity, GPSR need expend the big time and calculation cost carries out plane map generalization work; GEAR also needs repeatedly to communicate by letter between node to transmit energy and range information, with balancing network energy consumption and greedy the forwarding.But in target following is used, when running into the communication cavity, the most important thing is to accomplish as far as possible promptly to get around on the time cavity, reducing internodal communication delay, thereby reduce whole network end-to-end communication delay.

(4) GSPR and GEAR algorithm are not all considered the energy consumption problem of node under different conditions.

Summary of the invention

The objective of the invention is to satisfy the performance requirement that target following is applied in aspects such as energy efficiency, reliability, real-time and extensibility at existing WSN Routing Protocol, wireless sensor network (wireless sensor network, WSN) route selection method that a kind of object-oriented tracking is used are proposed.

To achieve these goals, the present invention is made up of two parts:

(1) the sink node to the data query package transmitting method QPR of target (Query PacketsRouting, QPR): adopt the greediness of based target zone of action to transmit and the limited forwarding strategy that floods and combine;

(2) target to the sink node converge data packet greedy retransmission method APR (AggregatePackets Routing, APR): adopt the forwarding strategy that greediness is transmitted and residue energy of node combines based on the sink node location.

The concrete steps of said method are::

Step 1: carry out the netinit process, obtain neighbor information by information exchange between node, and in routing table, preserve a hop neighbor information;

Step 2: after node is received packet, at first by destination node ID judge this packet be the data query bag that sends by the sink node or send from the target area converge packet;

Step 3: if the data query bag, then execution in step 4; Otherwise execution in step 5;

Step 4: start the data query package transmitting method of sink node to target;

Step 41: transmit the limited regional LFZ that floods (limited flooding zone) that determines present node with the limited principle that combines of flooding according to greediness;

Step 42: judge whether LFZ is empty set, if be empty set then execution in step 421, otherwise execution in step 423;

Step 421: the cavity exists, and relaxes the limited condition that floods, and redefines the LFZ (relaxed LFZ, lax LFZ) of node;

Step 422: by the lax LFZ data query bag that floods;

Step 423: by the LFZ data query bag that floods;

Step 5: start target and converge the data packet greedy retransmission method to the sink node;

Step 51:, find out node with minimum cost according to the estimation cost of the principle calculating neighbor node that greediness is transmitted and dump energy combines;

Step 52: whether the minimum cost of judging this node is less than the estimation cost of present node, if be not less than, then execution in step 521, otherwise execution in step 524;

Step 521: have the cavity, relax greedy forwarding condition, reselect next-hop node;

Step 522: if selected node is a last hop node of present node just, illustrate to have the route endless loop, change step 523, otherwise change step 524;

Step 523: start slow astern and jump the mechanism of rerouting, present node notifies its upstream node to reselect next-hop node, and does not consider oneself when selecting, and upstream node changes step 51;

Step 524: this node is as the next-hop node of present node;

Step 525: present node is transmitted and is converged packet.

The present invention has taken into full account target following and has used WSN Routing Protocol specific performance properties demand, and its advantage and beneficial effect mainly are:

(1) method that is proposed has energy service efficiency preferably, is mainly reflected in by reducing the node number that participates in transmitting as far as possible to have reduced the network energy consumption.As, adopt the limited strategy minimizing that forwarding combines with greediness that floods to participate in the forward node number in the data query package transmitting method; Converge the each node that only need be transmitted in the hop neighbor of data packet forwarding method middle and upper reaches node, and this forwarding also is " greediness ".Converge the equilibrium of also having considered energy in the data packet forwarding method and use, help prolonging network life.

(2) method that is proposed is simple, node does not need to keep too much routing iinformation, only need to preserve the positional information of a hop neighbor node, without any need for global information, can carry out with distributed way, node can arbitrarily increase, and can better adapt to the variation of network topology structure, and extensibility is better.

(3) method that is proposed adopts the greedy forwarding strategy based on geography information, and packet always along transmitting near the direction of target, can reduce the communication jumping figure between the data packet transceive side like this, thereby reduces end-to-end time delay.

Description of drawings

Fig. 1 is a packet forward-path system of selection flow chart of the present invention.

Fig. 2 is the limited area schematic that floods of sink node of the present invention.

V among the figure _MinAnd v _MaxMinimum and the maximal rate of representing target respectively, the 0th, target is in t position constantly, and then (T〉t) target zone that may exist is for 0 to be the center of circle constantly for T, and interior ring radius is v _Min* (T-t+ δ), outer shroud radius are v _Max* the circle ring area of (T-t+ δ), wherein δ is the communication delay of sink node to the target area.The black round dot is represented node, and the contained node of dash area is the limited zone that floods of sink node.

Fig. 3 is a data query bag routing policy schematic diagram of the present invention

The black dot is represented node among the figure, and the black large circle point is represented sink node and center, target area.

Fig. 4 converges packet routing policy schematic diagram for the present invention

Wherein the black dot is represented node, and the black large circle point is represented the sink node.

Embodiment

The present invention is described in further detail below in conjunction with drawings and Examples.

The present invention carries out an initialization procedure before network is set up, each node obtains a hop neighbor information by information exchange and is kept in the routing table; By the self-align algorithm of existing various nodes, node obtains the geographical position of oneself.

The data query packet format is: [ID _Qrp, v ^(pri), QryData], comprising data query bag ID ID _Qrp, last node v ^(pri), t is the target initial estimated location constantly

, and the content QryData of inquiry;

Converging data packet format is: [ID _ARP, v ^(cur), X _s, ObjData], comprising converging packet ID ID _ARP, current processing node v ^(cur), sink node coordinate X _sWith the dbjective state data ObjData that detects;

In the packet repeating process, after certain node is received packet, at first by destination node ID judge this packet be the data query bag that sends by the sink node or send from the target area converge packet;

Embodiment 1:

Referring to Fig. 2 present embodiment is described.Present node v ^(cur)What receive is that the data query bag (contains ID _Qrp), v ^(cur)Take a kind of greedy forwarding to transmit packet, determine a hop neighbor node set (being called LFZ (limitedflooding zone)) that will flood according to formula (1) with the limited strategy that combines that floods:

LFZ(v ^(cur))＝{V ^(j)|v ^(j)∈LFZ(sink)}∩{v ^(k)|v ^(k)∈nbr(v ^(cur))

(1)

And | X _κ-X _o|≤| X _v ^Cur-X _o|

Nbr (v wherein ^(cur)) be v ^(cur)A hop neighbor node set, X _v ^CurAnd X _oThe geographical position of representing present node and center, target area respectively, | X _k-X _o| and | X _v ^Cur-X _o| represent a certain node v respectively ^(cur)A certain neighbor node v ^(k)And v ^(cur)Euclidean distance with the center, target area;

From formula (1) as can be seen, for dwindling the zone that floods of present node, v ^(cur)Downstream node should meet the following conditions simultaneously: (1) is among the LFZ of sink node; (2) be v ^(cur)A hop neighbor; (3) compare v ^(cur)More close target.Can dwindle v greatly like this ⁽ⁱ⁾The zone that floods, the limited zone that floods that we claim that this dwindles is LFZ.

According to this forwarding strategy, node v ^(cur)The data query bag that will flood in its LFZ is about to packet and is transmitted to the contained node of dash area among Fig. 2 (a).

If according to formula (1), node v ^(cur)Can not find suitable next-hop node, promptly LFZ=Φ route " cavity " occurs at this moment, shown in Fig. 2 (b), at this moment, relaxes the condition of formula (1), reselects v according to formula (2) ^(cur)The zone that floods (we are called relaxed LFZ).

relaxed?LFZ(v ^(cur))＝{v ^(j)|v ^(j)∈LFZ(sink)}∩{v ^(k)|v ^(k)∈nbr(v ^(cur))}(2)

Do you how to determine the LFZ of sink node? as shown in Figure 3, suppose that the VELOCITY DISTRIBUTION of certain target is in interval [v _Min, v _Max], t constantly target is positioned at O place, position, and then (zone that the target of T＞t) may exist is to be the center of circle with O to T, and interior ring radius is v constantly _Min* (T-t+ δ), outer shroud radius are v _Max* the circle ring area of (T-t+ δ), wherein δ is the communication delay of sink node to the target area, these data can be got an estimated value by experiment.If t constantly data query bag p begins to flood from the sink node, then sink only needs in Fig. 3 dash area to flood to transmit p get final product, and the node set that the shadow part branch comprises is called the LFZ of sink node, remembers and makes LFZ (sink).

Embodiment 2:

Referring to Fig. 4 present embodiment is described.Present node v ^(cur)What receive is to converge packet (to contain ID _Arp), v ^(cur)Take a kind of greedy forwarding strategy that combines with residue energy of node of transmitting, select to have least estimated cost c (v ^(next), X _s) v ^(next)As next-hop node:

$v^{\left(\mathrm{next}\right)}=\left\{v^{\left(k\right)}\right|v^{\left(k\right)}=\underset{v^{\left(j\right)}}{\arg \min }\left\{c(v^{\left(j\right)},X_s)\right\}\mathrm{andc}(v^{\left(k\right)},X_s)\≤c(v^{\left(\mathrm{cur}\right)},X_s)---\left(3\right)$

and?v ^(k)∈nbr(v ^(cur))}

Nbr (v wherein ^(cur)) be v ^(cur)A hop neighbor node set; C (v ⁽ⁱ⁾, X _S) expression node v ⁽ⁱ⁾Cost function to the sink node.Take all factors into consideration distance and node energy, c (v ⁽ⁱ⁾, X _S) can be expressed as:

c(v ⁽ⁱ⁾，X _s)＝α||v ⁽ⁱ⁾-X _s|| ₂-(1-α)E(v ⁽ⁱ⁾)(4)

Wherein α is adjustable weights, E (v ⁽ⁱ⁾) expression node v ⁽ⁱ⁾Dump energy.From formula (4) as can be seen cost function taken all factors into consideration node and the distance of s ink node and the dump energy of node, when all neighbors dump energies equated or get α=1, it was that the nearest neighbors of chosen distance target is as next-hop node that this algorithm just develops into traditional greedy algorithm; When distance equated or gets α=0, selecting to have maximum residual energy node was next-hop node.So both packet was advanced as early as possible to destination node, energy consumption that again can all nodes of balance.

In Fig. 4 (a), v ^(cur)Select next-hop node according to formula (3), if only consider distance, then next-hop node is node E).

If at v ^(cur)Transmit in the data, the communication cavity occurs, promptly to v ^(k)∈ nbr ^(vur)), c (v is all arranged ^(k), X _s) c (v ^(cur), X _s), v (k) ∈ nbr (v ^(cur)).At this moment v ^(cur)Can't transmit principle according to greediness and find next-hop node v ^(next), shown in Fig. 4 (b).

At this moment, our method is according to transmitting principle as early as possible, relaxing the condition in the formula (3), i.e. v ^(cur)Next redirect send out node v ^(next)Get final product so long as cost is minimum in its neighbor node, and no longer require v ^(next)Cost compares v ^(cur)Littler.That is:

$v^{\left(\mathrm{next}\right)}=\underset{v^{\left(k\right)}\∈\mathrm{nbr}\left(v^{\left(\mathrm{cur}\right)}\right)}{\arg \min \left\{c(v^{\left(k\right)},X_s)\right\}}---\left(5\right)$

From Fig. 4 (b) as can be seen, if only consider distance, then v ^(next)Be node A.A kind of opposite extreme situations is the v that obtains according to formula 5 ^(next)Just be v ^(pri), i.e. v ^(cur)Next-hop node return to its previous dive node, shown in Fig. 4 (c).At this moment packet p will be at v ^(cur)And v ^(pri)Between back and forth circulation transmit, exhaust until node energy, we claim that this phenomenon is the route endless loop.The route endless loop occurring is to cause owing to node density is low excessively, in case the route endless loop occurs, can start a kind of mechanism of rerouting that retreats, by v ^(cur)Send and re-route bag p to its upstream node v ^(pri), inform v ^(pri)The route endless loop appears, by v ^(pri)Reselect next-hop node, and when selecting next-hop node, no longer consider oneself (v ^(cur)), jump by slow astern like this and can solve the endless loop routing issue.This moment v ^(pri)Reselect its next-hop node according to formula 6, be designated as v ^(r-next)):

$v^{(r-\mathrm{next})}=\underset{v^{\left(k\right)}}{\arg \min }\{c(v^{\left(k\right)},X_s),c(v^{\left(\mathrm{pri}\right)},X_s)\},v^{\left(k\right)}\∈\{\mathrm{nbr}\left(v^{\left(\mathrm{pri}\right)}\right)-\left\{v^{\left(\mathrm{cur}\right)}\right\}\}---\left(6\right)$

Claims (2)

1. route selection method for wireless sensor network that object-oriented tracking is used, form by two parts:

(1) the sink node is to the data query package transmitting method QPR of target: adopt the greediness of based target zone of action to transmit and the limited forwarding strategy that floods and combine;

(2) target converges data packet greedy retransmission method APR to the sink node: adopt the forwarding strategy that greediness is transmitted and residue energy of node combines based on the sink node location, wherein

Greedy forwarding and the limited forwarding strategy that combines that floods are: the selection of forward node need meet the following conditions simultaneously:

(1) is among the LFZ of sink node;

(2) be a hop neighbor of present node;

(3), promptly select next-hop node according to following formula than the more close target of present node:

LFZ(v ^(cur))＝{v ^(j)|v ^(j)∈LFZ(sin?k)}∩{v ^(k)|v ^(k)∈nbr(v ^(cur))，

And

Wherein, v ^(cur)And v ^(next)Be respectively current forward node and next redirect and send out node, LFZ (sin k) is the limited node set that floods of sink node, nbr (v ^(cur)) be v ^(cur)A hop neighbor node set, And X _OThe geographical position of representing present node and center, target area respectively, | X _k-X _O| and

Represent a certain node v respectively ^(cur)A certain neighbor node v ^(k)And v ^(cur)Euclidean distance with the center, target area;

The forwarding strategy that greediness is transmitted and residue energy of node combines based on the sink node location is: packet selects to have least estimated cost c (v converging the routing procedure from destination node to the sink node ^(next), X _s) v ^(next)As next-hop node: promptly select next-hop node according to following formula:

Wherein, v ^(cur)And v ^(next)Be respectively current forward node and next redirect and send out node, nbr (v ^(cur)) be a hop neighbor node set of current forward node;

The estimation cost c (v that node is selected ^(next), X _s) computational methods be to take all factors into consideration distance and node energy, a certain node v ⁽ⁱ⁾Estimation cost c (v to the sink node ⁽ⁱ⁾, X _s) be expressed as:

c(v ⁽ⁱ⁾，X _s)＝α||v ⁽ⁱ⁾-X _s|| ₂-(1-α)E(v ⁽ⁱ⁾)

X wherein _sBe the geographical coordinate of sink node, α is adjustable weights, E (v ⁽ⁱ⁾) expression node v ⁽ⁱ⁾Dump energy, cost function has been taken all factors into consideration the distance of node and sink node and the dump energy of node as can be seen from formula, when all neighbors dump energies equated or get α=1, it was that the nearest neighbors of chosen distance target is as next-hop node that this algorithm just develops into traditional greedy algorithm; When distance equated or gets α=0, selecting to have maximum residual energy node was next-hop node.

2. the route selection method for wireless sensor network that object-oriented tracking according to claim 1 is used, it is characterized in that: the concrete steps of described method are:

Step 1: carry out the netinit process, obtain neighbor information by information exchange between node, and in routing table, preserve a hop neighbor information;

Step 2: after node is received packet, at first by destination node ID judge this packet be the data query bag that sends by the sink node or send from the target area converge packet;

Step 3: if the data query bag, then execution in step 4; Otherwise execution in step 5;

Step 4: start the data query package transmitting method of sink node to target;

Step 41: transmit the limited regional LFZ that floods that determines present node with the limited principle that combines of flooding according to greediness;

Step 42: judge whether LFZ is empty set, if be empty set then execution in step 421, otherwise execution in step 423;

Step 421: the cavity exists, and relaxes the limited condition that floods, and redefines the LFZ of node;

Step 422: by the lax LFZ data query bag that floods;

Step 423: by the LFZ data query bag that floods;

Step 5: start target and converge the data packet greedy retransmission method to the sink node;

Step 51:, find out node with minimum cost according to the estimation cost of the principle calculating neighbor node that greediness is transmitted and dump energy combines;

Step 52: whether the minimum cost of judging this node is less than the estimation cost of present node, if be not less than, then execution in step 521, otherwise execution in step 524;

Step 521: have the cavity, relax greedy forwarding condition, reselect next-hop node;

Step 522: if selected node is a last hop node of present node just, illustrate to have the route endless loop, change step 523, otherwise change step 524;

Step 523: start slow astern and jump the mechanism of rerouting, present node notifies its upstream node to reselect next-hop node, and does not consider oneself when selecting, and upstream node changes step 51;

Step 524: this node is as the next-hop node of present node;

Step 525: present node is transmitted and is converged packet.

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