CN103501270A - Rapid node cluster head recommending method - Google Patents

Abstract

The invention relates to a rapid node cluster head recommending method. The method comprises the steps: establishing clusters, of which each contains a certain number of vehicle nodes, according to corresponding road settings, and enabling the dividing of the clusters to have a minimum number, wherein all the clusters contain all vehicle nodes, and each vehicle node only belongs to one cluster; comparing edge weights among the vehicle nodes in each vehicle node cluster, so as to generate minimum spanning trees of corresponding clusters; comparing the mean values of vehicle node receiving signal-to-noise ratios at the two ends of each minimum weight edge, and recommending greater values as cluster heads. According to the method, the principle of the minimum spanning tree is utilized, the cluster head recommending time is reduced through the one-way comparison and descending calculation among the vehicle nodes, and the validity of traffic safety information dissemination is improved through improving the stability of the cluster heads.

Description

A kind of node cluster cluster head is elected method fast

Technical field

The present invention relates to intelligent transport technology, relate in particular to the election method for car node cluster cluster head in the car networking.

Background technology

The car networking is intelligent transportation system (Intelligent Transportation System, ITS) information gathering, carrying and transmission platform, can comprehensively carry traffic safety information, traffic administration efficiency information, traffic commerce services information and internet, applications information.Wherein, traffic safety information effectively, needs in the finite element network scope, to propagate rapidly and accurately in limited region and finite time-domain scope, and the car node can be responded traffic events in time, plays the safe early warning effect.

Traffic safety information message is brief, position relevant, and user's datagram protocol (User Datagram Protocol, UDP) is broadcasted.But traffic safety information is often followed the generation (or early warning) of traffic accident and is produced in a large number, forms high density security information burst flow.Simultaneously, in short distance, in the short time, the car node is a large amount of the gathering because traffic behavior worsens, and makes the car node in the high density distribution.So, in limited region and finite time-domain scope, high density car node is to the repeated broadcast of identical traffic safety information the deficient in short-term of network radio resources in territory that cause the accident, the end-to-end propagation of security information produces great time delay and serious information dropout rate, makes the traffic safety information received be run ragged and maybe can't resolve.The information redundancy caused for reducing the traffic safety information repeated broadcast, a plurality of car nodes in certain limit are created as to node cluster (Cluster), and elect certain car node and serve as cluster head (Cluster Head) temporarily, fusion treatment and the broadcast of security information in being undertaken bunch by cluster head, in bunch, other car nodes only receive the traffic safety information of cluster head broadcast.But, it is certain ageing that speed of a motor vehicle otherness on the frequent lane change in crossing, city and highway makes cluster head car node have, therefore, for example, when cluster head lost efficacy (cluster head car node sails out of this bunch), the car node cluster need to elect fast new cluster head take over bunch in the management of traffic safety information.

At present, it is mainly some from node cluster scope, connectedness, car node mobility and computing capability etc. that car node cluster cluster head is elected algorithm or cluster head is relatively elected in several key element weightings in twos, exist the election amount of calculation large, easily be absorbed in and repeat relatively to wait deficiency, cause cluster head election time delay large, poor in timeliness, can not meet the needs of traffic safety information fast propagation.

Summary of the invention

The object of the invention is to overcome the deficiency of above-mentioned prior art, utilize the minimum spanning tree principle to provide in the networking of a kind of car car node cluster cluster head to change stylish cluster head and elect a kind of node cluster cluster head fast and elect fast method, this invention realizes by following technical proposals.

Described node cluster cluster head is elected method fast, comprises,

According to corresponding road arrange set up comprise some cars node bunch, and the division made bunch has minimum number, all bunches comprise whole car nodes, and each car node only belongs to one bunch;

Relatively the weights on limit between the car node in each car node cluster, generate the minimum spanning tree of corresponding bunch;

The two ends car node received signal to noise ratio average on more minimum weights limit, electing the higher value person is cluster head.

Described node cluster cluster head elect fast method further design be, the described method with division of minimum number bunch is to make the division S of car node set V, { V ₁, V ₂... V _qmeet each V _iall a complete subgraph, and to all i, j=1,2. ..q and i ≠ j all have

the time, q is minimum value gained car node set V _i, be designated as car node cluster C _i, i=1,2 ... q;

Wherein: i is i car node cluster in car node set V, and j is j car node cluster in car node set V.

Described node cluster cluster head is elected fast method and is further designed and be, between described car node, the weights on limit are w (e), generates the minimum spanning tree w (T) of corresponding bunch, and has

$w\left(T\right)=\underset{T}{\min }\underset{e\∈T}{\mathrm{\Σ}}w\left(e\right).$

Described node cluster cluster head is elected fast method and is further designed and be, described weight w (e) is car node mobility average

with node to the spacing average

weighted sum

$w\left(e\right)=a\stackrel{\‾}{M_v}+b\stackrel{\‾}{D_v}$

Wherein: a, b is respectively weight coefficient,

for car node mobility average, for the car node to the spacing average.

Described node cluster cluster head is elected fast method and is further designed and be, described weight coefficient a, and b elects target according to cluster head and sets, and when described target is stability, gets a>b, and a+b=1; When described target is decided to be recommended cluster head in bunch center, get a<b, and a+b=1, default value is got a=b=0.5.

Described node cluster cluster head is elected fast method and is further designed and be, described car node mobility average

with the car node to the spacing average

be calculated as follows and obtain,

$\left\{\begin{array}{c}\stackrel{\&OverBar;}{M_v}=\frac{1}{T}{\mathrm{\&Sigma;}}_{t=1}^t\sqrt{{(X_t-X_{t-1})}^2+{(Y_t-Y_{t-1})}^2}\\ \stackrel{\&OverBar;}{D_v}=\frac{1}{N^{\&prime;}-1}{\mathrm{\&Sigma;}}_{d=1}^{N^{\&prime;}-1}\sqrt{{(X_s-X_d)}^2+{(Y_s-Y_d)}^2}\end{array}\right.$

Wherein, T is computing cycle, (X _s, Y _s) for working as the position coordinate value of front truck node from the navigation system acquisition, (X _d, Y _d) be target carriage node location coordinate figure.

Described node cluster cluster head elect fast method further design be, described car node received signal to noise ratio average be car node communication module received bunch in the mean value of other car node signal to noise ratio

$\stackrel{\&OverBar;}{\mathrm{SNR}}=\frac{1}{N-1}{\mathrm{\&Sigma;}}_1^{N-1}\frac{P_r}{N_r}$

Wherein:, P _rand N _rbe respectively transmit signal power and the noise power of r the car node to thering is N car node cluster, r=1,2 ..., N-1.

Described node cluster cluster head is elected fast method and is further designed and be, the two ends car node received signal to noise ratio average on described more minimum weights limit, and the method that election higher value person is cluster head specifically comprises:

In bunch, all N car nodes all claim that oneself is for candidate's cluster head, and an optional car node forms corresponding subgraph G ₁;

Relatively and bunch in the weight w (e) on limit between other node, get the connected node of minimum edge weights and form new subgraph, this figure is the subgraph G that comprises k-1 car node _k-1;

Comparison diagram G _k-1in each node and (G ₀-G _k-1) in the weights on each internodal all limits, get the minimum value connected node, form new subgraph G _k, k=2 ..., N,

If k<N, repeat above-mentioned comparison step; If k=N, stop above-mentioned comparison step, obtain minimum spanning tree G _n;

Two end nodes to minimum weights limit carry out the received signal to noise ratio average

relatively, select the root node H that the maximum is this generation _k, and as this bunch of cluster head H=H _k;

Bunch in broadcast " member " information, receive other car node for this bunch of member node, bunch member node is replied " head " message and is confirmed, when the car node is received " member " information, the propagation of traffic safety information in no longer participating in bunch, until system again initialization carry out the cluster head renewal.

The foundation that said method comprises the car node cluster and quick process of electing single bunch of cluster head.Bunch process of establishing in, each bunch at least comprises a car node, each car node belongs to and only belongs to some bunch, the number of clusters amount of setting up is minimum.In cluster head election process, considered cluster head stability, bunch connectedness and the reliability of cluster head node, and require the capable of dynamic adjustment to elect condition according to the difference of system applies scene.Subsequently, bunch interior nodes is set up to minimum spanning tree according to the election condition value (weights) calculated, and two car nodes on minimum weights limit on spanning tree are carried out to the received signal to noise ratio average relatively, select the root node that the higher value node is this spanning tree, and elect as cluster head.Therefore, the present invention utilizes the minimum spanning tree principle, reduces cluster head by the unidirectional comparison between the car node and the calculating of falling progressively and elects the time, by the stability that improves cluster head, improves the validity that traffic safety information is propagated.

Sum up thus the present invention, will produce useful like this technique effect: it is minimum that (1) sets up by minimum division methods the number of clusters amount that comprises whole car nodes, guarantees to have reduced system complexity under the system connectivity prerequisite.(2) the cluster head formation speed is fast, in the mode of cluster head management bunch information, has saved the control channel resource, has improved the ageing and reliability of communication under high density traffic safety information state.(3) cluster head is relatively stable, and reliability is strong.Each bunch all generates a minimum spanning tree, and bunch interior nodes can not become ring, therefore can not form circulation weights repeatedly between node relatively, and the cluster head tree root that is minimum spanning tree, have higher relative position concentration degree and information reception reliability preferably.

The accompanying drawing explanation

Fig. 1 is car node cluster model, has described all car nodes car node cluster model according to relative running velocity and two constraintss foundation of relative distance on identical travel direction.

Fig. 2 is that cluster head is elected flow chart, has described car node in single bunch and has elected the realization flow of cluster head based on the minimum spanning tree principle.

Embodiment

Below in conjunction with specific embodiment, the present invention will be further described

The present embodiment is according to the car node cluster model that two tracks are set up in the same way, referring to Fig. 1.Because the car node will communicate, so all car nodes must be equipped with the Position Fixing Navigation System of similar Global Navigation System GPS or Beidou satellite navigation system and the corresponding car required communication module of networking, and can intercom mutually in twos between the car node in the distance threshold value scope.

Network after required hardware condition having possessed above-mentioned car, in the car networking, can implement the inventive method, it mainly comprises the steps:

1) according to corresponding road arrange set up comprise some cars node bunch, and the division made bunch has minimum number, all bunches comprise whole car nodes, and each car node only belongs to one bunch;

2) compare the weights on limit between the car node in each car node cluster, generate the minimum spanning tree of corresponding bunch;

3) the two ends car node received signal to noise ratio average on more minimum weights limit, electing the higher value person is cluster head.

Foundation for the node cluster of car described in step 1) refers to that the car node that a sequence is associated on some attribute is configured to singleton, as attribute characteristics such as distance range, relative velocities.For example set the threshold value v that the car node detects the internodal distance threshold value D of adjacent car, relative road speed, setting urban district for distance threshold value D is 500 meters, and highway is 2000 meters; For the threshold value v of relative road speed, urban district is 10km/h, and highway is 20km/h.When the car node detect with adjacent car node between spacing be less than when distance threshold value D and relative road speed are less than speed threshold value v and add other both at isolated node bunch or set up new node cluster, and carry out the election of cluster head.When bunch in car node when serving as cluster head or being subject to the cluster head node administration, will not be re-used as isolated node and add other bunches, can set up metastable car node cluster model on track in the same way, and periodically carry out bunch member and upgrade.In addition, the connectedness that the staple that forms the car node cluster comprises bunch, bunch size and the quantity that comprises required bunch of all nodes.

Further, described car node cluster adopts minimum partitioning algorithm to set up, and adopts the division methods with minimum number bunch, specific as follows:

In the car node, establish the division S={V that forms car node set V in corresponding car meshed network figure G ₁, V ₂... V _qmeet each V _iall a complete subgraph, and to all i, j=1,2 ... q and i ≠ j all have

the time, q is minimum value gained car node set V _i, be designated as car node cluster C _i, i=1,2 ... q.

Above-mentioned i is i car node cluster in car node set V; J is j car node cluster in car node set V, be and i another car node cluster that node cluster is different, but belong to car node set V, the node set V of q such bunch common complete, that is to say the small set that whole node set V is divided into to a separate q non-overlapping copies, such as being divided into 4 little car node clusters to all car node set V in the 2000m scope by distance 500m, be q=1,2,3,4.

mean empty set, that is to say and not there will be a node to appear at this situation in two different car node clusters simultaneously;

expression is sued for peace from all variablees of 1 to q to i, closes and has comprised whole car nodes.

It is cluster head that the present invention utilizes the minimum spanning tree principle to elect optimal node, therefore for step 2), bunch in all node N pie graph G, every limit of this figure is designated as e, give a certain real number w in this limit (e), be called the weights of limit e, scheme the minimum spanning tree of G for meeting the tree T of formula (1), be minimum spanning tree w (T)

$w\left(T\right)=\underset{T}{\min }\underset{e\&Element;T}{\mathrm{\&Sigma;}}w\left(e\right)---\left(1\right)$

Subsequently in step 3), to two car node received signal to noise ratio averages on the upper minimum weights of this spanning tree T limit

compare, select the root node N of maximum node as spanning tree _rr=1,2 ..., N, electing root node is this car node cluster cluster head.

In described figure, the weight w on limit (e) is car node mobility average

with node to the spacing average

weighted sum has:

$w\left(e\right)=a\stackrel{\&OverBar;}{M_v}+b\stackrel{\&OverBar;}{D_v}---\left(2\right)$

In above-mentioned (2) formula, a, b is weight coefficient, according to cluster head, elects goal-setting.For example can set like this: when the cluster head of electing has better stability if wish, get a>b, and a+b=1; If wish the cluster head of recommending when bunch center, get a<b, and a+b=1; Default value is got a=b=0.5.

for car node mobility average, for the car node, to the spacing average, they can calculate by formula (3),

$\left\{\begin{array}{c}\stackrel{\&OverBar;}{M_v}=\frac{1}{T}{\mathrm{\&Sigma;}}_{t=1}^t\sqrt{{(X_t-X_{t-1})}^2+{(Y_t-Y_{t-1})}^2}\\ \stackrel{\&OverBar;}{D_v}=\frac{1}{N^{\&prime;}-1}{\mathrm{\&Sigma;}}_{d=1}^{N^{\&prime;}-1}\sqrt{{(X_s-X_d)}^2+{(Y_s-Y_d)}^2}\end{array}\right.---\left(3\right)$

Wherein, T is computing cycle, (X _s, Y _s) for working as the position coordinate value of front truck node from the navigation system acquisition, (X _d, Y _d) be target carriage node location coordinate figure, be all the latitude and longitude coordinates value that GPS measures.

In the car node cluster of setting up, the generation of cluster head needs fast, once produce need to stablize, reliably, with real-time and the reliability of traffic safety information transmission in guaranteeing bunch.Cluster head is elected flow process referring to Fig. 2, and the node weights that this figure has provided bunch interior nodes one-way circulation compare.

In single bunch that is N at all car nodes, pie graph is G.At first, in bunch, each car node all claims that oneself is for candidate's cluster head, and optional a certain car node forms subgraph G ₁; Then, relatively and bunch in the weight w (e) on limit between other node, get the connected node of minimum edge weights and form new subgraph.If comprised the subgraph G of k-1 car node _k-1, compare G _k-1in each node and (G ₀-G _k-1) in the weights on each internodal all limits, get the minimum value connected node, form new subgraph G _k, k=2 ..., N.If k<N, repeat above-mentioned comparison step; If k=N, stop above-mentioned comparison step, obtain minimum spanning tree G _n.Subsequently, two end nodes on minimum weights limit carried out to the received signal to noise ratio average

relatively, select the root node H that the maximum is this generation _k, and as this bunch of cluster head H=H _k.Simultaneously, bunch in broadcast " member " information, receive other car node for this bunch of member node, bunch member node is replied " head " message and is confirmed.When the car node is received " member " information, the propagation of traffic safety information in no longer participating in bunch, until system again initialization carry out the cluster head renewal.

This cluster head election method is utilized minimum spanning tree unidirectional condition comparative advantages, elect fast cluster head while upgrading with the car node cluster in newly-generated car node cluster, produce the unidirectional spanning tree of cluster knot point by the condition weights of relatively describing cluster head stability and bunch connectedness, the node received signal to noise ratio average at two ends, more minimum weights limit subsequently, electing the excellent car node of combination property is cluster head.The method amount of calculation is little, and the cluster head formation speed is fast, and the cluster head stability of generation is high, and cluster head Information Communication reliability is strong, is applicable to the fast propagation of traffic safety information in the car networking of fast moving.

Claims (8)

1. a node cluster cluster head is elected method fast, it is characterized in that comprising,

According to corresponding road arrange set up comprise some cars node bunch, and the division made bunch has minimum number, all bunches comprise whole car nodes, and each car node only belongs to one bunch;

Relatively the weights on limit between the car node in each car node cluster, generate the minimum spanning tree of corresponding bunch;

The two ends car node received signal to noise ratio average on more minimum weights limit, electing the higher value person is cluster head.

2. a kind of node cluster cluster head according to claim 1 is elected method fast, it is characterized in that the described method with division of minimum number bunch is to make the division S={V of car node set V ₁, V ₂... V _qmeet each V _iall a complete subgraph, and to all i, j=1,2 ... q and i ≠ j all have

the time, q is minimum value gained car node set V _i, be designated as car node cluster C _i, i=1,2 ... q;

Wherein: i is i car node cluster in car node set V, and j is j car node cluster in car node set V.

3. a kind of node cluster cluster head according to claim 1 and 2 is elected method fast, and the weights that it is characterized in that limit between described car node are w (e), generates the minimum spanning tree w (T) of corresponding bunch, and has

$w\left(T\right)=\underset{T}{\min }\underset{e\&Element;T}{\mathrm{\&Sigma;}}w\left(e\right).$

4. a kind of node cluster cluster head according to claim 3 is elected method fast, it is characterized in that described weight w (e) is car node mobility average

with node to the spacing average weighted sum

$w\left(e\right)=a\stackrel{\&OverBar;}{M_v}+b\stackrel{\&OverBar;}{D_v}$

Wherein: a, b is respectively weight coefficient, for car node mobility average,

for the car node to the spacing average.

5. a kind of node cluster cluster head according to claim 4 is elected method fast, it is characterized in that described weight coefficient a, and b elects target according to cluster head and sets, and when described target is stability, gets a>b, and a+b=1; When described target is decided to be recommended cluster head in bunch center, get a<b, and a+b=1, default value is got a=b=0.5.

6. a kind of node cluster cluster head according to claim 4 is elected method fast, it is characterized in that described car node mobility average

with the car node to the spacing average

be calculated as follows and obtain,

$\left\{\begin{array}{c}\stackrel{\&OverBar;}{M_v}=\frac{1}{T}{\mathrm{\&Sigma;}}_{t=1}^t\sqrt{{(X_t-X_{t-1})}^2+{(Y_t-Y_{t-1})}^2}\\ \stackrel{\&OverBar;}{D_v}=\frac{1}{N^{\&prime;}-1}{\mathrm{\&Sigma;}}_{d=1}^{N^{\&prime;}-1}\sqrt{{(X_s-X_d)}^2+{(Y_s-Y_d)}^2}\end{array}\right.$

Wherein, T is computing cycle, (X _s, Y _s) for working as the position coordinate value of front truck node from the navigation system acquisition, (X _d, Y _d) be target carriage node location coordinate figure.

7. a kind of node cluster cluster head according to claim 4 is elected method fast, it is characterized in that described car node received signal to noise ratio average be car node communication module received bunch in the mean value of other car node signal to noise ratio

$\stackrel{\&OverBar;}{\mathrm{SNR}}=\frac{1}{N-1}{\mathrm{\&Sigma;}}_1^{N-1}\frac{P_r}{N_r}$

Wherein:, P _rand N _rbe respectively transmit signal power and the noise power of r the car node to thering is N car node cluster, r=1,2 ..., N-1.

8. a kind of node cluster cluster head according to claim 7 is elected method fast, it is characterized in that the two ends car node received signal to noise ratio average on described more minimum weights limit, and the method that election higher value person is cluster head specifically comprises:

In bunch, all N car nodes all claim that oneself is for candidate's cluster head, and an optional car node forms corresponding subgraph G ₁;

Relatively and bunch in the weight w (e) on limit between other node, get the connected node of minimum edge weights and form new subgraph, this figure is the subgraph G that comprises k-1 car node _k-1;

Comparison diagram G _k-1in each node and (G ₀-G _k-1) in the weights on each internodal all limits, get the minimum value connected node, form new subgraph G _k, k=2 ..., N,

If k<N, repeat above-mentioned comparison step; If k=N, stop above-mentioned comparison step, obtain minimum spanning tree G _n;

Two end nodes to minimum weights limit carry out the received signal to noise ratio average

relatively, select the root node H that the maximum is this generation _k, and as this bunch of cluster head H=H _k;

Bunch in broadcast " member " information, receive other car node for this bunch of member node, bunch member node is replied " head " message and is confirmed, when the car node is received " member " information, the propagation of traffic safety information in no longer participating in bunch, until system again initialization carry out the cluster head renewal.

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