CN106131161A - Under a kind of urban environment, vehicle-mounted road based on stability sub-clustering is by protocol method - Google Patents

Abstract

The present invention proposes under a kind of urban environment vehicle-mounted road based on stability sub-clustering by protocol method, including: approximation node clustering collection is formed, election of cluster head and sub-clustering are safeguarded.The formation of approximation node clustering collection refers between the adjacent node that moving direction is identical by Beacon MESSAGE EXCHANGE oneself state information, the translational speed of change at random is modeled as normal distribution model, get rid of and form approximation set of node after the especially big node of bulk velocity difference, create and update approximation node table；Election of cluster head is again the approximation speed of node table interior joint, position and adjacent segments to be counted and be modeled as normal distribution model, selects optimum leader cluster node by calculating competition priority；Sub-clustering maintenance phase processes node pointedly and adds or depart from sub-clustering and sub-clustering merging etc. and ensure the stability of sub-clustering.The sub-clustering mechanism of this method has less bunch head rate of change and a longer bunch head to hold time；Can effectively improve packet-based transport in urban environment and reduce time delay.

Description

Under a kind of urban environment, vehicle-mounted road based on stability sub-clustering is by protocol method

Technical field

The present invention relates to vehicular ad hoc Routing Protocol vehicular ad hoc network technical field, particularly to a kind of city ring Under border, vehicle-mounted road based on stability sub-clustering is by protocol method.

Background technology

Vehicular ad hoc net VANET is that road vehicle and numerous Intelligent mobile equipment couple together built Multi-hop, ad-hoc communication network, be a kind of novel wireless mobile self-organizing network MANET being applied under intelligent transportation environment. Wherein, Routing Protocol is to determine the key technology that VANET COMMUNICATION NETWORK PERFORMANCES is good and bad.Traditional MANET Design of Routing Protocol Consideration is different with VANET, and VANET has, and node motion is quick, network topology change is frequent, communication link is unstable The feature such as complicated with urban traffic environment, this adds the challenge of Design of Routing Protocol undoubtedly.Therefore, design one is stable strong Strong VANET Routing Protocol is to have very important significance.

VANET network in urban environment is be made up of intensive vehicle and numerous smart machines ultra-large Communication network, in order to be able to reduce routing cost and avoid network congestion, uses Routing Protocol based on sub-clustering can improve network and expands Malleability.The node status of planar structure Routing Protocol is the most identical with function, and applies the network of clustering route protocol to be divided For multiple sub-clustering subsets, rank and the function of node are otherwise varied, and each sub-clustering comprises ordinary node, leader cluster node and gateway joint Point three classes.Clustering route protocol generally comprises 4 major parts: cluster algorithm, bunch in route, cluster-level routing and sub-clustering are safeguarded, In bunch member node can directly with bunch head communication, bunch intermediate node can carry out multi-hop communication by bunch head or gateway node, and Leader cluster node needs management and communicates between safeguarding member node and carrying out bunch, and resource overhead is bigger.Therefore, for how to form one Individual stable healthy and strong cluster structured and one rational bunch of head of selection, to reducing router-level topology expense, communication load and lifting net Network overall performance is significant.Typically include CGSR, CBRP etc. based on clustering route protocol.

CGSR Routing Protocol is the clustering route protocol being extended on the basis of DSDV agreement, and leader cluster node needs the cycle Property broadcast, to safeguard whole network topology, causes bigger route maintenance expense.CBRP Routing Protocol is to assist DSR route It is a kind of based on cluster structured source routing on-demand routing protocol that view extension improves, and its LID cluster algorithm is not particularly suited for VANET Network.

Summary of the invention

The present invention is to overcome at least one defect (not enough) described in above-mentioned prior art, it is proposed that under a kind of urban environment Vehicle-mounted road based on stability sub-clustering is by protocol method, and this protocol method sub-clustering based on stability mechanism is than LID and HC sub-clustering Algorithm has less bunch head rate of change and a longer bunch head is held time；AODV and CBRP agreement relatively, this agreement is in city Can effectively improve packet-based transport under environment and reduce time delay.

For reaching above-mentioned purpose, technical scheme particularly as follows:

Under a kind of urban environment, vehicle-mounted road based on stability sub-clustering is by protocol method, comprises the following steps:

First: between the adjacent node in default communication range, carry out switching node by periodically broadcasting Beacon message The status information of self, utilizes statistical analysis technique that the translational speed of vehicle node is modeled as normal distribution model, only chooses Speed node in setting fiducial interval range, gets rid of the node with diversity to reformulate new approximation node clustering Set.After confidence interval is set, speed will be met at V_min≤V_j≤V_maxIn the range of neighbor node will reformulate new Set, and specially create one approximation node table SNT store the node status information in this set.

Second: use adjacent segments to count in election of cluster head mechanism, speed and location parameter calculate competition priority and come Select the leader cluster node of optimum, and the node broadcasts bunch head message in approximation set of node is stable cluster structured to be formed.Weight The new average speed calculating k node in SNT table and average location gap, the set of node in SNT table is unusual in eliminating speed There is usually no the node that velocity deviation is excessive after node, mean deviation statistical therefore can be used to represent sub-clustering collection internal segment The difference degree of point.Ask node i and each node at speed and the mean deviation of location gap again, and seek the speed of node i self With the relative different of location gap Yu integral node meansigma methods, finally calculate the competition priority of node.Once compete priority Maximum, this node just possesses as bunch head both candidate nodes node broadcasts bunch head message packet in SNT table, and adjacent node receives Response message to add sub-clustering stable cluster structured to be formed after information.

3rd: sub-clustering maintenance phase process pointedly node add or depart from sub-clustering and sub-clustering merging etc. cause sub-clustering The situation of structure change.

Leader cluster node departs from sub-clustering: triggers member node when bunch head departs from sub-clustering and re-elects leader cluster node as early as possible, bunch Member node will initiate election of cluster head process in the SNT table safeguarded again, calculates competition priority CP of current time with weight The node of the newly selected replacement.

Bunch member node departs from sub-clustering: single bunch of member node depart from after by losing and contacting between adjacent node, from it Neighbor table and SNT table are deleted the information of this node to update topological database.The node of this disengaging sub-clustering then remove SNT table and Change state is C_UNDECIDED, then regenerates Beacon message notifying adjacent node and adds with sub-clustering again or request Another sub-clustering；If around not having adjacent node, then self becomes leader cluster node.

Node request adds sub-clustering: after a node m being in undefined behavior enters the communication range of a sub-clustering, Will be to the leader cluster node transmission Beacon message of sub-clustering to inform the current information of self, after a bunch head receives information, not Send bunch head broadcasting packet immediately, but first the judgement bunch diversity factor DD between head c and node m decides whether to accept this joint Point.If node m is simultaneously received bunch head broadcasting packet of multiple sub-clustering in communication range, then node m will be wide from multiple bunches of heads Report speed and the positional information obtaining bunch head in literary composition, then select to add which point by the diversity factor calculating node and bunch head Bunch, node m selects to add the sub-clustering that diversity factor is little.

Adjacent sub-clustering merges: in the section, crossing in city, often due to the reason such as vehicle deceleration or stopping makes two points Bunch meeting, generally for reducing the sub-clustering redundancy of overall VANET network, the sub-clustering that member node number is few is incorporated into big sub-clustering In structure.

Again sub-clustering: after setting up cluster structured a period of time, it may be necessary to reselect leader cluster node and divide to maintain The stability of clustering architecture.And, should judge that before re-electing bunch head this leader cluster node is the need of changing its state, bunch cephalomere Point need to obtain from SNT table nodal information and recalculate adjacent segments now count, speed and the meansigma methods of location gap And mean difference, then recalculate its bunch of head competition priority.When the competition priority of leader cluster node meets condition, bunch Head node abandons C_HEAD state and to revise oneself state be C_MEMBER, then by the change of HELLO message statement oneself Situation.Other bunch of member node needs to reselect suitable bunch of head when losing leader cluster node, therefore can directly invoke bunch Head election process.

Under a kind of urban environment, vehicle-mounted road based on stability sub-clustering is by protocol method.The present invention is by the base in CBRP agreement Improving on plinth, introduce a kind of routing mechanism SBCRP based on stability sub-clustering, simulation result shows, SBCRP agreement based on The sub-clustering mechanism of stability has less bunch head rate of change than LID and HC cluster algorithm and a longer bunch head is held time；Phase To AODV and CBRP agreement, SBCRP agreement can effectively be improved packet-based transport in urban environment and reduce time delay.

Relative to prior art, the invention have the advantages that and beneficial effect:

The network topology that the problems such as, skewness, traffic route complexity big for vehicle density in urban environment cause Structure frequently changes the situations such as unstable with communication link, and the present invention proposes a kind of vehicular ad hoc based on stability sub-clustering Network routing protocol (SBCRP agreement).This agreement improves mainly for cluster algorithm, it is ensured that the stability of sub-clustering interior nodes, Then a suitable and stable leader cluster node, finally, stablizing of further maintenance cluster structure are elected.

By the simulation result of the stability sub-clustering of LID, HC cluster algorithm and SBCRP mechanism is analyzed, SBCRP agreement is held time have better performance at bunch head rate of change and a bunch head；The most again by AODV, CBRP and The simulation result of SBCRP agreement carries out comparison and resolves, although indicating SBCRP agreement to add routing cost and computing cost, But improve packet-based transport and reduce end-to-end time delay.

This sub-clustering mechanism is designed mainly for the feature under urban environment, and it can improve cluster structured steady Fixed, reduce network topology structure and frequently change the impact that communication link is brought.It addition, this sub-clustering mechanism is the most also It is equally applicable to the vehicle under High-speed Circumstance, high velocity environment and equally utilizes the letters such as the direction of vehicle, speed and positional distance Breath forms the sub-clustering with certain stability.

Accompanying drawing explanation

Fig. 1 is the forming process figure of approximation node clustering collection.

Fig. 2 is election of cluster head schematic diagram of mechanism.

Fig. 3 is that node request adds clustering process figure.

Detailed description of the invention

Accompanying drawing being merely cited for property explanation, it is impossible to be interpreted as the restriction to this patent；In order to the present embodiment is more preferably described, attached Scheme some parts to have omission, zoom in or out, do not represent the size of actual product；

To those skilled in the art, in accompanying drawing, some known features and explanation thereof may be omitted is to be appreciated that 's.With embodiment, technical scheme is described further below in conjunction with the accompanying drawings.

Under a kind of urban environment, vehicle-mounted road based on stability sub-clustering is by protocol method, comprises the following steps:

First: the formation of approximation node clustering collection, between node can by the direction of Beacon Receive message adjacent node, The information such as speed and position, utilizes statistical analysis technique that the translational speed of vehicle node is modeled as normal distribution model, only choosing The speed of picking up the car node in certain fiducial interval range, gets rid of the node with different to reformulate new approximation joint Point sub-clustering set.After confidence interval is set, speed will be met at V_min≤V_j≤V_maxIn the range of neighbor node will again Form new set, and create an approximation node table SNT specially and store the node status information in this set, and optimum Leader cluster node will use the competition of election of cluster head mechanism to generate in the table.Implement process such as Fig. 1, particularly as follows:

First determine whether that node motion direction is the most identical, if moving direction differs, then abandon Beacon message refusal Node j, terminates；If mobile moving direction is identical, the neighbor table of the most more new node, then calculates the velocity interval of approximation node table V_max, V_min；Decision node j speed V_jWith V_max、V_minRelation, i.e. V_min≤V_j≤V_maxWhether setting up, if be false, then losing Abandon Beacon message refusal node j, terminate；If set up, then node j is added in approximation node table, and update approximation node Table, then terminate.

Second: election of cluster head, in election of cluster head mechanism, use that adjacent segments is counted, speed and location parameter calculate competition Priority selects the leader cluster node of optimum, and the node broadcasts bunch head message in approximation set of node is to form stable sub-clustering Structure.Node i sets up the SNT table node with storage feature similarity after getting rid of abnormal nodes, it is assumed that deposit in this table At k node, in order to compete leader cluster node, parameter model normal state of again speed of node, location gap and adjacent segments being counted Distributed model.When speed and location gap are counted the biggest closer to overall average, adjacent segments, competition priority CP of calculating is more Greatly, to be chosen as the chance of bunch head the biggest for node.

First defined parameters: V_jRepresent the speed of approximation node table interior joint j；Represent the average of approximation node table interior joint Speed；x_j、y_jRepresent the location parameter of approximation node table interior joint j respectively；P_j、Represent that node approximates node table with it respectively The location gap of interior joint j and average location gap；d_cv、d_cpRepresent node c speed and the mean deviation of location gap respectively；d '_cv、d'_cpRepresent the relative different of node c speed and location gap with its meansigma methods respectively；CP represents that bunch head competition of node is excellent First level.

First recalculate the average speed of k node in SNT table and average location gap, be respectively as follows:

$\stackrel{\‾}{v_c}=\frac{1}{k}\underset{j=1}{\overset{k}{\Σ}}{V}_j---\left(1\right)$

$\left\{\begin{array}{c}{P}_j=\sqrt{{(x_i-x_j)}^2+{(y_i-y_j)}^2}\\ \stackrel{\‾}{p_c}=\frac{1}{k}\underset{j=1}{\overset{k}{\Σ}}{P}_j=\frac{1}{k}\underset{j=1}{\overset{k}{\Σ}}\sqrt{{(x_i-x_j)}^2+{(y_i-y_j)}^2}\end{array}\right.---\left(2\right)$

Set of node in SNT table there is usually no, after getting rid of the node that speed is unusual, the node that velocity deviation is excessive, because of This can represent the difference degree of sub-clustering collection interior nodes with mean deviation statistical.So, by formula (1) and the knot of formula (2) gained Fruit can try to achieve node i with each node at speed and the mean deviation of location gap, is respectively as follows:

$d_{cv}=\frac{1}{k-1}\underset{j=1}{\overset{k}{\Σ}}(V_j-\stackrel{\‾}{v_c})---\left(3\right)$

$d_{cp}=\frac{1}{k-1}\underset{j=1}{\overset{k}{\Σ}}(P_j-\stackrel{\‾}{p_c})---\left(4\right)$

Again by the speed of formula (1) to formula (4) gained and position and mean deviation thereof, substitute into formula (5) and formula (6) respectively, try to achieve The speed of node i self and location gap and the relative different of integral node meansigma methods, be respectively as follows:

${d^{\′}}_{cv}=\frac{(V_i-\stackrel{\‾}{v_c})}{d_{cv}}---\left(5\right)$

${d^{\′}}_{cp}=\frac{(P_i-\stackrel{\‾}{p_c})}{d_{cp}}---\left(6\right)$

Finally, the competition priority calculating node is:

$CP={\mathrm{ke}}^{-\left(\right|{d^{\′}}_{cv}|+|{d^{\′}}_{cp}\left|\right)}---\left(7\right)$

The competition priority that once node self calculates is maximum, and this node just can be as bunch head both candidate nodes in SNT table Node broadcasts bunch head message packet, adjacent node receive information after response message add sub-clustering to form stable sub-clustering knot Structure.If node is in undefined behavior or leader cluster node departs from sub-clustering and node carries out approximation spy according to the information of adjacent node Levy node and screen and create SNT table, if nodal test to SNT table non-NULL, then proceed by election of cluster head competition optimum bunch Head node.As in figure 2 it is shown, be election of cluster head mechanism.

(1) first nodal test to SNT table exist and non-NULL after calculate node self competition priority and entrance keep out of the way time Between T_waitTiming course, back off time T_waitDuration by MAC layer competition window determine.

(2) in back off time section, if node receives bunch head broadcasting packet from arbitrary node j, then inquiry sends report Whether the node ID of literary composition is present in SNT table.If not existing, possible reason is the communication range that node j enters node i, but Also not carrying out diversity judgement between two nodes or be judged as both speed there is some difference, node j still sends bunch Head broadcasting packet.Therefore, node i abandons bunch head broadcasting packet of node j, and continues T_waitTiming.

(3) if node j exists in SNT table, then from this message, its CP is obtained_j, and judge whether to meet condition C P_i＜ CP_jIf being unsatisfactory for, still abandon this bunch of head broadcasting packet.

(4) if meeting CP_i＜ CP_j, then competition priority CP of node j_jBigger, and become bunch head of neighbor node, because of This node i is deleted bunch head broadcasting packet of self and removes T_wait, it is then C_ by the status modifier of neighbor table interior joint j HEAD, oneself becomes bunch member node of node j and updates neighbor table information；

(5) as back off time T_waitTiming terminates, and now becomes bunch head of node i still without node, then node i is sentenced again Whether the nodes of disconnected SNT table changes, if nodes increases, then node i recalculates competition priority and starts new Bunch head competition process；

(6) if SNT table nodes does not increases, then node i adjacent node in SNT table sends bunch head broadcasting packet with a surname Cloth oneself becomes this cluster structured interior bunch head, final updating neighbor table information.

3rd: sub-clustering is safeguarded, process node pointedly at sub-clustering maintenance phase and add or depart from sub-clustering and sub-clustering merging Etc. causing the situation of cluster structured change, the at utmost stability of maintenance cluster structure.This sub-clustering mechanism utilizes the office of node Portion's information carries out sub-clustering, i.e. considers that the direction of vehicle, speed, position and adjacent segments the advantageous information such as count to form stable point Clustering architecture, thus be effectively improved packet-based transport and reduce a bunch head change.Need to be to following five class situations at sub-clustering maintenance phase Carry out corresponding process, cluster structured with self-adaptative adjustment.

(1), when departing from sub-clustering for bunch member node, node is in (HELLO_LOSS+1) * HELLO_INTERVAL week When cannot receive HELLO message in the phase, only need to trigger node and from neighbor table and SNT table, remove this node and notify that other saves Point；And the node change state after removing SNT table departing from sub-clustering is C_UNDECIDED, then regenerate Beacon message Notice adjacent node adds a certain sub-clustering with request or re-establishes sub-clustering；If around there is no adjacent node, then self become bunch Head node.

(2), when departing from sub-clustering for leader cluster node, each bunch of member node then triggers self and enters election of cluster head shape Condition, elects the leader cluster node made new advances immediately, and broadcasts bunch head message to SNT table, and its election of cluster head process is consistent with Fig. 2, only needs Directly invoke election of cluster head process.

(3) node m request is added to the scene of sub-clustering, one can be started when node m is in C_UNDECIDED state Intervalometer u_timer, and periodically broadcast HELLO message, then will depart from this shape in time cycle UNDECIDED_PD State；If not receiving any bunch of head broadcasting packet after intervalometer terminates yet, then just change oneself state is C_HEAD.As Entering in really during the timing of u_timer in the communication range of sub-clustering c, node both sides can be circulated a notice of by HELLO message, and Node m can trigger immediately broadcast Beacon message to inform the status information of self, then request add this sub-clustering.Leader cluster node After c receives the Beacon message of a C_UNDECIDED state node, will start to calculate two internodal diversity factoies DD also Judging whether DD is less than threshold value, if meeting condition, then recipient node m transmission bunch head broadcasting packet, the most directly refuse joint Point m, abandons its Beacon message.If node m is not received by a bunch head broadcasting packet, then continue the timing of u_timer intervalometer； If receiving single bunch of head broadcasting packet, then response bunch head response message, and revise the node state of oneself, neighbor table and SNT Table；If node m is simultaneously received a plurality of bunches of head broadcasting packets, then from message, obtains the information of each leader cluster node and count Diversity factor DD between operator node, then selects the leader cluster node of the DD of minimum and sends bunch head response message to add this sub-clustering. Bunch head is same after receiving bunch head response message of node m updates nodes neighbors table and SNT table, and it realizes flow process as shown in Figure 3.

(4) adjacent sub-clustering merges: in the section, crossing in city, often due to the reason such as vehicle deceleration or stopping makes two Sub-clustering is met, and generally for reducing overall VANET network cluster dividing redundancy, the sub-clustering that member node number is few is incorporated into big sub-clustering knot In structure.First, when two sub-clusterings enter communication range each other, and both sides are established a connection by HELLO message, and inform that This bunch of member node number, then judges whether both bunch member node number summations meet n1+n2≤n, if beyond sub-clustering member The restriction of node total number then nonjoinder, otherwise carries out sub-clustering merging.Secondly, leader cluster node triggers broadcast Beacon message, node Diversity factor DD between bunch head is calculated after acquisition information, if DD abandons cluster head status less than threshold value, the leader cluster node of the least sub-clustering, Add another cluster structured.If finally, for its bunch of member node in bunch head communication range, adding sub-clustering the most equally, if not Rebuilding cluster structured the most voluntarily or re-electing leader cluster node, it realizes process with the most consistent.

(5) sub-clustering again: after setting up cluster structured a period of time, may reselect leader cluster node and divide to maintain The stability of clustering architecture.And, should judge that before re-electing bunch head this leader cluster node is the need of changing its state, bunch cephalomere Point need to obtain from SNT table nodal information and recalculate adjacent segments now count, speed and the meansigma methods of location gap And mean difference, then recalculate its bunch of head competition priority.

A) after node competition becomes bunch head, first pass through and judge that the average translational speed of leader cluster node is to arrange between sub-clustering Every.Speed is longer, for c1 less than usual time interval during 10m/s；Speed is then contrary, for c3 more than during 20m/s；Speed is at 10- Intermediate value is then taken, for c2 during 20m/s.

B) an intervalometer c_interval, at the end of intervalometer timing, bunch cephalomere are started after setting up sub-clustering interval Point recalculates competition priority CP_cAnd Rule of judgmentIf meeting condition, node continues to serve as bunch Head, and make sub-clustering intervalometer c_interval reclocking.

If c) CP_cBe worth too small, then the most whether a bunch head still needs to detect has task not complete, i.e. bunch head transmitting data or Carrying out route finding process, therefore, intervalometer still reclocking also waits next sub-clustering chance.

If d) a bunch head is now in idle condition, then changing its state is C_MEMBER, and its state is the most not Change to avoid occurring loop again, and trigger broadcast HELLO message to notify bunch member node.Member node is losing bunch Election of cluster head process is directly invoked again to pick out the leader cluster node of optimum after Tou.

Obviously, the above embodiment of the present invention is only for clearly demonstrating example of the present invention, and is not right The restriction of embodiments of the present invention.For those of ordinary skill in the field, the most also may be used To make other changes in different forms.Here without also cannot all of embodiment be given exhaustive.All at this Any amendment, equivalent and the improvement etc. made within the spirit of invention and principle, should be included in the claims in the present invention Protection domain within.

Claims (5)

1. under a urban environment vehicle-mounted road based on stability sub-clustering by protocol method, it is characterised in that including:

Step 1, forms new approximation node clustering collection: logical between the adjacent node that moving direction in default communication range is identical Cross periodically broadcast Beacon message and come the status information of switching node self, the direction in recycling Beacon message, speed Between degree and velocity standard difference information eliminating adjacent node, feature difference is at the especially big node of preset range, thus each node is formed New approximation node clustering collection；

Step 2, election of cluster head: it is excellent to use in election of cluster head mechanism that adjacent segments is counted, speed and location parameter calculate competition First level selects the leader cluster node of optimum, and this leader cluster node node broadcasts bunch head message in approximation node clustering collection is to be formed Stable is cluster structured；

Step 3, sub-clustering is safeguarded: processes node at sub-clustering maintenance phase and adds or depart from sub-clustering and sub-clustering merging caused sub-clustering knot The situation of structure change.

Method the most according to claim 1, it is characterised in that the process of described step 1 particularly as follows:

Utilize statistical analysis technique that the translational speed of vehicle node is modeled as normal distribution model, choose speed and confidence is being set Node in interval range, gets rid of at the variant node of preset range to reformulate new approximation node clustering set； After specifically confidence interval is set, speed will be met at V_min≤V_j≤V_maxIn the range of neighbor node j reformulate new near Like node clustering set, and establishment one approximation node table SNT stores the node status information in this set specially.

Method the most according to claim 1, it is characterised in that the process that bunch head of described step 2 is chosen is: calculate approximation The average speed of k node and average location gap in node table SNT, then ask node i and each node between speed and position Away from mean deviation, and seek the relative different of the speed of node i self and location gap and integral node meansigma methods, finally calculate joint The competition priority of point；Once competition priority is maximum, and this node just possesses as bunch head both candidate nodes to approximation node table SNT In node broadcasts bunch head message packet, adjacent node receive information after response message add sub-clustering to form stable sub-clustering Structure.

Method the most according to claim 3, it is characterised in that calculate the average speed of k node in approximation node table SNTAnd the mean place spacing between approximation node table SNT interior joint i and other nodesIt is respectively as follows:

$\stackrel{\‾}{v_c}=\frac{1}{k}\underset{j=1}{\overset{k}{\Σ}}{V}_j---\left(1\right)$

$\left\{\begin{array}{c}{P}_j=\sqrt{{(x_i-x_j)}^2+{(y_i-y_j)}^2}\\ \stackrel{\‾}{p_c}=\frac{1}{k}\underset{j=1}{\overset{k}{\Σ}}{P}_j=\frac{1}{k}\underset{j=1}{\overset{k}{\Σ}}\sqrt{{(x_i-x_j)}^2+{(y_i-y_j)}^2}\end{array}\right.---\left(2\right)$

In above formula, V_jRepresent the speed of approximation node table interior joint j, P_jRepresent the position between approximation node table SNT interior joint i and j Put spacing, x_i、y_iRepresent the location parameter of approximation node table SNT interior joint i, x respectively_j、y_jRepresent approximation node table SNT respectively The location parameter of interior joint j,

Node i and other nodes mean deviation d in speed is tried to achieve by the result of formula (1) and formula (2) gained_cvWith node i and other Node is at the mean deviation d of location gap_cp, it is respectively as follows:

$d_{cv}=\frac{1}{k-1}\underset{j=1}{\overset{k}{\Σ}}(V_j-\stackrel{\‾}{v_c})---\left(3\right)$

$d_{cp}=\frac{1}{k-1}\underset{j=1}{\overset{k}{\Σ}}(P_j-\stackrel{\‾}{p_c})---\left(4\right)$

Formula (1) to formula (4) is substituted into formula (5) and formula (6) respectively, tries to achieve speed and the integral node meansigma methods of node i self Relative different d'_cvRelative different d' with location gap Yu integral node meansigma methods_cp, it is respectively as follows:

${d^{\′}}_{cv}=\frac{(V_i-\stackrel{\‾}{v_c})}{d_{cv}}---\left(5\right)$

${d^{\′}}_{cp}=\frac{(P_i-\stackrel{\‾}{p_c})}{d_{cp}}---\left(6\right)$

Finally, competition priority CP calculating node is:

$\mathrm{CP}={\mathrm{ke}}^{-\left(\right|{d^{\′}}_{\mathrm{cv}}|+|{d^{\′}}_{\mathrm{cp}}\left|\right)}---\left(7\right).$

Method the most according to claim 1, it is characterised in that the sub-clustering of described step 3 is safeguarded and included:

Leader cluster node departs from sub-clustering: triggers member node when bunch head departs from sub-clustering and re-elects leader cluster node as early as possible, bunch member Node, by again initiating election of cluster head process in the approximation node table SNT safeguarded, calculates competition priority CP of current time To reselect the node of replacement；

Bunch member node departs from sub-clustering: single bunch of member node depart from after by losing and contacting between adjacent node, from its neighbours Table and approximation node table SNT delete the information of this node to update topological database；The node of this disengaging sub-clustering is then removed closely It is C_UNDECIDED like node table SNT and change state, then regenerates Beacon message notifying adjacent node again to divide Bunch or request add another sub-clustering；If around not having adjacent node, then self becomes leader cluster node；

Node request adds sub-clustering: after a node m being in undefined behavior enters the communication range of a sub-clustering, it will To the leader cluster node transmission Beacon message of sub-clustering to inform the current information of self, after a bunch head receives information, the most immediately Send bunch head broadcasting packet, but first the judgement bunch diversity factor DD between head c and node m decides whether to accept this node；If Node m is simultaneously received bunch head broadcasting packet of multiple sub-clustering in communication range, then node m will be from multiple bunches of head broadcasting packets The speed of middle acquisition bunch head and positional information, then select to add which sub-clustering by the diversity factor calculating node and bunch head, joint Point m selects to add the sub-clustering that diversity factor is little；

Adjacent sub-clustering merges: in order to reduce the sub-clustering redundancy of overall VANET network, sub-clustering few for member node number be merged into greatly Cluster structured in；

Again sub-clustering: after setting up cluster structured time period T, it may be judged whether leader cluster node to be reselected is to maintain sub-clustering knot The stability of structure；Should judge before re-electing bunch head that this leader cluster node needs the need of its state of change, leader cluster node simultaneously To obtain from approximation node table SNT nodal information and recalculate adjacent segments now count, speed and location gap flat Average and mean difference thereof, then recalculate its bunch of head competition priority；When the competition priority of leader cluster node meets condition Time, leader cluster node abandons C_HEAD state and to revise oneself state be C_MEMBER, then by HELLO message statement oneself Situation of change；Other bunch of member node needs when losing leader cluster node to reselect a bunch head, it is possible to directly invoke election of cluster head Process.