CN103338441B - Based on data transmission method and the system of track of vehicle - Google Patents

Abstract

The present invention relates to a kind of data transmission method based on track of vehicle and system.Wherein, the data transmission method based on track of vehicle comprises: on all vehicles, arrange mobile node, arranges stationary nodes, arrange source node at Network Access Point at partial intersection crossing; When source node needs to send message to object vehicle, whether the travel track judging object vehicle there is stationary nodes; If have, source node searches message transfer tail node on the travel track of object vehicle; Each Node distribution position in vehicle travel track prediction each moment that source node reports according to each mobile node, then according to minimum message propagation delay time principle, the message transmission time delay according to Node distribution position and node selects source node to the transmission node sequence of tail node; By message along transmission node sequence transmission to tail node, tail node is transmitted to the mobile node on object vehicle again.Invention increases the validity and reliability of transfer of data, also effectively reduce transfer of data cost simultaneously.

Description

Based on data transmission method and the system of track of vehicle

Technical field

The present invention relates to the communications field, particularly relate to a kind of data transmission method based on track of vehicle and system.

Background technology

Current VANET(VehicularAd-hocNetwork, vehicle self-organizing network) in infrastructure-to-vehicle(Internet access points to moving vehicle) data transmission method mainly contains the infrastructure-to-vehicle data transfer algorithms based on trajectory predictions that the people such as Tian proposes, and proposes the infrastructure-to-vehicle data transfer mode based on object vehicle travel track first.This algorithm supposes that there is a stationary nodes each intersection, when having message to need to send, prediction destination node (mobile node namely on object vehicle) is by a series of stationary nodes of process, and therefrom find a stationary nodes, when making the message of source node arrive this stationary nodes, destination node is about to the maximization arriving or just arrive.This algorithm solves the problems such as the large and success rate of infrastructure-to-vehicle propagation delay time shake is low, but owing to installing stationary nodes in each intersection of needs, larger to VANET networking demand, maintenance cost is very high, its achievement in research is difficult to directly apply in reality, can not become the final effective means of dealing with problems.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of data transmission method based on track of vehicle and system, reduces the cost of transfer of data.

For solving the problems of the technologies described above, the present invention proposes a kind of data transmission method based on track of vehicle, comprising:

Step one, all vehicles arrange mobile node, at partial intersection crossing, stationary nodes is set, at Network Access Point, source node is set, each mobile node, each stationary nodes and described source node all can calculate the message transmission time delay that self arrives arbitrary stationary nodes, and the travel track of place vehicle can be reported described source node by each mobile node in advance;

Step 2, when described source node needs to send message to object vehicle, whether the travel track judging described object vehicle has stationary nodes, if having, performs step 3;

Step 3, described source node searches last stationary nodes of message transfer on the travel track of described object vehicle, be called tail node, described tail node meets: described source node is less than or equal to the advance time delay of described object vehicle to described tail node to the message transmission time delay of described tail node;

Step 4, the Node distribution position in vehicle travel track prediction each moment that described source node reports according to each mobile node, described source node comprises stationary nodes and mobile node to the transmission node in the transmission node sequence of described tail node, described source node is according to minimum message propagation delay time principle, and the message transmission time delay according to described Node distribution position and node selects described transmission node;

Step 5, by message along described transmission node sequence transmission to described tail node, message is transmitted to the mobile node on described object vehicle by described tail node.

Further, the above-mentioned data transmission method based on track of vehicle also can have following characteristics, in described step 4, the described message transmission time delay according to described each Node distribution position and each node is selected to be comprised by the transmission node sequence of described source node to described tail node:

Step a, selects the stationary nodes in described transmission node sequence, is called constant transmissions node, makes by described source node minimum to total message transmission time delay of the transmission path of described tail node through each constant transmissions node;

Step b, judge whether have intersection by described source node adjacent two internodal communication ranges of constant transmissions on each constant transmissions node to the transmission path of described tail node successively, if, do not perform step c, otherwise turn to down a pair adjacent constant transmissions node, repeat step b, to the last a pair adjacent constant transmissions node judges complete;

Step c, if communication range does not have the node be in before on described transmission path in adjacent two constant transmissions nodes of intersection to be first node, another node is Section Point, according to described Node distribution position, the mobile node that the message transmission time delay of described Section Point is minimum is found, using this mobile node as the first via node between described first node and described Section Point in the communication range of described first node;

Steps d, judge whether the communication range of described first via node and described Section Point has intersection, if having, turn to down a pair adjacent constant transmissions node, repeat step b, otherwise replace the described first node in step c with described first via node, repeat step c.

Further, the above-mentioned data transmission method based on track of vehicle also can have following characteristics, in step 5, describedly message to be comprised along described transmission node sequence transmission to described tail node:

In transmitting procedure, if the current mobile node carrying message runs into the new mobile node not in described transmission node sequence, and the message transmission time delay of the next stationary nodes of current mobile node is less than the message transmission time delay of described current mobile node to described next stationary nodes described in described new mobile node to described transmission node sequence, then described new mobile node is joined in described transmission node sequence, and give described new mobile node by transmission of messages.

Further, the above-mentioned data transmission method based on track of vehicle also can have following characteristics, in step 2, if the travel track of described object vehicle does not have stationary nodes, then search to be met with described object vehicle and can through the vehicle of stationary nodes as indirect object vehicle before meeting within the default time limit, replace described object vehicle with this indirect object vehicle, perform described step 3; Then through described step 5, the mobile node on described indirect object vehicle obtains message, also comprises after described step 5:

Step 6, message is transmitted to the mobile node on described object vehicle by the mobile node on described indirect object vehicle.

Further, the above-mentioned data transmission method based on track of vehicle also can have following characteristics, and in step 5, the mobile node that message is transmitted on described object vehicle by described tail node comprises:

After message arrives described tail node, if described object vehicle arrives in the communication range of described tail node, then message is directly sent to the mobile node on described object vehicle by described tail node, otherwise message is oppositely sent to the mobile node on described object vehicle by described tail node along the travel track of described object vehicle.

For solving the problems of the technologies described above, the invention allows for a kind of data transmission system based on track of vehicle, comprise be connected in turn module, judge module be set, search module, select module and transport module, wherein:

Module is set, for arranging mobile node on all vehicles, at partial intersection crossing, stationary nodes is set, at Network Access Point, source node is set, each mobile node, each stationary nodes and described source node all can calculate the message transmission time delay that self arrives arbitrary stationary nodes, and the travel track of place vehicle can be reported described source node by each mobile node in advance;

Judge module, during for needing at described source node to send message to object vehicle, whether the travel track judging described object vehicle having stationary nodes, if having, searches module described in starting;

Search module, last stationary nodes of message transfer is searched on the travel track at described object vehicle, be called tail node, described tail node meets: described source node is less than or equal to the advance time delay of described object vehicle to described tail node to the message transmission time delay of described tail node;

Select module, vehicle travel track for reporting according to each mobile node predicts each Node distribution position in each moment, described source node comprises stationary nodes and mobile node to the transmission node in the transmission node sequence of described tail node, described selection module is also for according to minimum message propagation delay time principle, and the message transmission time delay according to described Node distribution position and node selects described transmission node;

Transport module, for by message along described transmission node sequence transmission to described tail node, message is transmitted to the mobile node on described object vehicle by described tail node.

Further, the above-mentioned data transmission system based on track of vehicle also can have following characteristics, and described selection module comprises:

First selected cell, for selecting the stationary nodes in described transmission node sequence, is called constant transmissions node, makes by described source node minimum to total message transmission time delay of the transmission path of described tail node through each constant transmissions node;

First judging unit, for judging whether have intersection by described source node adjacent two internodal communication ranges of constant transmissions on each constant transmissions node to the transmission path of described tail node successively, if, do not start the second selected cell, otherwise turn to down a pair constant transmissions adjacent node, again start the first judging unit, to the last a pair adjacent constant transmissions node judges complete;

Second selected cell, if communication range does not have the node be in before on described transmission path in adjacent two constant transmissions nodes of intersection to be first node, another node is Section Point, second selected cell is used for according to described Node distribution position, the mobile node that the message transmission time delay of described Section Point is minimum is found, using this mobile node as the first via node between described first node and described Section Point in the communication range of described first node;

Second judging unit, for judging whether the communication range of described first via node and described Section Point has intersection, if have, turn to down a pair adjacent constant transmissions node, again start the first judging unit, otherwise replace described first node with described first via node, again start repetition second selected cell.

Further, the above-mentioned data transmission system based on track of vehicle also can have following characteristics, and described transport module comprises:

Updating block, for in transmitting procedure, if the current mobile node carrying message runs into the new mobile node not in described transmission node sequence, and the message transmission time delay of the next stationary nodes of current mobile node is less than the message transmission time delay of described current mobile node to described next stationary nodes described in described new mobile node to described transmission node sequence, described new mobile node is joined in described transmission node sequence, and gives described new mobile node by transmission of messages.

Further, the above-mentioned data transmission system based on track of vehicle also can have following characteristics, and described judge module comprises:

Search unit, when there is no stationary nodes on the travel track at described object vehicle, search to be met with described object vehicle and can through the vehicle of stationary nodes as indirect object vehicle before meeting within the default time limit, replace described object vehicle with this indirect object vehicle, described in startup, search module;

Then through the transmission of described transport module, the mobile node on described indirect object vehicle obtains message, and the described data transmission system based on track of vehicle also comprises

Forwarding module, for being transmitted to the mobile node on described object vehicle by the mobile node on described indirect object vehicle by message.

Further, the above-mentioned data transmission system based on track of vehicle also can have following characteristics, and described transport module comprises:

Direct retransmission unit, after arriving described tail node in message, if described object vehicle arrives in the communication range of described tail node, then direct mobile node message sent on described object vehicle;

Reverse delivery unit, after arriving described tail node in message, if described object vehicle does not arrive in the communication range of described tail node, then oppositely sends the mobile node on described object vehicle to along the travel track of described object vehicle by message.

Data transmission method based on track of vehicle of the present invention and system, be applicable to the infrastructure-to-vehicle data communication in VANET communication, by the stationary nodes in integration VANET and mobile node performance, and the computing capability utilizing node to possess, improve the validity and reliability of transfer of data.Meanwhile, because the present invention does not need to install stationary nodes in all intersections, therefore also greatly save construction and the maintenance cost of VANET network, thus effectively reduce transfer of data cost.

Accompanying drawing explanation

Fig. 1 is the flow chart of the embodiment of the present invention based on the data transmission method of track of vehicle;

Fig. 2 be in the embodiment of the present invention part stationary nodes cover under Internet access points to moving vehicle data transmission nodal model schematic;

Fig. 3 is embodiment of the present invention interior joint position prediction schematic diagram;

Fig. 4 is that in the embodiment of the present invention, transmission node upgrades flow chart;

Fig. 5 (a) is for running into transmission node sequence renewal example schematic during next node in transmission node sequence in the embodiment of the present invention;

Fig. 5 (b) is for running into the transmission node sequence renewal example schematic during new node not in transmission node sequence in the embodiment of the present invention;

Fig. 6 is the structured flowchart based on the data transmission system of track of vehicle in the embodiment of the present invention.

Embodiment

Be described principle of the present invention and feature below in conjunction with accompanying drawing, example, only for explaining the present invention, is not intended to limit scope of the present invention.

Fig. 1 is the flow chart of the embodiment of the present invention based on the data transmission method of track of vehicle.As shown in Figure 1, in the present embodiment, the data transmission method based on track of vehicle can comprise the steps:

Step S101, all vehicles arrange mobile node, arrange stationary nodes, arrange source node at Network Access Point at partial intersection crossing;

Each node (comprising each mobile node, each stationary nodes and source node) all can calculate the message transmission time delay that self arrives arbitrary stationary nodes.

The travel track of place vehicle can be reported source node by each mobile node in advance.Source node is Network Access Point AP, AP can be communicated with stationary nodes or mobile node by DSRC, and AP can be connected with traffic control center (TCC), when traffic control center needs to transmit message to certain vehicle, the message that self generates can be issued AP, issued the vehicle of receipt message by transmission node sequence by AP, the vehicle of receipt message is called object vehicle.

Owing to not needing all to arrange stationary nodes in all intersections, therefore greatly reduce construction and the maintenance cost of network, thus reduce the cost of transfer of data.

Node can be sensor device.All stationary nodes and mobile node are configured with GPS(GlobalPositioningSystem, global positioning system) device, have VANET magnitude of traffic flow statistics, possess computing ability.

GPS device can give the current location information of egress.All nodes in a VANET network have the magnitude of traffic flow statistics in each section.

All stationary nodes and mobile node can calculate message transmission time delay D from current location to a certain stationary nodes according to magnitude of traffic flow statistics.This time delay D can calculate with following formula (3).Below as nothing specializes, time delay all refers to message transmission time delay.

Vehicle can be described as by end-to-end time delay distribution g (v) of current location to target area (in transmission node sequence last stationary nodes)

V～Γ(κ _v,θ _v)， ${\mathrm{\κ}}_v=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\frac{{\left(E\right[v_i\left]\right)}^2}{\mathrm{Var}\left[v_i\right]},$ ${\mathrm{\θ}}_v=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}\frac{\mathrm{Var}\left[v_i\right]}{E\left[v_i\right]}$ Formula (1)

In formula (1), g (v) represents that vehicle is advanced along desired trajectory the distribution function of middle time delay variable V, k _v, θ _vrepresent two parameters of gamma, if total N section road, E [V _i], Var [V _i] be the expectation and variance that i-th (1≤i≤N) the section road gamma obtained according to statistical traffic data distributes, when the time delay distribution of g (v) meets gamma distribution, remember V ~ Γ (κ _v, θ _v).

Message comprises two parts from source node to the propagation delay time in a certain region, and namely each intersection all has the part of stationary nodes and each intersection not to have the part of stationary nodes.When there is a stationary nodes each intersection, propagation delay time is expected for E [P]:

$E\left[P\right]=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}(\frac{l_i-R-E\left[l_{f_i}\right]}{v_i}{\mathrm{\β}}_i+(\frac{1}{{\mathrm{\λ}}_i}+\frac{l_i-R}{v_i})(1-{\mathrm{\β}}_i))$ Formula (2)

In formula (2), if total two ends, N section section exist stationary nodes in message path, wherein the length of i-th (1≤i≤N) Duan Lu is l _i, vehicle operating average speed is v _i, the distance that message forwards transmission is message is β by the probability directly transmitted _i, the speed that vehicle arrives intersection is λ _i.

When each intersection distributes without stationary nodes, its time delay can be estimated with following formula (3).

$D=\underset{j=1}{\overset{M}{\mathrm{\Σ}}}(P_c*(C_{1j}+E_j))=\underset{j=1}{\overset{M}{\mathrm{\Σ}}}(\left(\underset{h=1}{\overset{j-1}{\mathrm{\Π}}}{P}_{h,h+1}^c\right)*(C_{1j}+\underset{k\∈N\left(j\right)}{\mathrm{\Σ}}{p}_{\mathrm{jk}}{D}_{\mathrm{jk}}))$ Formula (3)

In formula (3), D is from the source node current location of carrying message to the total time delay of a certain target area (fixed position) transmission of messages, M intersection is had along the travel track one of source node from source node to target area, each intersection is designated as j, 1≤j≤M, N(j) represent the neighbours intersection that crossing j is all, then a total M-1 bar section, remember that these sections are section h, 1≤h≤M-1.P _jkfor the probability that message forwards to these crossings at j, D _jkfor the overall delay to target area after message arrival crossing k, represent the time delay of message after crossing j forwards from Current vehicle; To each section h to h+1, represent and carry transmission probability, then the probability that message carries transmission from crossing 1 to crossing j along vehicle travel track is the total time that message carries transmission is C _1j.The travel track of source node is planned by source node, and after part of nodes reports the trace information of oneself to Internet access points, Internet access points also can obtain.Remainder data can obtain from magnitude of traffic flow statistics." ∑ " represents summation operation, and " ∏ " represents quadrature computing.

If total propagation delay time requires that (namely to the restriction of time delay) is TTL, total propagation delay time is EDD=E [P]+D when there is a stationary nodes intersection and when distributing without stationary nodes, can as message transmission time delay when meeting formula (4), that is:

EDD=E [P]+D≤TTL formula (4)

Step S102, when source node needs to send message to object vehicle, whether the travel track judging object vehicle has stationary nodes, if having, performs step S104, otherwise execution step S103;

In step S102, if source node prediction object vehicle can run into stationary nodes (that is object vehicle travel track having stationary nodes) on travel track, just according to the selection of following formula (5), last determines node admittedly.

$P_1={\∫}_0^{\mathrm{EDD}}g\left(v\right)\mathrm{dv}\≥\mathrm{\α}$ Formula (5)

In formula (5), α is the transmission success rate that user requires, g(v) to advance time delay distribution function for vehicle.

Step S103, source node is found and can be met setting in the time limit with object vehicle, and through the vehicle of stationary nodes, this vehicle can be called indirect object vehicle before meeting, replace real object vehicle (hereinafter referred to as direct object vehicle) with this indirect object vehicle, perform step S104;

If (that is object vehicle travel track does not have stationary nodes) when object vehicle travel track not existing stationary nodes, source node is found and can be met setting in the time limit with object vehicle, and can through the vehicle V of stationary nodes before meeting _j, meet following formula (6) and formula (7), by vehicle V simultaneously _jon mobile node as last message forward node.

$P_1={\∫}_0^{\mathrm{EDD}}g\left(v_j\right){\mathrm{dv}}_j\≥\mathrm{\α}$ Formula (6)

$P_2={\∫}_0^{\mathrm{TTL}}{\∫}_0^{v}g\left(v\right)g\left(v_j\right)\mathrm{dvd}{v}_j\≥\mathrm{\α}$ Formula (7)

Formula (6), in (7), g (v _j) be the selected object vehicle v of Internet access points _jtravel track time delay distribution function, same to formula (1), object vehicle v _jon mobile node message is forwarded to object vehicle (being namely transmitted to the mobile node on object vehicle).

That is, if object vehicle travel track does not have stationary nodes, just select an energy through the vehicle V of stationary nodes _j(vehicle V _jmeet: can meet setting in the time limit with object vehicle, and can through stationary nodes before meeting), by vehicle V _jas object vehicle, now just become situation object vehicle travel track having stationary nodes, according to this situation first select transmission node sequence by message according to this transmission node sequence transmission to vehicle V _j, then by vehicle V _jmessage is transmitted to object vehicle (vehicle sends and receipt message is all undertaken by the mobile node on vehicle).

Step S104, source node searches last stationary nodes of message transfer on the travel track of object vehicle, conveniently, this last stationary nodes is called tail node, and tail node meets following condition: source node is less than or equal to the advance time delay of object vehicle to tail node to the message transmission time delay of tail node;

Object vehicle refers to it is that object vehicle advances to the tail node time used to the time delay of advancing of tail node.

Tail node the condition that meets make message can be transferred to tail node before object vehicle reaches tail node, or be transferred to tail node while object vehicle reaches tail node, thus enable object vehicle receive message.

Step S105, each Node distribution position in vehicle travel track prediction each moment that source node reports according to each mobile node, source node comprises stationary nodes and mobile node to the transmission node in the transmission node sequence of described tail node, source node, according to minimum message propagation delay time principle, selects the transmission node in transmission node sequence according to the message transmission time delay of Node distribution position and node;

VANET network diagram G=(E can be passed through, I, S in each Node distribution position)) represent, wherein, E represents actual section, and I represents intersection, and S represents the stationary nodes being positioned at intersection.VANET network diagram is the basis that source node predicts certain moment Node distribution, there is the track that VANET network diagram and each mobile node report, Internet access points just can dope the Node distribution situation in each moment, thus finds out all transmission nodes, determines transmission node sequence.

When determining transmission node sequence, the track situation that source node reports according to each mobile node, VANET network node figure G=(E is built in real time according to time order and function order, I, S, V), V represents certain moment mobile node present position set that source node is predicted, as shown in Figure 3, be all Node distribution situations of a certain moment.Source node is such as set to 1 second every certain time interval t() transmission node of message transfer is selected according to this network node figure, determine a transmission node sequence from source node to tail node.

Particularly, in step S105, source node is according to minimum message propagation delay time principle, and the message transmission time delay according to Node distribution position and node selects the transmission node in transmission node sequence can comprise following step a to steps d:

Step a, selects the stationary nodes in transmission node sequence, is called constant transmissions node, makes by source node minimum to total message transmission time delay of the transmission path of tail node through each constant transmissions node;

Equaled the summation of the message transmission time delay in each section of path that this transmission path is separated by constant transmissions node to total message transmission time delay of the transmission path of tail node through each constant transmissions node by source node, wherein, the message transmission time delay in each section of path equals the message transmission time delay between the constant transmissions node at the two-end-point place being in this section of path.

Step b, judge whether have intersection by source node adjacent two internodal communication ranges of constant transmissions on each constant transmissions node to the transmission path of tail node successively, if, do not perform step c, otherwise turn to down a pair adjacent constant transmissions node, repeat step b, to the last a pair adjacent constant transmissions node judges complete;

Step c, if communication range does not have the node be in before on transmission path in adjacent two constant transmissions nodes of intersection to be first node, another node is Section Point, according to Node distribution position, the mobile node that the message transmission time delay of Section Point is minimum is found, using this mobile node as the first via node between first node and described Section Point in the communication range of first node;

Steps d, judges whether the communication range of the first via node and Section Point has intersection, if having, turns to down a pair adjacent constant transmissions node, repeats step b, otherwise replaces the first node in step c with the first via node, repeats step c.

The constant transmissions sequence node (being made up of constant transmissions nodes all in transmission node sequence) that source node finds is V _n=(v ₁, v ₂..., v _n).In source node to transmission node sequence, the time delay value of each stationary nodes is S _n=(s ₁, s ₂..., s _n).Wherein, S _nthe time delay value that source node arrives each stationary nodes, s _ibe the time delay value that source node arrives one of them stationary nodes, determine the time delay value from source node to stationary nodes, be in order in actual transmissions, pick out the transmission node that time delay value is lower.

Step S106, by message along the determined transmission node sequence transmission of step S105 to tail node;

In transmitting procedure, if carry the current mobile node v of message _irun into the new mobile node not in transmission node sequence, and current mobile node v in this new mobile node to transmission node sequence _ithe message transmission time delay D of next stationary nodes _newbe less than current mobile node v _ito the message transmission time delay of this next stationary nodes, then new mobile node is joined in transmission node sequence, and give new mobile node by transmission of messages.This new mobile node will be ensured to join after in transmission node sequence simultaneously, message to total time delay of next stationary nodes be less than add before by current mobile node v _ibe transferred to the overall delay of next stationary nodes.

Step S107, message is transmitted to the mobile node on object vehicle by tail node;

After message arrives last message forward node, if object vehicle just in time passes through last message forward node, then message is directly sent to object vehicle by last message forward node, if object vehicle not yet passes through last message forward node, then last message forward node oppositely sends message to object vehicle along the travel track of object vehicle.

Object vehicle in step S107 may be direct object vehicle, also may be indirect object vehicle.

Step S108, judges whether the object vehicle of receipt message is direct object vehicle, if then perform step S110, otherwise the object vehicle of receipt message is indirect object vehicle, performs step S109;

Step S109, message is transmitted to the mobile node on direct object vehicle by the mobile node on indirect object vehicle, then performs step S110;

Step S110, terminates.

Below in conjunction with concrete example, principle of the present invention is described further.

In the present embodiment, the node disposed in actual scene is divided into two classes, is deployed in the node at partial intersection crossing, is called stationary nodes; Be deployed in the node on moving vehicle, be called mobile node.Each node is MicaZ transducer, installs GPS device, possesses computing capability; Each mobile node can pass through VADD(Vehicle-AssistedDataDelivery, vehicle auxiliary data transmission), TBD(Trajectory-BasedDataForwarding, the data retransmission based on track) etc. mode the travel track of oneself is reported to access point AP.Each node has magnitude of traffic flow statistics and network model figure G=(E, I, S), E represents the set of actual section, I represents that intersection is gathered, S represents the stationary nodes set being positioned at each intersection, as shown in Figure 2, Fig. 2 be in the embodiment of the present invention part stationary nodes cover under Internet access points to moving vehicle data transmission nodal model schematic, in Fig. 2, SN represents stationary nodes, and MN represents mobile node, and AP represents linking Internet.Further, each node in illustraton of model G meets following rule:

The trace information of oneself can be passed to AP by rule 1. any mobile nodes, but not all node all transmits this message; AP can pass through DSRC(DedicatedShortRangeCommunications, very-short-reach communication, and transmission range is generally 200 meters) communicate with stationary nodes or mobile node, and AP directly can be connected with traffic control center (TCC).

Realize multi-hop communication by DSRC between rule 2. each nodes, wherein stationary nodes invariant position, can keep or forwarding messages, and positions of mobile nodes, according to the travel track change of oneself, can carry or forwarding messages.

Rule 3. calculates last node location two kinds of modes: one is, according to above-mentioned formula (5) $P_1={\∫}_0^{\mathrm{EDD}}g\left(v\right)\mathrm{dv}\≥\mathrm{\α},$ Two is meet above-mentioned formula (6) simultaneously $P_1={\∫}_0^{\mathrm{EDD}}g\left(v_j\right){\mathrm{dv}}_j\≥\mathrm{\α}$ With formula (7) $P_2={\∫}_0^{\mathrm{TTL}}{\∫}_0^{v}g\left(v\right)g\left(v_j\right)\mathrm{dvd}{v}_j\≥\mathrm{\α}$ Calculate.

When rule 4. determines transmission node sequence, the track situation that AP reports according to mobile node, builds network node figure G=(E in real time according to time order and function order, I, S, V), V represents certain moment mobile node present position set that AP predicts, as shown in Figure 3.Fig. 3 is embodiment of the present invention interior joint position prediction schematic diagram.In Fig. 3, dotted line represents the DSRC communication range of each node.AP can be set to 1 second every certain time interval t() select transmission node according to this node location figure, determine one from source node to the transmission node sequence V of last message forward node (for stationary nodes) _n=(v ₁, v ₂... v _n), and determine that in transmission node sequence, each transmission node is to the time delay S of each stationary nodes _n=(s ₁, s ₂..., s _n).

When rule 5. upgrades transmission node sequence, carry the mobile node v of message _iwhen often running into a neighbor node, if neighbor node is in transmission node sequence, be v _i+1, then directly transmit; If neighbor node, not in transmission node sequence, is new node v _new, then v _newcalculate v in transmission node sequence _ithe time delay value D of next stationary nodes _newif, D _new<D _i, then message is passed to new node, D _ifor present node v _ito the time delay value of next stationary nodes.

The source node of message is AP, and destination node is moving vehicle, and complete AP comprises to the transmitting procedure of moving vehicle:

Initial phase: when needing when there being message to send, AP reports track according to mobile node, calculates last message forward node (for stationary nodes) by above-mentioned rule 3, determines constant transmissions sequence node V by rule 4 _n=(v ₁, v ₂... v _n), and determine the time delay S of each constant transmissions node in AP to constant transmissions sequence node _n=(s ₁, s ₂..., s _n), complete initialization.

Data transfer phase: the present embodiment transfer sequence renewal process is with reference to figure 4, and transfer sequence interior joint renewal rewards theory is that in the embodiment of the present invention, transmission node upgrades flow chart with reference to figure 5, Fig. 4, and Fig. 5 is that in the embodiment of the present invention, transfer sequence upgrades example schematic.Dotted line in Fig. 3 represents DSRC transmission range, and all transmission ranges have the node of coincidence to be neighbor node, and update time is when running into new neighbor node.

As shown in Figure 4, in the present embodiment, in transmission node sequence, the renewal process of mobile node comprises the steps:

Step S401, present node (mobile node in transmission node sequence) runs into new neighbor node (neighbor node is mobile node), carries out node property judgement, if at transfer sequence, performs step S402, if not at transfer sequence, perform step S405;

Step S402, at transfer sequence;

Step S403, judges whether this new node (namely new in step S401 neighbor node) is next node in sequence (referring to transmission node sequence), if then perform step S404, otherwise performs step S405;

Step S404, transfers a message to this new node;

Step S405, not at transfer sequence;

Step S406, judges whether the time delay value of next stationary nodes in this new node to transmission node sequence is less than the time delay value of present node to next stationary nodes, if then perform step S407, otherwise performs step S408;

Step S407, transmits message to new node, performs step S409;

Step S408, does not process, and performs step S409;

Step S409, arrives last stationary nodes, i.e. tail node.

Step S401 is in step S409, and the node do not specialized all refers to mobile node.

Fig. 5 (a) is for running into transmission node sequence renewal example schematic during next node in transmission node sequence in the embodiment of the present invention.In Fig. 5 (a), 1. dotted line is message path, dotted line 2. for the purpose of vehicle travel track, v _ifor carrying the vehicle of message in transmitting procedure, v _i+1for next vehicle in the transfer sequence that the vehicle carrying message runs into, vehicle for the purpose of DN (DestinationNode), LSN (LastStationaryNode) is last stationary nodes.Fig. 5 (b) is for running into the transmission node sequence renewal example schematic during new node not in transmission node sequence in the embodiment of the present invention.In Fig. 5 (b), 3. dotted line is message path, dotted line 4. for the purpose of vehicle travel track, v _ifor carrying the vehicle of message in transmitting procedure, v _newfor the vehicle not in transmission node sequence that the vehicle carrying message runs into, vehicle for the purpose of DN, LSN is last stationary nodes.

First method according to the present invention will determine new neighbor node whether in transmission node sequence.With node v _ifor example, v _icarry message, the transmission node sequence V carried according to oneself _nwith time delay value S _nas basis for estimation, v _ito the time delay value D of next stationary nodes _ithe propagation delay time meeting i-th stationary nodes place message total is less than or equal to s _i.If v _iv is had in neighbor node _i+1, then directly to v _i+1pass-along message, completes and once upgrades, as shown in Fig. 5 (a); If there is no v in neighbor node _i+1, then calculate neighbor node to the time delay of next stationary nodes, therefrom select minimum time delay value D _newif, D _newbe less than the current time delay value D carrying information node _i, then this neighbor node becomes v _i, carry message, as shown in Fig. 5 (b).Until message arrives destination node, i.e. LSN in Fig. 5, then transmit to destination node DN.Complete process comprises:

1) current carry information node along Fig. 5 (a) center line 1. or Fig. 5 (b) center line 3. transmit, v _irun into and be arranged in transmission node sequence next node and v as shown in Fig. 5 (a) _i+1time, then directly pass and send a message to v _i+1.

2) if as shown in Fig. 5 (b), v _ithe node (one or more) run into is the node v do not had in transmission node sequence _new:

A) new node calculates the time delay D of next stationary nodes _newif, D _new>D _i, then the node v of message is carried _ido not do any operation.

If b) D _new<D _i, then by v _newadd transmission node sequence, message is by v _newcarry, become v _i.

3) message arrives last stationary nodes LSN in Fig. 5, then send message to destination node:

If a) last stationary nodes on node travel track for the purpose of LSN, then message to destination node travel track transmit in the other direction as Fig. 5 (a) center line 2. or Fig. 5 (b) center line opposite direction 4., message arrives destination node DN, completes transmission.

If b) LSN is destination node v _jlast stationary nodes on travel track, then message is first along v _jtravel track transmit in the other direction, arrive v _j, then by v _jmessage is sent to destination node DN in the other direction along destination node travel track, completes transmission.

Data transmission method based on track of vehicle of the present invention, be applicable to the infrastructure-to-vehicle data communication in VANET communication, by the stationary nodes in integration VANET and mobile node performance, and the computing capability utilizing node to possess, improve the validity and reliability of transfer of data.Meanwhile, because the present invention does not need to install stationary nodes in all intersections, therefore also greatly save construction and the maintenance cost of VANET network, thus effectively reduce transfer of data cost.

The invention allows for a kind of data transmission system based on track of vehicle, in order to perform the above-mentioned data transmission method based on track of vehicle.

Fig. 6 is the structured flowchart based on the data transmission system of track of vehicle in the embodiment of the present invention.As shown in Figure 6, in the present embodiment, the data transmission system based on track of vehicle comprise be connected in turn module 610, judge module 620 be set, search module 630, select module 640 and transport module 650.Wherein, module 610 is set, for arranging mobile node on all vehicles, at partial intersection crossing, stationary nodes is set, at Network Access Point, source node is set, each mobile node, each stationary nodes and described source node all can calculate the message transmission time delay that self arrives arbitrary stationary nodes, and the travel track of place vehicle can be reported described source node by each mobile node in advance.When judge module 620 is for needing at source node to send message to object vehicle, whether the travel track judging object vehicle has stationary nodes, if having, module 630 is searched in startup.Search last stationary nodes that module 630 searches message transfer on the travel track at object vehicle, be called tail node, tail node meets: source node is less than or equal to the advance time delay of object vehicle to tail node to the message transmission time delay of tail node.Module 640 is selected to predict each Node distribution position in each moment for the vehicle travel track reported according to each mobile node, source node comprises stationary nodes and mobile node to the transmission node in the transmission node sequence of tail node, select module 640 also for according to minimum message propagation delay time principle, select transmission node according to the Node distribution position of source node prediction and the message transmission time delay of node.Transport module 650 for by message along transmission node sequence transmission to tail node, message is transmitted to the mobile node on object vehicle by tail node.

In embodiments of the present invention, select to may further include the first selected cell, the first judging unit, the second selected cell and the second judging unit in module 640.First selected cell, for selecting the stationary nodes in transmission node sequence, is called constant transmissions node, makes by source node minimum to total message transmission time delay of the transmission path of tail node through each constant transmissions node.First judging unit is for judging whether have intersection by source node adjacent two internodal communication ranges of constant transmissions on each constant transmissions node to the transmission path of tail node successively, if, do not start the second selected cell, otherwise turn to down a pair adjacent constant transmissions node, again start the first judging unit, to the last a pair adjacent constant transmissions node judges complete.If communication range does not have the node be in before on transmission path in adjacent two constant transmissions nodes of intersection to be first node, another node is Section Point, second selected cell is used for according to Node distribution position, the mobile node that the message transmission time delay of Section Point is minimum is found, using this mobile node as the first via node between first node and Section Point in the communication range of first node.Second judging unit is for judging whether the communication range of the first via node and Section Point has intersection, if have, turn to down a pair adjacent constant transmissions node, again start the first judging unit, otherwise replace described first node with the first via node, again start repetition second selected cell.

In embodiments of the present invention, may further include updating block in transport module 650.Updating block is used in transmitting procedure, if the current mobile node carrying message runs into the new mobile node not in transmission node sequence, and the message transmission time delay of the next stationary nodes of current mobile node is less than the message transmission time delay of current mobile node to next stationary nodes in new mobile node to transmission node sequence, new mobile node is joined in transmission node sequence, and gives new mobile node by transmission of messages.

In embodiments of the present invention, may further include search unit in judge module 620.When search unit does not have a stationary nodes on the travel track at object vehicle, search to be met with object vehicle and can through the vehicle of stationary nodes as indirect object vehicle before meeting within the default time limit, replace object vehicle with this indirect object vehicle, start and search module 630.Then through the transmission of transport module 650, the mobile node on indirect object vehicle obtains message, and now, the data transmission system based on track of vehicle also comprises forwarding module.Forwarding module is for being transmitted to the mobile node on object vehicle by the mobile node on indirect object vehicle by message.

In embodiments of the present invention, may further include direct retransmission unit and reverse delivery unit in transport module 650.Direct retransmission unit is used for after message arrives tail node, if object vehicle arrives in the communication range of tail node, then and direct mobile node message sent on object vehicle.Reverse delivery unit is used for arriving after tail node in message, if object vehicle does not arrive in the communication range of tail node, then message is oppositely sent to the mobile node on object vehicle along the travel track of object vehicle.

Data transmission system based on track of vehicle of the present invention, be applicable to the infrastructure-to-vehicle data communication in VANET communication, by the stationary nodes in integration VANET and mobile node performance, and the computing capability utilizing node to possess, improve the validity and reliability of transfer of data.Meanwhile, because the present invention does not need to install stationary nodes in all intersections, therefore also greatly save construction and the maintenance cost of VANET network, thus effectively reduce transfer of data cost.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (8)

1. based on a data transmission method for track of vehicle, it is characterized in that, comprising:

Step one, all vehicles arrange mobile node, at partial intersection crossing, stationary nodes is set, at Network Access Point, source node is set, each mobile node, each stationary nodes and described source node all can calculate the message transmission time delay that self arrives arbitrary stationary nodes, and the travel track of place vehicle can be reported described source node by each mobile node in advance;

Step 2, when described source node needs to send message to object vehicle, whether the travel track judging described object vehicle has stationary nodes, if having, performs step 3; If the travel track of described object vehicle does not have stationary nodes, then search to be met with described object vehicle and can through the vehicle of stationary nodes as indirect object vehicle before meeting within the default time limit, replace described object vehicle with this indirect object vehicle, perform step 3;

Step 3, described source node searches last stationary nodes of message transfer on the travel track of described object vehicle or indirect object vehicle, be called tail node, described tail node meets: described source node to the message transmission time delay of described tail node be less than or equal to described object vehicle or indirectly object vehicle to the time delay of advancing of described tail node;

Step 4, the Node distribution position in vehicle travel track prediction each moment that described source node reports according to each mobile node, described source node comprises stationary nodes and mobile node to the transmission node in the transmission node sequence of described tail node, described source node is according to minimum message propagation delay time principle, and the message transmission time delay according to described Node distribution position and node selects described transmission node;

Step 5, by message along described transmission node sequence transmission to described tail node, message is transmitted to the mobile node on described object vehicle or indirect object vehicle by described tail node;

Step 6, when message is transmitted to indirect object vehicle by described tail node, message is transmitted to the mobile node on described object vehicle by the mobile node on described indirect object vehicle.

2. the data transmission method based on track of vehicle according to claim 1, it is characterized in that, in described step 4, described source node is according to minimum message propagation delay time principle, and the message transmission time delay according to described Node distribution position and node selects described transmission node to comprise:

Step a, selects the stationary nodes in described transmission node sequence, is called constant transmissions node, makes by described source node minimum to total message transmission time delay of the transmission path of described tail node through each constant transmissions node;

Step b, judge whether have intersection by described source node adjacent two internodal communication ranges of constant transmissions on each constant transmissions node to the transmission path of described tail node successively, if, do not perform step c, otherwise turn to down a pair adjacent constant transmissions node, repeat step b, to the last a pair adjacent constant transmissions node judges complete;

Step c, if communication range does not have the node be in before on described transmission path in adjacent two constant transmissions nodes of intersection to be first node, another node is Section Point, according to described Node distribution position, the mobile node that the message transmission time delay of described Section Point is minimum is found, using this mobile node as the first via node between described first node and described Section Point in the communication range of described first node;

Steps d, judge whether the communication range of described first via node and described Section Point has intersection, if having, turn to down a pair adjacent constant transmissions node, repeat step b, otherwise replace the described first node in step c with described first via node, repeat step c.

3. the data transmission method based on track of vehicle according to claim 1, is characterized in that, in step 5, describedly message to be comprised along described transmission node sequence transmission to described tail node:

In transmitting procedure, if the current mobile node carrying message runs into the new mobile node not in described transmission node sequence, and the message transmission time delay of the next stationary nodes of current mobile node is less than the message transmission time delay of described current mobile node to described next stationary nodes described in described new mobile node to described transmission node sequence, then described new mobile node is joined in described transmission node sequence, and give described new mobile node by transmission of messages.

4. the data transmission method based on track of vehicle according to claim 1, is characterized in that, in step 5, the mobile node that message is transmitted on described object vehicle by described tail node comprises:

After message arrives described tail node, if described object vehicle arrives in the communication range of described tail node, then message is directly sent to the mobile node on described object vehicle by described tail node, otherwise message is oppositely sent to the mobile node on described object vehicle by described tail node along the travel track of described object vehicle.

5., based on a data transmission system for track of vehicle, it is characterized in that, comprise be connected in turn module, judge module be set, search module, select module and transport module, wherein:

Module is set, for arranging mobile node on all vehicles, at partial intersection crossing, stationary nodes is set, at Network Access Point, source node is set, each mobile node, each stationary nodes and described source node all can calculate the message transmission time delay that self arrives arbitrary stationary nodes, and the travel track of place vehicle can be reported described source node by each mobile node in advance;

Judge module, during for needing at described source node to send message to object vehicle, whether the travel track judging described object vehicle having stationary nodes, if having, searches module described in starting; Described judge module comprises:

Search unit, when there is no stationary nodes on the travel track at described object vehicle, search to be met with described object vehicle and can through the vehicle of stationary nodes as indirect object vehicle before meeting within the default time limit, replace described object vehicle with this indirect object vehicle, described in startup, search module;

Search module, last stationary nodes of message transfer is searched on the travel track at described object vehicle or indirect object vehicle, be called tail node, described tail node meets: described source node to the message transmission time delay of described tail node be less than or equal to described object vehicle or indirectly object vehicle to the time delay of advancing of described tail node;

Select module, vehicle travel track for reporting according to each mobile node predicts each Node distribution position in each moment, described source node comprises stationary nodes and mobile node to the transmission node in the transmission node sequence of described tail node, described selection module is also for according to minimum message propagation delay time principle, and the message transmission time delay according to described Node distribution position and node selects described transmission node;

Transport module, for by message along described transmission node sequence transmission to described tail node, message is transmitted to described object vehicle or the mobile node indirectly on object vehicle by described tail node;

Forwarding module, for being transmitted to the mobile node on described object vehicle by the mobile node on described indirect object vehicle by message.

6. the data transmission system based on track of vehicle according to claim 5, is characterized in that, described selection module comprises:

First selected cell, for selecting the stationary nodes in described transmission node sequence, is called constant transmissions node, makes by described source node minimum to total message transmission time delay of the transmission path of described tail node through each constant transmissions node;

First judging unit, for judging whether have intersection by described source node adjacent two internodal communication ranges of constant transmissions on each constant transmissions node to the transmission path of described tail node successively, if, do not start the second selected cell, otherwise turn to down a pair adjacent constant transmissions node, again start described first judging unit, to the last a pair adjacent constant transmissions node judges complete;

Second selected cell, if communication range does not have the node be in before on described transmission path in adjacent two constant transmissions nodes of intersection to be first node, another node is Section Point, second selected cell is used for according to described Node distribution position, the mobile node that the message transmission time delay of described Section Point is minimum is found, using this mobile node as the first via node between described first node and described Section Point in the communication range of described first node;

Second judging unit, for judging whether the communication range of described first via node and described Section Point has intersection, if have, turn to down a pair adjacent constant transmissions node, again start the first judging unit, otherwise replace described first node with described first via node, again start and repeat described second selected cell.

7. the data transmission system based on track of vehicle according to claim 5, is characterized in that, described transport module comprises:

Updating block, for in transmitting procedure, if the current mobile node carrying message runs into the new mobile node not in described transmission node sequence, and the message transmission time delay of the next stationary nodes of current mobile node is less than the message transmission time delay of described current mobile node to described next stationary nodes described in described new mobile node to described transmission node sequence, described new mobile node is joined in described transmission node sequence, and gives described new mobile node by transmission of messages.

8. the data transmission system based on track of vehicle according to claim 5, is characterized in that, described transport module comprises:

Direct retransmission unit, after arriving described tail node in message, if described object vehicle arrives in the communication range of described tail node, then direct mobile node message sent on described object vehicle;

Reverse delivery unit, after arriving described tail node in message, if described object vehicle does not arrive in the communication range of described tail node, then oppositely sends the mobile node on described object vehicle to along the travel track of described object vehicle by message.