CN103338441A - Data transmission method and system based on vehicle track - Google Patents

Abstract

The invention relates to a data transmission method and a data transmission system based on vehicle tracks. The data transmission method based on vehicle tracks comprises steps that mobile nodes are disposed on all vehicles, fixed nodes are arranged at partial intersections, and a source node is arranged in a network access point; when the source node needs to send a message to a target vehicle, whether any fixed node exists on a progressing track of the target vehicle is determined; if any fixed node exists on the progressing track of the target vehicle, then the source node finds a tail node for message transmission on the progressing track of the target vehicle; the source node predicts every node distribution location at any moment according to the vehicle progressing tracks reported by every mobile node, and then according to the principle of minimum message transmission time delay, a transmission node sequence from the source node to the tail node is selected based on the node distribution location and the message transmission time delay of the node; the message is transmitted to the tail node along the transmission node sequence, and the tail node then forwards the message to the mobile node on the target vehicle. The data transmission method and the data transmission system based on vehicle tracks improve effectiveness and reliability of data transmission and at the same time effectively reduce data transmission cost.

Description

Data transmission method and system based on track of vehicle

Technical field

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

Background technology

Present VANET(Vehicular Ad-hoc Network, vehicle self-organizing network) infrastructure-to-vehicle(the Internet access point is to moving vehicle in) data transmission method mainly contains the infrastructure-to-vehicle transfer of data algorithm based on trajectory predictions that people such as Tian proposes, and proposed the infrastructure-to-vehicle data transfer mode based on purpose vehicle travel track first.This algorithm supposes that there is a stationary nodes each intersection, when having message to send, prediction destination node (being the mobile node on the purpose vehicle) is about to 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 probability maximization that arrives or just arrive.This algorithm has solved problems such as the big and success rate of infrastructure-to-vehicle propagation delay time shake is low, yet owing to need each intersection to install and fix node, bigger to VANET networking demand, maintenance cost is very high, its achievement in research is difficult in the reality and directly uses, and can not become the final effective means of dealing with problems.

Summary of the invention

Technical problem to be solved by this invention provides 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 1, at all vehicles mobile node is set, in the part intersection 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 self message transmission time delay to arbitrary stationary nodes, and each mobile node can be in advance reports described source node with the travel track of place vehicle;

Step 2 when described source node need send message to the purpose vehicle, judges on the travel track of described purpose vehicle whether stationary nodes is arranged, if then execution in step three is arranged;

Step 3, described source node is searched last stationary nodes of message transfer at the travel track of described purpose vehicle, be called tail node, described tail node satisfies: described source node is less than or equal to described purpose vehicle to the time delay of advancing of described tail node to the message transmission time delay of described tail node;

Step 4, each node distributing position constantly of vehicle travel track prediction 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 selected described transmission node according to minimum message propagation delay time principle according to the message transmission time delay of described node distributing position and node;

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

Further, above-mentioned data transmission method based on track of vehicle also can have following characteristics, in the described step 4, described message transmission time delay according to described each node distributing 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 the described transmission node sequence, is called the constant transmissions node, makes by described source node through the total message transmission time delay minimum of each constant transmissions node to the transmission path of described tail node;

Step b, judge successively by described source node and through each constant transmissions node adjacent two internodal communication ranges of constant transmissions to the transmission path of described tail node whether intersection is arranged, if there is not then execution in step c, otherwise turn to down a pair of adjacent fixed transmission node, repeating step b, a pair of adjacent fixed transmission node judgement to the last finishes;

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

Steps d, whether the communication range of judging described first via node and described Section Point has intersection, then turns to down a pair of adjacent fixed transmission node, repeating step b if having, otherwise with the described first node among described first via node replacement step c, repeating step c.

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

In the transmission course, run into the not new mobile node in described transmission node sequence if carry the current mobile node of message, and described new mobile node arrives the message transmission time delay of described next stationary nodes less than described current mobile node to the message transmission time delay of the next stationary nodes of current mobile node described in the described transmission node sequence, then described new mobile node is joined in the described transmission node sequence, and give described new mobile node with transmission of messages.

Further, above-mentioned data transmission method based on track of vehicle also can have following characteristics, in the step 2, if do not have stationary nodes on the travel track of described purpose vehicle, then the search meeting is being preset the vehicle conduct indirect purpose vehicle of preceding meeting through stationary nodes that meet and meet in the time limit with described purpose vehicle, replace described purpose vehicle with this indirect purpose vehicle, carry out described step 3; Then pass through described step 5, the mobile node on the described indirect purpose vehicle has obtained message, also comprises after the described step 5:

Step 6, the mobile node on the described indirect purpose vehicle is transmitted to mobile node on the described purpose vehicle with message.

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

After message arrives described tail node, if described purpose vehicle arrives in the communication range of described tail node, then described tail node directly sends to message the mobile node on the described purpose vehicle, otherwise described tail node oppositely sends message on the described purpose vehicle mobile node along the travel track of described purpose 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 in turn module, judge module are set, search module, select module and transport module of linking to each other, wherein:

Module is set, be used at all vehicles mobile node being set, in the part intersection 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 self message transmission time delay to arbitrary stationary nodes, and each mobile node can be in advance reports described source node with the travel track of place vehicle;

Judge module is used for when described source node need send message to the purpose vehicle, judges on the travel track of described purpose vehicle whether stationary nodes is arranged, and then starts the described module of searching if having;

Search module, for last stationary nodes of searching message transfer at the travel track of described purpose vehicle, be called tail node, described tail node satisfies: described source node is less than or equal to described purpose vehicle to the time delay of advancing of described tail node to the message transmission time delay of described tail node;

Select module, the vehicle travel track that is used for reporting according to each mobile node is predicted each each node distributing position constantly, 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 also is used for according to minimum message propagation delay time principle, selects described transmission node according to the message transmission time delay of described node distributing position and node;

Transport module is used for message along described transmission node sequence transmission to described tail node, and described tail node is transmitted to mobile node on the described purpose vehicle with message.

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

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

First judging unit, be used for judging successively by described source node and through each constant transmissions node adjacent two internodal communication ranges of constant transmissions to the transmission path of described tail node whether intersection arranged, if then do not start second selected cell, otherwise turn to down a pair of constant transmissions adjacent node, start first judging unit again, a pair of adjacent fixed transmission node judgement to the last finishes;

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

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

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

Updating block, be used in transmission course, run into the not new mobile node in described transmission node sequence if carry the current mobile node of message, and described new mobile node arrives the message transmission time delay of described next stationary nodes less than described current mobile node to the message transmission time delay of the next stationary nodes of current mobile node described in the described transmission node sequence, described new mobile node is joined in the described transmission node sequence, and give described new mobile node with transmission of messages.

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

Search unit, be used for when the travel track of described purpose vehicle does not have stationary nodes, the search meeting is being preset the vehicle conduct indirect purpose vehicle of preceding meeting through stationary nodes that meet and meet in the time limit with described purpose vehicle, replace described purpose vehicle with this indirect purpose vehicle, start the described module of searching;

Then pass through the transmission of described transport module, the mobile node on the described indirect purpose vehicle has obtained message, and described data transmission system based on track of vehicle also comprises

Forwarding module is used for message is transmitted to mobile node on the described purpose vehicle by the mobile node on the described indirect purpose vehicle.

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

Directly retransmission unit is used for after message arrives described tail node, if described purpose vehicle arrives in the communication range of described tail node, then directly message is sent to the mobile node on the described purpose vehicle;

Oppositely delivery unit is used for after message arrives described tail node, if in the communication range of the described tail node of described purpose vehicle no show, then oppositely sends message on the described purpose vehicle mobile node along the travel track of described purpose vehicle.

Data transmission method and system based on track of vehicle of the present invention, be applicable to the infrastructure-to-vehicle data communication in the VANET communication, by integrating stationary nodes and the mobile node performance among the VANET, and the computing capability of utilizing node to possess, improved validity and the reliability of transfer of data.Simultaneously, because the present invention need not install and fix node in all intersections, therefore also saved construction and the maintenance cost of VANET network greatly, thereby effectively reduced the transfer of data cost.

Description of drawings

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

Fig. 2 is that the Internet access point under the part stationary nodes covers in the embodiment of the invention is to moving vehicle data transmission nodal model schematic diagram;

Fig. 3 is node location prediction schematic diagram in the embodiment of the invention;

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

The transmission node sequence of Fig. 5 (a) when running into next node in the transmission node sequence in the embodiment of the invention upgraded example schematic;

The transmission node sequence of Fig. 5 (b) when running into the new node in the transmission node sequence not in the embodiment of the invention upgraded example schematic;

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

Embodiment

Below in conjunction with accompanying drawing principle of the present invention and feature are described, institute gives an actual example and only is used for explaining the present invention, is not for limiting scope of the present invention.

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

Step S101 arranges mobile node at all vehicles, in the part intersection stationary nodes is set, and at Network Access Point source node is set;

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

Each mobile node can be in advance reports source node with the travel track of place vehicle.Source node is Network Access Point AP, AP can communicate by letter with stationary nodes or mobile node by DSRC, and AP can be connected with traffic control center (TCC), when traffic control center need transmit message to certain vehicle, the message that self generates can be issued AP, issue the vehicle that receives message by AP by the transmission node sequence, the vehicle that receives message is called the purpose vehicle.

Owing to need stationary nodes all be set in all intersections, therefore greatly reduce construction and the maintenance cost of network, thereby reduced the cost of transfer of data.

Node can be sensor device.All stationary nodes and mobile node dispose GPS(Global Positioning System, global positioning system) device, have VANET magnitude of traffic flow statistics, possess the computing ability.

The GPS device can be given the current location information of egress.All nodes in a VANET network have the magnitude of traffic flow statistics in each highway 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 do not have and not specialize, time delay all refers to message transmission time delay.

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

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 the formula (1), g (v) represent vehicle advance along desired trajectory in the distribution function of time delay variable V, k _v, θ _vTwo parameters of expression gamma are established total N section road, E[V _i], Var[V _i] expectation and the variance that distribute for the section road gamma of the i(1≤i of obtaining according to statistical traffic data≤N), and g (when time delay distribution v) satisfies gamma and distributes, note V～Γ (κ _v, θ _v).

The propagation delay time of message from source node to a certain zone comprises two parts, and namely all there are the part of stationary nodes and the part that each intersection does not have stationary nodes in each intersection.When there was stationary nodes each intersection, the propagation delay time expectation was 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 the formula (2), establish in the message path total two ends, N section highway section and have stationary nodes, wherein the i(1≤i≤N) length of Duan Lu is l _i, vehicle operating average speed is v _i, the distance that message is transmitted transmission is

The probability that message is directly transmitted is β _i, the speed that vehicle arrives the intersection is λ _i

When each intersection did not have the stationary nodes distribution, 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 the formula (3), D for from the source node current location of carrying message to the total time delay of a certain target area (fixed position) transmission of messages, travel track one along source node from the source node to the target area has M intersection, each intersection is designated as j, 1≤j≤M, N(j) all neighbours intersections of expression crossing j, then a total M-1 bar highway section, remember that these highway sections are highway section h, 1≤h≤M-1.p _JkBe the probability that message is transmitted to these crossings at j, D _JkFor message arrives behind the k of crossing overall delay to the target area,

Expression message at crossing j from the time delay after vehicle in front forwarding; To each highway section h to h+1,

Transmission probability is carried in expression, and then 1 to the crossing j probability that carries transmission is message from the crossing along the vehicle travel track

The total time that message is carried transmission is C _1jThe travel track of source node is planned that by source node part of nodes reports the trace information of oneself behind the Internet access point, and the Internet access point also can obtain.Remainder data can obtain from magnitude of traffic flow statistics." ∑ " expression summation operation, " ∏ " expression quadrature computing.

If it be TTL that total propagation delay time requires the restriction of time delay (namely to), total propagation delay time is EDD=E[P when there is stationary nodes the intersection and during the distribution of no stationary nodes]+D, when satisfying formula (4), can be used as message transmission time delay, that is:

EDD=E[P]+D≤TTL formula (4)

Step S102 when source node need send message to the purpose vehicle, judges on the travel track of purpose vehicle whether stationary nodes is arranged, as if then execution in step S104 is arranged, otherwise execution in step S103;

Among the step S102, if source node prediction purpose vehicle can run into stationary nodes (that is to say that purpose vehicle travel track has stationary nodes) on travel track, just select to consolidate last according to following formula (5) and decide node.

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

In the formula (5), α is the transmission success rate of customer requirements, g(v) is the vehicle time delay distribution function of advancing.

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

If (not that is to say on the purpose vehicle travel track and do not have stationary nodes) when not having stationary nodes on the purpose vehicle travel track, source node is sought and can be met in the setting time limit with the purpose vehicle, and can be through the vehicle V of stationary nodes before meeting _j, satisfy following formula (6) and formula (7) simultaneously, with vehicle V _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)

${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA00003261481800021.png,HDA00003261481800041.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\&Integral;}_0^{\mathrm{TTL}}{\&Integral;}_0^{v}g\left(v\right)g\left(v_j\right)\mathrm{dvd}{v}_j\&GreaterEqual;\mathrm{\&alpha;}$ Formula (7)

Formula (6), in (7), g (v _j) be the purpose vehicle v that the Internet access point is selected _jTravel track time delay distribution function, same formula (1), purpose vehicle v _jOn mobile node message is forwarded to purpose vehicle (namely being transmitted to the mobile node on the purpose vehicle).

That is to say, if do not have stationary nodes on the purpose vehicle travel track, just select one can pass through the vehicle V of stationary nodes _j(vehicle V _jSatisfy: can in the setting time limit, meet with the purpose vehicle, and can pass through stationary nodes before meeting), with vehicle V _jAs the purpose vehicle, just become the situation that stationary nodes is arranged on the purpose vehicle travel track this moment, select the transmission node sequence to give vehicle V with message according to this transmission node sequence transmission earlier according to this situation _j, again by vehicle V _jMessage is transmitted to purpose vehicle (vehicle sends and receive message all to be undertaken by the mobile node on the vehicle).

Step S104, source node is searched last stationary nodes of message transfer at the travel track of purpose vehicle, for convenience, this last stationary nodes is called tail node, and tail node satisfies following condition: source node is less than or equal to the purpose vehicle to the time delay of advancing of tail node to the message transmission time delay of tail node;

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

The condition that tail node satisfied makes message can be transferred to tail node before the purpose vehicle reaches tail node, perhaps is transferred to tail node when the purpose vehicle reaches tail node, thereby makes the purpose vehicle can receive message.

Step S105, each each node distributing position constantly of vehicle travel track prediction 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 is according to minimum message propagation delay time principle, according to the transmission node in the message transmission time delay selection transmission node sequence of node distributing position and node;

Each node distributing position can pass through VANET network diagram G=(E, I, S)) expression, and wherein, E represents actual highway section, and I represents the intersection, and S represents to be positioned at the stationary nodes of intersection.The VANET network diagram is the basis that source node is predicted certain node distribution constantly, the track that has had VANET network diagram and each mobile node to report, the Internet access point just can dope each node distribution situation constantly, thereby finds out all transmission nodes, determines the transmission node sequence.

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

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

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

Equaled the summation of the message transmission time delay in each section path of being separated by the constant transmissions node on this transmission path 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 path equals to be in the constant transmissions messages between nodes propagation delay time at the two-end-point place in this section path.

Step b, judge successively by source node and through each constant transmissions node adjacent two internodal communication ranges of constant transmissions to the transmission path of tail node whether intersection is arranged, if there is not then execution in step c, otherwise turn to down a pair of adjacent fixed transmission node, repeating step b, a pair of adjacent fixed transmission node judgement to the last finishes;

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

Steps d judges whether the communication range of first via node and Section Point has intersection, if having and then turn to down a pair of adjacent fixed transmission node, and repeating step b, otherwise with the first node among first via node replacement step c, repeating step c.

The constant transmissions sequence node that source node finds (being made up of constant transmissions nodes all in the transmission node sequence) is V _n=(v ₁, v ₂..., v _n).Source node time delay value of each stationary nodes in the transmission node sequence is S _n=(s ₁, s ₂..., s _n).Wherein, S _nBe the time delay value that source node arrives each stationary nodes, s _iBeing the time delay value that source node arrives one of them stationary nodes, determining the time delay value from the source node to the stationary nodes, is in actual transmissions, picks out the lower transmission node of time delay value.

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

In the transmission course, if carry the current mobile node v of message _iRun into the not new mobile node in the transmission node sequence, and this new mobile node current mobile node v in the transmission node sequence _iThe message transmission time delay D of next stationary nodes _NewLess than current mobile node v _iMessage transmission time delay to this next one stationary nodes then joins new mobile node in the transmission node sequence, and gives new mobile node with transmission of messages.After will guaranteeing simultaneously should new mobile node to join in the transmission node sequence, message to total time-delay of next stationary nodes less than before adding by current mobile node v _iBe transferred to the overall delay of next stationary nodes.

Step S107, tail node is transmitted to mobile node on the purpose vehicle with message;

After message arrives last message forward node, if the purpose vehicle just in time passes through last message forward node, then last message forward node directly sends to message the purpose vehicle, if the purpose vehicle do not pass through last message forward node as yet, then last message forward node oppositely sends message to the purpose vehicle along the travel track of purpose vehicle.

Purpose vehicle among the step S107 may be direct purpose vehicle, also may be indirect purpose vehicle.

Step S108, whether the purpose vehicle that judge to receive message is direct purpose vehicle, if execution in step S110 then, otherwise the purpose vehicle that receives message is indirect purpose vehicle, execution in step S109;

Step S109, indirectly the mobile node on the purpose vehicle is transmitted to mobile node on the direct purpose vehicle, execution in step S110 then with message;

Step S110 finishes.

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

In the present embodiment, the node of disposing in the actual scene is divided into two classes, is deployed in the node of part intersection, be called stationary nodes; Be deployed in the node on the moving vehicle, be called mobile node.Each node is the MicaZ transducer, and GPS equipment is installed, and possesses computing capability; Each mobile node can pass through VADD(Vehicle-Assisted Data Delivery, the vehicle auxiliary data transmission), TBD(Trajectory-Based Data Forwarding, transmit based on the data of 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 highway section, I represents the intersection set, S represents to be positioned at the stationary nodes set of each intersection, as shown in Figure 2, Fig. 2 be in the embodiment of the invention the Internet access point under the covering of part stationary nodes to moving vehicle data transmission nodal model schematic diagram, among Fig. 2, SN represents stationary nodes, and MN represents mobile node, and AP represents the Internet and inserts.And each node among the illustraton of model G satisfies following rule:

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

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

Rule 3. is calculated last node location dual mode: the one, and, according to above-mentioned formula (5) $P_1={\&Integral;}_0^{\mathrm{EDD}}g\left(v\right)\mathrm{dv}\&GreaterEqual;\mathrm{\&alpha;},$ The 2nd, satisfy above-mentioned formula (6) simultaneously $P_1={\&Integral;}_0^{\mathrm{EDD}}g\left(v_j\right){\mathrm{dv}}_j\&GreaterEqual;\mathrm{\&alpha;}$ And formula (7) ${\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="HDA00003261481800021.png,HDA00003261481800041.png"\; state="\{\{state\}\}">P</figure-callout>}}_2={\&Integral;}_0^{\mathrm{TTL}}{\&Integral;}_0^{v}g\left(v\right)g\left(v_j\right)\mathrm{dvd}{v}_j\&GreaterEqual;\mathrm{\&alpha;}$ Calculate.

When rule 4. is determined the transmission node sequence, the track situation that AP reports according to mobile node, according to the time order and function order make up in real time network node figure G=(E, I, S, V), V represent that AP predicts certain gather mobile node present position constantly, as shown in Figure 3.Fig. 3 is node location prediction schematic diagram in the embodiment of the invention.Among Fig. 3, dotted line is represented 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 last message forward node the transmission node sequence V of (for stationary nodes) _n=(v ₁, v ₂... v _n), and in definite transmission node sequence each transmission node to the time-delay S of each stationary nodes _n=(s ₁, s ₂..., s _n).

When rule 5. is upgraded the transmission node sequence, carry the mobile node v of message _iDuring whenever to a neighbor node, if neighbor node in the transmission node sequence, is v _I+1, then directly transmit; If neighbor node not in the transmission node sequence, is new node v _New, v then _NewCalculate v in the transmission node sequence _iThe time delay value D of next stationary nodes _New, if D _New＜D _i, then message is passed to new node, D _iBe present node v _iTime delay value to next stationary nodes.

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

Initial phase: when message need send, AP reported track according to mobile node, calculated last message forward node (for stationary nodes) by above-mentioned rule 3, determined constant transmissions sequence node V by rule 4 _n=(v ₁, v ₂... v _n), and the time-delay S of definite AP each constant transmissions node in the constant transmissions sequence node _n=(s ₁, s ₂..., s _n), finish initialization.

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

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

Step S401, present node (mobile node in the transmission node sequence) run into new neighbor node (neighbor node is mobile node), carry out node character and judge, if at transfer sequence execution in step S402 then, if not at transfer sequence execution in step S405 then;

Step S402 is at transfer sequence;

Step S403 judges that whether this new node (being neighbor node new among the step S401) is next node in the sequence (referring to the transmission node sequence), if execution in step S404 then, otherwise execution in step S405;

Step S404 transfers a message to this new node;

Step S405 is not at transfer sequence;

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

Step S407 transmits message to new node, execution in step S409;

Step S408 does not process, execution in step S409;

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

Step S401 is to step S409, and the node that does not specialize all refers to mobile node.

The transmission node sequence of Fig. 5 (a) when running into next node in the transmission node sequence in the embodiment of the invention upgraded example schematic.Among Fig. 5 (a), 1. dotted line is message path, and 2. dotted line is purpose vehicle travel track, v _iFor carrying the vehicle of message, v in the transmission course _I+1Next vehicle in the transfer sequence that runs into for the vehicle that carries message, DN (Destination Node) is the purpose vehicle, LSN (Last Stationary Node) is last stationary nodes.The transmission node sequence of Fig. 5 (b) when running into the new node in the transmission node sequence not in the embodiment of the invention upgraded example schematic.Among Fig. 5 (b), 3. dotted line is message path, and 4. dotted line is purpose vehicle travel track, v _iFor carrying the vehicle of message, v in the transmission course _NewBe the not vehicle in the transmission node sequence that the vehicle that carries message runs into, DN is the purpose vehicle, and LSN is last stationary nodes.

The method according to this invention will determine at first that new neighbor node is whether in the transmission node sequence.With node v _iBe example, v _iCarry message, the transmission node sequence V that carries according to oneself _nWith time delay value S _nAs basis for estimation, v _iTime delay value D to next stationary nodes _iSatisfy and be less than or equal to s to i the stationary nodes place total propagation delay time of message _iIf v _iV is arranged in the neighbor node _I+1, then directly to v _I+1Pass-along message is finished once and is upgraded, shown in Fig. 5 (a); If do not have v in the 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 _NewLess than the current time delay value D that carries information node _i, then this neighbor node becomes v _i, carry message, shown in Fig. 5 (b).Arrive destination node up to message, namely LSN among Fig. 5 transmits to destination node DN again.Complete process comprises:

1) current carry information node along Fig. 5 (a) center line 1. or Fig. 5 (b) center line 3. transmit v _iRunning into and be arranged in transmission node sequence next node shown in Fig. 5 (a) is v _I+1The time, then directly transmit message to v _I+1

2) if shown in Fig. 5 (b), v _iThe node that runs into (one or more) is the node v that does not have in the transmission node sequence _New:

A) new node calculates the time delay D of next stationary nodes _New, if D _NewD _i, then carry the node v of message _iDo not do any operation.

B) if D _New＜D _i, then with v _NewAdd the transmission node sequence, message is by v _NewCarry, become v _i

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

A) if LSN is last stationary nodes on the destination node travel track, then as Fig. 5 (a) center line 2. or Fig. 5 (b) center line opposite direction 4. message transmit in the other direction to the destination node travel track, and message arrives destination node DN, finishes transmission.

B) if LSN is destination node v _jLast stationary nodes on the travel track, then message is earlier along v _jTravel track transmit in the other direction, arrive v _j, again by v _jMessage is sent to destination node DN in the other direction along the destination node travel track, finishes transmission.

Data transmission method based on track of vehicle of the present invention, be applicable to the infrastructure-to-vehicle data communication in the VANET communication, by integrating stationary nodes and the mobile node performance among the VANET, and the computing capability of utilizing node to possess, improved validity and the reliability of transfer of data.Simultaneously, because the present invention need not install and fix node in all intersections, therefore also saved construction and the maintenance cost of VANET network greatly, thereby effectively reduced the transfer of data cost.

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

Fig. 6 is based on the structured flowchart of the data transmission system of track of vehicle in the embodiment of the invention.As shown in Figure 6, in the present embodiment, comprise module 610, judge module 620 are set, search module 630, select module 640 and transport module 650 of linking to each other in turn based on the data transmission system of track of vehicle.Wherein, module 610 is set, be used at all vehicles mobile node being set, in the part intersection 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 self message transmission time delay to arbitrary stationary nodes, and each mobile node can be in advance reports described source node with the travel track of place vehicle.Judge module 620 is used for when source node need send message to the purpose vehicle, judges on the travel track of purpose vehicle whether stationary nodes is arranged, if there is then startup to search module 630.Search module 630 for last stationary nodes of searching message transfer at the travel track of purpose vehicle, be called tail node, tail node satisfies: source node is less than or equal to the purpose vehicle to the time delay of advancing of tail node to the message transmission time delay of tail node.Select module 640 to be used for each each the node distributing position constantly of vehicle travel track prediction that reports 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 to be used for according to minimum message propagation delay time principle, select transmission node according to the node distributing position of source node prediction and the message transmission time delay of node.Transport module 650 is used for message along the transmission node sequence transmission to tail node, and tail node is transmitted to mobile node on the purpose vehicle with message.

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

In embodiments of the present invention, may further include updating block in the transport module 650.Updating block is used in transmission course, run into the not new mobile node in the transmission node sequence if carry the current mobile node of message, and the message transmission time delay of new mobile node next stationary nodes of current mobile node in the transmission node sequence is less than the message transmission time delay of current mobile node to next stationary nodes, new mobile node is joined in the transmission node sequence, and give new mobile node with transmission of messages.

In embodiments of the present invention, may further include search unit in the judge module 620.Search unit is used for when the travel track of purpose vehicle does not have stationary nodes, the search meeting is being preset the vehicle conduct indirect purpose vehicle of preceding meeting through stationary nodes that meet and meet in the time limit with the purpose vehicle, replace the purpose vehicle with this indirect purpose vehicle, start and search module 630.Then pass through the transmission of transport module 650, indirectly the mobile node on the purpose vehicle has obtained message, at this moment, also comprises forwarding module based on the data transmission system of track of vehicle.Forwarding module is used for message is transmitted to mobile node on the purpose vehicle by the mobile node on the indirect purpose vehicle.

In embodiments of the present invention, may further include direct retransmission unit and reverse delivery unit in the transport module 650.Directly retransmission unit is used for after message arrives tail node, if the purpose vehicle arrives in the communication range of tail node, then directly message is sent to the mobile node on the purpose vehicle.Oppositely delivery unit is used for after message arrives tail node, if in the communication range of purpose vehicle no show tail node, then oppositely sends message on the purpose vehicle mobile node along the travel track of purpose vehicle.

Data transmission system based on track of vehicle of the present invention, be applicable to the infrastructure-to-vehicle data communication in the VANET communication, by integrating stationary nodes and the mobile node performance among the VANET, and the computing capability of utilizing node to possess, improved validity and the reliability of transfer of data.Simultaneously, because the present invention need not install and fix node in all intersections, therefore also saved construction and the maintenance cost of VANET network greatly, thereby effectively reduced the transfer of data cost.

The above only is preferred embodiment of the present invention, and is in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (10)

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

Step 1, at all vehicles mobile node is set, in the part intersection 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 self message transmission time delay to arbitrary stationary nodes, and each mobile node can be in advance reports described source node with the travel track of place vehicle;

Step 2 when described source node need send message to the purpose vehicle, judges on the travel track of described purpose vehicle whether stationary nodes is arranged, if then execution in step three is arranged;

Step 3, described source node is searched last stationary nodes of message transfer at the travel track of described purpose vehicle, be called tail node, described tail node satisfies: described source node is less than or equal to described purpose vehicle to the time delay of advancing of described tail node to the message transmission time delay of described tail node;

Step 4, each node distributing position constantly of vehicle travel track prediction 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 selected described transmission node according to minimum message propagation delay time principle according to the message transmission time delay of described node distributing position and node;

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

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

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

Step b, judge successively by described source node and through each constant transmissions node adjacent two internodal communication ranges of constant transmissions to the transmission path of described tail node whether intersection is arranged, if there is not then execution in step c, otherwise turn to down a pair of adjacent fixed transmission node, repeating step b, a pair of adjacent fixed transmission node judgement to the last finishes;

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

Steps d, whether the communication range of judging described first via node and described Section Point has intersection, then turns to down a pair of adjacent fixed transmission node, repeating step b if having, otherwise with the described first node among described first via node replacement step c, repeating step c.

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

In the transmission course, run into the not new mobile node in described transmission node sequence if carry the current mobile node of message, and described new mobile node arrives the message transmission time delay of described next stationary nodes less than described current mobile node to the message transmission time delay of the next stationary nodes of current mobile node described in the described transmission node sequence, then described new mobile node is joined in the described transmission node sequence, and give described new mobile node with transmission of messages.

4. the data transmission method based on track of vehicle according to claim 1, it is characterized in that, in the step 2, if do not have stationary nodes on the travel track of described purpose vehicle, then the search meeting is being preset the vehicle conduct indirect purpose vehicle of preceding meeting through stationary nodes that meet and meet in the time limit with described purpose vehicle, replace described purpose vehicle with this indirect purpose vehicle, carry out described step 3; Then pass through described step 5, the mobile node on the described indirect purpose vehicle has obtained message, also comprises after the described step 5:

Step 6, the mobile node on the described indirect purpose vehicle is transmitted to mobile node on the described purpose vehicle with message.

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

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

6. the data transmission system based on track of vehicle is characterized in that, comprises in turn module, judge module are set, search module, select module and transport module of linking to each other, wherein:

Module is set, be used at all vehicles mobile node being set, in the part intersection 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 self message transmission time delay to arbitrary stationary nodes, and each mobile node can be in advance reports described source node with the travel track of place vehicle;

Judge module is used for when described source node need send message to the purpose vehicle, judges on the travel track of described purpose vehicle whether stationary nodes is arranged, and then starts the described module of searching if having;

Search module, for last stationary nodes of searching message transfer at the travel track of described purpose vehicle, be called tail node, described tail node satisfies: described source node is less than or equal to described purpose vehicle to the time delay of advancing of described tail node to the message transmission time delay of described tail node;

Select module, the vehicle travel track that is used for reporting according to each mobile node is predicted each each node distributing position constantly, 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 also is used for according to minimum message propagation delay time principle, selects described transmission node according to the message transmission time delay of described node distributing position and node;

Transport module is used for message along described transmission node sequence transmission to described tail node, and described tail node is transmitted to mobile node on the described purpose vehicle with message.

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

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

First judging unit, be used for judging successively by described source node and through each constant transmissions node adjacent two internodal communication ranges of constant transmissions to the transmission path of described tail node whether intersection arranged, if then do not start second selected cell, otherwise turn to down a pair of adjacent fixed transmission node, start described first judging unit again, a pair of adjacent fixed transmission node judgement to the last finishes;

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

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

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

Updating block, be used in transmission course, run into the not new mobile node in described transmission node sequence if carry the current mobile node of message, and described new mobile node arrives the message transmission time delay of described next stationary nodes less than described current mobile node to the message transmission time delay of the next stationary nodes of current mobile node described in the described transmission node sequence, described new mobile node is joined in the described transmission node sequence, and give described new mobile node with transmission of messages.

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

Search unit, be used for when the travel track of described purpose vehicle does not have stationary nodes, the search meeting is being preset the vehicle conduct indirect purpose vehicle of preceding meeting through stationary nodes that meet and meet in the time limit with described purpose vehicle, replace described purpose vehicle with this indirect purpose vehicle, start the described module of searching;

Then pass through the transmission of described transport module, the mobile node on the described indirect purpose vehicle has obtained message, and described data transmission system based on track of vehicle also comprises

Forwarding module is used for message is transmitted to mobile node on the described purpose vehicle by the mobile node on the described indirect purpose vehicle.

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

Directly retransmission unit is used for after message arrives described tail node, if described purpose vehicle arrives in the communication range of described tail node, then directly message is sent to the mobile node on the described purpose vehicle;

Oppositely delivery unit is used for after message arrives described tail node, if in the communication range of the described tail node of described purpose vehicle no show, then oppositely sends message on the described purpose vehicle mobile node along the travel track of described purpose vehicle.

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