CN105682129A - Inter-vehicle communication transmission delay modeling method and device - Google Patents

Abstract

The invention provides an inter-vehicle communication transmission delay modeling method and device. The inter-vehicle communication transmission delay modeling method is characterized by comprising the following steps: transmitting data packets between a crossroad m and a crossroad n; computing a delay D according to the following formula (which is shown in the original PDF), wherein the d represents an expected data packet forwarding delay, the Pij represents the probability of Ii passing through an rij forwarding packet, and the N(j) represents a group of Ij neighboring crossroads. Compared with the prior art, the inter-vehicle communication transmission delay modeling method and device have the advantages that remoter-distance transmission delay can be computed under an inter-vehicle communication circumstance by improving an inter-vehicle communication transmission delay model, and a data packet forwarding strategy during interaction is determined by estimating the transmission delay, so that the efficiency of inter-vehicle communication is improved.

Description

Method and device for establishing inter-vehicle communication transmission delay model

Technical Field

The invention relates to the field of inter-vehicle communication, in particular to a method and a device for establishing an inter-vehicle communication transmission delay model.

Background

Vehicular ad hoc networks have great potential use in road security and many commercial applications, such as: and the driver is reminded of potential traffic jam, and emergency warning is transmitted to the driver to avoid collision accidents. Most current research on inter-vehicle communication is limited to single-hop or short-range multi-hop communication, but due to the limited broadcast range, only vehicles near the access point may receive data directly, which may be useful to people in distant vehicles. Data requests may be sent from miles or tens of miles away from the broadcast site, and through the vehicle ad hoc network, the requester may send a query to the broadcast site and get a reply, as long as some applications can tolerate a delay of seconds or even minutes. Although such services are currently available over wireless infrastructure (e.g., 3G networks), the cost of service providers to access the internet and the cost of handset users to access data is high, or such requests for information may not be available when the corresponding infrastructure is not present or damaged.

The high mobility of vehicles and the uneven density of vehicles in the temporal and spatial dimensions make multi-hop data transmission complex. For example, rural and nighttime traffic densities are low, and densely populated areas and rush hour traffic densities are high. In sparsely connected networks, end-to-end connectivity is difficult, while high mobility in-vehicle networks still provide mobile vehicles with intermittent connectivity opportunities while they are moving. In the highway model, it is highly likely that a moving vehicle will establish a short communication path of several hops, and a moving vehicle may carry data packets and forward to the next vehicle. By relaying, carrying and forwarding, certain delay-enabled applications can be delivered to the destination instead of over the end-to-end connection.

Vehicle-assisted inter-vehicle data transfer is based on the idea of carrying and forwarding, efficiently routing data packets to a destination and receiving replies within a reasonable delay. It is most important to select a forwarding path with the least packet forwarding delay. When the route does not exist, the node carries the packet; when a new receiver appears in its range, the node forwards the packet. Unlike existing carry and forward schemes, it takes advantage of the predictable and specific traffic patterns and road layout induced mobility characteristics of the on-board network. Therefore, there is a need to model effective packet forwarding delay based on vehicle mobility in real traffic patterns and road layout environments.

Disclosure of Invention

Therefore, a model for calculating the inter-vehicle communication transmission delay needs to be provided, and the problem of the application of the inter-vehicle communication transmission delay calculation is solved.

To achieve the above object, the inventor provides a method for establishing an inter-vehicle communication transmission delay model, which is characterized by comprising the following steps of transmitting data packets between intersections m and n, and calculating a delay D according to the following formula:

$D_{mn}=d_{mn}+\underset{j\∈N\left(n\right)}{\Σ}(P_{nj}\×D_{nj})$

where d is the expected packet forwarding delay, P_ijIs at I_iThrough r_ijA probability of forwarding a packet; n (j) is a group I_jThe adjacent crossing of the road is provided with a plurality of crossing lines,

d satisfies the following calculation:

$d_{ij}=(1-e^{-R\·{\mathrm{\ρ}}_{ij}})\·\frac{l_{ij}\·c}{R}+e^{-R\·{\mathrm{\ρ}}_{ij}}\·\frac{l_{ij}}{v_{ij}}$

wherein r is_ijIs from I_iTo I_jA path of (a); l_ijIs r_ijThe Euclidean distance of (c); rho_ijIs r_ijThe vehicle density of (a); v. of_ijIs r_ijThe vehicle average speed of (2); d_ijIs I_iTo I_jExpected packet forwarding delay; r refers to the radio transmission range and c refers to the average delay of a single-hop packet transmission.

Further, the method comprises the steps of sequencing the delay D of each adjacent intersection and forwarding the data packet along the path with the minimum delay, and specifically comprises sending the data packet to the automobile on the path with the minimum delay in all vehicles within the communication range available at the intersection.

Further, P_ijThe calculation method comprises the following steps:

$P_{ij}=\underset{c\∈N\left(i\right)}{\Σ}{Q}_{ic}\×p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}.$

$p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}=\left\{\begin{array}{cc}{P^{,}}_{{\mathrm{ij}}_p},& \&ForAll;p<c\\ 1-\underset{s=1}{\overset{c-1}{\mathrm{\&Sigma;}}}{P^{,}}_{{\mathrm{ij}}_s},& p=c\\ 0,& \&ForAll;p>c\end{array}\right.$

an inter-vehicle communication transmission delay model building device comprises a delay calculation module, wherein the delay calculation module is used for transmitting data packets between intersections m and n and calculating delay D according to the following formula:

$D_{mn}=d_{mn}+\underset{j\&Element;N\left(n\right)}{\&Sigma;}(P_{nj}\&times;D_{nj})$

where d is the expected packet forwarding delay, P_ijIs at I_iThrough r_ijA probability of forwarding a packet; n (j) is a group I_jThe adjacent crossing of the road is provided with a plurality of crossing lines,

d satisfies the following calculation:

$d_{ij}=(1-e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}})\&CenterDot;\frac{l_{ij}\&CenterDot;c}{R}+e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}}\&CenterDot;\frac{l_{ij}}{v_{ij}}$

wherein r is_ijIs from I_iTo I_jA path of (a); l_ijIs r_ijThe Euclidean distance of (c); rho_ijIs r_ijThe vehicle density of (a); v. of_ijIs r_ijThe vehicle average speed of (2); d_ijIs I_iTo I_jExpected packet forwarding delay; r refers to the radio transmission range and c refers to the average delay of a single-hop packet transmission.

Further comprises a data packet forwarding module,

the data packet forwarding module is used for sequencing the delay D of each adjacent intersection and forwarding the data packet along the path with the minimum delay;

it is also particularly useful for sending data packets to cars on the road with the least delay among all vehicles within the communication range available at the intersection.

Further, P_ijThe calculation method comprises the following steps:

$P_{ij}=\underset{c\&Element;N\left(i\right)}{\&Sigma;}{Q}_{ic}\&times;p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}.$

$p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}=\left\{\begin{array}{cc}{P^{,}}_{{\mathrm{ij}}_p},& \&ForAll;p<c\\ 1-{\mathrm{\&Sigma;}}_{s=1}^{c-1}{P^{,}}_{{\mathrm{ij}}_s},& p=c\\ 0,& \&ForAll;p>c\end{array}\right..$

different from the prior art, the technical scheme can calculate the transmission delay outside a longer distance under the scene of inter-vehicle communication by improving the inter-vehicle communication transmission delay model, and determines the data packet forwarding strategy during interaction by estimating the transmission delay, thereby improving the efficiency of inter-vehicle communication.

Drawings

Fig. 1 is a flowchart of a method for establishing an inter-vehicle communication transmission delay model according to an embodiment of the present invention;

FIG. 2 is a block diagram of an inter-vehicle communication transmission delay model building apparatus according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating an exemplary inter-vehicle communication transmission delay model according to an embodiment of the present invention;

FIG. 4 is a triangular via diagram according to an embodiment of the present invention;

fig. 5 is a diagram illustrating a known intra-boundary transmission according to an embodiment of the present invention.

Description of reference numerals:

200. a delay calculation module;

202. and a data packet forwarding module.

Detailed Description

To explain technical contents, structural features, and objects and effects of the technical solutions in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.

General idea

Inter-vehicle communication in a vehicle ad hoc network is based on carrying and forwarding, efficiently routing packets to destinations and receiving replies with a reasonable delay. When the route does not exist, the node carries the packet; when a new receiver appears in its range, the node forwards the packet.

While greedy boundary stateless routing (GPSR) of the geographical forwarding approach always selects the next hop closer to the destination, data transmission in ad hoc networks is quite efficient, but may not be well suited for sparsely connected vehicular networks. In sparse networks, vehicles should make best use of wireless communication, which is significantly faster than vehicles carry; if the vehicle is required to carry and transmit, the vehicle with higher moving speed is adopted as far as possible; due to the unpredictability of the vehicle-mounted ad hoc network, the data packet cannot be expected to be successfully forwarded along the pre-calculated optimal path, so that path selection must be continuously and dynamically performed in the whole data packet forwarding process.

Based on the above principle, the modeling of the inter-vehicle communication transmission delay of the vehicle assistance data requires separate modeling of the distance distribution between vehicles, the path distribution between the source and the destination, the path selection probability, and the like.

Detailed description of the invention

A. Preconditions

The establishment of the model requires that the vehicle communicates through a short-range wireless channel (100- & 250m) and carries specific information in the packet header: such as source ID, source location, packet generation time, destination location, expiration time, etc. The vehicle can know its position by triangulation or GPS, and attaches its own physical position, moving speed, direction information in periodic beacons, which can be acquired by their single-hop neighbor nodes. Meanwhile, vehicles are required to be equipped with a preloaded digital map, providing street maps and traffic statistics such as traffic density, speed of vehicles on roads at different times, and traffic signal schedules (e.g., length of red signal intervals) at intersections.

B. Construction of models

The packet forwarding delay is defined by the following symbols:

1)r_ij: from I_iTo I_jA path of (a);

2)l_ij:r_ijthe Euclidean distance of (c);

3)ρ_ij:r_ijthe vehicle density of (a);

4)v_ij:r_ijthe vehicle average speed of (2);

5)d_ij:I_ito I_jExpected packet forwarding delay.

Assuming that the distance between the vehicles follows an exponential distribution with an average distance equal to 1/p_ij. Then

$d_{ij}=(1-e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}})\&CenterDot;\frac{l_{ij}\&CenterDot;c}{R}+e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}}\&CenterDot;\frac{l_{ij}}{v_{ij}}---\left(1\right)$

Where R refers to the radio transmission range and c refers to the average delay of a single-hop packet transmission. Equation (1) refers to a portion where the distance between vehicles is less than RAnd the wireless transmission is adopted for the data packet forwarded in the part. On the rest of the roads, the vehicles need to carry data. Obviously, the greater the traffic density, the smaller the occupancy carried by the vehicle.

One way to view the inter-vehicle communication transmission delay model is to represent the on-board network with a directed graph, where nodes represent intersections and edges refer to roads connecting adjacent intersections. The direction of each edge is the direction of traffic. The packet forwarding delay between two adjacent intersections is the weight of an edge, and given the weight on each edge, the conventional optimal forwarding path selection scheme is to calculate the shortest path from the source to the destination by applying Dijkstra's algorithm. However, the intersection can not freely select the outward edge of the forwarding packet, and the traditional algorithm has the following defects that: only the edges of the vehicles used to carry the packets can be used as candidate paths for packet forwarding, but the direction to which the packet will go at the next intersection has no way to know that it is impossible to calculate the complete packet forwarding path.

The improved algorithm is as follows: a stochastic model is used to estimate the delay of the data transmission and thus to select the next road (intersection).

Referring to fig. 1, a flow chart of a method for establishing a transmission delay model for inter-vehicle communication according to the present invention is shown, which is characterized in that the method comprises a step S100 of transmitting data packets between intersections m and n, and calculating a delay D according to the following formula: the following symbols are defined:

1)D_ij: is coated with a carrier I_iSelect along the way r_ijTransfer packets, from I_iExpected packet delivery delay to the destination;

2)P_ij: in I_iThrough r_ijProbability of forwarding packets

3) N (j): group I_jAdjacent crossing of

In the embodiment shown in fig. 3, a method for calculating the inter-vehicle communication transmission delay in a limited number of intersections is shown. For in I_mA packet of (2), pass way r_mnThe expected delay for forwarding packets is:

D_mn＝d_mn+∑_j∈N(n)(P_nj×D_nj)(2)

FIG. 4 shows how (2) is applied to a road junction I containing only three intersections_a、I_b、I_cA simple triangle path. Suppose a packet arrives at I_aAnd end point is at I_c. The forwarding scheme needs to decide whether to forward to I via the path_cOr I_b. This is done by calculating D_acAnd D_abAnd the smaller is selected. By applying (2), the following linear equation is obtained:

$\left\{\begin{array}{c}{D}_{ac}=d_{ac}\\ D_{ab}=d_{ab}+P_{ba}\&CenterDot;D_{ba}+P_{bc}\&CenterDot;D_{bc}\\ D_{ba}=d_{ba}+P_{ab}\&CenterDot;D_{ab}+P_{ac}\&CenterDot;D_{ac}\\ D_{bc}=d_{bc}\\ D_{cb}=0\\ D_{ca}=0.\end{array}\right.---\left(3\right)$

note d_cbAnd d_caAre all 0 because the packet has reached destination I_cAnd is not forwarded any more. Can easily calculate (3) and obtain D_acAnd D_ab。

D_ac＝d_ac

$D_{ab}=\frac{1}{1-P_{ab}\&CenterDot;P_{ba}}\&times;(d_{ab}+P_{ba}\&CenterDot;d_{ba}+P_{ba}\&CenterDot;P_{ac}\&CenterDot;d_{ac}+P_{bc}\&CenterDot;d_{bc})$

In the embodiment shown in fig. 5, because infinite unknown intersections are involved, it is not possible to calculate the minimum forwarding delay between any two intersections, but by setting a boundary, including the connection graph of the source and destination, the expected minimum forwarding delay between them can be calculated. Fig. 5 shows one such boundary, including the sender and the destination (hot spot). Assume that the boundary used is a circle with the center at the destination. If the distance between the packet and the destination is less than 3000m, the circle radius is set to 4000 m; otherwise, the radius of the circle is the distance between the packet and the destination plus 1000 m. Of course, there are many other ways of setting the boundary, as long as the destination is included therein. Since only the roads within the boundary are used as available paths for computation delay, a boundary containing more streets in high density can usually find a path closer to the optimum, but with more computational overhead. Therefore, when selecting the boundary, a trade-off needs to be made between the computational complexity and accuracy of the delay estimation.

Since the number of intersections within the boundary is finite, one can deduce (2) the outward edges with respect to each intersection within the boundary [ similar to the method used for derivation (3) ], one can obtain an n × n linear system of equations, with n representing the number of ways within the boundary.

Following the general representation of a system of linear equations, the unknown D_ijRenamed as x_ijD is mixing_ijAnd x_ijRenames each pair ij a unique number, and assigns P_ijThe subscript of (a) is renamed according to its position in the equation, and can be deduced to contain n unknowns x₁，x₂，…，x_nN linear equations of

x₁＝d₁+P₁₁x₁+P₁₂x₂+…+P_1nx_n

x₁＝d₂+P₁₁x₁+P₂₂x₂+…+P_2nx_n

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x_n＝d_n+P_n1x₁+P_n2x₂+…+P_nnx_n

The following matrix is converted:

(P₁₁-1)x₁+P₁₂x₂+…+P_1nx_n＝-d₁

P₂₁x₁+(P₂₂-1)x₂+…+P_2nx_n＝-d₂

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P_n1x₁+P_n2x₂+…+(P_nn-1)x_n＝-d_n

is equivalent to (P-E). X ═ D (4)

Wherein, $X=\left[\begin{array}{c}{x}_1\\ x_2\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ x_n\end{array}\right],$ and $D=\left[\begin{array}{c}{d}_1\\ d_2\\ \&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\\ d_n\end{array}\right].$

the system of linear equations has a unique solution, and a typical method of solving this equation is to use a Gaussian elimination method whose time complexity is O (n)³)。

Obtaining the current intersection I by solving (4)_iD of (A)_ij. In the embodiment shown in fig. 1, the method further includes step S102 of sorting the delay D of each adjacent intersection and forwarding the data packet along the path with the smallest delay, specifically, sending the data packet to the car on the path with the smallest delay from all the vehicles in the communication range available at the intersection. Specifically, the packet carrier will be for each neighbor intersection I_jD of (A)_ijSort and forward packets along lower latency paths. Thus, in all vehicles within the communication range available at the intersection (called contact), the packet will be forwarded to cars on the road with the least delay. If there is no contact available, or if the path taken by all contacts is more delayed than the path taken by the packet carrier, the packet carrier will take the packet through this intersection and look for the next forwarding opportunity.

C. In I_iThrough r_ijProbability P of forwarding packets_ijIs calculated by

P_ijThe calculation method of (2) is very important. Temporary directional priority probing as a data transfer protocolThe protocol (the direction-first probing protocol strictly follows the priority of the direction for which the packet carrier will choose to forward contacts moving towards the selected direction. Other protocols may be modeled and calculated by similar methods.

It is assumed that each road has only one-way, two-way traffic, and that the intersection is a signal light intersection or an independent intersection, and that vehicles arriving at the intersection follow a poisson distribution.

The expected time a packet carrier stays in the intersection mode is called the contact time. At a signal lamp intersection I_iContact time of (d), denoted as t_iOnly with I_iThe length of the signal interval at (a) is related and assumed to be available from a digital map. At an independent intersection, vehicles in all directions can smoothly pass through without stopping. Suppose that the average vehicle speed across the intersection is the same as the average vehicle speed on the road leaving the intersection, and R is set_intThe intersection area is a circular area and the intersection point is the center of a circle. Equation (5) calculates the entry intersection I_iAnd go to adjacent crossing I_iContact time (T) of moving package carriers_ij)。

Only when the packet carrier encounters at least one of the directional paths r_ijThe package carrier can be in contact with the moving carrier at I_iIs located towards the road r_ijAnd (6) forwarding the packet. When the packet carrier enters the intersection region, it is calculated that it meets at least one path r_ijProbability of moving Contact (CP)_ij). Let N (T)_ij) Is shown at time interval T_ijInside, how much the intersection area can see towards the road r_ijMoving contact, and set λ_ijIndicates departure I_iAnd towards the road r_ijAverage rate of moving contact, i.e. λ_ij＝ρ_ij·v_ij(ρ_ij，v_ijAs defined above). According to the definition of poisson distribution:

$\begin{array}{c}{\mathrm{CP}}_{ij}=\mathrm{Pr}ob\left(N\right(T_{ij})\&GreaterEqual;1)\\ =1-\mathrm{Pr}ob\left(N\right(T_{ij})=0)\\ =1-e^{-{\mathrm{\&lambda;}}_{ij}{T}_{ij}}\frac{{\left({\mathrm{\&lambda;}}_{ij}{T}_{ij}\right)}^0}{0!}\\ =1-e^{-{\mathrm{\&rho;}}_{ij}{v}_{ij}{T}_{ij}}\end{array}$

if the intersection I_iWith only two outward paths r_iaAnd r_ibAnd satisfy D_ia<D_ibIn which the contact probability CP_iaAnd CP_ibRespectively, are in contact with the road r_iaAnd r_ibThe probability of contact. P_iaWill be equal to CP_ia，P_ibWill be equal to CP_ib-CP_ia·CP_ib. The purpose is that when the bag carrier passes through the intersection I_iIf both contacts are available, the path of the expected minimum propagation delay is selected. Therefore, I is to be calculated_iP of_ijWe need to first follow D_ijNon-decreasing order, for all CPs of j ∈ N (i)_ijAnd (6) sorting. However, D_ijNot available at this stage, we use way r_ijThe included angle between the direction of (1) and the vector from the current intersection to the destination is recorded as theta_ijFor approximating D_ij. This is because a smaller angled road is more likely to reach a location closer to the destination. CP (CP)_ijThe ordered list is as follows:

wherein n ═ n (i) messaging

j_iThe subscripts of (a) imply a meaningful order

${\mathrm{\&theta;}}_{{\mathrm{ij}}_1}\&le;{\mathrm{\&theta;}}_{{\mathrm{ij}}_2}\&le;{\mathrm{\&theta;}}_{{\mathrm{ij}}_3}\&le;...\&le;{\mathrm{\&theta;}}_{{\mathrm{ij}}_n}---\left(6\right)$

Using the underlying probabilities, a packet can be computed at I_iWay r_ijThe probability of forwarding. The result was designated as P'_ij。

${P^{,}}_{{\mathrm{ij}}_1}={\mathrm{CP}}_{{\mathrm{ij}}_1}$

${P^{,}}_{{\mathrm{ij}}_2}={\mathrm{CP}}_{{\mathrm{ij}}_2}-{\mathrm{CP}}_{{\mathrm{ij}}_1}\&CenterDot;{\mathrm{CP}}_{{\mathrm{ij}}_2}$

${P^{,}}_{{\mathrm{ij}}_3}={\mathrm{CP}}_{{\mathrm{ij}}_3}-({\mathrm{CP}}_{{\mathrm{ij}}_1}\&CenterDot;{\mathrm{CP}}_{{\mathrm{ij}}_3}+{\mathrm{CP}}_{{\mathrm{ij}}_2}\&CenterDot;{\mathrm{CP}}_{{\mathrm{ij}}_3})+{\mathrm{CP}}_{{\mathrm{ij}}_1}\&CenterDot;{\mathrm{CP}}_{{\mathrm{ij}}_2}\&CenterDot;{\mathrm{CP}}_{{\mathrm{ij}}_3}$

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If a carrier is passing through I_iWill go to the wayMoving (straight or turning) packets are only forwarded to higher or equal priority paths. That is, for one wayIf k is>c，Equal to 0, the packet bearer will buffer the data instead of forwarding it on to a lower priority way. Thus, the packet carrier leaves I_iTo the direction ofMoving, roadThe probability to be selected as the packet forwarding direction can be defined by the following conditional probability:

$p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}=\left\{\begin{array}{cc}{P^{,}}_{{\mathrm{ij}}_p},& \&ForAll;p<c\\ 1-{\mathrm{\&Sigma;}}_{s=1}^{c-1}{P^{,}}_{{\mathrm{ij}}_s},& p=c\\ 0,& \&ForAll;p>c\end{array}\right.---\left(7\right)$

let Q_icIndicating that a vehicle is passing through the current intersection I_iMove to the next adjacent crossing I_cProbability of (straight or turning). P_ijCan be calculated by:

$P_{ij}={\mathrm{\&Sigma;}}_{c\&Element;N\left(i\right)}{Q}_{ic}\&times;p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}.---\left(8\right)$

the accuracy of estimating the transmission delay by the inter-vehicle communication can be effectively improved by substituting the calculation result into the formula (2), and the inter-vehicle communication transmission delay model is further improved by applying the transmission probability calculation method.

Referring to fig. 2, the device for establishing a model of inter-vehicle communication transmission delay comprises a delay calculation module 200, wherein the delay calculation module 200 is used for transmitting data packets between intersections m and n, and calculating the delay D according to the following formula:

$D_{mn}=d_{mn}+\underset{j\&Element;N\left(n\right)}{\&Sigma;}(P_{nj}\&times;D_{nj})$

where d is the expected packet forwarding delay, P_ijIs at I_iThrough r_ijA probability of forwarding a packet; n (j) is a group I_jThe adjacent crossing of the road is provided with a plurality of crossing lines,

d satisfies the following calculation:

$d_{ij}=(1-e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}})\&CenterDot;\frac{l_{ij}\&CenterDot;c}{R}+e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}}\&CenterDot;\frac{l_{ij}}{v_{ij}}$

wherein r is_ijIs from I_iTo I_jA path of (a); l_ijIs r_ijThe Euclidean distance of (c); rho_ijIs r_ijThe vehicle density of (a); v. of_ijIs r_ijThe vehicle average speed of (2); d_ijIs I_iTo I_jExpected packet forwarding delay; r refers to the radio transmission range and c refers to the average delay of a single-hop packet transmission.

In a further embodiment, the apparatus further comprises a packet forwarding module 202,

the packet forwarding module 202 is configured to sort the delays D of each adjacent intersection and forward the packet along the path with the smallest delay;

it is also particularly useful for sending data packets to cars on the road with the least delay among all vehicles within the communication range available at the intersection.

Further, P_ijThe calculation method comprises the following steps:

$P_{ij}=\underset{c\&Element;N\left(i\right)}{\&Sigma;}{Q}_{ic}\&times;p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}.$

$p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}=\left\{\begin{array}{cc}{P^{,}}_{{\mathrm{ij}}_p},& \&ForAll;p<c\\ 1-{\mathrm{\&Sigma;}}_{s=1}^{c-1}{P^{,}}_{{\mathrm{ij}}_s},& p=c\\ 0,& \&ForAll;p>c\end{array}\right..$

different from the prior art, the device can calculate the transmission delay outside a longer distance under the scene of inter-vehicle communication by improving the inter-vehicle communication transmission delay model, determines the data packet forwarding strategy during interaction by estimating the transmission delay, and improves the efficiency of inter-vehicle communication.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrases "comprising … …" or "comprising … …" does not exclude the presence of additional elements in a process, method, article, or terminal that comprises the element. Further, herein, "greater than," "less than," "more than," and the like are understood to exclude the present numbers; the terms "above", "below", "within" and the like are to be understood as including the number.

As will be appreciated by one skilled in the art, the above-described embodiments may be provided as a method, apparatus, or computer program product. These embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. All or part of the steps in the methods according to the embodiments may be implemented by a program instructing associated hardware, where the program may be stored in a storage medium readable by a computer device and used to execute all or part of the steps in the methods according to the embodiments. The computer devices, including but not limited to: personal computers, servers, general-purpose computers, special-purpose computers, network devices, embedded devices, programmable devices, intelligent mobile terminals, intelligent home devices, wearable intelligent devices, vehicle-mounted intelligent devices, and the like; the storage medium includes but is not limited to: RAM, ROM, magnetic disk, magnetic tape, optical disk, flash memory, U disk, removable hard disk, memory card, memory stick, network server storage, network cloud storage, etc.

The various embodiments described above are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a computer apparatus to produce a machine, such that the instructions, which execute via the processor of the computer apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer device to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer apparatus to cause a series of operational steps to be performed on the computer apparatus to produce a computer implemented process such that the instructions which execute on the computer apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Although the embodiments have been described, once the basic inventive concept is obtained, other variations and modifications of these embodiments can be made by those skilled in the art, so that the above embodiments are only examples of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes using the contents of the present specification and drawings, or any other related technical fields, which are directly or indirectly applied thereto, are included in the scope of the present invention.

Claims (6)

1. A method for establishing an inter-vehicle communication transmission delay model is characterized by comprising the following steps of transmitting data packets between intersections m and n, and calculating delay D according to the following formula:

$D_{mn}=d_{mn}+\underset{j\&Element;N\left(n\right)}{\&Sigma;}(P_{nj}\&times;D_{nj})$

where d is the expected packet forwarding delay, P_ijIs at I_iThrough r_ijA probability of forwarding a packet; n (j) is a group I_jThe adjacent crossing of the road is provided with a plurality of crossing lines,

d satisfies the following calculation:

$d_{ij}=(1-e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}})\&CenterDot;\frac{l_{ij}\&CenterDot;c}{R}+e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}}\&CenterDot;\frac{l_{ij}}{v_{ij}}$

wherein r is_ijIs from I_iTo I_jA path of (a); l_ijIs r_ijThe Euclidean distance of (c); rho_ijIs r_ijThe vehicle density of (a); v. of_ijIs r_ijThe vehicle average speed of (2); d_ijIs I_iTo I_jExpected packet forwarding delay; r refers to the radio transmission range and c refers to the average delay of a single-hop packet transmission.

2. The method of claim 1, further comprising the steps of sequencing the delays D for each adjacent intersection and forwarding the data packets along the least delayed path, including in particular sending the data packets to cars on the least delayed path, among all vehicles within the communication range available at the intersection.

3. The inter-vehicle communication transmission delay model creation method according to claim 1, wherein P is_ijThe calculation method comprises the following steps:

$P_{ij}=\underset{c\&Element;N\left(i\right)}{\&Sigma;}{Q}_{ic}\&times;p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}.$

$p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}=\left\{\begin{array}{cc}{P^{,}}_{{\mathrm{ij}}_p},& \&ForAll;p<c\\ 1-{\mathrm{\&Sigma;}}_{s=1}^{c-1}{P^{,}}_{{\mathrm{ij}}_s},& p=c\\ 0,& \&ForAll;p>c\end{array}\right..$

4. an inter-vehicle communication transmission delay model building device is characterized by comprising a delay calculation module, wherein the delay calculation module is used for transmitting data packets between intersections m and n and calculating delay D according to the following formula:

$D_{mn}=d_{mn}+\underset{j\&Element;N\left(n\right)}{\&Sigma;}(P_{nj}\&times;D_{nj})$

where d is the expected packet forwarding delay, P_ijIs at I_iThrough r_ijA probability of forwarding a packet; n (j) is a group I_jAdjacent road ofThe mouth of the patient is provided with a mouth,

d satisfies the following calculation:

$d_{ij}=(1-e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}})\&CenterDot;\frac{l_{ij}\&CenterDot;c}{R}+e^{-R\&CenterDot;{\mathrm{\&rho;}}_{ij}}\&CenterDot;\frac{l_{ij}}{v_{ij}}$

wherein r is_ijIs from I_iTo I_jA path of (a); l_ijIs r_ijThe Euclidean distance of (c); rho_ijIs r_ijThe vehicle density of (a); v. of_ijIs r_ijThe vehicle average speed of (2); d_ijIs I_iTo I_jExpected packet forwarding delay; r refers to the radio transmission range and c refers to the average delay of a single-hop packet transmission.

5. The inter-vehicle communication transmission delay model creation device according to claim 4, further comprising a packet forwarding module,

the data packet forwarding module is used for sequencing the delay D of each adjacent intersection and forwarding the data packet along the path with the minimum delay;

it is also particularly useful for sending data packets to cars on the road with the least delay among all vehicles within the communication range available at the intersection.

6. The inter-vehicle communication transmission delay model creation device according to claim 4, wherein P is P_ijThe calculation method comprises the following steps:

$P_{ij}=\underset{c\&Element;N\left(i\right)}{\&Sigma;}{Q}_{ic}\&times;p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}.$

$p_{{\mathrm{ij}}_p|{\mathrm{ij}}_c}=\left\{\begin{array}{cc}{P^{,}}_{{\mathrm{ij}}_p},& \&ForAll;p<c\\ 1-{\mathrm{\&Sigma;}}_{s=1}^{c-1}{P^{,}}_{{\mathrm{ij}}_s},& p=c\\ 0,& \&ForAll;p>c\end{array}\right..$