CN102098230B - Resource scheduling method based on time and space correlation in vehicle communication - Google Patents

Abstract

The invention discloses a resource scheduling method based on time and space correlation in vehicle communication, which is used for mainly solving the problem of high resource collision probability caused by simultaneous channel competition of different priorities of resources in the traditional vehicle communication network during the distribution. The resource scheduling method comprises the steps of: 1, establishing a resource attribute data packet; 2, sending the resource attribute data packet; 3, checking whether the data packet exists or not; 4, judging whether resources meet the condition of received resources or not; and 5, calculating the correlation and receiving the resources. Aiming at different resource setting priorities, the invention ensures that the resources being high in urgent degree and important in vehicle users can be preferentially transmitted. In a process of receiving the resources, the defect of high resource collision rate caused by the adoption of a random switching manner is overcome according to a method for receiving correlation function values in a descending order by adopting a time and space correlation function. According to the invention, the problem of the dynamic priority change is solved in the process of propagating the resources.

Description

In the vehicle communication based on the resource regulating method of time and spatial coherence

Technical field

The present invention relates to communication technical field, further relate to a kind of time of resource and the method that spatial coherence is realized scheduling of resource utilized in the vehicle wireless communication field.This method realizes transmission and the reception of different priorities resource in the vehicle communication network, can be used as important component part of intelligent traffic control system.

Background technology

In recent years, along with the explosive growth of vehicle and ubiquitous information requirement, the communication service demand of people in the vehicle moving process increases day by day, and vehicle mobile network's research has become the focus of attracting attention in the world, also promoted vehicle to development intelligent, networked direction simultaneously.

People such as Bo Xu are at document " Opportunistic Resource Exchange in Inter-vehicle Ad-hoc Networks ", Proceedings of the 2004 IEEE International Conference on Mobile Data Management (MDM ' 04), 0-7695-2070-7/04$20.00.2004IEEE, the method that a kind of resource-based time and spatial coherence are realized inquiry and the storage of resource has been proposed.This method has realized effective storage and the renewal of resource in limited memory space, can realize resource discovering than faster simultaneously.This method according to " correlation " of resource descending sequential storage in internal memory.When internal memory is filled with, when having new resource to arrive again, recomputate the relevance function value of all resources in the internal memory, being eliminated of correlation minimum, new resources are saved.Because this method only relates to the discovery of resource, for the distribution of resource, then exchange with at random mode, the resource collision takes place a plurality of resources being arranged simultaneously during competitive channel in this method easily.Simultaneously, owing to not to resource settings priority, can not satisfy the user to the different demands of the different resource of urgency level.

Summary of the invention

The objective of the invention is to overcome the deficiency of above-mentioned technology, propose a kind of resource regulating method based on time and spatial coherence, to transmission and the reception of different priorities resource, reduce the probability of resource collision in the realization vehicle communication network.

The step that the present invention realizes comprises as follows:

(1) sends vehicle foundation and resource " Resource Properties " packet one to one;

(2) " Resource Properties " packet is sent to the reception vehicle by wireless channel;

Whether (3) receive the vehicle inspection packet and exist in memory headroom, if exist, then reject resource, transmission course finishes; If do not exist, then carry out step (4);

(4) by " Resource Properties " packet, judge that whether resource satisfies the condition that is received, if satisfy, then carries out step (5); If do not satisfy, then rejection, transmission course finishes;

(5) receive resource: if having only a resource to wait to receive, then directly receive resource; If have a plurality of resources to need simultaneously to receive, then carry out step 5a) and 5b);

5a) calculate relevance function value F (R)

$\left\{\begin{array}{cc}F\left(R\right)={\mathrm{\α}}_j\·t+{\mathrm{\β}}_j\·d+{\mathrm{\γ}}_j& ({\mathrm{\α}}_j\≤0,{\mathrm{\β}}_j\≤0)\\ d={[{(x_i-x_0)}^2+{(y_i-y_0)}^2]}^{\frac{1}{2}}& \\ t=t_i-t_0& \end{array}\right.$

Wherein: t is the moment t that vehicle receives packet _iProduce t constantly to resource ₀The time interval;

Position (x when d is vehicle reception packet _i, y _i) produce ground (x to resource ₀, y ₀) distance;

α _j, β _j, γ _jBe constant, α _j, β _jRepresent time interval t respectively and apart from the decay factor of d, γ _jBe the priority regulatory factor; α _j, β _j, γ _jThe size of numerical value is called according to the kind j of resource;

5b) queuing: rank according to the order that the relevance function value is descending, receive resource successively.

Compared with prior art, the present invention has the following advantages:

The first, because the present invention when receiving resource successively, adopts the method at different resource settings priority, make can access prioritised transmission to the vehicle user important resource by the urgency level height, satisfy the needs of different user.

The second, because the present invention adopts the temporal correlation function in the resource receiving course, by the method for the descending order reception of relevance function value, overcome that prior art adopts exchanged form at random and the high shortcoming of resource collision rate that causes.

The 3rd, the present invention is in the resource receiving course, though to the resource settings of different urgency levels priority, but in the communication process of reality, be not to receive according to priority order from high to low, but adopt the method that receives according to the descending order of relevance function value, solved resource in communication process, because of the problem that the duration increases and the propagation distance increase causes the reduction of resource urgency level, actual priority to reduce, can better satisfy user's actual needs.

Description of drawings

Fig. 1 is flow chart of the present invention

Fig. 2 is priority regulatory factor γ of the present invention _jThe establishing method key diagram

Embodiment

The present invention will be further described below in conjunction with accompanying drawing 1:

Step 1 is set up " Resource Properties " packet.Send vehicle with the place (x of the initial generation of resource ₀, y ₀), time t ₀, classification j, the user u that produces this resource set up " Resource Properties " packet (x ₀, y ₀, t ₀, j, u).Resource can with space correlation, time correlation or temporal and spatial correlations, so the Resource Properties of different resource also is different.With the resource of time correlation as " stock information in some time ", its form is (t ₀, j, u); With the resource of space correlation as " positional information of gas station ", its form is (x ₀, y ₀, j, u); With the resource of temporal and spatial correlations as " traffic accident takes place in the some time somewhere ", its form is (x ₀, y ₀, t ₀, j, u).Each resource is one to one with " Resource Properties " packet.To have amount of information little for " Resource Properties " packet of Jian Liing thus, and channel resource is taken few characteristics.

Step 2 sends " Resource Properties " packet.Send vehicle before sending resource, " Resource Properties " packet with this resource sends to the reception vehicle by wireless channel earlier.

Step 3 checks whether packet exists.Receive vehicle by check whether " Resource Properties " packet exists, and can learn whether this resource received in memory headroom.If exist, then reject resource, transmission course finishes.Can avoid the reception that repeats to same resource like this, reduce the waste to channel resource; If do not exist, then carry out step (4) reception vehicle and judge further whether resource satisfies the condition that is received.

Step 4 judges whether resource satisfies the condition that is received.Because the finiteness of channel resource, the propagation of resource needs to set certain boundary in duration and spread scope.Beyond the mark, resource can not be sent out or receive.Resource is propagated boundary, set according to actual conditions (resource coverage, effective time etc.).As: " traffic lights at certain crossing of some time is red light " this information need not be propagated the vehicle to entire city, as long as allow the interior vehicle of this crossing 1 km left and right sides scope know, can allow vehicle in time adjust and get final product.Simultaneously, because the red light duration is shorter, generally at 30-60 between second, if the time of reception is oversize to the time at intervals that this information produces, this information has lost value concerning vehicle user, so its event horizon can be arranged on 20-40 between second.

By " Resource Properties " packet, judge whether to satisfy time domain and spatial domain restrictive condition.If satisfy, then carry out step (5); If do not satisfy, then rejection, transmission course finishes.

Judge if desired whether j class resource satisfies when being received condition, and the event horizon of j class resource will be set to t _{J (max)}, the space boundary will be set to d _{J (max)}Receive vehicle at t _iCorrespondence position when receiving " Resource Properties " packet constantly is (x _i, y _i).Calculate the t time of reception _iProduce t constantly to resource ₀Time interval t=t _i-t ₀With reception vehicle location (x _i, y _i) produce position (x to resource ₀, y ₀) between distance

Judge whether t, d satisfy t＜=t simultaneously _{J (max)}And d＜=d _{J (max)}Two conditions.If satisfy, then carry out step 5a); If do not satisfy, then rejection, transmission course finishes.

Step 5 is calculated correlation, receives resource successively.If have only a resource to wait to receive, then directly receive resource.If have a plurality of resources to need simultaneously to receive, then carry out step 5a) and 5b).

5a) calculate relevance function value F (R).According to following relevance function formula, the solving equation group obtains j class resource at position (x _i, y _i), moment t _iThe relevance function value.

$\left\{\begin{array}{cc}F\left(R\right)={\mathrm{\α}}_j\·t+{\mathrm{\β}}_j\·d+{\mathrm{\γ}}_j& ({\mathrm{\α}}_j\≤0,{\mathrm{\β}}_j\≤0)\\ d={[{(x_i-x_0)}^2+{(y_i-y_0)}^2]}^{\frac{1}{2}}& \\ t=t_i-t_0& \end{array}\right.$

Wherein: t is the moment t that vehicle receives packet _iProduce t constantly to resource ₀The time interval;

Position (x when d is vehicle reception packet _i, y _i) produce ground (x to resource ₀, y ₀) distance;

α _j, β _j, γ _jBe constant.α _j, β _jRepresent time interval t respectively and apart from the decay factor of d, γ _jBe the priority regulatory factor.α _j, β _j, γ _jThe size of numerical value is called according to the kind j of resource.

α _j, β _jSetting.

Because the correlation of resource reduces along with the increase of distance d, reduce along with the increase of time interval t, so α _j≤ 0, β _j≤ 0.α _j/ β _jValue more big, the expression correlation is for more strong than the space of the sensitiveness of time; On the contrary, then the sensitiveness to the space is stronger.Since some resource only with space correlation or time correlation, as with " position of certain building " of space correlation, perhaps with " stock information in some time " of time correlation.With space correlation, set α for only _j=0, only with time correlation, set β _j=0.

γ _jSetting.

For different resources, on the one hand, because the difference of factors such as user's demand, urgency level, transmission sequence is just different in its transmission course, so need to set priority, makes its urgency level height, important information priority transmission; On the other hand, along with the increase of propagation distance d and the growth of duration t, resource can reduce for user's urgency level or influence degree, and its priority can reduce, and therefore needs to set the priority of a dynamic change.

Below in conjunction with 2 pairs of priority regulatory factors of accompanying drawing γ _jSetting be further described:

Fig. 2 (a), expression resource R ₁" traffic accident, traffic jam take place " during the somewhere, its parameter is α ₁, β ₁, t _{1 (max)}, d _{1 (max)}Fig. 2 (b), expression resource R ₂" vehicle is the state information in somewhere (speed, position, acceleration, brake ...) at a time ", its parameter is α ₂, β ₂, t _{2 (max)}, d _{2 (max)}Fig. 2 (c), expression resource R ₃" positional information of gas station ", its parameter are α ₃=0, β ₃, d _{3 (max)}This three category information, resource R ₁Urgency level is the highest, resource R ₂Take second place resource R ₃Minimum.Though resource R ₁Urgency level is the highest, and still along with the increase of distance, its importance for the user will descend.That is to say just do not have resource R for the significance level than this information of vehicle at a distance ₂The degree height, the user more wishes to receive earlier resource R ₂Therefore, be set in d ₁(d ₁＜d _{1 (max)}) in the scope, resource R ₁Have limit priority.

Resource R ₁: at d ₁In the scope,

Resource R ₂: F (R ₂) _{Max (d=0, t=0)}=γ ₂

$F{\left(R_2\right)}_{\min (d=d_{2\left(\max \right)},t=t_{2\left(\max \right)})}={\mathrm{\α}}_2\·t_{2\left(\max \right)}+{\mathrm{\β}}_2\·d_{2\left(\max \right)}+{\mathrm{\γ}}_2$

Resource R ₃: F (R ₃) _{Max (d=0)}=γ ₃

By following inequality group, determine γ ₁, γ ₂, γ ₃Span.

$\left\{\begin{array}{c}F{\left(R_1\right)}_{\min (d=d_1,t=t_{1\left(\max \right)})}\≥F{\left(R_2\right)}_{\max (d=0,t=0)}\\ F{\left(R_2\right)}_{\min (d=d_{2\left(\max \right)},t=t_{2\left(\max \right)})}\≥F{\left(R_3\right)}_{\max (d=0)}\end{array}\right.$

Abbreviation obtains

$\left\{\begin{array}{c}{\mathrm{\γ}}_1\≥{\mathrm{\γ}}_2-{\mathrm{\α}}_1\·t_{1\left(\max \right)}-{\mathrm{\β}}_1\·d_1\\ {\mathrm{\γ}}_2\≥{\mathrm{\γ}}_3-{\mathrm{\α}}_2\·t_{2\left(\max \right)}-{\mathrm{\β}}_2\·d_{2\left(\max \right)}\end{array}\right.$

So, γ ₁, γ ₂, γ ₃As long as satisfying above-mentioned relation, the selection of numerical value can achieve the goal.

5b) queuing.Rank according to the order that the relevance function value is descending, receive resource successively.

Claims (4)

1. One kind in vehicle communication based on the resource regulating method of time and spatial coherence, comprise the steps:

   (1) sends vehicle foundation and resource " Resource Properties " packet one to one;

   (2) " Resource Properties " packet is sent to the reception vehicle by wireless channel;

   Whether (3) receive the vehicle inspection packet and exist in memory headroom, if exist, then reject resource, transmission course finishes; If do not exist, then carry out step (4);

   (4) by " Resource Properties " packet, judge that whether resource satisfies the condition that is received, if satisfy, then carries out step (5); If do not satisfy, then rejection, transmission course finishes;

   (5) receive resource: if having only a resource to wait to receive, then directly receive resource; If have a plurality of resources to need simultaneously to receive, then carry out step 5a) and 5b);

   5a) calculate relevance function value F (R)

   $\left\{\begin{array}{cc}F\left(R\right)={\mathrm{\α}}_j\·t+{\mathrm{\β}}_j\·d+{\mathrm{\γ}}_j& ({\mathrm{\α}}_j\≤0,{\mathrm{\β}}_j\≤0)\\ d={[{(x_i-x_0)}^2+{(y_i-y_0)}^2]}^{\frac{1}{2}}& \\ t=t_i-t_0& \end{array}\right.$

   Wherein: t is the moment t that vehicle receives packet _iProduce t constantly to resource ₀The time interval;

   Position (x when d is vehicle reception packet _i, y _i) produce ground (x to resource ₀, y ₀) distance;

   α _j, β _j, γ _jBe constant, α _j, β _jRepresent time interval t respectively and apart from the decay factor of d, γ _jBe the priority regulatory factor, j is the classification of resource;

   5b) queuing: rank according to the order that the relevance function value is descending, receive resource successively.
2. According to claim 1 in vehicle communication based on the resource regulating method of time and spatial coherence, it is characterized in that: the Resource Properties in the described step (1) refer to the initial generation of resource place, time, classification, produce the user of this resource.
3. According to claim 1 in vehicle communication based on the resource regulating method of time and spatial coherence, it is characterized in that: the resource condition of acceptance in the described step (4) refers to that t, d must satisfy t≤t simultaneously _J(max)And d≤d _{J (max)}Two conditions; T and d are respectively by formula t=t _i-t ₀, $d={[{(x_i-x_0)}^2+{(y_i-y_0)}^2]}^{\frac{1}{2}}$ Try to achieve, t is the moment t that vehicle receives packet _iProduce t constantly to resource ₀The time interval; Position (x when d is vehicle reception packet _i, y _i) produce ground (x to resource ₀, y ₀) distance; t _{J (max)}Be the event horizon of j class resource, d _{J (max)}Be the space boundary of j class resource, t _{J (max)}, d _{J (max)}Be according to setting resource coverage, effective time.
4. According to claim 1 in vehicle communication based on the resource regulating method of time and spatial coherence, it is characterized in that: attenuation factor in the described step (5) _j, β _jWith priority regulatory factor γ _jSize call according to the kind j of resource.