CN102917054B - A kind of In-vehicle networking Streaming Media forecasting method and device - Google Patents

Abstract

The invention discloses a kind of In-vehicle networking Streaming Media forecasting method, relate to the field of video applications of mobile Internet. Described method comprises: the neighbours' vehicle in its wireless signal coverage of vehicle detection, calculates the relative stability of described neighbours' vehicle and described vehicle; Described vehicle is to the high neighbours' vehicle request of the relative stability video content of looking ahead; Described neighbours' vehicle described video content of looking ahead, and send to described vehicle. The present invention can improve the efficiency of sharing streaming media resource between vehicle, has very high feasibility.

Description

A kind of In-vehicle networking Streaming Media forecasting method and device

Technical field

The present invention relates to the field of video applications of mobile Internet, particularly a kind of In-vehicle networking Streaming Media forecasting methodAnd device.

Background technology

Along with the development of wireless vehicle mounted network technology, some new application are disposed in In-vehicle networking. 802.11pCan provide playing stream media video needed high bandwidth, thereby realize the Stream Media Application under In-vehicle networking. Moving vehicleBetween conventionally rely on the adhoc(point-to-point) mode carries out vehicle-to-vehicle(V2V) and communication, thereby the resource of realizationInformation sharing and cooperating with each other, is conducive to the deployment of large-scale vehicle-mounted stream media system. But wireless channel is intrinsicThe fast moving of stability and vehicle all can be brought tremendous influence to level and smooth broadcasting of Streaming Media. Secondly, this for videoThe download of jumbo file, the mode (communicating by letter between vehicle and AP) that only depends on V2I is removed to obtain video content and can be broughtLonger download time, thus reduce video resource share efficiency.

At present, cooperation has become the fundamental guiding ideology of optimization system performance in various fields, as the car based on cooperationLoading system, based on cooperation vehicle encounters early warning system, the data transfer optimization based on P2P etc. But, in existing research,Mostly adopt the mode downloading video files based on AP cooperation, vehicle is first from the AP of current access_iObtain initial stream matchmakerVolume data, then pass through AP_iSearch the AP that may access in a certain period in future when vehicle in front_j, and ask AP_jAssistance vehicle is downloadedRequired video content. When vehicle is through AP_jTime, AP_jThe video content that can look ahead is transferred to vehicle, accelerates to download thereby realizeObject.

For example, existing being correlated with assisted being suggested of the common scheme of downloading based on AP recently. This technology allows vehicle to useWWAN radio (as GPRS) notifies selected AP to assist to look ahead. The stream medium data of looking ahead copies to this locality or other moveOn mobile carrier, in the time that request is assisted vehicle this AP of process looking ahead or met with mobile vehicle, it is pre-that this vehicle can obtain cooperationThe stream medium data of getting. Vehicle, by looking ahead of assisting based on AP, has been broken through the restriction of bandwidth, and can download within a short period of timeLarge-scale video file. MobTorrent technology has improved handling capacity and the resource-sharing situation of VANETs, but depends on oneThe prerequisite of individual necessity: the flowing information of vehicle must use automatic station-keeping system (AVL) and mobile historical record of past to enterThe travel route in row high-precision forecast vehicle future.

Another solution of assisting based on AP has proposed an AP deployment strategy based on density, by utilizing in cityCooperation under city's environment between vehicle downloads to optimize the performance that multi-hop transmits. This solution must be obtained enough Vehicle Driving CyclesThereby the possibility of historical record prediction vehicle encounters, and then realize the cooperation transmission between vehicle. But multi-hop transmission can be subject to conventionallyWait interference to longer time delay and the frequent disconnection of communication connection, thereby reduced efficiency of transmission.

Another kind of solution has proposed one and has utilized the mode of associated diagram to select the carrier that cooperates. By between vehicleThereby historical driving trace set up the associated diagram between vehicle. AP can estimate by associated diagram the car of foradownloaded video contentWith the probability that meets with between the vehicle of downloading that cooperates, be that it assists to download required stream matchmaker thereby select suitable cooperation vehicleVolume data. But, estimate that to information exchange between vehicle the possibility that two cars meets can not be very to AP and AP by APGood guarantee cooperation carrier can be given the content delivery of looking ahead request vehicle at short notice, and larger information exchange is openedPin and longer startup time delay all do not meet the real-time requirement of streaming media service.

Realizing in process of the present invention, inventor finds that prior art at least exists following problem:

Solution of the prior art, assisting to download based on AP needs continuous interaction message between AP, and for carRunning route also need to obtain in advance, the efficiency of sharing streaming media resource between vehicle is not high, thereby has reduced this solution partyThe feasibility of case.

Summary of the invention

In order to solve the problem of prior art, the embodiment of the present invention provide a kind of In-vehicle networking Streaming Media forecasting method andDevice. Described technical scheme is as follows:

A kind of In-vehicle networking Streaming Media forecasting method, described method comprises:

Neighbours' vehicle in its wireless signal coverage of vehicle detection, calculates the phase of described neighbours' vehicle and described vehicleTo stability;

Described vehicle is to the high neighbours' vehicle request of the relative stability video content of looking ahead;

Described neighbours' vehicle described video content of looking ahead, and send to described vehicle.

The relative stability of the described neighbours' vehicle of described calculating and described vehicle, comprising:

Set up neighbours' vehicle list neiL of described vehicle_i=(v₁,v₂,...,v_n), and setting cycle T carries out neighbor listRenewal;

For be still positioned at described neighbours' vehicle list neiL after upgrading_i＝(v₁,v₂,...,v_n) in neighbours' carCarry out relative stability assessment;

According to described neighbours' vehicle at described neighbours' vehicle list neiL_i＝(v₁,v₂,...,v_n) the middle time existingDetermine the relative stability of described neighbours' vehicle.

Described method also comprises:

Set up described vehicle V_iStable neighbor vehicle S set, described in

S=(newneiL_i∩neiL_i)=(v_a,v_b,...,v_k); Wherein, described newneiL_i=(v₁,v₂,...,v_m) for moreNeighbours' vehicle list after new;

Neighbours' vehicle intensity of variation G (V_i)=E(S^(c))-I(S^(p))G(V_i) wherein E (S of ∈ [1,1]^(c)) and I (S^(p)) be moreThe information content of neighbours' vehicle intensity of variation in S before and after new;

Described G (V_i) larger, described vehicle V_iThe stability of neighbours' vehicle is higher.

Described cycle T is set according to following mode:

According to the intensity of variation G (V of described neighbours' vehicle_i) adjustment cycle T, if G is (V_i) value lower, adjust described T moreLittle; Otherwise, if G is (V_i) value higher, adjust described T larger.

The setting of described cycle T is also set according to the intensity of variation of the high neighbours' vehicle of described relative stability.

Described method also comprises:

Assess the stability of described neighbours' vehicle with weighted factor; Described weighted factorWherein,WithWith respect to described vehicle V before and after described neighbours' vehicle list update_iThe normalized value of relative velocity;WithWith respect to described vehicle V before and after described neighbours' vehicle list update_iThe normalized value of displacement;

Described vr_ijValue lower, described neighbours' vehicle v_jStability larger.

Described vehicle, to the high neighbours' vehicle request of the relative stability video content of looking ahead, comprising:

Described vehicle V_iSend probe message to described neighbours' vehicle;

Described neighbours' vehicle adds its memory space and bandwidth information to be back to V to_iMessage in;

Described V_iFrom return messages, extract memory space and the bandwidth information of neighbours' vehicle;

As described V_iNeed its neighbours' vehicle to cooperate while looking ahead, selection relative stability is high and can have enoughMemory space and neighbours' vehicle of remaining bandwidth, as cooperation neighbours vehicle, ask needed video content.

A kind of In-vehicle networking Streaming Media prefetching device, described device comprises probe unit, stability computing unit, request listUnit and the transmitting element of looking ahead, wherein,

Described probe unit, for surveying the neighbours' vehicle in the wireless signal coverage of described vehicle;

Described stability computing unit, for calculating the relative stability of described neighbours' vehicle and described vehicle;

Described request unit, for the video content of looking ahead to the high neighbours' vehicle request of relative stability;

The described transmitting element of looking ahead, for the described video content of looking ahead, and sends to described vehicle.

Described stability computing unit further comprises neighbours' vehicle list subelement, intensity of variation computation subunit, weekPhase is set subelement and assessment subelement, wherein,

Described neighbours' vehicle list subelement, for storing the information of neighbours' vehicle and dynamically updating;

Described intensity of variation computation subunit, for calculating the intensity of variation of neighbours' vehicle list neighbours vehicle;

The described cycle is set subelement, for calculating and adjust the list of described neighbours' vehicle list subelement neighbours vehicleThe cycle that dynamically updates;

Described assessment subelement, for assessment of the stability of neighbours' vehicle.

Described request unit further comprises surveys subelement, storing sub-units and request subelement, wherein,

Described detection subelement, for sending probe message to described neighbours' vehicle;

Described storing sub-units, for by described neighbours' vehicle storage space and bandwidth information storage;

Described request subelement, for according to described neighbours' vehicle storage space and bandwidth information, and neighbours' vehicleStability is to described neighbours' vehicle request video content of looking ahead.

The beneficial effect that the technical scheme that the embodiment of the present invention provides is brought is:

By obtaining the stability of the neighbours' vehicle in automobile wireless signal cover, to the high neighbours' vehicle of stabilitySend request, require look ahead video content return to vehicle and play of neighbours' vehicle. Flat according to travelling of each vehicleAll the variation of speed and distance is as the stability weight of each neighbours' vehicle, thereby regulates accurately respective neighbours vehicleStability, realizes the stability of assessing more accurately vehicle. The embodiment of the present invention does not need to obtain the running route of vehicle, based onBetween the vehicle of V2V, cooperate, carry out common foradownloaded video content by the bandwidth from other vehicles to other vehicles and the memory space that utilize,Downloading process that not only can the large file of accelerating video, and can improve the efficiency of sharing streaming media resource between vehicle, haveVery high feasibility.

Brief description of the drawings

In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, required making in describing embodiment belowWith accompanying drawing be briefly described, apparently, the accompanying drawing in the following describes is only some embodiments of the present invention, forThose of ordinary skill in the art, are not paying under the prerequisite of creative work, can also obtain other according to these accompanying drawingsAccompanying drawing.

Fig. 1 is the In-vehicle networking Streaming Media forecasting method flow chart that the embodiment of the present invention provides;

Fig. 2 is the relative stability schematic diagram that the embodiment of the present invention one provides;

Fig. 3 is the In-vehicle networking Streaming Media prefetching device structural representation that the embodiment of the present invention two provides;

Fig. 4 is stability computing unit 200 structural representations that the embodiment of the present invention two provides;

Fig. 5 is request unit 300 structural representations that the embodiment of the present invention two provides.

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing to the invention process sideFormula is described in further detail.

In prior art, all ignore based on V2V for the shared solution of streaming media resource content in In-vehicle networkingVehicle between cooperate, ask to set up cooperation relation between the vehicle of streaming medium content and its down hop vehicle. When request vehicleRequiring its stable down hop vehicle is its certain video content of looking ahead, and not only can guarantee to cooperate can have between both sidesStreaming medium content is shared on effect ground, and has reduced the dependence of looking ahead by AP.

The embodiment of the present invention has proposed the Streaming Media prefetch policy based on stable cooperation neighbours perception under a kind of In-vehicle networking,Be called for short SND. The all vehicles in its 802.11p signal cover are all considered as (the letter of down hop neighbours vehicle by each vehicleClaim neighbours' vehicle), and wireless signal overlay area is defined as to its direct neighbor region (INR). By perception neighbour intelligentlyOccupy the variation (leaving or stay INR) of vehicle running state thus the stability of assessing each neighbours' vehicle (rests on INR'sTime), the most stable neighbours' vehicle can be selected cooperation neighbours and remove the required media content of looking ahead that cooperates, request streaming media resourceVehicle can to require neighbours' vehicle that stability is the highest be its certain video content of looking ahead, and be transmitted to after download completesRequest vehicle, shares thereby realize efficient streaming media resource.

Embodiment mono-

As shown in Figure 1, the In-vehicle networking Streaming Media forecasting method flow chart providing for the embodiment of the present invention, wherein,

Step 10, the neighbours' vehicle in its wireless signal coverage of vehicle detection, calculating neighbours' vehicle and this vehicleRelative stability.

In the urban area of a non-linear route, vehicle is all equipped with gps receiver and a radio network interface. ThisInventive embodiments is by utilizing gps receiver to realize " location aware ", each car V_iCan obtain direct neighbor region (INR)In the geographical position of each neighbours' vehicle. Onboard wireless network interface support unit V_iAnd the biography of several data between its neighbours' vehicleDefeated and information mutual, realizes V2V communication. Not only can realize the transmission of streaming media video data, can also make V_iObtainThe status information including average speed of neighbours' vehicle.

V_iStore the relevant information of it and neighbours' vehicle: neiL with a list_i＝(v₁,v₂,...,v_n), this is V_iThe list of neighbours' vehicle, wherein,2 yuan of arrays, (X_c,Y_c) and sp_cRespectively vehicle V_cThingReason address and average speed. Along with the movement of vehicle, the position of neighbours' vehicle is also in dynamic variation, therefore list neiL_iAlsoIt is dynamic change.

By reusing the method for " location aware ", V_iJust can obtain new neighbours' vehicle list a: newneiL_i＝(v₁,v₂,...,v_m). By the comparison to new and old list, V_iJust can obtain each neighbours' vehicle situation of change (add,Leave or stop). If neighbours' vehicle v_jLeave or join V_iINR in, v so_jInformation just from neiL_i＝(v₁,v₂,...,v_n) middle deletion or increase. If neiL is after upgrading, v_jStill therein, V so_iJust to its stabilityAssess.

The stability assessment of neighbours' vehicle depends on their time of staying in INR. The time of staying is longer, and it is steady soQualitative just higher. Concrete process is as follows:

If S=is (newneiL_i∩neiL_i)=(v_a,v_b,...,v_k) be V_iThe set of stable neighbor vehicle because each in SNode is all through once or repeatedly upgrading afterwards still at V_iThe list of neighbours' vehicle in, wherein S length is k.

A time interval T of SND definition carrys out more new neighbor vehicle stock table. In order to accomplish and the news commentary neighbours' vehicleEstimate, will be set to the variable update cycle update time.

Stability assessment model based on weight is used for assessing the stability of neighbours' vehicle. By V_iWith the neighbours' vehicle in SRelative velocity and relative displacement carry out computational stability as weight.

Specifically, along with the movement of vehicle, the geographical position relation between neighbours' vehicle also can dynamic change, thereby makesneiL_iIn element also change (being leaving or entering of node). V_iCan reuse by T " location aware ", obtain newImmediate neighbor collection newneiL_i. Relatively newneiL_iWith neiL_i，V_iNot only can specify stable neighbours' vehicle and their groundThe variation of reason position, state (average speed and distance) intensity of variation that can also discovering neighbor vehicle. According to information theory model,We use comentropy G (V_i) represent neighbours' vehicle intensity of variation, as shown in Equation (1).

G(V_i)=E(S^(c))-I(S^(p))G(V_i) ∈ [1,1] formula (1)

Wherein E (S^(c)) and I (S^(p)) be the information content of upgrading neighbours' vehicle intensity of variation in the S of front and back, respectively by formula (2)Draw with follow-up formula (12).

$E\left(S^{\left(c\right)}\right)=\left\{\begin{array}{cc}{-P}^{\left(c\right)}{\log }_2{P}^{\left(c\right)}& 0<P^{\left(c\right)}<1\\ 0& P^{\left(c\right)}=0\\ 1& P^{\left(c\right)}=1\end{array}\right.$ Formula (2)

Wherein P^(c)For upgrading rear S^(c)The information content that the mobile status (average speed and distance) of middle all elements produces. LogicalCross analysis S^(c)The status information of middle all elements distributes, and we use least square method and linear regression analysis to calculate P^(c)。Make D (S^(c)) be S^(c)The status information set of middle all elements, wherein each element is made up of 2 tuples, uses respectivelyStore S^(c)In each element with respect to V_iRelative velocity and relative displacement, by formula (3) gained.

$D\left(S^{\left(c\right)}\right)=\{(v_a^{{\mathrm{sd}}_{\mathrm{ia}}},v_a^{\left|{\mathrm{sp}}_{\mathrm{ia}}\right|}),(v_b^{{\mathrm{sd}}_{\mathrm{ib}}},v_b^{\left|{\mathrm{sp}}_{\mathrm{ib}}\right|}),...,(v_k^{{\mathrm{sd}}_{\mathrm{ik}}},v_k^{\left|{\mathrm{sp}}_{\mathrm{ik}}\right|})\}$ Formula (3)

WhereinWithFor each element in S is to V_iDisplacement and average relative.Initial value can be by formula(4) gained.

$v_j^{{\mathrm{sd}}_{\mathrm{ij}}}=\sqrt{{(X_i-X_j)}^2+{(Y_i-Y_j)}^2}0\&le;v_j^{{\mathrm{sd}}_{\mathrm{ij}}}\&le;v_{\mathrm{MAX}}^{\mathrm{sd}}$ Formula (4)

Wherein (Xi, Yi) and (Xj, Yj) is respectively the physical address of Vi and vj,Be and V_iThe maximum value of distance, can be byValue be set to the radius R of INR.Initial value depend on the absolute value of the difference of average speed, by formula (5) gained.

$v_j^{\left|{\mathrm{sp}}_{\mathrm{ij}}\right|}=\left\{\begin{array}{cc}|V_i^{\mathrm{sp}}-v_j^{\mathrm{sp}}|& 0\&le;|V_i^{\mathrm{sp}}-v_j^{\mathrm{sp}}|<v_{\mathrm{MAX}}^{\mathrm{sp}}\\ v_{\mathrm{MAX}}^{\mathrm{sp}}& |V_i^{\mathrm{sp}}-v_j^{\mathrm{sp}}|\&GreaterEqual;v_{\mathrm{MAX}}^{\mathrm{sp}}\end{array}\right.$ Formula (5)

WhereinWithBe respectively V_iAnd v_jAverage speed,It is the maximum of relative velocity in SND. In order to facilitateSee, by D (S^(c)) in each element be normalized, shown in formula (6).

${\hat{v}}_j^{\left|{\mathrm{sp}}_{\mathrm{ij}}\right|}=\frac{v_j^{\left|{\mathrm{sp}}_{\mathrm{ij}}\right|}}{v_{\mathrm{MAX}}^{\mathrm{sp}}},$ ${\hat{v}}_j^{{\mathrm{sd}}_{\mathrm{ij}}}=\frac{v_J^{{\mathrm{sd}}_{\mathrm{ij}}}}{v_{\mathrm{MAX}}^{\mathrm{sd}}}$ ${\hat{v}}_j^{\left|{\mathrm{sp}}_{\mathrm{ij}}\right|},{\hat{v}}_j^{{\mathrm{sd}}_{\mathrm{ij}}}\&Element;\left[\mathrm{0,1}\right]$ Formula (6)

If V_iFor the initial point of this coordinate system, as shown in Figure 2, x axle and y axle represent respectively relative distance and relative velocity. D (S^(c)) in element just can be mapped in this coordinate system. L is D (S^(c)) linear regression straight line,The distance of initial point to lFrom. Carry out linear regression processing by least square method, we can obtain its coefficient correlationAnd vertical rangeComeAssessment Pi, shown in formula (7).

$P^{\left(c\right)}=r^{D\left(S^{\left(c\right)}\right)}\&times;(1-d_{V_i\&RightArrow;l}^{D\left(S^{\left(c\right)}\right)}),P^{\left(c\right)}\&Element;\left[\mathrm{0,1}\right]$ Formula (7)

WhereinBe the coefficient correlation of linear regression fit, it has shown S^(c)The different conditions level of middle all elements,Calculate gained by formula (8).Value larger, the state difference of middle element is just less.

$r^{D\left(S^{\left(c\right)}\right)}=\frac{\underset{c=1}{\overset{k}{\mathrm{\&Sigma;}}}|{\hat{v}}_c^{\left|{\mathrm{sp}}_{\mathrm{ic}}\right|}-\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sp}}}||{\hat{v}}_c^{{\mathrm{sd}}_{\mathrm{ic}}}-\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sd}}}|}{\sqrt{\underset{c=1}{\overset{k}{\mathrm{\&Sigma;}}}{|{\hat{v}}_c^{\left|{\mathrm{sp}}_{\mathrm{ic}}\right|}-\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sp}}}|}^2}\&times;\sqrt{\underset{c=1}{\overset{k}{\mathrm{\&Sigma;}}}{|{\hat{v}}_c^{{\mathrm{sd}}_{\mathrm{ic}}}-\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sd}}}|}^2}},r^{D\left(S^{\left(c\right)}\right)}\&Element;\left[\mathrm{0,1}\right]$ Formula (8)

WhereinWithBe respectively with respect to average speed and displacement, its value by formula (9) calculate gained.

$\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sp}}}=\frac{\underset{c=1}{\overset{k}{\mathrm{\&Sigma;}}}{\hat{v}}_c^{\left|{\mathrm{sp}}_{\mathrm{ic}}\right|}}{k},$ $\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sd}}}=\frac{\underset{c=1}{\overset{k}{\mathrm{\&Sigma;}}}{\hat{v}}_c^{{\mathrm{sd}}_{\mathrm{ic}}}}{k}\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sp}}},\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sd}}}\&Element;\left[\mathrm{0,1}\right]$ Formula (9)

Show S^(c)The mobile status of middle all elements and V_iThe deviation of mobile status, calculated by formula (10)Gained.Value lower, S is described^(c)Possibility in the INR that middle all elements rests on is higher.

$d_{V_i\&RightArrow;l}^{D\left(S^{\left(c\right)}\right)}=\frac{|b_l\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sp}}}-\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sd}}}|}{\sqrt{1+b_l^2}},d_{V_i\&RightArrow;l}^{D\left(S^{\left(c\right)}\right)}\&Element;\left[\mathrm{0,1}\right]$ Formula (10)

Wherein b_lD (S^(c)) slope of linear fit straight line, calculate gained by formula (11).

$b_l=\frac{\underset{c=1}{\overset{k}{\mathrm{\&Sigma;}}}{\hat{v}}_c^{\left|{\mathrm{sp}}_{\mathrm{ic}}\right|}{\hat{v}}_c^{{\mathrm{sd}}_{\mathrm{ic}}}-k\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sp}}}\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sd}}}}{\underset{c=1}{\overset{k}{\mathrm{\&Sigma;}}}{\left({\hat{v}}_c^{{\mathrm{sd}}_{\mathrm{ic}}}\right)}^2-k{\left(\stackrel{\&OverBar;}{{\hat{v}}^{\mathrm{sd}}}\right)}^2},b_l\&Element;[-\&infin;,+\&infin;]$ Formula (11)

Formula (12) has been described V_iNeighbours' vehicle list S before upgrading^(c)The mobile status of middle all elements (average speed andDistance) produce information content.

$I\left(S^{\left(p\right)}\right)=\left\{\begin{array}{cc}{-P}^{\left(p\right)}{\log }_2{P}^{\left(p\right)}& 0<P^{\left(p\right)}<1\\ 0& P^{\left(p\right)}=0\\ 1& P^{\left(p\right)}=1\end{array}\right.$ Formula (12)

$P^{\left(p\right)}=r^{D\left(S^{\left(p\right)}\right)}\&times;(1-d_{V_i\&RightArrow;l}^{D\left(S^{\left(p\right)}\right)}),P^{\left(p\right)}\&Element;\left[\mathrm{0,1}\right]$ Formula (13)

P^(p)Computational methods and P^(c)Identical. G (V_i) value larger, change just less, i.e. V_iNeighbours' vehicle just relatively steadyFixed.

The cycle T especially, is here according to the intensity of variation G (V of neighbours' vehicle_i) adjustment cycle, if G is (V_i) value lower,Adjust T less; Otherwise, if G is (V_i) value higher, adjust T larger. The setting of cycle T is also according to described relative stabilityThe intensity of variation of high neighbours' vehicle is set. Specific as follows:

Update strategy main thought based on timer is to make each mobile terminal within the T unit interval, upgrade it1-hop neighbours, can be divided into two kinds according to update cycle kind: the update cycle of Static and dynamic. For the static update cycle,Mobile terminal sends detection information to its 1-hop neighbours after each update cycle. The setting of update cycle has determined dimensionProtect 1-hop neighbours' cost and effect. For example, the update cycle is longer, can reduce the quantity of probe message, but cannot obtain 1-Hop neighbours' real-time status. On the contrary, the update cycle is shorter, can obtain in time 1-hop neighbours' real-time status, but it needsOften send detect-message, thereby increase the quantity of probe message. The present embodiment proposes the self-regulation of a update cycle and upgradesMechanism (SPUM). V_iMake the update cycle of dynamics change assess the state variation degree of the neighbours' vehicle in INR. SPUM canThereby to adjust the update cycle according to the state variation degree self adaptation of neighbours' vehicle. SPUM not only can bring cheaply moreNewly (probe message quantity is few), but also guarantee to find in time stable neighbours' vehicle. If there is a large amount of neighbours' cars before and after upgradingLeave or enter V_iINR, V_iThereby just reduce the status information that the update cycle obtains neighbours' vehicle in time and find stable neighbourOccupy vehicle, the status information of the neighbours' candidate that especially cooperates. Otherwise, V_iWill increase the update cycle reduces to be sent to neighboursThe probe message quantity of vehicle.

If ut_iFor the update cycle, and its initial value is set to be greater than 0s. Its update mechanism is true by following formula (14)Fixed:

ut_i＝ut′_i(1+R_i×sin(G(V_i))) formula (14)

Wherein ut_iAnd ut_i' be respectively V_iRenewal before and after update cycle, G (V_i) be the intensity of variation of current renewal, byFormula (1) gained. R_iTo affect G (V_i) weighted value, as shown in Equation (15).

$R_i=\frac{\left|S\right|}{\left|{\mathrm{newneiL}}_i\right|},R_i\&Element;\left[\mathrm{0,1}\right]$ Formula (15)

Wherein | S| and | newneiL_i| be respectively S set and newneiL_iElement number. R_iBe | S| and | newneiL_i|Quantity ratio, its value is larger, regulate ut '_iAbility just stronger.

Further, also need to have concrete model to set up for the stability assessment of neighbours' vehicle. FOR ALL WE KNOW,Neighbours' vehicle time of staying in INR is longer, and phase stability is just higher. Consider the impact that node mobility brings, we makeAssess its stability with the weighting time of staying (weighted factor). The intensity of variation of weighted factor (weight factor) is by formula (16)Shown in.

${\mathrm{vr}}_{\mathrm{ij}}=\sqrt{{({\hat{v}}_j^{\left|{\mathrm{sp}}_{\mathrm{ij}}\right|}-{\left({\hat{v}}_j^{\left|{\mathrm{sp}}_{\mathrm{ij}}\right|}\right)}^{\&prime;})}^2+{({\hat{v}}_j^{{\mathrm{sd}}_{\mathrm{ij}}}-{\left({\hat{v}}_j^{{\mathrm{sd}}_{\mathrm{ij}}}\right)}^{\&prime;})}^2}$ Formula (16)

WhereinWithTo upgrade INR front and back with respect to V_iThe normalized value of relative velocity.WithMoreNew INR front and back are with respect to V_iThe normalized value of displacement. Vr_ijValue lower, v_jMobile status change more stable.

V_iNeighbours' vehicle v_jStability can by formula (17) calculate gained.

${\mathrm{st}}_{\mathrm{ij}}=\left\{\begin{array}{cc}{\mathrm{st}}_{\mathrm{ij}}^{\&prime;}+{\mathrm{ut}}_i\&times;\cos \left({\mathrm{vr}}_{\mathrm{ij}}\right)& {\mathrm{PD}}_{\mathrm{INR}}>0\\ 0& {\mathrm{PD}}_{\mathrm{INR}}=0\end{array}\right.$ Formula (17)

Wherein st_iAnd st_i' be respectively V_iThe renewal of neighbours' vehicle before and after stability assessment value. PDINR is adjacentOccupy the quantity that vehicle experiences the update cycle in INR. If v_jBe the neighbours' vehicle that newly adds INR, its value is 0 so. Otherwise,V is described_jStable neighbours' vehicle, i.e. v_jRest on and in INR, exceed a update cycle. Therefore, by list neiL_iIn unitElement is expanded into 3 tuples by 2 tuples and stores its stability assessment value, and form is as follows: v_c<=>((X_c,Y_c),sp_c,st_c), whereinst_cIt is stability assessment value.

Step 20, vehicle is to the high neighbours' vehicle request of the relative stability video content of looking ahead.

First need to calculate according to the stability in above-mentioned steps, obtain the value of the stability of each neighbours' vehicle, thenChoose neighbours' vehicle that stability is higher in order to the request video content of looking ahead. As a rule, stability be chosen the highestNeighbours' vehicle carrys out request content.

As previously mentioned, V_iNeed to select the most stable neighbours' vehicle as cooperation neighbours. Although stability be one very heavyThe factor of wanting, but due to the requirement of the length of the video block of looking ahead, cooperation neighbours' local memory space and bandwidth all need to examineWorry is arrived, thereby meets V_iDemand. V_iSend probe message to its neighbours' vehicle, neighbours' vehicle is by its memory space and bandwidth letterCease to add to and be back to V_iMessage in. V_iFrom return messages, extract memory space and the bandwidth information of neighbours' vehicle. Work as V_iNeedWant its neighbours' vehicle to cooperate while looking ahead, V_iJust select neighbours' vehicle that stability assessment value is the highest and can have enoughMemory space and remaining bandwidth remove the cooperation V that looks ahead as its cooperation neighbours_iRequired video data. Prefetch request message format is fixedJustice is as follows: req=(vID, spt, len, source), and wherein vID represents the video ID of request, spt and len are respectively that request is pre-Get starting point and the length of video segment, source is the resource provisioning person of video content. In the time that cooperation neighbours obtain video block, associationDo neighbours and just notify V_i, and prepare to be transferred in due course V_i。

Step 30, neighbours' vehicle described video content of looking ahead, and send to this vehicle.

In fact, the present embodiment is to be based upon under the prerequisite that each vehicle forms In-vehicle networking jointly, when a vehicle needsWhen obtaining video content, need to complete with other neighbours' vehicle cooperative of periphery. Namely need to choose the cooperation of oneselfNeighbours, and connect with the neighbours that cooperate, the preparation of prefetching content completed. Be chosen as cooperation neighbours' vehicle and connect and work as a carWhen video content information is looked ahead in the request of receiving other vehicle, need to respond to this request, namely need basisThis request, in conjunction with self bandwidth and other situation, the video content information of looking ahead, and send to this request vehicle. So far, vehicle-mountedThe process that network flow-medium is looked ahead finishes.

In the embodiment of the present invention, request video resource vehicle taking its 802.11p signal cover time of staying asThe parameter of assessment neighbours intact stability, thereby neighborhood between the vehicle of the video resource of filing a request and its neighbours' vehicleStability assessment model, what make that selected cooperation neighbours can be stable provides the cooperation service of looking ahead for request vehicle. Select carThe distance of travelling between average speed and vehicle changes evaluate parameter as neighbours' intact stability of assessment request vehicle, therebyIn each update cycle, obtain the variable quantity of all neighbours' car speeds and distance, and then regulate the update cycle. Dynamic renewalCycle can reduce the more traffic volume of new information effectively, and can find timely neighbours' car of asking vehicle periphery stable.

Embodiment bis-

As shown in Figure 3, the embodiment of the present invention provides a kind of In-vehicle networking Streaming Media prefetching device, and this device comprises detectionUnit 100, stability computing unit 200, request unit 300 and the transmitting element 400 of looking ahead, specific as follows:

Probe unit 100, for the neighbours' vehicle in the wireless signal coverage of detection vehicle.

Stability computing unit 200, for calculating the relative stability of neighbours' vehicle and this vehicle.

Request unit 300, for the video content of looking ahead to the high neighbours' vehicle request of relative stability.

The transmitting element 400 of looking ahead, for the video content of looking ahead, and sends to this vehicle.

Especially, the transmitting element 400 of looking ahead is here actually at this device during as neighbours' vehicle, requested looking aheadWhen video content, carry out work according to request. In-vehicle networking Streaming Media prefetching device in the present embodiment, is arranged on tool conventionallyOn the vehicle of body, vehicle is all equipped with gps receiver and radio network interface. Realize " position sense by utilizing gps receiverKnow ", each car V_iCan obtain the geographical position of each neighbours' vehicle in INR. Onboard wireless network interface support unit V_iWith itBetween neighbours' vehicle, the transmission of several data and information is mutual, realizes V2V communication, not only can realize streaming media video dataTransmission, can also make V_iObtain the status information including average speed of neighbours' vehicle.

Further, as shown in Figure 4, stability computing unit 200 further comprise neighbours' vehicle list subelement 201,Intensity of variation computation subunit 202, cycle are set subelement 203 and assessment subelement 204, specific as follows:

Neighbours' vehicle list subelement 201, for storing the information of neighbours' vehicle and dynamically updating.

Intensity of variation computation subunit 202, for calculating the intensity of variation of neighbours' vehicle list neighbours vehicle.

Cycle is set subelement 203, for calculating and adjust neighbours' vehicle list subelement 201 neighbours' vehicle listsDynamically update the cycle.

Assessment subelement 204, for assessment of the stability of neighbours' vehicle.

Further, as shown in Figure 5, request unit 300 further comprises surveys subelement 301, storing sub-units 302 andRequest subelement 303, specific as follows:

Survey subelement 301, for sending probe message to neighbours' vehicle.

Storing sub-units 302, for by neighbours' vehicle storage space and bandwidth information storage.

Request subelement 303, for according to neighbours' vehicle storage space and bandwidth information, and the stability of neighbours' vehicleTo neighbours' vehicle request video content of looking ahead.

In sum, each embodiment of the present invention is by obtaining the steady of neighbours' vehicle in automobile wireless signal coverQualitative, the neighbours vehicle high to stability sends request, and requires look ahead video content return to vehicle and broadcast of neighbours' vehiclePut. Stability weight according to the variation of travel average speed and the distance of each vehicle as each neighbours' vehicle, fromAnd regulate accurately the stability of respective neighbours vehicle, realize the stability of assessing more accurately vehicle. The embodiment of the present invention is notNeed to obtain the running route of vehicle, between the vehicle based on V2V, cooperate, by utilize to other vehicles other vehicles bandwidth andMemory space carrys out common foradownloaded video content, downloading process that not only can the large file of accelerating video, and can improve vehicleBetween share the efficiency of streaming media resource, there is very high feasibility.

It should be noted that: the In-vehicle networking Streaming Media prefetching device that above-described embodiment provides is triggering In-vehicle networking stream matchmakerWhen body is looked ahead business, be only illustrated with the division of above-mentioned each functional module, in practical application, can be as required and incite somebody to actionAbove-mentioned functions distribution is completed by different functional modules, is divided into different functional modules, with complete by the internal structure of equipmentBecome all or part of function described above. In addition, above-described embodiment provides In-vehicle networking Streaming Media prefetching device and carCarry network flow-medium forecasting method embodiment and belong to same design, its specific implementation process refers to embodiment of the method, here no longerRepeat.

The invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.

One of ordinary skill in the art will appreciate that all or part of step that realizes above-described embodiment can pass through hardwareComplete, also can carry out the hardware that instruction is relevant by program and complete, described program can be stored in a kind of computer-readableIn storage medium, the above-mentioned storage medium of mentioning can be read-only storage, disk or CD etc.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all in spirit of the present invention andWithin principle, any amendment of doing, be equal to replacement, improvement etc., within protection scope of the present invention all should be included in.

Claims (9)

1. an In-vehicle networking Streaming Media forecasting method, is characterized in that, described method comprises:

Neighbours' vehicle in its wireless signal coverage of vehicle detection, calculates the relative steady of described neighbours' vehicle and described vehicleQualitative;

Described relative stability, calculates according to following mode:

Set up neighbours' vehicle list neiL of described vehicle_i＝(v₁,v₂,...,v_n), and setting cycle T carries out neighbor list moreNewly; Described v₁,v₂,...,v_nFor neighbours' vehicle of described vehicle;

For be still positioned at described neighbours' vehicle list neiL after upgrading_i＝(v₁,v₂,...,v_n) in neighbours' vehicle carry outRelative stability assessment;

According to described neighbours' vehicle at described neighbours' vehicle list neiL_i＝(v₁,v₂,...,v_n) in exist time determine instituteState the relative stability of neighbours' vehicle;

Described vehicle is to the high neighbours' vehicle request of the relative stability video content of looking ahead;

Described neighbours' vehicle described video content of looking ahead, and send to described vehicle.

2. the method for claim 1, is characterized in that, described method also comprises:

Set up described vehicle V_iStable neighbor vehicle S set, described S=(newneiL_i∩neiL_i)＝(v_a,v_b,...,v_k)；Wherein, described newneiL_i＝(v₁,v₂,...,v_m) be the neighbours' vehicle list after upgrading;

Neighbours' vehicle intensity of variation G (V_i)＝E(S^(c))-I(S^(p))G(V_i) ∈ [1,1], wherein E (S^(c)) and I (S^(p)) be to upgradeThe information content of neighbours' vehicle intensity of variation in the S of front and back;

Described G (V_i) larger, described vehicle V_iThe stability of neighbours' vehicle is higher.

3. method as claimed in claim 2, is characterized in that, described cycle T is set according to following mode:

According to the intensity of variation G (V of described neighbours' vehicle_i) adjustment cycle T, if G is (V_i) value lower, adjust described T less;Otherwise, if G is (V_i) value higher, adjust described T larger.

4. method as claimed in claim 3, is characterized in that, the setting of described cycle T is also high according to described relative stabilityThe intensity of variation of neighbours' vehicle set.

5. the method for claim 1, is characterized in that, described method also comprises:

Assess the stability of described neighbours' vehicle with weighted factor; Described weighted factor ${\mathrm{vr}}_{ij}=\sqrt{{({\hat{v}}_j^{\left|{\mathrm{sp}}_{ij}\right|}-{\left({\hat{v}}_j^{\left|{\mathrm{sp}}_{ij}\right|}\right)}^{\&prime;})}^2+{({\hat{v}}_j^{{\mathrm{sd}}_{ij}}-{\left({\hat{v}}_j^{{\mathrm{sd}}_{ij}}\right)}^{\&prime;})}^2};$ Wherein,WithThe normalization of described neighbours' vehicle list update front and back with respect to the relative velocity of described vehicle ViValue;WithThe normalized values of described neighbours' vehicle list update front and back with respect to the displacement of described vehicle Vi;

Described vr_ijValue lower, the stability of described neighbours' vehicle vj is larger.

6. the method for claim 1, is characterized in that, described vehicle is pre-to the high neighbours' vehicle request of relative stabilityGet video content, comprising:

Described vehicle Vi sends probe message to described neighbours' vehicle;

Described neighbours' vehicle adds its memory space and bandwidth information in the message that is back to Vi to;

Described Vi extracts memory space and the bandwidth information of neighbours' vehicle from return messages;

In the time that described Vi needs its neighbours' vehicle to cooperate to look ahead, select relative stability high and can have enough depositingNeighbours' vehicle of storage space and remaining bandwidth, as cooperation neighbours vehicle, asks needed video content.

7. an In-vehicle networking Streaming Media prefetching device, is characterized in that, described device comprises probe unit, stability calculating listUnit, request unit and the transmitting element of looking ahead, wherein,

Described probe unit, for the neighbours' vehicle in the wireless signal coverage of detection vehicle;

Described stability computing unit, for calculating the relative stability of described neighbours' vehicle and described vehicle;

Described relative stability, calculates according to following mode:

Set up neighbours' vehicle list neiL of described vehicle_i＝(v₁,v₂,...,v_n), and setting cycle T carries out neighbor list moreNewly; Described v₁,v₂,...,v_nFor neighbours' vehicle of described vehicle;

For be still positioned at described neighbours' vehicle list neiL after upgrading_i＝(v₁,v₂,...,v_n) in neighbours' vehicle carry outRelative stability assessment;

According to described neighbours' vehicle at described neighbours' vehicle list neiL_i＝(v₁,v₂,...,v_n) in exist time determine instituteState the relative stability of neighbours' vehicle;

Described request unit, for the video content of looking ahead to the high neighbours' vehicle request of relative stability;

The described transmitting element of looking ahead, for the described video content of looking ahead, and sends to described vehicle.

8. device as claimed in claim 7, is characterized in that, described stability computing unit further comprises neighbours' vehicle stockTable subelement, intensity of variation computation subunit, cycle are set subelement and assessment subelement, wherein,

Described neighbours' vehicle list subelement, for storing the information of neighbours' vehicle and dynamically updating;

Described intensity of variation computation subunit, for calculating the intensity of variation of neighbours' vehicle list neighbours vehicle;

The described cycle is set subelement, for calculating and adjust the moving of described neighbours' vehicle list subelement neighbours vehicle listThe state update cycle;

Described assessment subelement, for dynamically updating the stability of cycle evaluation neighbours vehicle described in basis.

9. device as claimed in claim 7, is characterized in that, described request unit further comprises surveys subelement, storageSubelement and request subelement, wherein,

Described detection subelement, for sending probe message to described neighbours' vehicle;

Described storing sub-units, for by described neighbours' vehicle storage space and bandwidth information storage;

Described request subelement, for according to described neighbours' vehicle storage space and bandwidth information, and neighbours' vehicle is stableProperty is to described neighbours' vehicle request video content of looking ahead.