CN104703142A - Game theory-based vehicular networking location tracking vehicle power control method - Google Patents

Abstract

The invention relates to a game theory-based vehicular networking location tracking vehicle power control method. According to the method, a vehicular networking vehicle power control problem is abstracted into a non-cooperative gam problem in the game theory, and an optimal solution under a Nash equilibrium condition is solved, namely the optimal transmitting power of each vehicle in the current state is solved. Besides, a periodic and trigger type combined HELLO broadcast strategy is adopted, the transmitting power of the vehicle is not required to be gradually increased for repeated detection, but the optimal transmitting power of each vehicle is directly calculated, and channel congestion caused by broadcast of a HELLO data packet is reduced. Since the optimal transmitting power of each vehicle is solved, the interference caused by the transmitting power is favorably reduced and the vehicle location tracking precision is provided. Thus, the method can be widely applied to the field of traffic safety.

Description

A kind of vehicle power control method based on game theoretic car networking location tracking

Technical field

The present invention relates to a kind of Poewr control method following the trail of vehicle, particularly about a kind of vehicle power control method based on game theoretic car networking location tracking.

Background technology

It is a crucial technology that power controls in car networking, at present in the power control of car networking, has proposed many strategies and mechanism.In car networking, transmitting power is too little directly causes the vehicle in certain limit cannot continue successful Received signal strength, is difficult to efficient communication, thus have impact on the connectedness of car networking; But transmitting power is excessive, inter-vehicular communication may be caused to disturb significantly to be increased, and packet loss increases.As can be seen here, transmitting power is excessive or too small, all by affecting car connected network communication effect, thus can reduce the precision of following the trail of neighbours' vehicle location, produces counter productive to car networking fail safe.Therefore, controlled by car networking power, ensure that between vehicle, location tracking precision is in higher interval, significant for car networking fail safe.

The transmitting power problem major embodiment of current car online vehicles is in the following areas:

1) adjust according to the local message of vehicle, do not consider the global information of network, the vehicle causing power larger likely can continue take and consume bandwidth, unfair for lower-powered vehicle, make lower-powered vehicle cannot complete the propagation of message of vehicular status, can not follow the trail of accurately vehicle.When carrying out power control, do not consider otherness individual between vehicle, in region, identical transmitting power taked by all vehicles often, and the optimal transmit power obtained under this assumption, owing to not considering the possibility that each vehicle emissions power is different, it not probably the transmitting power of system optimal.

2) some Poewr control method is when determining transmitting power owing to adopting the thinking of water flood, and transmitting power is soundd out from low to high repeatedly, therefore can produce a large amount of HELLO packet, occupy large volumes of channels resource.

Summary of the invention

For the problems referred to above, the object of this invention is to provide a kind of vehicle power control method based on game theoretic car networking location tracking improving vehicle location tracking precision in car networking.

For achieving the above object, the present invention takes following technical scheme: a kind of vehicle power control method based on game theoretic car networking location tracking, and it comprises the following steps: 1) each vehicle periodically sends the HELLO packet comprising this vehicle ID, motion state and messaging parameter; 2) each vehicle periodically receives the HELLO packet that other vehicles send over; 3) according to received HELLO packet, the neighbor node table of the vehicle self receiving HELLO packet is upgraded; 4) each vehicle adjusts the transmitting power of vehicle self according to the data in self neighbor node table; 5) each vehicle is according to the up-to-date motion state data of other vehicles in received HELLO packet, is predicted the position of other vehicles by vehicle location forecast model; 6) do you judge that the location tracking error of each vehicle in other vehicles in the neighbor node table of vehicle exceedes error threshold? if exceed, enter next step; Otherwise, return step 2) continue to receive the HELLO packet of other vehicles, to obtain the status data of neighbours' vehicle, dynamic conditioning is in time carried out for transmitting power, improve vehicle location and follow the trail of precision; 7) broadcast location tracking error exceedes the emergency message bag of the vehicle of threshold value, and this emergency message comprises the object vehicle ID sending the vehicle ID of this emergency message bag and location tracking error and exceed threshold value; 8) this emergency message bag of object vehicle receiver, all the other vehicles abandon this packet after receiving this emergency data bag automatically; 9) after this emergency message bag of object vehicle receiver, self interference volume is calculated, and directly send interference volume to the vehicle sending emergency message bag; 10) object vehicle broadcast HELLO packet gives the vehicle sending emergency message bag, and returns step 2) periodically receive HELLO packet, the constantly transmitting power of each vehicle of adjustment.

Described step 1) in the motion state of described vehicle comprise position, speed and acceleration; The messaging parameter of described vehicle comprises interference volume and link gain.

Described step 4) adopt $P_{\mathrm{Ti}}=-\underset{p=1}{\overset{N1}{\mathrm{\Σ}}}\frac{r_{\mathrm{Tp}}\left(t\right){\mathrm{\γ}}_p\left(t\right)d_{\mathrm{ij}}^k\left(t\right)P_{\mathrm{Tp}}}{{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)d_{\mathrm{pj}}^k\left(t\right)}-\underset{q=1}{\overset{N2}{\mathrm{\Σ}}}\frac{2^k{r}_{\mathrm{Tq}}\left(t\right){\mathrm{\γ}}_q\left(t\right)d_{\mathrm{ij}}^k\left(t\right)P_{\mathrm{Tq}}}{3^k{R}_{\mathrm{thre}}^k{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}+\frac{{\mathrm{\μ}}_i{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}{\ln 2}-\frac{d_{\mathrm{ij}}^k\left(t\right)\mathrm{\σ}{\left(t\right)}^2}{{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}$ Regulate transmitting power, wherein, P _tiit is the transmitting power of vehicle node i; r _tpt () is the transmission rate of any t vehicle node p, r _tqt () is the transmission rate of any t vehicle node q; P _tpfor the transmitting power of any t vehicle node p, P _tqfor the transmitting power of any t vehicle node q; γ _pt () is the obstacle gain of any t vehicle node p, γ _qt () is the obstacle gain of any t vehicle node q; μ _ifor the income gain of vehicle node i; σ (t) ²for interchannel noise; d _ijt () is the distance between vehicle node i during t and vehicle node j; for any t as the vehicle node i of interfering nodes for the link gain of the vehicle node j as receiving node, wherein, G _tfor transmitting terminal antenna gain, G _rfor receiving terminal antenna gain, h _tfor transmitting terminal antenna height, h _rfor receiving terminal antenna height, L is system loss, and d is the spacing of transmitting terminal to receiving terminal, k ∈ [2,4]; N ₁for the interference source number in communication range, N ₂for the interference source number outside communication range.

Described step 9) in interference volume be the product of this object vehicle node transmission rate, transmitting power and obstacle gain.

The present invention is owing to taking above technical scheme, it has the following advantages: 1, the present invention by abstract for car online vehicles Power Control Problem be non-cooperative game problem in a game theory, obtain the optimal solution under Nash Equilibrium condition, namely the transmitting power of each vehicle optimum under current state.Therefore, the present invention taken into account car networking power control in fairness and individual difference, obtain vehicle emissions power optimum under current state.2, present invention employs the HELLO broadcast strategy that periodic and trigger-type combine, and without the need to vehicle emissions power is soundd out repeatedly by low progressively heightening, and directly calculate the optimal transmit power of each vehicle, settle at one go, decrease the channel congestion because broadcast HELLO packet causes.The present invention, owing to having drawn each vehicle optimal transmit power, is conducive to reducing the interference that causes of transmitting power and provides vehicle location to follow the trail of precision, to ensure vehicle pass-through safety in car networking.In view of above reason, the present invention can be widely used in field of traffic safety.

Accompanying drawing explanation

Fig. 1 is communication scheme between car online vehicles

Fig. 2 is flow chart of the present invention

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail.

As shown in Figure 1, the present invention includes following steps:

1) as shown in Figure 2, each vehicle periodically sends the HELLO packet (hello packet) comprising this vehicle ID, motion state and messaging parameter, and this HELLO packet is the common practise of those skilled in the art.

Wherein, each vehicle in car networking has an ID (identity, authentication); The motion state of vehicle comprises position, speed and acceleration; The messaging parameter of vehicle comprises interference volume and link gain.

The 802.11p agreement that the clock cycle that each vehicle sends HELLO packet proposes according to IEEE, is set as 50ms.

2) each vehicle periodically receives the HELLO packet that other vehicles send over;

3) according to received HELLO packet, upgrade the neighbor node table of the vehicle self receiving HELLO packet, in neighbor node table, data are motion state and the messaging parameter of up-to-date neighbours' vehicle;

4) each vehicle adjusts according to the transmitting power of the data in up-to-date neighbor node table for vehicle self.

Because the transmitting power by improving self all attempted by each vehicle, to improve the signal to noise ratio of self communication, thus improve self communication experience.But, if in fact each vehicle is all simply by improving signal to noise ratio, attempt to improve self communication to experience, because of the raising of transmitting power, and system communication interference can be increased on the contrary, the signal to noise ratio of inter-vehicular communication may be reduced so on the one hand on the contrary, interference causes packet loss to increase on the other hand, and packet loss increase is unfavorable for that vehicle obtains the up-to-date HELLO packet of other vehicles, thus the tracking precision that dips, reduce car networking fail safe.Therefore, above-mentioned vehicle power control problem can abstractly be the non-cooperative game problem in a game theory, and this problem is under Nash Equilibrium condition, has optimal solution, the namely optimal transmit power of each vehicle under current system conditions.

Theoretical according to the non-cooperative game in game theory, if there is Nash Equilibrium point, then during Nash Equilibrium, entire system reaches balanced optimum.Now, need the existence and the uniqueness that prove Nash Equilibrium point, when carrying out Nash Equilibrium point subsequently, solving of each vehicle emissions power.

Define any t vehicle node i as follows to the revenue function of vehicle node j transmission HELLO packet:

u _i(t)＝μ _ilog ₂(1+SNR _ij(t))-c(P _Ti(t))

Wherein, μ _ilog ₂(1+SNR _ij(t)) be Gaussian channel capacity formula, μ _ifor income gain, for the cost function of vehicle node i, due to transmitting power interval [0, the P of each vehicle node _max], therefore policy space be a non-NULL, close, the convex set of bounded.Again because revenue function u _it () is continuous, therefore have

$\frac{{\∂u}_i(P_{\mathrm{Ti}},P_{T-i})}{\∂P_{\mathrm{Ti}}}=\frac{{\mathrm{\μ}}_i{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}{\ln 2[d_{\mathrm{ij}}^k\left(t\right)(\mathrm{\σ}{\left(t\right)}^2+I_j\left(t\right))+P_{\mathrm{Ti}}{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)]}-\frac{1}{{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}$

Wherein, vectorial P _t-ifor the transmitting power of the game participant vehicle node beyond vehicle node i.I _jt () is the interference value at any t vehicle node j place.Order then be updated in above formula by the modeling result of interference, when obtaining Nash Equilibrium, optimal transmit power formula is as follows:

$P_{\mathrm{Ti}}=-\underset{p=1}{\overset{N1}{\mathrm{\Σ}}}\frac{r_{\mathrm{Tp}}\left(t\right){\mathrm{\γ}}_p\left(t\right)d_{\mathrm{ij}}^k\left(t\right)P_{\mathrm{Tp}}}{{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)d_{\mathrm{pj}}^k\left(t\right)}-\underset{q=1}{\overset{N2}{\mathrm{\Σ}}}\frac{2^k{r}_{\mathrm{Tq}}\left(t\right){\mathrm{\γ}}_q\left(t\right)d_{\mathrm{ij}}^k\left(t\right)P_{\mathrm{Tq}}}{3^k{R}_{\mathrm{thre}}^k{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}+\frac{{\mathrm{\μ}}_i{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}{\ln 2}-\frac{d_{\mathrm{ij}}^k\left(t\right)\mathrm{\σ}{\left(t\right)}^2}{{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}$

Wherein, P _tiit is the transmitting power of vehicle node i; r _tpt () is the transmission rate of any t vehicle node p, r _tqt () is the transmission rate of any t vehicle node q; P _tpfor the transmitting power of any t vehicle node p, P _tqfor the transmitting power of any t vehicle node q; γ _pt () is the obstacle gain of any t vehicle node p, γ _qt () is the obstacle gain of any t vehicle node q; μ _ifor the income gain of vehicle node i; σ (t) ²for interchannel noise; d _ijt () is the distance between vehicle node i during any t and vehicle node j. for any t as the vehicle node i of interfering nodes for the link gain of the vehicle node j as receiving node, wherein, G _tfor transmitting terminal antenna gain, G _rfor receiving terminal antenna gain, h _tfor transmitting terminal antenna height, h _rfor receiving terminal antenna height, L is system loss, and d is the spacing of transmitting terminal to receiving terminal, general k ∈ [2,4].N ₁for the interference source number in communication range, N ₂for the interference source number outside communication range.

In sum, the transmitting power of vehicle node i is determined jointly by income gain, link gain, obstacle gain, communication separation between vehicles, interchannel noise and reception vehicle interference value.

5) each vehicle is according to the up-to-date motion state data of other vehicles in received HELLO packet, is predicted the position of other vehicles by vehicle location forecast model.

Particularly, by discretization continuous time, be divided into the timeslice of several equal lengths.By the motion state comprising position, speed and acceleration that predicted vehicle sends over, by physical motion principle, predict the vehicle location after several timeslices.Because existing vehicle location forecast model is prior art, do not do to limit to adopt which kind of vehicle location forecast model at this.

6) do you judge that the location tracking error of each vehicle in other vehicles in the neighbor node table of vehicle exceedes error threshold? if exceed, enter next step; Otherwise, return step 2) continue to receive the HELLO packet of other vehicles, to obtain the status data of neighbours' vehicle, dynamic conditioning is in time carried out for transmitting power, improve vehicle location and follow the trail of precision.

Location tracking error threshold is 1.07 meters, because 1.07 meters is 95% truncated errors of location tracking error, namely have the possibility of 95%, location tracking error amount is no more than 1.07 meters.

7) broadcast location tracking error exceedes the emergency message bag of threshold value vehicle, and this emergency message comprises the object vehicle ID sending the vehicle ID of this emergency message bag and location tracking error and exceed threshold value;

8) this emergency message bag of object vehicle receiver, all the other vehicles abandon this packet after receiving this emergency data bag automatically;

9) after this emergency message bag of object vehicle receiver, self interference volume is carried out calculating preliminary treatment, and directly send interference volume to the vehicle sending emergency message bag, reduce the traffic on the one hand, reduce the amount of calculation of the transmission vehicle node receiving HELLO packet on the other hand.

Wherein, interference volume is the product of this object vehicle node transmission rate, transmitting power and obstacle gain.

10) object vehicle sends HELLO packet to the vehicle sending emergency message bag, automatically this packet is abandoned after other all the other vehicle receiver HELLO packet, the vehicle receiver sending emergency message bag is only had to go forward side by side row relax, thus step 7) ~ step 10) complete trigger-type transmission HELLO packet, then each vehicle returns to normal, and returns step 2) periodically receive HELLO packet.

Vehicle receiver HELLO data in above-mentioned each car networking are surrounded by two class sources: a class is when location tracking error exceeds threshold value, according to step 7) ~ step 10), tracked location tracking error sends to follower's vehicle with exceeding the vehicle trigger-type of threshold value, comprises the HELLO packet of oneself latest state information.Another kind of be each vehicle periodically according to clock cycle broadcast HELLO packet, obtain its status data to facilitate surrounding vehicles.

In sum, the present invention car is networked Power Control Problem abstract be the non-cooperative game problem in game theory, under Nash Equilibrium condition, this problem can obtain optimal solution, namely corresponds to the optimal transmit power of each vehicle under current vehicle online vehicles state.Transmission power adjustment is periodically and triggeringly combines, and is obtained the required data of calculating transmitting power by HELLO packet.Trigger condition is that vehicle location tracking error exceedes threshold value.

The various embodiments described above are only for illustration of the present invention; wherein the structure of each parts, connected mode and manufacture craft etc. all can change to some extent; every equivalents of carrying out on the basis of technical solution of the present invention and improvement, all should not get rid of outside protection scope of the present invention.

Claims (4)

1., based on a vehicle power control method for game theoretic car networking location tracking, it comprises the following steps:

1) each vehicle periodically sends the HELLO packet comprising this vehicle ID, motion state and messaging parameter;

2) each vehicle periodically receives the HELLO packet that other vehicles send over;

3) according to received HELLO packet, the neighbor node table of the vehicle self receiving HELLO packet is upgraded;

4) each vehicle adjusts the transmitting power of vehicle self according to the data in self neighbor node table;

5) each vehicle is according to the up-to-date motion state data of other vehicles in received HELLO packet, is predicted the position of other vehicles by vehicle location forecast model;

6) do you judge that the location tracking error of each vehicle in other vehicles in the neighbor node table of vehicle exceedes error threshold? if exceed, enter next step; Otherwise, return step 2) continue to receive the HELLO packet of other vehicles, to obtain the status data of neighbours' vehicle, dynamic conditioning is in time carried out for transmitting power, improve vehicle location and follow the trail of precision;

7) broadcast location tracking error exceedes the emergency message bag of the vehicle of threshold value, and this emergency message comprises the object vehicle ID sending the vehicle ID of this emergency message bag and location tracking error and exceed threshold value;

8) this emergency message bag of object vehicle receiver, all the other vehicles abandon this packet after receiving this emergency data bag automatically;

9) after this emergency message bag of object vehicle receiver, self interference volume is calculated, and directly send interference volume to the vehicle sending emergency message bag;

10) object vehicle broadcast HELLO packet gives the vehicle sending emergency message bag, and returns step 2) periodically receive HELLO packet, the constantly transmitting power of each vehicle of adjustment.

2. a kind of vehicle power control method based on game theoretic car networking location tracking as claimed in claim 1, is characterized in that: described step 1) in the motion state of described vehicle comprise position, speed and acceleration; The messaging parameter of described vehicle comprises interference volume and link gain.

3. a kind of vehicle power control method based on game theoretic car networking location tracking as claimed in claim 1 or 2, is characterized in that: described step 4) adopt $P_{\mathrm{Ti}}=-\underset{p=1}{\overset{N1}{\mathrm{\Σ}}}\frac{r_{\mathrm{Tp}}\left(t\right){\mathrm{\γ}}_p\left(t\right)d_{\mathrm{ij}}^k\left(t\right)P_{\mathrm{Tp}}}{{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)d_{\mathrm{pj}}^k\left(t\right)}-\underset{q=1}{\overset{N2}{\mathrm{\Σ}}}\frac{2^k{r}_{\mathrm{Tp}}\left(t\right){\mathrm{\γ}}_q\left(t\right)d_{\mathrm{ij}}^k\left(t\right)P_{\mathrm{Tq}}}{3^k{R}_{\mathrm{thre}}^k{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}+\frac{{\mathrm{\μ}}_i{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}{\ln 2}-\frac{d_{\mathrm{ij}}^k\left(t\right)\mathrm{\σ}{\left(t\right)}^2}{{\mathrm{\δ}}_{\mathrm{ij}}\left(t\right)}$ Regulate transmitting power, wherein, P _tiit is the transmitting power of vehicle node i; r _tpt () is the transmission rate of any t vehicle node p, r _tqt () is the transmission rate of any t vehicle node q; P _tpfor the transmitting power of any t vehicle node p, P _tqfor the transmitting power of any t vehicle node q; γ _pt () is the obstacle gain of any t vehicle node p, γ _qt () is the obstacle gain of any t vehicle node q; μ _ifor the income gain of vehicle node i; σ (t) ²for interchannel noise; d _ijt () is the distance between vehicle node i during t and vehicle node j; for any t as the vehicle node i of interfering nodes for the link gain of the vehicle node j as receiving node, wherein, G _tfor transmitting terminal antenna gain, G _rfor receiving terminal antenna gain, h _tfor transmitting terminal antenna height, h _rfor receiving terminal antenna height, L is system loss, and d is the spacing of transmitting terminal to receiving terminal, k ∈ [2,4]; N ₁for the interference source number in communication range, N ₂for the interference source number outside communication range.

4. a kind of vehicle power control method based on game theoretic car networking location tracking as claimed in claim 3, is characterized in that: described step 9) in interference volume be the product of this object vehicle node transmission rate, transmitting power and obstacle gain.