Patent ID: 12254768

EXAMPLE EMBODIMENT

<Problems of Present Disclosure>

Prior to the description of example embodiments according to the present disclosure, problems of the present disclosure are described in detail with reference toFIGS.1to3.

Here, the two cases described below are assumed, as illustrated inFIG.1.

(A1) Case where a mobile object, such as a vehicle, transmits a packet at predetermined transmission intervals, while moving in movement direction (1)

(A2) Case where the mobile object transmits a packet at predetermined transmission intervals, while moving in movement direction (2) that is opposite to movement direction (1)

The mobile object causes a packet to include at least positional information indicating a position of the mobile object, and a packet number. The packet transmitted by the mobile object passes through a base station20, and is received by a remote monitoring apparatus. The remote monitoring apparatus calculates delay jitter by using, for example, Formula 1 described below.
Delay jitter=reception time ofi-th packet−reception time of(I−1)th packet  [Formula 1]

FIG.2illustrates an example of delay jitter in case (A1) described above, andFIG.3illustrates an example of delay jitter in case (A2) described above. InFIGS.2and3, a horizontal axis indicates a packet number, and a vertical axis indicates delay jitter of a packet having the packet number. In case (A1) described above, an initial value of the packet number is 0, and the packet number increases in every movement. In contrast, in case (A2) described above, an initial value of the packet number is 250, and the packet number decreases in every movement. Therefore, the packet numbers on the horizontal axes inFIGS.2and3indicate the same position of the mobile object.

As illustrated inFIGS.2and3, it is apparent that delay jitter varies depending on a position of the mobile object.

Furthermore, in a comparison betweenFIGS.2and3, it is apparent that even if the mobile object is located in the same position, delay jitter varies depending on a movement direction of the mobile object.

Therefore, in the remote monitoring apparatus, in order to specify a delay jitter distribution with high accuracy, it is necessary to learn a delay jitter distribution model that corresponds to geographical characteristics such as a position or a movement direction of the mobile object, and know that a certain type of delay jitter distribution is obtained in a certain section of a movement section where the mobile object moves.

However, if the movement section of the mobile object is divided into sections having a fixed size, the problem described below arises depending on size. For example, the case of a large fixed size causes a problem in which plural types of delay jitter distributions appear in the same section. Furthermore, the case of a small fixed size causes a problem in which the same type of delay jitter distribution is separated over a plurality of sections.

As described above, if the movement section of the mobile object is divided into sections having a fixed size, the problems described above result in a deterioration of the accuracy of specification of a delay jitter distribution. Therefore, the movement section of the mobile object needs to be appropriately divided.

Furthermore, the present disclosure has another problem.

It is known that the delay jitter distribution conforms to a Laplace distribution.

However, in a delay jitter distribution based on the Laplace distribution, a variation in delay jitter due to a variation in communication quality, such as the simultaneous arrival of packets or packet loss, is not considered.

Therefore, in order to specify a delay jitter distribution with high accuracy, a delay jitter distribution model in consideration of the simultaneous arrival of packets or packet loss also needs to be learned.

Respective example embodiments of the present disclosure that are described below contribute to solution to the problems described above.

Example embodiments of the present disclosure are described below with reference to the drawings. Note that in the description and drawings described below, omission and simplification are made as appropriate, for clarity of description. Furthermore, in each of the drawings described below, the same elements are denoted by the same reference signs, and a duplicate description is omitted as necessary. Moreover, in each of the example embodiments described below, description is provided under the assumption that a mobile object serving as a target to be monitored is a vehicle such as an automobile, but the mobile object is not limited to the vehicle.

First Example Embodiment

First, an example of the entire configuration of a remote monitoring system1according to the present first example embodiment is described with reference toFIG.4.

As illustrated inFIG.4, the remote monitoring system1according to the present first example embodiment includes a vehicle10and a remote monitoring apparatus50.

The vehicle10is connected to a base station20through a wireless network. The wireless network is a network such as 3rd generation (3G), 4G/long term evolution (LTE), 5G, local 5G, or wireless fidelity (Wi-Fi).

The vehicle10is further connected through the base station20and the Internet30to the remote monitoring apparatus50that is disposed on a cloud40. However, this is not restrictive, and an aspect may be employed where the vehicle is directly connected to a network on a side of the remote monitoring apparatus50through the wireless network without using the Internet30.

Next, examples of configurations of the vehicle10and the remote monitoring apparatus50according to the present first example embodiment are described with reference toFIG.5.

As illustrated inFIG.5, the vehicle10according to the present first example embodiment includes a vehicle information specification unit11and a vehicle information transmission unit12.

The vehicle information specification unit11specifies a state of the vehicle10.

The vehicle information transmission unit12transmits, to the remote monitoring apparatus50, a packet including at least vehicle information indicating the state of the vehicle10that has been specified by the vehicle information specification unit11, and a packet number.

Note that in the present first example embodiment, it is assumed that the vehicle information specification unit11specifies at least a position of the vehicle10, and the vehicle information includes at least a time stamp, and information relating to a position of the vehicle10at the time indicated by the time stamp. However, this is not restrictive, and the vehicle information may also include information indicating a state or the like of the speed of the vehicle10, a steering wheel, or a residual amount of fuel.

The remote monitoring apparatus50according to the present first example embodiment includes a vehicle information reception unit51, a delay jitter specification unit52, and a section division unit53.

The vehicle information reception unit51receives the packet including the vehicle information from the vehicle10.

The delay jitter specification unit52calculates, for each position of the vehicle10, delay jitter in a network that performs communication with the vehicle on the basis of the packet received from the vehicle10, and the vehicle information included in the packet. In the example ofFIG.4, the network that performs communication with the vehicle10is a network that includes the wireless network between the vehicle10and the base station20, the Internet30, and the network on a side of the remote monitoring apparatus50. The delay jitter specification unit52can calculate delay jitter by using, for example, Formula 1 described above.

The section division unit53learns a delay jitter distribution model in a movement section where the vehicle10moves, on the basis of the delay jitter for each of the positions of the vehicle10that has been calculated by the delay jitter specification unit52. Moreover, the section division unit53divides the movement section of the vehicle10on the basis of the delay jitter for each of the positions of the vehicle10and the learned delay jitter distribution model, and specifies a delay jitter distribution in each of the divided sections. Note that the movement section of the vehicle10and the network that performs communication with the vehicle10correspond to each other.

Note that the remote monitoring apparatus50may be provided with a monitoring unit (not illustrated) that monitors a running situation of the vehicle10. The monitoring unit may calculate the time to collision (TTC), which is a remaining time period before collision of the vehicle10, on the basis of the vehicle information received from the vehicle10, and may calculate a degree of risk of the vehicle10on the basis of the TTC. Furthermore, the monitoring unit may modify the TTC on the basis of delay jitter in a section where the vehicle10is moving, and may calculate the degree of risk on the basis of the modified TTC. For example, it is conceivable that the TTC is modified to be shorter in a section having large delay jitter.

Furthermore, the monitoring unit may control the vehicle10on the basis of a result of monitoring the vehicle10. For example, in a case where the vehicle10has a high degree of risk, the monitoring unit may perform control, for example, to apply the sudden brakes or reduce traveling speed. Furthermore, if the vehicle10is an automated driving vehicle, the monitoring unit may perform switching from automated driving to remote driving.

An operation of the section division unit53according to the present first example embodiment is described in detail below.

(B1) Delay Jitter Distribution Model

First, a delay jitter distribution model to be used by the section division unit53is described with reference toFIGS.6and7.

As illustrated inFIG.6, the vehicle10transmits a packet at predetermined transmission intervals.

Therefore, in a case where communication quality is normal, the remote monitoring apparatus50receives the packet from the vehicle10at intervals that correspond to the predetermined transmission intervals.

However, in a case where the simultaneous arrival of packets or packet loss occurs, in the remote monitoring apparatus50, an interval of reception of a packet from the vehicle10varies, and this results in a variation in delay jitter.

Furthermore, it is known that a delay jitter distribution conforms to a Laplace distribution, as illustrated inFIG.7. InFIG.7, a horizontal axis indicates delay jitter, and a vertical axis indicates a probability of the delay jitter.

In a case where communication quality is normal, the remote monitoring apparatus50receives a packet from the vehicle10at intervals that correspond to the predetermined transmission intervals. Therefore, in a delay jitter distribution, a peak is generated in a position that corresponds to a transmission interval of a packet.

However, in a case where the simultaneous arrival of packets or packet loss occurs, in the remote monitoring apparatus50, an interval of reception of a packet from the vehicle10varies, and this results in a variation in delay jitter. Therefore, in the delay jitter distribution, a plurality of peaks is generated. Furthermore, in a case where communication quality drastically varies, the skirt of the delay jitter distribution is widened.

In view of this, the section division unit53according to the present first example embodiment employs a delay jitter distribution model based on a mixed Laplace distribution in which a plurality of Laplace distributions has been mixed, and specifies a delay jitter distribution in the movement section of the vehicle10, by using this delay jitter distribution model based on the mixed Laplace distribution.

A delay jitter distribution model fθ(y) according to the present first example embodiment is defined by using Formula 2 described below, for example, in the case of a mixed Laplace distribution in which g Laplace distributions have been mixed.

fθ(y)=∑j=1gξj⁢fj(y;ϕj)[Formula⁢2]

In this formula, θ is a model parameter, y is observation data indicating delay jitter for each position of the vehicle10, fj(y; φj) is a j-th Laplace distribution, and ξjis a mixing ratio indicating a ratio observed from the j-th Laplace distribution.

Furthermore, the j-th Laplace distribution fj(y; φj) is defined by using Formula 3 described below.

fj(y;ϕj)=ℒ⁡(y|(μj,βj))=12⁢βj⁢exp⁡(-❘"\[LeftBracketingBar]"y-μj❘"\[RightBracketingBar]"βj)[Formula⁢3]

In this formula, βjis a population parameter of a scale, and μjis a population parameter of a position.

Furthermore, various parameters in Formulae 2 and 3 described above are defined by using Formula 4 described below.
Λ={ξ1, . . . ,ξg−1}T
θ={Λ,ϕ1, . . . ,ϕg}T
ϕj={μj,βj}
ξg=1−ξ1− . . . −ξg−1[Formula 4]
(B2) Section Division

Next, an operation for the section division unit53to divide the movement section of the vehicle10is described with reference toFIG.8.

The section division unit53has a basic policy that the movement section of the vehicle10is divided in such a way that the delay jitter distribution specified by using the delay jitter distribution model based on the mixed Laplace distribution that has been described above can most appropriately express an actual delay jitter distribution.

Step S1:

The section division unit53obtains, from the delay jitter specification unit52, observation data yifor the entire movement section in a movement direction of the vehicle10, which is defined by Formula 5 described below.
yi={y1, . . . ,yn}T[Formula 5]

Then, the section division unit53learns a model parameter θiof the delay jitter distribution model, by using the observation data yi.

Then, the section division unit53specifies a delay jitter distribution for the entire movement section of the vehicle10, by using the delay jitter distribution model, the learned model parameter θi, and the observation data yi, and calculates the log-likelihood of the specified delay jitter distribution, which is defined by Formula 6 described below.
l(θi,yi)=logf(yi|θi)  [Formula 6]
Step S2:

Next, the section division unit53calculates a mean and a variance of the observation data yiby using a movement window having a predetermined length, and divides the movement section of the vehicle10into N sections by using the k-means method or the like.

Then, the section division unit53specifies a delay jitter distribution for each of the divided sections by using the observation data in a corresponding section, similarly to step S1, and calculates the log-likelihood of the specified delay jitter distribution, which is defined by Formula 7 described below.
l(θiN,yiN)=logf(yiN|θiN)  [Formula 7]
Step S3:

Next, the section division unit53determines whether the total of log-likelihoods of respective sections after division that have been calculated in step S2has been improved in comparison with the log-likelihood before division that has been calculated in step S1. In a case where the total has been improved, step S1and step S2are repeated, and further section division is performed.

Stated another way, the section division unit53repeats step S1and step S2while Formula 8 described below is satisfied.

l⁡(θi,yi)<∑k=1Nl⁡(θik,yi⁢k)[Formula⁢8]

The section division unit53terminates section division at a point in time when Formula 8 described above is not satisfied. Then, the section division unit53specifies respective sections before most recent section division as respective final sections. As described above, the section division unit53divides the movement section of the vehicle10in such a way that the total of log-likelihoods for respective sections after division increases.

Here, an example of a method for learning the model parameter θiof the delay jitter distribution model in step S1described above is described.

The model parameter θican be calculated by using, for example, the expectation maximization (EM) algorithm for the mixed Laplace distribution.

The EM algorithm for the mixed Laplace distribution can be calculated as described below.

E-step:
Q(θ,θ(k))  [Formula 9]
is calculated.

For this calculation, Formulae 10 and 11 described below are used.

zij(k)=ξj(k)⁢fj(yi|ϕj(k))∑j=1g⁢ξj(k)⁢fj(yi|ϕj(k))[Formula⁢10]Q⁡(θ,θ(k))=Eθ(k)[l⁡(θ,X)|Y=y]=∑i=1n∑j=1gzi⁢j(k)⁢log⁢fj(yi|ϕj)+∑i=1n∑j=1gzi⁢j(k)⁢log⁢ξj[Formula⁢11]

M-step:

∂∂θQ⁡(θ,θ(k))=0[Formula⁢12]
is calculated, and
θ(k+1),  [Formula 14]
which is a parameter that maximizes
Q(θ,θ(k)),  [Formula 13]
is calculated.

For this calculation, Formulae 15 to 17 described below are used.

ξj(k+1)=1n⁢∑i=1nzi⁢j(k);j=1,…,g-1[Formula⁢15]μj(k+1)=median⁢(y;j=argmaxjzj(k))[Formula⁢16]βj(k+1)=average⁢(❘"\[LeftBracketingBar]"yi-μj(k+1)❘"\[RightBracketingBar]";j=argmaxjzij(k))[Formula⁢17]

Then, E-step and M-step described above are repeated until the likelihood becomes less than a threshold.
l(θ(k+1),y)−l(θ(k),y)>ϵmin[Formula 18]

Next, an initial value of the EM algorithm is described.
zij(o)[Formula 19]
can be calculated by using Formulae 20 and 21 described below.
zi1(o)=1foryi<τmin[Formula 20])
zij(o)=1(j>1) for τ*j−δ<yi<τ*(j+1)−δ  [Formula 21]

In these formulae, τ is a transmission interval, τminis a lower limit value of the transmission interval (a minimum value of the observed delay jitter is set), and δ is a constant (for example, a value of ½ the transmission interval).
μj(o)[Formula 22]
is the same as
μj(k+1)[Formula 23]
βj(o)[Formula 24]
is the same as
βj(k+1)[Formula 25]
ξj(o)[Formula 26]
is the same as
ξj(k+1)[Formula 27]
in a case where a loss rate is unknown in advance.

In a case where it is known in advance that the loss rate is p (for example, in a case where a loss rate of p can be calculated on the basis of a sequence number or the like), a probability that loss will not occur can be calculated by using Formula 28 described below.

pnon-loss=1-(ρ+ρ2+…+ρn)=ρ-ρn1-ρ→ρ1-ρ⁢(n→∞)[Formula⁢28]

Accordingly, an occurrence probability of a Laplace distribution at a time when j≥2 can be calculated by using Formula 29 described below with c as a standardization constant.

ξj={c⁢ρ1-ρ;j=2c⁢ρj-2;j>2[Formula⁢29]

A Laplace distribution at a time when j=1 (a delay jitter distribution at a time when the simultaneous arrival of packets has occurred) is generated when delay jitter is two times or more the transmission interval, and therefore the Laplace distribution is expressed by using Formula 30 described below.

ξ1=∑j=2g∫μj+τ∞fj(y;ϕj)⁢dy[Formula⁢30]

Furthermore, the standardization constant is expressed by using Formula 31 described below.

c=(1-ξ1)g-1[Formula⁢31]
(C1) Usefulness of Delay Jitter Distribution Model Based on Mixed Laplace Distribution

Next, a verification result of verifying the usefulness of a delay jitter distribution model based on the mixed Laplace distribution that has been described above in (B1) is described with reference toFIGS.9to13.

Here, as illustrated inFIG.9, the assumption is made that a mobile object10X for which a position has been fixed transmits a 500-byte packet to the remote monitoring apparatus50through the base station20at transmission intervals of 10 ms. Here, the mobile object10X causes the packet to include at least a packet number.

FIG.10illustrates observation data serving as delay jitter that has been calculated by the delay jitter specification unit52of the remote monitoring apparatus50under the assumption illustrated inFIG.9. A horizontal axis and a vertical axis inFIG.10are similar to the horizontal axis and the vertical axis inFIGS.2and3. However, inFIG.9, the position of the mobile object10X has been fixed, and therefore positions of the mobile object10X are the same as each other, even if packet numbers are different from each other.

FIG.11illustrates a delay jitter distribution that has been calculated on the basis of the delay jitter illustrated inFIG.10.FIG.12illustrates a delay jitter distribution that has been specified by using a delay jitter distribution model based on the Laplace distribution.FIG.13illustrates a delay jitter distribution that has been specified by using the delay jitter distribution model based on the mixed Laplace distribution according to the present first example embodiment. A horizontal axis and a vertical axis inFIGS.11to13are similar to the horizontal axis and the vertical axis inFIG.7.

As illustrated inFIG.11, in an actually calculated delay jitter distribution, a plurality of peaks that has been caused by the simultaneous arrival of packets, or the like or the widening of a skirt that has been caused by a variation in communication quality is observed.

In contrast, as illustrated inFIG.12, the delay jitter distribution that has been specified by using the delay jitter distribution model based on the Laplace distribution is a distribution having a stretched skirt, and it is apparent that a plurality of peaks or the like that has been caused by the simultaneous arrival of packets, or the like fails to be expressed.

On the other hand, as illustrated inFIG.13, it is apparent that the delay jitter distribution that has been specified by using the delay jitter distribution model based on the mixed Laplace distribution according to the present first example embodiment can appropriately express a plurality of peaks that has been caused by the simultaneous arrival of packets, or the like or the widening of a skirt that has been caused by a variation in communication quality.

Therefore, it is apparent that the delay jitter distribution model based on the mixed Laplace distribution according to the present first example embodiment has been able to learn a delay jitter distribution in consideration of the simultaneous arrival of packets or packet loss, with high accuracy.

(C2) Usefulness of Section Division Based on Likelihood

Next, a verification result of verifying the usefulness of section division based on likelihood that has been described above in (B2) is described with reference toFIGS.14to20. Usefulness in this case is determined on the basis of whether the delay jitter distribution model based on the mixed Laplace distribution according to the present first example embodiment has been able to learn a delay jitter distribution for each of the divided sections, with high accuracy.

Here, as illustrated inFIG.14, the assumption is made that the mobile object10X is carried, for example, by a user, and transmits a 500-byte packet to the remote monitoring apparatus50through the base station20at transmission intervals of 10 ms, while moving in movement direction (1) (in a direction toward the base station20and in a direction away from the base station20). Here, the mobile object10X causes the packet to include, at least, positional information indicating a position of the mobile object10X, and a packet number.

FIG.15is a diagram illustrating a result of performing section division on a movement section of the mobile object10X on the basis of delay jitter under the assumption illustrated inFIG.14.

An upper diagram ofFIG.15illustrates observation data serving as delay jitter for each position of the mobile object10X that has been calculated by the delay jitter specification unit52of the remote monitoring apparatus50under the assumption illustrated inFIG.14. A horizontal axis and a vertical axis inFIG.15are similar to the horizontal axis and the vertical axis inFIGS.2and3. InFIG.14, the mobile object10X transmits the packet while moving. Therefore, in the upper diagram ofFIG.15, a packet number on the horizontal axis corresponds to a position of the mobile object10X.

A middle diagram and a lower diagram ofFIG.15illustrate that a mixed Laplace distribution of which cluster ID expresses a delay jitter distribution for which section in the movement section of the mobile object10X, the middle diagram ofFIG.15illustrates a state before section division, and the lower diagram ofFIG.15illustrates a state after section division. In the middle diagram and the lower diagram ofFIG.15, a horizontal axis indicates a packet number, and a vertical axis indicates a cluster ID of a mixed Laplace distribution expressing a delay jitter distribution for a section including a position where a packet having the packet number has been transmitted.

A log-likelihood before section division was −4.753×104, whereas a log-likelihood after section division has been improved to −4.431×104. In this case, a log-likelihood that is closer to 0 indicates further improvements.

As illustrated in the middle diagram ofFIG.15, before section division, a delay jitter distribution for the entirety of the movement section is expressed by a single mixed Laplace distribution of cluster ID 0.

In contrast, as illustrated in the lower diagram ofFIG.15, after section division, a delay jitter distribution for each of the divided sections is expressed by any of five mixed Laplace distributions of clusters ID 0 to ID 4. For example, a delay jitter distribution for a section including a position where a packet having packet number 0 has been transmitted is expressed by a mixed Laplace distribution of cluster ID 2. Furthermore, a delay jitter distribution for a section including a position where a packet having packet number 3500 has been transmitted is expressed by a mixed Laplace distribution of cluster ID 0.

FIGS.16to20respectively illustrate mixed Laplace distributions of clusters ID 0 to ID 4. A horizontal axis and a vertical axis inFIGS.16to20are similar to the horizontal axis and the vertical axis inFIG.7.

As illustrated inFIGS.16and17, mixed Laplace distributions of clusters ID 0 and ID 1 are distributions having a widened skirt.

As illustrated inFIG.18, a mixed Laplace distribution of cluster ID 2 is a distribution expressing a steep increase in delay jitter.

As illustrated inFIGS.19and20, mixed Laplace distributions of clusters ID 3 and ID 4 are distributions expressing a small variation in delay jitter.

Here, with reference to the upper diagram ofFIG.15, a variation in delay jitter is small, for example, near a section where packets having packet numbers 1000 to 2000 have been transmitted. A delay jitter distribution of a section near this section is expressed by a mixed Laplace distribution of any of clusters ID 3 and ID 4, which expresses a small variation in delay jitter.

Furthermore, a variation in delay jitter is great near a section where packets having packet numbers 3000 to 3500 have been transmitted. A delay jitter distribution of a section near this section is expressed by any of mixed Laplace distributions of clusters ID 0 and ID 1, which have a widened skirt, and a mixed Laplace distribution of cluster ID 2, which expresses a steep increase in delay jitter.

Therefore, it is apparent that the delay jitter distribution model based on the mixed Laplace distribution according to the present first example embodiment has been able to learn a delay jitter distribution that is adapted to geographical characteristics such as a position or a movement direction of a mobile object, and grasps features of each of the divided sections, with high accuracy.

Next, an example of a flow of an operation of the remote monitoring apparatus50according to the first example embodiment is described with reference toFIG.21.

As illustrated inFIG.21, first, the delay jitter specification unit52calculates delay jitter for each position of the vehicle10in the entire movement section of the vehicle10that corresponds to a network that performs communication with the vehicle10(step S11).

Next, the section division unit53learns a delay jitter distribution model for a current section (in step S12of the first time, the entire movement section of the vehicle10) on the basis of delay jitter in the current section that has been calculated in step S11. Moreover, the section division unit53specifies a delay jitter distribution for the current section on the basis of the delay jitter for the current section and the learned delay jitter distribution model, and calculates the likelihood of the specified delay jitter distribution (step S12).

Next, the section division unit53divides the current section. Then, the section division unit53specifies a delay jitter distribution for each of the divided sections on the basis of the delay jitter for a corresponding section and the learned delay jitter distribution model, and calculates the likelihood of the specified delay jitter distribution (step S13).

Next, the section division unit53determines whether the total of likelihoods for respective divided sections of the current section that have been calculated in step S13has been improved in comparison with the likelihood for the current section that has been calculated in step S12(step S14).

In a case where the likelihood has been improved in step S14(Yes in step S14), the processing returns to step S12, and the section division unit53performs the processes of steps S12and S13for each of the divided sections obtained in step S13, by using each of the divided sections as a current section.

In contrast, in a case where the likelihood has not been improved in step S14(No in step S14), the section division unit53terminates the processing. As a result, the section division unit53specifies respective sections before section division in step S13of the most recent time as respective final sections.

As described above, according to the present first example embodiment, the delay jitter specification unit52calculates delay jitter in a network that performs communication with the vehicle10. The section division unit53divides a movement section that corresponds to the network and where the vehicle moves, on the basis of the calculated delay jitter, and specifies a delay jitter distribution in each of the divided sections. As described above, the movement section of the vehicle10is divided, and a delay jitter distribution in each of the divided sections is specified. Therefore, a delay jitter distribution that corresponds to geographical characteristics such as a position or a movement direction of the vehicle10can be specified.

Furthermore, according to the present first example embodiment, the section division unit53specifies a delay jitter distribution by using a delay jitter distribution model based on a mixed Laplace distribution. This delay jitter distribution model can learn a delay jitter distribution in consideration of the simultaneous arrival of packets or packet loss, with high accuracy. Therefore, the delay jitter distribution in consideration of the simultaneous arrival of packets or packet loss can be specified.

Furthermore, according to the present first example embodiment, the section division unit53divides the movement section of the vehicle10in such a way that the likelihood of the mixed Laplace distribution increases. Therefore, the movement section of the vehicle10can be divided in such a way that a delay jitter distribution is adapted to geographical characteristics such as a position or a movement direction of the vehicle10, grasps features in each of the divided sections, and has high accuracy.

Second Example Embodiment

A remote monitoring system1A according to the present second example embodiment has a different configuration of the remote monitoring apparatus50in comparison with the first example embodiment described above.

Accordingly, an example of a configuration of the remote monitoring apparatus50according to the present second example embodiment is described below with reference toFIG.22.

As illustrated inFIG.22, the remote monitoring apparatus50according to the present second example embodiment is different in that a section display unit54is added, in comparison with the configuration ofFIG.5according to the first example embodiment described above.

The section display unit54displays divided sections obtained by the section division unit53on a map indicating a movement section of the vehicle10.

An example of a display of each of the divided sections that has been conducted by the section display unit54is illustrated inFIG.23. In the example ofFIG.23, the section display unit54classifies respective sections on the road by using patterns, and adds delay jitter in each of the sections.

However, the example of the display illustrated inFIG.23is not restrictive. For example, the section display unit54may classify the respective sections on the road by using color. Furthermore, the section display unit54may display a mark indicating a warning in a section having large delay jitter. The section display unit54may also classify the respective sections by using gradual color-coding, depending on delay jitter or a delay jitter distribution. The section display unit54may also display a list of names or coordinates of the respective sections. Furthermore, if any of the sections has been designated by clicking or the like, the section display unit54may display detailed information relating to the designated section.

Furthermore, in the examples of the display ofFIGS.23to25, the section display unit54displays each of the divided sections on a screen of the remote monitoring apparatus50, but this is not restrictive. The section display unit54may display each of the divided sections in an arbitrary display device other than the remote monitoring apparatus50(for example, a display device of a monitoring center that monitors the road).

Furthermore, the monitoring unit described above (not illustrated) may simultaneously monitor a plurality of vehicles10. As an example of a display of each of the divided sections that is conducted by the section display unit54, an example of a display in a case where a plurality of vehicles10is simultaneously monitored is illustrated inFIG.24. In the example of the display ofFIG.24, the section display unit54displays a plurality of vehicles10. Then, if any of the vehicles10has been designated by clicking or the like, the section display unit54displays detailed information relating to the designated vehicle10.FIG.24illustrates an example where the detailed information of the vehicle10is displayed in a balloon to be superimposed onto a monitoring screen, but a display method is not limited to this.

As another example of a display of each of the divided sections that is conducted by the section display unit54, an example of a display in a case where a degree of risk of the vehicle10is monitored is illustrated inFIG.25. In the example of the display ofFIG.25, the section display unit54displays a screen for monitoring in an upper left-hand side portion ofFIG.25, but detailed information relating to the vehicle10may be displayed in a superimposed manner. Furthermore, the section display unit54may display a video of a monitoring camera that takes a picture of the vehicle10or a video of a monitoring camera in the vicinity, as illustrated in a lower left-hand side portion ofFIG.25. The section display unit54may also display a list of vehicles10having a high degree of risk, as illustrated in an upper right-hand side portion ofFIG.25. Furthermore, the section display unit54may conduct an enlarged display of a vehicle10that has been designated by clicking or the like, as illustrated in a lower right-hand side portion ofFIG.25, or may display a screen for remote driving in a case where the vehicle10is switched from automated driving to remote driving.

Note that the operation described above of the monitoring unit may be performed by any of the vehicle information reception unit51, the delay jitter specification unit52, the section division unit53, and the section display unit54. In this case, the monitoring unit may be omitted.

Next, an example of a flow of an operation of the remote monitoring apparatus50according to the present second example embodiment is described with reference toFIG.26.

As illustrated inFIG.26, first, the processes of steps S21to S24that are similar to the processes of steps S11to S14inFIG.21according to the first example embodiment described above are performed.

Then, the section display unit54displays divided sections obtained by the section division unit53on a map indicating a movement section of the vehicle10(step S25).

As described above, according to the present second example embodiment, the section display unit54displays divided sections obtained by the section division unit53on a map indicating a movement section of the vehicle10. As a result of this, divided sections that have been obtained to be adapted to geographical characteristics such as a position or a movement direction of the vehicle10in consideration of features of the respective sections can be reported to a monitoring person that monitors the vehicle.

The other effects are similar to effects according to the first example embodiment described above.

Other Example Embodiments

In the first and second example embodiments described above, the remote monitoring apparatus50has divided a movement section of the vehicle10, and has specified a delay jitter distribution in each of the divided sections, but this is not restrictive. The vehicle10may obtain vehicle information from another vehicle10directly or through the remote monitoring apparatus50, and may divide a movement section of the other vehicle10and may specify a delay jitter distribution in each of the divided sections. In this case, it is sufficient if the vehicle10includes components that correspond to the vehicle information reception unit51, the delay jitter specification unit52, and the section division unit53. Furthermore, the vehicle10may monitor another vehicle10, and may control the other vehicle10(for example, the sudden brakes are applied, traveling speed is reduced, or switching is performed from automated driving to remote driving). In this case, it is sufficient if the vehicle10further includes components that correspond to the monitoring unit and the section display unit54that have been described above.

Concept of Example Embodiments

Next, an example of a configuration of a remote monitoring system100that conceptually indicates the remote monitoring systems1and1A according to the first and second example embodiments described above is described with reference toFIG.27.

The remote monitoring system100illustrated inFIG.27includes an observation unit101and a specification unit102.

The observation unit101and the specification unit102may be provided on any of a side of the remote monitoring apparatus50and a side of the vehicle according to the first and second example embodiments described above.

The observation unit101corresponds to the delay jitter specification unit52according to the first and second example embodiments described above. The observation unit101observes traffic in a network that corresponds to a movement section where a mobile object serving as a target to be monitored (for example, a vehicle) moves.

For example, the observation unit101observes delay jitter in each position in the movement section where the mobile object moves, as traffic in a network that performs communication with the mobile object.

The specification unit102corresponds to the section division unit53according to the first and second example embodiments described above. The specification unit102divides the movement section of the mobile object on the basis of the traffic observed by the observation unit101, and specifies a delay jitter distribution in each of the divided sections.

For example, the specification unit102divides the movement section of the mobile object in consideration of the delay jitter distribution in each of the divided sections. More specifically, the specification unit102specifies a delay jitter distribution, and calculates likelihood in each of the divided sections, by using a traffic model in the movement section of the mobile object. Then, the specification unit102divides the movement section in such a way that the total of the likelihoods of the delay jitter distributions in the respective divided sections increases. Note that it is preferable that the traffic model be a model based on a mixed Laplace distribution in which a plurality of Laplace distributions has been mixed.

Furthermore, the remote monitoring system100may further include a display unit that displays the divided sections obtained by the specification unit102on a map indicating the movement section of the mobile object. This display unit corresponds to the section display unit54according to the second example embodiment described above.

Next, an example of a flow of an operation of the remote monitoring system100illustrated inFIG.27is described with reference toFIG.28.

As illustrated inFIG.28, first, the observation unit101observes traffic in a network that corresponds to a movement section where a mobile object serving as a target to be monitored moves (step S31).

Next, the specification unit102divides the movement section of the mobile object on the basis of the traffic observed in step S31(step S32), and specifies a delay jitter distribution in each of the divided sections (step S33).

As described above, by employing the remote monitoring system100illustrated inFIG.27, the observation unit101observes traffic in a network that corresponds to a movement section where a mobile object serving as a target to be monitored moves. The specification unit102divides the movement section of the mobile object on the basis of the observed traffic, and specifies a delay jitter distribution in each of the divided sections. As described above, the movement section of the mobile object is divided, and a delay jitter distribution in each of the divided sections is specified. Therefore, a delay jitter distribution that corresponds to geographical characteristics such as a position or a movement direction of the mobile object can be specified.

Hardware Configurations of Remote Monitoring Apparatus and Remote Monitoring System According to Example Embodiments

Next, a hardware configuration of a computer90that implements the remote monitoring apparatus50according to the first and second example embodiments described above, and the remote monitoring system100according to the concept of the example embodiments described above is described with reference toFIG.27.

As illustrated inFIG.29, the computer90includes a processor91, a memory92, a storage93, an input/output interface (an input/output I/F)94, a communication interface (a communication I/F)95, and the like. The processor91, the memory92, the storage93, the input/output interface94, and the communication interface95are connected by a data transmission line for mutually transmitting or receiving data.

The processor91is an arithmetic processing device such as a central processing unit (CPU) or a graphics processing unit (GPU). The memory92is a memory such as a random access memory (RAM) or a read only memory (ROM). The storage93is a storage device such as a hard disk drive (HDD), a solid state drive (SSD), or a memory card. Furthermore, the storage93may be a memory such as a RAM or a ROM.

The storage93stores programs that achieve functions of components included in the remote monitoring apparatus50and the remote monitoring system100. The processor91executes each of these programs, and therefore each of the functions of the components included in the remote monitoring apparatus50and the remote monitoring system100is achieved. Here, in executing each of the programs described above, the processor91may load these programs into the memory92, and may execute the programs, or may execute the programs without loading the programs into the memory92. Furthermore, the memory92or the storage93also plays a role of storing information or data that is held by the components included in the remote monitoring apparatus50and the remote monitoring system100.

Furthermore, the programs described above can be stored by using various types of non-transitory computer readable media, and can be supplied to a computer (including the computer90). The non-transitory computer readable media include various types of tangible storage media. Examples of the non-transitory computer readable medium include a magnetic storage medium (for example, a flexible disk, a magnetic tape, or a hard disk drive), a magneto-optical storage medium (for example, a magneto-optical disk), a compact disc-ROM (CD-ROM), a CD-recordable (CD-R), a CD-rewritable (CD-R/W), and a semiconductor memory (for example, a mask ROM, a programmable ROM (PROM), an erasable PROM (EPROM), a flash ROM, or a RAM. Furthermore, the programs may be supplied to the computer by various types of transitory computer readable media. Examples of the transitory computer readable medium include an electric signal, an optical signal, and electromagnetic waves. The transitory computer readable medium can supply the programs to the computer via a wired communication line such as electric wires and optical fibers, or a wireless communication line.

The input/output interface94is connected to a display device941, an input device942, a sound output device943, or the like. The display device941is a device that displays a screen that corresponds to drawing data that has been processed by the processor91, such as a liquid crystal display (LCD), a cathode ray tube (CRT) display, or monitor. The input device942is a device that receives an input of an operation performed by an operator, and is, for example, a keyboard, a mouse, a touch sensor, and the like. The display device941and the input device942may be integrated, and may be implemented as a touch panel. The sound output device943is a device that acoustically outputs sound that corresponds to acoustic data that has been processed by the processor91, such as a speaker.

The communication interface95transmits or receives data to/from an external device. For example, the communication interface95performs communication with an external device via the wired communication line or the wireless communication line.

The present disclosure has been described above with reference to the example embodiments, but the present disclosure is not limited to the example embodiments described above. Various modifications that could be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

Furthermore, part or the entirety of the example embodiments described above can also be described as described in the following supplementary notes, but is not limited to the following.

(Supplementary Note 1)

An observation unit configured to observe traffic in a network that corresponds to a movement section where a mobile object moves, the mobile object serving as a target to be monitored; anda specification unit configured to divide the movement section on the basis of the traffic that has been observed, and specify a delay jitter distribution in each divided sectionare included.
(Supplementary Note 2)

The remote monitoring apparatus according to Supplementary Note 1, in which the observation unit observes, as the traffic, delay jitter in each position of the movement section.

(Supplementary Note 3)

The remote monitoring apparatus according to Supplementary Note 1 or 2, in whichthe specification unit performs:dividing the movement section in consideration of the delay jitter distribution in each of the divided sections.
(Supplementary Note 4)

The remote monitoring apparatus according to Supplementary Note 1 or 2, in whichthe specification unit performs:specifying the delay jitter distribution and calculating a likelihood in each of the divided sections, by using a traffic model in the movement section; anddividing the movement section in such a way that a total of the likelihood of the delay jitter distribution in each of the divided sections increases.
(Supplementary Note 5)

The remote monitoring apparatus according to Supplementary Note 4, in which the traffic model is a model based on a mixed Laplace distribution in which a plurality of Laplace distributions has been mixed.

(Supplementary Note 6)

The remote monitoring apparatus according to any one of Supplementary Notes 1 to 5, further including a display unit configured to display each of the divided sections of the movement section on a map indicating the movement section.

(Supplementary Note 7)

The remote monitoring apparatus according to any one of Supplementary Notes 1 to 6, further including a monitoring unit configured to calculate a degree of risk of the mobile object that moves in each of the divided sections, and control the mobile object.

(Supplementary Note 8)

A remote monitoring method including:a first step of observing traffic in a network that corresponds to a movement section where a mobile object moves, the mobile object serving as a target to be monitored; anda second step of dividing the movement section on the basis of the traffic that has been observed, and specifying a delay jitter distribution in each divided section.
(Supplementary Note 9)

The remote monitoring method according to Supplementary Note 8, in which in the first step, delay jitter in each position of the movement section is observed as the traffic.

(Supplementary Note 10)

The remote monitoring method according to Supplementary Note 8 or 9, in whichin the second step,the movement section is divided in consideration of the delay jitter distribution in each of the divided sections.
(Supplementary Note 11)

The remote monitoring method according to Supplementary Note 8 or 9, in whichin the second step,the delay jitter distribution is specified and a likelihood is calculated in each of the divided sections, by using a traffic model in the movement section, andthe movement section is divided in such a way that a total of the likelihood of the delay jitter distribution in each of the divided sections increases.
(Supplementary Note 12)

The remote monitoring method according to Supplementary Note 11, in which the traffic model is a model based on a mixed Laplace distribution in which a plurality of Laplace distributions has been mixed.

(Supplementary Note 13)

The remote monitoring method according to any one of Supplementary Notes 8 to 12, further including a third step of displaying each of the divided sections of the movement section on a map indicating the movement section.

(Supplementary Note 14)

The remote monitoring method according to any one of Supplementary Notes 8 to 13, further including a fourth step of calculating a degree of risk of the mobile object that moves in each of the divided sections, and control the mobile object.

(Supplementary Note 15)

A remote monitoring system including:an observation unit configured to observe traffic in a network that corresponds to a movement section where a mobile object moves, the mobile object serving as a target to be monitored; anda specification unit configured to divide the movement section on the basis of the traffic that has been observed, and specify a delay jitter distribution in each divided section.
(Supplementary Note 16)

The remote monitoring system according to Supplementary Note 15, in which the observation unit observes, as the traffic, delay jitter in each position of the movement section.

(Supplementary Note 17)

The remote monitoring system according to Supplementary Note 15 or 16, in whichthe specification unit performs:dividing the movement section in consideration of the delay jitter distribution in each of the divided sections.
(Supplementary Note 18)

The remote monitoring system according to Supplementary Note 15 or 16, in whichthe specification unit performs:specifying the delay jitter distribution and calculating a likelihood in each of the divided sections, by using a traffic model in the movement section; anddividing the movement section in such a way that a total of the likelihood of the delay jitter distribution in each of the divided sections increases.
(Supplementary Note 19)

The remote monitoring system according to Supplementary Note 18, in which the traffic model is a model based on a mixed Laplace distribution in which a plurality of Laplace distributions has been mixed.

(Supplementary Note 20)

The remote monitoring system according to any one of Supplementary Notes 15 to 19, further including a display unit configured to display each of the divided sections of the movement section on a map indicating the movement section.

(Supplementary Note 21)

The remote monitoring system according to any one of Supplementary Notes 15 to 20, further including a monitoring unit configured to calculate a degree of risk of the mobile object that moves in each of the divided sections, and control the mobile object.

REFERENCE SIGNS LIST

1,1A REMOTE MONITORING SYSTEM10VEHICLE10X MOBILE OBJECT11VEHICLE INFORMATION SPECIFICATION UNIT12VEHICLE INFORMATION TRANSMISSION UNIT20BASE STATION30INTERNET40CLOUD50REMOTE MONITORING APPARATUS51VEHICLE INFORMATION RECEPTION UNIT52DELAY JITTER SPECIFICATION UNIT53SECTION DIVISION UNIT54SECTION DISPLAY UNIT90COMPUTER91PROCESSOR92MEMORY93STORAGE94INPUT/OUTPUT INTERFACE941DISPLAY DEVICE942INPUT DEVICE943SOUND OUTPUT DEVICE95COMMUNICATION INTERFACE100REMOTE MONITORING SYSTEM101OBSERVATION UNIT102SPECIFICATION UNIT