KR20140102371A - Apparatus and Method for Continuous Range Neighbor Queries in Vehicular Ad Hoc Networks - Google Patents

Abstract

The present invention relates to range nearest query processing techniques moving in a vehicular ad hoc network environment. The present invention relates to a technology of detecting a proximity vehicle by creating an ad hoc network environment while the vehicle moves to receive movement information of other vehicles and by calculating the distance of the other vehicles in a user vehicle. The technique can be conveniently used for supporting safe driving by detecting the movement of the proximity vehicle during operation of the vehicle. The present invention provides the position of other vehicles to make a driver to achieve a safe driving by using a resulting value of calculating the distance between a query vehicle and at least one other vehicle in the query range to determine at least one vehicle proximity to the query vehicle.

Description

[0001] The present invention relates to an apparatus and method for processing a nearest neighbor query in a moving area in a vehicle ad hoc network environment,

The present invention relates to a nearest neighbor query processing method for a moving area in a vehicle ad hoc network environment, in which an ad hoc network environment is created while a vehicle is moving, receiving movement information of another vehicle, And a technique for calculating a distance and performing a risk analysis on a nearby vehicle. Such a system can be useful for ensuring traffic safety while driving a vehicle.

The present invention was derived from a research carried out by the Korea Research Foundation and the Ajou University Industrial Research & Development Cooperation (KAIST) as part of the project of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). [Task Number: 2012R1A1A2043422, -k A Study on the Query Processing Algorithm.

With the development of location search and service technologies such as mobile communication network, GPS, etc., various applications utilizing location based services of mobile vehicles have been developed in recent years. In addition, as a means for assisting safe driving of a driver of a vehicle, a system has been proposed in which vehicles on the road are interconnected through an Ad-Hoc network to exchange traffic information.

An ad-hoc network is a network that does not have a fixed wired network but only communicates with a mobile host. It is suitable for constructing a network that is difficult to construct a wired network or used for a short period of time. There is no restriction on the movement of the host, There is a merit that the network configuration is easy and the cost is low.

In the case of the client-server model, which contrasts with the ad-hoc network, it transmits the movement information of the vehicles to the server and provides the results of the server to the vehicles. In this model, There is a problem that the server expansion cost, the maintenance cost, and the communication cost are very high.

On the other hand, ad-hoc network has recently been adapted to various fields due to the configuration of independent networks and the demand for interconnection between various information communication terminals. Especially, utilization of mobile ad-hoc networks in next generation networks is various .

A mobile ad-hoc network is an autonomous and independent network composed solely of mobile terminals without the help of a fixed base network. A mobile terminal in a mobile ad-hoc network is active and is free to participate and depart from the network, and constitutes a network constituting the network equally. This is a feature of mobile ad-hoc compared to the vertical and passive operation of a terminal in a fixed and centralized base network. Such mobile ad-hoc network-based services include conference and group communication services, emergency rescue services, military communication services, and home network services and telematics services that combine ad-hoc network based services with existing services.

Telematics service is a technology that provides comprehensive information service to driver through information terminal (telematics terminal) attached to vehicle. That is, the telematics technology sets the subject of the wireless Internet service as a vehicle that runs on the road, and provides a service such as GPS and GIS based location information, wireless Internet, safety and security of the vehicle, management and entertainment through the telematics terminal attached to the vehicle Lt; / RTI >

A general telematics service is recognized as a communication service between an information center providing information and a vehicle provided with information, but it is also possible to perform information exchange between vehicles through communication devices in the vehicle or through direct communication between the vehicle and the vehicle.

The telematics service based on the ad-hoc communication is also developed as a means for assisting the safe driving by sensing proximity between the vehicles. Such a technique can provide a technical auxiliary countermeasure for a vehicle approaching in a blind spot, which was difficult to cope with in the past by the driver's attention.

As such prior art, Korean Patent No. 10-0677166 entitled " Traffic Information Exchange Device and Method Using Ad Hoc Networking ", traffic information exchange using ad hoc networking, which wirelessly transmits and receives traffic information to and from at least one nearby vehicle, System has been proposed.

In order to prevent the phenomenon that traffic information to be exchanged between the vehicles is flooded and the efficiency of storage and processing is inferior, the prior art has the same direction as the vehicle itself, but the information of the vehicle located in the rear is not helpful for itself. And the like, in order to selectively process the information in consideration of the traveling direction and the position of the adjacent vehicle.

However, according to the above-described prior art, since information is periodically received from all vehicles within a certain distance range and is managed by the vehicles, and since the vehicle itself periodically broadcasts traffic information, excessive information (broadcasting of a frequent message) There is still an overflowing problem.

Therefore, a nearest neighbor query processing technique in an ad-hoc network environment is required as a method for efficiently utilizing limited resource and network characteristics and efficiently sharing necessary information.

Korean Patent No. 10-0677166 (Jan. 26, 2007)

An object of the present invention is to configure an ad hoc network environment of vehicles so as to ensure safe driving / running by checking the movement of nearby vehicles in the vicinity of a query vehicle.

Another object of the present invention is to generate movement information in a vehicle without going through a server or an infrastructure, calculate movement distance information from another vehicle, calculate an estimated distance, and determine an access vehicle position without calculation delay.

The present invention also aims at preventing flooding of excessive information by efficiently transmitting minimum information in an ad hoc network environment.

The present invention also aims to reduce the calculation cost of a query vehicle by presenting an effective criteria for the query vehicle to determine the nearest vehicle.

According to an aspect of the present invention, there is provided an apparatus for processing nearest neighbors in a mobile ad hoc network environment, the apparatus comprising: a movement information receiver for receiving movement information about at least one other vehicle in a query area; An operation unit for calculating a distance between the query vehicle and at least one or more other vehicles in the query area by using the movement information about the received other vehicle; And a first determination unit for determining at least one vehicle closest to the query vehicle using a result of calculating a distance from at least one other vehicle in the query area.

Meanwhile, the nearest neighborhood query processing apparatus in a moving ad hoc network environment according to an embodiment of the present invention further includes a broadcasting unit for broadcasting movement information of the query vehicle itself to at least one or more other vehicles in the query region .

Meanwhile, the nearest neighbors processing apparatus in a moving ad hoc network environment according to an embodiment of the present invention may perform a process of re-casting the received movement information according to the distance from the at least one other vehicle A second determination unit for determining whether or not to perform the determination; And a broadcasting unit for librating the received movement information according to a determination as to whether or not to perform live casting on the received movement information.

Meanwhile, the nearest neighbor query processing apparatus in a moving ad hoc network environment according to an exemplary embodiment of the present invention may include a previous movement information previously broadcasted by the inquiry vehicle and a current position, direction, or velocity information of the query vehicle A third determining unit for determining whether or not the inquiry vehicle is out of a predetermined threshold condition from the previous movement information; And a broadcasting unit for broadcasting updated movement information of the inquiry vehicle to at least one or more other vehicles in the inquiry area when the inquiry vehicle is out of the predetermined threshold condition.

Also, the present invention provides a method for processing nearest neighbor query in a mobile ad hoc network environment, comprising: receiving movement information about at least one other vehicle in a query area; Calculating a distance between the query vehicle and at least one or more other vehicles in the query area using the received movement information about the other vehicle; And determining at least one vehicle closest to the query vehicle using a result of calculating a distance from at least one other vehicle in the query area.

Meanwhile, the method of processing nearest neighbor query in a mobile ad hoc network environment according to an embodiment of the present invention further includes broadcasting the movement information of the query vehicle itself to at least one or more other vehicles in the query area can do.

Meanwhile, according to an embodiment of the present invention, there is provided a method of processing nearest neighbor query in a mobile ad hoc network environment, the mobile proximity query processing method comprising: a step of performing live casting of the received movement information according to a distance from the at least one other vehicle Determining whether or not the image is to be displayed; And librating the received movement information according to a determination of whether to perform a live cast on the received movement information.

Meanwhile, a nearest neighbor query processing method in a moving ad hoc network environment according to an exemplary embodiment of the present invention may include a method of processing a nearest neighbor query in a moving ad hoc network environment, Determining whether the query vehicle has departed from a predetermined threshold condition from the previous movement information based on the previous movement information; And broadcasting the updated movement information of the inquiry vehicle to at least one or more other vehicles in the inquiry area when the inquiry vehicle is out of the predetermined threshold condition.

According to the present invention, because the calculation is performed inside the vehicle, it is possible to construct a system without the help of a central server or an infrastructure, thereby reducing costs. Also, according to the present invention, it is possible to easily identify the location of vehicles that are not easily visible due to trees, buildings, and other vehicles, and can be applied as a traffic accident prevention system.

According to the present invention, there is provided a method for relaying / re-broadcasting stochastic data with a distance value calculated using movement information of each vehicle and adjacent vehicles as a measure against data omission due to an obstacle or communication failure in an ad hoc network environment The frequency of frequent data transmission can be minimized.

Further, according to the present invention, since the direction and speed of the moving information are provided to the driver by detecting the vehicle close to the own vehicle, safe driving / driving can be achieved by appropriately determining the vehicle in the invisible area.

According to the present invention, by using the movement information (speed, position, time information) instead of the simple position information of the vehicles, it is possible to more efficiently process the query for the nearest neighboring vehicle. Further, according to the present invention, it is possible to reduce the calculation cost of a query vehicle by presenting an effective criterion for a query vehicle to process a query for a nearest vehicle.

1 is a diagram conceptually showing a vehicle ad hoc network environment in which a nearest neighbor query process is performed according to an embodiment of the present invention.
2 is a conceptual block diagram illustrating a nearest neighbor query processing apparatus in a mobile ad hoc network environment according to an embodiment of the present invention.
3 is a flowchart illustrating a method for processing a nearest neighbor query in a moving area in a vehicle ad hoc network environment according to an embodiment of the present invention.
FIG. 4 is a flowchart illustrating a process for determining whether to relay or broadcast using a calculated distance value in a nearest neighbor query processing method in a moving area according to an exemplary embodiment of the present invention. Referring to FIG.
5 is a conceptual diagram illustrating a process of determining a vehicle closest to a query vehicle based on a calculated distance result value according to an embodiment of the present invention.
6 is an operational flowchart showing a criterion for again determining a vehicle closest to a query vehicle in a method of processing nearest neighbor query in a moving area according to an embodiment of the present invention.
7 is an operational flowchart showing a criterion for re-broadcasting movement information of a query vehicle in a nearest neighbor query processing method in a moving area according to an embodiment of the present invention.
8 is a diagram conceptually illustrating a process of calculating distances between mobile entities in the nearest neighbor query processing method of the present invention.
9 is a diagram conceptually showing various embodiments for comparing with the existing proximity query processing result using movement information received from a new vehicle in the proximity query processing method of the present invention.
10 is a diagram conceptually illustrating a process of determining whether a query vehicle itself is out of a threshold condition in a nearest neighbor query processing method in a moving area according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In the following description of the embodiments of the present invention, specific values are only examples. The present invention is not limited to or limited by the embodiments.

1 is a diagram conceptually showing an inter-vehicle ad hoc network environment in which the nearest neighbor query processing of the present invention is performed.

The present invention provides a technique for detecting a risk of access to a nearby vehicle by calculating a distance between vehicles using a predetermined space using ad hoc communication.

Referring to FIG. 1, Q represents a query user's vehicle, that is, a query vehicle. A to G means other vehicles. For example, Q moves to the left, and the unit velocity is 1. It is assumed that the query vehicle Q grasps the position and speed information of the vehicles A to G at the present time. If we perform a k-nearest neighbor query (k = 2) that searches for the closest two vehicles around the query vehicle Q, B and C will be obtained at the current point tcur.

This closest query processing can be expressed as follows. The processing result is R = {<I, R _I > | <[tcur, tcur + 1], {B, C}>, <[tcur + 1, tcur + 2], and {A, C}>. Assuming that the meaning of the process results in the current speed and direction, B and C are the closest two vehicles during [tcur, tcur + 1] and A and C during tcur + 1, tcur + 2 Indicating the closest two vehicles. This is because the vehicle B moves at a relatively fast unit speed of 2 (because it is moving away from the query vehicle Q) as compared to the query vehicle Q and the vehicle C.

<Description of Device>

2 is a conceptual block diagram illustrating a nearest neighbor query processing apparatus in a mobile ad hoc network environment according to an embodiment of the present invention.

Referring to FIG. 2, a nearest neighbor query processing apparatus in a mobile ad hoc network environment according to an embodiment of the present invention can be mounted on a moving query vehicle. The nearest neighbor query processing apparatus includes a movement information receiving unit (100), a calculating unit (110), and a first determining unit (120).

The proximity query processing apparatus may further include a second determination unit 130, a third determination unit 140, and a broadcasting unit 150 according to an embodiment.

The movement information receiving unit 100 receives movement information about at least one or more other vehicles in the query area.

At this time, the movement information may include an ID of at least one or more other vehicles in the inquiry area, position and velocity information for a specific time. That is, the movement information may further include speed information as well as position information that a specific vehicle has at a specific time. Velocity is a concept that includes direction and speed.

The calculating unit 110 calculates the distance between the query vehicle and at least one or more other vehicles in the query area using the received movement information about the other vehicle.

At this time, the calculation unit 110 may calculate the distance between the vehicles by accurately grasping the actual position of the other vehicle in real time, but according to another embodiment, using the previously received movement information, May be estimated as a moving region including a certain error range. According to this embodiment, the calculating unit 110 may calculate the distance between the vehicles using the distance between the centers of the estimated moving area.

The first determination unit 120 determines at least one vehicle closest to the query vehicle using the result of calculating the distance to at least one other vehicle in the query area.

At this time, the process of determining the at least one vehicle closest to the query vehicle may be performed periodically, but may be performed only when the first determination unit 120 detects that a new vehicle has entered the query area. At this time, the number of the at least one nearest vehicle determined by the first determination unit 120 may be a predetermined number such as k. A query that conventionally finds k closest vehicles is called a k-nearest neighbor query (k-NN).

The second determining unit 130 determines whether to use the result of the calculation of the distance from the at least one or more other vehicles by the calculating unit 110 to perform librocasting of the received movement information of the other vehicle. At this time, rib-casting is a process of relaying and redistributing movement information of other vehicles. That is, the position of the vehicle that transmitted the movement information is calculated from the received movement information, and the movement information is relayed according to the distance from the originating vehicle to redistribute it to other vehicles. In the case where a particular vehicle distributes its movement information, some vehicles in the query area may not receive movement information due to a network failure or obstacle. Therefore, by redistributing the mobile information with the vehicles receiving the mobile information message, it is possible to increase the probability of being appropriately transmitted to the vehicles that should receive the mobile information.

However, if all the vehicles receive information and rebroadcasting at this time, there may be a problem of overlapping information flooding. Therefore, in the present invention, a criterion for redistributing movement information of another vehicle is also presented.

The third determination unit 140 determines whether or not the query vehicle is out of the predetermined threshold condition from the previous movement information based on the previous movement information previously broadcasted by the query vehicle and the current position, . The present invention introduces a threshold condition in which update broadcasting is performed for movement information in order to reduce the frequency with which vehicles broadcast the movement information. The critical condition will be described in detail with reference to FIG. 7 and FIG. 10 below.

The broadcasting unit 150 broadcasts movement information of the query vehicle itself to at least one or more other vehicles in the query area.

When the broadcasting unit 150 detects that a new vehicle has entered a predetermined critical region, the broadcasting unit 150 may broadcast movement information of the query vehicle. In addition, when it is determined to perform live casting / redistribution of the movement information received by the second determination unit 130, the broadcasting unit 150 can perform live casting / redistribution of the received movement information.

In addition, when it is determined by the third determination unit 150 that the query vehicle is out of a predetermined threshold condition, the broadcasting unit 150 transmits the updated movement information of the query vehicle to at least one or more other vehicles in the query region . &Lt; / RTI &gt;

On the other hand, the query region means a region which is a basic premise of a nearest neighbor query to find at least one nearest vehicle, and the critical region is a region in which the query processing apparatus of the present invention is a criterion for broadcasting the movement information of the new entry vehicle Area. Depending on the embodiment, the query area and the threshold area may be set differently, but the query area and the threshold area may be set in the same range.

<Description of Method>

3 is a flowchart illustrating a method for processing a nearest neighbor query in a moving area in a vehicle ad hoc network environment according to an embodiment of the present invention.

Referring to FIG. In a nearest neighbor query processing method according to an embodiment of the present invention, movement information about at least one other vehicle in a query area is received (S210), distance from another vehicle is calculated using movement information about another vehicle S220), and determining (S230) at least one vehicle closest to the query vehicle using the distance calculation result with the other vehicle.

1. Receiving movement information for at least one or more other vehicles in the query area < S210 >

In step S210, the movement information receiving unit 100 receives movement information on at least one or more other vehicles in the query area.

At this time, the movement information may include an ID of at least one or more other vehicles, a position for a specific time, and speed information.

2. Calculate the distance to another vehicle using the movement information of the other vehicle <S220>

In step S220, the calculating unit 110 calculates the distance between the query vehicle and at least one or more other vehicles in the query area using the movement information about the other vehicle.

In this case, the process of calculating the distance between the vehicles (S220) may be based on the actual positions of the two vehicles, but may be based on the estimated positions of the two vehicles according to the embodiment. The calculation unit 110 can estimate the movement information at the current time and the movement area having a certain error range based on the movement information at the previous time of the two vehicles.

This process can be described in detail with reference to FIG. 8 is a diagram conceptually illustrating a process of calculating distances between mobile entities in the nearest neighbor query processing method of the present invention.

8, the actual distance between the actual vehicle positions A and B at time T is represented by ActDist (A, B, T), and the estimated distance may be expressed as EstDist (A, B, T).

The operation unit 110 can estimate the estimated positions p _A and p _B of A and B based on the movement information of A and B before T. [ In addition, we can estimate the moving region of A and the moving region of B with a certain radius d _TH around the estimated positions p _A and p _B.

The estimated distance can be calculated by the distance between p _A and p _B , and the relationship between the estimated distance and the actual distance satisfies Equation (1).

[Equation 1]

EstDist (A, B, T) - 2 * dTH = ActDist (A, B, T)

The exact distance between A and B should be obtained by the actual distance ActDist (A, B, T), but in order to know the actual distance accurately, it is necessary to determine the actual positions of A and B, You need to know the information. However, such periodic or real-time location detection frequently generates movement information and can cause flooding of information. Therefore, in order to reduce computation cost and prevent overflow of information through message transmission, desirable. In the following description, the process of calculating the distance is regarded as using either the actual distance or the estimated distance.

At this time, the process of calculating the distance from the movement information can be expressed by the following equations (2) and (3).

&Quot; (2) &quot;

,

,

Here, V _Ax is the X component value of the speed of the vehicle A, V _Bx is the X component value of the speed of the vehicle B, V _Ay is the Y component value of the speed of the vehicle A, and V _By is the Y component value of the speed of the vehicle B it means. Thus, the values of a _x and a _y can be obtained by using the x and y components of the velocities of the vehicles A and B, respectively.

In addition, the loc (t1) _Ax and loc (t1) _Ay are X, Y position values, loc (t2) _Bx and loc (t2) _By the vehicle A to the time t1 is the vehicle for t2 time B in Equation 2 X, Y position value.

Accordingly, Equation (2) can be summarized as Equation (3).

&Quot; (3) &quot;

Equation (3) summarizes the elements of Equation (2) and derives the quadratic equation for the time (T) of the query vehicle (A) and at least one or more other vehicles (B).

The distance calculation in the calculation unit 110 can be performed using Equation (3).

At this time, the second determination unit 130 determines whether to broadcast the received movement information of another vehicle according to the distance between the calculated query vehicle and at least one or more other vehicles (S310).

FIG. 4 is a flowchart illustrating a process for determining whether to relay or broadcast using a calculated distance value in a nearest neighbor query processing method in a moving area according to an exemplary embodiment of the present invention. Referring to FIG.

Referring to FIG. 4, the second determination unit 130 determines whether to libro cast the movement information according to the distance from the other vehicle that transmitted the movement information (S310). The broadcasting unit 150 may broadcast movement information of another vehicle according to the determination (S320).

In step S310, the second determining unit 130 determines whether the rib-casting is to be performed using the distance-based probability as a result of calculating the distance between the query vehicle and at least one or more other vehicles, (Distance-based Stochastic Rebroadcst).

Accordingly, the distance-based probability can be expressed by Equation (4).

&Quot; (4) &quot;

In Equation 4 P _rebroadcast the redistribution rate (rib de casting), V _rcv will query the vehicle, V _src other vehicle transmitting the movement information, rpt _vsrc the movement information of the vehicle V _SRC, R _BC advance of the set query region The radius, dist (V _rcv , V _src ), represents the distance between V _rcv and V _src , and the second decision unit 130 probabilistically ribs the movement information of V _SRC using Equation (4) .

According to Equation (4), when there is the vehicle V _SRC that generated and distributed the movement information rpt _vsrc and the query vehicle V _RCV that received the information, the probability that V _RCV redistributes the movement information is the vehicle V _SRC and the query vehicle V _RCV The closer the distance, the higher the distance, and the closer the distance, the lower.

On the other hand, when the distance between the vehicle V _SRC and the query vehicle V _RCV is larger than the radius R _BC of the query area, the _VBRV does not need to pay attention to the movement information of the vehicle V _SRC ,

3. Determining at least one vehicle closest to the query vehicle using the result of distance calculation with another vehicle < S230 >

In step S230, the first determination unit 120 determines the at least one vehicle closest to the query vehicle using the result of calculating the distance to at least one other vehicle in the query area. It is already mentioned that, when k vehicles closest to the query vehicle are determined, they are also referred to as k-nearest queries. A method of processing a k-nearest neighbor query based on a query vehicle will be described with reference to FIG. 5 and FIG.

5 is a conceptual diagram illustrating a process of determining a vehicle closest to a query vehicle based on a calculated distance result value according to an embodiment of the present invention.

Referring to FIG. 5, in step S220, a graph showing the result of the calculation using the quadratic equation for the time T as shown in Equation (3) with respect to the time T is shown. 5, the X axis represents time T, the Y axis represents the distance between the query vehicle and at least one or more other vehicles, and G _B , G _C , and G _D represent distances between the query vehicle and vehicles B, C, and D.

The graph of FIG. 5 is shown in order to facilitate understanding of the k-nearest neighbor query process of the present invention. Actually, in the query processing apparatus of the present invention, the quadratic equation is calculated by using a quadratic equation By calculating the distance between vehicles B, C and D, k vehicles closest to Q can be determined for each time.

In this case, we calculate the intersection where the values of the distances G _B , G _C , and G _D between the query vehicle Q and the respective vehicles cross each other, and calculate a continuous time interval in which the result of the k- .

For example, in a continuous time interval between start time t0 and t2, vehicle B and vehicle C are closest to Q, and after t2, vehicle C and vehicle D are closest to Q.

6 is an operational flowchart showing a criterion for again determining a vehicle closest to a query vehicle in a method of processing nearest neighbor query in a moving area according to an embodiment of the present invention.

Referring to FIG. 6, the first determination unit 120 of the query processing apparatus of the present invention can recalculate and determine the closest k vehicles when it detects that a new vehicle has entered a query area (S510). At this time, the fact that a new vehicle has entered can be grasped by receiving movement information of other vehicles.

In another embodiment of the present invention not shown, the first determination unit 120 may periodically recalculate the closest k vehicles.

9 is a diagram showing various embodiments of a k-proximity query process when a new vehicle enters in the query processing method of the present invention.

Referring to FIG. 9, the relative distances to a plurality of the nearest vehicles identified in the prior art are shown in the form of a graph with respect to time T. FIG. At this time, if k = 3, the corresponding D _kth graph may be a graph showing the distance from the query vehicle to the third distance from the query vehicle.

9 (a), the intersection of the quadratic curve r _B (which can be calculated using Equation 3), which is a distance graph between the newly entered vehicle B and the query vehicle, and the D _kth graph exists at t 1 and t 2 on the time axis Is shown.

Therefore, the existing query result is maintained as it is from the current point of sp _cur to t 1, but from t 1 to t 2, the newly entered vehicle B is newly added to the query result and replaces any other existing vehicle.

On the other hand, in FIG. 9 (b), since the distance from the vehicle B to the vehicle B is steadily larger than the distance from the existing k-nearest-neighbor processing vehicles to sp _cur to sp _next , B does not replace the existing k- Or, if it was included in the previous query result, replace it with another node in the query result.

Figure 9 (c) takes place in a comparison of the distance D of the vehicle C and the _kth query vehicle distance rC and existing between the nearest vehicle. At times t3 and t4, the vehicle C is included in the nearest k vehicles.

In Fig. 9 (d), the vehicle C is farther away from the query vehicle than the constant D _kth on the segments sp _cur , sp _next , so that it does not affect the results of the conventional closest query.

7 is an operation flowchart showing a condition for re-broadcasting movement information of a query vehicle itself in a query result processing method according to an embodiment of the present invention.

Referring to FIG. 7, in step S210, movement information of another vehicle is received.

If it is detected from the received movement information that a new vehicle has entered the critical area (S610), the broadcasting unit 150 broadcasts the movement information of the query vehicle itself again (S630). This process is performed for the purpose of helping the safe driving of the newly entered vehicle by informing the newly entering vehicle of the movement information of the inquiry vehicle itself.

Further, other vehicles in the query area or the critical area may also provide an opportunity to update the nearest vehicle by processing the nearest neighbor query again based on the updated movement information of the query vehicle. On the other hand, the query area means a radius which is a basic premise of a query for searching for a nearest vehicle, and the critical area means a reference radius for a query vehicle to broadcast its movement information. Depending on the embodiment, the critical region and the query region may be the same or both may be larger.

The third determination unit 140 compares the movement information previously broadcasted by the query vehicle with the current position and velocity information to determine whether the query vehicle is out of the threshold condition (S620). At this time, if it is determined that the query vehicle is out of the threshold condition, the broadcasting unit 150 may broadcast the movement information of the current query vehicle to inform other vehicles.

10 is a diagram conceptually showing a threshold condition for updating movement information of a query vehicle itself in a query processing method according to an embodiment of the present invention.

Referring to Fig. 10, there is shown a case where the query vehicle Q deviates from the threshold condition and stays in the threshold condition.

The query vehicle Q is able to grasp its own position and speed information at the current time point tcur. At the present time tcur, the query vehicle Q broadcasts its movement information (including position, speed, and direction information) and informs the surrounding vehicles.

The boundary region formed by the critical condition means a region separated by a radius d _TH from the estimated center position in consideration of the position and speed of the previous movement information, and is shown in a circle in FIG. a boundary area after unit time 1 has elapsed since tcur, a boundary area after unit time 2 has elapsed, and a boundary area after unit time 3 has elapsed.

From the movement information of Q broadcasted at time tcur, other vehicles estimate that Q continues to travel in the same direction. At this time, the querying vehicle Q determines whether the current position of the querying vehicle Q is in a negligible range from the estimated position of other vehicles in consideration of the moving speed of the querying vehicle Q.

At this time, the radius d _TH of the boundary region can be given in consideration of the moving speed of the query vehicle itself. Specifically, the radius d _TH can be calculated as shown in Equation (5) below.

&Quot; (5) &quot;

In equation (5), la up to the border area of a mobile information d _{max _ th,} the maximum speed setting Vel _ff the (free flow velocity, the maximum speed), Vel the moving speed of the current query the vehicle, the current critical section d _TH, and Accordingly, if the driver of the query vehicle sets Vel _ff (maximum speed) to 100 km / h and sets d _{max_th} (maximum boundary area) to 5 m, d _TH (current boundary area) is determined according to the current vehicle Vel do.

Therefore, if the moving speed of the query vehicle Q is fast, the critical condition for updating the movement information of the query vehicle becomes large. On the contrary, if the moving speed of the query vehicle is low, the critical condition becomes small.

In FIG. 10, since the unit time 1 has elapsed since the current time point tcur, the threshold condition is 5 m and the query vehicle Q satisfies the threshold condition, so no update broadcasting is performed.

After the unit time 2 has elapsed, the update vehicle is not broadcast because the position of the query vehicle Q is still within the critical condition 4m.

Since the query vehicle Q is out of the threshold condition 2m after the elapse of the unit time 3, an update broadcast is made to the movement information of the query vehicle Q. [

The nearest neighbor query processing method in a mobile ad hoc network environment according to an exemplary embodiment of the present invention may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Various modifications and variations may be made thereto by those skilled in the art to which the present invention pertains.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

100: movement information receiving unit 110:
120: first decision unit 130: second decision unit
140: third determining unit 150: broadcasting unit

Claims (17)

A movement information receiver for receiving movement information about at least one or more other vehicles in a query area;
An operation unit for calculating a distance between the query vehicle and at least one or more other vehicles in the query area by using the movement information about the received other vehicle; And
A first determination unit for determining at least one vehicle closest to the query vehicle using a result of calculating a distance to at least one other vehicle in the query area;
Lt; RTI ID = 0.0 &gt; a &lt; / RTI &gt; mobile ad hoc network environment, The method according to claim 1,
Wherein the first determination unit comprises:
Determining at least one vehicle closest to the query vehicle when it detects that a new vehicle has entered the query area
Wherein the mobile node is in a mobile ad hoc network environment. The method according to claim 1,
The operation unit,
Estimating a moving region of the received other vehicle using the received moving information about the other vehicle, calculating a distance between the query vehicle and the at least one or more other vehicles by using the distance between the centers of the estimated moving region Operation
Wherein the mobile node is in a mobile ad hoc network environment. The method according to claim 1,
A broadcasting unit for broadcasting movement information of the inquiry vehicle itself to at least one or more other vehicles in the inquiry area;
Further comprising: means for determining a location of the mobile node in the mobile ad hoc network environment. 5. The method of claim 4,
The broadcasting unit includes:
Broadcasting movement information of the query vehicle when it detects that a new vehicle has entered a predetermined critical area
Wherein the mobile node is in a mobile ad hoc network environment. The method according to claim 1,
Wherein the movement information receiver comprises:
Receiving movement information including an ID (ID) of at least one or more other vehicles in the inquiry area, a position for a specific time, and velocity information
Wherein the mobile node is in a mobile ad hoc network environment. The method according to claim 1,
A second determining unit determining whether to libro cast the received movement information according to a distance from the at least one other vehicle from which the movement information is received; And
And a broadcasting unit for performing a libro casting of the received movement information in accordance with a determination as to whether or not to perform the libro casting of the received movement information,
Further comprising: means for determining a location of the mobile node in the mobile ad hoc network environment. The method according to claim 1,
Determining whether or not the query vehicle has deviated from a predetermined threshold condition from the previous movement information based on previous movement information previously broadcasted by the query vehicle and current position, direction, or velocity information of the query vehicle; 3 crystal part; And
A broadcasting section for broadcasting updated movement information of the inquiry vehicle to at least one or more other vehicles in the inquiry area when the inquiry vehicle is out of the predetermined threshold condition,
Further comprising: means for determining a location of the mobile node in the mobile ad hoc network environment. Receiving movement information for at least one or more other vehicles in the query area;
Calculating a distance between the query vehicle and at least one or more other vehicles in the query area using the received movement information about the other vehicle; And
Determining at least one vehicle closest to the query vehicle using a result of calculating a distance to at least one other vehicle in the query area;
A method for processing a nearest neighbor query in a moving area in a vehicle ad hoc network environment 10. The method of claim 9,
Wherein the step of determining at least one vehicle closest to the query vehicle comprises:
Determining at least one vehicle closest to the query vehicle when it detects that a new vehicle has entered the query area
And a method for processing nearest neighbor queries in a moving area in a vehicle ad hoc network environment. 10. The method of claim 9,
The step of calculating the distance to the other vehicle includes:
Estimating a moving region of the received other vehicle using the received moving information about the other vehicle; And
Calculating a distance between the query vehicle and the at least one or more other vehicles using a distance between centers of the estimated moving area
And a method for processing nearest neighbor queries in a moving area in a vehicle ad hoc network environment. 10. The method of claim 9,
Broadcasting the movement information of the query vehicle itself to at least one or more other vehicles in the query area;
The method comprising the steps of: receiving a query from a mobile ad hoc network; 13. The method of claim 12,
Wherein the broadcasting comprises:
Broadcasting movement information of the query vehicle when it detects that a new vehicle has entered a predetermined critical area
And a method for processing nearest neighbor queries in a moving area in a vehicle ad hoc network environment. 10. The method of claim 9,
Wherein the step of receiving the movement information comprises:
Receiving movement information including an ID (ID) of at least one or more other vehicles in the inquiry area, a position for a specific time, and velocity information
And a method for processing nearest neighbor queries in a moving area in a vehicle ad hoc network environment. 10. The method of claim 9,
Determining whether to libro cast the received movement information according to a distance from the at least one other vehicle from which the movement information was received; And
Casting the received movement information according to a determination of whether to perform a live cast on the received movement information
The method comprising the steps of: receiving a query from a mobile ad hoc network; 10. The method of claim 9,
Determining whether the query vehicle is out of a predetermined threshold condition from the previous movement information based on previous movement information previously broadcasted by the query vehicle and current position, direction, or velocity information of the query vehicle; ; And
Broadcasting the updated movement information of the query vehicle to at least one or more other vehicles in the query area if the query vehicle is out of the predetermined threshold condition
The method comprising the steps of: receiving a query from a mobile ad hoc network; A computer-readable recording medium having recorded thereon a program for executing the method according to any one of claims 9 to 16.

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