WO2014010801A1

WO2014010801A1 - Distribution method for continuous monitoring of k-nearest neighbor queries in limited area of road network

Info

Publication number: WO2014010801A1
Application number: PCT/KR2012/011834
Authority: WO
Inventors: 조형주; 정태선; 권혁인
Original assignee: 아주대학교산학협력단
Priority date: 2012-07-12
Filing date: 2012-12-31
Publication date: 2014-01-16
Also published as: KR20140010496A; KR101421671B1

Abstract

The present invention relates to a distribution method for the continuous monitoring of k-nearest neighbor queries, and more particularly, to a method and apparatus for analyzing query results from a server which receives a request for information on an object on an active road on which a client terminal exists in a limited area of a road network. The present invention pertains to developing a scheme for a client terminal to perform some jobs performed by the server, while excluding a scheme in which the server processes an entire procedure including distance calculation for a terminal and an arbitrary object as well as query handling. By means of said distribution method, calculation costs of the server can be reduced and communication costs between the client and the server can be reduced.

Description

Distributed Technique for Continuous Monitoring of ｋ-Nearest Queries in Restricted Areas of Road Networks

The present invention relates to a distributed technique for continuous monitoring of k-nearest queries. More particularly, the present invention relates to a query result of a server that is requested for information about an object on an active road where a client terminal is staying in a limited area of a road network. It relates to a method and an apparatus for analyzing.

The present invention is derived from the research conducted as part of the 2nd stage BK project of the Ministry of Education, Science and Technology and the Ministry of Education of Ajou University. [Task Management Number: Nuclear C9A1915, Project Name: ISA SAP100.11 Positive system].

With the development of location search and service technologies such as mobile communication networks, GPS, and the like, in recent years, interest in applications that support location-based services of mobile objects has increased. The location-based service of a mobile object requires K-nearest neighbor search to efficiently retrieve the location information of static objects such as mobile objects and gas stations.

A database storing road network information, moving object information, and static object information is called a road network database. In a road network database, a road network is modeled as a directional graph.

One road segment corresponds to the edge of the graph, and a point where two different road segments meet is a node of the graph.

In addition, facilities such as stops, schools, hotels, etc. on the road network are modeled as static objects, and objects with mobility such as cars and people are modeled as moving objects.

Queries used in the road network database include k-nearest neighbor queries, range queries, and spatial join queries.

In the existing Euclidean space, the Euclidean distance between two objects can be calculated using the absolute position of any two objects. However, in a road network space, a moving object can only move over a predefined road network, so the network distance between the objects cannot be calculated only by the absolute position of the object. Here, the network distance between two objects is the total sum of road segment lengths existing on the shortest path between any two objects in the road network.

In other words, even if the absolute position is the same, the distance varies depending on the situation of the network connecting the two points. Therefore, the network distance between any two points cannot be calculated using only the absolute position of the two points. Various methods for efficient network distance have been studied. Typical examples include IER, INE, and VN.

As such, an example of the related art for a network calculation method that can increase the efficiency in the development of calculating the distance between two objects is disclosed in Korean Patent No. 10-1025360 "Searching for the shortest path for k-nearest neighbor search on road network. Method and apparatus. It was derived with the purpose of searching for at least one static object located within a predetermined distance from a query point on the road network to determine at least one or more destination nodes corresponding to it, and calculating the shortest distance between the static object and the destination.

However, even in the prior art, there is a problem in that the calculation cost of the server increases and the communication cost between the client and the server increases by dedicating all calculations in the server in the method of calculating the shortest distance.

The present invention was derived to solve the problems of the prior art as described above, and among the various methods for efficiently obtaining the conventional network distance, the IER technique uses the property that the Euclidean distance is always less than or equal to the network distance. First, candidates are found based on Euclidean distance, and the actual network distance is obtained only from them. Although it has the advantage of low storage space overhead, the performance of query processing is greatly reduced due to the multiple trials and errors.

The INE technique also searches for the presence of static objects by extending the road segment from the query point. Like the IER technique, it has the advantage of low storage space overhead, but poor query processing performance because of the large number of disk accesses required. The VN method divides the entire network space into a set of cells based on points where the distance between each static object and another adjacent static object is the same. For efficient query processing, the distance between all static objects, nodes, and cell boundaries within each cell is pre-computed.

In addition, the VN technique has better query processing performance than the IER technique and the INE technique, but has a disadvantage of excessive storage space overhead.

Accordingly, the present invention is a way to develop a method for performing a part of the work performed by the server in the client terminal, apart from the way that the server processes not only the query processing but also the entire process including the distance calculation for the terminal and any object. will be. Through this distributed technique, it is intended to reduce the computational cost of the server and to reduce the communication cost between the client and the server.

In order to achieve the above object, the client terminal according to an embodiment of the present invention includes an object information request unit, query result operation unit, the server includes a request message receiving unit, query operation unit, transmission unit.

The object information request unit of the client terminal transmits a message requesting the server for information about an object on the active road where the terminal is staying and a result of a query at both intersections of the active road.

In addition, the query result calculating unit calculates a result when a query is made at an arbitrary point on the active road based on the information about the object on the active road received from the server and the result when the query is made at both intersections of the active road. Analyze

The request message receiving unit of the server receives a request message from the client terminal about the object on the active road where the client terminal is staying and the result of the query when the query is made at both intersections of the active road.

Also, the query calculating unit calculates a result when a query is made at both intersections of the active road using object information on a road connected to both intersections of the active road.

In addition, in response to the request message, the transmission unit transmits the information about the object on the active road where the client terminal is staying and the result when a query is made at both intersections of the active road to the client terminal.

Through this process, the apparatus (terminal, server) and the method for analyzing the k-nearest query result of the present invention share the operation for the server and the client to interpret the k-nearest query. On the other hand, the server provides the client terminal with a minimum of necessary information required for the client to perform and interpret the k-nearest query at any point in advance to the client terminal, the client terminal using the information provided from the server Complete the k-nearest query process for the point.

According to the present invention, since the load of the server does not increase greatly even if the number of client terminals is increased by using a distributed algorithm, it is possible to reduce the additional cost of additional servers to withstand the peak time load. That is, according to the present invention, since the client shares a part of the calculation work of the server and processes it, the load of the server is distributed.

In addition, since the query result is requested to the server only when the client terminal crosses the intersection, the communication cost between the client terminal and the server is reduced. In addition, the number of communication and the amount of communication data between the client terminal and the server is reduced, thereby reducing the load on the network and minimizing the influence on the communication of other users.

In addition, while the conventional techniques use the straight distance as the shortest distance, the present invention has an effect of continuously calculating the shortest distance desired by the client terminal by continuously grasping the POI and traffic flow around the client.

1 shows a conceptual configuration of a client terminal according to an embodiment of the present invention.

2 shows a conceptual configuration of a server according to an embodiment of the present invention.

3 illustrates a configuration of a server to which a moving path predictor is added according to an embodiment of the present invention.

4 is a flowchart illustrating a method of analyzing a k-nearest query result in a client terminal according to an embodiment of the present invention.

5 is a flowchart illustrating a method for requesting object information from a server when a client terminal enters an intersection of one of active roads according to an exemplary embodiment of the present invention.

FIG. 6 is a flowchart illustrating a request for object information on a server other than an active road when the client terminal enters an intersection of one of the active roads according to an embodiment of the present invention.

7 is a flowchart illustrating a shortest path that a client terminal may actually access according to an embodiment of the present invention.

8 is a flowchart illustrating a k-nearest query in a server according to an embodiment of the present invention.

9 is a flowchart illustrating a pre-calculation of a query result even when a server does not receive a request message from a terminal according to an embodiment of the present invention.

10 is a flowchart illustrating a precomputation of a query result by predicting a moving path of a terminal in a server according to an embodiment of the present invention.

11 illustrates an embodiment of a k-nearest query in the client terminal of the present invention.

12 illustrates a conceptual structure of a communication state between a client terminal and a server according to an embodiment of the present invention.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

However, the present invention is not limited or limited by the embodiments. Like reference numerals in the drawings denote like elements.

In the continuous monitoring technique of the k-nearest query, the terminal 100 includes an object information requesting unit 110 and a query result calculating unit 120. At this time, the terminal 100 can be applied to a mobile phone, navigation, smart phone.

The object information requesting unit 110 transmits a message requesting the server for information about an object on the active road on which the terminal 100 is staying and a result when a query is made at both intersections of the active road. In this case, when the terminal enters the intersection of either side of the active road, it may transmit a message requesting the server the result of the query to the server. At this time, the road on which the terminal 100 stays is called an active road.

In addition, when the terminal 100 enters an intersection of any one of the active roads, the terminal 100 may request information about an object on at least one road connected to the intersection.

In addition, when the terminal 100 enters an intersection of either side of the active road, the server 200 displays information on an object on the other road except for the active road where the terminal was previously located among at least one road connected to the intersection. May be required.

At this time, the information requested by the terminal 100 and provided by the server 200 may be information about a proximity object when the k-nearest query is performed at the intersection where the road branches. In response to the query of 100), not only the information about the stationary object in the active road, but also the k-nearest query result at both endpoints of the active road are notified together, so that the final k-nearest query result of the terminal 100 is reported. I can complete it.

The query result calculating unit 120 calculates a result when a query is made at an arbitrary point on the active road based on the information about the object on the active road received from the server and the result of the query at both intersections of the active road. Analyze In this case, the result of querying at any point on the active road may be analyzed in consideration of the shortest path that can be actually accessed, such as traffic conditions and road conditions.

In addition, the result of the query at the current position of the terminal 100 may be analyzed. In this case, any point mentioned above may be interpreted to mean the current location of the terminal 100. That is, the terminal 100 processes the k-nearest query result (preliminary k-nearest query result for a preselected and fixed point) provided from the server 200, and the terminal 100 changes from time to time while driving. The k-nearest query result can be interpreted in real time for the position of 100).

In addition, according to another embodiment of the present invention, by selecting the user of the terminal 100, instead of the position of the terminal 100 changes in real time, by selecting any point that the user wants to reach, The k-nearest query result based on the point may be searched to guide the user's moving path. Of course, in this case, since the information that the terminal 100 can receive from the server 200 may be limited to information within a certain range centering on the location of the current terminal 100, such a function may be limited to that of the terminal 100. This may be more useful when the location is approached within a certain range of the user's final target point.

The server 200 includes a request message receiver 210, a query operator 220, and a transmitter 230.

The request message receiving unit 210 receives a request message from the terminal 100 about the object on the active road on which the terminal 100 is staying and the result of a query at both intersections of the active road.

The query calculating unit 220 calculates a result when a query is made at both intersections of the active road using object information on a road connected to both intersections of the active road. At this time, before receiving the request message about the information on the object on the active road in which the terminal 100 is staying and the result of the query at both intersections of the active road from the terminal 100, the intersection around the active road You can also precompute the query result.

The transmitter 230 responds to a request message for information about an object on an active road on which the terminal 100 is staying and a result when a query is made at both intersections of the active road, and the terminal 100 stays on the active road. Information about the above object and the result of the query at both intersections of the active road are transmitted to the terminal 100.

The information provided by the server 200 should include the minimum necessary information that enables the terminal 100 to complete the k-nearest query results for any point on the active road. According to an exemplary embodiment of the present invention, the server 200 provides the terminal 100 with a preliminary query result assuming that a query is made at both intersections of an active road and location information about an object on an active road. However, the server 200 may further generate additional information in consideration of the computing power of the server 200 and the traffic capacity of the communication network, and provide the additional information to the terminal 100. An embodiment in which the server 200 not only calculates information requested by the terminal 100 right now but also generates additional information in advance through additional calculation is described with reference to FIG. 3.

3 is a diagram illustrating a configuration in which a moving path predictor is added in a server according to an embodiment of the present invention.

The movement path predictor 240 designates a request message for information about an object on an active road on which the terminal 100 received from the terminal 100 stays and a result when a query is made at both intersections of the active road. By monitoring the change trend of the intersection, the movement path of the terminal 100 is predicted.

That is, although the server may not monitor the current position of the terminal 100 completely, when the terminal 100 makes a request for a k-nearest query at every major intersection, the server 100 may predict the movement path of the terminal 100. Can be. In addition, according to another embodiment of the present invention, the server continuously monitors the current position of the terminal 100 and continuously calculates a preliminary query result in advance, thereby quickly responding to a request from the terminal 100. Preliminary query result information can be provided.

The k-nearest query result analysis method requests the server 200 for information about an object on the active road where the terminal 100 stays (S410). Thereafter, the server requests the result of the query at both intersections of the active road (S420). In this case, after requesting the result of the query at both intersections of the active road (S420), the server 100 may request the server 200 for information about the object on the active road where the terminal 100 stays (S410). have. In FIG. 4, step S410 is shown to be performed before step S420. However, since the two steps S410 and S420 are not processes having a mutual causal relationship, the two steps S410 and S420 may be independently performed. In some cases, the process may be performed in parallel, or the order of steps S410 and S420 may be reversed.

Subsequently, the server 200 receives information about an object on the active road and a result of a query at both intersections of the active road (S430), and receives information on an object on the active road and both intersections of the active road. Based on the result of the query, the result of the query at an arbitrary point on the active road is analyzed (S440).

5 is a flowchart illustrating an operation for requesting object information from a server when a client terminal enters an intersection of one of active roads according to an embodiment of the present invention.

When the terminal 100 enters an intersection of one of the active roads (S510), when the terminal 100 requests a server for a result of a query at both intersections of the active roads at which the terminal 100 stays, the intersection is S510. Information on an object on at least one road connected to the server 200 may be requested to the server 200 (S520). If the terminal 100 does not enter the intersection of either side of the active road (S510), the information about the object on the active road from the server 200 and the result when inquiring at both intersections of the active road Receive (S430).

At least one road connected to an intersection when the terminal 100 enters an intersection of one of the active roads (S610) when the server 100 requests a result of a query at both intersections of the active roads (S420). The terminal 100 requests the server for information on an object on the remaining road except for the previous active road where the terminal 100 was previously located (S620), and if the terminal 100 enters an intersection of any one of the active roads (S610). If not, the server 200 receives information about the object on the active road and a result when a query is made at both intersections of the active road (S430).

When the terminal 100 analyzes the result when the query is made at an arbitrary point on the active road (S440), considering the shortest path that can actually access any object (S441), The result of the query at any point is analyzed (S442). In this case, the closest distance may be calculated by comparing the shortest distance on the straight line with the shortest distance calculated using the traffic information and the road information received from the server 200.

8 is a flowchart illustrating a k-nearest preliminary query process performed in a server according to an embodiment of the present invention.

The terminal 100 receives information about an object on an active road on which the terminal 100 is staying and a request message for a result when a query is made at both intersections of the active road (S810), and an object on the road connected to both intersections of the active road. Using the information, the result of querying at both intersections of the active road is calculated (S820).

Thereafter, in response to the request message, the terminal 100 transmits the information about the object on the active road and the result of the query at both intersections of the active road to the terminal 100 (S830).

9 is a flowchart illustrating a pre-calculation of a query result even when a server does not receive a request message of a terminal according to another embodiment of the present invention.

When the server 200 does not receive the request message of the terminal 100 (S910), the query result is calculated in advance (S940) for the intersection around the active road of the terminal 100, and the request message is received ( In operation S 910, the result of the query at both intersections of the active roads is calculated using the object information on the roads connected to both intersections of the active roads of the terminal 100 (S920). In this case, the result may be calculated using the previously stored query result.

Thereafter, in response to the request message, information about the object on the active road and a result of a query at both intersections of the active road are transmitted to the terminal 100 (S930).

10 is a flowchart illustrating a precomputation of a query result by predicting a moving path of a terminal in a server according to another embodiment of the present invention.

When the request message is not received from the terminal 100 (S910), the change trend of the intersection crossed by the request message received from the terminal 100 is monitored to predict the moving path of the terminal (S950), and around the active road. The query result is calculated beforehand at the intersection of (S940).

When receiving the request message from the terminal 100 (S910), using the object information on the road connected to both intersections of the active road to calculate the result when the query at both intersections of the active road (S920), The resultant value can be used when predicting the movement path of the terminal by monitoring the change trend of the intersection designated by the request message received from the terminal 100 (S950).

Thereafter, in response to the request message, information about the object on the active road and a result when a query is made at both intersections of the active road are transmitted to the terminal 100.

When the terminal 1110 enters both intersections 1120 on the active road on which the terminal 1110 stays, the server 200 provides query results for both intersections 1120 and information on an arbitrary object 1130. Ask. In this case, when the terminal 1110 enters an intersection 1120 of any one of the active roads, the terminal 1110 is located on the other road except for the previous active road where the terminal 1110 was previously located. Information of the object 1130 may be requested to the server.

Subsequently, upon receiving the query result and the information on the arbitrary object 1130 from the server, the terminal 1110 considers the shortest path that can actually access the current road situation, traffic condition, etc. with respect to the arbitrary object 1130. Analyze the results of a query at any point on the active road. In other words, instead of simply searching for the nearest object based on a straight line distance or Euclidean distance between the point and the object that are the criteria of the query, the shortest path is considered considering the path that the terminal 1110 can actually access, such as the arrangement of the intersection and the road network. Compute the path. When the terminal 1110 is mounted in a vehicle, or when the owner of the terminal 1110 moves in a car, the accessible path may be set in consideration of the case where the owner of the terminal 1110 moves on foot. have. According to another exemplary embodiment, the server or the terminal 1110 calculates the shortest path based on the path of the vehicle based on the moving speed of the terminal 1110 or information registered in advance for the terminal 1110. You can also decide whether to compute based on the path. According to another exemplary embodiment, in addition to using information about a fixed road network, the server or terminal 1110 may calculate the shortest path by additionally considering information on an accident situation such as information on real-time traffic flow, accident, construction, etc. It may be. At this time, the main subject that calculates the shortest path is the terminal 1110, but the server also uses the information obtained about the terminal 1110 so that the terminal 1110 is suitable for calculating the shortest path. Additional route guidance information may be provided to the terminal 1110.

The terminal 1210 requests the server 1220 to request the result of the region nearest query at both the active road and the end points of the road where the terminal 1210 is staying (1230). Thereafter, the server 1220 searches for the result of the region nearest query and the objects on the active road at both ends of the active road to which the terminal 1210 belongs to the terminal 1210 according to a request of the terminal 1210, and transmits the result to the terminal 1210 (1240). In operation 1250, the terminal 1210 calculates a result of an arbitrary point on an active road by using the result value received from the server 1220. As such, the terminal 1210 shares the computational load concentrated on the server 1220 through the cooperative operation between the terminal 1210 and the server 1220, thereby reducing the load of the server 1220 and reducing the traffic of the network.

An analysis method of k-nearest query results and a distributed processing technique for continuous monitoring of query results according to an embodiment of the present invention are implemented in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. Can be. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, 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 not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents and equivalents of the claims, as well as the following claims, will fall within the scope of the present invention. .

The present invention relates to a distributed technique for continuous monitoring of k-nearest queries. More particularly, the present invention relates to a query result of a server that is requested for information about an object on an active road where a client terminal stays in a limited area of a road network. It relates to a method and an apparatus for analyzing.

The present invention is to develop a method of performing a part of the work performed by the server in the client terminal, away from the process in which the server processes not only the query processing but also the entire process including distance calculation for the terminal and any object. Through this distributed technique, the purpose is to reduce the computational cost of the server and to reduce the communication cost between the client and the server.

Claims

A client terminal for analyzing a k-nearest query result,

An object information request unit which transmits a message requesting a server for information about an object on an active road on which the terminal is staying and a result of a query at both intersections of the active road;

A query that analyzes the result when a query is made at any point on the active road based on the information about the object on the active road received from the server and the result of the query at both intersections of the active road A result calculator;

Client terminal comprising a.
The method of claim 1,

The object information requesting unit transmits the message to the server when the terminal enters an intersection of any one of the active roads.
The method of claim 1,

The object information requesting unit requests the server for information of an object on at least one road connected to the intersection when the terminal enters an intersection of any one of the active roads.
The method of claim 1,

When the terminal enters an intersection of any one of the active roads, the object information request unit includes information on an object on the other road except for the previous active road where the terminal was previously located among at least one road connected to the intersection. The client terminal requesting the server.
The method of claim 1,

The query result calculating unit analyzes a result when a query is made at an arbitrary point on the active road in consideration of the shortest path that is actually accessible to any object.
The method of claim 1,

The query result calculation unit

Client terminal for analyzing the results of the query at the current position of the terminal.
The method of claim 1,

The query result calculation unit

The client terminal designates the arbitrary point according to a user input, and analyzes the result when a query is made at the designated arbitrary point.
A server providing information for k-nearest query,

A request message receiving unit which receives a request message from the client terminal on the object on the active road on which the client terminal is staying and a request message on the result of querying at both intersections of the active road;

A query calculation unit that calculates a result when a query is made at both intersections of the active road using object information on the roads connected to both intersections of the active road; And

A transmission unit which transmits information about an object on an active road on which the client terminal is staying and a result when a query is made at both intersections of the active road in response to the request message to the client terminal;

Server comprising.
The method of claim 8,

The query operator is configured to pre-calculate the query result for the intersection around the active road before receiving the request message from the terminal.
The method of claim 8,

A movement path predicting unit configured to predict a movement path of the terminal by monitoring a change trend of an intersection designated by the request message received from the terminal;

More,

The query operation unit

And calculating a query result in advance for the selected intersection based on the predicted moving path.
In the k-nearest query result analysis method performed in the client terminal,

Requesting a server for information about an object on an active road on which the terminal is staying;

Requesting the server of the results of the query at both intersections of the active road; And

Receiving information about an object on the active road from the server and a result when a query is made at both intersections of the active road;

Analyzing the results of the query at any point on the active road based on the information about the object on the active road and the results of the query at both intersections of the active road;

K-nearest query results analysis method comprising a.
The method of claim 11,

Requesting the server for information of an object on at least one road connected to the intersection when the terminal enters an intersection of one of the active roads;

K-nearest query results analysis method further comprising.
The method of claim 11,

When the terminal enters an intersection of one of the active roads, the server requests information of an object on the other road except for the previous active road where the terminal was previously located among at least one road connected to the intersection. Doing;

K-nearest query results analysis method further comprising.
The method of claim 11,

Analyzing the results when a query is made at any point on the active road

A k-nearest query result analysis method which analyzes the result when a query is made at an arbitrary point on the active road considering the shortest path that is actually accessible to any object.
In the method for providing information for k-nearest query performed in the server,

Receiving a request message from a client terminal about information on an object on an active road on which the client terminal is staying and a result when a query is made at both intersections of the active road;

Calculating a result when a query is made at both intersections of the active road using object information on a road connected to both intersections of the active road; And

In response to the request message, transmitting information about an object on the active road and a result of a query at both intersections of the active road to the client terminal;

Information providing method for a k-nearest query comprising a.
The method of claim 15,

Computing the results of the query is

And a pre-computing query result for the intersection around the active road before receiving the request message from the terminal.
The method of claim 15,

Predicting a moving path of the terminal by monitoring a change trend of an intersection designated by the request message received from the terminal;

More,

Computing the results of the query is

And a pre-computing query result for a selected intersection based on the predicted moving path.
A computer-readable recording medium in which a program for executing the method of any one of claims 11 to 17 is recorded.