KR101997610B1 - Discovery Method in M2M System using Classification and Priority - Google Patents

Abstract

In order to reduce the burden on the system and provide quick search results in response to a discovery request generated in the M2M system, the present invention applies the classification and priorities of the device type and the installation area in consideration of the M2M characteristic and performs discovery ) ≪ / RTI > requests.

Description

[0001] The present invention relates to a discovery method using a classification and a priority of an M2M system,

The present invention relates to a discovery method in an M2M system, and more particularly, to a discovery request generated in an M2M system by applying classification and priority in consideration of M2M characteristics, And the like.

Object communication is variously called M2M (Machine to Machine communication), MTC (Machine type communication), IoT (Internet of Thing), Smart Device communication, or Machine oriented communication. Object communication refers to all communication methods in which communication is performed without a person intervening in the communication process. In this M2M system based on object communication, M2M devices and gateways are managed and controlled through the M2M platform on the network communicating with the M2M devices installed in the local network such as the home network or through the gateways interworking with them, The user terminal can provide the M2M service for various monitoring such as the operation state of the device on the local network and the environment monitoring.

In general, a discovery request in an M2M system is used by an issuer to perform a search for resources that match a particular filter condition under <sclBase>. The resource search procedure allows searching for resources existing in the Service Capability Layer (SCL), and filtering is performed on a subset of the attributes of the resources provided using the query string to reduce search results. The search results are returned with a list of resource URIs (Uniform Resource Identifiers).

1 is a flowchart illustrating a discovery method in a conventional M2M system. Applications of networks, devices, gateways, or issuers of SCLs can make discovery requests (001) to the Hosting SCL for resource discovery using the Retrieve method, where the issuer is a known URI Use <sclBase> / discovery for the request (001). The Hosting SCL verifies the validity of the request and generates a list of retrieved URIs corresponding to the resource (002). The Hosting SCL returns the successful search response to the issuer, which contains a list of retrieved URIs (003).

However, the Hosting SCL compares the searchStrings value in all scl resources registered under the <sclBase> resource for discovery requests and finds the corresponding resource. In this conventional technique, if there are many scl registered in <sclBase>, the number of searchStrings to be compared in each scl is increased in a large amount. According to the European Telecommunication Standards Institute (ETSI) standard document, at least 15 resources must be scanned in order to perform a discovery request on a single registered scl. For example, if 100 scl's are registered in <sclBase>, 1500 discovery operations will be required to perform a discovery operation. If N scl is registered then N * 15 search operation is needed for discovery once. As the number of SCLs registered in the Hosting SCL increases and the number of requests for discovery operations increases, so many operations are required and the load on the system increases. It is possible to cause other errors due to an increase in the system load, and there is a problem that costs are incurred to solve the problems.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a device search method and a device search method in order to reduce a load on a system and provide a quick search result for a discovery request generated in an M2M system, And a method of effectively performing a discovery request by classifying and classifying the type and the installation area and priorities.

A method for managing an M2M device interworking with a gateway through a platform on a network and an M2M system discovery method for providing an M2M service using the control of the M2M device and data, according to an aspect of the present invention, A search list for resources classified by the type of the device and an installation area in the platform and resources corresponding to the search list are managed in a database, and a device type of a priority resource group of a device designated as a search target, Managing search priority of each resource including search priority by region; And searching for resources in the database based on the search priority managed in the search list by referring to the search list upon receiving a discovery request from the platform.

And after the retrieving, reflecting the result of the retrieval to the retrieval priority of the retrieval list in the platform.

The method of claim 1, wherein the updating comprises: determining a cumulative number of searches for resources of the search result, a number of cumulative requestors, .

The priority resource group is updated according to a specific range of the cumulative search number of the search result resource, the total number of cumulative requestors, or the search request point from the current search result each time the search is performed according to the discovery request.

The searching step may include searching for a priority in the priority resource group if there is no device type or region information in the discovery request, And performing the search in order from the highest priority according to the priority order of the sub-regions.

The searching step may include searching for a priority in the priority resource group if there is information on the device type or the device type in the discovery request, And performing search in order from the highest priority according to the priority order of the regions.

Wherein the searching step performs search in the priority resource group with priority if there is information on the device type and region in the discovery request, And performing a search sequentially from the highest priority.

The priority of the corresponding local lower device resources may be determined based on the total cumulative number of retrievals, the total number of cumulative requestors, or the time point of the search request from the present.

Wherein the priority of the device type is determined in descending order of the device type sub-regions classified to belong to the priority resource group, and the priority of the device type sub- Resources can be ordered in many order.

In accordance with another aspect of the present invention, there is provided an M2M system for managing an M2M device linked to a gateway through a platform on a network and for providing an M2M service using the control and data of the M2M device, A database for managing a search list and corresponding resources for the resources classified according to installation regions; And a distributed discovery management apparatus for managing a search priority of each resource including a device type of a priority resource group of a device designated as a priority search target and a search priority for each region in the search list, And controls the database to sequentially search the resources based on the search priority managed in the search list by referring to the search list according to the discovery request.

Wherein the distributed discovery management apparatus comprises: a search result providing unit for providing a corresponding search result according to the search; A resource search count counter that counts the cumulative search count of resources of the search result; A search requester number counter for counting the number of cumulative requesters for the resource of the search result; A search request time counter for determining a search request time for the resource of the search result; A resource priority comparing unit for updating the priority resource group based on the cumulative search number, the cumulative number of requestors, or the search request time; And a search list relocation management unit for relocating the search priority of the search list according to the updated priority resource group.

According to the discovery method of the M2M system according to the present invention, the M2M device resource to be searched is classified according to the device type and the region, and compared with all the registered M2M device resources at the time of the discovery request, So that the number of operations is greatly reduced compared to the conventional technology. Discovery reduces the number of operations required to reduce system load and cost.

In addition, by applying a priority resource to a search list classified by type and region, search time can be shortened because a resource with a high probability is first searched for in a discovery request. In addition, It also provides an effect that allows other searchers to find preferred resources.

1 is a flowchart illustrating a discovery method in a conventional M2M system.
2 is a view for explaining an M2M service environment in an M2M system based on ETSI standards for application of a discovery method according to an embodiment of the present invention.
FIG. 3 is a diagram for explaining resources for controlling each of the M2M devices according to regions registered and classified according to the types of the M2M devices in the search list of the M2M platform according to an embodiment of the present invention.
4 is a block diagram illustrating a DDM unit of an M2M platform according to an embodiment of the present invention.
5 is an example of a graph for illustrating priority resource group designation in a DDM unit according to an embodiment of the present invention.
6 is a diagram for explaining a relocation of a search list 220 in a DDM unit according to an embodiment of the present invention.
FIG. 7 is a flowchart illustrating a process of performing a discovery request in the M2M platform according to an embodiment of the present invention.
FIG. 8 is a flowchart illustrating a process of performing a discovery request in a using M2M platform according to an embodiment of the present invention and an interlocking process of a DDM unit.
FIG. 9 is a diagram for explaining an example of processing in the M2M platform for a discovery request of a tourist in Jeju Island according to an embodiment of the present invention.
FIG. 10 is a diagram for explaining a load relationship usable for a search operation in the example of FIG. 9. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

2 is a view for explaining an M2M service environment in an M2M system based on ETSI standards for application of a discovery method according to an embodiment of the present invention.

First, referring to FIG. 2, a basic environment of the M2M system for applying the discovery method according to an embodiment of the present invention will be described.

The network domain of the M2M system includes an M2M platform (or a central server) 110 having a Network Service Capability Layer (NSCL). The M2M device domain includes a Device Service Capability Layer (DSCL) And a gateway 142 having a gateway service capability layer (GSCL) installed thereon. A gateway application (GA) for supporting the M2M service may be installed in the gateway 142, and a network application (NA) supporting the M2M service may be installed in the M2M platform 110. [ In addition, the M2M platform 110 may include a Network Telco Operator Exposure capability capability (NTOE), a Network Generic Communication capability (NGC), a Network Security capability (NSEC), a Network Communication Selection (NCS) NSCL functions for control and data collection of M2M device 141 and gateway 142 such as Network Remote Entity Management capability, Network Reachability, Addressing and Repository (NRAR) and Network Application Enablement (NAE) M2M Service Bootstrap Function), and MAS (M2M Authentication Server). In particular, according to the present invention, a unit 200 (distributed discovery management means) for a DDM (Distributed Discovery Management) function is configured in the NSCL function of the M2M platform 110 to provide a search list 220, Management, SCL priority analysis (210), and the result of the analyzed priority is reflected in the search list (220) again.

The M2M device 141 may include a gateway 142 and a local network (e.g., a wired network or a wireless local area network (Bluetooth, ZigBee, NFC, etc.), and may optionally include a CDMA / WCDMA, , Or a wired / wireless Internet).

The M2M device 141 may also be connected to the M2M platform 110 via network communications including core networks such as CDMA / WCDMA, mobile communication networks such as WiFi, or wired and wireless Internet such as WiBro, The M2M platform 110 monitors the M2M device 141 and the gateway 142 by using various data collected from the M2M device 141 and the gateway 142 to various user terminals including a mobile terminal such as another server or a smart phone Information and the like can be provided.

Each interface (ie, mIa (NA-NSCL interface)) with Service Capabilities (DSCL, GSCL, and DSCL), which is defined by the ETSI standard and is a set of service functions required to perform object communication, Utilizes resource information for mId (interface between platform (NCSL) and gateway (GSCL) / device (DSCL)), dIa (interface inside device (DA-DSCL) or interface between device (DA) and gateway (GSCL) , And resource information such as attribute information necessary for the service in each service function (DSCL, GSCL, DSCL).

Here, the M2M device (s) 141 on which the DSCL or the device application DA is mounted can be used for various purposes such as fire, intrusion, elderly and child (observer) observation, private security, Such as a camera, a motion detection sensor, a temperature sensor, a humidity sensor, a wind direction sensor, a pressure sensor, a gyro sensor, an acceleration sensor, and the like, A thermometer, a heart rate monitor, and the like, or various electronic devices for a home network, and various M2M devices for various M2M services can be installed as needed.

In the M2M system according to the present invention, the DDM unit 200 is used to classify and prioritize M2M characteristics to reduce the load on the system and to provide quick search results for discovery requests generated in the M2M system The algorithm for operating the system will be described in detail with reference to FIG. 3 to FIG.

The Hosting SCL (NSCL) of the M2M platform 110 constitutes a search list 220 classified so as to be classified according to the type of the corresponding M2M device and the installation location at the time of registration of the M2M device 141. [ 3, the category corresponding to the top of the search list 220 is the type of the M2M device 300, and the type of the installed area 310 classified by the type of each M2M device 141, Resources (SCL1 resource, SCL2 resource, SCL3 resource, ..) for control of each M2M device can be managed. The M2M service provider may distribute and operate the M2M device 141 nationwide and use the area 310 as a subclassification of the device type 300 in the search list 220. [

Various kinds of devices such as device names, models, and versions exist due to the characteristics of the M2M device 141, and by classifying and managing devices of the same type, it is not necessary to search for all kinds of devices when searching for a specific type of device resource. Also, since devices of the same kind are installed and located nationwide, regional classification is useful for searching device resources at specific locations.

In this manner, a search list 220 is constructed and managed so that a priority order for determining which items of the search list 220 to search first is applied. In order to determine the priorities in advance, the DDM unit 200, which is the distributed discovery management means of FIG. 2, is provided with a network application NA, a device application DA, an application GA of a gateway and SCLs DSCL, GSCL, The SCL priority analysis 210 is performed by referring to the information about the discovery request from the issuer of the mobile terminal 200 and the result value is applied to the search list 220, Allows the results to be reflected when performing a discovery request.

4 is a block diagram illustrating a DDM unit 200 of the M2M platform 110 according to an embodiment of the present invention.

Referring to FIG. 4, the DDM unit 200 according to an embodiment of the present invention includes a search result providing unit 400, a resource search number counter 410, a search requestor counter 420, 430, a resource priority comparison unit 440, and a search list relocation management unit 450.

The search result providing unit 400 is a module that allows the Hosting SCL (NSCL) of the M2M platform 110 to be downloaded from the issuer of each application (NA, DA, GA etc.) or each SCL (DSCL, GSCL, DSCL, (See FIG. 7) according to the SCL priority analysis 210 (refer to FIG. 7) by referring to the information about the discovery request of the SCL, (E.g., device type, region, resource name, resource URI, etc., as information on the M2M device resource) to the respective components as described above.

The resource search frequency counter 410 counts the number of cumulative searches for the resource of the search result as described above, that is, the number of requests for the discovery, and stores it in the database.

The search requester number counter 420 counts the number of different cumulative requesters for the resource of the search result and stores the counted number in the database.

The search request time counter 430 stores a search request point of the search result, i.e., a discovery request, in the database in order to determine from which point in time the search according to the relevant discovery request occurred.

The resource priority comparison unit 440 compares the values of the cumulative search count of the resource search times counter 410, the cumulative requestors of the search request number counter 420 and the search request time of the search request time counter 430 And updates the priority resource group 500 (see FIG. 5) that reflects information on the resources of the search result to the database.

The search list relocation management unit 450 refers to the priority resource group 500 (see FIG. 5) updated by the resource priority comparison unit 440 and searches for the resource in the search list 220 of the database Relocate (or redirect) the search priority.

FIG. 5 is an example of a graph for describing priority resource group designation in the DDM unit 200 according to an embodiment of the present invention.

The cumulative search count 510 of the resource search count counter 410, the cumulative number of requestors 520 of the search requestor counter 420 and the search request time 530 of the search request time counter 430 It can be managed in the form as shown in FIG.

5, the cumulative search count 510 of the resource search counter 410, the cumulative number of requestors 520 of the search requester counter 420, and the search request time 530 of the search request time counter 430 The priority comparison unit 440 may designate the group of the retrieved resources that satisfies the specific range condition for the priority resource group 500 as the priority resource group 500. [ For example, if a search request according to a discovery request that satisfies a latest search request time 530 that the cumulative total search count 510 is greater than or equal to 100, the total cumulative number of requestors 520 is greater than or equal to 100, And assign the group of resources to the priority resource group 500. When the resource priority comparison unit 440 designates the priority resource group 500, the search list relocation management unit 450 refers to the priority resource group 500 and searches for the type 300 of the M2M device and the region 310 (SCL1 resource, SCL2 resource, SCL3 resource, ...) for controlling each of the M2M devices to the search list 220 and manages the resources of the priority resource group 500 on the M2M platform The search priority may be updated every time the search is performed according to the discovery request so that the Hosting SCL (NSCL) of the search server 110 preferentially searches the search list 220 for the schedule display.

6 is a diagram for explaining a relocation of a search list 220 in the DDM unit 200 according to an embodiment of the present invention.

In FIG. 6, the resource 1 640, the resource 2 650, the resource 3 660, the resource 5 670, the resource 6 680, the resource 9 690, the resource 13 740, ) And the resource 17 (760) belong to the priority resource group 500. The list relocation management unit 450 relies on the type information 300 of the M2M device based on the number of resources belonging to the priority resource group 500, Regional (310) search priorities can be specified. For example, in a type of one M2M device, the priority of a region having a large number of resources belonging to the priority resource group 500 is set high, and the priority of a type of an M2M device having many regions having a particularly high priority You can specify a higher ranking.

In the example of FIG. 6, when it is assumed that the device type 1 600 is classified into the lower region 1 610, the region 2 620, and the region 3 630, the priority belonging to the region 1 610 There are three priority resources that are specifically high according to the ranking resource group 500, so that there are more than two other regions, so that region 1 610 becomes a high priority 1 and region 2 620 becomes a next higher number of highly specified priority resources , So it becomes the regional priority 2. And Region 3 (630) contains one highly-specified priority resource, which is the third priority in the region.

Assuming that a search list 220 is determined as shown in FIG. 6, when a discovery request is processed, a resource having a high search priority of the M2M device 300 and the region 310 is given priority . &Lt; / RTI &gt;

For example, when performing a search in the Hosting SCL (NSCL) of the M2M platform 110 for a discovery request, if there are items to be searched among the resources of the device type 1 600 and the area 1 610 The resource 1 640, the resource 2 650, and the resource 3 660 are preferentially searched. If only the device type 1 600 is specified in the discovery request and there is no specific area range to be searched, priority is given to the subordinate resources of the area 1 610, which is the first priority of the device type 1 600 . Similarly, if there is neither a device type nor an area in the information on the discovery request, the resource 1 640 and the resource 2 650 (640) are placed under the device 1 (600) ), And resource 3 (660).

As described above, according to the present invention, the priority to be designated based on the priority resource group 500 is applied to the search list 220, and the resources to be searched for in the discovery request are sorted from the resource with the highest probability first It is possible to expect an effect of searching quickly by searching. As described above, the method of selecting resources having such a priority is based on the total accumulated search count 510, the total number of cumulative requestors 520, and the latest search request time 530 from the current Priority resources may also be viewed as preferred resources, many of which are preferred. Therefore, there is also an effect of locating resources with high preference in resource search.

7 is a flowchart illustrating a process of performing a discovery request in the M2M platform 110 according to an embodiment of the present invention. FIG. 8 is a flowchart illustrating a process of performing a discovery request in the using M2M platform 110 according to an embodiment of the present invention and an interlocking process of the DDM unit 200. Referring to FIG.

First, when the Hosting SCL (NSCL) of the M2M platform 110 receives a discovery request from an issuer of each application (NA, DA, GA etc.) or each SCL (DSCL, GSCL, (S800 in FIG. 7, S885 in FIG. 8), the NSCL sends a request for discovery to the discovery request It is checked whether or not the included factor value (information such as the search target resource name) (information such as the type of device to be searched, area, etc.) may be valid (S810 in Fig. 7, S886 in Fig. 8).

The NSCL refers to the search list 220 managed in the database and searches through the priority analysis 210 for the search result, that is, the Uniform Resource Identifier (URI) of the corresponding resource (s) (S820, S830, S840, S860, S870, S870, and S887 in Fig. 8) to notify the DDM unit 200 to perform the relocation of the search list 220 (S850 of FIG. 8, S888 and S889 of FIG. 8), and also returns the search result to the issuer requested for discovery (S880 of FIG. 7, S890 of FIG.

More specifically, the NSCL checks whether information on a discovery request or information on a device type among the parameter values contained in the information is included, and determines whether the device type can be classified (S820 in FIG. 7 If it is not possible to classify the device types, the search results are searched in the database from the corresponding resources of the highest priority region according to the search priority as shown in FIG. 6, (S860).

If there is information on the device type in step S820, it is checked whether or not the information about the discovery request or the factor value included therein is included in the region, S830). If it is impossible to classify the region, the corresponding resources of the lower highest priority region of the corresponding device type according to the search priority as shown in FIG. 6 are first searched in the database, The resources are searched until a search result is obtained (S870).

If it is possible to classify the area in S830, it is first searched from the lower highest priority resources of the corresponding region in the device type, and then the local resources of the search order of the next ranking in the device type and region are searched (S840). Herein, the priority order of the lower M2M device resources in the area is the order in which the total number of cumulative searches 510 or the total number of cumulative requestors 520 is larger or the search request time 530 is the latest Can be determined. At this time, since the resources are searched according to the priority, the probability of finding the resource to be searched increases, and the number of operations required for searching is also reduced.

Then, the NSCL generates a search result, i.e., a URI (Uniform Resource Identifier) list of the corresponding resource (s), and notifies the DDM unit 200 of the search result. The DDM unit 200 analyzes the search result, The search list 220 relocation is performed and applied to the next discovery request (S850). The NSCL also returns the search result to the issuer that requested the discovery (S880).

With the application of the present invention as described above, it is possible to efficiently and quickly search and respond to a discovery request for each device type and region.

9 is a diagram for explaining an example of processing in the M2M platform 110 for a discovery request of a tourist in Jeju Island according to an embodiment of the present invention. FIG. 10 is a diagram for explaining a load relationship usable for a search operation in the example of FIG. 9. FIG.

For example, one hundred tourists (910) at Seogwipo City in Jeju Island can search restaurants kiosk resources when they search for Seogwipo restaurants for lunch using mobile terminals and other user terminals. Assuming that there are 10,000 M2M device resources 900 nationwide and there are 100 restaurant-related kiosk resources 940 in Seoguipo City, if you use the prior art technology to perform a discovery request, ETSI (European Telecommunication) According to the Standards Institute standards document, 15 million search keyword comparison operations (930) are required since at least 15 resources must be examined to perform a discovery request in a single registered scl.

However, when the search list 220 to which the present invention is applied has been applied, 100 hundred restaurant-related kiosk resources 940 related to the Seogwipo city are already classified into each device type and region Therefore, the search keyword comparison operation 1570 of 150,000 times is required under the same condition as described above. By rearranging the search list 220 of the priority resource as shown in FIG. 6, the probability of finding a desired search word in a search priority resource is increased, so that the number of comparison operations is reduced to 150,000 times. Also, since priority resource means high preference, it is possible to obtain kiosk resource information of a restaurant having a high preference in Jeju Island (for example, a kokoku, a black pork, a mackerel society, etc.) when searching for a kiosk resource of a restaurant.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

M2M platform 110,
M2M device 141,
The gateway 142,
NSCL (Network Service Capability Layer)
DSCL (Device Service Capability Layer)
GSCL (Gateway Service Capability Layer)

Claims (11)

A discovery method of an M2M system for managing an M2M device interworking with a gateway through a platform on a network and providing an M2M service using the control and data of the M2M device,
A search list and corresponding resources of resources classified by type of device and installation area in the platform are managed in a database, and a device type and region search of a priority resource group of a device designated as a priority search target in the search list Managing search priority of each resource including a priority; And
Upon receiving a discovery request from the platform, searching the resource in the database based on the search priority managed in the search list, referring to the search list
The method comprising the steps of: The method according to claim 1,
After the searching step,
Updating the search priority of the search list in the platform by reflecting the result of the search
Further comprising the steps of: 3. The method of claim 2,
Wherein the updating comprises:
Determining a cumulative number of searches for a resource of the search result, a number of cumulative requestors, or a point of time of a search request, storing the determined cumulative number of cumulative requestors in the database, and updating the priority resource group and rearranging the search priority of the search list
The method comprising the steps of: The method according to claim 1,
The priority resource group is updated according to a specific range of the cumulative search number of the search result resource, the total number of cumulative requestors, or a search request point from the current search result at the time of each search according to the discovery request Gt; M2M &lt; / RTI &gt; The method according to claim 1,
Wherein the searching comprises:
If there is no device type or region information in the discovery request, the search is performed with priority in the priority resource group, and a priority order of device types and a priority order of device type subareas In order from the lowest priority to the highest priority
The method comprising the steps of: The method according to claim 1,
Wherein the searching comprises:
If there is information on the device type or the device type in the request for the discovery in the discovery request, the search is performed with priority in the priority resource group, and in the priority order of the corresponding device type sub- Steps to search sequentially from the highest priority
The method comprising the steps of: The method according to claim 1,
Wherein the searching comprises:
And searching for a priority in the priority resource group if there is information on a device type and an area in the discovery request, Steps to Perform Search
The method comprising the steps of: 8. The method of claim 7,
Wherein the priorities of the local lower device resources are determined on the basis of a total cumulative search number, a total number of cumulative requestors, or a search request time from the present. The method according to claim 5 or 6,
Wherein the priority of the device type is determined in descending order of the device type sub-regions classified to belong to the priority resource group, and the priority of the device type sub- Characterized in that the resources are ordered in a number of order. 1. An M2M system for managing an M2M device interworking with a gateway through a platform on a network and providing an M2M service using the control and data of the M2M device,
The platform includes: a database for managing a search list and resources corresponding to the types of devices and installed resources; And
And a distributed discovery management apparatus for managing a search priority of each resource including a device type of a priority resource group of a device designated as a priority search target and a search priority for each region in the search list,
Wherein the distributed discovery management apparatus refers to the search list in response to a discovery request and controls the database to sequentially search resources based on a search priority managed in the search list. 11. The method of claim 10,
The distributed discovery management apparatus includes:
A search result providing unit for providing a corresponding search result according to the search;
A resource search count counter that counts the cumulative search count of resources of the search result;
A search requester number counter for counting the number of cumulative requesters for the resource of the search result;
A search request time counter for determining a search request time for the resource of the search result;
A resource priority comparing unit for updating the priority resource group based on the cumulative search number, the cumulative number of requestors, or the search request time; And
A search list relocation management unit for relocating the search priority of the search list according to the updated priority resource group,
Gt; M2M &lt; / RTI &gt;

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