JP6145419B2 - Location management server, program and method for transmitting capture range list to mobile terminal - Google Patents

Description

  The present invention relates to a technique for location registration of a mobile terminal with respect to a core network.

  Conventionally, according to a cellular communication network such as LTE (Long Term Evolution), signaling processing such as location registration and paging is executed via a core network called EPC (Evolved Packet Core). In the EPC, a “location registration server” called MME (Mobility Management Entity) is installed to manage the location of the mobile terminal.

  FIG. 1 is a system configuration diagram showing location management of a mobile terminal in a location management server.

  According to the system of FIG. 1, a location management server (MME) 1 installed in a core network, a base station (eNB: evolved Node B) 2 installed in an access network, and a mobile terminal (UE: wireless) capable of wireless communication. User Equipment) 3.

The location management server 1 manages a set of one or more tracking areas (hereinafter referred to as “TA”) called pool areas. “TA” refers to a cell unit that includes one or more base stations and represents a location range of a mobile terminal in network management. According to FIG. 1, the location management servers MME # 1 and MME # 2 manage the pool areas # 1 and # 2 as follows.
Location management server MME # 1-> Pool area # 1-> TA # 1 (eNB # 1, eNB # 2)
TA # 2 (eNB # 3)
TA # 3 (eNB # 4)
Location management server MME # 2-> Pool area # 2-> TA # 4 (eNB # 5)

<Location registration sequence>
FIG. 2 is a sequence diagram of location registration in the prior art.

  The location management server sets the number of tracking areas (hereinafter referred to as “TA number”) to be transmitted to the mobile terminal to a predetermined value. According to FIG. 2, it is assumed that the location management servers MME # 1 and MME # 2 are set to the maximum “TA number = 2” in advance. That is, up to two TAs can be included in the TA list.

(S21) First, the mobile terminal 3 performs location registration with respect to the location management server 1. Specifically, the mobile terminal 3 sends a “location registration request” as a tracking area update (hereinafter referred to as “TAU”) to the location management server MME # 1 via the base station eNB # 1. Send signaling.
On the other hand, the location management server MME # 1 creates the TA list TAL # 1 in the pool area # 1 for the mobile terminal 3. Then, the location management server MME # 1 returns a “location registration response” as a tracking area update accept (hereinafter referred to as “TAUA”) including the TAL # 1 to the mobile terminal 3.
The mobile terminal 3 that has received the location registration response holds the TA list and recognizes the capture range.

(S22) It is assumed that the mobile terminal 3 has moved and connected to the base station eNB # 2. At this time, the base station eNB # 2 is included in TA # 1 of the TA list received by the mobile terminal 3 first. Therefore, the location of the mobile terminal 3 is managed by the location management server MME # 1 without executing the location registration sequence.

(S23) It is assumed that the mobile terminal 3 has moved and connected to the base station eNB # 3. At this time, the base station eNB # 3 is included in TA # 2 of the TA list previously received by the mobile terminal 3. Therefore, the location of the mobile terminal 3 is managed by the location management server MME # 1 without executing the location registration sequence.

(S24) It is assumed that the mobile terminal 3 has moved and connected to the base station eNB # 4. At this time, the base station eNB # 4 is not included in the TA list TAL # 1 previously received by the mobile terminal 3. That is, it means that the mobile terminal 3 has moved across the TA list. For this purpose, the mobile terminal 3 transmits a “location registration request” signaling as a TAU to the location management server MME # 1 via the base station eNB # 4.
On the other hand, the location management server MME # 1 creates a TA list TAL # 2 in the pool area # 1 for the mobile terminal 3. Then, the location management server MME # 1 returns a “location registration response” as TAUA including the TAL # 2 to the mobile terminal 3.
The mobile terminal 3 that has received the location registration response holds the TA list TAL # 2 and recognizes the capture range.

(S25) It is assumed that the mobile terminal 3 has moved and connected to the base station eNB # 5. At this time, the base station eNB # 5 is not included in the TA list TAL # 2 previously received by the mobile terminal 3. This means that the mobile terminal 3 has moved across the TA list. For this purpose, the mobile terminal 3 transmits a “location registration request” signaling as a TAU to the location management server MME # 2 via the base station eNB # 5.
On the other hand, the location management server MME # 2 creates the TA list TAL # 3 in the pool area # 2 for the mobile terminal 3. Then, the location management server MME # 2 returns a “location registration response” of TAUA including the TAL # 2 to the mobile terminal 3.
The mobile terminal 3 that has received the location registration response holds the TA list TAL # 3 and recognizes the capture range.

  According to FIG. 2, the mobile terminal 3 executes the location registration sequence when moving across the TA list or when a predetermined time has elapsed since the previous location registration. That is, the mobile terminal 3 does not have to execute the location registration sequence as long as it is communicating with the base station 2 included in the TA list within a predetermined time. As a result, the number of executions of the location registration sequence in the entire EPC can be kept as small as possible, and the load on the location management server can be suppressed.

<Paging sequence>
The location management server 1 manages the location of each mobile terminal 3 using the TA list. Here, according to the paging (calling) process, the location management server 1 confirms the TA list of the mobile terminal 3 when receiving an incoming call to the subordinate mobile terminal 3. Then, the location management server 1 performs paging up to three times for the called mobile terminal.
For the first time, the location management server 1 transmits a paging request to the tracking area TA for which the mobile terminal has last requested location registration.
If the location management server 1 fails to receive a paging response (Service Request) from the mobile terminal within a predetermined time, the location management server 1 considers paging failure. Second, the location management server 1 transmits a paging request to the entire tracking area TA of the mobile terminal.
The location management server 1 further regards the paging failure when it cannot receive a paging response from the mobile terminal within a predetermined time. Then, for the third time, the location management server 1 transmits a paging request to the entire tracking area TA of the mobile terminal.

WO2013012436A1

3GPP TS23.401 (V12.0.0), “General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access”, [online], [Search March 20, 2014], Internet <Http://www.etsi.org/deliver/etsi_ts/123400_123499/123401/08.14.00_60/ts_123401v081400p.pdf>

The location management server sets the number of TAs included in the TA list transmitted to the mobile terminal to a predetermined value. However, there are the following trade-offs depending on the set value of the TA number.
Large number of TAs-> (Advantage) Number of signaling in location registration processing decreases
(Disadvantage) Number of signaling in paging process increases TA number is small-> (Advantage) Number of signaling in paging process decreases
(Disadvantage) Number of signaling increases in location registration processing

  On the other hand, there is a technique in which the location management server creates a TA list for each mobile terminal according to the movement history (see, for example, Patent Document 1). However, according to this technique, a large number of location registrations are required to manage detailed locations for each mobile terminal, which increases the processing load on the location management server. There is also a problem that it is necessary to keep the movement history and a large amount of memory is required for the location management server.

  Therefore, according to the present invention, there is provided a location management server, a program, and a method capable of reducing the total number of paging processes while suppressing the number of location registration processes without increasing the processing load of the location management server. The purpose is to do.

According to the present invention, in a location management server that transmits a capture range list of communicable base stations to a mobile terminal,
For a plurality of base stations in its own management position range, base station storage means for storing the position of each base station with respect to the entire management position range;
The number of captured base stations that set the number of captured base stations to be included in the captured range list to be less than the number of mobile terminals that are routed through a base station that is not located in the fringe for mobile terminals that are located in the management position range fringe Setting means;
Each mobile terminal has acquisition range list creation means for creating an acquisition range list based on the number of acquisition base stations.

According to another embodiment of the location management server of the present invention,
The location management server is an MME (Mobility Management Entity) installed in EPC (Evolved Packet Core), and manages one or more base stations by dividing them into tracking areas (Tracking Area List).
The number of acquisition base stations is the number of tracking areas,
The capture range list is a tracking area list including one or more tracking areas,
The management position range is preferably a pool area.

According to another embodiment of the location management server of the present invention,
When the mobile terminal is connected to a base station not included in the tracking area list held by itself, the mobile terminal transmits a location registration request as a tracking area update (Tracking Area Update) to the location management server via the base station,
The location management server preferably returns a location registration response including the tracking area list to the mobile terminal.

According to another embodiment of the location management server of the present invention,
The location management server preferably transmits a paging request for a call connection request from another terminal using the tracking area list that has already been transmitted to the called mobile terminal.

According to another embodiment of the location management server of the present invention,
It is also preferable to further include a fringe base station determination means for determining a base station located in the fringe by Delaunay triangulation with all base station positions as vertices within its own management position range.

According to the present invention, a mobile terminal that communicates with the location management server described above,
Based on the number of captured base stations included in the captured range list received from the location management server via the base station, whether or not the currently communicating base station is in the fringe in the entire managed location range in the location management server It is characterized by determining.

According to the present invention, in a program for causing a mobile terminal to function a computer mounted on a location management server that transmits a capture range list of communicable base stations,
For a plurality of base stations in its own management position range, base station storage means for storing the position of each base station with respect to the entire management position range;
The number of captured base stations that set the number of captured base stations to be included in the captured range list to be less than the number of mobile terminals that are routed through a base station that is not located in the fringe for mobile terminals that are located in the management position range fringe Setting means;
A computer is caused to function as a capture range list creation unit that creates a capture range list based on the number of captured base stations for each mobile terminal.

According to the present invention, in a location registration processing method of a system having a mobile terminal, a base station, and a location management server that transmits a capture range list of base stations that can communicate with the mobile terminal,
The location management server has a base station storage unit that stores the location of each base station with respect to the entire management location range for a plurality of base stations in its management location range,
A first step in which a mobile terminal transmits a location registration request to a location management server via a base station;
If the location management server determines that the base station through which the location registration request has passed is located in the fringe of the management location range, the location management server sets the number of captured base stations to be included in the capture range list to be smaller than the base station not located in the fringe. Two steps,
A third step in which the location management server creates a capture range list based on the number of capture base stations for the mobile terminal;
The location management server includes a fourth step of returning a location registration response including the capture range list to the mobile terminal.

  According to the position management server, program, and method of the present invention, it is possible to reduce the total number of paging processes while suppressing the number of position registration processes without increasing the processing load of the position management server.

It is a system block diagram showing the position management of the mobile terminal in a position management server. It is a sequence diagram of location registration in the prior art. It is a function block diagram of the position management server in this invention. It is explanatory drawing showing the base station position in a pool area. It is explanatory drawing which derives | leads-out the base station located in a fringe using the Delaunay triangular decomposition method. It is a sequence diagram of location registration in the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The location management server of the present invention is specifically an MME installed in an EPC, and manages one or more base stations eNB by dividing them into TAs (tracking areas). Further, the location management server transmits a TA list (capture range list) including one or more TAs to the mobile terminal. The TA list includes as many TAs as the number of TAs (acquisition base stations) in the pool area (management location range).
Number of captured base stations: “Number of TAs”
Capture range list: “TA list”
Management position range: "Pool area"

  The location management server of the present invention changes the number of TAs according to the location of the base station that relayed the location registration sequence. It is determined whether or not the position of the base station is located at the fringe (edge) with respect to the entire pool area. Here, the number of TAs is set to be smaller in the base station located in the fringe than in the base station not located in the fringe. As a result, the number of location registration processes can be kept small, and the signaling transmitted toward useless TAs during the paging process can be reduced.

  FIG. 3 is a functional configuration diagram of the location management server in the present invention.

  According to FIG. 3, the location management server 1 includes a base station storage unit 10, a location registration request receiving unit 11, a captured base station number setting unit 12, a captured range list creating unit 13, and a location registration response transmitting unit 14. And a paging processing unit 15 and a fringe base station determination unit 16. These functional components are realized by executing a program that causes a computer mounted on the location management server to function. The processing flow of these functional components can also be understood as a location registration method.

[Base station storage unit 10]
The base station storage unit 10 stores, for a plurality of base stations in its own pool area, the position of each base station with respect to the entire pool area.

  FIG. 4 is an explanatory diagram showing base station positions in the pool area.

According to FIG. 4, the base stations in the pool area are classified as follows.
(1) A base station that is not located at a fringe has more adjacent base stations and more adjacent TAs in the entire periphery. In this case, a predetermined TA number (for example, TA number = 6) is set.
(2) The base station located in the fringe has fewer adjacent base stations and fewer adjacent TAs. In this case, a TA number (for example, TA number = 3) smaller than the predetermined TA number is set.

[Fringe base station determination unit 16]
The fringe base station determination unit 16 determines a base station located in the fringe by Delaunay triangulation using all base station positions as apexes within its own management position range.

  FIG. 5 is an explanatory diagram for deriving a base station located in a fringe using Delaunay triangulation.

The Delaunay triangulation method guarantees that no other vertex is included in the circumscribed circle connecting the three vertices.
According to FIG. 5A, the base station position is represented as a vertex.
According to FIG.5 (b), the circumcircle which connects 3 vertexes is drawn.
According to FIG. 5 (c), only circles having no other vertex included in the circumscribed circle are found.
According to FIG. 5D, a triangle is formed by connecting the vertices of the circumscribed circle finally found.
Finally, it is assumed that the base stations connected by a line are adjacent to each other. If at least one base station in a different pool area is adjacent, it can be determined that the base station is located in the fringe. Further, when all adjacent base stations are in the same pool area, it can be determined that they are not located in the fringe.

[Location registration request receiving unit 11]
The location registration request receiving unit 11 receives a location registration request from the mobile terminal 3 via the base station 2. The TAU included in the received location registration request and the passed base station ID are output to the captured base station number setting unit 12.
[Capture Base Station Number Setting Unit 12]
The acquisition base station number setting unit 12 uses the base station storage unit 10 (or the fringe base station determination unit 16) to determine whether the base station (ID) through which the location registration request has passed is located in the fringe of the pool area. (Depending on the result). Then, the base station located in the fringe is set to have a smaller number of TAs than the base station not located in the fringe. For example, set as follows.
A mobile terminal that has transmitted a location registration request via a base station not located in the fringe
<-Predetermined TA number (eg TA number = 6)
A mobile terminal that has transmitted a location registration request via a base station located in the fringe
<-TA number less than the default TA number (eg TA number = 3)
The set number of TAs and the position registration request are output to the capture range list creation unit 13.

[Capture Range List Creation Unit 13]
For each mobile terminal, a TA list is created based on the number of TAs. The created TA list is output to the location registration response transmission unit 14.

[Location registration response transmitter 14]
The location registration response transmission unit 14 returns a location registration response as TAUA including the created TA list to the mobile terminal 3.

[Paging processing unit 15]
When paging is required for the mobile terminal 3, the paging processing unit 15 determines an area to be paged using the TA list held for the mobile terminal. According to the present invention, since the number of TAs is small for a mobile terminal that passes through a base station located in a fringe, the paging area is inevitably narrowed down and the number of signaling is suppressed. As a result, the paging processing load of the location management server 1 is also reduced.

  FIG. 6 is a sequence diagram of location registration in the present invention.

(S61) When the mobile terminal 3 is connected to a base station not included in the TA list held by itself (moves across the TA list) (or when a predetermined time has elapsed since the previous location registration), the position as the TAU Send a registration request.
The base station 2 receives the location registration request from the mobile terminal 3, and adds the base station ID to the location registration request. The location registration request is further transferred to the location management server 1 (see the location registration request receiving unit 11 in FIG. 3).

(S62) The location management server 1 receives the location registration request, and acquires the base station ID included therein. Then, it is determined whether or not the base station position based on the base station ID is a fringe. Then, the number of TAs is set as follows (see the acquisition base station number setting unit 12 in FIG. 3).
A mobile terminal that has transmitted a location registration request via a base station not located in the fringe
<-Predetermined number of TAs A mobile terminal that has sent a location registration request via a base station located in the fringe
<-TA number less than the default TA number

(S63) The location management server 1 creates a TA list according to the set number of TAs (see the capture range list creation unit 13 in FIG. 3). Then, the terminal ID and the TA list are stored in association with each other.

(S64) The location management server 1 returns a location registration response as TAUA including the TA list to the mobile terminal that has transmitted the location registration request. As a result, the mobile terminal 3 receives the location registration response via the base station 2 and holds the TA list. When the mobile terminal 3 moves across the TA list, the mobile terminal 3 transmits a location registration request.

Also, based on the number of TAs included in the TA list received from the location management server 1, the mobile terminal 3 determines whether the currently communicating base station is in the fringe within the entire management location range in the location management server 1. It can be determined whether or not.
(1) When the number of TAs is a predetermined number, it means that the base station currently communicating is not in the fringe and the possibility of moving across the TA list is low thereafter.
(2) When the number of TAs is smaller than the predetermined number, it means that the currently communicating base station is in the fringe and is likely to move across the TA list thereafter.

(S65) The location management server 1 transmits a paging request for a call connection request from another terminal using the tracking area list that has already been transmitted to the called mobile terminal.

  As described above in detail, according to the position management server, program, and method of the present invention, the total number of paging processes can be suppressed without increasing the processing load of the position management server, while suppressing the number of position registration processes. Can be reduced. By reducing the number of signaling in the entire system, it is possible to reduce the cost required for infrastructure construction and the risk of failure due to overload.

  Various changes, modifications, and omissions of the above-described various embodiments of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

DESCRIPTION OF SYMBOLS 1 Location management server 10 Base station memory | storage part 11 Location registration request | requirement part 12 Captured base station number setting part 13 Captured range list creation part 14 Location registration response transmission part 15 Paging process part 16 Fringe base station determination part 2 Base station 3 Mobile terminal

Claims (8)

In a location management server that transmits a capture range list of communicable base stations to a mobile terminal,
For a plurality of base stations in its own management position range, base station storage means for storing the position of each base station with respect to the entire management position range;
A capture base that sets a smaller number of capture base stations to be included in the capture range list than a mobile terminal that travels through a base station that is not located in a fringe for a mobile terminal that travels through a base station located in the fringe of the management location range Station number setting means,
A location management server comprising capture range list creation means for creating a capture range list based on the number of capture base stations for each mobile terminal. The location management server is an MME (Mobility Management Entity) installed in an EPC (Evolved Packet Core), and manages one or more base stations by dividing them into tracking areas (Tracking Area List).
The number of captured base stations is the number of tracking areas,
The capture range list is a tracking area list (Tracking Area List) including one or more tracking areas,
The location management server according to claim 1, wherein the management location range is a pool area. When the mobile terminal is connected to a base station not included in the tracking area list held by itself, the mobile terminal transmits a location registration request as a tracking area update (Tracking Area Update) to the location management server via the base station,
The location management server according to claim 2, wherein the location management server returns a location registration response including a tracking area list to the mobile terminal. The location management server transmits a paging request for a call connection request from another terminal using the tracking area list that has already been transmitted to the called mobile terminal. 3. The location registration server according to 3.   The apparatus further comprises a fringe base station determining means for determining a base station located in the fringe by Delaunay triangulation with all base station positions as apexes within its own management position range. The location registration server according to any one of 1 to 4. A mobile terminal that communicates with the location management server according to any one of claims 1 to 5,
Based on the number of acquisition base stations included in the acquisition range list received from the location management server via the base station, the base station currently communicating is in the fringe in the entire management location range in the location management server. A mobile terminal characterized by determining whether or not. In a program for functioning a computer mounted on a location management server that transmits a capture range list of communicable base stations to a mobile terminal,
For a plurality of base stations in its own management position range, base station storage means for storing the position of each base station with respect to the entire management position range;
A capture base that sets a smaller number of capture base stations to be included in the capture range list than a mobile terminal that travels through a base station that is not located in a fringe for a mobile terminal that travels through a base station located in the fringe of the management location range Station number setting means,
A program for a location management server, which causes a computer to function as a capture range list creating means for creating a capture range list based on the number of capture base stations for each mobile terminal. In a location registration processing method of a system having a mobile terminal, a base station, and a location management server that transmits a capture range list of base stations that can communicate with the mobile terminal,
The location management server has a base station storage unit that stores the location of each base station with respect to the entire management location range for a plurality of base stations in its management location range,
A first step in which the mobile terminal transmits a location registration request to the location management server via a base station;
The location management server, when it is determined that the base station through which the location registration request has passed is located in a fringe of the management location range, the number of captured base stations included in the capture range list rather than a base station not located in the fringe A second step of setting the
A third step in which the location management server creates a capture range list based on the number of capture base stations for the mobile terminal;
A location registration processing method comprising: a fourth step in which the location management server returns a location registration response including the capture range list to the mobile terminal.

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