JP2012029330A - Tracking area setting device and user device, and tracking area setting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize a tracking area.SOLUTION: A user device transmits a service request to a cell where the user device is present based on a paging channel, updates a location registration based on an identifier of a tracking area informed and notifies information indicating the cell where the user device is present immediately before the location registration when updating the location registration. The tracking area setting device includes means for separating a predetermined cell from tracking area to which the predetermined cell belongs if the predetermined cell has a frequency of generation of the service request equal to or more than a threshold based on the frequency of generation of the service request. Tracking area setting device selects, based on a frequency of generation of the location registration, a cell, of the separated predetermined cells, having the maximum frequency of generation of the location registration due to moving from an adjacent cell to the separated predetermined cell, and determines whether the separated predetermined cell and the selected cell are unified in an identical tracking area.

Description

  The present invention relates to an LTE (Long Term Evolution) system, and more particularly to a tracking area setting device, a user device, and a tracking area setting method.

  A communication method succeeding W-CDMA and HSDPA (generic name UMTS), that is, LTE (Long Term Evolution) has been studied by the UMTS standardization organization 3GPP. As for the uplink, SC-FDMA (Single-Carrier Frequency Multiple Access) has been studied (for example, see Non-Patent Document 1).

  In the mobile communication network, the position of the user device in standby (idle mode) is stored in the network in units of tracking areas. The tracking area corresponds to a location area (LA) or a routing area (RA) in UMTS, and is configured by one or a plurality of cells.

In each cell, the identifier of the tracking area to which the own cell belongs is broadcast. The user device in the idle mode registers the position with respect to the tracking area in which it is located. The user apparatus stores the identifier of the tracking area where the current location is registered, and receives the notified identifier of the tracking area as the cell moves, and checks whether the tracking area has changed. For example, when the user apparatus moves to the adjacent cell and the identifier of the tracking area broadcast therein is different from the identifier of the tracking area currently registered by the own user apparatus, the user apparatus accesses in the uplink and performs location registration. Update. This location registration update is referred to as a tracking area update (TAU). In order to perform the tracking area update, it is necessary for the user apparatus to access in the uplink, so if the frequency is high, the battery will be consumed even though it is on standby. In order to reduce the load of tracking area update, it is desirable to increase the tracking area.
When an incoming call occurs to a user apparatus, the mobile communication network performs a simultaneous call (paging) in all cells constituting the tracking area where the user apparatus is registered. When called by paging, the user equipment accesses the cell in which the user equipment is located (ie, sends a service request), and the call is established. Since paging is transmitted even in a cell where there is no user device to be called, if the number of cells to be paged is too large, downlink radio resources are wasted. In order to reduce the paging overhead, it is desirable to reduce the tracking area. Thus, there is a trade-off between the tracking area update processing load and the paging overhead, and it is necessary to design a tracking area that satisfies the optimum balance.

3GPP TR 25.814 (V7.0.0), "Physical Layer Aspects for Evolved UTRA," June 2006 3GPP R2-061929 June 2006

In a conventional system such as UMTS, when a new cell is introduced, the tracking area update frequency, paging load, and the like are estimated based on the population distribution of the introduced area, and the tracking area is designed. In particular, if the tracking area is not designed after accurately grasping the cells that are adjacent in radio propagation, a large amount of tracking area updates occur, which may impose system capacity. In order to accurately grasp the radio propagation of a new cell, for example, it is necessary to install a new base station, transmit a pilot signal, and circulate with a dedicated vehicle equipped with a measuring instrument to measure the reception quality of the pilot signal However, this requires a lot of work. Moreover, in actual design, it is necessary to design in consideration of places where tracking area updates can occur intensively, such as railways and highways, and complicated design is required.
In order to reduce such labor, in 3GPP, when newly installing a base station apparatus of the LTE system, the new base station apparatus and the network are connected with a cable, and the power is turned on. It has been proposed to perform automatic setting (see Non-Patent Document 2). In particular, in response to future communication demands, it is desirable to realize such an automatic setting function, assuming a situation in which a large number of small base station devices such as home use base stations are installed.

  However, this proposal is based on a concept, and specific configurations of the base station apparatus and the user apparatus are not proposed.

  Therefore, the present invention has been made to solve at least one of the problems described above, and an object of the present invention is to provide a tracking area setting device, a user device, and a tracking area setting method capable of automatically optimizing a tracking area. Is to provide.

This tracking area setting device
A tracking area is composed of one or more cells,
The paging channel is transmitted in all the cells that make up the tracking area where the target user equipment is located,
Based on the paging channel, the user equipment transmits a service request to a cell that is located,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user apparatus updates the location registration based on the notified tracking area identifier, and when updating the location registration, the user apparatus displays information indicating a cell that was in the area immediately before the location registration. Notify
Service request measuring means for measuring the frequency of occurrence of the service request;
Location registration measuring means for measuring the frequency of occurrence of location registration;
Based on the occurrence frequency of the service request, it is determined whether or not the predetermined cell has an occurrence frequency of the service request equal to or higher than a predetermined threshold. Tracking area determining means for dividing a predetermined cell from a tracking area to which the predetermined cell belongs;
With
The tracking area determining means is configured to perform location registration by moving from the adjacent cell to the divided predetermined cell among the cells adjacent to the divided predetermined cell based on the frequency of occurrence of the position registration. A cell having the highest occurrence frequency is selected, and it is determined whether or not the predetermined divided cell and the selected cell are merged into the same tracking area.

This tracking area setting device
A tracking area is composed of one or more cells,
The paging channel is transmitted in all the cells that make up the tracking area where the target user equipment is located,
Based on the paging channel, the user equipment transmits a service request to a cell that is located,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user apparatus updates the location registration based on the notified tracking area identifier, and when updating the location registration, the user apparatus displays information indicating a cell that was in the area immediately before the location registration. Notify
Service request measuring means for measuring the frequency of occurrence of the service request;
Location registration measuring means for measuring the frequency of occurrence of location registration;
Based on the occurrence frequency of the service request, it is determined whether or not the predetermined cell has an occurrence frequency of the service request equal to or higher than a predetermined threshold. Tracking area determining means for dividing a predetermined cell from a tracking area to which the predetermined cell belongs;
With
The tracking area determination unit is configured to perform location registration by moving from the divided predetermined cell to the adjacent cell among the cells adjacent to the divided predetermined cell based on the frequency of occurrence of the location registration. A cell having the highest occurrence frequency is selected, and it is determined whether or not the predetermined divided cell and the selected cell are merged into the same tracking area.

This tracking area setting device
A tracking area is composed of one or more cells,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user device updates the location registration based on the notified tracking area identifier,
Location registration measuring means for measuring the frequency of occurrence of location registration;
Tracking area determining means for merging a tracking area having a location registration occurrence frequency equal to or higher than a predetermined threshold with a tracking area to which a cell adjacent to the tracking area belongs based on the location registration occurrence frequency;
Is provided.

This user device
A user device that performs wireless communication with the above tracking area setting device,
Based on the identifier of the tracking area that has been broadcast, if the tracking area in the area changes, access in the uplink,
A cell identifier notification means for transmitting a tracking area update including information indicating a cell that was in the area immediately before the tracking area in which the area is located changes;
Is provided.

This tracking area setting method is
A tracking area is composed of one or more cells,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
A location registration update step in which the user device updates location registration based on the notified tracking area identifier;
A location registration measurement step in which the tracking area setting device measures the frequency of occurrence of location registration;
A tracking area merger in which the tracking area setting device merges a tracking area having a frequency of occurrence of position registration equal to or greater than a predetermined threshold with a tracking area to which a cell adjacent to the tracking area belongs based on the frequency of occurrence of the position registration. Step;
Have

  According to the embodiment of the present invention, it is possible to realize a tracking area setting device, a user device, and a tracking area setting method that can automatically optimize a tracking area.

It is explanatory drawing which shows an example of the mobile communication system with which the tracking area setting apparatus which concerns on one Example of this invention is applied. It is a partial block diagram which shows the tracking area setting apparatus which concerns on one Example of this invention. It is a table which shows a response | compatibility with the cell which comprises a tracking area, and the generation frequency of a service request. It is a table which shows a response | compatibility with the tracking area of a transfer destination, and the occurrence frequency of tracking area update. It is a flowchart which shows operation | movement of the tracking area setting apparatus which concerns on one Example of this invention. It is a partial block diagram which shows the user apparatus concerning one Example of this invention. It is a table which shows a response | compatibility with the cell of a transfer destination, the cell of a transfer source, and the occurrence frequency of tracking area update. It is a flowchart which shows operation | movement of the tracking area setting apparatus which concerns on one Example of this invention.

Next, the best mode for carrying out the present invention will be described based on the following embodiments with reference to the drawings.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

  A mobile communication system to which a tracking area setting apparatus according to an embodiment of the present invention is applied will be described with reference to FIG.

  The mobile communication system is a system to which, for example, Evolved UTRA and UTRAN (also known as Long Term Evolution, or Super 3G) is applied.

The mobile communication system includes a base station (eNB: eNode B) 200 _m (m is an integer of m> 1) and a user apparatus (UE: User Equipment) 50 _n (n is an integer of n> 0). . 1 shows, the base station _{200 1,} 200 _{2, 200 3,} 200 4, 200 _5, 200 6, 200 ₇ and 200 ₈ and user apparatus _{50 1,} 50 2, 50 ₃ and 50 ₄ are shown. The base station _{200 1,} 200 _{2, 200 3,} 200 4, 200 _5, 200 6, 200 ₇ and 200 ₈ are each cell ₂₀₂ 1 cells that _cover, 202 _{2, 202} 3, ₂₀₂ 4, 202 5, ₂₀₂ 6, Called 202 ₇ and 202 ₈ .

An access gateway device (aGW: access gateway) 300 is provided in the core network 500, for example. It may be provided in a network other than the core network. The access gateway device may be divided into logical entities of a control plane (C-plane) and a user plane (U-plane), and may be used as MME (Mobility Management Entity) / UPE (User Plane Entity). The core network 500 includes a home location register (HLR) 400. The home location register holds an identifier of an access gateway device that manages each user device 50 _n .

In this embodiment, as an example, the cells 202 ₁ , 202 ₂ and 202 ₃ constitute the tracking area 204 ₁ , the cells 202 ₄ , 202 ₆ and 202 ₇ constitute the tracking area 204 ₂ , and the cells 202 ₅ and 202 the ₈ tracking area 204 ₃ will be described a case constructed, but for cells belonging to the tracking area may be changed as appropriate.

When there is an incoming call to the user apparatus 50 _n , the access gateway 300 holds information on the tracking area registered by the user apparatus 50 _{n, and} thus knows which tracking area should be paged. For this reason, the access gateway 300 transmits paging to all the base stations constituting the tracking area. That is, on the network side, when the user apparatus 50 _n is in the idle mode, since there is no connection with the user apparatus 50 _n , it is not possible to specify a cell in the area. For this reason, the network transmits a paging channel in all cells belonging to the tracking area.

The base station 200 _m transmits a paging channel based on the paging transmitted from the access gateway 300. As a result, a paging channel is transmitted to the user apparatus 50 _n from the cell constituting the tracking area where the user apparatus 50 _n is located. For example, a cell constituting a tracking area where the user equipment 50 _n is located transmits a paging indicator channel, and then transmits a paging channel. The paging channel may include an international mobile subscriber identification ID // or a mobile subscriber identification ID (IMSI / TMSI: international mobile subscriber / temporary mobile subscriber identifier) and a cause ID indicating a communication type.

The user apparatus 50 _n that has received the paging channel determines whether or not its own global ID, that is, IMSI / TMSI, is included in the paging channel. Access is made through an accelerator channel (RACH: Randum Access Channel). Subsequent line setting is performed between the user equipment terminal 50 _n and the serving cell.

Specifically, the user apparatus 50 _n activates an uplink random access procedure, and transmits a random accelerator channel to the serving cell. Next, the serving cell transmits a response (RACH response) to the RACH to the user apparatus 50 _n . Based on the response to the RACH, the user apparatus 50 _n transmits a service request indicating that it is a transmission (response) for paging in the uplink.

The user device 50 _n that is in the idle state of the standby state performs tracking area update when it moves and the tracking area changes. The user device 50 _n in the idle state can receive the notified identifier of the tracking area and can grasp the tracking area to which the own user device 50 _n belongs. For example, when the user apparatus 50 _n moves to an adjacent cell and the identifier of the tracking area broadcast therein is different from the identifier of the tracking area in which the own user apparatus 50 _n is registered, the user apparatus 50 _n To access and update location registration. The user device 50 _n and the access gateway 300 store the identifier of the tracking area where the location registration has been performed.

  Next, a tracking area setting apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. The tracking area setting device 100 sets a tracking area.

  The tracking area setting device 100 according to the present embodiment is provided in the access gateway device 300, for example. The tracking area setting device 100 includes a network interface 102, a service request measurement unit 104, a tracking area update measurement unit 106, a tracking area determination unit 108, a control unit 110, and a storage unit 112. The storage unit 112 stores a tracking area-cell mapping table 114, a user equipment-tracking area mapping table 116, and a user equipment context 118.

The service request transmitted from the user device 50 _n is transmitted to the tracking area setting device 100 via the base station 200 _m . The service request received by the tracking area setting device 100 is input to the service request measurement unit 104 via the network interface 102. The service request measurement unit 104 measures the frequency of service request occurrence for each cell. For example, as shown in FIG. 3, the service request measurement unit 104 is a table (hereinafter referred to as an SR table) showing correspondence between a tracking area, cells constituting the tracking area, and service request occurrence frequency in the cell. ). The service request measurement unit 104 inputs the SR table to the tracking area determination unit 108 at a predetermined cycle. From the viewpoint of preventing frequent mergers and divisions of cells and / or tracking areas, which will be described later, this predetermined period is desirably a sufficiently long time. Alternatively, the operator may trigger as necessary.

In addition, the tracking area update transmitted from the user apparatus 50 _n is transmitted to the tracking area setting apparatus 100 via the base station 200 _m . The tracking area update received by the tracking area setting device 100 is input to the tracking area update measuring unit 106 via the network interface 102.

  The tracking area update measuring unit 104 measures the occurrence frequency of the tracking area update for each cell constituting the tracking area. For example, as shown in FIG. 4, the tracking area update measuring unit 104 indicates the correspondence between the tracking area at the transition destination, that is, the cells constituting the tracking area where the tracking area update has been performed, and the occurrence frequency of the tracking area update. A table (hereinafter referred to as a TAU table) is created. The tracking area update measurement unit 104 inputs the TAU table to the tracking area determination unit 108 at a predetermined cycle. From the viewpoint of preventing frequent mergers and divisions of cells and / or tracking areas, the predetermined period is desirably a sufficiently long time. Alternatively, the operator may trigger as necessary.

  The tracking area determination unit 108 optimizes the tracking area based on the input SR table and / or TAU table. For example, based on the input SR table, the tracking area determination unit 108 separates a cell whose service request occurrence frequency is equal to or higher than a predetermined threshold from the tracking area to which the cell currently belongs. Further, for example, based on the input TAU table, the tracking area determination unit 108 includes a cell in which the occurrence frequency of the tracking area update is equal to or higher than a predetermined threshold in the tracking area around the cell.

When paging is performed, the user apparatus 50 _n transmits a paging channel in a plurality of cells within a tracking area including the certain cell even though the user apparatus 50 _n is located in a certain cell. Since the paging channel transmitted outside the cell in which the user apparatus 50 _n is located is wasted, it is preferable that the number of cells constituting the tracking area is small in order to reduce the load on paging.

However, if the number of cells constituting the tracking area is small, the tracking area becomes small (narrow), and therefore the number of times that the user device 50 _n performs the tracking area update increases. In order to reduce the load on the tracking area update, it is preferable that the number of cells constituting the tracking area is large.

  Therefore, it is necessary to optimize the tracking area based on the load on paging and the load on tracking area update.

  Therefore, in the tracking area setting apparatus 100 according to the present embodiment, the tracking area determination unit 108 uses the tracking area-cell mapping table stored in the storage unit 112 based on the service request occurrence frequency and the tracking area update occurrence frequency. Referring to 114, the tracking area is optimized. From the viewpoint of preventing frequent mergers and divisions of cells and / or tracking areas, it is desirable to perform optimization with a sufficiently long period of time. Further, the switch may be turned on when the operator wants to perform optimization by using a switch for performing on / off setting.

  The tracking area determination unit 108 updates the tracking area-cell mapping table 114 and / or the user apparatus-tracking area mapping table 116 when a cell constituting the tracking area is changed as a result of optimization of the tracking area. .

  The tracking area-cell mapping table 114 is a table showing the correspondence between the tracking area and the cells constituting the tracking area. The user device-tracking area mapping table 116 is a table showing a correspondence between a user device and a tracking area where the user device is located. The user device context 118 stores the receiving user's context information, for example, the location (location registration information), the type of the user device, the information on available services, and the like.

  The control unit 110 performs line setting with the user device 50 based on the information stored in the storage unit 112. The network interface 102 is an interface with an upper node such as the HLR 400 and the base station 200.

  Next, an example of processing in the tracking area determination unit 108 in the tracking area setting apparatus 100 according to the present embodiment will be described with reference to FIG.

  The SR table described with reference to FIG. 3 and the TAU table described with reference to FIG. 4 are input to the tracking area determination unit 108 (step S502).

  Next, paying attention to a predetermined cell included in the SR table, it is determined whether or not the frequency of service requests corresponding to the predetermined cell is equal to or higher than a predetermined first threshold value (step S504).

  When the frequency of service requests corresponding to a predetermined cell is equal to or higher than a predetermined first threshold (step S504: YES), the predetermined cell is provisionally divided from the tracking area including (belonging to) the predetermined cell. (Step S506).

  Next, referring to the TAU table, an adjacent cell with the highest tracking area update frequency is selected from the cells adjacent to the temporarily divided predetermined cell (step S508).

  Next, the selected adjacent cell and the temporarily divided predetermined cell are temporarily merged (step S510).

  Next, it is determined whether or not the paging channel amount in the provisional merged tracking area including the selected adjacent cell and the provisionally divided predetermined cell is within a preset allowable range (step S512). . For example, referring to the SR table, the total value of the frequency of service requests in the provisional merged tracking area is calculated, and it is determined whether the total value is within a preset allowable range.

  When the total value is within the allowable range (step S512: YES), the selected adjacent cell is merged with the predetermined temporarily divided cell (step S514). On the other hand, if the total value is not within the allowable range (step S512: NO), the selected adjacent cell and the predetermined cell that has been provisionally divided are not merged (step S516). That is, the temporarily merged adjacent cells are separated from the temporarily divided predetermined cells.

  On the other hand, when the occurrence frequency of the service request corresponding to the predetermined cell is less than the predetermined first threshold (step S504: NO), the occurrence frequency of the service request corresponding to the predetermined cell is the predetermined second threshold. It is determined whether it is less than (step S518). Here, the second threshold is a value less than the first threshold.

  When the frequency of occurrence of the corresponding service request in the predetermined cell is less than the predetermined second threshold (step S518: YES), the TAU table is referred to, and the tracking area update of the cells adjacent to the predetermined cell is referred to. The neighboring cell with the highest occurrence frequency is selected (step S520).

  Next, the selected adjacent cell and the predetermined cell are provisionally merged (step S522).

  Next, it is determined whether or not the paging channel amount in the provisional merged tracking area including the selected adjacent cell and the predetermined cell is within a preset allowable range (step S524). For example, referring to the SR table, the total value of the frequency of service requests in the provisional merged tracking area is calculated, and it is determined whether the total value is within a preset allowable range.

  When the total value is within the allowable range (step S524: YES), the selected adjacent cell and the predetermined cell are merged (step S526). On the other hand, when the frequency of occurrence of the corresponding service request in the predetermined cell is not less than the predetermined second threshold (step S518: NO) and the total value is not within the allowable range (step S524: NO), the process returns to step S502.

  In this way, the tracking area can be optimized based on the frequency of service requests and the frequency of tracking area updates.

  Also, by optimizing the tracking area based on the service request occurrence frequency instead of the paging occurrence frequency, the tracking area can be optimized in units of cells.

  Next, a tracking area setting apparatus according to another embodiment of the present invention will be described.

  In the mobile communication system to which the tracking area setting device 100 according to the present invention is applied, the user device 50 that is in an active state during communication moves and accesses in the uplink when the tracking area in the area changes. Then, the location registration is updated. In this case, the identifier of the source cell is notified.

  In addition, when the user device 50 that is in the idle state of the standby state moves and changes the tracking area, it updates the tracking area and updates the location registration. In this case, the identifier of the source cell is notified. To do.

  As shown in FIG. 6, the user apparatus 50 according to the present embodiment includes an RF circuit 52 and a control plane processing unit 54 as a cell identifier notification unit.

  Since the user device 50 performs cell selection even in the idle state, the user device 50 knows the cell in which the user device 50 is located. The control plane processing unit 54 transmits the tracking area update including the identifier of the source cell, that is, the identifier of the cell that was in the area immediately before performing the tracking area update.

  The configuration of the tracking area setting apparatus according to the present embodiment is the same as the configuration described with reference to FIG.

The tracking area update including the source cell identifier transmitted from the user apparatus 50 _n is transmitted to the tracking area setting apparatus 100 via the base station 200 _m . The tracking area update received by the tracking area setting device 100 is input to the tracking area update measuring unit 106 via the network interface 102. The tracking area update measurement unit 104 measures the frequency of occurrence of tracking area updates by associating cells (migration destination cells) constituting the migration destination tracking area with the migration source cells.

  For example, as shown in FIG. 7, the tracking area update measurement unit 104 is in the service area immediately before moving to the cell that constitutes the tracking area of the transfer destination, that is, the cell in which the tracking area update has been performed. A TAU table indicating the correspondence between the cell (migration source cell) and the occurrence frequency of the tracking area update in the tracking area is created. In the TAU table shown in FIG. 7, cells that are not adjacent in the actual cell arrangement are also shown as the migration destination cells. However, based on the actual cell arrangement, the cells that are not adjacent become the migration destination cells. It may be omitted. In FIG. 7, in the actual cell arrangement, it is zero when a non-adjacent cell is the destination cell. The tracking area update measurement unit 104 inputs the TAU table to the tracking area determination unit 108 at a predetermined cycle. From the viewpoint of preventing frequent cell merging and division, it is desirable that this predetermined period is a sufficiently long time. Alternatively, the operator may trigger as necessary.

  Next, an example of processing in the tracking area determination unit 108 in the tracking area setting apparatus 100 according to the present embodiment will be described with reference to FIG.

  The SR table described with reference to FIG. 3 and the TAU table described with reference to FIG. 7 are input to the tracking area determination unit 108 (step S802).

  Next, paying attention to a predetermined cell included in the SR table, it is determined whether or not the frequency of service requests corresponding to the predetermined cell is equal to or higher than a predetermined first threshold value (step S804).

  If the occurrence frequency of the service request corresponding to the predetermined cell is equal to or higher than the predetermined first threshold (step S804: YES), the predetermined cell is provisionally divided from the tracking area including the predetermined cell (step S806). ).

  Next, referring to the TAU table, the frequency of occurrence of tracking area update due to movement from the adjacent cell to the provisionally divided predetermined cell among the cells adjacent to the provisionally divided predetermined cell (adjacent cell) Select the neighboring cell that maximizes. (Step S808).

  Next, the selected adjacent cell and the temporarily divided predetermined cell are temporarily merged (step S810).

  Next, it is determined whether or not the paging channel amount in the provisional merged tracking area composed of the predetermined temporarily divided cells and the selected adjacent cells is within a preset allowable range (step S812). ). For example, referring to the SR table, the total value of the frequency of service requests in the provisional merged tracking area is calculated, and it is determined whether the total value is within a preset allowable range.

  When the total value is within the allowable range (step S812: YES), the selected adjacent cell is merged with the temporarily divided predetermined cell (step S814). That is, a tracking area is configured by a predetermined cell that is provisionally divided from adjacent cells. On the other hand, when the total value is not within the allowable range (step S812: NO), the selected adjacent cell and the predetermined temporarily divided cell are not merged (step S816). That is, the adjacent cell is returned to the tracking area that belonged to before the temporary merger, and the tracking area is configured by the predetermined cells that are temporarily divided.

  On the other hand, when the occurrence frequency of the service request corresponding to the predetermined cell is less than the predetermined first threshold value (step S804: NO), the occurrence frequency of the service request corresponding to the predetermined cell is the predetermined second threshold value. It is determined whether it is less than (step S818). Here, the second threshold is a value less than the first threshold.

  When the occurrence frequency of the corresponding service request of the predetermined cell is less than the predetermined second threshold (step S818: YES), the TAU table is referred to, and the cell adjacent to the predetermined cell An adjacent cell that maximizes the frequency of occurrence of tracking area update due to the movement to the predetermined cell is selected (step S820).

  Next, the selected adjacent cell and the predetermined cell are provisionally merged (step S822).

  Next, it is determined whether or not the paging channel amount in the provisional merged tracking area constituted by the predetermined cell and the selected adjacent cell is within a preset allowable range (step S824). For example, referring to the SR table, the total value of the frequency of service requests in the provisional merged tracking area is calculated, and it is determined whether the total value is within a preset allowable range.

  When the total value is within the allowable range (step S824: YES), the selected neighboring cell and the predetermined cell are merged (step S826). On the other hand, when the occurrence frequency of the service request corresponding to the predetermined cell is not less than the predetermined second threshold (step S818: NO) and the total value is not within the allowable range (step S824: NO), the process returns to step S802.

  In this way, the tracking area can be optimized based on the frequency of service requests and the frequency of tracking area updates.

  In addition, the occurrence frequency of tracking area updates can be reduced.

  In this embodiment, in Steps S808 and S820, a cell adjacent to a predetermined cell that selects the adjacent cell that maximizes the occurrence frequency of tracking area update due to movement from the adjacent cell to the predetermined cell is selected. However, among the cells adjacent to the predetermined cell, an adjacent cell that maximizes the frequency of occurrence of the tracking area update due to movement from the predetermined cell to the adjacent cell may be selected.

  In addition, among the cells adjacent to the predetermined cell, the frequency of occurrence of tracking area update due to movement from the adjacent cell to the predetermined cell, and the frequency of occurrence of tracking area update due to movement from the predetermined cell to the adjacent cell. An adjacent cell that maximizes the sum of and may be selected.

  In the embodiment described above, the case where the tracking gateway setting device is provided in the access gateway device has been described. However, when the access gateway device is configured by MME / UPE, it may be provided in MME / UPE. Alternatively, when an OAM (Operation And Maintenance) server is provided in a mobile communication system to which the tracking area setting device is applied, the OAM server may be provided. By providing the OAM server, the tracking area can be optimized for cells covered by base stations under the control of a plurality of access gateway devices.

  The following items are further disclosed regarding the embodiment including the above examples.

(1) A tracking area is composed of one or more cells,
The paging channel is transmitted in all the cells that make up the tracking area where the target user equipment is located,
The user equipment transmits a service request to a cell that is located based on the paging channel,
Service request measuring means for measuring the frequency of occurrence of the service request;
Based on the occurrence frequency of the service request, it is determined whether or not the predetermined cell has an occurrence frequency of the service request equal to or higher than a predetermined threshold. Tracking area determining means for dividing a predetermined cell from a tracking area to which the predetermined cell belongs;
A tracking area setting device comprising:

(2) In the tracking area setting device according to (1):
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user device updates the location registration based on the notified tracking area identifier,
Location registration measuring means for measuring the frequency of occurrence of location registration;
With
The tracking area determining means selects a cell having the highest frequency of location registration among cells adjacent to the predetermined cell divided based on the frequency of occurrence of the location registration, and A tracking area setting device for determining whether or not to merge a cell and a selected cell into the same tracking area.

(3) In the tracking area setting device according to (1):
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user device updates the location registration based on the notified tracking area identifier,
When updating the location registration, the user device notifies the information indicating the cell that was located immediately before the location registration,
Location registration measuring means for measuring the frequency of occurrence of location registration;
With
The tracking area determining means is configured to perform location registration by moving from the adjacent cell to the divided predetermined cell among the cells adjacent to the divided predetermined cell based on the frequency of occurrence of the position registration. A tracking area setting apparatus, wherein a cell having the highest occurrence frequency is selected, and it is determined whether or not the predetermined divided cell and the selected cell are merged into the same tracking area.

(4) In the tracking area setting device according to (1):
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user device updates the location registration based on the notified tracking area identifier,
When updating the location registration, the user device notifies the information indicating the cell that was located immediately before the location registration,
Location registration measuring means for measuring the frequency of occurrence of location registration;
With
The tracking area determination unit is configured to perform location registration by moving from the divided predetermined cell to the adjacent cell among the cells adjacent to the divided predetermined cell based on the frequency of occurrence of the location registration. A tracking area setting apparatus, wherein a cell having the highest occurrence frequency is selected, and it is determined whether or not the predetermined divided cell and the selected cell are merged into the same tracking area.

(5) In the tracking area setting device according to any one of (2) to (4):
The tracking area determination means estimates a service request occurrence frequency in a tracking area constituted by the predetermined divided cells and the selected cells that have been temporarily merged, and the division based on the estimated value A tracking area setting device for determining whether or not to merge a predetermined cell and a selected cell.

(6) A tracking area is composed of one or more cells,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user device updates the location registration based on the notified tracking area identifier,
Location registration measuring means for measuring the frequency of occurrence of location registration;
Tracking area determining means for merging a tracking area having a location registration occurrence frequency equal to or higher than a predetermined threshold with a tracking area to which a cell adjacent to the tracking area belongs based on the location registration occurrence frequency;
A tracking area setting device comprising:

(7) A tracking area is composed of one or more cells,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
Based on the identifier of the tracking area that has been broadcast, if the tracking area in the area changes, access in the uplink,
A cell identifier notification means for transmitting a tracking area update including information indicating a cell that was in the area immediately before the tracking area in which the area is located changes;
A user apparatus comprising:

(8) A paging channel transmission step in which the base station transmits a paging channel in all the cells configured by one or a plurality of cells constituting the tracking area where the user apparatus to be received exists.
A service request transmission step in which a user apparatus transmits a service request to a cell in the area based on the paging channel;
A service request measuring step in which the tracking area setting device measures the frequency of occurrence of the service request;
A service request occurrence frequency determining step in which the tracking area setting device determines whether a predetermined cell has a service request occurrence frequency equal to or higher than a predetermined threshold based on the service request occurrence frequency;
A tracking area dividing step of dividing the predetermined cell from the tracking area to which the predetermined cell belongs when the tracking area setting device has a frequency of occurrence of service requests equal to or higher than a predetermined threshold;
A tracking area setting method characterized by comprising:

(9) A tracking area is composed of one or more cells,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
A location registration update step in which the user device updates location registration based on the notified tracking area identifier;
A location registration measurement step in which the tracking area setting device measures the frequency of occurrence of location registration;
A tracking area merger in which the tracking area setting device merges a tracking area having a frequency of occurrence of position registration equal to or greater than a predetermined threshold with a tracking area to which a cell adjacent to the tracking area belongs based on the frequency of occurrence of the position registration. Step;
A tracking area setting method characterized by comprising:

50, 50 ₁ , 50 ₂ , 50 ₃ , 50 ₄ User device 100 Tracking area setting device 102 Network interface 104 Service request measurement unit 106 Tracking area update measurement unit 108 Tracking area determination unit 110 Control unit 112 Storage unit 114 Tracking area-cell mapping table 116 the user equipment - tiger King area mapping table 118 the user device context 200, 200 _{1, 200 2,} 200 _{3, 200 4,} 200 5, 200 _6, 200 7, 200 ₈ base station 202, 202 _{1, 202} 2, 202 _{3, 202 4,} 202 _5, 202 _6, 202 7, 202 ₈ cells 204, 204 _{1, 204} 2, 204 ₃ tracking area 300 access gateway aGW: access Gateway)
400 Home Location Register (HLR)

Claims (6)

A tracking area is composed of one or more cells,
The paging channel is transmitted in all the cells that make up the tracking area where the target user equipment is located,
Based on the paging channel, the user equipment transmits a service request to a cell that is located,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user apparatus updates the location registration based on the notified tracking area identifier, and when updating the location registration, the user apparatus displays information indicating a cell that was in the area immediately before the location registration. Notify
Service request measuring means for measuring the frequency of occurrence of the service request;
Location registration measuring means for measuring the frequency of occurrence of location registration;
Based on the occurrence frequency of the service request, it is determined whether or not the predetermined cell has an occurrence frequency of the service request equal to or higher than a predetermined threshold. Tracking area determining means for dividing a predetermined cell from a tracking area to which the predetermined cell belongs;
With
The tracking area determining means is configured to perform location registration by moving from the adjacent cell to the divided predetermined cell among the cells adjacent to the divided predetermined cell based on the frequency of occurrence of the position registration. A tracking area setting apparatus, wherein a cell having the highest occurrence frequency is selected, and it is determined whether or not the predetermined divided cell and the selected cell are merged into the same tracking area. A tracking area is composed of one or more cells,
The paging channel is transmitted in all the cells that make up the tracking area where the target user equipment is located,
Based on the paging channel, the user equipment transmits a service request to a cell that is located,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user apparatus updates the location registration based on the notified tracking area identifier, and when updating the location registration, the user apparatus displays information indicating a cell that was in the area immediately before the location registration. Notify
Service request measuring means for measuring the frequency of occurrence of the service request;
Location registration measuring means for measuring the frequency of occurrence of location registration;
Based on the occurrence frequency of the service request, it is determined whether or not the predetermined cell has an occurrence frequency of the service request equal to or higher than a predetermined threshold. Tracking area determining means for dividing a predetermined cell from a tracking area to which the predetermined cell belongs;
With
The tracking area determination unit is configured to perform location registration by moving from the divided predetermined cell to the adjacent cell among the cells adjacent to the divided predetermined cell based on the frequency of occurrence of the location registration. A tracking area setting apparatus, wherein a cell having the highest occurrence frequency is selected, and it is determined whether or not the predetermined divided cell and the selected cell are merged into the same tracking area. In the tracking area setting device according to claim 1 or 2,
The tracking area determination means estimates a service request occurrence frequency in a tracking area constituted by the predetermined divided cells and the selected cells that have been temporarily merged, and the division based on the estimated value A tracking area setting device for determining whether or not to merge a predetermined cell and a selected cell. A tracking area is composed of one or more cells,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
The user device updates the location registration based on the notified tracking area identifier,
Location registration measuring means for measuring the frequency of occurrence of location registration;
Tracking area determining means for merging a tracking area having a location registration occurrence frequency equal to or higher than a predetermined threshold with a tracking area to which a cell adjacent to the tracking area belongs based on the location registration occurrence frequency;
A tracking area setting device comprising: A user device that performs wireless communication with the tracking area setting device according to any one of claims 1 to 4,
Based on the identifier of the tracking area that has been broadcast, if the tracking area in the area changes, access in the uplink,
A cell identifier notification means for transmitting a tracking area update including information indicating a cell that was in the area immediately before the tracking area in which the area is located changes;
A user apparatus comprising: A tracking area is composed of one or more cells,
In each tracking area, the identifier of the tracking area is broadcast from each cell,
A location registration update step in which the user device updates location registration based on the notified tracking area identifier;
A location registration measurement step in which the tracking area setting device measures the frequency of occurrence of location registration;
A tracking area merger in which the tracking area setting device merges a tracking area having a frequency of occurrence of position registration equal to or greater than a predetermined threshold with a tracking area to which a cell adjacent to the tracking area belongs based on the frequency of occurrence of the position registration. Step;
A tracking area setting method characterized by comprising:

Images