Wireless communication system, base station device, move control node, and method of wireless communication

The wireless communication system of the present invention includes a base station (10) and a mobility management node (20). The base station (10) sends at least one information from among location information of the base station (10) and information about the size of a cell of the base station (10), to the mobility management node (20). The mobility management node (20) receives at least one information from among the location information of the base station (10) and the information about the size of the cell of the base station, from the base station (10).

TECHNICAL FIELD

The present invention relates to a wireless communication system, a base station, a mobility management node, and a wireless communication method.

BACKGROUND ART

According to LTE (Long Term Evolution) that is being standardized in 3GPP (3rd Creation Partnership Projects) at present, there has been proposed a wireless communication system which includes EUTRAN (Evolved UMTS Terrestrial Radio Access Network, UMTS=Universal Mobile Telecommunication System) and EPC (Evolved Packet Core) that are configured as shown inFIG. 1(4.2.1 of Non-patent document 1, FIGS. 4.2.1-1 and 4.2.1-2 of Non-patent document 2). The above titles are not restrictive, but EUTRAN may be called “LTE”, EPC may be called SAE (System Architecture Evolution), and EUTRAN and EPC may collectively be called EPS (Evolved Packet System).

As shown inFIG. 1, the EUTRAN includes eNode B (evolved Node B)10as a base station. The EPC includes CN (Core Network) Nodes comprising MME (Mobility Management Entity)20as a mobility management node, S-GW (Serving Gateway)30as a gateway, P-GW (Packet Data Network Gateway)40as a higher-level gateway, and HSS (Home Subscriber Server)50. eNode10is connected to UE (User Equipment) as a wireless communication apparatus through a wireless interface.

MME20is a node having a mobility management (location registration) function for UE60, a handover control function, a selection function for S-GW30and P-GW40, a bearer management function, etc. (4.4.2 of Non-patent document 1). S-GW30is a node for transferring user-plane packet data between eNode B10and P-GW40. P-GW40is a node for transferring transmission packet data from its own network (Home PLMN, PLMN=Public Land Mobile Network) to an external network (Visit PLMN) and transferring reception packet data from an external network to its own network. HSS50is a server for saving user information that is used to authenticate UE60.

According to LTE, TAs (Tracking areas) are assigned to UE60as areas in which UE60is to be paged when an incoming call is received (5.2.3 of Non-patent document 1). Specifically, when UE60registers its location in eNode B10, TAs are assigned to UE60by MME20, and the list of assigned TAs is registered in UE60. If UE60detects when it has moved to a TA that is not included in the registered list, UE60registers its location again in eNode B10in order to update the TAs (5.3.3.1 of Non-patent document 1).

In a region where the paging traffic is high, the number of TAs that are assigned to UE60when UE60registers its location is reduced in order to reduce the number of areas in which UE60is to be paged. In order to reduce the number of times that UE60registers its location, on the other hand, the number of TAs assigned to UE60which is moving at a high speed is increased.

Consequently, there is a trade-off between the number of TAs for reducing the paging traffic and the number of TAs for reducing the number of times that UE60registers its location. It is thus necessary to optimize the number of TAs assigned to UE60in view of the trade-off.

A general process of assigning TAs to UE60will be described below.

It is assumed that from among the respective cells of a plurality of eNodes B10, cells C#1through C#23are arranged as shown inFIG. 2, and cells C#1through C#23belong to TA#1through TA#7as follows:

Generally, MME20assigns TAs to LIE60according to a rule that is manually established by the operator. According to the rule, a plurality of TAs are fixedly assigned to UE60.

Specifically, in the example shown inFIG. 2, the rule is such that when UE60registers its location in either one of eNodes B10of the cells belonging to TA#1, two TAs represented as TA#1and TA#4are fixedly assigned to UE60.

Even when UE60, which is moving at a high speed, registers its location in either one of eNodes B10of the cells belonging to TA#1, TA#1and TA#4are assigned to UE60.

If the cells belonging to TA#1and TA#4are of the type which covers a very small range (having a radius of several hundreds meters), for example, then even though MME20assigns TA#1and TA#4to UE60, since UE60travels through TA#1and TA#4and enters TA#5in several seconds, UE60needs to newly register its location.

The time which UE60takes to travel through TA#1and TA#4will be actually calculated as described below.

It is assumed that UE60registers its location in eNode B10of C#2belonging to TA#1, the cells belonging to TA#1and TA#4have a diameter of 500 m (meter), and UE60travels at a speed of 80 km (kilo meter)/h (hour).

Therefore, the time which UE60takes to travel through TA#1and TA#4is 113 seconds (≈2500 m/80 km/h). This numerical value indicates that UE60will do its location registration in about two minutes. Therefore, the number of times that UE60registers its location cannot be reduced.

Since the number of times that UE60registers its location cannot be reduced, an optimum number of TAs cannot be assigned to UE60.

According to the practice of fixedly assigning a plurality of TAs to UE60, a plurality of TAs are also assigned to UE60which mostly does not move in daytime. Consequently, since the paging traffic for paging UE60, when an incoming call is received, has to cover the plural TAs, the paging traffic cannot be reduced, resulting in a large burden imposed on the wireless communication system.

As described above, the practice of fixedly assigning a plurality of TAs to UE60is problematic in that an optimum number of TAs cannot be assigned to UE60.

Furthermore, in as much as the operator manually sets the rule for assigning TAs to UE60in MME20, the rule has to be re-established each time eNode B10is added or removed. This requires the operator to spend a lot of time and make a lot of effort, and hence results in an increase in OPEX (Operation and Expenditure).

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a wireless communication system, a base station, a mobility management node, and a wireless communication method which are capable of solving at least one of the above problems.

A wireless communication system according the present invention comprises a base station and a mobility management node, wherein

said base station sends at least one information from among location information of the base station and information about the size of a cell of the base station, to said mobility management node; and

said mobility management node receives at least one information from among the location information of the base station and the information about the size of the cell of the base station, from said base station.

A base station according to the present invention comprises a transmitter for sending at least one information from among location information of a base station and information about the size of a cell of the base station, to a mobility management node.

A first mobility management node according to the present invention comprises a receiver for receiving at least one information from among location information of a base station and information about the size of a cell of the base station, from said base station.

A second mobility management node according to the present invention comprises:

a receiver for receiving, from a base station, information about movement of a wireless communication apparatus which registers its location in said base station; and

a controller for assigning a tracking area based on information about a layout of said base station and the information about movement.

According to the present invention, a first wireless communication method to be carried out by a base station, comprises:

the transmission step of sending at least one information from among location information of the base station and information, about the size of a cell of the base station, to a mobility management node.

According to the present invention, a second wireless communication method to be carried out by a mobility management node comprises the reception step of receiving, from a base station, at least one information from among location information of the base station and information about the size of a cell of the base station.

According to the present invention, the base station is arranged to send at least one information from among the location information of the base station and the information about the size of the cell of the base station, to the mobility management node.

Therefore, since the mobility management node can recognize a layout of cells by receiving at least one information from among the location information of the base station and the information about the size of the cell thereof, the OPEX required by manual operation of the operator for assigning tracking areas can be reduced, and it is possible to assign an optimum number of tracking areas to the wireless communication apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the present invention will be described below with reference to the drawings.

In all exemplary embodiments to be described below, the overall configuration of a wireless communication system is identical to the overall configuration of the wireless communication system shown inFIG. 1.

As shown inFIG. 3, eNode B10according to the present exemplary embodiment includes transmitter11for transmitting location information of the cell of eNode B10and information about the size thereof to MME20.

MME20according to the present exemplary embodiment includes receiver21for receiving the location information of the cell of eNode B10and the information about the size thereof from eNode B10.

Operation of the present exemplary embodiment will be described below with reference toFIG. 4.

As shown inFIG. 4, in step201, transmitter11of eNode B10sends the location information of the cell of eNode B10and the information about the size thereof to MME20. The information sent to MME20is received by receiver21of MME20.

Since MME20can recognize the layout of cells by receiving the location information of the cell of eNode B10and the information about the size thereof, the OPEX required by manual operation of the operator for assigning TAs can be reduced, and it is possible to assign an optimum number of TAs to UE60.

As shown inFIG. 5, eNode B10according to the present exemplary embodiment is different from eNode B10according to the first exemplary embodiment shown inFIG. 3in that receiver12and controller13are added thereto.

Controller13includes information about eNode B10, described below, in a message.

(1) Location Information of the Cell of eNode B10:

For example, the location information of the cell is the information of latitude and longitude of the location of the cell of eNode B10(e.g., the central location of the cell or the central location of eNode B10), which is acquired by a location information measuring device on eNode B10using a GPS (Global Positioning System) or the like. The location information of the cell may be information required to calculate the location, which is acquired by eNode B10using the GPS or the like.

(2) Information About the Size of the Cell of eNode B10:

For example, the size of the cell may represent the diameter or radius of the cell (e.g., 500 m, 1 km, or 2 km). Alternatively, the size of the cell may represent a type indicative of the size of the cell (e.g., Macro, Micro, Pico, or Femto).

(3) TA to Which the Cell of eNode B10Belongs:

(4) The eNode B10Number or the Cell Number of eNode B10:

The information (2) through (4) is preset in eNode B10.

The transmitter11sends a message including information (1) through (4) with respect to eNode B10to MME20.

Receiver12receives a message including the information of TAs assigned to UE60which has registered its location in its own eNode B10, from MME20.

Messages are also sent to and received from UE60by transmitter11, receiver12, and controller13.

MME20according to the present exemplary embodiment is different from MME20according to the first exemplary embodiment shown inFIG. 3in that transmitter22and controller23are added thereto.

Receiver21receives the message including the information (1) through (4) with respect to eNode B10from eNode B10.

Controller23creates a map representative of the layout of cells based on the information (1) through (4) with respect to eNode B10.

Controller23dynamically assigns an optimum number of TAs to UE60which has registered its location in eNode B10, based on the moving speed and moving direction of UE60and the map, and includes the information of the assigned TAs in a message.

Transmitter22sends the message including the information of the TAs assigned to UE60which has registered its location in eNode B10, to eNode B10.

Messages are also sent to and received from S-GW30by transmitter22, receiver21, and controller23.

Operation of the present exemplary embodiment will be described below.

In order for the wireless communication system to provide communication services stably and optimally, it adds, removes, and redeploys eNode B10depending on the traffic volume in a certain region and the place such as between buildings where a wireless signal from existing eNode B10does not reach.

Operation at the time eNode B10is added will be described with reference toFIG. 6.

It is assumed that, as shown inFIG. 7, C#30belonging to TA#1is newly added to the cell layout shown inFIG. 2.

In step402, transmitter11of added eNode B10sends a setup message (S1setup message) including the information (1) through (4) with respect to eNode B10to MME20.

Then, in step403, controller23of MME20calculates the range of TA#3based on the location information of C#1through C#5, C#30belonging to TA#1, creates a new map as shown inFIG. 7, and stores the new map in a memory (not shown in any of the figures).

Thereafter, in step404, transmitter22of MME20sends a response message to the setup message (S1Setup Response message) to eNode B10.

Controller23of MME20judges eNode B10whose connection link to its own MME20has been cut off as being removed, deletes the cell of removed eNode B10from the map, creates a new map, and stores the new map in the memory (not shown in any of the figures).

[When the Range Covered by the Cell of eNode B10is Changed]

Operation at the time the range covered by the cell of eNode B10is changed will be described below with reference toFIG. 8.

As shown inFIG. 8, in step601, the range covered by the cell of eNode B10is changed because of a redeployment or configurational change (replacement of the antenna, a change in the antenna direction, etc.) of eNode B10.

In step602, transmitter11of eNode B10with the cell-covered range being changed sends a reconfiguration message (S1Reconfiguration message) including information (1) through (4) with respect to eNode B10to MME20.

Then, in step603, controller23of MME20calculates the range of the TA, to which the cell with the range covered thereby being changed belongs, creates a new map, and stores the new map in the memory (not shown in any of the figures).

Thereafter, in step604, transmitter22of MME20sends a response message (S1Reconfiguration Response message) to the reconfiguration to eNode B10.

[When the Location of UE60is Registered]

When the location of UE60is registered (TA Update), controller23of MME20assigns an optimum number of TAs to UE60based on the moving speed Sue and moving direction Dir of UE60.

(A) Calculation of the Moving Speed Sue of UE60:

For example, the moving speed Sue of UE60can be calculated from a change in the number of TAs assigned when the location of UE60is registered within a certain period. Specifically, if the number of TAs has increased, then the moving speed of UE60is judged as high. Conversely, if the number of TAs has decreased, then the moving speed of UE60is judged as low. Information of the moving speed of UE60may acquired by other methods. For example, MME20can receive the information of the moving speed which is recognized by UE60from UE60via eNode B10.

(B) Calculation of the Moving Direction Dir of UE60:

For example, the moving direction Dir of UE60can be calculated from the track of registered locations of UE60within a certain period. Information of the moving direction Dir of UE60may acquired by other methods. For example, MME20can receive the information of the moving direction which is recognized by UE60from UE60via eNode B10.

(C) Assignment of TAs to UE60:

When TAs are assigned to UE60, they are assigned such that it takes UE60six minutes or more, for example, to travel through all the assigned TAs. The time that UE60takes to travel through all the assigned TAs is not limited to six minutes, but may be determined appropriately depending on the design of the system.

SPECIFIC EXAMPLE 1

It is assumed that, as shown inFIG. 7, UE60registers its location in eNode B10of C#2belonging to TA#1, the cells belonging to TA#1and TA#4have a diameter of 2 km, UE60has a moving speed Sue of 80 km/h, and UE60has a moving direction Dir from TA#1to TA#4.

If two TA#1and TA#4are assigned to UE60, then the distance over which UE60travels through TA#1and TA#4is 10 km across five cells (C#2, C#3, C#5, C#12, C#13) (=2 km*5). Therefore, the time which UE60takes to travel through TA#1and TA#4is 7.5 minutes (≈10 km/80 km/h). Since it takes UE60six minutes or more to travel through TA#1and TA#4, two TA#1and TA#4are assigned to UE60.

SPECIFIC EXAMPLE 2

It is assumed that, as shown inFIG. 7, UE60registers its location in eNode B10of C#2belonging to TA#1, the cells belonging to TA#1and TA#4have a diameter of 1.5 km, UE60has a moving speed Sue of 80 km/h, and UE60has a moving direction Dir from TA#1to TA#4.

If two TA#1and TA#4are assigned to UE60, then the distance over which UE60travels through TA#1and TA#4is 7.5 km across five cells (C#2, C#3, C#5, C#12, C#13) (=1.5 km*5). Therefore, the time which UE60takes to travel through TA#1and TA#4is 5.6 minutes (≈7.5 km/80 km/h). It does not take UE60six minutes or more to travel through TA#1and TA#4.

If three TA#1, TA#4, and TA#5are assigned to UE60and the distance and the time are recalculated, then the time which UE60takes to travel through TA#1, TA#4, and TA#5is 6.8 minutes (≈9.0 km/80 km/h). Since it takes UE60six minutes or more to travel through TA#1, TA#4, and TA#5, three TA#1, TA#4, and TA#5are assigned to UE60.

SPECIFIC EXAMPLE 3

It is assumed that UE60registers its location in eNode B10of C#2belonging to TA#1, as is the case with the above examples, but UE60has a moving speed Sue of 0 km/h.

It may be considered that UE60is in a company or the like and mostly does not move in daytime. Therefore, only one TA#1, to which C#2of eNode B10, in which UE60has registered its location belongs, is assigned to UE60. As only one TA is assigned to UE60that mostly does not move in daytime, the paging traffic for paging UE60, when an incoming call is received, covers only TA#1, the paging traffic is reduced and no burden is imposed on the wireless communication system.

The above process of assigning TAs to UE60is described below.

As shown inFIG. 9, when UE60registers its location in eNode B10, controller23of MME20calculates a moving speed Sue of UE60in step701. If the moving speed Sue is 0 in step702, then controller23assigns one TA, to which the cell of eNode B10, in which UE60has registered its location, belongs to UE60in step703.

If the moving speed Sue is not 0 in step702, then controller23calculates a moving direction Dir of UE60in step704, and then calculates a range of present TA (TA to which the cell of eNode B10, in which UE60has registered its location, belongs) in step705.

In the above exemplary embodiment, the range of TA is calculated if the moving speed Sue is not 0. However, the range of TA may be calculated if the moving speed Sue is equal to or higher than a predetermined speed, not 0.

The range of TA is calculated as shown inFIG. 10.

As shown inFIG. 10, the controller23sets, as x, the number of cells, of the cells belonging to TA, that are arrayed along the moving direction Dir of UE60in step801.

Then, controller23sets, as n, a next cell number (a first cell number when control comes from step801) in step802, and then sets, as Dn, the diameter of cell n set in step802in step803. At this time, the diameter of the cell received as the information in above (2) from eNode B10is used as the diameter of cell n. If the information in above (2) received from eNode B10represents the radius or type of the cell, then the diameter of the cell is determined based on the received information.

Then, controller23sets the sum of present TAd (0 when control comes from step801) and Dn set in step803as TAd representative of the range covered by TA, in step804.

Then, controller23sets, as new x, the difference produced by subtracting 1 from the present x in step805. If x is 0 in step806, then controller23stores TAd set in step804in the memory (not shown in any of the figures) in step807.

If x is not 0 in step806, then control goes back to step802, and the same processing is repeated until x becomes 0.

Therefore, the range TAd covered by TA is expressed by the equation 1 below where n represents the cell number.

Referring back toFIG. 9, controller23sets, as TAd, the present range of TA calculated in step705, and also sets, as TAdm, an initial value 0 in step706. Controller23then sets the sum of TAd and TAdm set in step706as new TAd in step707.

Then, in step708, controller23determines travel time T which UE60takes to travel through TA by dividing TAd newly set in step707by moving speed Sue calculated in step701.

Therefore, travel time T of UE60is expressed by equation 2 below where m represents the TA number.

Then, if travel time T calculated in step708exceeds a predetermined time of X minutes (a time required for UE60to travel through all the assigned TAs) in step709, then controller23assigns the present TAs to UE60in step710.

If travel time T calculated in step708is equal to or shorter than the X minutes in step709, then controller23sets, as new TAdm, TAd(m+1) representing a range covered by next TA along the moving direction of UE60in step711. Then, in step712, controller23calculates TAdm newly set in step711. Control then goes back to step707, and the same processing is repeated until travel time T exceeds the X minutes.

In the present exemplary embodiment described above, the moving speed Sue and the moving direction Dir are used as the information with respect to the movement of UE60. However, either the moving speed Sue or the moving direction Dir may be used in the present invention. For example, if only the moving speed Sue is used, then TAs that are present around the location of UE60may be assigned. If only the moving direction Dir is used, then a given number TAs along that direction may be assigned.

According to the present exemplary embodiment, as described above, when eNode B10is added or when the range that is covered by the cell is changed, eNode B10sends a message including the location information of the cell of its own and the information about the size thereof to MME20.

Therefore, MME20can recognize the layout of cells based on the location information of the cell of eNode B10and the information about the size thereof, and hence can dynamically assign an optimum number of TAs to UE60, as is the case with the first exemplary embodiment.

Furthermore, MME20is also capable of assigning an optimum number of TAs, which make the number of location registrations of UE60and the number of paging events balanced, to UE60in view of the moving speed Sue and the moving direction Dir of UE60.

When eNode B10is removed, MME20can judge that eNode10is removed based on the cut-off of the connection link to eNode B10.

According to the present exemplary embodiment, since eNode B10sends the above information to MME20, the manual operation of the operator for assigning TAs can be reduced and hence the OPEX can be reduced.

According to the present exemplary embodiment, when UE60registers its location, since MME assigns TAs to the UE based on the information about the layout of eNodes B10and the information about the movement of the UE, optimum TAs can dynamically be assigned to the UE depending on the movement of the UE. The movement of the UE may be represented by the moving speed and the moving direction, for example.

eNode B10according to the present exemplary embodiment is identical in configuration to, but is different in operation from, eNode B10according to the second exemplary embodiment shown inFIG. 5.

According to the first exemplary embodiment, eNode B10sends information (1) through (4) with respect to eNode B10to MME20when eNode B10itself is added. According to the present exemplary embodiment, eNode B10sends the information when UE60attaches itself. Attaching of UE60means first access from UE60to eNode B10, e.g., first access after the power supply is turned on. Other details of operation of eNode B10are the same as with the second exemplary embodiment.

MME20according to the present exemplary embodiment is identical in configuration and operation to MME20according to second exemplary embodiment shown inFIG. 5.

Operation of the present exemplary embodiment will be described below with reference toFIG. 11.

As shown inFIG. 11, UE60sends a message (Attach Request message) requesting its attachment to eNode B10in step901.

In step902, transmitter11of eNode B10as an attachment destination sends a message (Initial UE Message) for starting an attach procedure, including information (1) through (4) with respect to eNode B10and information of the Attach Request message, to MME20.

Then, if an authentication device (not shown in any of the figures) of MME20successfully authenticates UE60using user information stored in HSS50in step903, then transmitter22of MME20sends a message (Create Default Bearer Request message) requesting the creation of a bearer to S-GW30in step904.

In step905, S-GW30sends the message (Create Default Bearer Request message) requesting the creation of a bearer to P-GW40. In steps906,907, P-GW40sends a response message (Create Default Bearer Response message) to the message requesting the creation of a bearer via S-GW30to MME20.

At this time, controller23of MME20performs a process of calculating a range of TAs, to which the cell of eNode B10as the attachment destination belongs, creating a new map, and storing the new map in the memory, and also a process of assigning TAs to UE60which has attached itself.

Then, in step908, transmitter22of MME20sends a message (Initial Context Setup Request message) including the information of TAs assigned to UE60and a message (Attach Accept message) accepting the attachment, to eNode B10. In step909, transmitter11of eNode B10sends a message (Radio Bearer Establishment Request message) including the information of TAs assigned to UE60and the message (Attach Accept message) accepting the attachment, to UE60.

Thereafter, in step910, UE60sends a message (Radio Bearer Establishment Response message) including a response message (Attach Complete message) to the message accepting the attachment, to eNode B10. Then, in step911, transmitter11of eNode B10sends a message (Initial Context Setup Response message) including the response message (Attach Complete message) to the message accepting the attachment, to MME20.

According to the present exemplary embodiment, as described above, when UE60attaches itself, eNode B10sends information (1) through (4) with respect to eNode B10to MME20. Therefore, the latest information about eNode B10can be indicated to MME20. Other advantages are the same as those of the second exemplary embodiment.

eNode B10according to the present exemplary embodiment is identical in configuration to, but is different in operation from, eNode B10according to the second exemplary embodiment shown inFIG. 5.

According to the first embodiment, eNode B10sends information (1) through (4) with respect to eNode B10to M ME20when eNode B10itself is added. According to the present exemplary embodiment, eNode B10sends the information when UE60registers its location. Other details of the operation of eNode B10are the same as with the second exemplary embodiment.

MME20according to the present exemplary embodiment is identical in configuration and operation to MME20according to second exemplary embodiment shown inFIG. 5.

Operation of the present exemplary embodiment will be described below with reference toFIG. 12.

InFIG. 12, existing MME20and S-GW30are referred to as Old MME20-O and Old S-GW30-O, respectively, MME20which eNode B10has newly selected based on the information included in a location registration request message (TAU Request message) from UE60is referred to as New MME20-N, and S-GW30which New MME20-N has newly selected based on the information included in the TAU Request message is referred to as New S-GW30-N.

As shown inFIG. 12, UE60sends a TAU Request message for location registration to eNode B10in step1001.

In step1002, transmitter11of eNode B10as a location registration destination sends a message (Initial UE Message) for starting a TA Update procedure, including information (1) through (4) with respect to eNode B10and information of the TAU Request message, to New MME20-N.

In step1003, transmitter22of New MME20-N sends a message (Context Request message) requesting context information of UE60to Old MME20-O. In step1004, transmitter22of Old MME20-O sends a response message (Context Response message) to the message requesting context information of UE60to New MME20-N.

If the authentication device (not shown in any of the figures) of MME20successfully authenticates UE60using user information stored in HSS50in step1005, then transmitter22of new MME20-N sends a message indicating that the context of UE60is validated for New MME20-N and invalidated for Old MME20-O to Old MME20-O in step1006, and sends a message (Create Default Bearer Request message) requesting the creation of a bearer to New S-GW30-N in step1007.

In step1008, New S-GW30-N sends a request message (Update Bearer Request message) for changing a data transfer route from Old S-6W30-O to New S-GW30-N to P-GW40. In step1009, P-GW40sends a message (Update Bearer Response message) in response to the request message for changing the data transfer route to New S-GW30-N. In step1010, New S-GW30-N sends a response message (Create Bearer Response message) to the message for requesting the creation of a bearer to New MME20-N. In step1011, a process of releasing the bearer with respect to Old S-GW-30-O is carried out.

At this time, controller23of New MME20-N performs a process of calculating a range of TAs, to which the cell of eNode B10as the location registration destination belongs, creating a new map, a process of storing the new map in the memory, and also a process of assigning TAs to UE60which has registered its location.

In step1012, transmitter22of new MME20-N sends a message (Initial Context Setup Request message) including the information of TAs assigned to UE60and a message (TAU Accept message) accepting the location registration, to eNode B10. In step1013, transmitter11of eNode B10sends a message (Radio Bearer Establishment Request message) including the information of TAs assigned to UE60and the message accepting the location registration, to UE60.

Thereafter, in step1014, UE60sends a message (Radio Bearer Establishment Response message) including a response message (TAU Complete message) to the message accepting the location registration, to eNode B10. Then, in step1015, transmitter11of eNode B10sends a message (Initial Context Setup Response message) including the response message (TAU Complete message) to the message accepting the location registration, to MME20.

According to the present exemplary embodiment, as described above, when UE60registers its location, eNode B10sends information (1) through (4) with respect to eNode B10to MME20. Therefore, the latest information about eNode B10can be indicated to MME20. Other advantages are the same as those of the second exemplary embodiment.

The present invention has been described above in reference to the exemplary embodiments. However, the present invention is not limited to the above exemplary embodiments. Rather, various changes that can be understood by those skilled in the art within the scope of the invention may be made to the arrangements and details of the present invention.

For example, in the above exemplary embodiments, the LTE wireless communication system has been illustrated. However, the present invention is not limited to the LTE wireless communication system, but is also applicable to other wireless communication systems having mobility management nodes, a base station, and a wireless communication apparatus.

Furthermore, the above exemplary embodiments explain the wireless communication system wherein the mobility management nodes and the gateway are separate from each other. However, the present invention is also applicable to wireless communication systems wherein the mobility management nodes and the gateway are integral with each other.

The present application claims priority bas'ed on Japanese patent application No. 2008-021304 filed on Jan. 31, 2008, and incorporates herein the entire disclosure thereof by reference.