KR101580250B1 - .A communication system for access control during active handover toward a CSG cell and a method thereof - Google Patents

Abstract

The present invention relates to a wireless communication system supporting an LTE CSG base station. The present invention provides a communication system and a handover method for controlling a handover (HO) of a terminal to a CSG base station.

CSG (Closed Subscriber Group), Active handover, access control

Description

[0001] The present invention relates to a system and method for controlling access to a CSG base station during handover,

The present invention relates to a wireless communication system for handover and a method thereof, and more particularly, to a communication system and a handover method for controlling handover of a terminal when the terminal performs handover to a CSG base station.

A wireless communication network is based on a cellular system, and a wireless communication network in which macro and closed subscriber group cells (CSG cells) of such a cellular system are mixed will be described. A CSG cell or a femtocell is a cell that can cover a very small range in a cellular system, and a base station for managing such a CSG cell is called a CSG base station (or femto base station). Meanwhile, in the 3GPP LTE (Long Term Evolution), an evolved NodeB (eNB) and a home evolved NodeB (eNB) have been defined. The eNB is a macro base station that controls a general macro cell and the home eNB is an example of a CSG base station that controls a CSG cell.

1 is a diagram for explaining a configuration of a wireless communication network in which macro cells and CSG cells are mixed.

1, a wireless communication network according to an exemplary embodiment of the present invention includes a core network including an MME 105 and an evolved NodeB (eNB) 102 connected to the MME 105 A closed subscriber group (CSN) base station (HeNB) 103, a macro base station (eNB) 102, and a CSG base station (HeNB) 104 connected to the MME 105 through a gateway (HeNB GW) (Hereinafter referred to as "UE") 101 that wirelessly connects to a base station 103 via a network. At this time, the HeNB GW 104 among the network elements may not be installed.

The CSG cell broadcasts its CSG ID (CSG Identity) to the SIB (System Information Block). The UE has the CSG ID information of the CSG cell to which the UE can access, as the UE Allowed CSG list. When the UE reads the SIB of the CSG cell, it can determine whether or not the CSG cell can be accessed. The core network comprising the MME 105 also has this Access Allowed List (CSG list).

2 is a diagram showing a handover method from a macro base station to a macro base station.

Referring to FIG. 2, in step 206, the UE 201 detects a signal of the target cell 205 and reports the measurement to the serving cell 202. In step 207, the serving base station 202 analyzes the received measurement report to determine who is the target cell of the terminal, and based on the tracking area ID (TAI) of the target cell 205, the used frequency band, The MME 203 transmits a handover request message to the MME 203 in step 208. In step 208, The source MME 203 of the serving base station 202 transmits a handover request message to the target MME 204 connected to the target base station 205 in step 209 if necessary, A handover request message is transmitted to the target base station 205. However, if the source MME 203 is in charge of the target base station 205, it is not necessary to re-request the handover to the separate target MME 204, which will be applied equally hereinafter.

The target BS 205 transmits an Ack indicating that the target MME 204 can receive a handover to the target MME 204 in step 211. The target MME 204 performs handover to the source MME 203 in step 212 I can. The source MME 203 instructs the serving base station 202 to perform handover to the serving base station 202 in step 213 and the serving base station 202 instructs the mobile station 201 to perform handover to the target cell 205 in step 214. [

Thereafter, the MS 201 performs handover to the target cell 205 in step 215, and the target BS 205 informs the target MME 204 of the completion of the HO handover in step 216. The target MME 204 notifies the source MME 203 of the completion of the HO handover in step 217 and the source MME 203 transmits the ack information in step 218. In step 219, The serving base station 202 notifies the source MME 203 of the terminal information in step 220 and the resource used by the terminal.

However, when applying the above procedure to the active handover of a terminal from a macro base station to another CSG base station, there is no way to determine whether or not the terminal performing the handover can access the target CSG base station. Therefore, in order to solve the problem, the present invention proposes an access control method which allows the core network to examine whether or not the terminal can access the CSG base station and receive service when the active terminal moves to the CSG base station.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a wireless communication network that allows an active terminal to access a CSG base station, And a system therefor.

In a wireless communication network in which a macro base station and a CSG (Closed Subscriber Group) base station are mixed, a system for measuring report of a wireless communication network according to an exemplary embodiment of the present invention includes a serving BS, A serving base station for transmitting a CSG ID of the target CSG cell to the target MME after the handover of the UE is performed, and a handover control unit for performing handover based on the CSG ID reported by the target base station, The MME includes a MME for continuously performing or stopping a handover by confirming that the UE having performed the handover is a UE capable of receiving service in the target CSG cell.

Also, a method of controlling handover access control of a wireless communication system in which a macro base station and a CSG base station are mixed according to an exemplary embodiment of the present invention is characterized in that when a handover of the terminal is required, the MME of the serving base station transmits a handover request message Transmitting a CSG ID of a target cell connected to the target MME to the target MME, and transmitting the CSG ID of the target cell connected to the target MME to the target MME; Confirming whether the CSG ID of the target cell is included in the access allowance list of the UE; and if the CSG ID of the target cell is included in the UE allowed access list, And releasing the terminal information and the resource used by the terminal through the serving base station.

If the CSG ID of the target cell is not included in the access permission list of the UE, the target MME informs the target CSG base station and the source MME of the handover failure, and the target BS releases the RRC connection with the UE The method comprising the steps of:

A method for controlling handover access control of a wireless communication system in which a macro base station and a CSG base station are mixed according to an embodiment of the present invention includes the steps of a handover request of a serving base station to a target base station, Performing a handover between the target BS and the target BS, transmitting the CSG ID to the target CSG base station by the MME, and checking whether the CSG ID of the target cell is included in the access- If the CSG ID of the target cell is included in the UE allowed access list, the MME detects that the handover of the UE has been completed normally, and releases the UE information and resources used by the UE through the serving BS .

According to the present invention, when the active terminal performs handover to the CSG base station, it can efficiently control whether or not the terminal can access the CSG base station to be serviced in the core network to control handover of the terminal.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, only parts necessary for understanding the operation according to the present invention will be described, and the description of other parts will be omitted so as not to obscure the gist of the present invention.

The wireless communication network according to the embodiment of the present invention assumes a cellular system in which macro cells and CSG cells are mixed. In the following description, only the embodiment in which the macro base station is used as the serving base station will be described, but the present invention also includes the case where the serving base station is the CSG base station. In the present invention, when there is no great confusion, the base station and the cell are used in parallel with each other.

A first embodiment of the present invention relates to a procedure in which a mobile station attempts handover through a MME to a CSG cell granted by a macro base station and handover is successful.

The serving base station requests handover without determining whether the target CSG base station can be connected when the handover of the terminal is required, and the source MME transmits a handover request message and a terminal access permission list to the target side. Upon handover, the target CSG base station transmits the CSG ID of the cell accessed by the terminal to the target MME when notifying the target MME of the handover completion of the terminal. Then, the target MME confirms whether the target base station is included in the access allowed list (UE Allowed CSG List) received from the source MME upon the handover request, the CSG ID of the target cell to which the UE handover. At this time, if the CSG ID of the target cell is included in the access permission list of the UE, the target MME informs the source MME that the handover of the UE has been normally completed (Forward Relocation Complete) Releases resources used by the terminal.

A second embodiment of the present invention relates to a procedure when a handover is unsuccessful when a mobile station attempts a handover through a MME to a CSG cell not allowed in a macro base station.

The serving base station requests handover without determining whether the target CSG base station can be connected when the handover of the terminal is required, and the source MME transmits a handover request message and a terminal access permission list to the target side. Upon handover, the target CSG base station transmits the CSG ID of the cell accessed by the terminal to the target MME when notifying the target MME of the handover completion of the terminal. Then, the target MME confirms whether the target base station is included in the access allowed list (UE Allowed CSG List) received from the source MME upon the handover request, the CSG ID of the target cell to which the UE handover. At this time, if the CSG ID is not included in the access permission list of the UE, the target MME informs the source MME that the handover of the UE is denied and transmits a UE connection release command to the target CSG base station. Then, the target CSG base station blocks use of the CSG base station of the mobile station, and reports the result to the target MME. The source MME instructs the serving base station to erase all the UE related information, and the serving base station retrieves the terminal information and the resources used by the UE.

A third embodiment of the present invention relates to a procedure when a handover is successful by attempting a handover through a direct connection (i.e., an X2 interface) to a CSG cell allowed by a macro base station.

The serving base station requests the handover to the target cell and the target cell approves the handover request without determining whether the target CSG base station can be connected. Thereafter, the target BS performs a handover procedure between the MS and the target BS, and the target BS transmits the CSG ID of the CSG cell connected to the MS to the MME. Then, the MME confirms whether the target BS includes the CSG ID of the target cell handed over by the UE to the UE Allowed CSG List. If the CSG ID of the target cell is included in the access permission list of the UE, the MME informs the target cell and the serving BS of the target cell, and blocks the access of the UE in the target cell. In the serving BS, .

In a wireless communication network in which a macro base station and a CSG (Closed Subscriber Group) base station are mixed, a system for measuring and reporting a wireless communication network according to the first to third embodiments of the present invention includes a handover A serving BS for transmitting a CSG ID of the target CSG cell to the target MME after performing the handover of the MS, a target BS for transmitting the CSG ID of the target CSG cell to the target MME, And an MME for performing or stopping the handover by confirming that the terminal performing the handover based on the CSG ID reported by the base station is a terminal capable of receiving service in the target CSG cell.

The mobility control method according to the first to third embodiments of the present invention will be described. The system for measuring report of a wireless communication network according to an embodiment of the present invention can use a wireless communication network in which a macro base station and a CSG (Closed Subscriber Group) base station are mixed, and a configuration of a wireless communication network having the above- And can be configured as shown in FIG.

First Embodiment

3 is a diagram illustrating a case where a mobile station attempts handover to a CSG cell granted by a macro base station via the MME and handover is successful.

Referring to FIG. 3, the UE 301 detects a signal of the target cell 305 in step 306 and transmits a measurement report to the serving BS 302. Then, the serving base station 302 determines handover of the terminal through the measurement report transmitted from the terminal 301. At this time, the serving BS 302 transmits a handover request message to the source MME 303 in step 308 without determining whether the MS 301 can access the target CSG base station 305 or not. If necessary, the source MME 303 transmits a handover request message and a UE allowed CSG list to the target MME 304 connected to the target CSG base station 305 in step 309, The MS 304 transmits a Handover Request message to the target CSG serving station 305 in step 310. As described above, the serving BS 302 requests handover without determining whether the target CSG base station 305 can be connected when the MS needs a handover, and the source MME 303 transmits a handover request message And transmits the access permission list of the terminal.

In step 311, the target base station 305 transmits a handover request acknowledgment message to the target MME 304 indicating that the target MME 304 can receive the HO. The target MME 304 transmits a handover request acknowledgment (Forward Relocation Response). The source MME 303 transmits a handover command to the serving base station 302 in step 313 and the serving base station 302 transmits a handover command to the target mobile station 301 in step 314, command transmission).

In step 315, the MS 301 performs a handover with the target CSG cell 305. At this time, the target CSG base station 305 recognizes that the handover of the UE has been performed by receiving the handover confirm message (Handover Confirm) transmitted in step 315, and performs HO handover to the target MME 304 in step 316 And notifies the handover notify with the CSG ID of the cell connected to the terminal. In step 317, the target MME 304 controls access based on the access permission list of the UE (Access Control Based on UE Allowed CSG List). That is, when the target BS 305 informs the MS 300 of the handover of the MS in step 316, the target MME 304 transmits the CSG ID received in step 309 to the UE allowed CSG list Check if it is included. If the CSG ID transmitted in step 315 is included in the access control list received in step 309, the target MME 304 informs the source MME 303 that the handover of the terminal is normally completed Relocation Complete. Then, the source MME 303 responds to the target MME 304 (Forward Relocation Complete Acknowledge) in step 319, and commands the serving base station 302 to erase all the UE related information in step 320. In step 321, the serving base station 302 recovers the UE information and the resource used by the UE, and informs the source MME 303 of the result.

Second Embodiment

4 is a diagram illustrating a case where a handover is unsuccessful when a mobile station attempts handover to a CSG cell not allowed in a macro base station via the MME.

4, the UE 401 detects a signal of the target cell 405 in step 406 and performs a measurement report on the serving cell 402. In step 407, the serving BS 402, which receives the measurement report, The handover of the terminal is determined. At this time, the serving BS 402 transmits a handover request message to the MME 403 in step 408 without determining whether the MS 401 can access the target CSG base station 405 or not. In step 409, the source MME 403 transmits a handover request message and a UE allowed CSG list to the target MME 404 connected to the target CSG base station 405, if necessary. In step 410, the target MME 404 transmits a handover request message to the target CSG base station 405.

In step 411, the target base station 405 transmits a handover request acknowledgment message to the target MME 404. In step 413, the target MME 404 informs the source MME 403 of the handover to the source MME 403. In step 413, the source MME 403 instructs the serving base station 402 to perform handover of the mobile station, The MS 402 instructs the MS 401 to perform handover to the target BS in step 414.

Then, the terminal 401 performs handover to the target CSG cell 405. At this time, the target CSG base station 405 informs the target MME 404 in step 416 that the HO execution of the terminal is completed and the CSG ID of the cell to which the terminal is connected. In step 417, the target MME 404 determines whether the received CSG ID is included in the access permission list. That is, the target MME 404 determines whether the CSG ID of step 415 is included in the access permission list of the terminal received in step 409.

Here, the operations of steps 406 to 417 of FIG. 4 may be performed in the same manner as the operations of steps 306 to 317 of FIG.

If it is determined in step 417 that the CSG ID in step 415 is not included in the access permission list of the UE, the target MME 404 determines in step 418 that the handover of the UE is denied to the source MME 403 (Forward Relocation Failure), and transmits a UE Context Release Command to the target CSG base station 405 in step 419. In step 420, the target CSG base station 405 transmits a message (UE RRC Release message) for releasing the service of the UE 401 to block the use of the CSG base station of the UE in step 420. In step 421, UE Context Release Complete message) to the target MME 404. In step 419, the source MME 403 transmits a Forward Relocation Failure Ack message to the target MME 404 in step 419. In step 422, the source MME 403 transmits a Forward Relocation Failure Ack message to the serving base station 402 Command. In step 423, the serving base station 402 recovers the terminal information and the resources used by the terminal and reports it to the source MME 403.

FIG. 5 is a detailed diagram illustrating the operation of the target MME in FIGS. 3 and 4. FIG.

Referring to FIG. 5, in step 501, when the CSG base station reports a handover completion report of the UE and the CSG ID of the CSG cell connected to the UE, the target MME 404 transmits the CSG cell to the CSG cell It is determined whether or not the terminal is connectable. That is, the target MME checks whether the CSG ID of the target CSG cell is included in the access permission list of the terminal transmitted from the source MME. If the target CSG ID is included in the access permission list, the target MME proceeds to step 505, CSG base station access, and if the target CSG ID is not included in the access permission list, the mobile terminal proceeds to step 507 and refuses to access the CSG base station.

Third Embodiment

6 is a diagram illustrating a case where a handover succeeds when a mobile station attempts a handover through a direct connection (i.e., an X2 interface) to a CSG cell allowed in a macro base station.

Referring to FIG. 6, in step 605, the UE 601 detects a signal of the target cell 603 and transmits a measurement report to the serving cell 602. In step 606, the serving BS 602 determines the handover of the MS through the measurement report. In step 607, the serving BS 602 transmits a handover request message to the target CSG cell 603 without determining whether the target CSG cell 603 is reachable or not. Then, in step 608, the target CSG cell 603 informs the serving base station 602 that handover can be performed. In step 609, the serving base station 602 instructs the terminal 601 to perform handover to the target cell.

In step 610, the UE 601 performs handover to the target CSG cell 603 and notifies the target CSG base station 603 of the result (Handover Confirm). At this time, the target CSG base station 603 notifies the MME 604 of the completion of the handover of the terminal and informs the MME 604 of the CSG ID of the target cell connected to the terminal in step 611. [ The MME 604 then checks in step 612 whether the CSG ID received is included in the UE allowed CSG List. If the CSG ID received in step 611 is included in the access permission list of the UE, the MME 604 notifies the target CSG BS 604 of the completion of the HO handover of the UE in step 613, And instructs the base station 602 to recover the terminal information of the serving base station 602 and the resources used by the terminal. Then, the serving BS 602 recovers the UE information and user resources of the UE, and informs the MME 604 of UE Context Release Complete.

The embodiments of the present invention disclosed in the present specification and drawings are merely illustrative of specific embodiments of the present invention and are not intended to limit the scope of the present invention in order to facilitate understanding of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

1 is a view for explaining a configuration of a wireless communication network in which macro cells and CSG cells are mixed;

2 is a diagram showing a handover method from a macro base station to a macro base station

3 is a diagram illustrating a case where a mobile station attempts handover to a CSG cell granted by a macro base station via the MME and handover is successful

4 is a diagram illustrating a case where a handover is unsuccessful when the UE attempts handover through the MME to a CSG cell not allowed in the macro base station

FIG. 5 is a diagram showing in detail the operation of the target MME in FIGS. 3 and 4

6 is a diagram illustrating a case where a handover is successful by attempting a handover through a direct connection to a CSG cell allowed by a macro base station

Claims (10)

A method for controlling access of a target mobility management entity (MME) in a wireless communication system, Receiving a UE Allowed CSG List of the UE from a mobility management entity (MME) connected to the serving BS when the UE is handed over; Receiving a closed subscriber group (CSG) ID from a closed subscriber group (CSG) base station after the handover of the UE is performed; And Comparing the received CSG ID with the access permission list of the terminal to determine whether to maintain the handover of the terminal; . The method according to claim 1, Wherein the determining comprises: Determines whether the received CSG ID is included in the access allowance list of the terminal, maintains the handover of the terminal when the received CSG ID is included in the access permission list of the terminal, And stops the handover of the access point. 3. The method of claim 2, If the CSG ID of the target cell is not included in the access permission list of the UE, the target MME informs the target CSG base station and the serving MME of the handover failure, and the target BS releases the RRC connection with the UE The access control method comprising the steps of: The method according to claim 1, If the received CSG ID is not included in the access permission list of the UE, indicating to the serving MME that handover of the UE is denied; And Transmitting a message (UE RRC Release message) for releasing the service of the UE to the CSG base station; The access control method further comprising: 1. A target mobility management entity (MME) for performing access control in a wireless communication system, A transmitting and receiving unit for transmitting and receiving signals; And When the handover of the UE is determined, the mobile station receives a UE Allowed CSG List of the UE from a mobility management entity (MME) connected to the serving BS, (CSG) ID from a closed subscriber group (CSG) base station, compares the received CSG ID with the access permission list of the terminal, A control unit for determining whether to maintain overcurrent; Gt; MME. ≪ / RTI > 6. The method of claim 5, Wherein, Determines whether the received CSG ID is included in the access allowance list of the terminal, maintains the handover of the terminal when the received CSG ID is included in the access permission list of the terminal, And stops the handover of the target MME. 6. The method of claim 5, Wherein, When the received CSG ID is included in the access permission list of the UE, maintains the handover of the UE and controls the transmitting and receiving unit to notify the serving MME that the handover of the UE is completed Targeted MME. 6. The method of claim 5, Wherein, If the received CSG ID is not included in the access permission list of the UE, the serving MME is notified that the handover of the UE is denied to the serving MME, and a message for releasing the UE's service (UE RRC Release message ) Of the target MME. A method of access control of a serving mobility management entity (MME) in a wireless communication system, Receiving a handover request message from a serving base station that has determined handover of the mobile station; And The UE transmits a handover request and a UE Allowed CSG List to a target mobility management entity (MME) connected to a closed subscriber group (CSG) ; / RTI > The access permission list of the terminal includes: Wherein the target MME is used to determine whether to maintain a handover of the UE based on a closed subscriber group (CSG) ID reported from the target CSG base station. 1. A serving mobility management entity (MME) for performing access control in a wireless communication system, A transmitting and receiving unit for transmitting and receiving signals; And A target mobility management entity (MME), which receives a handover request message from a serving base station that has determined handover of the mobile station and is connected to a closed subscriber group (CSG) A handover request to the UE and a UE Allowed CSG List of the UE; Lt; / RTI > The access permission list of the terminal includes: Wherein the target MME is used to determine whether to maintain a handover of the terminal based on a closed subscriber group (CSG) ID reported from the target CSG base station.

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