WO2010126344A2

WO2010126344A2 - Method for accessing femto cell

Info

Publication number: WO2010126344A2
Application number: PCT/KR2010/002796
Authority: WO
Inventors: Gi Won Park; Yong Ho Kim; Ki Seon Ryu
Original assignee: Lg Electronics Inc.
Priority date: 2009-05-01
Filing date: 2010-05-03
Publication date: 2010-11-04
Also published as: KR20100119714A; WO2010126344A3

Abstract

Methods for accessing a femto cell using a location based service (LBS) and apparatuses supporting the same are disclosed. A mobile station can access the femto cell efficiently by using its location information acquired through LBS measurement and location information of the femto cell. Also, a network entity can indicate whether the mobile station has accessed the femto cell, by using the location information of the femto cell and the location information of the mobile station. In this case, the location information of the femto cell includes local coordinate information of the femto cell and radius information R of a surrounding radius of the femto cell.

Description

METHOD FOR ACCESSING FEMTO CELL

The present invention relates to a technology of performing communication in a specific femto base station or a specific mobile station of a mobile communication system that includes a macro base station, one or more femto base stations, and one or more mobile stations.

A femto base station is a small-scaled version of a macro base station, and means a base station, which can be provided in either a zone covered by the macro base station or a shaded zone not covered by the macro base station, while performing most of functions of the macro base station. The femto base station has a configuration of a network, which is operated independently. The number of femto base stations that can be provided in downtown or indoor is much more than that of relay base stations.

FIG. 1 is a schematic view illustrating a wireless communication system to which a femto base station is added.

As illustrated in FIG. 1, the wireless communication system to which a femto base station is added includes a femto base station 110, a macro base station, a femto network gateway (FNG) 130, an access service network (ASN) 140, and a connectivity service network (CSN) 150. The macro base station means a general base station of a wireless communication system according to the related art.

The femto base station 100 is operated independently like the macro base station by directly accessing a transmission control protocol/internet protocol (TCP/IP) network, and has coverage of 0.1 ~ 30m. It is assumed that the number of mobile stations that can be occupied by one femto base station is 10 ~ 20. The femto base station 110 may use either the same frequency as that of the macro base station (in case of Intra FA) or another frequency different from that of the macro base station (in case of Inter FA).

The femto base station 110 may be connected with the macro base station through R1 interface to receive a downlink channel of the macro base station. Also, the femto base station 110 may transmit a control signal to the macro base station.

The femto base station 110 can cover an indoor or shaded zone which is not covered by the macro base station, and can support high rate data transmission. The femto base station 110 may be provided within a cell in an overlay type. Alternatively the femto base station 110 may be provided in a zone, which is not covered by the macro base station, in a non-overlay type.

The femto base station 110 is divided into two types. The first type is a closed subscriber group (CSG) femto base station, and the second type is an open subscriber group (OSG) femto base station. The CSG femto base station provides CSG ID(identification) to specific mobile stations by grouping them, wherein the specific mobile stations are those which can access the CSG femto base station. In this case, when the mobile stations provided with CSG ID and mobile stations having no CSG ID access the CSG femto base station, discrimination may be given to such mobile stations. The OSG femto base station is the base station that can be accessed by all the mobile stations.

The FNG 130 is a gateway that controls the femto base station 110 and can be connected with the ASN 140 and the CSN 150 through Rx interface and Ry interface. The femto base station can be served by the CSN 150 through the FNG 230, and the mobile station connected with the femto base station 110 can be served with functions such as authentication and IMS by the CSN 150.

The CSN 150 provides connection of application service such as Internet and VoIP to the mobile station, and also provides authentication and billing functions to the mobile station. The ASN 140 can control the macro base station and manage connection between the macro base station and the CSN 150.

Meanwhile, the aforementioned CSG type femto base station can be divided into two types depending on the possibility of access of an unsubscribed mobile station, i.e., a mobile station to which CSG ID is not given.

The CSG closed type femto base station (CSG-Femto ABS) grants access to subscribed mobile stations only. The mobile station can store CSG closed type femto base station identifiers, grant access of the mobile station, in a white list.

Meanwhile, the CSG open type femto base station (CSG-Open Femto ABS) first supports a service to subscribed mobile stations, and grant access to unsubscribed mobile stations if there are remaining resources. However, unlike the subscribed mobile stations, a service level of the unsubscribed mobile stations can be discriminated.

In the current mobile communication system that uses a femto base station, it is assumed that the CSG type femto base station is divided into two types depending on access grant of unsubscribed mobile stations, as described above. The CSG open type/closed type femto base stations can be identified through partition information from an advanced air interface system configuration descriptor (AAI_SCD) message.

Meanwhile, if the macro base station and the femto base station are provided in a frequency domain, unsubscribed CSG mobile stations connected to the macro base station can sense interference from peripheral femto base stations. In this case, the macro base station can allow the corresponding femto base station not to use certain resource region, thereby controlling interference of the mobile station.

Accordingly, the present invention is directed to a method for accessing a femto cell, which substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method for accessing a femto cell and an apparatus supporting the same, in which a mobile station can access the femto cell efficiently.

Another object of the present invention is to provide a method for accessing a femto cell and an apparatus supporting the same, in which a mobile station can access the femto cell efficiently by using a location based service (LBS) measurement result.

Still another object of the present invention is to provide a method for accessing a femto cell and an apparatus supporting the same, in which a mobile station can access the femto cell efficiently by using its location information, location information of a neighboring base station, and location information of the femto cell.

Further still another object of the present invention is to provide a method for supporting an operation of a femto cell of a low duty mode by using location information of the femto cell and an apparatus supporting the same.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the present invention provides a method for performing communication in a specific femto base station or a specific mobile station of a mobile communication system that includes a macro base station, one or more femto base stations, and one or more mobile stations, and an apparatus for supporting the same.

In a first embodiment of the present invention, a method for accessing a femto cell using a location based service (LBS) comprises transmitting a first message to a macro base station, the first message including a flag requesting location information of the femto cell; receiving a second message from the macro base station, the second message including the location information of the femto cell; receiving a third message from the macro base station, the third message including location information of a neighboring base station; performing the LBS measurement using the location information of the neighboring base station; and accessing the femto cell using the result of the LBS measurement and the location information of the femto cell. In this case, the location information of the femto cell includes local coordinate information of the femto cell and radius information R of a surrounding radius of the femto cell.

In the first embodiment, the first message is one of a ranging request message, a registration request message, and a basic capability negotiation request message, and the second message is one of a ranging response message, a registration response message, and a basic capability negotiation response message. Also, the third message is either a neighboring base station advertisement message or a location based service advertisement message.

The method of the first embodiment further comprises transmitting the result of the location based service measurement to the base station, and receiving a fourth message from the base station, the fourth message indicating access to the femto cell. In this case, the fourth message is either an unsolicited ranging response message or an unsolicited scan response message.

The method of the first embodiment further comprises transmitting a message to the base station, the message including an indicator indicating that the mobile station is located at a radius area of the femto cell.

Alternatively, the method of the first embodiment further comprises transmitting a message to the femto cell, the message including an indicator indicating that the mobile station is located at a radius area of the femto cell.

In the first embodiment, the location based service measurement is performed in accordance with a measurement manner such as round trip delay time measurement, U-TDOA, D-TDOA or TOA.

In a second embodiment of the present invention, a method for accessing a femto cell using a location based service (LBS) comprises receiving a first message from a mobile station, the first message including a flag requesting location information of the femto cell; transmitting a second message to the mobile station, the second message including the location information of the femto cell; transmitting a third message to the mobile station, the third message including location information of a neighboring base station; and receiving a fourth message from the mobile station, the fourth message including the result of the LBS measurement, which is measured using the location information of the neighboring base station. In this case, the location information of the femto cell includes local coordinate information of the femto cell and radius information R of a surrounding radius of the femto cell.

In the second embodiment, the first message is one of a ranging request message, a registration request message, and a basic capability negotiation request message, and the second message is one of a ranging response message, a registration response message, and a basic capability negotiation response message. Also, the third message is either a neighboring base station advertisement message or a location based service advertisement message.

The method of the second embodiment further comprises transferring the result of the location based service measurement to an access service network gateway (ASN-GW), receiving a trigger command message from the access service network gateway, the trigger command message commanding the mobile station to discover the femto cell, and transmitting a message to the mobile station in accordance with the trigger command message, the message indicating the mobile station to discover the femto cell.

The method of the second embodiment further comprises transmitting a message to the base station, the message including an indicator indicating that the mobile station is located at a radius area of the femto cell.

In the second embodiment, the location based service measurement is performed in accordance with a measurement manner such as round trip delay time measurement, U-TDOA, D-TDOA or TOA.

In a third embodiment of the present invention, a mobile station supporting a method for accessing a femto cell using a location based service (LBS) comprises a Tx module transmitting a radio signal; a Rx module receiving a radio signal; and a processor controlling the method for accessing a femto cell using a location based service.

In this case, the processor controls the steps of transmitting a first message to a macro base station using the Tx module, the first message including a flag requesting location information of the femto cell; receiving a second message from the macro base station using the Rx module, the second message including the location information of the femto cell; receiving a third message from the macro base station using the Rx module, the third message including location information of a neighboring base station; performing the LBS measurement using the location information of the neighboring base station; and accessing the femto cell using the result of the LBS measurement and the location information of the femto cell. In this case, the location information of the femto cell includes local coordinate information of the femto cell and radius information R of a surrounding radius of the femto cell.

In the third embodiment, the first message is one of a ranging request message, a registration request message, and a basic capability negotiation request message, and the second message is one of a ranging response message, a registration response message, and a basic capability negotiation response message. Also, the third message is either a neighboring base station advertisement message or a location based service advertisement message.

It is to be understood that the first to third embodiments are only exemplary and explanatory, and various embodiments including technical features of the present invention can be devised by those skilled in the art based on the detailed description of the present invention, which will be described later.

According to the embodiments of the present invention, the following advantages can be obtained.

First of all, the mobile station can access the femto cell efficiently.

Second, the mobile station can access the femto cell efficiently by using the result of location based service (LBS) measurement.

Third, the mobile station can access the femto cell efficiently by using its location information, location information of a neighboring base station, and location information of the femto cell.

Finally, an operation of a femto cell of a low duty mode can be supported by using location information of the femto cell, whereby processing throughput of the mobile station and network entities can be improved.

It is to be understood that the effects that can be obtained by the present invention are not limited to the aforementioned effects, and another effects, which are not described, will be apparent to those skilled in the art to which the present invention pertains, from the following detailed description of the present invention.

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:

FIG. 1 is a schematic diagram illustrating a wireless communication system to which a femto base station is added;

FIG. 2 is a diagram illustrating an example that a mobile station of an idle mode tries to access a femto cell based on location information of a femto base station in accordance with the embodiment of the present invention;

FIG. 3 is a diagram illustrating another example that a mobile station of an idle mode tries to access a femto cell based on location information of a femto base station in accordance with the embodiment of the present invention;

FIG. 4 is a diagram illustrating still another example that a mobile station of an idle mode tries to access a femto cell based on location information of a femto base station in accordance with the embodiment of the present invention;

FIG. 5 is a diagram illustrating further still another example that a mobile station of an idle mode tries to access a femto cell based on location information of a femto base station in accordance with the embodiment of the present invention;

FIG. 6 is a diagram illustrating an example that a mobile station of a normal mode performs handover to a femto cell by using its location information and location information of the femto cell in accordance with the embodiment of the present invention;

FIG. 7 is a diagram illustrating another example that a mobile station of a normal mode performs handover to a femto cell by using its location information and location information of the femto cell in accordance with the embodiment of the present invention;

FIG. 8 is a diagram illustrating an example of a method for accessing a femto base station using a location based service (LBS) based on round trip delay (RTD) in accordance with the embodiment of the present invention;

FIG. 9 is a diagram illustrating an example of a method for accessing a femto base station using a location based service (LBS) based on D-TDOA in accordance with the embodiment of the present invention;

FIG. 10 is a diagram illustrating an example of a method for accessing a femto base station using a location based service (LBS) based on U-TDOA in accordance with the embodiment of the present invention;

FIG. 11 is a diagram illustrating another example of a method for accessing a femto base station using a location based service (LBS) based on round trip delay (RTD) in accordance with the embodiment of the present invention;

FIG. 12 is a diagram illustrating an example of a method for accessing a femto cell using a location based service (LBS) in accordance with the embodiment of the present invention;

FIG. 13 is a diagram illustrating another example of a method for accessing a femto cell using a location based service (LBS) in accordance with the embodiment of the present invention;

FIG. 14 is a diagram illustrating still another example of a method for accessing a femto cell using a location based service (LBS) in accordance with the embodiment of the present invention;

FIG. 15 is a diagram illustrating an example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention;

FIG. 16 is a diagram illustrating another example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention;

FIG. 17 is a diagram illustrating still another example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention;

FIG. 18 is a diagram illustrating further still another example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention;

FIG. 19 is a diagram illustrating further still another example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention; and

FIG. 20 is a diagram illustrating a mobile station and a base station through which the embodiments illustrated in FIG. 2 to FIG. 19 are carried out.

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

The following embodiments are achieved by combination of structural elements and features of the present invention in a predetermined type. Each of the structural elements or features should be considered selectively unless specified separately. Each of the structural elements or features may be carried out without being combined with other structural elements or features. Also, some structural elements and/or features may be combined with one another to constitute the embodiments of the present invention. The order of operations described in the embodiments of the present invention may be changed. Some structural elements or features of one embodiment may be included in another embodiment, or may be replaced with corresponding structural elements or features of another embodiment.

In the description of the drawings, procedures or steps that may make the subject matter of the present invention obscure will be omitted, and procedures or steps that can be understood by the person with ordinary skill in the art will be omitted.

The embodiments of the present invention have been described based on the data transmission and reception between a base station and a mobile station. In this case, the base station means a terminal node (TN) of a network, which performs direct communication with the mobile station. A specific operation which has been described as being performed by the base station may be performed by an upper node of the base station as the case may be.

In other words, it will be apparent that various operations performed for communication with the mobile station in the network which includes a plurality of network nodes (NNs) along with the base station may be performed by the base station or network nodes other than the base station. The base station may be replaced with terms such as a fixed station, Node B, eNode B (eNB), an advanced base station (ABS) and access point.

Also, the mobile station may be replaced with terms such as a user equipment (UE), a subscriber station (SS), a mobile subscriber station (MSS), a mobile terminal (MT), an advanced mobile station (AMS) and a terminal.

Furthermore, a transmitting side means a fixed and/or mobile node that provides data services or voice services while a receiving side means a fixed and/or mobile node that receives data services or voice services. Accordingly, in an uplink, the mobile station could be a transmitting side while the base station could be a receiving side. Likewise, in a downlink, the mobile station could be a receiving side while the base station could be a transmitting side.

The embodiments of the present invention can be supported by standard documents disclosed in at least one of wireless access systems, i.e., IEEE 802 system, 3GPP system, 3GPP LTE system, and 3GPP2 system. Namely, among the embodiments of the present invention, apparent steps or parts which are not described to clarify the technical features of the present invention can be supported by the above standard documents.

Also, all terminologies disclosed herein can be described by the above standard documents. Particularly, the embodiments of the present invention can be supported by one or more of standard documents of IEEE 802.16 system, i.e., P802.16e-2004, P802.16e-2005, P802.16Rev2, and P802.16m.

Hereinafter, the preferred embodiments of the present invention will be described with reference to the accompanying drawings. It is to be understood that the detailed description, which will be disclosed along with the accompanying drawings, is intended to describe the exemplary embodiments of the present invention, and is not intended to describe a unique embodiment with which the present invention can be carried out.

Specific terminologies hereinafter used in the embodiments of the present invention are provided to assist understanding of the present invention, and various modifications can be made in the specific terminologies within the range that they do not depart from technical spirits of the present invention.

In the embodiments of the present invention, a femto cell represents a local area managed by a femto base station, and can be used as the same entity as the femto base station. Also, a macro cell represents a local area managed by a macro base station, and can be used as the same entity as the macro base station. The term, macro base station, is used to discriminate a general base station from the femto base station. In this respect, the macro base station may mean a base station which is generally used.

It is assumed that the embodiments of the present invention support a location based service (LBS). In the 802.16m system (hereinafter, referred to as “16m”), location determining features include AAI based transmission report support for supporting related entities on a network for determining an advanced mobile station (AMS) and/or its location and measurement support on a wireless downlink and a wireless uplink.

Basic functions of the location based service (LBS) are supported by AAI_LBS-ADV message. The AAI_LBS-ADV message is a media access control (MAC) management message broadcasted from an advanced base station (ABS) to provide local location of neighboring ABSs to the AMS. The AMS can use location information of a neighboring base station, which is included in the AAI_LBS-ADV message, to determine its location through triangulation or trilateration. The AAI_LBS-ADV message can further include time and frequency information based on satellite (for example, GPS) to improve throughput of receivers.

In the embodiments of the present invention, it is assumed that a network (for example, home macro advanced base station (HM ABS), FBS, and ASN-GW) previously knows location information (coordinate information and radius information) of a CSG femto cell of the AMS. This is possible when the femto base station (FBS) shares its location information with another network entity through a backbone network.

Also, the AMS and the ASN-GW may previously store CSG information of the AMS. At this time, the CSG information of the AMS can include CSG identifier (CSG ID), HM ABS identifier (HM ABS ID), cell ID, and CSG femto cell location information.

Hereinafter, messages used in the embodiments of the present invention will be described.

The following Table 1 represents one of ranging request message formats that include a request of location information flag.

Table 1

Syntax	Size(bits)	Contents
A_RNG-REQ message format(){
~	~	~
Request of Location Information		If corresponding flag is set to '1', macro base station transmits location information of CSG femto cell to mobile station through A-RNG-RSP.
~	~	~
} // End of A-RNG-REG

Referring to Table 1, the request of location information flag represents that the mobile station (AMS) requests location information of the CSG femto base station to which the mobile station has been subscribed. For example, if the request of location information flag is set to '1', a home macro advanced base station (ABS) transmits a ranging response message including location information of the femto cell to the mobile station (AMS).

If the mobile station transmits the ranging request message of Table 1 to the femto base station, the femto base station can transmit the ranging response message including the location information of the femto cell to the mobile station.

The following Table 2 represents one of ranging response message formats including location information of the femto base station.

Table 2

Sytax	Size(bits)	Contents
A_RNG-RSP message format(){
~	~	~
Coordination information		Local coordinate information of femto cell
Radius of Femto cell surrounding area		Radius from the center of femto cell to surrounding area
~	~	~
} // End of A-RNG-RSP

Referring to Table 2, the A-RNG-RSP message can include coordination information of the femto base station and radius information of femto cell surrounding area representing a predetermined radius from the center of the femto cell to a surrounding area. In other words, the location information of the femto base station can include coordination information and radius information of the femto base station.

The following Table 3 represents one of enabled action triggered TLV parameter formats.

Table 3

Sytax	Size(bits)	Contents
Enabled Action Triggered TLV		Indicates action performed upon reaching trigger condition If bit#0 is set to 1, respond on trigger with AAI_SCN-REPIf bit#1 is set to 1, respond on trigger with AAI_MSHO-REQIf bit#2 is set to 1, on trigger, AMS starts neighboring BS scanning process by sending AAI_SCN-REQIf bit#3 is set to 1, on trigger, AMS starts neighbor BS scanning process by sending A-AAI_SCN-REQ for LBS measurementIf bit#4 is set to 1, on trigger, AMS starts CSG Femto BS scanning process by sending A-AAI_SCN-REQ for its CSG Femto discoverybit#5~bit#7: Reserved. Shall be set to 0.

Referring to Table 3, the enabled action triggered TLV represents an operation to be performed by the AMS. In other words, the enabled action triggered TLV parameter can be represented by a bit map type.

For example, bit #0 of the enabled action triggered TLV parameter indicates transmission of scanning report (MOB_SCN-REP) message, bit #1 indicates transmission of handover request (MOB_MSHO-REQ) message, bit #2 indicates start of neighboring base station scanning process and transmission of scanning request (MOB_SCN-REQ) message, bit #3 indicates transmission of scanning request message for LBS measurement, and bit #4 indicates transmission of scanning request message for CSG femto cell discovery. The other bits #5 to #7 are reserved values and indicate other actions.

The enabled action triggered TLV parameter of Table 3 can be included in the unsolicited ranging response (A-RNG-RSP) message or an unsolicited scanning response (A-SCN-RSP) message.

The following Table 4 and Table 5 respectively represent examples of a subscriber station basic capability request (A-SBC-REQ) message format and a subscriber station basic capability response (A-SBC-RSP) message format, which are used during a basic capability negotiation process.

Table 4

Syntax	Size(bit)	Contents
A_SBC-REQ(){
~	~	~
Request of Location Information	1	If corresponding flag is set to '1', macro base station transmits location information of CSG femto cell to mobile station through A-RNG-RSP.
~	~	~
}// end of A-SBC-REQ

Table 5

Syntax	Size(bit)	Contents
A-SBC-RSP message format (){	-	-
~	~	~
Coordination information		Local coordinate information of femto cell
Radius of Femto cell surrounding area		Radius from the center of femto cell to surrounding area
~
}// End of A-SBC-RSP

The following Table 6 and Table 7 respectively represent registration request (A-REG-REQ) message format and registration response (A-REG-RSP) message format, which are used during a network registration process.

Table 6

Syntax	Size(bit)	Contents
A-REG-REQ message format (){
~	~	~
Request of Location Information	1	If corresponding flag is set to '1', macro base station transmits location information of CSG femto cell to mobile station through A-RNG-RSP.
~	~	~
}// End of A-REG-REQ

Table 7

Syntax	Size(bit)	Contents
A-REG-RSP message format(){
~	~	~
Coordination information		Local coordinate information of femto cell
Radius of Femto cell surrounding area		Radius from the center of femto cell to surrounding area
~	~	~
} // End of A-REG-RSP

For the description of flag and parameter included in the messages of Table 4 to Table 7, refer to the description of Table 2 and Table 3. The flag and parameter of Table 4 to Table 7 can be used to request and receive location information of the CSG femto base station to which the mobile station has been subscribed, during the basic capability negotiation process between the mobile station and the base station or initial registration process of the mobile station.

The following Table 8 represents an example of a scanning response message format that can be used in the embodiments of the present invention.

Table 8

Syntax	Size (bit)	Contents
AAI_SCN-RSP_Message_format() {
~	~	~
Scanning type		0b000: Scanning without association0b001: Scanning with association level 0: association without coordination0b010: Scanning with association level 1: association with coordination0b011: Scanning with association level 2: network assisted association0b100: Scanning of Femtocell BSs0b101-0b111: Reserved
~	~	~
} //End of AAI_SCN-RSP

Referring to Table 8, if a scanning type parameter is set to 0b000, it represents scanning without association. If the scanning type parameter is set to 0b001, it represents scanning with association level 0 and without coordination. If the scanning type parameter is set to 0b010, it represents scanning with association level 1 and with coordination. If the scanning type parameter is set to 0b011, it represents scanning with association level 2 and network assisted association. If the scanning type parameter is set to 0b100, it represents FBS scanning. The scanning type parameters 0b101 to 0b111 may be set to reserved values.

The scanning response message of Table 8 can be used to report scanning action type of the mobile station from the base station to the mobile station when the mobile performs scanning action.

The following Table 9 represents another example of a ranging response message format that can be used in the embodiments of the present invention.

Table 9

Syntax	Size(bit)	Contents
A-RNG-RSP message format(){
~	~	~
TA(Timeing Advance)
Radius of Femto cell surrounding area(R)		Radius from the center of femto cell to surrounding area
Enabled Action Triggered TLV
~	~	~
} // End of A-RNG-RSP

Referring to Table 9, Femto cell radius information (R) represents a radius from the center of a CSG femto cell to which the AMS has been subscribed to the surrounding area. Also, an enabled action triggered TLV parameter is the same as that described in Table 3. In this case, the TA value and radius information (R) can selectively be included in the ranging response message.

The following Table 10 represents an example of a paging message format that can be used in the embodiments of the present invention.

Table 10

Syntax	Size(bit)	Notes
AAI_PAG-ADV_Message_format() {
~	~	~
Num_Temp ID		The number of temporary ID assigned to AMS which is in the paging group.
For (j=0: j< Num_Temp ID: j++) {
Temporary ID
Action Code		0b00: Perform network re-entry0b01: Perform ranging to establish location0b10: Perform LBS measurement0b11: reserved
}
~	~	~
} //End of AAI_PAG-ADV

Referring to table 10, Num-Temp ID parameter represents the number of temporary identifiers assigned to AMS which is in a paging group, the temporary identifier represent tentatively used identifier until the network authentication process is completed, and the action code indicates actions that the AMS has to perform.

If the action code is set to 0b00, the mobile station performs a network reentry process. If the action code is set to 0b01, the mobile station performs a ranging process for location update. Also, if the action code is set to 0b10, the mobile station performs LBS measurement. The value 0b11 can be set to a reserved value.

The embodiments of the present invention, which will be described hereinafter, can be performed using the messages or parameters described in Table 1 to Table 10.

Method for accessing a femto cell based on location information of the femto cell

FIG. 2 is a diagram illustrating an example that a mobile station of an idle mode tries to access a femto cell based on location information of a femto base station in accordance with the embodiment of the present invention.

Location information of the femto cell used in FIG. 2 can include coordination information representing a local coordinate of the femto cell and radius information (hereinafter, referred to as ‘R’) of a surrounding area radius of the femto cell. Namely, in the embodiments of the present invention, the AMS can efficiently access the femto cell by using the coordination information and radius information R of the femto cell. At this time, it is preferable that the radius information R represents a radius the same or greater than that covered by the femto cell as much as a predetermined size.

Referring to FIG. 2, the AMS intends to access a femto cell from a serving cell that currently provides a service, wherein the femto cell supports a closed service group (CSG) to which the AMS has been subscribed. At this time, a macro cell area where the CSG femto cell that can be accessed by the AMS is located will be referred to as a home macro cell (HMC) area. In other words, the AMS can access the CSG femto cell from the HMC area by performing scanning for discovering the CSG femto cell at the CSG femto cell surrounding area.

The AMS can identify whether the AMS has accessed the CSG femto cell surrounding area from the HMC area, by using the location information of the femto cell. Namely, the AMS can identify the exact location of the CSG femto cell by using the coordination information and radius information R of the CSG femto cell.

In the embodiments of the present invention, the AMS can acquire the location information of the CSG femto cell through a super frame header (SFH), neighboring base station advertisement (AAI_NBR-ADV) message or additional system information, which is broadcasted from a serving base station, the HMC macro base station and the CSG femto cell.

Furthermore, the AMS can request the base station ABS of the location information of the femto cell by transmitting a subscriber mobile station capability request (AAI_SBC-REQ) message, a registration request (AAI_REG-REQ) message or a ranging request (AAI-RNG-REQ) message to the base station. The base station ABS can transmit the location information of the CSG femto cell to the AMS through a subscriber station mobile station capability response (AAI_SBC-RSP) message, a registration response (AAI_REG-RSP) message or a ranging response (AAI-RNG-RSP) message.

Furthermore, in the embodiments of the present invention, it may be assumed that the AMS or network (ABS, paging controller, etc.) previously knows the location information of the femto cell.

FIG. 3 is a diagram illustrating another example that a mobile station of an idle mode tries to access a femto cell based on location information of a femto base station in accordance with the embodiment of the present invention.

In the method described in FIG. 3, the AMS discovers the CSG femto cell by directly scanning the location of the CSG femto cell. Also, it is assumed that the AMS is in an idle mode.

The AMS of the idle mode can move to the HMC area where the CSG femto cell is located (S301).

In the embodiments of the present invention, it is assumed that the mobile station of the idle mode performs location update if a paging group is changed but the AMS performs location update at the macro base station where the CSG femto cell to which the AMS has been subscribed is located. Namely, even though the macro base station belongs to the same paging group, the AMS can perform location update with the macro base station at the HMC that includes the CSG femto cell.

Accordingly, the AMS can transmit the ranging request (A-RNG-REQ) message to the HMC base station to perform location update (UP) with the HMC base station (S302).

At this time, the AMS can transmit the ranging request (A-RNG-REQ) message to the home macro ABS together with a request of location information flag to request the home macro ABS of the location information of the femto cell (see Table 1).

If the request of location information flag within the RNG-REQ message transmitted from the AMS is set to ‘1’, the HMC ABS transmits a ranging response (A-RNG-RSP) message, which includes location information including coordination information and radius information R of the CSG femto cell, to the AMS (S303) (see Table 2).

The HMC ABS can periodically broadcast a location based service advertisement (A-LBS-ADV) message to all mobile stations located within the HMC area. At this time, the A-LBS-ADV message can include location information associated with the location of neighboring base stations (S304).

The AMS can periodically perform a scanning process for location based service (LBS) measurement by using the location information of the neighboring base stations, which is included in the A-LBS-ADV message received from the home macro ABS. The AMS can measure its location information based on the LBS measurement result (S305).

The AMS can determine whether the AMS is located near the CSG femto cell, by combining its location information with the location information of the CSG femto cell, which is received through the A-RNG-RSP message (S306).

If it is determined that the AMS is located near the CSG femto cell, the AMS performs CSG femto cell scanning to discover the CSG femto cell (S307).

If the AMS discovers its CSG femto cell during the scanning process, the AMS can transmit and receive ranging (AAI_RNG-REQ/RSP) messages to and from the CSG femto cell to perform a location update process with the CSG femto cell (S309, S310).

FIG. 4 is a diagram illustrating still another example that a mobile station of an idle mode tries to access a femto cell based on location information of a femto base station in accordance with the embodiment of the present invention.

In the method described in FIG. 4, the network determines whether the AMS has entered the CSG femto cell surrounding area, based on the location information of the AMS, and requests the AMS of scanning for discovering the CSG femto cell. Also, in FIG. 4, it is assumed that the AMS is in an idle mode.

As the AMS of the idle mode moves to the home macro cell where the CSG femto cell is located, the AMS can perform location update with the home macro base station (HM ABS). At this time, the AMS sets a request of femto cell’s location information flag of the A-RNG-REQ message to ‘1’ to request the base station of location information of the CSG femto cell. The base station transmits A-RNG-RSP message, which includes location information (for example, coordination information and radius information) of the femto cell, to the AMS in response to the request (S401).

The HM ABS periodically broadcasts a location based service advertisement (A-LBS-ADV) message to all mobile stations located within its area, wherein the A-LBS-ADV message includes a local coordinate value of a neighboring base station (S402).

The HM ABS can transmit a paging message (for example, A-PAG-ADV) to a paging listening interval of the AMS. At this time, the HM ABS transmits a paging message of which action codes 0b01 (perform ranging to establish location) and 0b10 (perform LBS measurement) are set to ‘1’, to the AMS (S403) (see Table 3).

In the step S403, the action code 0b01 indicates to perform ranging to establish location update, and the action code 0b10 indicates the mobile station to measure LBS. In other words, the action code 0b10 set to ‘1’ is only transferred to the AMS which will perform LBS measurement. However, in FIG. 4, the step S403 may be skipped depending on user’s requirements or channel status.

The AMS can perform a scanning process for LBS measurement by using location information of a neighboring base station, which is included in the A-LBS-ADV message received from the HM ABS. The AMS can measure its location information by using the LBS measurement value (S404).

The AMS can perform ranging with the HM ABS in accordance with action code 0b01 included in the A-PAG-ADV message received in the step S403. At this time, the AMS can transmit the LBS measurement result and/or its location information acquired based on the LBS measurement to the HM ABS (S405).

The HM ABS transfers the location information of the AMS, which is acquired from the AMS, to an access service network gateway (ASN-GW) (S406).

The ASN-GW can determine whether the AMS has entered the CSG femto cell surrounding area, by comparing location information (i.e., coordinate information and radius information R of the CSG femto cell) of the CSG femto cell of the AMS with location information of the AMS, which is acquired in the step S406 (S407).

If it is determined that the AMS enters the CSG femto cell surrounding area, the ASN-GW can trigger CSG femto cell discovery to the AMS (S408).

If a trigger command of the CSG femto cell discovery of the AMS is received from the ASN-GW, the HM ABS can request the AMS of scanning for CSG femto cell discovery by transmitting an unsolicited A-RNG-RSP message to the AMS, wherein the unsolicited A-RNG-RSP message includes an enabled action triggered TLV parameter (see Table 3) (S409).

In the step S409 of FIG. 4, it is assumed that a bit #4 of the enabled action triggered TLV parameter is set to ‘1’. Accordingly, the AMS can transmit a scanning request message to the HM ABS to discover the CSG femto cell. Also, the AMS can perform scanning for CSG femto cell discovery (S410).

The AMS can perform a ranging process for location update with the CSG femto cell if its CSG femto cell is discovered during the scanning process (S411 ~ S413).

FIG. 5 is a diagram illustrating further still another example that a mobile station of an idle mode tries to access a femto cell based on location information of a femto base station in accordance with the embodiment of the present invention.

In FIG. 5, the AMS performs a CSG discovery result by directly scanning the location of the CSG femto cell. In this case, it is assumed that the AMS is in an idle mode.

As the AMS of the idle mode moves to the home macro cell ABS where the CSG femto cell is located, the AMS can perform location update with the home macro base station (HM ABS). At this time, the AMS transmits a ranging request message, which includes a request of femto cell location information flag, to the MH ABS during location update, and the MH ABS transmits a ranging response message, which includes location information of the CSG femto cell, to the AMS (S501).

The HM ABS periodically broadcasts a location based service advertisement (A-LBS-ADV) message to mobile stations located within its area, wherein the A-LBS-ADV message includes location information (for example, coordinate information, etc.) of a neighboring base station (S502).

The AMS can perform scanning for LBS measurement based on the location information of the neighboring base station, which is included in the A-LBS-ADV message, before performing periodic ranging. The AMS can acquire its location information through the scanning process (S503).

The AMS can transfer its location information to the HM ABS through periodic ranging, wherein the location information is the result of the LBS measurement (S504).

The AMS can determine whether it has entered the CSG femto cell surrounding area, by combining its location information with location information of the CSG femto cell, which is received from the HM ABS through periodic ranging (S505).

If it is determined that the AMS has entered the CSG femto cell surrounding area, the AMS can trigger CSG femto cell discovery. Accordingly, the AMS can perform scanning for CSG femto cell discovery (S506).

The AMS can perform a ranging process for location update with the CSG femto cell if its CSG femto cell is discovered during the scanning process (S507 ~ S509).

FIG. 6 is a diagram illustrating an example that a mobile station of a normal mode performs handover to a femto cell by using its location information and location information of the femto cell in accordance with the embodiment of the present invention.

Referring to FIG. 6, the mobile station AMS can perform a handover process by moving to the home macro cell where the CSG femto cell is located. Accordingly, the AMS can transmit a handover request (A-MOB_MSHO-REQ) message, which includes context information of the AMS, to a serving base station (serving ABS). At this time, the context information of the AMS can include one or more of MAC address of the AMS, serving base station identifier (S-ABS ID), serving cell identifier (Cell ID), FBS identifier (FBS ID), HMC ID, and HM ABS ID (S601).

The serving base station can transfer handover associated information to the HM ABS (not shown). Also, the HM ABS can transfer the context information of the AMS to the ASN-GW (S602).

The serving base station transmits a handover response (A-MOB_BSHO-RSP) message to the AMS in response to the handover request message of the AMS (S603). The AMS transmits a handover indication (A-MOB_MSHO-IND) message to the serving base station to identify and complete handover (S604).

If the AMS does not know location information of the CSG FBS to which the AMS has been subscribed, the AMS requests the serving base station of location information of the CSG FBS in step S601, and acquires location information of the CSG FBS from the serving base station through S603. Alternatively, the AMS can acquire the location information of the CSG FBS through a ranging response message transmitted from the base station during a ranging process performed during a network reentry process with the HM ABS.

As the steps S601 to S604 are performed, the AMS can perform handover to the HM ABS where the CSG femto base station, to which the AMS has been subscribed, is located (S605).

The HM ABS can periodically broadcast a location based service advertisement (A-LBS-ADV) message to mobile stations (AMS) located within its area, wherein the A-LBS-ADV message includes location information of a neighboring base station (S606).

The AMS can perform a scanning process for location based service (LBS) measurement by using the location information of the neighboring base station, which is included in the A-LBS-ADV message received from the home macro ABS. The AMS can acquire its location information through the scanning process (S607).

The AMS can transmit the ranging request message, which includes AMS location information, to the HM ABS through periodic ranging, wherein the location information is the result of the LBS measurement. At this time, the ranging request message can further include a request of femto cell location information flag. If a request of femto cell location information flag within the A-RNG-REQ message transmitted from the AMS is set to ‘1’, the HM ABS transmits the A-RNG-RSP message, which includes location information (e.g., coordinate information and radius information) of the CSG femto cell, to the AMS (S608).

Preferably, the step S608 of FIG. 6 is performed within the cell area of the ABS where the CSG femto cell of the AMS is located. Accordingly, it is preferable that the AMS does not transmit its location information to the corresponding macro base station at the cell area of the ABS having no CSG femto cell.

The HM ABS acquires the location information of the AMS, which is the LBS measurement result, from the AMS and then transmits the acquired location information to the ASN-GW (S609).

The ASN-GW compares location information of the CSG femto cell of the AMS with the location information of the AMS, and if it is determined that the AMS has entered the CSG femto cell surrounding area, triggers the CSG discovery process of the AMS (S610, S611).

The ASN-GW determines a neighboring level between the AMS and the CSG femto cell surrounding area depending on whether the AMS has been located within a surrounding radius R at a place where the femto base station is located. The surrounding radius R may be used by the AMS or the network at an appropriate value without mutual negotiation, or may be used by mutual negotiation between the AMS and the network to optimize corresponding action. Also, when the AMS performs network reentry to the FBS, the value R may be negotiated between the AMS and the network, or the macro base station may broadcast the value R as system information.

If the AMS previously knows the location information of its CSG FBS, the AMS does not need to transmit its location, which is measured during periodic ranging, to the HM ABS. For example, the AMS requests a scanning interval for scanning a femto cell at a place (surrounding radius R) to which the CSG femto base station is adjacent based on its location information measured in step S607, through a scanning request message, and receives the scanning interval through a scanning response message. Accordingly, the AMS can receive the interval sufficient for discovering the CSG femto base station through scanning interval negotiation of one time. If the CSG femto base station is initially discovered, the AMS can end the negotiated scanning action and report it to the HM ABS.

Referring to FIG. 6 again, if a trigger command for CSG femto cell discovery of the AMS is received from the ASN-GW, the HM ABS can request the AMS of scanning for CSG femto cell discovery by transmitting the unsolicited A-RNG-RSP message to the AMS (S612).

In this case, for the unsolicited A-RNG-RSP message format, refer to Table 3. Accordingly, the HM ABS sets a bit #4 of the enabled action triggered TLV parameter to ‘1’ and transmits it to the AMS. In other words, the HM ABS can command the mobile station to start the CSG femto cell discovery action.

In the step S612, when transmitting the unsolicited ranging response message to the AMS, the HM ABS can previously allocate the scanning interval to the AMS, so that the AMS can perform the scanning action. In this case, the ABS can set a bit #5 of the enabled action triggered TLV parameter, which is a reserved bit of Table 3, to ‘1’ and transmit it to the AMS. Also, the ABS can transmit a scanning interval TLV parameter indicating the scanning interval together with the enabled action triggered TLV parameter. At this time, it is assumed that the bit #5 of the enabled action triggered TLV parameter indicates the AMS to perform CSG femto cell scanning for a scanning interval indicated by a given scanning interval TLV parameter. Accordingly, the AMS can directly perform the scanning action without transmitting the A-MOB_SCN-REQ to the HM-ABS.

Alternatively, the HM ABS transmits the unsolicited scanning response message to the AMS instead of the unsolicited ranging response message in step S612, and allocates a scanning interval for the AMS to the unsolicited scanning response message and transmits it to the AMS, whereby the AMS can perform the scanning action without additional scanning interval negotiation.

Referring to FIG. 6 again, the AMS can perform scanning for CSG femto cell discovery based on the parameters received in the step S612 (S613).

The AMS can perform handover to the corresponding CSG femto cell if its CSG femto cell is discovered through scanning (S614 ~ S617).

FIG. 7 is a diagram illustrating another example that a mobile station of a normal mode performs handover to a femto cell by using its location information and location information of the femto cell in accordance with the embodiment of the present invention.

Unlike FIG. 6, in the embodiment of the present invention described with reference to FIG. 7, the mobile station performs scanning for CSG discovery by directly detecting a femto cell surrounding area, and if the CSG femto cell is discovered, performs handover to the CSG femto cell. However, since steps S701 to S708 of FIG. 7 are similar to the steps 601 ~ S608 of FIG. 6, their description will refer to the corresponding description of FIG. 6.

The AMS can determine whether it has entered the CSG femto cell surrounding area, by combining its location information with location information of the CSG femto cell, which is received from the HM ABS through periodic ranging (S709).

If it is determined that the AMS has entered the CSG femto cell surrounding area, the AMS can trigger CSG femto cell discovery. Accordingly, the AMS can perform scanning for CSG femto cell discovery (S710).

The AMS can perform a handover process to the CSG femto cell if its CSG femto cell is discovered during the scanning process (S711 ~ S714).

In FIG. 2 to FIG. 7 as described above, the mobile station AMS transmits the ranging message, which includes the request of femto base station location information flag, to the macro base station or the femto base station during the ranging process for location update of the idle mode or the periodic ranging process of the normal mode, and receives the ranging response message, which includes the location information of the femto base station. However, the request of femto base station location information flag and the location information of the femto base station can be transmitted and received between the AMS and the macro base station (ABS) or the femto base station (FBS) during the basic capability negotiation process or the network registration process (see Table 4 to Table 7).

Method for accessing a femto cell based on round trip delay (RTD)

In the embodiments of the present invention, which will be described later, it is assumed that the mobile station AMS of the normal mode previously knows location information of the CSG femto cell.

In the embodiments of the present invention, when performing a network entry process to the home macro cell, the AMS reports location information of the CSG femto cell to the home macro base station (HM ABS) through the basic capability negotiation process (AAI_SBC-REQ/RSP) or registration process (AAI_REG-REQ/RSP). In this case, the home macro cell (HMC) and the ASN-GW can acquire the location information of the CSG femto cell of the AMS.

Also, the network can previously know the location information of the femto base stations (FBSs) and the AMS can report ID of the CSG femto base station to which the AMS has been subscribed, during the network entry process, whereby the network can map the location relation between the AMS and the CSG femto base station.

Also, it is assumed that both the AMS and the network can previously know the location information of the CSG femto base station, to which the AMS has been subscribed.

FIG. 8 is a diagram illustrating an example of a method for accessing a femto base station using a location based service (LBS) based on round trip delay (RTD) in accordance with the embodiment of the present invention.

Referring to FIG. 8, the mobile station AMS can perform a handover process by moving to the home macro cell where the CSG femto cell is located. Accordingly, the AMS can transmit a handover request (AAI_MSHO-REQ) message, which includes context information of the AMS, to a serving base station (serving ABS). At this time, the context information of the AMS can include one or more of MAC address of the AMS, serving base station identifier (S-ABS ID), serving cell identifier (Cell ID), FBS identifier (FBS ID), HMC ID, and HM ABS ID (S801).

The serving base station can transfer handover associated information to the HM ABS (not shown). Also, the HM ABS can transfer the context information of the AMS to the ASN-GW (S802).

The serving base station transmits a handover response (AAI_BSHO-RSP) message to the AMS in response to the handover request message (S803). The AMS transmits a handover indication (AAI_MSHO-IND) message to the serving base station to identify and complete handover (S804).

As the steps S801 to S804 are performed, the AMS can perform handover to the HM ABS where the CSG femto base station, to which the AMS has been subscribed, is located (S805).

After performing handover, the AMS can perform a network reentry process to access the HM ABS. In other words, the AMS transmits a ranging request message for initial ranging to the HM ABS, and receives a ranging response message, which includes information required for the network reentry process, from the base station (S806).

If the AMS does not know location information of the CSG FBS to which the AMS has been subscribed, the AMS can receive the location information of the CSG FBS from the serving base station in step S803. Alternatively, the AMS can receive the location information of the CSG femto cell through the ranging response message during the network reentry process with the HM ABS. At this time, the serving base station or the HM ABS can transfer radius information R indicating a femto base station (FBS) surrounding area radius value together with the location information of the CSG femto cell when transferring the location information of the CSG femto cell.

The AMS can receive A-NBR-ADV message, which includes location information of a neighboring base station, from the HM ABS. At this time, the location information of the neighboring base station can include local coordinate information of the neighboring base station (S807).

The AMS can perform a scanning process to calculate its location information. Accordingly, the AMS transmits a scanning request (AAI_SCN-REQ) message to the HM ABS to perform scanning for the neighboring base station (S808).

The HM ABS transmits a scanning response (AAI_SCN-REQ) message to the AMS in response to the scanning request message of the AMS (see Table 8). The scanning response message can include a report mode parameter indicating a scanning result report and a report metric parameter indicating a scanning type. In this case, the report mode parameter is set to indicate periodic report (0b01: periodic report), and the report metric parameter is set to indicate a bitmap (bit 3: BS RTD) indicating round trip delay based report (S809).

The AMS can transmit the ranging request message to the HM ABS and neighboring base stations, respectively to measure the round trip delay (RTD) (S810).

Also, the AMS can receive a ranging response message (A_RNG-RSP) (see Table 9), which includes a timing advance (TA) value, from the HM ABS and the neighboring base stations in response to the ranging request message (S811).

The AMS can calculate downlink round trip delay (DL RTD) value based on the time when the ranging response message is received and the TA value (S812).

The AMS can transmit the scanning report (AAI_SCN-REP) message to the HM ABS, wherein the scanning report message includes the DL RTD value which is the measurement result value (S813).

The HM ABS can acquire the location information of the AMS based on the DL RTD value transmitted from the AMS. Also, the HM ABS transfers the DL RTD values to the access service network gateway (ASN-GW) (S814).

The ASN-GW can determine the location of the AMS by comparing location information of the CSG femto cell of the AMS, which is acquired through the basic capability negotiation (AAI_SBC-REQ/RSP) process or the network registration (AAI_REG-REQ/RSP) process during network reentry, with the location information of the AMS, which is acquired through the DL RTD based LBS measurement result (S815).

The ASN-GW can determine a neighboring level between the AMS and the CSG femto cell depending on whether the AMS has been located within a surrounding radius R of the femto base station (FBS). The surrounding radius R may be used by the AMS or the network at an appropriate value without mutual negotiation, or may be used by mutual negotiation between the AMS and the network to optimize corresponding action. For example, when the AMS performs network reentry to the HM ABS, the value R may be negotiated between the AMS and the network, or the ABS may broadcast the value R as system information.

If it is determined that the AMS is adjacent to the CSG femto cell, the ASN-GW can trigger the CSG discovery process (S816).

If the trigger command of the CSG femto cell discovery of the AMS is received from the ASN-GW, the HM ABS can transmit an unsolicited ranging response (AAI_RNG-RSP) message to the AMS. Namely, the HM ABS can request the AMS of scanning for CSG femto cell discovery (S817).

In this case, the unsolicited ranging response message can include an enabled action triggered TLV parameter, and it is assumed that a bit #4 of the enable action triggered TLV parameter is set to ‘1’ (see Table 3).

The AMS can perform scanning for CSG femto cell discovery, and can perform handover to the corresponding CSG femto cell if its CSG femto cell is discovered during the scanning process (S818 ~ S820).

In another aspect of the present invention described in FIG. 8, when transmitting the unsolicited ranging response message to the AMS in step S817, the HM ABS can allocate a scanning interval to the AMS so that the AMS can perform scanning. In this case, a bit #5 if the enabled action triggered TLV parameter is set to ‘1’. At this time, it is assumed that the bit #5 of the enabled action triggered TLV parameter indicates the AMS to perform CSG femto cell scanning for a scanning interval indicated by a given scanning interval TLV parameter. Accordingly, the HM ABS can transmit the unsolicited ranging response message, which includes the scanning interval TLV parameter, to the AMS. In this case, the AMS can directly perform CSG scanning without transmitting the AAI_SCN-REQ to the HM-ABS.

Alternatively, the HM ABS can transmit the unsolicited scanning response (AAI_SCN-RSP) message to the AMS instead of the unsolicited ranging response message in step S817. At this time, the HM ABS allocates a scanning interval for the AMS to the unsolicited scanning response message and transmits it to the AMS, whereby the AMS can perform the scanning action without additional scanning interval negotiation. In this case, in the embodiment of the present invention, a new scanning type for CSG femto cell scanning is defined, and an unsolicited scanning response message including the new scanning type (scanning type: 0b100; scanning of femto cell BS) can be transmitted.

In another aspect of the present invention, the step S815 can be performed by the HM ABS not the ASN-GW. For example, the HM ABS can directly perform trigger for CSG femto cell discovery based on the location information of the AMS and the location information of the CSG femto cell, which are identified based on the RTD value.

FIG. 9 is a diagram illustrating an example of a method for accessing a femto base station using a location based service (LBS) based on D-TDOA in accordance with the embodiment of the present invention.

Since steps S901 to S907 of FIG. 9 are the same as the steps S801 to S808 of FIG. 8, their description will be replaced with that of FIG. 8. However, unlike FIG. 8, a bit #4 of a report metric bitmap of a scanning response (AAI_SCN-RSP) message to a scanning request message is set to 1 and thus a scanning type is downlink time difference of arrival (D-TDOA) in FIG. 9 (S909).

The AMS scans the HM ABS and neighboring base stations and measures a relative delay (RD) value between the HM ABS and the neighboring base station (S910).

The AMS transmits AAI_SCN-REP (measurement report) message, which includes the measured relative delay (RD) value, to the HM ABS (S911).

The HM ABS can identify the location of the AMS based on the RD value transmitted from the AMS. Also, the HM ABS transfers the RD values to the ASN-GW (S912).

Afterwards, the ASN-GW can identify whether the AMS has accessed the CSG femto cell, by using the location information of the CSG femto cell of the AMS, which is acquired during network initial entry of the AMS or basic capability negotiation process, and the location information of the AMS, which is acquired during the LBS measurement process based on D-TDOA. Also, the ASN-GW can trigger the CSG femto cell discovery process. Hereinafter, since steps S913 to S918 are the same as the steps S815 to S820 of FIG. 8, their description will be replaced with that of FIG. 8.

FIG. 10 is a diagram illustrating an example of a method for accessing a femto base station using a location based service (LBS) based on U-TDOA in accordance with the embodiment of the present invention.

Since steps S1001 to S1007 of FIG. 10 are the same as the steps S801 to S808 of FIG. 8, their description will be replaced with that of FIG. 8. However, unlike FIG. 8, a bit #5 of a report metric bitmap of a scanning response (AAI_SCN-RSP) message to a scanning request message is set to 1 and thus a scanning type is uplink time difference of arrival (U-TDOA) in FIG. 10 (S1009).

The AMS scans the HM ABS and neighboring base stations to measure a carrier to interference and noise ratio (CINR) value and a signal to interference ratio (SINR) value of each of the HM ABS and the neighboring base stations and report the measured CINR and SINR values to the HM ABS through a scanning report message (S1010).

The AMS transmits a ranging request message for obtaining UL RTD to the HM ABS and the neighboring base stations, respectively (S1011).

The AMS can receive a ranging response message, which includes a timing advance (TA) value, from the HM ABS and the neighboring base stations in response to the ranging request message (S1012).

The base stations which have received the ranging request message from the AMS can calculate the UL TDOA to exchange the measured UL TDOA value between each other. At this time, the HM ABS can acquire the location information of the AMS based on the measured UL TDOA value (S1013).

The HM ABS can transfer the measured UL TDOA value and the UL TDOA value exchanged between the neighboring base stations to the ASN-GW (S1014).

Afterwards, the ASN-GW can identify whether the AMS has accessed the CSG femto cell, by using the location information of the CSG femto cell of the AMS, which is acquired during network initial entry of the AMS or basic capability negotiation process, and the location information of the AMS, which is acquired during the LBS measurement process based on D-TDOA. Also, the ASN-GW can trigger the CSG femto cell discovery process. Hereinafter, since steps S1015 to S1020 are the same as the steps S815 to S820 of FIG. 8, their description will be replaced with that of FIG. 8.

FIG. 11 is a diagram illustrating another example of a method for accessing a femto base station using a location based service (LBS) based on round trip delay (RTD) in accordance with the embodiment of the present invention.

In the method described in FIG. 11, the network determines whether the AMS has entered the CSG femto cell surrounding area, based on the location information of the AMS, and requests the AMS of scanning for discovering the CSG femto cell. Also, in FIG. 11, it is assumed that the AMS is in an idle mode.

The HM ABS can transmit a paging message (for example, A-PAG-ADV) to a paging listening interval of the AMS. At this time, the HM ABS transmits a paging message of which action codes 0b01 (perform ranging to establish location) and 0b10 (perform LBS measurement) are set to ‘1’, to the AMS, wherein, for the used paging message, refer to Table 10 (S1102).

The HM ABS periodically broadcasts A-NBR-ADV message, which includes location information of a neighboring base station, to mobile stations located within its area. In this case, the location information of the neighboring base station can include a local coordinate value of the neighboring base station (S1103).

The AMS transmits AAI_SCN-REQ message to the HM ABS to perform scanning for calculating its location information (S1104).

The HM ABS transmits AAI_SCN-RSP message to the AMS. In this case, a report mode field included in the AAI_SCN-RSP message is set to a value 0b01 indicating periodic report, and a report metric field is set to a value Bit 3 indicating RTD (S1105).

The AMS can transmit the ranging request message to the HM ABS and neighboring base stations, respectively, to measure the round trip delay (RTD) (S1106). The HM ABS and the neighboring base stations can respectively transmit the ranging response message, which includes a timing advance (TA) value, to the AMS (S1107).

The AMS can calculate a round trip delay (RTD) value based on the time when the ranging request message is transmitted, the time when the ranging response message is received, and the TA value included in the ranging response message (not shown). Accordingly, the AMS can transmit the AAI_SCN_REP (measurement report) message, which includes the measured RTD value, to the HM ABS (S1108).

The HM ABS can acquire the location information of the AMS based on the RTD value transmitted from the AMS. Also, the HM ABS transfers the RTD values to the access service network gateway (ASN-GW) (S1109).

Afterwards, the ASN-GW can identify whether the AMS has accessed the CSG femto cell, by using the location information of the CSG femto cell of the AMS, which is acquired during network initial entry of the AMS or basic capability negotiation process, and the location information of the AMS, which is acquired during the LBS measurement process based on RTD. Also, the ASN-GW can trigger the CSG femto cell discovery process of the AMS. Hereinafter, since steps S1110 to S1115 are the same as the steps S815 to S820 of FIG. 8, their description will be replaced with that of FIG. 8.

Although the HM ABS and/or the ASN-GW identifies the location information of the AMS based on the RTD value in FIG. 11, the HM ABS and/or the ASN-GW can identify the location information of the AMS by using D-TDOA or U-TDOA described in FIG. 9 and FIG. 10 as well as the RTD value.

FIG. 12 is a diagram illustrating an example of a method for accessing a femto cell using a location based service (LBS) in accordance with the embodiment of the present invention.

In FIG. 12, it is assumed that the mobile station AMS is in an idle mode. The AMS of the idle mode moves to the HM ABS where the CSG femto cell to which the AMS has been subscribed is located (S1201).

The AMS can perform location update with the HM ABS (S1202).

The HM ABS transfers information of the AMS and the ABS, which is received through location update with the AMS, to a paging controller (PC) or an access service network gateway (ASN-GW). At this time, the information transferred to the ASN-GW can include CSG information. Namely, one or more of CSG ID, home macro BS ID, home macro cell ID, serving BS ID, serving cell ID, MS MAC address and AMS location information can be included in the CSG information (S1203).

The paging controller (PC) can compare the AMS information, ABS information and CSG information, which are received through the location update process, with its AMS information and its ABS information (for example, CSG femto cell information and home macro base station information) (S1204).

If the AMS enters the HM ABS area where the CSG femto cell is locate, the paging controller can transmit a trigger message to the HM ABS to trigger LBS measurement to the AMS (S1205).

The HM ABS can periodically transfer the AAI_LBS-ADV message to the AMS. In this case, the AAI_LBS-ADV message can include location information (for example, local coordinate information) of a neighboring base station (S1206).

The HM ABS can transmit an unsolicited ranging response (AAI_RNG-RSP) message to the AMS so that the AMS can perform LBS measurement, wherein a bit #3 of the enabled action triggered TLV is set to ‘1’ in the unsolicited ranging response message (S1207).

The AMS can perform scanning for LBS measurement by using the location information of the neighboring base station, which is received in the step S1206. The AMS can identify its location by using the LBS measurement result (S1208).

The AMS transfers the A-MOB_SCN-REP message, which includes the LBS measurement result (TDOA or TOA, etc.), to the HM ABS (S1209).

The HM ABS transfers the LBS measurement result received from the AMS, to the paging controller (PC) (S1210).

The paging controller can obtain the location information of the AMS based on the LBS measurement result transmitted from the AMS and the HM ABS. At this time, it is assumed that the paging controller already knows the location information of the CSG femto cell. Accordingly, the paging controller can identify whether the AMS is located at the CSG femto cell surrounding area, by using the location information of the AMS and the location of the CSG femto cell (S1211).

If the paging controller determines that the AMS is located at the CSG femto cell surrounding area, the paging controller can trigger the CSG femto cell discovery process to the HM ABS, whereby the AMS can discover the CSG femto cell (S1212).

If the trigger command of the CSG femto cell discovery of the AMS is received from the paging controller, the HM ABS can transmit an unsolicited ranging response (AAI_RNG-RSP) message to the AMS. Namely, the HM ABS can request the AMS of scanning for CSG femto cell discovery (S1213).

The AMS can perform scanning for CSG femto cell discovery, and can perform location update to the corresponding CSG femto cell if its CSG femto cell is discovered during the scanning process (S1214 ~ S1216).

FIG. 13 is a diagram illustrating another example of a method for accessing a femto cell using a location based service (LBS) in accordance with the embodiment of the present invention.

Since steps S1301 to S1306 of FIG. 13 are the same as the steps S1201 to S1206 of FIG. 12, their description will be replaced with that of FIG. 12. Hereinafter, the part of FIG. 13, which is different from FIG. 12, will be described.

The HM ABS can transmit a paging message (for example, A-PAG-ADV) to a paging listening interval of the AMS. At this time, the HM ABS transmits a paging message of which action codes 0b01 (perform ranging to establish location) and 0b10 (perform LBS measurement) are set to ‘1’, to the AMS (S1307).

In the step S1307, the action code 0b01 indicates to perform ranging to establish location update, and the action code 0b10 indicates the mobile station to measure LBS. In other words, the action code 0b10 set to ‘1’ is only transferred to the AMS which will perform LBS measurement (see Table 10).

The AMS can perform a scanning process for LBS measurement by using location information of a neighboring base station, which is received in the step S1306. The AMS can acquire its location information by using the LBS measurement result (S1308).

The AMS transfers the A-MOB_SCN-REP message, which includes the LBS measurement result (TDOA or TOA, etc.) and/or its location information, to the HM ABS (S1309).

The HM ABS transfers the LBS measurement result received from the AMS, to the paging controller (PC) (S1310).

The paging controller can obtain the location information of the AMS based on the location information of the AMS and/or the LBS measurement result transmitted from the HM ABS. At this time, it is assumed that the paging controller already knows the location information of the CSG femto cell. Accordingly, the paging controller can identify whether the AMS is located at the CSG femto cell surrounding area, by using the location information of the AMS and the location of the CSG femto cell (S1311).

If the paging controller determines that the AMS is located at the CSG femto cell surrounding area, the paging controller can trigger the CSG femto cell discovery process to the HM ABS, whereby the AMS can discover the CSG femto cell (S1312).

If the trigger command of the CSG femto cell discovery of the AMS is received from the paging controller, the HM ABS can transmit an unsolicited ranging response (AAI_RNG-RSP) message to the AMS. Namely, the HM ABS can request the AMS of scanning for CSG femto cell discovery (S1313).

The AMS can perform scanning for CSG femto cell discovery, and can perform location update to the corresponding CSG femto cell if its CSG femto cell is discovered during the scanning process (S1314 ~ S1316).

FIG. 14 is a diagram illustrating still another example of a method for accessing a femto cell using a location based service (LBS) in accordance with the embodiment of the present invention.

Referring to FIG. 14, the mobile station AMS can perform a handover process by moving to the home macro cell where the CSG femto cell is located. Accordingly, the AMS can transmit a handover request (A-MOB_MSHO-REQ) message, which includes context information of the AMS, to a serving base station (serving ABS). At this time, the context information of the AMS can include one or more of MAC address of the AMS, serving base station identifier (S-ABS ID), serving cell identifier (Cell ID), FBS identifier (FBS ID), HMC ID, and HM ABS ID (S1401).

The serving base station can transfer handover associated information to the HM ABS (not shown). Also, the serving base station transmits a handover response (A-MOB_BSHO-RSP) message to the AMS in response to the handover request message (S1402). The AMS transmits a handover indication (A-MOB_MSHO-IND) message to the serving base station to identify and complete handover (S1403).

After the handover process is completely performed, the HM ABS can transfer the context information of the AMS to the ASN-GW (S1404, S1405).

The ASN-GW compares the location information of AMS with the information of the ABS based on the context information transferred from the HM ABS (S1406).

If the AMS moves to the HM ABS where the CSG femto cell is located, the ASN-GW triggers LBS measurement to the HM ABS to indicate the AMS to perform LBS measurement (S1407).

The HM ABS can periodically broadcast A-LBS-ADV message, which includes location information of a neighboring base station, to the AMSs located in its area (S1408).

Also, if the trigger command of the CSG femto cell discovery of the AMS is received from the ASN-GW, the HM ABS can transmit an unsolicited ranging response (A-RNG-RSP) message to the AMS to request the AMS of scanning for CSG femto cell discovery (S1409).

In this case, for the unsolicited A-RNG-RSP message format, refer to Table 3. Accordingly, the HM ABS can set bit #3 of the enabled action triggered TLV parameter to ‘1’ and transmit it to the AMS.

The AMS can perform scanning for LBS measurement by using the location information of the neighboring base station, which is included in the A-LBS-ADV message received from the HM ABS. At this time, since the bit #3 of the enabled action triggered TLV parameter received in the step S1409 is set to ‘1’, the AMS can start the scanning action of the neighboring base station by transmitting the A_SCN-REQ message to the HM ABS. The AMS can acquire its location information through the scanning process (S1410).

In the step S1410, the AMS performs LBS measurement through the scanning process, and acquires the location information of the AMS based on the LBS measurement result. Accordingly, the AMS can transmit the scanning report (A_SCN-REP) message, which includes the LBS measurement result (TDOA or TOA, etc.), to the HM ABS (S1411).

The HM ABS can transfer the location information of the AMS and/or the LBS measurement result, which are received from the AMS, to the ASN-GW (S1412).

The ASN-GW can identify the location information of the AMS based on the LBS measurement result. If the location information of the AMS is directly received from the HM ABS in the step S1402, the ASN-GW can continuously use the location information of the AMS. It is assumed that the ASN-GW already knows the location information of the CSG femto cell. Accordingly, the ASN-GW can determine whether the AMS has entered the surrounding radius R of the CSG femto cell, by using the location information of the AMS and the location information of the CSG femto cell (S1413).

If the ASN-GW determines that the AMS is located at the surrounding radius R of the CSG femto cell, the ASN-GW can trigger CSG femto cell discovery, whereby the AMS can discover the CSG femto cell (S1414).

If the trigger command of the CSG femto cell discovery of the AMS is received from the ASN-GW, the HM ABS can request the AMS of scanning for CSG femto cell discovery by transmitting an unsolicited A-RNG-RSP message to the AMS (S1415).

In this case, for the unsolicited A-RNG-RSP message format, refer to Table 3. Accordingly, the HM ABS can set bit #4 of the enabled action triggered TLV parameter to ‘1’ and transmit it to the AMS. In other words, the HM ABS can command the mobile station to start the CSG femto cell discovery.

The AMS can perform scanning for CSG femto cell discovery based on the parameters received in the step S1415. The AMS can perform handover to the corresponding CSG femto cell if its CSG femto cell is discovered during the scanning process (S1415 ~ S1419).

Method for operating a femto cell of a low duty mode (LDM)

The femto base station (FBS) can be operated at a low duty mode (LDM) for power saving. The low duty mode (LDM) of the femto base station (FBS) includes an available interval (AI) and an unavailable interval (UAI). At the available interval, the femto base station (FBS) can perform action such as system information transmission, ranging, paging or data traffic transmission. At the unavailable interval (UAI), the FBS does not transmit any signal on a wireless interface. However, the FBS may synchronize with the macro base station at the unavailable interval or measure interference from a neighboring base station.

Hereinafter, methods for operating a femto cell at a low duty mode by using location information of a CSG femto cell will be described.

FIG. 15 is a diagram illustrating an example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention.

Referring to FIG. 15, the AMS can move from the current serving base station to the home macro base station (HM ABS) that includes a CSG femto cell of the AMS. At this time, if the AMS is in a normal mode, the AMS performs handover. If the AMS is in an idle mode, which is one of power saving modes, the AMS performs a location update process with the HM ABS.

If the AMS performs handover, the AMS can request the HM ABS of location information of a CSG femto cell to which the AMS has been subscribed, during network entry. At this time, the HM ABS can notify the AMS of location information of the CSG femto cell, wherein the location information includes coordinate information of a local coordinate of the CSG femto base station and radius information R indicating a surrounding radius of the CSG femto cell.

The AMS can perform LBS measurement to periodically acquire its location information. At this time, if it is determined that the AMS has entered the CSG femto cell surrounding area, the AMS can transmit its presence to the HM ABS through several messages. Accordingly, the HM ABS can request the CSG femto cell to shift from the low duty mode to a normal mode. The CSG femto cell requested from the HM ABS can shift the low duty mode to the normal mode. Of course, the AMS may directly request the FBS to shift the low duty mode to the normal mode without through the HM ABS.

FIG. 16 is a diagram illustrating another example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention.

Referring to FIG. 16, the mobile station AMS of the normal mode can move to the home macro cell (HMC) where the CSG femto cell is located, so as to perform a handover process. Accordingly, the AMS can transmit a handover request (A-MOB_MSHO-REQ) message, which includes context information of the AMS, to a serving base station (ABS). At this time, the context information of the AMS can include one or more of MAC address of the AMS, serving base station identifier (S-ABS ID), serving cell identifier (Cell ID), FBS identifier (FBS ID), HMC ID, and HM ABS ID (S1601).

The serving base station can transfer handover associated information to the HM ABS (not shown). Also, the HM ABS can transfer the context information of the AMS to the ASN-GW (S1602).

The serving base station transmits a handover response (A-MOB_BSHO-RSP) message to the AMS in response to the handover request message (S1603). The AMS transmits a handover indication (A-MOB_MSHO-IND) message to the serving base station to identify and complete handover (S1604).

The AMS can completely perform the handover process with the home macro base station (HM ABS) through the steps S1601 to S1604 (S1605).

After performing handover to the HMC, the AMS can perform a network reentry process to the HM ABS (not shown). In this case, the AMS can transmit a ranging request (A-RNG-REQ) message during initial ranging with the HM ABS to request location information of the CSG femto cell, wherein a request of femto cell location information flag of the ranging request mesage is set to ‘1’. The base station can notify the AMS of location information that includes coordinate information and surrounding radius information R of the CSG femto cell. Namely, in FIG. 16, it is assumed that the AMS does not know location information of the FBS.

The HM ABS periodically broadcasts A-LBS-ADV message, which includes location information of a neighboring base station, to mobile stations located within its area. At this time, the location information of the neighboring base station can include local coordinate information of the neighboring base station (S1606).

The AMS can perform a scanning process for location based service (LBS) measurement before performing periodic ranging by using the location information of the neighboring base station, wherein the location information is included in the A-LBS-ADV message received from the base station. The AMS can acquire its location information through the LBS measurement (S1607).

The AMS can determine whether it has entered the CSG femto cell surrounding area, by comparing the location information of the CSG femto cell with the location information of the AMS, which is acquired in the step S1607).

If the AMS enters the CSG femto cell surrounding area, the AMS can notify the MH ABS of its presence. Namely, the AMS can transmit the ranging request message, which includes an indication parameter indicating whether the AMS has entered the CSG femto cell surrounding area, to the HM ABS during periodic ranging. Alternatively, the AMS can periodically transmit a dummy control signal or channel quality information (CQI) report message, which includes the indication parameter, to the HM ABS (S1609).

The HM ABS which has received the indication parameter indicating whether the AMS has entered the CSG femto cell surrounding area from the AMS requests the CSG femto cell of the AMS which is operating at the low duty mode, to shift to the normal mode (S1610).

The femto base station which is operating at the low duty mode can perform the normal action with the AMS by shifting to the normal mode (S1611).

FIG. 17 is a diagram illustrating still another example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention.

In FIG. 17 unlike FIG. 16, if the AMS enters the CSG femto cell surrounding area, the AMS directly performs ranging for the available interval of the CSG femto cell without reporting it to the macro cell, thereby shifting to the normal mode of the CSG femto cell. Since steps S1701 to S1708 of FIG. 17 are the same as the steps S1601 to S1608 of FIG. 16, their description will be replaced with that of FIG. 16. Hereinafter, the part of FIG. 17, which is different from FIG. 16, will be described.

The AMS can identify whether it has entered the CSG femto cell surrounding area, by comparing the location information of the CSG femto cell with the location information of the AMS, which is acquired in the step S1707. If the AMS is located at the CSG femto cell surrounding area, the AMS can transmit the ranging request message, which includes an indication parameter indicating its presence, to the CSG FBS at the available interval (AI) of the CSG FBS of a low duty mode (S1709).

If the ranging request message, which includes the indication parameter, is received from the AMS, the CSG FBS shifts from the low duty mode to the normal mode. Accordingly, the CSG FBS can perform the normal mode action with the AMS (S1710).

FIG. 18 is a diagram illustrating further still another example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention.

In FIG. 18, the AMS is in the idle mode. The AMS of the idle mode can move to the home macro cell (HMC) where the CSG femto cell to which the AMS has been subscribed is located. The AMS of the idle mode can perform a location update process with the HM ABS (S1801).

In this case, the AMS can request the HM ABS of location information of the femto cell to which the AMS has been subscribed during the location update process. Namely, the AMS can transmit the ranging request (A-RNG-REQ) message to the HM ABS, wherein the ranging request message includes a request of femto cell location information flag set to ‘1’ (not shown).

If the request of femto cell location information flag within the A-RNG-REQ message transmitted from the AMS is set to ‘1’, the HM ABS transmits the ranging response, which includes location information of the femto base station, to the AMS, wherein the location information includes coordinate information and radius information of the CSG femto cell (not shown).

Also, the HM ABS periodically broadcasts a location based service advertisement (A-LBS-ADV) message, which includes location information of neighboring base stations, to the AMSs located within its area (S1802).

Furthermore, the HM ABS can transmit a paging message to a paging listening interval of the AMS. At this time, action codes 0b01 and 0b10 of the paging message are set to ‘1’ (see Table 10). In this case, the action code 0b10 can be set to AMS only which perform LBS measurement (S1803).

In the embodiments of the present invention, the step S1803 can be performed selectively. If the step S1803 is performed, the AMS performs action only indicated by the action code of the paging message. Of course, the AMS can perform LBS measurement periodically or at a predetermined interval even in case of no paging message.

The AMS can perform a scanning process for LBS measurement by using the location information of the neighboring base station, which is included in the A-LBS-ADV message received from the HM ABS. The AMS can acquire its location information based on the LBS measurement result (S1804).

The AMS can perform periodic ranging with the femto base station at the paging available interval. At this time, the AMS can notify the HM ABS of the location information of the AMS, which is the LBS measurement result, during the periodic ranging process (S1805).

The AMS can determine whether it has entered the CSG femto cell surrounding area, by comparing the location information of the CSG femto cell with the location information of the AMS, which is acquired in the step S1805 (S1806).

If the AMS enters the CSG femto cell surrounding area, the AMS can notify the MH ABS of its presence. Namely, the AMS can transmit the ranging request message, which includes an indication parameter indicating whether the AMS has entered the CSG femto cell surrounding area, to the HM ABS during periodic ranging with the HM ABS. Alternatively, the AMS can periodically transmit a dummy control signal or channel quality information (CQI) report message, which includes the indication parameter, to the HM ABS (S1807).

The HM ABS which has received the indication parameter indicating whether the AMS has entered the CSG femto cell surrounding area from the AMS requests the CSG femto cell of the AMS which is operating at the low duty mode, to shift to the normal mode (S1808).

The femto base station which is operating at the low duty mode can perform the normal action with the AMS by shifting to the normal mode (S1809).

FIG. 19 is a diagram illustrating further still another example of a method for operating a femto cell at a low duty mode using location information of a CSG femto cell in accordance with the embodiment of the present invention.

In FIG. 19 unlike FIG. 18, if the AMS of the idle mode enters the CSG femto cell surrounding area, the AMS directly performs ranging for the available interval of the CSG femto cell without reporting it to the macro cell, thereby shifting to the normal mode of the CSG femto cell. Since steps S1901 to S1906 of FIG. 19 are the same as the steps S1801 to S1806 of FIG. 18, their description will be replaced with that of FIG. 18. Hereinafter, the part of FIG. 19, which is different from FIG. 18, will be described.

In step S1906, the AMS can identify whether it has entered the CSG femto cell surrounding area, by comparing the location information of the CSG femto cell with the location information of the AMS, which is acquired in the step S1905. If the AMS is located at the CSG femto cell surrounding area, the AMS can transmit the ranging request message, which includes an indication parameter indicating its presence, to the CSG FBS at the available interval (AI) of the CSG FBS of a low duty mode (S1907).

If the ranging request message, which includes the indication parameter, is received from the AMS, the CSG FBS shifts from the low duty mode to the normal mode. Accordingly, the CSG FBS can perform the normal mode action with the AMS (S1908).

The mobile station is operated as a transmitter in an uplink, whereas the mobile station is operated as a receiver in a downlink. Also, the base station is operated as a receiver in the uplink, whereas the base station is operated as a transmitter in the downlink.

In other words, each of the mobile station and the base station can include a

Tx module

2040, 2050 and a

RX module

2050, 2070 to control transmission and reception of information, data and/or message. Also, each of the mobile station and the base station can include an

antenna

2000, 2010 for transmitting and receiving information, data and/or message. Moreover, each of the mobile station and the base station can include a

processor

2020, 2030 for performing the aforementioned embodiments of the present invention and a

memory

2080, 2090 for temporarily or continuously storing a process of the processor.

In particular, the

processor

2020, 2030 can further include a handover module for performing a handover process disclosed in the embodiments of the present invention, an encoding module (or means) for encoding signal or message to be transmitted, and/or a decoding module (or means) for decoding the encoded message. Also, each of the mobile station and the base station of FIG. 20 can further include a low power radio frequency (RF)/intermediate frequency (IF) module.

The Tx module and the Rx module included in the mobile station and the base station can perform packet modulation and demodulation function for data transmission, quick packet channel coding, orthogonal frequency division multiple access (OFDMA) packet scheduling, time division duplex (TDD) packet scheduling and/or channel multiplexing function.

Furthermore, the processor included in the mobile station and the base station can perform a control function for performing the aforementioned embodiments of the present invention, a handover function, an authentication and encryption function, a medium access control (MAC) frame variable control function according to service characteristics and radio wave condition, a quick traffic real-time control function, and/or a real-time modem control.

The modules described in FIG. 20 are means through which the methods described in FIG. 2 to FIG. 19 can be carried out. The embodiments of the present invention can be carried out by using the modules and functions of the aforementioned mobile station and base station.

The processor 2020 provided in the mobile station can include a handover module that can control handover action, a power saving module for performing an idle mode action, and a scanning module for measuring the status of a radio channel.

The mobile station can control the aforementioned handover action, ranging action, scanning action, idle mode action, and/or determination as to entry to femto cell radius area by using the processor, and can transmit and receive the messages used for the above actions by using the Tx module and the Rx module.

The modules of the base station, which are described in FIG. 20, can be used as those of the femto base station as well as the macro base station. If the modules of the base station described in FIG. 20 are used for the femto base station, the processor 2030 can control the low duty mode (LDM) action of the femto base station.

Also, in the embodiments of the present invention, the paging controller (PC) and/or the access service network gateway (ASN-GW) is an upper entity of the base station and can carry out the embodiments of the present invention. In other words, the PC and/or the ASN-GW can be operated as an inner upper entity or an outer upper entity.

In the embodiments of the present invention, the mobile station and the base station can carry out the methods described in FIG. 2 to FIG. 19 by using the modules disclosed in FIG. 20. In order to transmit and receive messages, the Tx module and the Rx module are used. The respective steps and actions can be controlled by the controller of the mobile station and the base station.

Meanwhile, in the present invention, examples of the mobile station include a personal digital assistant (PDA), a cellular phone, a personal communication service (PCS) phone, a global system for mobile (GSM) phone, a wideband CDMA (WCDMA) phone, a mobile broadband system (MBS) phone, a hand-held PC, a notebook PC, a smart phone, and a multi mode-multi band (MM-MB) terminal.

In this case, the smart phone is a terminal provided with advantages of a mobile communication terminal and a PDA. The smart phone may mean a terminal in which a schedule management function of a PDA and data communication functions of facsimile transmission/reception, internet access, etc. are integrated on a mobile communication terminal. And, the multimode-multiband terminal means a terminal having a built-in multi-MODEM chip to be operable in a portable internet system and other mobile communication systems (e.g., CDMA (code division multiple access) 2000 system, WCDMA (wideband CDMA) system, etc.).

The embodiments according to the present invention can be implemented by various means, for example, hardware, firmware, software, or their combination. If the embodiment according to the present invention is implemented by hardware, the embodiment of the present invention may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

If the embodiment according to the present invention is implemented by firmware or software, the method of transmitting and receiving data in the wireless communication system according to the embodiment of the present invention may be implemented by a type of a module, a procedure, or a function, which performs functions or operations described as above. For example, a software code may be stored in a

memory unit

2080, 2090 and then may be driven by a

processor

2020, 2030. The memory unit may be located inside or outside the processor to transmit and receive data to and from the processor through various means which are well known.

It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential characteristics of the invention. Thus, the above embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the invention should be determined by reasonable interpretation of the appended claims and all change which comes within the equivalent scope of the invention are included in the scope of the invention.

The present invention can be applied to various wireless access systems. Examples of the various wireless access systems include 3GPP(3rd Generation Partnership Project) system, 3GPP2 system and/or IEEE 802.xx (Institute of Electrical and Electronic Engineers 802) system. The embodiments of the present invention can be applied to all technical fields to which the various access systems are applied, as well as the various access systems.

Claims

A method for accessing a femto cell using a location based service (LBS), the method comprising:

transmitting a first message to a macro base station, the first message including a flag requesting location information of the femto cell;

receiving a second message from the macro base station, the second message including the location information of the femto cell;

receiving a third message from the macro base station, the third message including location information of a neighboring base station;

performing the LBS measurement using the location information of the neighboring base station; and

accessing the femto cell using the result of the LBS measurement and the location information of the femto cell.
The method of claim 1, wherein the location information of the femto cell includes local coordinate information of the femto cell and radius information R of a surrounding radius of the femto cell.
The method of claim 2, wherein the first message is one of a ranging request message, a registration request message, and a basic capability negotiation request message, and the second message is one of a ranging response message, a registration response message, and a basic capability negotiation response message.
The method of claim 2, wherein the third message is either a neighboring base station advertisement message or a location based service advertisement message.
The method of claim 1, further comprising transmitting the result of the location based service measurement to the base station.
The method of claim 5, further receiving a fourth message from the base station, the fourth message indicating access to the femto cell.
The method of claim 1, further comprising transmitting a message to the base station, the message including an indicator indicating that the mobile station is located at a radius area of the femto cell.
The method of claim 1, further comprising transmitting a message to the femto cell, the message including an indicator indicating that the mobile station is located at a radius area of the femto cell.
The method of claim 1, wherein the location based service measurement is performed in accordance with a measurement manner such as round trip delay time measurement, U-TDOA, D-TDOA or TOA.
A mobile station supporting a method for accessing a femto cell using a location based service (LBS), the mobile station comprising:

a Tx module transmitting a radio signal;

a Rx module receiving a radio signal; and

a processor controlling the method for accessing a femto cell using a location based service,

wherein the processor controls the steps of:

transmitting a first message to a macro base station using the Tx module, the first message including a flag requesting location information of the femto cell;

receiving a second message from the macro base station using the Rx module, the second message including the location information of the femto cell;

receiving a third message from the macro base station using the Rx module, the third message including location information of a neighboring base station;

performing the LBS measurement using the location information of the neighboring base station; and

accessing the femto cell using the result of the LBS measurement and the location information of the femto cell.
The mobile station of claim 10, wherein the location information of the femto cell includes local coordinate information of the femto cell and radius information R of a surrounding radius of the femto cell.
The mobile station of claim 11, wherein the first message is one of a ranging request message, a registration request message, and a basic capability negotiation request message, and the second message is one of a ranging response message, a registration response message, and a basic capability negotiation response message.
The mobile station of claim 12, wherein the third message is either a neighboring base station advertisement message or a location based service advertisement message.
The mobile station of claim 11, wherein the mobile station further performs the steps of transmitting the result of the location based service measurement to the base station; and receiving a fourth message from the base station, the fourth message indicating access to the femto cell.
The mobile station of claim 11, wherein the mobile station further performs the step of transmitting a message to the base station or the femto cell, the message including an indicator indicating that the mobile station is located at a radius area of the femto cell.