Abstract:
A Femto base station ( 102 ), multimedia gateway ( 101 ), user equipment ( 113 ), IMS application server ( 121 ) and control method thereof are provided to enable a communication between a user equipment and the multimedia gateway via IP Multimedia Subsystem network. The multimedia gateway comprises first receiving means ( 307 ) for receiving cell information relates to a cell generated by said Femto base station from said Femto base station, generation means ( 306 ) for generating an identification information uniquely associating said multimedia gateway with a user equipment connected to the cell generated by the Femto base station and transmitting means for transmitting a SIP message with the identification information to a IMS application server in IMS network.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a Femto base station, multimedia gateway, user equipment, IMS application server and control method thereof enabling a communication between a user equipment and the multimedia gateway via an IMS (IP Multimedia Subsystem) network. 
       BACKGROUND 
       [0002]    A network architecture called IMS has been developed by the 3rd Generation Partnership Project (3GPP) as an open standard for handling multimedia services and sessions in the packet domain. Various communication terminals and devices, hereinafter referred to as IMS terminals, that conform to the IMS standard are now known. A typical example of an IMS terminal is a mobile phone with IMS functionality. A personal computer (PC), a personal digital assistant (PDA), or the like can also serve as IMS terminals if they are equipped with IMS functionality. IMS terminals can provide multimedia services by, for example, receiving video streaming from a video-streaming server over an IMS network. 
         [0003]    However, many communication terminals, hereinafter referred to as non-IMS terminals, still exist which are not IMS-enabled, i.e. that do not have IMS functionality). International Publication No. WO 2006/045706 discloses a multimedia gateway called a “Home IMS Gateway” (HIGA), enabling these non-IMS terminals which do not have IMS functionality such as a desktop PC, a laptop PC, and PSTN (Public Switched Telephone Network) connected phones including DECT to access services via the IMS network. 
         [0004]    According to WO 2006/045706, the HIGA is located in a private network, to which at least one non-IMS terminal is connected. The HIGA includes a Session Initiation Protocol (SIP) Back-to-Back User Agent (B2BUA) for facilitating communication between non-IMS terminals and the IMS network. The HIGA also includes a SIP gateway implemented according to 3GPP TS 24.229 and IETF RFC 3261. The SIP gateway allows inter-operation between various client terminal signaling protocols and the SIP used by the IMS. For example, the SIP gateway may provide translation between ISDN-based signaling protocols and the SIP. Accordingly, the non-IMS terminals may or may not have SIP functionality. HIGA can be implemented on a “Set Top Box” (STB), a “Residential Gateway” (RGw) and different home devices. HIGA may be used to deliver, via the IMS network, home content, including home movies or pictures of a user&#39;s family stored in a Desktop PC connected thereto, to a TV to be used to display delivered content and being located at an external area, for example, a friend&#39;s home which the user visits or a hotel room where the user stays. Control of the delivered contents like trick play may be carried out by the user&#39;s mobile phone (i.e. 3-box model). 
         [0005]    Recently, a home/residential base station called a “Femto base station (Femto-BS)” is proposed as a solution to the problem regarding a limited power reception level of the mobile phone especially in remote areas located far from an ordinary base station and in residences. The Femto-BS provides in-home mobility with maximum user data rates without loading macro node cell sites. 
         [0006]    The Femto-BS may be collocated with the HIGA to provide a mobile communication service using user equipments (UE). 
         [0007]      FIG. 1A  shows a situation where the HIGA and Femto-BS are implemented in a single device called “Femto Customer Premises Equipment (Femto-CPE)”. 
         [0008]    In  FIG. 1A , there is a Femto CPE  100  which includes a HIGA  101  and a Femto-BS  102  in a user&#39;s residence  10 . The HIGA  101  provides an IMS connection service to client devices  111  and  112 . The client devices include client apparatuses with or without IMS functionality. The Femto-BS is a base station to generate a Femto-Cell/Access Point Base station inside the residence  10  and to provide the UE located in the Femto-Cell with an access to a mobile communication network via an RNC (Radio Network Controller)  131  and a SGSN/GGSN(Serving GPRS Support Node/Gateway GPRS Support Node)  132 . A UE is a user terminal to communicate with other UEs over the radio communication link according to a radio communication protocol such as ANSI-136, GSM (Global Standard for Mobile) communication, GPRS (General Packet Radio Service), EDGE (Enhanced Data Rates for GSM Evolution), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA), CDMA2000, Long Term Evolution (LTE) and UMTS (Universal Mobile Telecommunications System). The UE may be a mobile phone which can communicate over the mobile communications network. The RNC  131  is connected over a Broadband Access Network  140  to the Femto-BS  102 . The SGSN/GGSN  132  connects and communicates data packet and control signals with the RNC  131 . 
         [0009]    IMS network  120  includes an IMS application server (AS)  121  and a Call Session Control Function (CSCF)  122 . The CSCF  122  is a SIP server controlling sessions established between terminals in SIP communication and accessing the AS  121  to initiate certain services. The CSCF  122  is connected over the Broadband Access Network  140  to the HIGA  101 . The CSCF  122  may include a Proxy CSCF (P-CSCF), an Interrogating CSCF (I-CSCF) and a Serving CSCF (S-CSCF). The AS  121  is a server which provides various applications to the Client Devices  111  and  112 . 
         [0010]    When considering the usage described in  FIG. 1A , local connectivity between the HIGA  101  and the UE  113  may be established using a wireless communication functionality, for example based on any protocol of IEEE802.11a/b/g/n (WiFi), IEEE802.15 (Bluetooth), IEEE802.16 (WiMax) or IrDA (Infrared Data Association). If the UE  113  connects to the HIGA  101 , it may be able to control the client devices  111  and  112  also connected to the HIGA  101  according to, for example, the UPnP and SIP protocols. 
         [0011]    However, there will be a situation in which any one of the UE  113  and the HIGA  101  does not have such an IP based wireless communication functionality, for example, the UE does not have WiFi functionality or the HIGA  101  does not have Bluetooth and IrDA functionalities. Many UE  113  in the form of a mobile phone do no not have WiFi functionality. In such cases, the UE  113  can not access the HIGA  101  and the HIGA  101  can not recognize the existence of the UE  113 . 
         [0012]    Accordingly, it is necessary to provide a technique which enables the HIGA  101  to recognize the existence of the UE  113  without using IP based wireless communication functionality between the HIGA  101  and UE  113 . 
         [0013]    One solution to solve this problem is, as is depicted in  FIG. 1B , to provide the Femto-BS  102  with a part of RNC and SGSN/GGSN functionalities  201  to extract packet data transmitted from the UE  113  over mobile radio access network. In this case, the HIGA  101  can intercept IMS messages sent and received by the UE  113  and thus they are able to know each other and communicate. However, this type of installation increases the complexity of the Femto-CPE  100  and its cost relative to the installation type depicted in  FIG. 1A . 
         [0014]    Thus, the present invention is intended to address the above-described problem without increasing the complexity of the Femto-CPE  100 . 
         [0015]    Further, if the UE  113  has IP based wireless communication functionality, there is a case in which the HIGA also cannot recognize the existence of the UE  113 , as follows. 
         [0016]    Generally, IEEE 802.11 Wireless LAN Access Point (WLAN-AP) can serve two or more Wireless Local Area Networks (WLANs). Each WLAN is identified by Service Set Identifier (SSID) and can have different security settings. This SSID is broadcast by the WLAN-AP so that the client can present the list of WLANs to the user in order for the user to select one of them, or the client can connect to one of the WLANs if the SSID and its associated security settings are pre-configured. 
         [0017]    There are different methods for authenticating and authorizing a WLAN user and encrypting data transmitted over the WLAN, such as WEP (Wired Equivalent Privacy) and WPA (WiFi Protected Access). A user connected to a WLAN identified by an SSID cannot access another WLAN network identified by another SSID if their security settings are different. 
         [0018]    FON (http://www.fon.com) is a public WLAN-AP service wherein a participant of the FON community opens their WLAN-AP to let the others access the Internet via the WLAN-AP. FON WLAN-AP serves two WLANs distinguished by different SSID; one of them is accessible only by home users who have knowledge of the security settings; the other is open for public use. 
         [0019]    3GPP TS 23.234 and TS 33.234 define requirements necessary for interworking between WLAN and telecom network.  FIG. 2  depicts a deployment scenario wherein WLAN-AP  103  is placed in a room such as a hotel room. In  FIG. 2 , the similar reference numerals are used for corresponding units depicted in  FIG. 1A . 
         [0020]    In  FIG. 2 , the WLAN-AP  103  serves two different WLANs (WLAN  1  ( 104 ) and WLAN  2  ( 105 )) distinguished by SSID. WLAN  1  ( 104 ) is accessible only by devices to which an operator such as a hotel staff member preconfigures a private key. WLAN  2  ( 105 ) is made public with a relaxed security setting so that a hotel guest may access it with their own PC, mobile phone or the like. In this situation, the UE  113  cannot directly access a client device  111  such as a TV connected to WLAN  1  ( 104 ) and HIGA  101 , because of different security settings. 
         [0021]    Data transmitted on the WLAN  1  ( 104 ) can be protected using WEP for example. In the WLAN  1  ( 104 ), the private key is generated and set to devices including HIGA  101  and client devices  111  and  112  connected to the WLAN  1  ( 104 ). The key is input to Pseudo-Random Number Generator (PRNG) after a 24 bit Initialization Vector (IV) is attached to the key. The data transmitted over WLAN  1  ( 104 ) is encrypted by an XOR operation with the random number generated by the PRNG. The encrypted data is transmitted with the IV. The receiver uses the private key and the IV to decrypt the received data. 
         [0022]    The private key is never transmitted over the WLAN  1  ( 104 ) and thus only devices where the private key is respectively preconfigured can communicate with each other over the WLAN  1  ( 104 ). 
         [0023]    The UE  113  cannot access the WLAN  1  ( 104 ) but can access the WLAN  2  ( 105 ), because the security settings such as SSID and the private key for the WLAN  2  ( 105 ) are shared by a plurality of users of the WLAN  2  ( 105 ). After connecting to the WLAN  2  ( 105 ), the UE  113  communicates with 3GPP AAA/HSS (Authentication, Authorization and Accounting/Home Subscriber Server)  135  of the telecom operator in order to establish a secure connection to the Internet using the interworking defined by 3GPP. 3GPP AAA/HSS  135  authenticates and authorizes the UE  113  based on the shared secret stored in its ISIM or USIM. 
         [0024]    If the authentication is successfully completed, an IP address is assigned to the UE  113  and the UE  113  can transmit data encrypted using a key assigned to the UE  113  to a Packet Data Gateway (PDG)  134 . The PDG  134  can decode the received data from the UE  113  and forward the decoded data to the CSCF  122 . Thus, a secure IP tunnel  141  is established between the PDG  134  and the UE  113  so that no other users can read the transmitted data. 
         [0025]    Accordingly, in the situation of  FIG. 2 , WLAN-AP  103  cannot provide direct communication between the HIGA  101  and the UE  113 . Thus, the UE  113  cannot access the HIGA  101  and the HIGA  101  cannot recognize the existence of the UE  113 . 
         [0026]    Thus, the present invention is intended to provide techniques for enabling the HIGA  101  to recognize the existence of the UE  113  and allow the UE  113  to communicate with the HIGA  101  via the IMS network  120  without introducing major alteration of the physical structure of the communication system. 
       SUMMARY 
       [0027]    According to a first aspect of the invention, there is provided a Femto base station adapted to generate a cell and communicate with a multimedia gateway having a IMS gateway functionality and a device detection functionality (for connecting a user equipment/client device connectable to the multimedia gateway). The Femto base station comprises receiving means for receiving cell information related to a cell generated by said Femto base station from a radio network controller, first transmitting means for transmitting the cell information to said multimedia gateway, and second transmitting means for transmitting the cell information to a user equipment connected to the cell. In some embodiments, the cell information comprises Mobile Country Code, Mobile Network code, UMTS Cell Identity and Local Area Code. 
         [0028]    According to a second aspect of the invention, there is provided a multimedia gateway, e.g. positioned in a Local Area Network such as a residential network, which has an IMS gateway functionality and a device detection functionality connected thereto and is adapted to communicate with a Femto base station adapted to generate a cell. The multimedia gateway comprises first receiving means for receiving cell information related to the cell from said Femto base station, generation means for generating an identification information uniquely associating said multimedia gateway with a user equipment connected to the Femto base station via the cell, using the received cell information, and transmitting means for transmitting a SIP message with the identification information to an IMS application server via an IMS network. 
         [0029]    According to a third aspect of the invention, there is provided a multimedia gateway which has an IMS gateway functionality and a device detection functionality and is adapted to communicate with a wireless local area network access point adapted to generate a first wireless local area network for said multimedia gateway and a second wireless local area network for a user equipment. The multimedia gateway comprises first receiving means for receiving from said wireless local area network access point of information used to uniquely identify said wireless local area network access point via the first wireless local area network, generation means for generating an identification information uniquely associating said multimedia gateway with the user equipment using the received information, and transmitting means for transmitting a SIP message with the identification information to an IMS application server via an IMS network. 
         [0030]    In some embodiments, the identification information is P-Access-Network-Info to be attached in a header portion of the SIP message. 
         [0031]    In some embodiments, the SIP message transmitted by said transmitting means of said multimedia gateway is a SUBSCRIBE message. 
         [0032]    In some embodiments, the SIP message transmitted by said transmitting means of said multimedia gateway is a PUBLISH message with control information to control a client device connected to said multimedia gateway. 
         [0033]    In some embodiments, the multimedia gateway further comprises second receiving means for receiving a SIP message notifying presence information regarding the user equipment. 
         [0034]    In some embodiments, the multimedia gateway further comprises second receiving means for receiving a SIP message notifying a contact address of the user equipment. 
         [0035]    According to a fourth aspect of the invention, there is provided a user equipment adapted to be connected to a Femto base station adapted to generate a cell and communicate with a multimedia gateway having a IMS gateway functionality and a device detection functionality. The user equipment comprises receiving means for receiving cell information related to the cell from said Femto base station, generation means for generating an identification information uniquely associating said multimedia gateway with said user equipment using the received cell information, and transmitting means for transmitting a SIP message with the identification information to an IMS application server via an IMS network. 
         [0036]    According to a fifth aspect of the invention, there is provided a user equipment to be connected to a wireless local area network access point adapted to generate a first wireless local area network for a multimedia gateway having a IMS gateway functionality and a device detection functionality and a second wireless local area network for said user equipment. Said user equipment comprises receiving means for receiving information used to uniquely identify the wireless local area network access point via the second wireless local area network, generation means for generating an identification information uniquely associating said multimedia gateway with said user equipment using the received information, and transmitting means for transmitting a SIP message with the identification information to a IMS application server via an IMS network. 
         [0037]    In some embodiments, the identification information is P-Access-Network-Info to be attached in a header portion of the SIP message. 
         [0038]    In some embodiments, the SIP message transmitted by the transmitting means of the user equipment is a SUBSCRIBE message. 
         [0039]    In some embodiments, the SIP message transmitted by the transmitting means of the user equipment is a PUBLISH message with presence information regarding said user equipment. 
         [0040]    In some embodiments, the receiving means of the user equipment further receives a SIP message notifying control information to control a client device connected to said multimedia gateway. 
         [0041]    In some embodiments, the receiving means of the user equipment further receives a SIP message notifying a contact address of the multimedia gateway. 
         [0042]    According to a sixth aspect of the invention, there is provided an IMS application server adapted to be connected to an IMS network, and adapted to communicate with a multimedia gateway having a IMS gateway functionality and a device detection functionality and to a user equipment adapted to be connected to a Femto base station or a wireless local area network access point adapted to communicate with the multimedia gateway. The IMS application server comprises first receiving means for receiving a first SIP message transmitted from the multimedia gateway or the user equipment, wherein the first SIP message including identification information uniquely associating the multimedia gateway with the user equipment, storage means for storing a list of the received identification information associated with the originating SIP URI (Uniform Resource Identifier) of the first SIP message, searching means for searching the list for a group of SIP URIs having the same identification information, and transmitting means for transmitting a second SIP message destined to each of SIP URIs in the searched group with another SIP URI paired with the destination SIP URI. 
         [0043]    In some embodiments, the IMS application server further comprises second receiving means for receiving a third SIP message with the identification information and an attachment from the multimedia gateway or the user equipment, wherein said searching means further searches the same identification information included in the list as the identification information received by the second SIP message, and said transmitting means further transmits the attachment received by the third SIP message to a destination associated with the searched identification information. 
         [0044]    In some embodiments, the identification information is P-Access-Network-Info to be attached in a header portion of the SIP message. 
         [0045]    In some embodiments, the attachment is presence information of the user equipment. 
         [0046]    In some embodiments, the attachment is control information to control a client device connected to the multimedia gateway. 
         [0047]    According to a seventh aspect of the invention, there is provided a IMS application server adapted to be connected to an IMS network and adapted to communicate with a multimedia gateway having a IMS gateway functionality and a device detection functionality and a user equipment adapted to be connected to a Femto base station or a wireless local area network access point adapted to communicate with the multimedia gateway. The IMS application server comprises transmitting means for transmitting a first SIP message requesting a notification to the IMS application server of an occurrence of a change in a registration status regarding the multimedia gateway or the user equipment, to a Call Session Control Function server, receiving means for receiving a second SIP message notifying SIP URI and identification information of the multimedia gateway or the user equipment whose registration status has changed, wherein the identification information uniquely associates the multimedia gateway with the user equipment, storage means for storing a list of the SIP URI and identification information received by the second SIP message in association with each other, searching means for searching SIP URIs associated with the same identification information for the list, and transmitting means for transmitting a SIP message notifying one of the searched SIP URIs to a destination corresponding to another searched SIP URI. 
         [0048]    According to an eighth aspect of the invention, there is provided a method of controlling a Femto base station adapted to generate a cell and communicate with a multimedia gateway having an IMS gateway functionality and a device detection functionality. The method comprises the steps of: receiving cell information related to the cell generated by said Femto base station from a radio network controller, transmitting the cell information to said multimedia gateway, and transmitting the cell information to a user equipment connected to the cell. 
         [0049]    According to a ninth aspect of the invention, there is provided a method of controlling a multimedia gateway which has an IMS gateway functionality and a device detection functionality connected thereto and is adapted to communicate with a Femto base station adapted to generate a cell. The method comprises the steps of: receiving cell information related to the cell from said Femto base station, generating an identification information uniquely associating said multimedia gateway with a user equipment connected to the Femto base station via the cell, using the received cell information, and transmitting a SIP message with the identification information to a IMS application server via an IMS network. 
         [0050]    According to an tenth aspect of the invention, there is provided a method of controlling a multimedia gateway which has an IMS gateway functionality and a device detection functionality and is adapted to communicate with a wireless local area network access point adapted to generate a first wireless local area network for said multimedia gateway and a second wireless local area network for a user equipment. The method comprises the steps of: receiving from said wireless local area network access point of information used to uniquely identify said wireless local area network access point via the first wireless local area network, generating an identification information uniquely associating said multimedia gateway with the user equipment using the received information, and transmitting a SIP message with the identification information ( 500 ) to an IMS application server via an IMS network. 
         [0051]    In some embodiments, the method further comprises the step of receiving a SIP message notifying presence information regarding a user equipment. 
         [0052]    In some embodiments, the method further comprises the step of receiving a SIP message notifying a contact address of a user equipment. 
         [0053]    According to an eleventh aspect of the invention, there is provided a method of controlling a user equipment adapted to be connected to a Femto base station adapted to generate a cell and communicate with a multimedia gateway having a IMS gateway functionality and a device detection functionality. The method comprises the steps of: receiving cell information related to the cell from said Femto base station, generating an identification information uniquely associating said multimedia gateway with said user equipment using the received cell information, and transmitting a SIP message with the identification information to a IMS application server via an IMS network. 
         [0054]    According to a twelfth aspect of the invention, there is provided a method of controlling a user equipment to be connected to a wireless local area network access point adapted to generate a first wireless local area network for a multimedia gateway having a IMS gateway functionality and a device detection functionality and a second wireless local area network for said user equipment. The method comprises the steps of: receiving information used to uniquely identify the wireless local area network access point via the second wireless local area network, generating an identification information uniquely associating said multimedia gateway with said user equipment, using the received information, and transmitting a SIP message with the identification information to a IMS application server via an IMS network. 
         [0055]    In some embodiments, the method of controlling the user equipment further comprises the step of receiving a SIP message notifying control information to control a client device connected to said multimedia gateway. 
         [0056]    In some embodiments, the method of controlling the user equipment further comprises the step of receiving a SIP message notifying a contact address of the multimedia gateway. 
         [0057]    According to a thirteenth aspect of the invention, there is provided a method of controlling a IMS application server adapted to be connected to an IMS network and adapted to communicate with a multimedia gateway having a IMS gateway functionality and a device detection functionality and a user equipment adapted to be connected to a Femto base station or a wireless local area network access point ( 103 ) adapted to communicate with the multimedia gateway. The method comprises the steps of receiving a first SIP message transmitted from the multimedia gateway or the user equipment, wherein the SIP message includes identification information uniquely associating the multimedia gateway with the user equipment, storing a list of the received identification information associated with the originating SIP URI of the first SIP message, searching the list for a group of SIP URIs having the same identification information, and transmitting a second SIP message destined to each of SIP URIs in the searched group with another SIP URI paired with the destination SIP URI. 
         [0058]    In some embodiments, the method of controlling a IMS application server further comprises the steps of: receiving a third SIP message with the identification information and an attachment from the multimedia gateway or the user equipment, searching the same identification information included in the list as the identification information received by the second SIP message, and transmitting the attachment received by the third SIP message to a destination associated with the searched identification information. 
         [0059]    According to a fourteenth aspect of the invention, there is provided a method of controlling an IMS application server connected to an IMS network, and adapted to communicate with a multimedia gateway having a IMS gateway functionality and a device detection functionality and a user equipment adapted to be connected to a Femto base station or a wireless local area network access point adapted to communicate with the multimedia gateway. The method comprises the steps of transmitting a first SIP message requesting a notification to the IMS application server of an occurrence of a change in a registration status regarding the multimedia gateway or the user equipment, to a Call Session Control Function server, receiving a second SIP message notifying SIP URI and identification information of the multimedia gateway or the user equipment whose registration status has changed, wherein the identification information uniquely associates the multimedia gateway with the user equipment, storing a list of the SIP URI and identification information received by the second SIP message in association with each other, searching SIP URIs associated with the same identification information for the list, and transmitting a SIP message notifying one of the searched SIP URIs to a destination corresponding to another searched SIP URI. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0060]      FIG. 1A  shows a situation where the HIGA and Femto-BS are implemented into one device called “Femto Customer Premises Equipment (Femto-CPE)” according to an embodiment of the invention; 
           [0061]      FIG. 1B  shows a situation where the HIGA and Femto-BS are implemented into Femto-CPE and the Femto-BS includes a part of RNC and SGSN/GGSN functionalities; 
           [0062]      FIG. 2  shows a situation where the HIGA uses one wireless LAN and the UE uses another wireless LAN; 
           [0063]      FIG. 3A  illustrates an exemplary Femto-CPE  100  according to an embodiment of the invention; 
           [0064]      FIG. 3B  illustrates an exemplary user equipment (UE)  113  according to an embodiment of the invention; 
           [0065]      FIG. 3C  illustrates an exemplary IMS network  120  according to an embodiment of the invention; 
           [0066]      FIG. 3D  illustrates an exemplary HIGA  101  and WLAN-AP  103  according to an embodiment of the invention; 
           [0067]      FIG. 4  only illustrates one example of installation of Femto-CPE  100  according to the invention; 
           [0068]      FIG. 5  illustrates an example of P-Access-Network-Info according to an embodiment of the invention; 
           [0069]      FIG. 6  illustrates an exemplary procedure to generate P-Access-Network-Info in the UE  113  according to an embodiment of the invention; 
           [0070]      FIG. 7  shows an exemplary sequence diagram illustrating a procedure where the HIGA  101  is started (or restarted) and finds the UE  113  which newly enters the Femto Cell generated by the Femto-BS  102 ; 
           [0071]      FIG. 8  shows an example of a list according to an embodiment of the invention. 
           [0072]      FIG. 9  shows another exemplary sequence diagram illustrating a procedure where the HIGA  101  finds the UE  113  which newly enters the Femto Cell generated by the Femto-BS  102 ; 
           [0073]      FIG. 10  shows an example of a notification list according to an embodiment of the invention; 
           [0074]      FIG. 11  shows an example of “Registration information document # 1 ” according to the embodiment; 
           [0075]      FIG. 12  shows further exemplary sequence diagram illustrating a procedure where the HIGA  101  finds the UE  113  which newly enters the Femto Cell generated by the Femto-BS  102 ; 
           [0076]      FIG. 13  shows an example of a presence table  1300  according to an embodiment of the invention; 
           [0077]      FIG. 14  shows an example of presence information of the HIGA  101  stored in presence table  1300  according to an embodiment of the invention; 
           [0078]      FIG. 15  shows an example of presence information of the UE  111  stored in presence table  1300  according to an embodiment of the invention; 
           [0079]      FIG. 16  shows exemplary sequence diagram illustrating a procedure where the HIGA  101  is started (or restarted) and finds the UE  113  which newly connects to the WLAN  2  generated by the WLAN-AP  103 . 
       
    
    
     DETAILED DESCRIPTION 
       [0080]    Embodiments of the invention will now be described with reference to the attached drawings. Each embodiment described below will be helpful in understanding a variety of concepts from the generic to the more specific. 
         [0081]    It should be noted that the technical scope of the present invention is defined by claims, and is not limited by each embodiment described below. In addition, not all combinations of the features described in the embodiments are always indispensable for the present invention. 
         [0082]    Installation of HIGA  101  and Femto-BS  102  in an indoor situation according to the embodiments of the present invention is the same as the one depicted in  FIG. 1A . 
         [0083]      FIG. 3A  illustrates an exemplary Femto-CPE  100  according to the embodiment of the present invention. The exemplary Femto-CPE  100  includes the HIGA  101  and Femto-BS  102 . 
         [0084]    The HIGA  101  includes at least IMS Subscriber Identity Module applications (ISIM)  301 , Device DB  302 , SIP UA/UA Proxy Unit  303 , B2BUA  304 , communication I/F  305 , and a control and processing unit  306 . 
         [0085]    ISIM  301  stores a single IMS Private Identity (IMPI) and at least one of possibly multiple IMS Public Identities (IMPUs). One of the IMPUs may be allocated to Femto-BS  102  to make it easier for HIGA  101  to route incoming IMS messages. 
         [0086]    Device DB  302  stores a list of client devices  111  and  112  including a control URI for each device. The control URI may be obtained from the client device in UPnP discovery procedure and stored in the Device DB  302 . 
         [0087]    The SIP UA/UA Proxy Unit  303  connects Non-SIP client devices which do not have the IMS functionality to IMS network  120  by converting the communication protocol of the Non-SIP client device (for example, HTTP) to SIP protocol. The B2BUA  304  connects the SIP client devices which do not have the IMS functionality to IMS network  120 . The communication I/F  305  is an interface for communicating with the Femto-BS  102 . 
         [0088]    The control and processing unit  306  controls operation of the HIGA  101  including SIP message generation and UPnP device discovery function. The control and processing unit  306  is connected to Broadband Access Network  140  which in turn is connected to CSCF  122  to transmit and receive information including SIP message. The Femto-BS  102  includes at least a communication I/F  311 , a control and processing unit  312  and a transceiver  313 . The communication I/F  311  is an interface to communicate with the HIGA  101 . The control and processing unit  312  which controls the overall processing in the Femto-BS  102  and is connected to Broadband Access Network  140  which in turn is connected to RNC  131 . Femto-BS  102  also includes a transceiver  313  which handles packet traffic channels and control channels and is controlled by the control and processing unit  312 . The transceiver  313  transmits and receives information over traffic channels or control channels to and from the UE  113  using an antenna  314 .  FIG. 3B  illustrates an exemplary user equipment (UE)  113  according to the embodiment of the present invention. The exemplary UE  113  includes a transceiver  321  and a processing unit  322 . The transceiver  321  transmits and receives information including SIP messages over traffic channels or control channels to and from the Femto-BS  102 . The processing unit  322  executes processing necessary for communication via Femto-BS  102 . The processing unit  322  generates SIP message and P-Access-Network-Info based on the cell information received from the Femto-BS  102  according to the embodiments of the present invention. 
         [0089]      FIG. 3C  illustrates an exemplary IMS network  120  according to the embodiment of the present invention. IMS network  120  includes the IMS application server (AS)  121  and the Call Session Control Function (CSCF)  122 . CSCF  122  comprises at least a communication unit  331 , a processing unit  332  and database  333 . The communication unit  331  receives a SIP message from the HIGA  101 , the SGSN/GGSN  132  or the AS  121  and transmits the SIP message to the HIGA  101 , the SGSN/GGSN  132  or the AS  121 . A processing unit  332  controls the communication unit  331  and the database  333  and executes processing of the received SIP message according to the embodiment of the present invention. The database  333  stores information including the notification list  1000  of  FIG. 10 . 
         [0090]    The AS  121  comprises at least a communication unit  341 , a processing unit  342  and database  343 . The communication unit  341  receives SIP message from the CSCF  122  and transmits SIP message to the CSCF  122 . A processing unit  342  controls the communication unit  341  and the database  343  and executes processing of the received SIP message according to the embodiment of the present invention. The processing unit  342  also generates SIP message to be transmitted to the HIGA  101  and UE  113 . The database  343  stores information including a list  800  of  FIG. 8  and presence table  1300  of  FIG. 13 . 
         [0091]      FIG. 3A  only illustrates one example of installation of Femto-CPE  100  according to the present invention. However, the functionality of Femto-CPE  100  may be implemented differently, for example, the Femto-BS functionalities may be added to HIGA  101  using a software architectures. 
         [0092]      FIG. 4  illustrates an exemplary procedure to generate P-Access-Network-Info in the HIGA  101  according to the embodiment of the present invention. In this embodiment, the P-Access-Network-Info is utilized to associate the HIGA  101  with the UE  113 . 
         [0093]    In step S 401 , the RNC  131  configures Femto-BS  102  with cell information. The cell information may include “Mobile Country Code” (MCC), “Mobile Network code” (MNC), and “UMTS Cell Identity” (Cell-ID) and “Local Area Code” (LAC). 
         [0094]    MCC, MNC and UMTS Cell Identity are a part of RRC System Information. To be more specific, MCC and MNC belong to MIB, LAC belongs to SIB-1 and UMTS Cell Identity belongs to SIB-3. They are delivered from the RNC  131  to Femto-BS  102  using NBAP message “System Information Update”. 
         [0095]    In step S 402 , the Femto-BS  102  extracts MCC, MNC, LAC, and Cell-ID from the received NBAP message. MCC, MNC and LAC may be previously provided with Femto-BS  102  by using a SIM card to store them. Femto-BS  102  may read MCC, MNC and LAC from the SIM card and provide HIGA  101  and the UE  113 . Further, in step S 402 , the Femto-BS  102  transfers the cell information to the HIGA  101  via communication I/Fs  305  and  311 . 
         [0096]    In step S 403 , the HIGA  101  generates a P-Access-Network-Info. The P-Access-Network-Info is header information included in a SIP message. In step S 404 , when the HIGA  101  transmits IMS message, it includes the generated P-Access-Network-Info in its header.  FIG. 5  illustrates an example of P-Access-Network-Info according to the embodiment of the present invention. As is depicted in  FIG. 5 , the P-Access-Network-Info  500  is divided into two fields of access-type  501  and access-info  502 . The access-type field  501  indicates a type of radio access technology used by the apparatus to be connected to IMS network  120 . 
         [0097]    The access-type field  501  is set to any one of “3GPP-GERAN”, “3GPP-UTRAN-FDD”, “3GPP-UTRAN-TDD”, “3GPP2-1X”, “3GPP2-1X-HRPD”, “3GPP2-UMB”, “IEEE-802.11”, “IEEE-802.11a”, “IEEE-802.11b”, “IEEE-802.11g”, “ADSL”, “ADSL2”, “ADSL2+”, “RADSL”, “SDSL”, “HDSL”, “HDSL2”, “G.SHDSL”, “VDSL”, “IDSL”, or “DOCSIS” as appropriate to the access technology in use. The AS  121  may customize services according to the access-type. In this embodiment, a case in which the access-type field  501  is set to “3GPP-UTRAN-FDD” will be described as an example. 
         [0098]    In  FIG. 5 , the access-info field  502  indicates an identification of a cell. The data in the access-info  502  corresponds to the access technology in use set in the access-type field  501 . When the access-type field  501  is set to “3GPP-UTRAN-FDD”, a “utran-cell-id-3gpp” parameter is set to a concatenation of the MCC, MNC, LAC (as described in 3GPP TS 23.003) and the Cell-ID (as described in 3GPP TS 25.331). Starting with the most significant bit, MCC (3 digits), MNC (2 or 3 digits depending on MCC value), LAC (fixed length code of 16 bits using full hexadecimal representation) and UMTS Cell Identity (fixed length code of 28 bits using a full hexadecimal representation). 
         [0099]    A pair of MCC and MNC identifies a PLMN, and the Cell-ID is unique within a PLMN. Thus the combination of MCC, MNC and Cell-ID can identify a radio cell for a specific access type. 
         [0100]    When the HIGA  101  transmits a SIP message, it is routed or forked to the AS  121 . For example, the HIGA  101  can transmit REGISTER message and the AS  121  may obtain the header value by using Registration Event Package. Further details regarding Registration Event Package are described in RFC 3680 SIP Event Package for Registrations. If the HIGA  101  transmits other types of SIP messages, such as “SUBSCRIBE”, “NOTIFY”, “PUBLISH”, “MESSAGE” and “INVITE”, then their Request-URI may point to the AS  121  so that they are delivered there directly. Otherwise they are forked or routed at CSCF  122  to the AS  121  according to initial filter criteria settings of the sender, which is either the HIGA  101  or the UE  113 . 
         [0101]      FIG. 6  illustrates an exemplary procedure to generate P-Access-Network-Info in the UE  113  according to the embodiment of the present invention. 
         [0102]    In step S 601 , the Femto-BS broadcasts the cell information including MCC, MNC, LAC and the Cell-ID in BCCH logical channel. When UE enters in the Femto cell, it extracts the cell information from the BCCH logical channel in step S 602 . 
         [0103]    When the UE  113  sends an IMS message, in step S 603 , the UE  113  generates P-Access-Network-Info based on the cell information received from the Femto-BS  102 . The generated P-Access-Network-Info is the same as the P-Access-Network-Info header generated by the HIGA  101  as is illustrated in  FIG. 5 . 
         [0104]      FIG. 7  shows an example of a sequence diagram illustrating a procedure where the HIGA  101  is started (or restarted) and finds the UE  113  which newly enters the Femto Cell generated by the Femto-BS  102 . In this case, the HIGA  101  subscribes to the service provider&#39;s AS  121 . When the UE  113  also subscribes to the service provider&#39;s AS  121 , the HIGA  101  receives notification. In the situation according to  FIG. 7 , the client device is a TV connected to the HIGA. SIP URIs each assigned to the UE  113 , the HIGA  101 , the CSCF  122  and the AS  121  are as follows. 
         [0000]    UE  113 : sip:bob@operator.com
       HIGA  101 : sip:room123.Femto@operator.com   CSCF  122 : sip:cscf.operator.com
           AS  121 : sip:service@findservice.com   
               
 
         [0108]    “Bob” is a user of the UE  113  and the UE  113  is a mobile phone. “Findservice.com” is a service provider who offers the pairing service according to the present invention. Bob has signed up with them and received SIP URI sip:bob@operator.com. The HIGA has also signed up with them and received SIP URI sip:service@findservice.com. The service provider&#39;s AS  121  has subscription information including SIP URIs of the UE  113  and the HIGA  101 . 
         [0109]    In  FIG. 7 , a doted line indicates the “200 OK” response according to the SIP protocol corresponding to the SIP request immediately before it. 
         [0110]    In step S 701 , when the HIGA is started or restarted, the RNC  131  sends cell information including MCC, MNC, LAC and UMTS cell identity to the Femto-BS  102 . In step S 702 , the Femto-BS  102  provides the HIGA  101  with the received cell information and the HIGA  101  generates P-Access-Network-Info (PANI)  500 . 
         [0111]    In step S 703 , the HIGA  101  registers with the IMS network  120  by transmitting the following REGISTER message to the CSCF  122 . An example of the header portions of REGISTER message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    REGISTER sip:operator.com SIP/2.0
       To: sip:room123.femto@operator.com   Contact: 220.110.162.34       
 
         [0114]    In step S 704 , the HIGA  101  subscribes for the service provider by transmitting SUBSCRIBE message including the P-Access-Network-Info header to the AS  121  via the CSCF  122 . An example of the header portions of SUBSCRIBE message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    SUBSCRIBE sip:service@findservice.com SIP/2.0
       P-Access-Network-Info: xxx   P-Asserted-Identity:
           sip:room123.femto@operator.com (P-Asserted-Identity indicates a sender of the sip message and is attached by the CSCF  122 .)   
               
 
         [0118]    In step S 705 , the AS  121  extracts the P-Access-Network-Info  500  and the IMPU (SIP URI) of the HIGA  101  from the received SUBSCRIBE message. The AS  121  has a list of P-Access-Network-Info associated with the IMPU and updates the list by the extracted information. 
         [0119]      FIG. 8  shows the list according to the embodiment of the present invention. The list  800  includes IMPU  801  and P-Access-Network-Info 802.1MPU  801  is preliminarily provided based on the agreement between the service provider and the subscriber. In this embodiment, since the HIGA  101  has already signed up with the service provider findservice.com, the IMPU of the HIGA  101  is stored in the list  800 . In step S 705 , the AS  121  updates P-Access-Network-Info  802 , when the AS  121  receives the SUBSCRIBE message. In this embodiment, the AS  121  receives “xxx” as the P-Access-Network-Info and updates the P-Access-Network-Info  802  with the received value. 
         [0120]    When the AS  121  updates the list  800 , the AS  121  searches the list  800  for an entry having the same P-Access-Network-Info  802  as the one currently updated. In step  706 , the AS  121  transmits NOTIFY message including the found IMPU. The found IMPU can be set to the SIP header or in the message body. Even if there is no entry having the same P-Access-Network-Info in the list  800 , the AS  121  transmits the NOTIFY message without the IMPU. An example of the header portions of NOTIFY message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment.
       NOTIFY sip:room123.femto@operator.com       
 
         [0122]    When the UE  113  enters the Femto-Cell generated by the Femto-BS in Femto-CPE  100 , the UE  113  in step S 707  receives the cell information broadcasted from the Femto-BS  102 . In step S 708 , PDP Context is activated in order to access the IMS network  120  between the UE  113  and the SGSN/GGSN  132 . 
         [0123]    In step S 709 , the UE  113  registers with the IMS network  120  by transmitting the following REGISTER message to the CSCF  122 . An example of the header portions of REGISTER message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    REGISTER sip:operator.com SIP/2.0
       To: sip:bob@operator.com   Contact: 61.196.102.213       
 
         [0126]    In step S 710 , the UE  113  subscribes for the service provider by transmitting a SUBSCRIBE message including the P-Access-Network-Info header to the AS  121  via the CSCF  122 . An example of the header portions of SUBSCRIBE message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    SUBSCRIBE sip:service@findservice.com SIP/2.0
       P-Access-Network-Info: xxx   P-Asserted-Identity: sip:bob@operator.com (P-Asserted-Identity indicates a sender of the sip message and is attached by the CSCF  122 .)       
 
         [0129]    In the embodiment of the present invention, if the UE  113  is located in the Femto Cell generated by the Femto-BS  102 , P-Access-Network-Info included in the SUBSCRIBE messages respectively received from the HIGA in step S 704  and the UE  113  in step S 710  are the same. In step S 711 , the AS  121  extracts the P-Access-Network-Info  500  and the IMPU (SIP URI) of the UE  113  from the received SUBSCRIBE message. The AS  121  updates the list  800  in  FIG. 8 , by the extracted value from the SUBSCRIBE message. 
         [0130]    When the AS  121  updates the list  800 , the AS  121  searches the list  800  for such an entry having the same P-Access-Network-Info  802  as the one currently updated. At this time, the AS  121  finds a pair of entries each having the same P-Access-Network-Info. The AS  121  transmits NOTIFY messages to each entry of the found pair including others&#39; IMPUs in the following steps. 
         [0131]    In step S 712 , the AS  121  transmits NOTIFY message including the IMPU of the UE  113  to the HIGA  101 . The IMPU (sip:bob@operator.com) to be informed to the HIGA  101  may be attached to the header of the message or to a message body. In step S 713 , the AS  121  transmits NOTIFY message including the IMPU of the HIGA  101  to the UE  113 . The IMPU (sip:room123.femto@operator.com) to be informed to the UE  113  may be attached to the header of the message or to a message body. An example of the header portions of NOTIFY message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0132]    (For S 712 )
       NOTIFY sip:room123.femto@operator.com SIP/2.0   Same-PANI-IMPU: bob@operator.com       
 
         [0135]    (For S 713 )
       NOTIFY sip:bob@operator.com SIP/2.0   Same-PANI-IMPU: room123.femto@operator.com       
 
         [0138]    According to this embodiment, the HIGA  101  and the UE can obtain a SIP URI from the received NOTIFY messages in order to communicate with each other. 
         [0139]    In step S 714 , the UE  113  transmits PUBLISH SIP message including P-Access-Network-Info to the service provider&#39;s AS  121  via CSCF  122 . The PUBLISH message also includes presence information of the UE  113  (Presence document # 1 ). An example of the header portions of PUBLISH message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    PUBLISH sip:service@findservice.com SIP/2.0
       P-Access-Network-Info: xxx   P-Asserted-Identity: sip:bob@operator.com       
 
         [0142]    When the AS  121  receives the presence information, the AS  121  in step S 715  searches the list  800  for the same value as the P-Access-Network-Info included in the received PUBLISH message. In this embodiment, P-Access-Network-Info of the HIGA  101  is the same as the one of the UE  113 . 
         [0143]    In step S 716 , the AS  121  transmits NOTIFY message including the presence information (Presence document # 1 ) of the UE  113  with the IMPU. The IMPU (sip:bob@operator.com) to be informed to the HIGA  101  may be attached to the header of the message or to a message body. An example of the header portions of NOTIFY message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    NOTIFY sip:room123.femto@operator.com SIP/2.0
       Same-PANI-IMPU: sip:bob@operator.com       
 
         [0145]    When the HIGA  101  receive the NOTIFY message, it may trigger some action on the connected client devices, such as turning on a room light. 
         [0146]    The HIGA  101  is monitoring any of client devices connected to it is turns on based on, for example, UPnP discovery procedure. If the user turns on the TV  111  in the room, in step S 717 , it triggers UPnP discovery procedure and the HIGA  101  finds the TV  111 . 
         [0147]    If the device is discovered, in step S 718 , the HIGA  101  transmits PUBLISH message to the service provider&#39;s AS  121  via CSCF  122  with P-Access-Network-Info. The PUBLISH message also includes presence information regarding available client devices for the UE  113  including TV  111  (Presence document # 2 ). In this embodiment, the presence information includes a control URI of the corresponding client device stored in the Device DB  302 . An example of the header portions of PUBLISH message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    PUBLISH sip:service@findservice.com SIP/2.0
       P-Access-Network-Info: xxx   P-Asserted-Identity:
           sip:room123.femto@operator.com   
               
 
         [0151]    When the AS  121  receives the presence information, in step S 719 , the AS  121  searches the list  800  for the same value as the P-Access-Network-Info included in the received PUBLISH message. In this embodiment, P-Access-Network-Info of the UE  113  is the same as the one of the HIGA  101 . 
         [0152]    In step S 720 , the AS  121  transmits NOTIFY message including the presence information (Presence document # 2 ) received from the HIGA  101  with the IMPU. The IMPU (sip:room123.femto@operator.com) to be informed to the UE  113  may be attached to the header of the message or to a message body. An example of the header portions of NOTIFY message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    NOTIFY sip:bob@operator.com SIP/2.0
       Same-PANI-IMPU: sip:room123.femto@operator.com       
 
         [0154]    When the UE  113  receive this NOTIFY message, it can control TV  111  using the control URI included in the received SIP message. 
         [0155]    In the above described embodiment, although the UE  113  is notified of the HIGA  101 &#39;s public identity (sip:room123.femto@operator.com) and the HIGA  101  is notified of the UE  113 &#39;s public identity (sip:bob@operator.com), one way notification may be sufficient. How to provide information to each other depends on which of HIGA  101  and the UE initiates the session setup. 
         [0156]    According to the procedure of  FIG. 7 , when the mobile user Bob who has the UE  113  stays at a room  123  in a certain hotel where the Femto-CPE locates, he can get a video clip stored in his home server connected through the IMS network  120  by accessing from his UE  113 , and watch it on the large TV  111  using the received control URI in step S 720 . 
         [0157]      FIG. 9  shows another example of a sequence diagram illustrating a procedure where the HIGA  101  finds the UE  113  which newly enters the Femto Cell generated by the Femto-BS  102 . In this case, the service provider&#39; AS  121  subscribes to the CSCF  122  so that it can receive a notification upon a change in a registration status of the HIGA  101  or the UE  113 . 
         [0158]    In the situation according to  FIG. 9 , SIP URIs each assigned to the UE  113 , the HIGA  101 , the CSCF  122  and the AS  121  are the same as the situation according to  FIG. 7 . 
         [0159]    In  FIG. 9 , a dotted line also indicates the “200 OK” response according to the SIP protocol corresponding to the SIP request immediately before it. 
         [0160]    In step S 901 , the service provider&#39;s AS  121  subscribes to the CSCF  122  to receive a notification regarding a change in registration status of their contracted customers. The AS  121  has a list of the contracted customers including SIP URI assigned to at least the HIGA  101  and the UE  113 . The AS  121  transmits SUBSCRIBE message for each of SIP URIs to the CSCF  122 . 
         [0161]    An example of the header portions of SUBSCRIBE message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    SUBSCRIBE sip:room123.femto@operator.com SIP/2.0
       Event: reg   Contact: sip:service@findservice.com
 
SUBSCRIBE sip:bob@operator.com SIP/2.0
   Event: reg   Contact: sip:service@findservice.com       
 
         [0166]    In the above, “Event: reg” indicates that this 
         [0167]    SUBSCRIBE message relates to a request the CSCF to notify to the AS  121  if a register event from the specified SIP URI (sip:room123.femto@operator.com or sip:bob@operator.com) occurs according to the standards of the corresponding RFC 3680. “Contact” header is set to the destination address of NOTIFY message, i.e. the AS  121  (sip:service@findservice.com). When the AS  121  transmits the SUBSCRIBE message, it does not have to involve the P-Asserted-Identity in the message. 
         [0168]    In step S 902 , the CSCF creates a notification list based on the received SUBSCRIBE messages from the AS  121 . 
         [0169]      FIG. 10  shows the notification list according to the embodiment of the present invention. The list  1000  includes IMPU  1001  and destination address  1002 . The specified SIP URI in SUBSCRIBE message is stored in IMPU  1001 . SIP URI set in “Contact” field in SUBSCRIBE message is stored destination address  1002  associated with the corresponding specified address. 
         [0170]    Since procedures in step S 903  and  5904  correspond to procedures in step S 701  and  5702  in  FIG. 7  and the detail descriptions are omitted. 
         [0171]    In step S 905 , the HIGA  101  registers with the IMS network  120  by transmitting the following REGISTER message to the CSCF  122 . An example of the header portions of REGISTER message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    REGISTER sip:operator.com SIP/2.0
       To: sip:room123.femto@operator.com   Contact: 220.110.162.34   P-Access-Network-Info: xxx       
 
         [0175]    In this embodiment according to  FIG. 9 , REGISTER message should include P-Access-Network-Info generated based on the received cell information. 
         [0176]    In step S 906 , the CSCF  122  determines whether or not the registration event should notify the AS  121  by searching the SIP URI included in the REGISTER message (i.e. sip:room123.femto@operator.com) for the notification list  1000 . If the CSCF  122  finds the corresponding SIP URI in the notification list, the CSCF  122  transmits NOTIFY message to the AS  121  in step S 907 . The NOTIFY message contains the registration information document # 1  in the message body. An example of the header portions of NOTIFY message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    NOTIFY sip:service@findservice.com SIP/2.0
       Event: reg       
 
         [0178]    In this embodiment, registered SIP URI to the CSCF  122  is attached to the message body as “Registration information document # 1 ” in XML format according to RFC3680 standard. The CSCF also involve P-Access-Network-Info extracted from the received REGISTER message in step S 905  into the “Registration information document # 1 ”. 
         [0179]      FIG. 11  shows an example of “Registration information document # 1 ” according to the present embodiment. In  FIG. 11 , the underlined portion  1101  shows the registered SIP URI to the CSCF  122  and the underlined portion  1102  shows P-Access-Network-Info from the registered device. 
         [0180]    In step S 908 , the AS  121  extracts the P-Access-Network-Info  500  and the IMPU (SIP URI) of the HIGA  101  from the attached document to the NOTIFY message. The AS  121  has the list  800  as is depicted in  FIG. 8  and updates the list  800  by the received information. 
         [0181]    Since procedures in step S 909  and  5910  correspond to procedures in step S 706  and  5707  in  FIG. 7  and the detail descriptions are omitted. 
         [0182]    In step S 911 , the UE  113  registers with the IMS network  120  by transmitting the following REGISTER message to the CSCF  122 . An example of the header portions of REGISTER message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    REGISTER sip:operator.com SIP/2.0
       To: sip:bob@operator.com   Contact: 61.196.102.213   P-Access-Network-Info: xxx       
 
         [0186]    In this embodiment according to  FIG. 9 , REGISTER message should include P-Access-Network-Info generated based on the received cell information. 
         [0187]    In step S 912 , the CSCF  122  determines whether or not the registration event should notify the AS  121  by searching the SIP URI included in the REGISTER message (i.e. sip:bob@operator.com) for the notification list  1000 . If the CSCF  122  finds the corresponding SIP URI in the notification list, the CSCF  122  transmits NOTIFY message to the AS  121  in step S 913 . The NOTIFY message contains the registration information document # 2  in the message body. 
         [0188]    An example of the header portions of NOTIFY message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    NOTIFY sip:service@findservice.com SIP/2.0
       Event: reg       
 
         [0190]    In this embodiment, registered SIP URI (i.e. sip:bob@operator.com) is attached to the message body as “Registration information document # 2 ” in XML format according to RFC3680 standard. The CSCF also involves P-Access-Network-Info extracted from the received REGISTER message in step S 912  into the “Registration information document # 2 ”. 
         [0191]    In step S 914 , the AS  121  extracts the P-Access-Network-Info  500  and the IMPU (SIP URI) of the HIGA  101  from the attached document to the NOTIFY message. The AS  121  has the list  800  as is depicted in  FIG. 8  and updates the list  800  by the received information. 
         [0192]    When the list  800  is updated, in step S 915 , the AS  121  searches the list  800  for the same value as the updated P-Access-Network-Info. In this embodiment, P-Access-Network-Info of the HIGA  101  is the same as the one of the UE  113 . If the AS  121  finds a set of P-Access-Network-Info  800  respectively associated with the different IMPU  801 , the AS  121  transmits SIP message to a respective destination as follows. 
         [0193]    In step S 916 , the AS  121  transmits MESSAGE message to HIGA  101  with IMPU of the UE  113  as a public identity. An example of the header portions of MESSAGE message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    MESSAGE sip:room123.femto@operator.com SIP/2.0
       Same-PANI-IMPU: sip:bob@operator.com       
 
         [0195]    The IMPU (sip:bob@operator.com) to be informed to the HIGA  101  may be attached to the header of the message or to a message body. 
         [0196]    In step S 917 , the AS  121  transmits MESSAGE to UE  113  with IMPU of the HIGA  101  as a public identity. An example of the header portions of MESSAGE message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0000]    MESSAGE sip:bob@operator.com SIP/2.0
       Same-PANI-IMPU: sip:room123.femto@operator.com       
 
         [0198]    The IMPU (sip:room123.femto@operator.com) to be informed to the UE  113  may be attached to the header of the message or to a message body. 
         [0199]    HIGA  101  knows that now the UE exists in the room and offers some services, such as list of TV-programs that a user of the UE can selects using his/her UE. 
         [0200]      FIG. 12  shows further example of a sequence diagram illustrating a procedure where the HIGA  101  finds the UE  113  which newly enters the Femto Cell generated by the Femto-BS  102 . In this case, the AS  121  behaves as a IMS operator&#39;s presence server which provides presence information to the HIGA  101  and UE  113 . 
         [0201]    In the situation according to  FIG. 12 , SIP URIs each assigned to the UE  113 , the HIGA  101  and the CSCF  122  are the same as the situation according to  FIG. 7 . SIP URI assigned to the AS is as follows.
       AS  121 : sip:ps.operator.com       
 
         [0203]    In  FIG. 12 , a doted line also indicates the “200 OK” response according to the SIP protocol corresponding to the SIP request immediately before it. 
         [0204]    In  FIG. 12 , since the processing according to steps S 1201  through steps  51203  are similar to the processing according to steps  5701  through s 703  of  FIG. 7 , the corresponding descriptions are omitted. 
         [0205]    In step S 1204 , the HIGA  101  subscribes for its presence by transmitting SUBSCRIBE message including the P-Access-Network-Info header to the AS  121  via the CSCF  122 . Routing at the CSCF  122  to the AS  121  is done based on the HIGA  101 &#39;s Initial Filter Criteria (IFC). An example of the header portions of SUBSCRIBE message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standard of RFC and 3GPP and their explanation will be omitted in this embodiment.
       SUBSCRIBE sip:room123.femto@operator.com SIP/2.0   Event: presence   P-Access-Network-Info: xxx       
 
         [0209]    In step S 1205 , the AS  121  extracts the P-Access-Network-Info  500  and the IMPU (SIP URI) of the HIGA  101  from the received SUBSCRIBE message. The AS  121  has a presence table including presence information associated with PANI and the IMPU, and updates the presence table by the extracted information. 
         [0210]      FIG. 13  shows the presence table  1300  according to the embodiment of the present invention. The presence table  1300  includes IMPU  1301 , P-Access-Network-Info (PANI)  1302  and presence document  1303 . IMPU  1301  and PANI  1302  are the same as those have already been described above. In presence information  1303 , presence documents are stored associated with the IMPU  1301  and PANI  1302 , respectively. Each of the presence documents includes a status of the corresponding apparatus. 
         [0211]    When the AS  121  updates the presence table  1300 , the AS  121  searches the table for such an entry having the same PANI  1302  as the one currently updated. In step  1206 , the AS  121  transmits NOTIFY message with the presence information of the HIGA  101 . If the AS  121  found the entry having the same PANI as the one of the HIGA  101 , the attached presence information includes the corresponding IMPU  1301  of the found entry. Even if there is no entry having the same PANI in the presence table  1300 , the AS  121  transmits the NOTIFY message with the presence information not including IMPU  1301 . An example of the header portions of NOTIFY message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment.
       NOTIFY sip:room123.femto@operator.com       
 
         [0213]    In  FIG. 12 , since the processing according to steps S 1207  through steps  51209  are similar to the processing according to steps  5707  through s 709  of  FIG. 7 , the corresponding descriptions are omitted. 
         [0214]    In step S 1210 , the UE  113  subscribes for its presence by transmitting SUBSCRIBE message including the P-Access-Network-Info header to the AS  121  via the CSCF  122 . Routing at the CSCF  122  to the AS  121  is done based on the&#39;s Initial Filter Criteria (IFC). An example of the header portions of SUBSCRIBE message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standard of RFC and 3GPP and their explanation will be omitted in this embodiment.
       SUBSCRIBE sip:bob@operator.com SIP/2.0   Event: presence   P-Access-Network-Info: xxx       
 
         [0218]    In step S 1211 , the AS  121  extracts the P-ANI  500  and the IMPU (SIP URI) of the UE  113  from the received SUBSCRIBE message. The AS  121  updates presence table  1300  by the extracted values from the SUBSCRIBE message. 
         [0219]    When the AS  121  updates the presence table  1300 , the AS  121  searches the table  1300  for such an entry having the same PANI  1302  as the one currently updated. At this time, the AS  121  finds a pair of entries each having the same PANI. The AS  121  transmits NOTIFY messages to each entry of the found pair with the updated presence information in the following steps. 
         [0220]    In step S 1212 , the AS  121  transmits NOTIFY message with the presence information of the HIGA  101 , the presence information includes the IMPU of the UE  113  as is depicted at an underline portion  1401  in FIG.  14 . In step S 1213 , the AS  121  transmits NOTIFY message with the presence information of the UE  113 , the presence information includes the IMPU of the HIGA  101  as is depicted at an underline portion  1501  in  FIG. 15 . 
         [0221]    An example of the header portions of NOTIFY message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0222]    (For the HIGA)
       NOTIFY sip:room123.femto@operator.com SIP/2.0   Event: presence       
 
         [0225]    (For the UE)
       NOTIFY sip:bob@operator.com SIP/2.0   Event: presence       
 
         [0228]    According to this embodiment, the HIGA  101  and the UE can obtain SIP URI from the received presence information to communicate with each other. 
         [0229]    In the above embodiments, the HIGA  101  and the Femto-BS  102  are integrated into a single device. However, the implementation according to the embodiment of the present invention is not limited to this. For example, the HIGA  101  and the Femto-BS  102  may be separately located and connected over local area network (LAN) using a wired or wireless connection. Note that although IP level connectivity is assumed between the HIGA  101  and the Femto-BS  102 , the connection is not used to transmit user data from the UE  113 . UPnP or SIP protocol is well suited as a protocol between the HIGA  101  and the Femto-BS  102  because the HIGA  101  has UPnP Control Point and SIP B2BUA functionalities. The Femto-BS  102  may generate P-Access-Network-Info and give it to HIGA  101  over the LAN, or Femto-BS  102  may give information necessary for generating P-Access-Network-Info to the HIGA  101 . 
         [0230]    Femto-BS  102  may generate more than one Femto-cell, which means Femto-BS  102  has more than one sector. One scenario may be to allocate a first sector (sector  1 ) to one room (room  1 ) and a second sector (sector  2 ) to another room (room  2 ) next to the room  1 . In this situation, P-Access-Network-Info takes different values between sector  1  and sector  2 . One way to avoid mixing up these two rooms is to allocate different IMPU to each sector and expose them to the AS  121 . One to one mapping between P-Access-Network-Info and IMPU makes it possible for the AS  121  to deliver IMS message to the correct room. 
         [0231]    This invention offers mobile phone users an easy way to discover the HIGA  101  and services offered by it, when the HIGA  101  is collocated with Femto-BS  102 , even if the user&#39;s mobile phone doesn&#39;t have local connectivity to HIGA  101  using wireless LAN. 
         [0232]    This invention does not require implementing RNC, GGSN and SGSN functionalities in the Femto CPE and thus it does not increase complexity and cost. 
         [0233]    In the followings, further embodiments according to installation of HIGA  101  and WLAN-AP  103  in an indoor situation as is depicted in  FIG. 2  are described. 
         [0234]      FIG. 3D  illustrates an exemplary HIGA  101  and WLAN-AP  103  according to the embodiment of the present invention. 
         [0235]    The hardware configuration of the HIGA  101  according to the present invention is similar to the one depicted in  FIG. 3A . The HIGA  101  includes at least ISIM  301 , Device DB  302 , SIP UA/UA Proxy Unit  303 , B2BUA  304 , wireless communication I/F  307 , and a control and processing unit  306 . 
         [0236]    The communication between the HIGA  101  and the client device  111  or  112  are established via the WLAN  1  generated by the WLAN-AP  103 . The communication I/F  307  is an interface for wireless communication between the HIGA  101  and the client device. 
         [0237]    The WLAN-AP  103  includes at least a transceiver  351  a control and processing unit  352 . The transceiver  351  generates the WLAN  1  ( 104 ) to provide communication between the HIGA  101  and the client devices. The transceiver  351  also generates WLAN  2  ( 105 ) for the UE  113  to communicate with the PDG  134  via broadband access network  140  and WAG  133 . 
         [0238]    The control and processing unit  352  which controls the overall processing in the WLAN-AP  103  including SIP message generation and UPnP device discovery function. The control and processing unit  352  is connected to Broadband Access Network  140  which in turn is connected to WAG  133  to transmit and receive information including SIP message. 
         [0239]      FIG. 16  shows an example of a sequence diagram illustrating a procedure where the HIGA  101  is started (or restarted) and finds the UE  113  which newly connects to the WLAN  2  generated by the WLAN-AP  103 . In this case, the HIGA  101  subscribes to the service provider&#39;s AS  121 . When the UE  113  also subscribes to the service provider&#39;s AS  121 , the HIGA  101  receives notification. 
         [0240]    In the situation according to  FIG. 16 , the client device is a TV connected to the HIGA. SIP URIs each assigned to the UE  113 , the HIGA  101 , the CSCF  122  and the AS  121  are the same in the situation according to  FIG. 7 . 
         [0241]    In  FIG. 16 , a doted line indicates the “200 OK” response according to the SIP protocol corresponding to the SIP request immediately before it. 
         [0242]    In step S 1601 , when the HIGA is started or restarted, the HIGA sets up a wireless connection between the WLAN-AP  103  via WLAN  1  and obtains MAC address of the WLAN-AP  103 . In step S 1602 , the HIGA  101  generates P-Access-Network-Info (PANI)  500  using the obtained MAC address of the WLAN-AP according to 3GPP TS 24.229 (V7.11.0), 7.2A.4. Thus, in this embodiment, the access-type field  501  is, for example, set to “IEEE-802.11g” and the access-info field  502  indicates the MAC address. 
         [0243]    In step S 1603 , the HIGA  101  transmits SIP message including the generated PANI  500  to the AS  121 . An example of the header portions of SIP message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment.
       SUBSCRIBE sip:service@findservice.com SIP/2.0   P-Access-Network-Info: xxx   P-Asserted-Identity:
           sip:room123.femto@operator.com (P-Asserted-Identity indicates a sender of the sip message and is attached by the CSCF  122 .)   
               
 
         [0248]    In step S 1604 , the AS  121  extracts the P-Access-Network-Info  500  and the IMPU (SIP URI) of the HIGA  101  from the received SIP message. The AS  121  has a list of P-Access-Network-Info associated with the IMPU and updates the list by the extracted information. The list is similar to the list  800  of  FIG. 8 . In this embodiment, the AS  121  receives “xxx” as the P-Access-Network-Info and updates the P-Access-Network-Info  802  with the received value. 
         [0249]    When the AS  121  updates the list  800 , the AS  121  searches the list  800  for such an entry having the same P-Access-Network-Info  802  as the one currently updated. In step  1605 , the AS  121  transmits NOTIFY message including the found IMPU. Even if there is no entry having the same P-Access-Network-Info in the list  800 , the AS  121  transmits the NOTIFY message without the IMPU. An example of the header portions of NOTIFY message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment.
       NOTIFY sip:room123.femto@operator.com SIP/2.0       
 
         [0251]    In step S 1606 , the UE  113  set up wireless connection between the WLAN-AP  103  via WLAN  2  and obtains the MAC address of WLAN-AP  103  using ARP for example. In step S 1607 , the UE  113  generates P-Access-Network-Info  500  using the obtained PANI  500 . The generated PANI by the UE  113  is the same as the one generated by the HIGA in step S 1602 . 
         [0252]    In step S 1608 , the UE  113  and 3GPP AAA/HSS  135  performs mutual authentication according to 3GPP TS 33.234 and TS 23.234. In step S 1609 , the UE  113  and the PDG  134  setups the secure IP tunnel  141  according to TS 33.234 and TS 23.234. 
         [0253]    In step S 1610 , the UE  113  transmits SIP message including the generated PANI  500  to the AS  121 . An example of the header portions of SIP message necessary for explanation of this embodiment is shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment.
       SUBSCRIBE sip:service@findservice.com SIP/2.0   P-Access-Network-Info: xxx   P-Asserted-Identity: sip:bob@operator.com (P-Asserted-Identity indicates a sender of the sip message and is attached by the CSCF  122 .)       
 
         [0257]    In step S 1611 , the AS  121  extracts the P-Access-Network-Info  500  and the IMPU (SIP URI) of the UE  113  from the received SIP message. The AS  121  updates the list  800  by the extracted value from the SIP message. 
         [0258]    When the AS  121  updates the list  800 , the AS  121  searches the list  800  for such an entry having the same P-Access-Network-Info  802  as the one currently updated. At this time, the AS  121  finds a pair of entries each having the same P-Access-Network-Info. The AS  121  transmits NOTIFY messages to each entry of the found pair including other&#39;s IMPU in the following steps. 
         [0259]    In step S 1612 , the AS  121  transmits NOTIFY message including the IMPU of the UE  113  to the HIGA  101 . The IMPU (sip:bob@operator.com) to be informed to the HIGA  101  may be attached to the header of the message or to a message body. In step S 1613 , the AS  121  transmits NOTIFY message including the IMPU of the HIGA  101  to the UE  113 . The IMPU (sip:room123.femto@operator.com) to be informed to the UE  113  may be attached to the header of the message or to a message body. An example of the header portions of NOTIFY message necessary for explanation of this embodiment are shown as follows. Other portions which should be included in the header correspond to the standards of the corresponding RFC and 3GPP and their explanation will be omitted in this embodiment. 
         [0260]    (For the HIGA  101 )
       NOTIFY sip:room123.femto@operator.com SIP/2.0   Same-PANI-IMPU: sip:bob@operator.com       
 
         [0263]    (For the UE  113 )
       NOTIFY sip:bob@operator.com SIP/2.0   Same-PANI-IMPU: sip:room123.femto@operator.com       
 
         [0266]    According to this embodiment, the HIGA  101  and the UE can obtain SIP URI from the received NOTIFY messages to communicate with each other. The UE  113  may access to the TV  111  through the IMS network  120  using the secure IP tunnel  141 . 1   
         [0267]    In the situation according to  FIG. 2 , it is also possible to transmit PUBLISH message to the AS  121  from HIGA  101  or UE  113  as is depicted in step S 714  and  5718  of  FIG. 7  and to receive NOTIFY message from AS  121  at HIGA  101  or UE  113  as is depicted in step S 716  and  5720  of  FIG. 7 . 
         [0268]    Further, the sequence diagram illustrated in  FIG. 16  can be modified according to  FIG. 9  or  12  without changing the P-Access-Network-Info generation process in step S 1601 , S 1602  S 1606 , and S 1607 , the authentication process in step S 1608  and the secure IP tunnel establishing process in step S 1609 . 
         [0269]    Thus, it is possible for an operator of the WLAN-AP  103  such as the hotel staff, to delegate authentication of the UE  113  to the IMS operator which owns the IMS network  120 . When UE  113  requests remote access to the HIGA  101  in the room  123  by using IMS messages, the CSCF  121  attaches the UE&#39;s public user identity (IMPU) as P-Asserted-Identity header which has already been authenticated in the IMS network  120 . 
         [0270]    It is also possible for the room owner such as the hotel to delegate charging of service usage to the IMS operator which owns the IMS network  120 . The IMS network  120  can monitor any control and data flow between the UE  113  and the HIGA  101  in case of remote access and thus can charge the TV service to her telephone bill. 
         [0271]    Furthermore, it is possible to distinguish the internet access made by the UE  113  from the access made by other users on WLAN 1  or WLAN 2 , because PDG  134  assigns a public IP address different from the one used by WLAN-AP  103 . In case the UE  113  uses the same public IP address as the users of WLAN 1  ( 104 ), if the user has committed a crime such as posting an illegal picture on a web site, it is impossible to detect it in the access log if the user did it or someone using the WLAN 1  did it. 
         [0272]    An issue with this deployment is that the UE  113  cannot find HIGA  101  and TV  111  belonging to WLAN 1  ( 104 ) directly. The present invention according to the embodiment solves the issue by applying the same usage of P-Access-Network-Info as Femto-BS  102  situation.