Abstract:
A method and apparatus for configuring Femto Devices in an Ultra Mobile Broadband network system. A Femto Device transmits a Femto pilot signal to an Access Terminal, which is served by a plurality of base stations in the Ultra Mobile Broadband network system. The Access Terminal then transmits to the Femto Device an identifier of a base station that controls a macrocell where the Femto Device is located. Next, a Neighbor Discovery Request message is transmitted from the Femto Device to the base station in dependence upon the received identifier of the base station. In response to the Neighbor Discovery Request message received, a Neighbor Discovery Report message is transmitted from the base station to the Femto device. The Neighbor Discovery Report message includes a field indicating network addresses of a Session Reference Network Controller and an Access Gateway that connect to the base station. Finally, the Femto Device connects to the Session Reference Network Controller and the Access Gateway via the Femto device in dependence upon the network addresses of the Session Reference Network Controller and the Access Gateway.

Description:
CLAIM OF PRIORITY 
       [0001]    This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from a provisional application earlier filed in the U.S. Patent &amp; Trademark Office on 24 Aug. 2007 and there duly assigned Ser. No. 60/935,679. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a method and apparatus for configuring Ultra Mobile Broadband Femto Devices. 
         [0004]    2. Description of the Related Art 
         [0005]    Femto Devices are base stations that support a very small cell radius. Typically, the Femto Device will be deployed in a home environment which has poor coverage from the larger maro cell where the Femto Device resides. Femto Devices are expected to be widely deployed in the coming year. 
         [0006]    In the third Generation Partnership Project 2 (3GPP2) Interoperability Specification (A.S0020), an Inter-Access Network Signaling (IAS) protocol is defined for networks that support Ultra Mobile Broadband technology (UMB). UMB requires all base stations (BSs) serving a particular Access Terminal (AT) to be interconnected via an IP network, because packets destined to or arriving from the AT may be sent from or received on any BS that the AT is connected to. One method by which BSs can discover their neighbor base stations is through the use of IAS-Neighbor Discovery Report messages, which the BSs send to each other to report Access Network IDs (ANIDs—essentially IP addresses) of neighboring BSs as well as other UMB-related information about neighboring cells. The IAS-Neighbor Discovery Report message as defined in A.S0020 includes only information about immediate neighbors of the BS that transmits the IAS-Neighbor Discovery Report message. 
         [0007]    In UMB networks, serving BSs must also connect to a Session Reference Network Controller (SRNC) which hosts an Anchor Route for the UMB session. All BSs serving the AT must use the same SRNC. In addition, it is desirable that all BSs serving the AT be connected to the same Access Gateway (AGW). 
         [0008]    In a typical UMB Femto Device deployment, the Femto Device and the BS that controls the macrocell that the Femto Device resides in will need to be able to communicate via the UMB network protocols. In addition, in order for the UMB air interface to work properly (e.g. allow for smooth handoffs between the Femto Device and the macrocell), the Femto Device should connect to the same SRNC and AGW that the macrocell BS is connected to. 
         [0009]    Contemporarily, the IAS-Neighbor Discovery Report message only contain ANIDS and sector information of the immediate neighbors of the BS that transmits the IAS-Neighbor Discovery Report message. For a deployment of many Femto Devices over a large area (possibly serviced by many macro BSs), each Femto Device would need to be individually provisioned with the IP addresses of the SRNC and AGW used by the macrocell BS where the Femto Device resides. This makes for a very cumbersome Operations, Administration, and Maintenance (OA&amp;M) process, whereby a central management system must first geographically locate the Femto Device when the Femto device is initialized, identify the most likely macrocell that the Femto Device resides in, identify the BS that controls that macrocell, and then identify the SRNC and AGW that host that BS. There exists a need in the art for a more dynamic signaling method by which the Femto Device can attain the SRNC and AGW connection information directly from the BS that is controlling the macrocell that the Femto Device is residing in. 
       SUMMARY OF THE INVENTION 
       [0010]    It is therefore an object of the present invention to provide an improved method and apparatus for configuring UMB Femto Devices. 
         [0011]    It is another object of the present invention to provide an improved method for UMB Femto Devices to obtain information of the Session Reference Network Controller (SRNC) and the Access Gateway. 
         [0012]    According to one aspect of the present invention, a method for communication is provided. In this method, a Neighbor Discovery Report message is transmitted from a first base station to a second base station in an Ultra Mobile Broadband network system. The Neighbor Discovery Report message includes network addresses of an Access Gateway and a Session Reference Network Controller that connect to the first base station. 
         [0013]    The second base station may be a Femto Device which controls a Femto Cell, and which is located in a macro cell controlled by the first base station. 
         [0014]    The first base station and the Femto Device may communicate with each other via an Ultra Mobile Broadband network protocol. 
         [0015]    In response to the Neighbor Discovery Report message received from the first base station, the second base station may connect to the Access Gateway and the Session Reference Network Controller in dependence upon the network addresses of the Access Gateway and the Session Reference Network Controller. 
         [0016]    The step of transmitting the Neighbor Discovery Report message may be performed in response to a Neighbor Discovery Request message received from the second base station. 
         [0017]    The Neighbor Discovery Report message may include information regarding neighboring base stations of the first base station. 
         [0018]    The Neighbor Discovery Report message may include an Ultra Mobile Broadband Connection Information element carrying the network addresses of the Access Gateway and the Session Reference Network Controller that the first base station is connected to. The Ultra Mobile Broadband Connection Information element may include an Information Element Identity field, a Length field, an Access Gateway Address Type field, an Access Gateway Address field, a Session Reference Network Controller Address Type field, and a Session Reference Network Controller Address field. The Information Element may contain multiple instances of this information. 
         [0019]    According to another aspect of the present invention, a method for configuring Femto Devices is provided. In this method, a Femto pilot signal is transmitted from a Femto device to an Access Terminal, which is served by a plurality of base stations in the Ultra Mobile Broadband network system. The plurality of base stations connect to a Session Reference Network Controller and an Access Gateway, and each base station covers and controls a macrocell where a plurality of Femto devices are located. Then, an identifier of a base station that controls a macrocell where the Femto Device is located is transmitted from the Access Terminal to the Femto Device. Next, a Neighbor Discovery Request message is transmitted from the Femto Device to the base station in dependence upon the received identifier of the base station. In response to the Neighbor Discovery Request message received, a Neighbor Discovery Report message is transmitted from the base station to the Femto device. The Neighbor Discovery Report message includes a field indicating network addresses of the Session Reference Network Controller and the Access Gateway that connect to the base station. Finally, the Femto Device connects to the Session Reference Network Controller and the Access Gateway via the Femto device in dependence upon the network addresses of the Session Reference Network Controller and the Access Gateway. 
         [0020]    According to still another aspect of the present invention, a base station in an Ultra Mobile Broadband network system is provided. The base station transmits a Neighbor Discovery Report message. The Neighbor Discovery Report message includes network addresses of an Access Gateway(s) and a Session Reference Network Controller(s) that connect to the base station. 
         [0021]    According to a further aspect of the present invention, a Femto Device in an Ultra Mobile Broadband network system is provided. The Femto Device transmits a Neighbor Discovery Request message to a base station which controls a macro cell where the Femto Device is located. The Femto Device then receives a Neighbor Discovery Report message from the base station. The Neighbor Discovery Report message includes a field indicating network addresses of a Session Reference Network Controller and an Access Gateway that connect to the base station. Subsequently, the Femto Device to the Session Reference Network Controller and the Access Gateway in dependence upon the network addresses of the Session Reference Network Controller and the Access Gateway. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
           [0023]      FIG. 1  schematically illustrates an Ultra Mobile Broadband (UMB) Radio Access Network (RAN) deploying a Femto device according to one embodiment of the principles of the present invention; 
           [0024]      FIG. 2  schematically illustrates a configuration process for a Femto device as one embodiment according to the principles of the present invention; 
           [0025]      FIGS. 3A and 3B  schematically illustrate the format of the enhanced Inter-Access Network Signaling Neighbor Discovery Report message as an embodiment according to the principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Aspects, features, and advantages of the invention are readily apparent from the following detailed description, simply by illustrating a number of particular embodiments and implementations, including the best mode contemplated for carrying out the invention. The invention is also capable of other and different embodiments, and its several details can be modified in various obvious respects, all without departing from the spirit and scope of the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. The invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. 
         [0027]    This application incorporates by reference the third Generation Partnership Project 2 (3GPP2) Interoperability Specification (A.S0020). 
         [0028]      FIG. 1  schematically illustrates an Ultra Mobile Broadband (UMB) Radio Access Network (RAN) deploying a Femto device. UMB network  100  includes an access terminals (AT)  120  which originates a UMB session. AT  120  is served by a plurality of base stations (BSs)  110  interconnected with each other via an IP network. The base stations discover their neighboring base stations by transmitting to each other an Inter-Access Network Signaling (IAS)-Neighbor Discovery Report message to report Access Network IDs (ANIDs—essentially IP addresses) of neighboring BSs as well as other UMB-related information about neighboring cells. UMB network  100  also includes an Access Gateway (AGW)  130  and a Session Reference Network Controller (SRNC)  140 . Access Gateway (AGW)  130  provides the point of Internet Protocol (IP) attachment to a Packet Data Network associated with Ultra Mobile Broadband (UMB) Radio Access Network (RAN)  100 . Session Reference Network Controller (SRNC)  140  hosts an Anchor Route for the UMB session. All BSs serving the AT must use the same SRNC. In addition, it is desirable that all BSs serving the AT be connected to the same Access Gateway (AGW). 
         [0029]    Femto devices are BSs that support a very small cell radius; typically, these Femto Devices will be deployed in a home environment which has poor coverage from the larger macro cell that is controlled by a BS. As shown in  FIG. 1 , Femto device  150  is disposed in macrocell  112  that is controlled by BS  110 . 
         [0030]    In a typical UMB Femto Device deployment, the Femto Device and the BS that controls the macrocell that the Femto Device resides in will need to be able to communicate via the UMB network protocols. In addition, in order for the UMB air interface to work properly (e.g. allow for smooth handoffs between the Femto Device and the macrocell), the Femto Device should connect to the same SRNC and AGW that the macrocell BS is connected to. 
         [0031]    Contemporarily, the IAS-Neighbor Discovery Report message only contain ANIDS and sector information of the immediate neighbors of the BS that transmits the IAS-Neighbor Discovery Report message. For a deployment of many Femto Devices over a large area (possibly serviced by many macro BSs), each Femto Device would need to be individually provisioned with the IP addresses of the SRNC and AGW used by the BS that controls the macrocell where the Femto Device resides. This makes for a very cumbersome Operations, Administration, and Maintenance (OA&amp;M) process, whereby a central management system must first geographically locate the Femto Device when the Femto device is initialized, identify the most likely macrocell that the Femto Device resides in, identify the BS that controls that macrocell, and then identify the SRNC and AGW that host that BS. The exists a need in the art for a more dynamic signaling method by which the Femto Device can attain the SRNC and AGW connection information directly from the BS that is controlling the macrocell that the Femto Device is residing in. 
         [0032]    The invention adds fields to the IAS-Neighbor Discovery Report message that will indicate the IP addresses of the SRNC and AGW that the sending entity, i.e., the BS uses. Using this enhanced message, the Femto Device can quickly learn the correct SRNC and AGW to use so as to ensure proper UMB functionality. The IAS-Neighbor Discovery Report message is triggered from the user&#39;s mobile station when the Femto Device is first configured. 
         [0033]      FIG. 2  schematically illustrates a configuration process for a Femto device as one embodiment according to the principles of the present invention. First, at step  210 , a Femto initialization and Authorization procession is performed in a Management system (not shown) for Femto device  150 . At step  212 , Femto device  150  transmits a Femto Pilot message to AT  120 . At step  214 , AT  120  senses the Femto pilot message transmitted from Femto device  150 . In response to the Femto pilot message, AT  120  transmits a UMB Pilot Report message. Note that BS  110  that controls macrocell  112  where Femto device  150  resides also transmits a macrocell Pilot message to AT  120  at step  212 . Therefore, the UMB Pilot Report message includes the pilot information of BS  110  that controls macrocell  112 . Femto device  150  will use this information to identify which base station to contact later. Femto device  150  then requests information regarding a sector Identity (ID) for the macrocell Pilot message by transmitting a UMB Sector ID Request message to AT  120  at step  216 . In response to the UMB Sector ID Request message, AT  120  transmits a UMB Sector ID Response message carrying the sector information, i.e., sector ID, for the macrocell Pilot message at step  218 . Subsequently, using the sector ID, Femto device  150  determines the Access Network ID for BS  110  that controls macrocell  112  where Femto device  150  resides, and requests neighbor information of BS  110  by transmitting a IAS-Neighbor Discovery Request message at step  220 . At step  222 , BS  110  responds to the IAS-Neighbor Discovery Request message by transmitting a IAS-Neighbor Discovery Report message containing the neighbor information of BBS  110 , and transmitting IP addresses of AGW  130  and SRNC  140  that BS  110  is connected to. Finally, Femto device  150  can connect to AGW  130  and SRNC  140  based on the IP addresses of AGW  130  and SRNC  140 . In this way, the Femto device can connect to the same SRNC and AGW that the BS is connected to. 
         [0034]      FIGS. 3A and 3B  schematically illustrate the format of the enhanced IAS-Neighbor Discovery Report message as an embodiment according to the principles of the present invention. The enhanced IAS-Neighbor Discovery Report message contains several information elements (IEs), such as message type, Correlation Identity (ID), Network ID, Neighbor Discovery Information, Sector Parameters, and UMB Network Connection information. The message may include multiple instances of these information elements. 
         [0035]    The Message Type Information Element (IE) is used to indicate the type of the message and occupies one octet (i.e., byte) in the IAS-Neighbor Discovery Report message. According to the 3GPP2 A.S0020, a hexadecimal value of “11” for the Message Type IE indicates that the message is an IAS-Neighbor Discovery Report message. 
         [0036]    The Correlation ID IE contains an ID that allows an entity to correlate a request-response pair and occupies six octets in the IAS-Neighbor Discovery Report message. The first octet of the Correlation ID IE is allocated to an Inter-Access Network Signaling (IAS) Information Element Identifier (IEI). A hexadecimal value of “02” is used to indicate that the current Information Element (IE) is the Correlation ID. The second octet of the Correlation ID IE is allocated to a length field, which indicates the number of octets following the length field in the current IE. Here, a hexadecimal value of “04” indicates that four octets are following the length field in the Correlation ID IE. The third to sixth octets of the Correlation ID IE are allocated to a correlation value, which is a manufacturer concern. 
         [0037]    The Network Identity IE contains the network identities of the sending and receiving Access Network Route Instances (ANRIs), i.e., the base stations, and occupies thirty-six octets. The first octet is allocated to the IAS IEI, which is a hexadecimal value of “03”. The second octet is allocated to the length field. The third through nineteenth octets are allocated to indicate the Network ID of the sender, in which the third octet is allocated to indicate the Network Identity Type of the sender. When the Network Identity Type of the sender is set to a hexadecimal value of “01”, the fourth through nineteenth octets are coded with the values of the Access network Identifier of the sender. The twentieth through thirty-sixth octets are allocated to indicate the network ID of the receiver, in which the twentieth octet is allocated to indicate the Network Identity Type of the receiver. When the Network Identity Type of the receiver is set to a hexadecimal value of “01”, the twenty-first through thirty-sixth octets are coded with the values of the Access network Identifier of the receiver. 
         [0038]    The Neighbor Discovery Information IE contains the information that the receiving ANRI needs to communicate with the sending ANRI, and to configure the air interface signaling information, such as neighbor fields Sector Parameters. The Neighbor Discovery Information IE occupies nineteen octets. The first octet is allocated to the IAS IEI, which is a hexadecimal value of “0C”. The second octet is allocated to the length field. The third through nineteenth octets are allocated to indicate the Neighbor Network Identity Type. When the Neighbor Network Identity Type is set to a hexadecimal value of “01”, the fourth through nineteenth octets are coded with the values of the Access network Identifier of the neighbor. 
         [0039]    The Sector parameters IE contains the encapsulated air interface Sector Parameter message, and occupies at least three octets. The first octet is allocated to the IAS IEI, which is a hexadecimal value of “0D”. The second octet is allocated to the length field. The rest octets are allocated to the Sector Parameter message. 
         [0040]    The UMB Network Connection Information IE contains network addresses of the AGW and the SRNC of the sending BS, and occupies seven or nineteen octets. The first octet is allocated to the IAS IEI of the UMB Network Connection Information IE. The second octet is allocated to the length field. In order to indicate the address of the AGW, the third octet is allocated to the AGW Address Type. When the AGW Address Type is set to a hexadecimal value of “01” to indicate Internet Protocol Version Four, the fourth through seventh octets are coded to indicate the AGW IPv4 address. When the AGW Address Type is set to a hexadecimal value of “02” to indicate Internet Protocol Version Six, the fourth through nineteenth octets are coded to indicate the AGW IPv6 address. Alternatively, in order to indicate the address of the SRNC, the k-th octet is allocated to the SRNC Address Type. When the SRNC Address Type is set to a hexadecimal value of “01” to indicate Internet Protocol Version Four, the k+1-th through k+4-th octets are coded to indicate the SRNC IPv4 address. When the AGW Address Type is set to a hexadecimal value of “02” to indicate Internet Protocol Version Six, the k+1-th through k+15-th octets are coded to indicate the SRNC IPv6 address. 
         [0041]    Accordingly, in the present invention, the central management system does not need to know the geographical location of the Femto device. It is advantageous for the Femto device and the macrocell BS to connect to the same SRNC and AGW, and the present invention provides a direct signaling method between the Femto device and the macrocell BS to share the geographical information of the Femto device. Note that this does not preclude the Femto device from sending information regarding the macrocell BS to the central management system for other purposes. 
         [0042]    While the present invention has been described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the present invention as defined by the following claims. In addition to the IP addresses of the AGW and the SRNC, other network information may also be added to the IAS-Neighbor Discovery Report message.