Abstract:
The present invention provides a relocation of an application-specific functionality for an application that a mobile terminal (mobile node) is executing. Entities that may provide application-specific functionalities that assist the application include a location-based server (that may be associated with a supplementary service provider functionality), a transcoder proxy, and a security gateway. The relocation of the application-specific functionality with a network layer-level handoff enables the mobile terminal to seamlessly execute an application that utilizes the media content from a content source that is supporting the mobile terminal before the handoff Subsequent to the handoff, the mobile terminal registers with a current access router in order to inform the current access router about application context information. In the exemplary embodiments, the access routers and the content source support the discovery of an entity that can support the application-specific functionality and the configuration of the application-specific functionality after the handoff.

Description:
“This application claims priority to provisional U.S. patent application Ser. No. 60/375,414 (“Proactive Seamless Service Provisioning in Mobile Networks Through Registering and Transferring of Application Context in a Proactive-Committing Manner”), filed Apr. 26, 2002.” 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the relocation of an application-specific functionality, such as a supplementary service provider functionality, for a mobile terminal during a network layer-level handoff. 
     BACKGROUND OF THE INVENTION 
     Providing seamless services is a critical issue for mobile networks. In the context of services supported by the Internet protocol (IP), seamless IP-layer connectivity is necessary as a mobile terminal hands off to a new access router with minimal disruption to the mobile terminal&#39;s Internet connectivity. There are several approaches to providing IP connectivity. First, the mobile IP protocol describes a mechanism that allows packets to be routed through the Internet to a new access router when the mobile terminal changes its point of attachment to the Internet from an old access router to the new access router. Also, after having established link-layer connectivity with the new access router, the mobile terminal engages in signaling the new access router in order to obtain its new care-of-address. When obtaining the new care-of-address the mobile terminal has acquired IP-level connectivity with the new access router so that the mobile terminal can transmit and receive packets with the new access router. A fast handoff protocol enables forming the new care-of-address while the mobile terminal is still attached to the old access router. As soon as the mobile terminal acquires link-layer connectivity with the new access router, the mobile terminal can transmit and receive packets with the new access router. 
     Moving the mobile terminal&#39;s point of attachment to the Internet from the current access router to the new access router may not suffice to provide seamless service if the mobile terminal&#39;s application requires additional features for packet transport such as transport quality of service (QoS), security, and header compression. These features need to be provided at the new point of mobile terminal&#39;s attachment to the Internet after IP-layer handoff. This can be achieved via context transfer framework. 
     Current approaches to a context transfer framework limit solutions to seamless IP-layer connectivity and do not address the service and business related aspects. In other words, ability to exchange packets with the Internet in an uninterrupted fashion in the light of handoffs as considered by current approaches, does not necessarily mean that the multimedia application on the mobile terminal will continue seamlessly. This is because, applications may make use of certain application-specific network functionalities, which may need to be relocated or provisioned concurrently with IP-layer handoffs. 
     For example, a mobile terminal (mobile node) may be accessing an Internet application that is provided by a content source such as line navigation, which depends upon the mobile terminal&#39;s geographical location. Typically, the content source uses a supplementary service provider functionality that is specific to the network serving the mobile terminal. In the case of a location service, for example, selecting the supplementary service provider functionality according to the serving network may be necessitated by the dependence of radio access technology that the mobile terminal is utilizing (global positioning satellites, time difference of arrival, angle difference of arrival, RF badges, and so forth) as well as by the physical wireless environment (e.g. indoor or outdoor). Moreover, the supplementary service provider functionality is accessing highly confidential data, namely the mobile terminal&#39;s location, and hence the supplementary service provider functionality has a special trust relationship with the administrative entity of the network domain that is serving the mobile terminal. 
     If the mobile terminal hands off to another administrative domain, either by migrating to another network operator that uses the same radio technology as the previous network operator or by switching to another radio access technology of another network operator, the current supplementary service provider functionality may not be able to provide mobile terminal&#39;s location information to customize the content from the content source to the mobile terminal. Even though the mobile terminal may experience seamless IP-network connectivity, an application that the mobile terminal is utilizing before the handoff may not he able to continue after the IP-level handoff because the content source does not have access to an appropriate supplementary service provider functionality. Hence, with the increasing importance of supporting enhanced services to a mobile terminal over the Internet, there is a need to support application-specific functionality in a seamless manner. 
     SUMMARY OF THE INVENTION 
     The aspects of the present invention provide a relocation of an application-specific functionality for an application that a mobile node such as a mobile terminal is executing. Entities that may provide application-specific functionalities that assist the application include a location tracking server (that may be associated with a supplementary service provider functionality), a transcoder proxy, and a security gateway. The relocation of the application-specific functionality with a network layer-level handoff (e.g. an IP-level handoff) enables the mobile terminal to seamlessly execute an application that utilizes the media content from a content source that is supporting the mobile terminal before the handoff Prior to the handoff, the mobile terminal registers with a current access router in order to inform the current access router about application context information. 
     In a first exemplary embodiment of the invention, preceding the handoff, the current access router informs a new access router about application context information that is indicative of the required application-specific functionality. Subsequently, the new access router discovers an entity that can support the application-specific functionality in the associated wireless network. The new access router also configures the application-specific functionality and informs the content source to continue the packet data stream to a new care-of address after the handoff and to utilize the configured application-specific functionality. It may also inform the mobile terminal about the address and characteristics of the configured application-specific functionality. 
     In another exemplary embodiment of the invention, the content source discovers the entity that can support the application functionality in the associated wireless network. Also, the content source configures the application-specific functionality. The content source may continue transmitting the packet data stream to the mobile terminal utilizing a new care-of address that is provided by the new access router. 
     In another exemplary embodiment of the invention, the new access router discovers the entity that can support the application functionality in the associated wireless network. The content source is provided information about the discovered entity, and the content source subsequently performs its part of configuration of the application-specific functionality. The content source may continue transmitting the packet data stream to the mobile terminal utilizing a new care-of address that is provided by the new access router. The mobile terminal may also be informed about the discovered entity, and the mobile terminal subsequently performs its part of configuration of the application-specific functionality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a first architecture supporting an application-specific functionality, such as a supplementary service provider functionality according to some embodiments of the invention; 
         FIG. 2  shows a second architecture supporting an application-specific functionality according to some exemplary embodiments of the invention; 
         FIG. 3  shows a messaging scenario in which an access router discovers and configures an application-specific functionality according to an embodiment of the invention; 
         FIG. 4  shows a messaging scenario in which a content source discovers and configures an application-specific functionality according to an embodiment of the invention; 
         FIG. 5  shows a messaging scenario in which a hybrid approach is utilized to discover and to establish an application-specific functionality according to an embodiment of the invention; and 
         FIG. 6  shows apparatus for a mobile terminal, an access router, and a content source in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an architecture  100  that supports an application-specific functionality, such as a supplementary service provider (SSP) functionality, in accordance with some embodiments of the invention (as will be discussed in the context of  FIGS. 3 ,  4 , and  5 ). In  FIG. 1 , a mobile node such as a mobile terminal  101   a  receives packets from a content source  103  through a path  161 , a border router (BR)  105 , a path  163 , a gateway router (GR)  107 , a path  165 , an access router (AR)  109 , and a wireless communications channel  151 . In the embodiments, paths  161 ,  163 , and  165  may utilize an Internet protocol (IP). The packets may support different types of content including audio, video, and multimedia formats. In the exemplary embodiments, the packets are transported through the Internet  130  that utilizes IP, although other embodiments may support other network layer protocols. 
     Mobile terminal  101   a  is served by a wireless network  120 , which is connected to Internet  130  through gateway router  107 . Access router  109  typically communicates to mobile terminal  101   a  through a base transceiver station (BTS) that may support different wireless technologies such as code division multiple access (CDMA), global system for mobile communications (GSM), and IEEE 802.11 (Wireless Local Area Networks Standards). 
     In the exemplary embodiments, a service that is provided to mobile terminal  101   a  may comprise the content generated by content source  103  in concert with a supplementary service functionality that is provided by a supplementary service provider (SSP)  115 . Supplementary service provider  115  serves a mobile terminal  101   a  when the mobile terminal  101   a  is located within network  120 . 
     The content from content source  103  may be dynamically modified according to information about mobile terminal  101   a  as determined by supplementary service provider  115 . With the exemplary embodiments shown in  FIGS. 3 ,  4 , and  5 , for example, content source  103  may use location information about mobile terminal  101   a  for location-dependent content in which mobile terminal  101   a  is provided driving instructions to a designated location. Location-based information may also be used to provide targeted advertisements to mobile terminal  101   a . Content source  103  communicates with supplementary service provider  115  through a path  171 , border router  105 , a path  173 , gateway router  107 , and a path  175 . 
     A supplementary service provider (e.g. SSP  115 ) is typically specific to a network (e.g. network  120 ) in which mobile terminal  101   a  is currently attached. With some embodiments, the utilized technology for the provision of the supplementary service functionality may be different for different networks (e.g. network  120  and network  140 ). With a location tracking supplementary service functionality, supplementary service provider  115  and supplementary service provider  117  may utilize time/angle difference of arrival, global positioning satellites (GPS), coarse tracking based on cell number, or indoor tracking using RF badges, depending upon the underlying radio technology and the physical environment of the associated network. (For example, network  120  may support analog service while network  140  supports third generation digital service. Or, network  120  may be outdoor cellular network while network  140  could be indoor wireless LAN.) The difference of radio technologies and physical environments may necessitate that supplementary service providers  115  and  117  utilize different location algorithms.) Also, a network administrator of network  120  or  140  may not be able to utilize an associated supplementary service provider functionality when mobile terminal  101   a  is not located in the administrator&#39;s network domain. 
     Mobile terminal  101   a  may charge its location within network  120  (as characterized by mobility) and may be subsequently served by a network  140  if mobile terminal  101   a  migrates into network  140 . Network  140  may serve a different geographical area and may utilize a different wireless technology than network  120 . If mobile terminal  101   a  moves into network  140  (as shown as a mobile terminal  101   b ) continued service needs to utilize a different supplementary service provider, thus necessitating a change from supplementary service provider  115  to supplementary service provider  117 . Some embodiments of the invention (corresponding to  FIGS. 3 ,  4 , and  5 ) reconfigure the service so that supplementary service provider  117  provides the supplementary service functionality after the completion of an IP-level handoff  102 . After handoff  102  mobile terminal  101   b  receives packets from content source  103  through path  161 , border router  105 , a path  167 , a gateway router  111 , a path  169 , an access router  113 , and a wireless communications link  153 . Content source  103  communicates with supplementary service provider  117  through, path  171 , border router  105 , a path  177 , gateway router  111 , and a path  179 . 
       FIG. 2  shows an architecture  200  supporting an application-specific entity (ASE)  215  or  217  according to exemplary embodiments of the invention that are shown in  FIGS. 3 ,  4 , and  5 . Application-specific entities  215  and  217  provide an application-specific functionality. An application-specific functionality may support fundamental functionality such as security functionality and transcoding functionality. With architecture  200 , application-specific entity  215  intervenes between communicating endpoints (e.g. mobile terminal  101   a  and content source  103 ). Application-specific entities may support a packet data stream from content source  103  (e.g. a transcoder) or packets from mobile terminal  101   a  and content source  103  (e.g. a security gateway). Content source  103  communicates to  101   a  through a path  271 , border router  105 , a path  273 , gateway router  107 , a path  275 , application-specific entity  215 , a path  277 , access router  109 , and wireless communications channel  151 . 
     With architechure  200 , applicationspecihe entity  215  may be a transcoding function that supports format conversion, data size reduction and customizing multimedia web content such as images and video. The transcoding function enables transmission between communication endpoints (e.g. mobile terminal  101   a  and content source  103 ) to be delivered over low bandwidth and error-prone wireless links and to be processed according to capabilities of mobile terminal  101   a . If for example, mobile terminal  101   a  initiates a streaming video application from a third generation (3G) cellular coverage area (corresponding to network  120 ) and hands off into a second generation (2G) cellular coverage area (e.g. network  140 ), an appropriate transcoding function (e.g. application-specific entity  217 ) may need to be configured in order to match the bandwidth constraints of network  140 . Moreover, application specific entity (such as a transcoding entity)  215  may not be accessible because packets may be directly transmitted from content source  103  and network  140 . After handoff  102 , content source  103  communicates with mobile  101   b  (as designated after handoff  102 ) through path  271 , border router  105 , a path  279 , application specific entity  217 , a path  281 , gateway router  111 , a path  283 , access router  113 , and wireless communications link  153 . 
     Application-specific entity  215  may also support a security function. Security associations may be at an application level or at a network level (e.g. IP). With an IP-level security association,  215  may utilize IPsec, in which a security association can be established using either an Internet Key Exchange (IKE) protocol or a manual configuration procedure. IPsec tunneling encapsulates the original packet inside a new packet. 
     An IPsec security association may be established between security gateways (as may be supported by application-specific entity  215  and application-specific entity  217 ) and communication endpoints (such as content source  103 ). In such a case, mobile terminal  101   a  relies on a security gateway (application-specific entity  215 ) when attached to access router  109  (serving network  120 ). Packets from mobile terminal  101   a  traverse between application-specific entity  215  and content source  103  in a secure manner. When mobile terminal  101   a  (designated as  101   b  after handoff  102 ) handoffs from network  120  to network  140 , a new IPsec security association is established between application-specific entity  217  and content source  103 . 
       FIG. 3  shows a messaging scenario in which access router  113  discovers and configures an application-specific functionality according to a first exemplary embodiment of the invention. With a transactions procedure  301 , mobile terminal  101   a  and content source  103  set up a data session in order to initiate the packet data stream from current content source  103  to mobile terminal  101   a  through current access router  109 . Typically, current access router  109  is unaware of specific characteristics of end-user applications being executed by mobile terminal  101   a . In the embodiment, hyper text transfer protocol (in accordance with Internet Engineering Task Force RFC 2616) is utilized, although other embodiments may utilize session initiation protocol (SIP in accordance with Internet Engineering Task Force RFC 2543) or other protocols. The content of the HTTP or SIP messages that are exchanged between mobile terminal  101   a  and content source  103  are typically not visible to current access router  109  during transaction  301 . Consequently, a registration procedure  303  is executed by mobile terminal  101   a  in order to explicitly register application context information with current access router  109 . The application context information indicates the required application-specific functionality. In the embodiment, registration procedure  303  utilizes Internet control message protocol (ICMP that is specified in Internet Engineering Task Force RFC 792), user datagram protocol (UDP), transmission control protocol (TCP), or any standard method of message transfer between nodes in an IP network. Other embodiments may utilize other protocols such as hypertext transfer protocol. 
     The format of the application context information is dependent upon the specific application. In the embodiment, the application context information comprises an content profile and a media description. Some exemplary applications include location service applications, transcoder service applications, and security gateway applications. With a location service application, the application context information may describe a need for a location server and a content source (e.g. content source  103 ) that is authorized to receive location information. With a transcoder service application, the application context information may describe a media coding scheme, required bandwidth, and quality of service (QoS) for transmission of video content. With a security gateway application, the application context information may describe a need for a security gateway, parameters for security processing, and an identity of the content source (e.g. content  103 ). 
     A packet data stream  305  may be generated by content source  103  in order to support the application as established in transaction procedure  301  and forwarded by current access router  109  to mobile terminal  101   a  as packet data stream  305 . Packets associated with packet data stream  305  are typically delivered to mobile terminal  101   a  utilizing a care-of address (Internet Engineering Task Force RFC 3220 and draft-ietf-mobileip-ipv6-16.txt) if mobile terminal  101   a  is not located in a region that is served by its home agent such as a router. The care-of address is the termination point of a tunnel toward a mobile node such as mobile terminal  101   a  for packets forwarded to mobile terminal  101   a  when mobile terminal  101   a  is not located in its home serving area. 
     If mobile terminal  101   a  approaches the boundary between network  120  and network  140 , current access router  109  may determine that an IP-level handoff may occur. In the exemplary embodiment, a base transceiver station that is serving mobile terminal  101   a  and that is associated with access router  109  measures the signal strength of mobile terminal  101   a  (corresponding to the reverse/forward direction or the uplink/downlink). If the signal strength is below a signal threshold, the base transceiver station notifies current access router  109  about the impending handoff When current access router  109  determines that an IP-level handoff may occur, current access router  109  provides new access router  113  with the application context information by sending an application context transfer message  307  to new access router  113 . The embodiment can utilize ICMP, UDP, TCP, stream control transmission protocol (SCTP) (Internet Engineering Task Force RFC 2960), or any method for transferring messages between two nodes in an IP network. Consequently, new access router  113  performs a discovery and configuration procedure  311  in order to find supplementary service provider  117  or application-specific entity  217  that can provide the application-specific functionality in network  140  in order to support the media content being utilized by mobile terminal  101   b  (as designated for the mobile terminal after a handoff  309 ). In the embodiment, new access router  113  can discover supplementary service provider  117  or application-specific entity  217  by using a static configuration (e.g. accessing a data structure that is maintained at new access router  113  in which an address of supplementary service provider  117  or application-specific entity  217  is mapped to the required functionality as deduced from the received application context), accessing a directory agent that may be external to new access router  113 , or sending a multicast query within network  140  that contains the profile of required application-specific functionality. New access router  113  may utilize service location protocol (Internet Engineering Task Force RFC 2165) with the inclusion of a proprietary or standardized field (service profile) that designates the type of application-specific functionality that is required (e.g. transcoder or location-based service). With the multicast query, supplementary service provider  117  or application-specific entity  217  responds to the query if supplementary service provider  117  or application-specific entity  217  can support mobile terminal  101   b  in network  140 . 
     New access router  113  also configures the application specific functionality with supplementary service provider  117  or application-specific entity  217 . With a location-based supplementary service provider functionality, the application context information may indicate that location service is required and may identify that content source  103  is authorized to receive location information about mobile terminal  103 . New access router  113  may authorize supplementary service provider  117  to provide information about mobile terminal  102   b  to content source  103 . New access router  113  can utilize protocols such as Internet control message protocol (ICMP), user datagram protocol (UDP), and transmission control protocol (TCP) to issue a command to supplementary service provider  117 . 
     With a message  313 , new access router  113  provides information about supplementary service provider  117  or application-specific entity  217  to content source  103 . For a location tracking supplementary service functionality, message  313  may include an address of supplementary service provider  117  and a new-care of address (associated with mobile terminal  101   b ) to content source  103  so that content source  103  may modify content that is dependent upon the location of mobile terminal  101   b  and deliver the content to mobile terminal  101   b . Delivery of content commences with a packet data stream  315  when mobile terminal  101   a  handoffs to network  140  as a result of handoff trigger  309 . 
       FIG. 4  shows a messaging scenario in which content source  103  discovers and configures an application-specific functionality according to another exemplary embodiment of the invention. With a transactions procedure  401 , mobile terminal  101   a  and content source  103  set up a data session in order to initiate the packet data stream from current content source  103  to mobile terminal  101   a . Typically, current access router  109  is unaware of specific characteristics of end-user applications being executed by mobile terminal  101   a . In the embodiment, hyper text transfer protocol is utilized, although other embodiments may utilize session initiation protocol or other protocols. The content of messages, such as HTTP or SIP messages, that are exchanged between mobile terminal  101   a  and content source  103  are typically not visible to current access router  109  during transaction  401 . Consequently, a registration procedure  403  is executed by mobile terminal  101   a  in order to explicitly register application context information with current access router  109 . In the embodiment, registration procedure  403  utilizes Internet control message protocol, user datagram protocol (UDP), transmission control protocol (TCP), or any standard method of message transfer between nodes in an IP network. Other embodiments may utilize other protocols such as hypertext transfer protocol. 
     A packet data stream  405  is generated by content source  103  in order to support the application as established in transaction procedure  401  and forwarded by current access router  109  to mobile terminal  101   a  as packet data stream  405 . Packets associated with packet data stream  405  are typically delivered to mobile terminal  101   a  utilizing a care-of address if mobile terminal  101   a  is not located in a region that is served by its home agent (router). The care-of address is the termination point of a tunnel toward mobile terminal  101   a  for packets forwarded to mobile terminal  101   a  when mobile terminal  101   a  is not located in its home serving area. 
     If mobile terminal  101   a  approaches the boundary between network  120  and network  140 , current access router  109  may determine that an IP-level handoff may occur. In the embodiment, a base transceiver station that is serving mobile terminal  101   a  and that is associated with access router  109  measures the signal strength of mobile terminal  101   a  (corresponding to the forward/reverse direction or the downlink/uplink). If the signal strength is below a signal threshold, the base transceiver station notifies current access router  109  about the impending handoff. When current access router  109  determines that an IP-level handoff may occur, current access router  109  provides new access router  113  with the application context information by sending an application context transfer message  407  to new access router  113 . The embodiment can utilize ICMP, UDP, TCP, stream control transmission protocol (SCTP) (Internet Engineering Task Force RFC 2960), or any method for transferring messages between two nodes in an IP network. New access router  113  processes the application context information. The embodiment, for example, may determine the need for transcoding service if bandwidth capabilities of network  140  cannot support the complete bandwidth requirements of the content. In such a case, new access router  113  may compare bandwidth and QoS requirements that are specified in the application context information with the corresponding characteristics of the IP connection between mobile terminal  101   b  and new access router  113 . New access router may determine if application-specific functionality such as transcoding functionality is needed. 
     New access router  113  notifies content source  103  about the need for application-specific functionality (e.g. transcoding functionality) as well as information such as a session identity, a new care-of-address for mobile terminal  101   b , and the characteristics of the IP connection between mobile terminal  102   b  and new access router  111  by sending a message  411 . Consequently, content source  103  initiates a discovery and configuration procedure  413 . 
     Content source  103  performs discovery and configuration procedure  413  in order to find supplementary service provider  117  or application-specific entity  217  that can provide the application-specific functionality to support the media content being utilized by mobile terminal  101   b  (as designated for the mobile terminal after a handoff  409 ). In the exemplary embodiment, content source  103  can discover supplementary service provider  117  or application-specific entity  217  by using a static configuration (e.g. accessing a data structure that is maintained at content source  103  in which an address of supplementary service provider  117  or application-specific entity  217  is mapped to the required application-specific functionality), accessing a directory agent that may be external to content source  103 , or sending a multicast query that contains the profile of the required application-specific functionality. Content source  103  may utilize the service location protocol with the inclusion of a proprietary or standardized field (service profile) that designates the type of application-specific that is required (e.g. transcoder or location-based service). With the multicast query, supplementary service provider  117  or application-specific entity  217  responds to the query if supplementary service provider  117  or application-specific entity  217  can support mobile terminal  101   b  in network  140 . 
     Content source  103  configures the application-specific functionality (e.g. transcoding functionality) by inviting supplementary service provider  117  or application-specific entity  217  to the session. In the exemplary embodiment, content source  103  sends a SIP INVITE message, in accordance with the session initiation protocol, to supplementary service provider  117  or application-specific entity  217  in order to provide information such as media and bandwidth information and the new care-of address of mobile terminal  101   b . Content source  103  consequently sends a SIP INVITE message to mobile terminal  102   b  at the new care-of address with appropriate information (e.g. information about the transcoded packet stream) in order to complete the configuration procedure. In the other embodiment, the content source  103  may send a confirm message  415  to mobile terminal  102   b  through new access router  113  rather than send the SIP INVITE message to mobile terminal  102   b.    
     A packet data stream  417  (corresponding to the media transfer) is initiated from content source  103  to mobile terminal  101   b . For an application-specific functionality such as transcoding, the media transfer is transmitted to application-specific entity  217  (acting as a transcoding proxy) and from application-specific entity  217  to mobile terminal  103  using the new care-of address of mobile terminal  101   b.    
       FIG. 5  shows a messaging scenario in which a hybrid approach is utilized to discover and to configure an application-specific functionality according to another exemplary embodiment of the invention. With a transactions procedure  501 , mobile terminal  101   a  and content source  103  set up a data session in order to initiate a packet data stream from current content source  103  to mobile terminal  101   a . Typically, current access router  109  is unaware of specific characteristics of end-user applications being executed by mobile terminal  101   a . In the embodiment, hyper text transfer protocol is utilized, although other embodiments may utilize session initiation protocol or other protocols. The content of the HTTP or SIP messages that are exchanged between mobile terminal  101   a  and content source  103  are typically not visible to current access router  109  during transaction  501 . Consequently, a registration procedure  503  is executed by mobile terminal  101   a  in order to explicitly register application context information with current access router  109 . In the embodiment, registration procedure  503  utilizes Internet control message protocol, user datagram protocol (UDP), transmission control protocol (TCP), or any standard method of message transfer between nodes in an IP network Other embodiments may utilize other protocols such as hypertext transfer protocol. 
     A packet data stream  505  is generated by content source  103  in order to support the application as established in transaction procedure  501  and forwarded by current access router  109  to mobile terminal  101   a  as packet data stream  505 . Packets associated with packet data stream  505  are typically delivered to mobile terminal  101   a  utilizing a care-of address if mobile terminal  101   a  is not located in a region that is served by its home agent (router). The care-of address is the termination point of a tunnel toward mobile terminal  101   a  for packets forwarded to mobile terminal  101   a  when mobile terminal  101   a  is not located in its home serving area. 
     If mobile terminal  101   a  approaches the boundary between network  120  and network  140 , current access router  109  may determine that an IP-level handoff may occur. In the embodiment, a base transceiver station that is serving mobile terminal  101   a  and that is associated with access router  109  measures the signal strength of mobile terminal  101   a  (corresponding to the forward/reverse direction or the downlink/uplink). If the signal strength is below a signal threshold, the base transceiver station notifies current access router  109  about the impending handoff. When current access router  109  determines that an IP-level handoff may occur, current access router  109  provides new access router  113  with the application context information by sending an application context transfer message  507  to new access router  113 . The embodiment can utilize ICMP, UDP, TCP, stream control transmission protocol (SCTP) (Internet Engineering Task Force RFC 2960), or any method for transferring messages between two nodes in an IP network. New access router  113  processes the application context information. 
     Consequently, new access router  113  performs a discovery procedure  509  in order to find supplementary service provider  117  or application-specific entity  217  that can provide the application-specific functionality to support the media content being utilized by mobile terminal  101   b  (as designated for the mobile terminal after a handoff  511 ). In the embodiment, new access router  113  can discover supplementary service provider  117  or application-specific entity  217  by using a static configuration (e.g. accessing a data structure that is maintained at new access router  113  in which an address of supplementary service provider  117  or application-specific entity  217  is mapped to the profile of the required application-specific functionality), accessing a directory agent that may be external to new access router  113 , or sending a multicast query that contains the profile of the required application-specific functionality. New access router  113  may utilize the service location protocol with the inclusion of a proprietary or standardized field (service profile) that designates the type of application-specific that is required (e.g. transcoder or location-based service). With the multicast query, supplementary service provider  117  or application-specific entity  217  responds to the query if supplementary service provider  117  or application-specific entity  217  can support mobile terminal  101   b  in network  140 . 
     With a variation of the embodiment, current access router  109  may perform discovery procedure  509  in order to find supplementary service provider  117  or application-specific entity  217  that can provide the application-specific functionality in network  140 . In such a case, current access router  109  provides information about application-specific functionality to content source  103 . 
     Subsequent to new access router  113  discovering supplementary service provider  117  or application-specific entity  217  that can support the application-specific functionality, new access router sends a message  513  to content source  103  with information about the application-specific functionality that was discovered during procedure  509 . New access router  113  also sends a message  521  to mobile terminal  101   b  with information about the application-specific functionality that may include the address of application-specific entity  217  or supplementary service provider  117 . Mobile terminal  101   b  may authorize application-specific entity  217  or supplementary service provider  117  to provide the application-specific functionality for its applications. Also, mobile terminal  101   b  may also create any states that are needed for availing the functionality. Mobile terminal  101   b  completes the configuration with network  140  with an establishment procedure  523  and confirms the configuration by sending a confirm message  525  to new access router  113 . Content source  103  completes the configuration with supplementary service provider  117  or application-specific entity  217  with a procedure  515 . For example, for an application-specific functionality corresponding to a security gateway, content source  103  may build a security association with the security gateway (e.g. application-specific entity  217 ). 
       FIG. 6  shows apparatus for mobile terminal  105 , an access router  610  (e.g. current access router  109  and new access router  113 ), a content source  620  (e.g. content source  103 ) in accordance with the exemplary embodiments of the invention. Mobile terminal  105  comprises a processor  601 , a communications interface  603 , and a memory  605 . Mobile terminal  105  communicates over wireless channel  108  through communications interface  603 . Processor  601  executes a software program from memory  605  in accordance with the message scenarios shown in  FIGS. 3 ,  4 , and  5 . 
     Access router  610  comprises a processor  611 , ports  613  and  615 , and a memory  617 . Processor  611  communicates with a base transceiver station through port  613  through an IP path  650  and with content source  620  through port  615  and an IP path  651 . Processor  611  executes a software program from memory  617  in accordance with the message scenarios shown in  FIGS. 3 ,  4 , and  5 . 
     Content source  620  comprises a processor  621 , a port  623 , a program memory  625  and a media memory  627 . Processor  621  communicates with access router  610  through port  623  and IP path  651 . Processor  621  executes a software program from program memory  625  in accordance with the message scenarios shown in  FIGS. 3 ,  4 , and  5 . Also, processor  621  generates a packet data stream by accessing media memory  627  in order to obtain the media content that is being played for the data session. 
     As can be appreciated by one skilled in the art, a computer system with an associated computer-readable medium containing instructions for controlling the computer system can be utilized to implement the exemplary embodiments that are disclosed herein. The computer system may include at least one computer such as a microprocessor, digital signal processor, and associated peripheral electronic circuitry. 
     While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.