Patent Publication Number: US-9426719-B2

Title: Anchoring services of a mobile station attached to a first service domain at a home agent in a second service domain

Description:
RELATED APPLICATIONS 
     This application is a continuation of and claims priority to U.S. patent application Ser. No. 13/055,260 filed Jan. 21, 2011, published as US 2011-0122824 on May 26, 2011 and issued as U.S. Pat. No. 9,042,297 on May 26, 2015, which is a National Stage Entry and claims priority to PCT Application No. PCT/US2009/051393 filed Jul. 22, 2009, published as WO 2010/011740 on Jan. 28, 2010, which claims the benefit of priority from U.S. Provisional Application No. 61/083,413, filed Jul. 24, 2008, the disclosures of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     Various wireless access technologies have been proposed or implemented to enable mobile stations to perform communications with other mobile stations or with wired terminals coupled to wired networks. Examples of wireless access technologies include GSM (Global System for Mobile communications) and UMTS (Universal Mobile Telecommunications System) technologies, defined by the Third Generation Partnership Project (3GPP); and CDMA 2000 (Code Division Multiple Access 2000) technologies, defined by 3GPP2. 
     As part of the continuing evolution of wireless access technologies to improve spectral efficiency, to improve services, to lower costs, and so forth, new standards have been proposed. One such new standard is the Long Term Evolution (LTE) standard from 3GPP, which seeks to enhance the UMTS wireless network. 
     Dual-mode mobile stations can perform access using different types of wireless access networks, such as a legacy HRPD (High Rate Packet Data) wireless access network (as defined by CDMA 2000) or a E-UTRAN (Evolved UMTS Terrestrial Radio Access Network, as defined by 3GPP). The E-UTRAN wireless access network allows for access of 4G (fourth generation) wireless services, such as those provided by LTE. 
     As service operators evolve from legacy wireless access networks to 4G networks, such service operators typically have to support subscriber access at both types of networks. When a mobile station (such as a dual mode mobile station) attaches to an E-UTRAN wireless access network, for example, services provided in the legacy network may no longer be available to the mobile station. 
     SUMMARY 
     In general, a technique or mechanism is provided to allow anchoring of the services in a home network of the mobile station even when the mobile station is attached to a wireless access network of a different service domain. 
     Other or alternative features will become apparent from the following description, from the drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-3  illustrate portions of different networks in accordance with one or more embodiments; and 
         FIG. 4  is a block diagram of components in a node of a first service domain and a home agent node in a second service domain, according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of some embodiments. However, it will be understood by those skilled in the art that some embodiments may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. 
     Various services can be provided to a mobile station by a home service domain of the mobile station. Examples of such services include an accounting/billing service; a gaming service; a push-to-talk service; an instant conferencing or messaging service; a calendaring service; a location-based service (e.g., find the nearest store or other location); a presence service (e.g., service that follows the subscriber&#39;s movements); broadcast and multicasting services (e.g., relating to Internet TV); and so forth. 
     Thus, when the mobile station is attached to a wireless access network of the mobile station&#39;s home service domain, such services can be provided to the mobile station. In one example embodiment, the home service domain of the mobile station includes an HRPD (High Rate Packet Data) wireless access network, as defined by 3GPP2, to support wireless access by the mobile station. The HRPD wireless access network is considered to be a legacy wireless access network. The home service domain in this example is considered a legacy service domain that supports services according to an older standard, such as the 3GPP2 CDMA 2000 standard. A “service domain” refers to an arrangement of network nodes associated with one or more service operators to provide wireless access and other services to a mobile station. 
     New wireless technologies are being developed, with one such new technology 10 being the Long Term Evolution (LTE) technology from 3GPP. The LTE network uses E-UTRAN as the wireless access technology for the mobile station to access the LTE network. In this example, LTE defines a second service domain that is of a different type than the home (or legacy) service domain. 
     Although reference is made to the HRPD and LTE standards above, it is noted that in alternative embodiments other types of service domains can be employed. 
     An issue associated with a mobile station that is attached to the E-UTRAN wireless access network is that the mobile station tends to follow LTE procedures and protocols, which may cause the mobile station to be anchored at a node in the LTE service domain. However, anchoring the mobile station in the LTE service domain means that the mobile station may no longer be able to access various services provided by the home service domain. 
     In accordance with some embodiments, to address the foregoing issue, a mechanism is provided to anchor a session of the mobile station at a node in the home service domain of the mobile station, even if the mobile station is attached to the E-UTRAN wireless access network (in a different service domain). By anchoring the mobile station at the node in the home service domain, services of the home service domain can be made available to the mobile station even though the mobile station is located in a different service domain. 
     In some embodiments, the node of the home service domain at which the session of the mobile station is anchored is a home agent as defined by either Proxy Mobile IPv4 (Internet Protocol version 4) or Proxy Mobile IPv6 (Internet Protocol version 6). Proxy Mobile IPv6 is defined by Request for Comments (RFC) 5213, entitled “Proxy Mobile IPv6,” dated August 2008. Proxy Mobile IPv4 is defined by K. Leung et al., Internet-Draft, entitled “WiMAX Forum/3GPP2 Proxy Mobile IPv4,” draft-leung-mip4-proxy-mode-10.txt, dated November 2008. 
     A home agent, as defined by Mobile IPv4 or IPv6, is a router on a mobile station&#39;s home network with which the mobile station has registered its current care-of address. In Proxy Mobile IPv6, the functionality of the home agent is provided in a local mobility anchor (LMA), which provides the functionalities of the home agent, as well as additional capabilities for supporting the Proxy Mobile IPv6 protocol. Thus, as used here, “home agent” refers to either a Mobile IP home agent or a Proxy Mobile IPv6 local mobility anchor. 
     Various different embodiments for anchoring the services of the mobile station at the home agent of the mobile station while the mobile station is attached to a different service domain are provided.  FIG. 1  illustrates a first solution according to an embodiment. In  FIG. 1 , two service domains are illustrated, including an LTE service domain  100  and a legacy service domain  102 . In the example of  FIG. 1 , the legacy service domain  102  uses HRPD wireless access technology with a core network defined by 3GPP2. 
     In the legacy service domain  102 , a wireless access network  104  includes an HRPD base transceiver station (BTS)  106 , and an access network (AN) node  108  that is attached to an AAA (authentication, authorization, and accounting) server  110  for performing authentication, authorization, and accounting tasks when a mobile station attaches to the wireless access network  104 . 
     The wireless access network  104  is connected to a PDSN (packet data serving node)  112  that provides access to an external packet data network such as the Internet, an intranet, or an application server. The PDSN  112  is a component of the CDMA 2000 network, and acts as a connection point between a wireless access network and the external packet data network. 
     The legacy service domain  102  also includes a home agent (HA)  116 , which enables the creation and maintenance of a binding between a mobile station&#39;s home address and its care-of address (the address used by the mobile station when it is attached to a visited network). The home agent manages the services provided to the mobile station, including 3GPP2 services provided by a 3GPP2 service network  118 . The 3GPP2 service network includes a service provider AAA server  120  to perform authentication, authorization, and accounting services when services of the 3GPP2 service network  118  are accessed by a mobile station. 
     The LTE service domain  100  includes an E-UTRAN wireless access network  120  to allow for wireless access by mobile stations, including a mobile station  130 . In addition, the LTE service domain  100  includes a serving gateway (SGW) that routes and forwards user data packets to a PDN (packet data network) gateway  126 . The PDN gateway  126  provides connectivity from the mobile station to an external packet data network by being the point of exit and entry of data traffic for the mobile station. The serving gateway is the anchor point for intra-3GPP mobility, as the mobile station  130  moves to different access points in the E-UTRAN wireless access network  120  that causes different SGWs to be selected. 
     The terms “serving gateway” and “packet data network gateway” can also be applied to other types of service domains (other than the LTE service domain). More generally, a packet data network gateway can refer to any point that establishes connectivity between a service domain and an external packet data network. A serving gateway can refer to any node that manages mobility of a mobile station within a service domain. 
     Another entity in the LTE service domain  100  is a mobility management entity (MME)  122 , which is a control node that provides various control services for a mobile station. Examples of such services include tracking the mobile station, providing a paging procedure for the mobile station, and so forth. The MME  122  is also involved in bearer activation and deactivation process, and is responsible for choosing the SGW for the mobile station at the time that the mobile station initially attaches to the E-UTRAN wireless access network  120 . 
     In accordance with the embodiment shown in  FIG. 1 , a link  128  is provided between the SOW  124  and the home agent  116  to allow the mobile station  130  attached to the E-UTRAN wireless access network  120  to be anchored by the home agent  116  (rather than be anchored at a node in the LTE domain  100 ). In this manner, the 30PP2 services provided by network  118  in the legacy service domain  102  can continue to be available to the mobile station  130  that is attached to the E-UTRAN wireless access network  120 . 
     There are two contexts in which the mobile station  130  can be anchored by the home agent  116  of the legacy service domain  102 . In a first context, the mobile station  130  is a dual mode mobile station that is able to attach either to the HRPD wireless access network  104  of the legacy service domain  102 , or to the E-UTRAN wireless access network  120  of the LTE service domain  100 . In a second context, the mobile station  130  can be an LTE-only mobile station that is able to attach only to the E-UTRAN wireless access network  120 . 
     When the mobile station  130  initially attaches to the E-UTRAN wireless access network  120 , the mobile station  130  performs access authentication based on E-UTRAN access procedures. As part of this access authentication process, the SOW  124  receives user information, including the home agent IP address (the IP address of the home agent  116 ) associated with the mobile station  130 . Other parameters of the user information received by the SOW  124  can include a user NAI (network access identifier), supported APNs (access point names, which are names used to identify bearer services), a user profile, mobility security association parameters, and so forth. 
     Upon receipt of the user information, the SOW  124  sends (at  150 ) a registration request, which can be a proxy RRQ (registration request) as defined by Proxy Mobile IPv4, on behalf of the mobile station  130  to the home agent  116  over the link  128  between the SOW  124  and home agent  116 . Note that the SOW  124  has the IP address of the home agent  116  since the SOW  124  has received the IP address of the home agent as part of the mobile station access authentication process. Upon receipt of the proxy RRQ from the SOW  124  over the link  128  (which can be a link that supports proxy mobile IPv4), the home agent  116  registers the mobile station&#39;s session. In addition, the home agent  116  allocates (at  152 ) an IP address for the session that the mobile station can use. 
     The home agent  116  then sends (at  154 ) a registration response message (e.g., proxy RRP) back to the SGW  124  over the link  128 . The proxy RRP message contains the allocated IP address for the mobile station. In response to the proxy RRP message, the SGW  124  follows the E-UTRAN access procedures to deliver (at  156 ) the IP address to the mobile station  130  through the E-UTRAN wireless access network  120 . 
     It is noted that from the perspective of the home agent  116 , the SGW  124  appears to be a PDSN similar to PDSN  112  in the legacy service domain  102 . 
     Whenever the mobile station moves across E-UTRAN wireless access network  120  (e.g., moves between different base stations), it is possible that a transfer from a source SGW to a target SGW would have to be performed. For an inter-SOW transfer, the system according to some embodiments ensures that the target SGW will receive the IP address of the mobile station&#39;s home agent ( 116 ), such that the target SGW can issue a proxy RRQ to the home agent  116  to cause the home agent  116  to assign the same IP address to the mobile station to maintain mobility and access to the 3GPP2 services infrastructure. 
       FIG. 2  illustrates an arrangement that supports at least one other embodiment. In this second embodiment, instead of establishing a link  128  ( FIG. 1 ) between the SGW  124  and the home agent  116 , a link  202  is established between the PDN gateway  126  and the home agent  116 . The nodes illustrated in  FIG. 2  are the same nodes as illustrated in  FIG. 1 . The link  202  supports Proxy Mobile IPv4 and IP-in-IP tunneling between the PDN gateway  126  and the home agent  116 . IP-in-IP tunneling refers to encapsulating one IP packet in the payload of another IP packet. 
     In the second solution that employs the arrangement of  FIG. 2 , the PDN gateway  126  supports proxy Mobile IPv4 mobile access gateway (MAG) or proxy mobility agent (PMA) functionality. PMA manages the mobility related signaling for a mobile station that is attached to the MAG. The MAG performs mobility management on behalf of the mobile station. The MAG also tracks the mobile station&#39;s movements so that handover between the MAG and another MAG can be performed when the mobile station crosses between coverage areas of the respective MAGs. 
     After the mobile station performs access authentication based on E-UTRAN access procedures, the SGW  124  receives the user information including the IP address of the PDN gateway  126  and other parameters as discussed above in connection with  FIG. 1 . Upon receiving such information, the SGW  124  follows 3GPP procedures to establish an IP session for the mobile station at the PDN gateway  126 . This can be accomplished by using a binding procedure ( 210 ) as defined by Proxy Mobile IPv6, such as by sending a proxy binding update (PBU) message that requests an IP address for the mobile station. 
     When the PDN gateway  126  receives the proxy binding update message, the PDN gateway  126  either by using out-of-band signaling or static configuration, finds the IP address of the home agent that is supposed to anchor the IP session for the mobile station. Out-of-band signaling can be performed by accessing an AAA server to select the home agent. Alternatively, the PDN gateway  126  may be provided with multiple home agents from which the PDN gateway  126  can make a selection (for load balancing purposes). As yet another alternative, static configuration is provided, where the PDN gateway  126  has to use a particular home agent. 
     Upon obtaining the IP address of the home agent  116 , the PDN gateway  126  sends (at  212 ) a proxy RRQ message to the home agent  116  to allocate an IP address to the mobile station and to create a binding for the user session to a proxy care-of-address (CoA) that is terminated at the PDN gateway  126 . 
     When the home agent  116  receives the proxy RRQ message, the home agent  116  validates the proxy RRQ message and if successful, the home agent  116  will allocate (at  214 ) an IP address for the session that is returned (at  216 ) to the PDN gateway  126  in a proxy RRP message. The home agent  116  also creates a binding for the user, its home address, and the proxy care-of-address that belongs to the PDN gateway  126 . 
     When the PDN gateway  126  receives the proxy RRP message from the home agent  116  with the IP address of the mobile station included, the PDN gateway  126  sends a proxy binding acknowledgement (PBA) to the SGW  124  (as part of the binding procedure  210 ) with the assigned home IP address, along with other parameters such as the IPv6 home network prefix (HNP). The HNP is assigned to an interface of a mobile station to the Proxy Mobile IP domain, and the HNP can be used to derive an address of the interface. 
     The PDN gateway  126  updates a mobile station&#39;s current BCE (binding cache entry) with the home agent IP address. It is possible to create a separate binding that is linked to the mobile station&#39;s proxy BCE. 
     When the SGW  124  receives the proxy binding acknowledgment message from the PDN gateway  126 , the SGW  124  delivers (at  218 ) the IP address and possibly the home network prefix to the mobile station  130  following E-UTRAN access procedures. 
     It is noted that from the perspective of the home agent  116 , the PDN gateway  126  appears to be a PDSN similar to PDSN  112  in the legacy service domain  102 . 
     Whenever the mobile station moves across the E-UTRAN wireless access network  120  that causes an inter-SGW transfer, the system ensures that the target SGW will receive the IP address of the current PDN gateway  126  that maintains a binding of the mobile station  130  to its current home agent. The target SGW will initiate the procedure discussed above, which causes the home agent  116  to assign the same IP address to the mobile station  130  to maintain IP mobility and connectivity using the same IP address. 
     If the mobile station  130  moves to the HRPD wireless access network  104  from the E-UTRAN wireless access network  120 , the system will provide the PDSN  112  with the address of the current home agent  116  that maintains and anchors the IP session of the mobile station  130 . When the PDSN  112  subsequently sends a proxy RRQ to the home agent  116 , the home agent  116  updates the mobile station binding with the new proxy care-of-address to point to the PDSN  112  instead of the PDN gateway  126 . 
     In accordance with at least one other embodiment, as illustrated in  FIG. 3 , a GRE (Generic Routing Encapsulation) tunnel is employed over a link  302  between the PDN gateway  126  and the home agent  116 . GRE is a tunneling protocol that can encapsulate various network layer protocol packet types inside IP tunnels to create virtual point-to-point links. GRE is described in RFC 2784, entitled “Generic Routing Encapsulation (GRE),” dated March 2000, as updated by RFC 2890, entitled “Key and Sequence Number Extensions to GRE,” dated September 2000. 
     In some implementations, DHCP (Dynamic Host Configuration Protocol) functionality is supported by the PDN gateway  126  and home agent  116  to support the solution according to this embodiment. DHCP is a network application protocol used by devices (referred to as DHCP clients) to obtain configuration information regarding the DHCP client from a DHCP server. DHCP for IPv4 networks is described in RFC 2131, entitled “Dynamic Host Configuration Protocol,” dated March 1997. DHCP for IPv6 networks is described in RFC 3315, entitled “Dynamic Host Configuration Protocol for IPv6 (DHCPv6),” dated July 2003. 
     The PDN gateway  126  supports DHCP client functionality, while the home agent  116  supports DHCP relay functionality or DHCP server functionality. Since the DHCP client and server functionality between the PDN gateway  126  and the home agent  116  are not visible to the outside world, vendor-specific information can be communicated between the PDN gateway  126  and the home agent  116  using the DHCP protocol, such as GRE keys. 
     As with the embodiments associated with  FIGS. 1 and 2 , due to access authentication by the mobile station based on E-UTRAN access procedures, the SGW  124  receives user information, including the IP address of the PDN gateway  126 , along with other parameters such as user NAI, supported APNs, the user profile, and so forth. When the SGW  124  receives such information, including the IP address of the PDN gateway  126 , the SGW follows 3GPP procedures to establish an IP session for the mobile station at the PDN gateway  126 . For example, this can be accomplished by using a binding procedure ( 310 ) that includes sending a proxy binding update message (according to Proxy Mobile IPv6) to the PDN gateway  126  to request an IP address (and possibly an IPv6 home network prefix). 
     Upon receiving the proxy binding update message from the SGW  124 , the PDN gateway  126  using out-of-band signaling or static configuration is able to find the IP address of the home agent  116  that is supposed to anchor the IP session of the mobile station. The PDN gateway  126  identifies the static GRE tunnel over the link  302  that is used to communicate with the home agent  116 . If no GRE tunnel exists, the PDN gateway  126  will initiate establishment of the GRE tunnel. 
     Next, the PDN gateway  126  sends (at  312 ) a DHCP request to the home agent  116  on the GRE tunnel. The DHCP request includes the user identity and an IP address allocation request. Optionally, the DHCP request may also include a request for a GRE key in case IP private address overlapping is supported. 
     When the home agent  116  receives the DHCP request, the home agent either allocates (at  314 ) the IP address locally (as part of DHCP server functionality) or uses DHCP relay functionality to obtain the information from another DHCP server to allocate the IP address for the mobile station. 
     When the IP address of the mobile station is allocated, the home agent  116  maintains a binding of the user NAI and the mobile station&#39;s home IP address, and the GRE tunnel interface (the PDN gateway  126  that sent the DHCP request) that this session/IP address belongs to. 
     The home agent  116  then sends (at  316 ) a DHCP response that is responsive to the DHCP request sent at  312 . When the PDN gateway  126  receives the DHCP response, the PDN gateway  126  updates the mobile station&#39;s BCE with the newly allocated IP address, and the home agent IP address is updated with the current GRE tunnel interface. 
     In response to the proxy binding update message from the SGW  124 , the PDN gateway  126  sends a proxy binding acknowledgment message (part of the binding procedure  310 ) to the SGW  124  with the assigned home IP address and other parameters (including possibly the IPv6 home network prefix). Upon receiving the proxy binding acknowledgment message from the PDN gateway  126 , the SGW  124  delivers (at  318 ) the allocated IP address (and possibly the home network prefix) to the mobile station, using E-UTRAN access procedures. 
     In case the mobile station moves across cells in the E-UTRAN wireless access network  120  such that an inter-SGW transfer occurs, the target SGW will receive the current mobile station&#39;s PDN gateway IP address to maintain a binding of the mobile station with its home agent. The home agent will assign the same IP address to the same mobile station to maintain IP mobility and connectivity using the same IP address. 
     If the mobile station moves to the HRPD access network  104 , the system will provide the PDSN  112  with the current home agent that maintains and anchors the mobile station&#39;s IP session. When the PDSN  112  sends a proxy RRQ message to the home agent  116 , the home agent  116  validates the list of mobile station bindings including those established over the GRE tunnel with the PDN gateway  126  using the DHCP protocol. If the same user NAI is already assigned to the IP address, the home agent  116  updates the mobile station binding with the new proxy care-of-address to point to the PDSN  112  instead of the PDN gateway  126 . 
       FIG. 4  is a block diagram of nodes that are part of the networks depicted in  FIGS. 1-3 . A first service domain node  400  can be a node in the LTE service domain  100 , and the home agent node  402  is a node that contains the home agent  116  of  FIGS. 1-3 . A “node” refers to any computing/processing assembly. For example, the first service domain node  400  can be either the SGW  124  or PDN gateway  126  of  FIGS. 1-3 . 
     In the example of  FIG. 4 , the first service domain node  400  includes software  404  executable on a processor  406 . The software  404  includes various software modules that perform tasks of the SGW  124  and/or PDN gateway  126  discussed above. The processor is connected to a storage media  410 , and an interface  408  that allows the first service domain node  400  to communicate with the home agent node  402 . 
     The home agent node  402  includes software  414  executable on a processor  416  to perform various tasks of the home agent  116  discussed above. The processor  416  is connected to a storage media  420  and an interface  418  to allow the home agent node  402  to communicate with the first service domain node  400 . 
     Instructions of the software  404  and  414  can be loaded from respective storage media  410  and  420  for execution on the processors  406  and  416 , respectively. A processor includes microprocessors, microcontrollers, processor modules or subsystems (including one or more microprocessors or microcontrollers), or other control or computing devices. A “processor” can refer to a single component or to plural components (e.g., one CPU or multiple CPUs). 
     Data and instructions (of the software) are stored in respective storage devices, which are implemented as one or more computer-readable or computer-usable storage media. The storage media include different forms of memory including semiconductor memory devices such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; magnetic disks such as fixed, floppy and removable disks; other magnetic media including tape; and optical media such as compact disks (CDs) or digital video disks (DVDs). 
     In the foregoing description, numerous details are set forth to provide an understanding of one or more embodiments. However, it will be understood that alternate embodiments may be practiced without these details. While various embodiments have been discussed, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover such modifications and variations.