HK1099458A - Methods and apparatuses for cdma2000/gprs roaming - Google Patents

Description

Method and apparatus for CDMA 2000/GPRS roaming

According to the priority required of 35 U.S.C. § 119

This application claims priority to a provisional application number 60/526,557 entitled "CDMA/GPRS Packet Data Roaming," filed on 3.12.2003, assigned to the present assignee and incorporated herein by reference.

Technical Field

The presently disclosed embodiments relate generally to wireless communications and, more particularly, to roaming in the CDMA2000 and GPRS systems.

Background

Wireless subscribers may wish to use their wireless terminals in conjunction with a wireless system other than their home system to gain access to services using their existing subscriptions. Access to these services may be independent of their normal wireless terminals by means of wireless systems other than their home system. This may occur, for example, when a subscriber roams outside the service area of their home system. Accordingly, if the terminal and service systems are compatible, manufacturers and system operators wish to enable subscribers to use their terminals and subscriptions to receive services via systems other than the subscriber's home system.

Even when the serving system and the home system use exactly the same technology, it may be difficult to serve the roaming user. When the serving system uses a different air interface than the one used in the subscriber's home system, interworking between these systems needs to be performed due to fundamental differences in message protocols, call modes, etc. This Interworking may be achieved via an Interworking and Interoperability Function IIF.

An example of IIF is described in U.S. patent application 2002/094811A1 "Interworking and Interoperability of GPRS Systems With Systems of Other technology facilities" to Bright et al. Us patent application 2002/094811a1 provides a GPRS Interworking and Interoperability Function (IIF) interposed between a GSM/GPRS radio system and a second radio system of a different technology family of services. The IIF enables mobile stations belonging to the second radio system to operate in the GSM/GPRS system. In accordance with U.S. patent application 2002/094811A1, there is provided a telecommunications system component that enables interworking and interoperation of a serving GSM and/or GPRS system with certain "national wireless" systems. For example, a mobile station located in such a domestic wireless system, but registered with the serving system only in GPRS mode, may receive service from the serving system. Us patent application 2002/094811a1 mentions: the term "Domestic Wireless (DW) is intended to refer to non-GSM systems that are compatible with ANSI or equivalent standards for TDMA, CDMA, and analog cellular systems (typically used in north america), or with other similar systems.

Although US patent application 2002/094811a1 confirms that an IIF is required to enable a mobile station located in a CDMA wireless system to operate in a GSM/GPRS system, US patent application 2002/094811a1 does not discuss an IIF suitable for a CDMA 2000/GPRS roaming scheme when a terminal uses mobile IP or simple IP. Us patent application 2002/094811a1 fails to provide sufficient information, instructions or guidance to inform how an IIF can be constructed that enables a mobile station belonging to a CDMA2000 wireless system to operate in a GSM/GPRS system when the terminal uses mobile IP or simple IP. For example, U.S. patent application 2002/094811a1 fails to provide any details as to what modules may be needed to implement such an IIF, how the modules are interconnected, timed, and controlled in order to obtain the specific operations needed to implement such an IIF.

Thus, there is a need in the art for a general architecture that may be adapted for CDMA 2000/GPRS roaming schemes such as GPRS foreign mode (foreign mode) with mobile IPv4, GPRS foreign mode with simple IPv4 or IPv6, CDMA2000 packet data foreign mode with mobile IPv4, and CDMA2000 packet data foreign mode with simple IP, mobile IPv4 or mobile IPv 6. It may be desirable to be able to communicate between a CDMA2000 packet data system and a GPRS system when a CDMA2000 packet data native subscriber using simple IP, mobile IPv4 or mobile IPv6 roams to the GPRS system by supporting bearer connectivity between the GPRS and CDMA2000 packet data systems. Similarly, it may also be desirable to enable communication between a GPRS system and a CDMA2000 packet data system when a GPRS native subscriber roams from the GPRS system to the CDMA2000 packet data system using simple IP, mobile IPv4 or mobile IPv6 by supporting bearer connectivity between the GPRS system and the CDMA2000 packet data system.

Disclosure of Invention

In accordance with one aspect of the present invention, there is provided an interface entity interposed between a CDMA2000 packet data system and a GPRS system for enabling communication between said CDMA2000 packet data system and the GPRS system by providing a packet routing function to support bearer connectivity between the GPRS and CDMA2000 packet data systems when a CDMA2000 packet data native subscriber roams to the GPRS system.

In accordance with one aspect of the present invention, there is provided an interface entity for enabling communication between a home CDMA2000 packet data system and a visited GPRS system comprising a Serving GPRS Support Node (SGSN) when a CDMA2000 packet data native subscriber using mobile IPv4 roams to the visited GPRS system.

For example, in an embodiment in which a CDMA2000 packet data native subscriber roams to a visited system and uses mobile IPv4, an interface entity may be provided for connecting the home system to the visited system to enable communication between the home system and the visited system. In this case, the home system is a CDMA2000 packet data system and may include an ANSI-41 home location register; an AAA entity; and a home agent, and the visited system may be a GPRS system including an SGSN.

In one aspect of this embodiment, the interface includes a GSM Home location register emulation module and an ANSI-41 visitor location register emulation module. The GSM home location register emulation module may be connected to the SGSN via a Gr interface, the GSM home location register emulation module enabling subscribers to register via the Gr interface, and the ANSI-41 visitor location register emulation module may be connected to the ANSI-41 home location register via a D interface, the ANSI-41 visitor location register emulation module enabling subscribers to register via the D interface. In accordance with one aspect of this embodiment, the interface further includes a foreign agent emulation module and a GGSN emulation module. The foreign agent emulation module may connect to the home agent via an X1 interface and support bearer connectivity between the visited and home systems such that the CDMA2000 packet data system is presented with a foreign agent interface and an AAA interface via an X1 interface. The GGSN emulation module can be connected to the SGSN via a Gp interface and can support bearer connectivity between the visited system and the home system such that the visited system is given a GGSN interface via the Gp interface. The interface may act as an endpoint for GTP tunnels and mobile IP tunnels. In this embodiment, the interface provides packet routing functionality between the GGSN interface and the foreign agent interface. In accordance with another aspect of this embodiment, the interface may further include an AAA emulation module that may be connected to the AAA entity via the X3 interface. In this embodiment, the AAA emulation module provides the accounting function by interacting with the AAA of the home network for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

In accordance with one aspect of the present invention, there is provided an interface entity for enabling communication between a home CDMA2000 packet data system and a visited GPRS system comprising a Serving GPRS Support Node (SGSN) when a CDMA2000 packet data native subscriber using simple IP roams to the visited GPRS system.

In embodiments where a CDMA2000 packet data local subscriber roams to a visited system and uses simple IP, an interface entity may be provided for connecting the home system to the visited system to enable communication between the home system and the visited system. In this case, the home system is a CDMA2000 packet data system and may include an ANSI-41 home location register; an AAA entity; and an LNS, and the access system may be a GPRS system including an SGSN.

In one aspect of this embodiment, the interface includes an ANSI-41 visitor location register and a GSM Home location register. The ANSI-41 visitor location register may be connected to the ANSI-41 home location register via a D interface and enable subscribers to register via the D interface. The GSM home location register may be connected to the SGSN via a Gr interface and enables subscribers to register via the Gr interface. In accordance with another aspect of this embodiment, the interface may include a LAC emulation module and a GGSN emulation module. The LAC emulation module can be connected to the LNS via an X2 interface and support bearer connectivity between the visited network and the home network via the X2 interface. The GGSN emulation module may be connected to the SGSN via a Gp interface and support bearer connections between the visited and home networks via the Gp interface by giving the visited system a GGSN interface and giving the CDMA2000 packet data system a normal routing interface, thereby providing a packet routing function between the GGSN interface and the home system. In this case, the interface acts as an endpoint for the GTP tunnel and the IPSec tunnel. In accordance with yet another aspect of this embodiment, the interface may further include an AAA emulation module, which may be connected to the AAA entity via the X3 interface. The AAA emulation module may provide the charging function by interacting with the AAA of the home network for L2TP authentication and 3GPP2 packet data charging via the X3 interface.

In accordance with another aspect of the present invention, there is provided an interface entity interposed between a GPRS system and a CDMA2000 packet data system for enabling communication between the GPRS system and the CDMA2000 packet data system by providing a packet routing function to support a bearer connection between the GPRS system and the CDMA2000 packet data system when a GPRS native subscriber using one of mobile IPv4 and simple IP roams from the GPRS system to the CDMA2000 packet data system.

In accordance with yet another aspect of the present invention there is provided an interface entity for enabling communication between a home GPRS system and a visited CDMA2000 packet data system when a GPRS native subscriber using mobile IPv4 roams to the visited CDMA2000 packet data system, the home GPRS system comprising a GSM home location register, GGSN and AAA entity, and the visited CDMA2000 packet data system comprising an ANSI-41 visitor location register, an AAA entity and a packet data service node/foreign agent.

In embodiments where a GPRS native subscriber roams to a visited system and uses mobile IPv4, an interface entity may be provided for connecting the home system to the visited system to enable communication between the home system and the visited system. In this case, the home system includes a GSM home location register; a GGSN; and a GPRS system of AAA entities, and the access system may be a GPRS system including ANSI-41 visitor location registers; a CDMA2000 packet data system with an AAA entity and a packet data serving node/foreign agent.

In accordance with one aspect of this embodiment, the interface further includes a home agent emulation module and an SGSN emulation module. The home agent emulation module may connect to the packet data serving node/foreign agent via the X1 interface and present the home agent interface to the visited system. The SGSN emulation module can be connected to the GGSN via a Gp interface and presents an SGSN interface to the home system to support bearer connectivity between the visited network and the home network by providing a packet routing function between the SGSN interface and the home agent interface. Here, the interface serves as an endpoint of a GTP tunnel and a mobile IP tunnel. In another aspect of this embodiment, the interface may further include an ANSI-41 Home location register emulation module and a GSM visitor location register emulation module. The ANSI-41 home location register emulation module can be connected to the ANSI-41 visitor location register via a D interface, and the GSM visitor location register emulation module can be connected to the GSM home location register via a D interface to enable subscriber registration. In accordance with yet another aspect of this embodiment, the interface may further comprise an AAA emulation module connectable to the AAA entity via a Gi interface and connected to the AAA entity via an X3 interface. The AAA emulation module interacts with the visited network AAA for mobile IP authentication and 3GPP2 packet data accounting via the X3 interface and with the AAA of the home network for 3GPP packet data accounting via the Gi interface.

In accordance with one aspect of the present invention there is provided an interface entity for enabling communication between a home GPRS system and a visited CDMA2000 packet data system when a GPRS native subscriber using simple IP roams to the visited CDMA2000 packet data system, the home GPRS system comprising a GSM home location register, a GGSN and an AAA entity, and the visited CDMA2000 packet data system comprising an ANSI-41 visitor location register, an AAA entity and a packet data serving node/LAC entity.

In an embodiment in which a GPRS local subscriber roams to a visited system and uses simple IP, an interface entity may be provided for connecting the home system to the visited system to enable communication between the home system and the visited system. In this case, the home system includes a GSM home location register; a GGSN; and a GPRS system of AAA entities, and the access system may be a GPRS system including ANSI-41 visitor location registers; a CDMA2000 packet data system with an AAA entity and a packet data serving node/LAC entity. In accordance with one aspect of the invention, the interface supports bearer connectivity between the visited network and the home network by providing packet routing functionality. For example, the interface may include an SGSN emulation module and an LNS emulation module. The SGSN emulation module can connect to the GGSN via the Gp interface and present the SGSN interface to the home system, while the LNS emulation module can connect to the packet data serving node/LAC entity via the X2 interface and present the L2TP Network Server (L2TP Network Server LNS) interface to the visited system. Thus, this interface provides packet routing functionality between the SGSN emulation module and the LNS emulation module. Here, the interface serves as an endpoint of a GTP tunnel and a mobile L2TP tunnel.

In accordance with another aspect of this embodiment, the interface includes an ANSI-41 Home location register emulation module and a GSM visitor location register emulation module. The ANSI-41 home location register emulation module can be connected to the ANSI-41 visitor location register via a D interface, while the GSM visitor location register emulation module can be connected to the GSM home location register via another D interface. This enables the subscriber to register. In accordance with yet another aspect of this embodiment, the interface may further include an AAA emulation module that may be connected to the AAA entity via a Y3 interface and to the AAA entity via an X3 interface. The AAA emulation module interacts with an AAA entity of a visited network for L2TP authentication and 3GPP2 packet data accounting via an X3 interface and interacts with an AAA entity of a home network for 3GPP packet data accounting via a Gi interface.

Drawings

FIG. 1 is a block diagram of a system including a home system, a visited system, and an interface entity that enables communication between the home system and the visited system;

figure 2A is a block diagram of the GPRS foreign mode with mobile IPv 4;

fig. 2B is a call flow diagram illustrating mobile IPv4 operation in GPRS foreign mode;

figure 3A is a block diagram of a GPRS foreign mode with simple IP;

fig. 3B is a call flow diagram illustrating simple IP operation in GPRS foreign mode;

fig. 4A is a block diagram of a CDMA2000 packet data foreign mode with mobile IPv 4;

fig. 4B is a call flow diagram illustrating operation of mobile IPv4 in CDMA2000 packet data foreign mode;

FIG. 5A is a block diagram of a CDMA2000 packet data foreign mode with simple IP; and

fig. 5B is a call flow diagram illustrating simple IP operation in CDMA2000 packet data foreign mode.

Detailed Description

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous embodiments.

As used herein, the term "agent advertisement" refers to the process by which a mobility agent becomes known to a mobile node.

As used herein, the term "agent discovery" refers to the process by which a mobile node may obtain the IP address of a home agent or a foreign agent depending on whether the mobile node is at or away from a home location. Proxy discovery occurs when a mobile node receives a proxy advertisement as a result of a periodic broadcast or in response to a request. The term "discovery" may be used interchangeably with the term "proxy discovery".

As used herein, the term "automatic home agent discovery" refers to the process by which a mobile node can obtain the IP address of the home agent on its home network, including broadcasting an address transmission registration request to a subnet of its home network.

As used herein, the term "care-of address" refers to the IP address of the mobile node's current point of attachment to the internet when the mobile node is not attached to the home network.

As used herein, the term "collocated care-of address" refers to a care-of address assigned to a network interface of a mobile node in place of the care-of address provided by the foreign agent.

As used herein, the term "correspondent node" refers to a node that sends or receives packets to a mobile node; the correspondent node may be another mobile node or a non-mobile internet node.

As used herein, the term "encapsulation" refers to the process of incorporating an original IP packet into another IP packet so that the fields in the original IP header temporarily lose their role.

As used herein, the term "foreign agent" refers to a mobility agent on a foreign network that can assist a mobile node in receiving datagrams delivered to a care-of address.

As used herein, the term "foreign network" refers to a network to which a mobile node attaches when it is not attached to its home network, and over which a care-of address is reachable from the rest of the internet.

As used herein, the term "home address" refers to an IP address assigned to a mobile node that is logically attached to its home network.

As used herein, the term "home agent" refers to a node on a home network that can effectively enable the mobile node to be reached at its home address even when the mobile node is not attached to its home network.

As used herein, the term "home network" refers to the network of the rest of the internet where the mobile node appears to be reachable by means of its assigned IP address.

As used herein, the term "mobile node" refers to a node that changes its point of attachment to the internet.

As used herein, the term "mobility agent" refers to a node, such as a router, that provides support services to a mobile node. The mobility agent may be a home agent or a foreign agent.

As used herein, the term "redirecting" refers to a message intended to change the routing characteristics of the node that received the message.

As used herein, the term "registration" refers to the process by which a mobile node notifies a home agent of its current care-of address.

As used herein, the term "remote redirection" refers to a redirection sent from a source that is not located on the local network. The source may be located anywhere on the global internet and may be malicious and difficult to track.

As used herein, the term "route optimization" refers to a process that enables packets to be delivered directly from a correspondent node to a care-of address without having to detour through the home network.

As used herein, the term "tunnel" has a meaning similar to the term "encapsulation", but with additional meaning with respect to changing the internet routing effect on the original IP packets.

For short

For each of the following terms, the following description uses the following abbreviations:

access, Authorization and Accounting (Access, Authorization and Accounting AAA)

Challenge Handshake Authentication protocol (Challenge Handshake Authentication protocol CHAP)

Domain Name System or Server (Domain Name System or Server DNS)

Foreign Agent (Foreign Agent FA)

Foreign Agent Challenge (Foreign Agent Challenge FAC)

General Packet Radio System (General Packet Radio System GPRS)

Gateway GPRS Support Node (Gateway GPRS Support Node GGSN)

Global System for Mobile communications GSM

GPRS Tunneling Protocol (GPRS Tunneling Protocol GTP)

Home Agent (Home Agent HA)

Home authentication, authorization and accounting (HAAA)

Home Location Register (HLR)

Internet Protocol Control Protocol (Internet Protocol Control Protocol IPCP)

Link Access Control (Link Access Control LAC)

Link Control Protocol (Link Control Protocol LCP)

L2TP network server (LNS)

Mobile Station (Mobile Station MS)

Mobile Switching Center (Mobile Switching Center MSC)

Mobile Station ID (Mobile Station ID MSID)

Network Access Identifier (Network Access Identifier NAI)

Network Access Server (Network Access Server NAS)

PPP Authentication Protocol (PPP Authentication Protocol PAP)

Packet Control Function (Packet Control Function PCF)

Packet Data Serving Node (Packet Data Serving Node PDSN)

Point-to-Point Protocol (Point to Point Protocol PPP)

Radio Access Network (Radio Access Network RAN)

Serving GPRS Support Node (SGSN)

Access authentication, authorization and accounting (VAAA)

Visitor Location Register (VLR)

Fig. 1 is a system comprising a home system 10 (such as a CDMA2000 packet data system or GPRS system), a visited system 20 (such as a GPRS system or CDMA2000 packet data system) and an interface entity 30 or "IIF" that connects the home system 10 to the visited system 20 and enables communication between the home system 10 and the visited system 20.

The following sections describe architectures that may be suitable for CDMA 2000/GPRS roaming schemes such as GPRS foreign mode with mobile IPv4, GPRS foreign mode with simple IPv4 or IPv6, CDMA2000 packet data foreign mode with mobile IPv4, and CDMA2000 packet data foreign mode with simple IPv4 or IPv 6.

GPRS foreign mode with mobile IPv4

Figure 2A is an exemplary block diagram of the GPRS foreign mode with mobile IPv4 and depicts the functionality and control interfaces provided by the IIF in this embodiment. This roaming scheme occurs when a CDMA2000 packet data home subscriber operates mobile IPv4 IS-835-C in the GPRS foreign mode. In this embodiment, the home system 10 may be a CDMA2000 packet data system, where a CDMA2000 packet data native subscriber roams to a GPRS system and uses mobile IPv 4. The home system 10 includes an ANSI-41 home location register 131, an AAA entity 116, and a home agent 135. Visiting system 20 may be a GPRS system that includes a Serving GPRS Support Node (SGSN) 137. The serving GPRS support node keeps track of the location of individual mobile stations and performs security functions and access control. The AAA entity may be used to reliably determine the identity and privileges of a user and track the activities of that user.

Interface 30 or "IIF" includes ANSI-41 visitor location register 111 connected to ANSI-41 home location register 131 via D interface 113, GSM home location register 124 connected to Serving GPRS Support Node (SGSN)137 via Gr interface 123, Gateway GPRS Support Node (GGSN)126 connected to Serving GPRS Support Node (SGSN)137 via Gp interface 127 and to the internet via a Gi interface, AAA entity 140 connected to AAA entity 116 via X3 interface 117, and foreign agent 118 connected to home agent 135 via X1 interface 115. The Gr interface is a GPRS interface located between SGSN (serving GPRS support node) and HLR (home location register). When the GGSN (gateway GPRS support node) and SGSN (serving GPRS support node) are located in different networks, they may be interconnected via a Gp interface, which provides similar functionality as the Gn interface, however it typically includes additional security functions based on mutual agreement between operators. The Gi interface is a GPRS interface between GGSN (gateway GPRS support node) and external PDN (public data network). The gateway GPRS support node supports the edge routing function of the GPRS network. The GGSN performs the tasks of an IP router to the external packet data network. Firewall and filtering functions for protecting the integrity of the GPRS core network are also associated with the GGSN, along with billing functions.

The IIF provides GSM HLR and ANSI-41VLR emulation to enable subscriber registration. This interworking may be provided via the interface labels "Gr" and "D". A Home Location Register (HLR) is a database found within a cellular network. In addition to the location area based information it stores user data related to services and features. In the context of GSM, a Home location register is a database within the HPLMN (Home Public Land Mobile Network). It provides routing information to MT (mobile terminated) calls and SMS (short messaging service). It is also responsible for maintaining subscriber subscription information. This is distributed to the concerned VLR (visitor location register) or SGSN (serving GPRS support node) by additional procedures and mobility management procedures such as location area and routing area updates. A Visitor Location Register (VLR) contains all subscriber data required for call handling and mobility management for mobile users currently located in the area controlled by the VLR.

The IIF also provides Gateway GPRS Support Node (GGSN) and FA emulation to support bearer connectivity between the visited and home networks via the IIF. This interworking may be provided via the interfaces labeled "Gn" and "X1". The IIF provides AAA emulation to interact with the home network's AAA for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting. This interworking may be provided via an interface labeled "X3".

If no bearer connection is required between the GPRS system and the CDMA2000 packet data system, no reverse tunneling over the X1 interface is required. Instead, the MS terminates traffic across the X1 and Gp interfaces. If reverse tunneling is not required, the IIF routes MS-originated traffic received on the Gp interface directly to the internet via the Gi interface.

Thus, for a user located in a CDMA mobile IP system roaming to a GSM system, the IIF may present a Gateway GPRS Support Node (GGSN) interface to GSM and FA and AAA interfaces to the CDMA system. The IIF may utilize packet routing functions between the Gateway GPRS Support Node (GGSN) and the FA as endpoints for GTP and mobile IP tunnels. The GPRS tunneling protocol is used on the Gn interface to tunnel user data between different GGSNs. The Gn interface is a GPRS interface located between GSNs (GPRS support nodes). The zero version protocol supports signaling and user data under a common header. It may be used with UDP User Datagram Protocol (UDP) or Transmission Control Protocol (TCP).

The IIF may also provide a billing function so that operators may charge based on configurable metrics such as packet count, bandwidth, time, etc.

Fig. 2B is an exemplary call flow diagram illustrating operation of mobile IPv4 in GPRS foreign mode. Fig. 2B depicts an example of call flow for a roaming scenario in which a CDMA2000 packet data home subscriber operates mobile IPv4 IS-835-C in GPRS foreign mode. In this example, the MS shares a secret key with the home CDMA2000 system for mobile IP authentication. The MS may request that the home CDMA2000 system assign a HA and/or IP address. Reverse tunneling may be allowed so that all data traffic (MS origination and termination) passes through the IIF and the home CDMA2000 system. The IIF generates a 3GPP2 packet data accounting record and sends it to the home CDMA2000 system via RADIUS.

The MS performs GPRS attach (attach) with the SGSN. The authentication associated with GPRS attach may be a SIM-based authentication requiring a Ki secret key. The IIF acts as a GSM HLR configured with Ki secret key. In any case, the IIF may not be required to communicate with the HLR in the home CDMA2000 system for authentication. (step 1). The MS sends an Activate PDP Context Request (Activate PDP Context Request) to the SGSN. The message includes an Access Point Name (APN). The APN has the format < network ID > < MNC > < MCC >. gprs. Network ID (e.g., cdma2000carrier. com) indicates with which external network the MS wants to establish a logical connection. The requested PDP address may be omitted in the message. The MS has a static mobile IP home address or obtains a new mobile IP home address. (step 2). A Serving GPRS Support Node (SGSN) selects a Gateway GPRS Support Node (GGSN) based on the APN. The Serving GPRS Support Node (SGSN) uses the APN as a lookup name to query a DNS server (not shown in the figure) and to obtain a list of available GGSNs, which may be used to support the requested APN. The domain name server maintains a database for resolving host names and IP addresses. The network device queries the DNS server by specifying the remote computer host name and receives the host IP address in return.

The network ID of the APN indicates the CDMA2000 operator; thus the DNS server returns with the IP address of the IIF. (step 3). The Serving GPRS Support Node (SGSN) sends an activate PDP context request to the selected IIF to establish a PDP context for the MS. The message includes the APN but the requested PDP address may be omitted. (step 4). The IIF acts as a Gateway GPRS Support Node (GGSN) and sends a Create PDP Context Response (Create PDP Context Response) to the Serving GPRS Support Node (SGSN), which then sends an Activate PDP Context accept (Activate PDP Context) to the MS. The PDP addresses in these two messages may be set to 0.0.0.0 to indicate that a PDP address will be allocated shortly after the mobile IP registration is successful. (step 5). The IIF acts as the FA and sends one or more mobile IP agent advertisements to the MS, since omitting the requested PDP address in the activate PDP context request may be an indication that the MS wants to use mobile IP. The agent advertisement may be sent on the established PDP context. The agent advertisement contains an FA care-of address and an FA challenge (FAC). (step 6).

The MS sends a mobile IP registration request to the IIF on the PDP context. The following information may be included in the registration request: the MS's NAI [ RFC 2794] has the format < username > @ < domain _ name >, where domain _ name identifies the MS's home CDMA2000 system. The MS-HA authenticator may be calculated from the contents of the registration request and the secret key shared between the MS and the HA RFC 2002. The MS-AAA authenticator may be calculated from the FAC and the secret key shared between the MS and the home AAA server RFC 3012. The HA address field may be set to a known value if the MS uses a permanent HA, or to 0.0.0.0 if the MS wants a new HA assigned by the home network. The home address field may be set to a known value if the MS uses a permanent address, or to 0.0.0.0 if the MS wants a new address assigned by the HA. The T bit may be set to 1 to allow reverse tunneling from the IIF to the HA of the MS. (step 7). The IIF acts as a RADIUS client and sends a RADIUS access request to the home AAA server. The RADIUS access request conveys the MS's NAI, FAC authentication code, FAC, HA address, etc. [ IS-835 ]. (step 8). If the authentication is successful, the home AAA server responds with a RADIUS Access-Accept (RADIUS Access-Accept) that includes the MS's HA address. (step 9). The IIF acts as an FA and forwards the mobile IP registration request to the HA address contained in the RADIUS access accept. (step 10). The HA checks the MS-HA authentication code in the mobile IP registration request. If the HA does not have a shared secret key, as with a dynamically assigned HA, then it will communicate with the home AAA server for the shared secret key. The HA responds to the Mobile IP Registration request with a Mobile IP Registration Reply (e.g., success or error code) containing the Registration result. If the MS wishes to obtain a new home address, the new address may be returned in the registration reply; otherwise, the permanent address of the MS may be returned. (step 11). The IIF acts as the FA and forwards the mobile IP registration reply to the MS over the appropriate PDP context. The IIF FA function notes the assigned MS IP address and shares it with the IIF Gateway GPRS Support Node (GGSN) function. (step 12)

The IIF acts as a Gateway GPRS Support Node (GGSN) and updates its PDP context by setting the PDP address to the home address of the MS (as indicated in the registration reply and shared by the FA function). The PDP address (and hence the MS's home address) may be associated with a GTP tunnel identified by the tunnel endpoint id (teid). (step 13). The IIF acts as a Gateway GPRS Support Node (GGSN) and triggers a PDP context modification procedure that initiates the GGSN to update the PDP addresses in the Serving GPRS Support Node (SGSN) and the MS 3GPP TS 29.061. The IIF sends an Update PDP Context Request (Update PDP Context Request) to the Serving GPRS Support Node (SGSN), which forwards it to the MS. (step 14). The MS responds with an Update PDP Context Response (Update PDP Context Response) to the Serving GPRS Support Node (SGSN), which forwards it to the IIF. (step 15). The IIF acts as a RADIUS client and sends a RADIUS accounting request (start) to the home AAA server [ IS-835 ]. The 3GPP2 vendor specific attributes are used to convey charging records, but some airlink record attributes (e.g., service option, mux option, etc.) do not apply. (step 16). The home AAA server responds with a RADIUS accounting response (start). (step 17). If reverse tunneling from the IIF to the HA is allowed, then bearer traffic passes through the IIF in both directions. To route MS-originated packets, the IIF routes packets received from the MS's GTP tunnel (identified by the TEID) to the MS's HA via the mobile IP reverse tunnel. To route MS-terminated packets, the IIF routes packets received from the HA-to-FA tunnel to the MS's GTP tunnel. IPSec can be used to protect mobile IP tunnels between HA and IIF and GTP tunnels between IIF and SGSN. (step 18)

GPRS foreign mode with simple IP

Fig. 3A is an exemplary block diagram of a GPRS foreign mode with simple IP, illustrating a roaming scenario in case a CDMA2000 packet data home subscriber operates IPv4 or IPv6 in the GPRS foreign mode. Fig. 3A also depicts the functional and control interfaces provided by the interface or IIF in this case. In this embodiment, the home system 10 may be a CDMA2000 packet data system, where a CDMA2000 packet data native subscriber roams to a GPRS system and uses simple IP. The home system 10 includes an ANSI-41 home location register 131, an AAA entity 116 and an LNS 139. Visiting system 20 may be a GPRS system that includes a Serving GPRS Support Node (SGSN) 137.

Interface 30 or "IIF" comprises an ANSI-41 visitor location register 111 connected to an ANSI-41 home location register 131 via a D interface 113, a GSM home location register 124 connected to a Serving GPRS Support Node (SGSN)137 via a Gr interface 123, a Gateway GPRS Support Node (GGSN)126 connected to the Serving GPRS Support Node (SGSN)137 via a Gp interface 127 and to the internet via a Gi interface, an AAA entity 140 connected to AAA entity 116 via an X3 interface 117, and an LAC entity 109 connected to LNS 139 via an X2 interface 119. The IIF provides GSM HLR and ANSI-41VLR emulation to enable subscriber registration. This interworking may be provided via interfaces labeled "Gr" and "D". The IIF also provides Gateway GPRS Support Node (GGSN) and LAC emulation to support bearer connectivity between the visited and home networks via the IIF. This interworking may be provided via interfaces labeled "Gn" and "X2". The link access control sublayer is a sublayer of the upper layer of layer 2 and provides a mechanism for correcting transmissions and delivering signaling messages that have been generated at layer 3.

The IIF also provides AAA emulation to interact with the home network's AAA for L2TP authentication and 3GPP2 packet data accounting. This interworking may be provided via an interface labeled "X3". L2TP uses the features of PPTP (point-to-point tunneling protocol) and L2F (layer 2 transport). It is capable of encapsulating PPP frames so they can be sent over IP, x.25, frame relay or ATM (asynchronous transfer mode) networks. When L2TP is used on an IP-based network, IP datagrams supporting L2TP payloads use the service of UDP (user datagram protocol).

The X2 interface is not required if a bearer connection between the CDMA2000 packet data system and the GPRS system is not required. The IIF still supports the Gp interface for the Serving GPRS Support Node (SGSN) and provides access to the internet via the Gi interface (not shown in the figure).

Thus, for a user roaming to a GSM system while in a CDMA simple IP system, the IIF may present a Gateway GPRS Support Node (GGSN) interface to GSM and a normal routing interface to the CDMA system. The IIF may utilize packet routing functions between the Gateway GPRS Support Node (GGSN) and the CDMA system as endpoints of GTP and IPSec tunnels. The IIF may also provide a billing function so that operators may charge based on configurable metrics such as packet count, bandwidth, time, etc.

Fig. 3B is a flow chart illustrating an exemplary call operating simple IP in GPRS foreign mode and explains the roaming scenario in the case where a CDMA2000 packet data home subscriber operates simple IP in GPRS foreign mode. In this example, the MS shares a secret key for simple IP authentication (i.e., CHAP) with the home CDMA2000 system. The MS establishes a PPP session to the home CDMA2000 system via L2 TP. During PPP establishment, the home CDMA2000 system dynamically assigns an IP address to the MS. All MS's data traffic (MS originated and MS terminated) traverses the IIF and the home CDMA2000 system. The IIF generates a 3GPP2 packet data accounting record and sends it to the home CDMA2000 system via RADIUS.

The MS performs GPRS attach (attach) with the SGSN. The authentication associated with GPRS attach may be a SIM-based authentication requiring a Ki secret key. The IIF acts as a GSM HLR or GSM VLR configured with Ki secret keys. In any case, the IIF may not be required to communicate with the HLR in the home CDMA2000 system for authentication. (step 1). The MS sends an activate PDP context request to the SGSN. The message includes an Access Point Name (APN). The APN has the format < network ID > < MNC > < MCC >. gprs. Com) indicates which external network the MS wants to establish a logical connection with. The requested PDP address may be omitted in the message so that the IIF (acting as GGSN) does not later assign an IP address to the MS; instead, the address is assigned by the LNS. (step 2). A Serving GPRS Support Node (SGSN) selects a Gateway GPRS Support Node (GGSN) based on the APN. The Serving GPRS Support Node (SGSN) queries a DNS server (not shown in the figure) and obtains a list of available GGSNs that can be used to support the requested APN. In this case, the network ID of the APN indicates the CDMA2000 operator; thus the DNS server returns with the IP address of the IIF. (step 3)

The Serving GPRS Support Node (SGSN) sends an activate PDP context request to the selected IIF to establish a PDP context for the MS. The message includes the APN but the requested PDP address may be omitted. (step 4). The IIF acts as a Gateway GPRS Support Node (GGSN) and sends a create PDP context response to the Serving GPRS Support Node (SGSN), which then sends an activate PDP context accept to the MS. The PDP address in these two messages may be set to 0.0.0.0 to indicate that the PDP address will be reset later. (step 5)

After the PDP context can be established, the MS and the IIF perform PPP LCP negotiation. The IIFLAC function establishes an L2TP tunnel with the LNS. The IIF determines which LNS is based on the requested APN. The IIF is configured with LNS information (e.g., IP address of LNS) corresponding to the APN. After establishing the L2TP tunnel, the IIF LAC function transfers LCP information between the LNS and the MS. During LCP negotiation, the LNS and MS negotiate PAP or CHAP in accordance with the protocol used for PPP authentication. (step 6). PPP authentication (PAP or CHAP) is performed. The MS's certificate is authenticated by the home AAA in the CDMA2000 system. The RADIUS interaction between LNS and home AAA is not shown in the figure. (step 7). The LNS and MS perform PPP IPCP negotiation. The IIF LAC function relays IPCP messages between the L2TP tunnel and the PDP context. During negotiation, the LNS assigns an IP address to the MS. The IIF monitors this address and uses it as the PDP address for the MS. (step 8)

The IIF also needs to inform the Serving GPRS Support Node (SGSN) and the MS of the updated PDP address. The PDP address may be initially set to 0.0.0.0. Thus, the IIF sends an update PDP context request to the Serving GPRS Support Node (SGSN), which forwards the PDP context request to the MS. (step 9). The MS responds with an update PDP context response to the Serving GPRS Support Node (SGSN), which forwards the update PDP context response to the IIF. (step 10)

The IIF acts as a RADIUS client and sends a RADIUS accounting request (start) to the home AAA server [ IS-835 ]. The 3GPP2 vendor specific attributes are used to convey billing records, but some air link record attributes (e.g., service option, multiplex option, etc.) do not apply. (step 11). The home AAA server responds with a RADIUS accounting response (start). (step 12). Bearer traffic traverses the IIF in both directions. To route MS-originated packets, the IIF routes packets received from the MS's GTP tunnel (identified by the TEID) to the MS's L2TP tunnel/session. To route MS terminated packets, the IIF routes packets received from the MS's L2TP tunnel/session to the MS's GTP tunnel. IPSec can be used to protect L2TP tunnels/sessions between LNS and IIF and GTP tunnels between IIF and SGSN. (step 13).

CDMA2000 packet data foreign mode with Mobile IPv4

Fig. 4A is an exemplary block diagram of a CDMA2000 packet data foreign mode with mobile IPv 4. This section describes a roaming scheme for GPRS native subscribers to operate mobile IPv4 IS-835-C in CDMA2000 packet data foreign mode. Figure 4A also depicts the functionality and control interfaces provided by the IIF in this case. In this embodiment, the home system 10 may be a GPRS system. A GPRS native subscriber roams to a CDMA2000 packet data system and uses simple IP. The home system 10 includes a GSM home location register 124, a Gateway GPRS Support Node (GGSN)126 and an AAA entity 128. The visited system 20 may be a CDMA2000 packet data system including ANSI-41 visitor location register 111, AAA entity 116, and packet data serving node/foreign agent 118.

Interface 30 or "IIF" includes ANSI-41 home location register 131 connected to ANSI-41 visitor location register 111 via D interface 113, GSM visitor location register 133 connected to GSM home location register 124 via D interface 121, Serving GPRS Support Node (SGSN)137 connected to Gateway GPRS Support Node (GGSN)126 via Gp interface 127, AAA entity 140 connected to AAA entity 128 via X4 interface 129 and to AAA entity 116 via X3 interface 117, and home agent 135 connected to packet data service node/foreign agent 118 via X1 interface 115. The IIF provides GSM VLR and ANSI-41HLR emulation to enable subscriber registration. This interworking may be provided via an interface labeled "D". The IIF also provides HA and Serving GPRS Support Node (SGSN) emulation to support bearer connectivity between the visited and home networks via the IIF. This interworking may be provided via the interfaces labeled "X1" and "Gn". The IIF also provides AAA emulation to interact with the AAA of the access network for mobile IP authentication and 3GPP2 packet data accounting. The IIF may also interact with the AAA of the home network for 3GPP packet data accounting. This interworking may be provided via the interface labels "X3" and "X4". The IIF/AAA requirements for the CDMA2000 packet data foreign mode with mobile IP will be described in greater detail below.

If a bearer connection between the visited CDMA2000 packet data system and the home GPRS system is not required, then the Gp interface is not required. In this case, mobile-originated data traffic may be routed directly to the Internet via a Packet Data Serving Node (PDSN)/FA in the visited system, or via an IIF/HA if reverse tunneling is allowed. Mobile terminated data traffic is routed to a Packet Data Serving Node (PDSN)/FA via the IIF/HA. Interfaces X3 and X4 are required for the IIF to interwork with AAA messages between the AAA server of CDMA2000 and the AAA server of GPRS.

Thus, for a user located in a GSM system roaming to a CDMA mobile IP system, the IIF may present an HA interface to the CDMA system and a Serving GPRS Support Node (SGSN) interface to the GSM system. A subset of Serving GPRS Support Node (SGSN) functions are required to include APN resolution. The IIF may utilize a packet routing function between the HA and the Serving GPRS Support Node (SGSN) function as an endpoint for mobile IP and GTP tunnels.

Fig. 4B is an exemplary call flow diagram illustrating mobile IPv4 operation in CDMA2000 packet data foreign mode. This call flow example illustrates a roaming scenario where a GPRS native subscriber operates mobile IPv4 IS-835-C in CDMA2000 packet data foreign mode. In this example, the home GPRS system does not support HA; thus, the MS and the IIF have a shared secret key for mobile IP authentication. The home GPRS system dynamically assigns an IP address to the MS. All MS data traffic (MS originated and MS terminated) goes through the IIF and home GPRS system. The IIF receives 3GPP2 accounting records from the visited CDMA2000 system and can map them to 3GPP accounting records and forward them to the home GPRS system via RADIUS.

The MS initiates SO 33 and establishes a PPP session with a Packet Data Serving Node (PDSN)/FA. (step 1). The Packet Data Serving Node (PDSN)/FA sends one or more mobile IP agent advertisements to the MS because the IP address configuration option is omitted during PPP IPCP negotiation indicating that the MS wants to use mobile IP. The agent advertisement contains an FA care-of address and an FA challenge (FAC). (step 2)

The MS sends a Mobile IP registration request to a Packet Data Serving Node (PDSN)/FA. The following information may be included in the registration request: the MS's NAI [ RFC 2794] has the format < usemame > @ < domain _ name >, where domain _ name identifies the MS's home GPRS system. The MS-HA authenticator may be calculated from the contents of the registration request and a secret key shared between the MS and the HA [ RFC2002 ]. The MS-AAA authenticator [ RFC 3012] may be calculated from the FAC and the secret key shared between the MS and the home AAA server. The HA address field may be set to a known value if the MS uses a permanent HA, or to 0.0.0.0 if the MS wants a new HA assigned by the home network. The HA field may be set to 0.0.0.0 to request a new address assigned by the HA. The T bit may be set to 1 to request a Packet Data Serving Node (PDSN)/FA to establish a reverse tunnel to the HA of the MS. (step 3)

A Packet Data Serving Node (PDSN)/FA generates a RADIUS access request for conveying the NAI, FAC authentication code, FAC, HA address, etc. of the MS [ IS-835 ]. Because the domain name of the NAI of the MS indicates the GPRS system, the Packet Data Serving Node (PDSN)/FA sends a RADIUS access request to the IIF via the AAA in the CDMA2000 system. The IIF may modify the message in accordance with [3GPP TS29.061 ]. (step 4). If the authentication is successful, the home AAA server responds with a RADIUS Access Accept. The message is routed back to the Packet Data Serving Node (PDSN) via the IIF and the visited AAA. The IIF may modify the message according to p.s0001-A V3.0.0. (step 5). The Packet Data Serving Node (PDSN)/FA forwards the mobile IP registration request to the HA function in the IIF. The IIF checks the MS-HA authentication code in the mobile IP registration request. (step 6)

If the authentication is successful, the IIF Serving GPRS Support Node (SGSN) function establishes a GTP tunnel with a Gateway GPRS Support Node (GGSN) in the home GPRS system and may request an IP address from the GGSN. The IIF Serving GPRS Support Node (SGSN) function derives an APN with the format < network ID >. MNC < MNC >. MCC >. GPRS [ TS 23.003 ]. < network ID > is the realm part of the NAI of the MS and indicates which Gateway GPRS Support Node (GGSN) the MS wants to access for the requested service. Deriving < MNC > and < MCC > from the IMSI of the MS. The NAI and IMSI of the MS may be obtained from the RADIUS access request in step 4. The Serving GPRS Support Node (SGSN) function uses the derived APN as a lookup name to query a DNS server for GPRS (not shown in the figure) and obtain therefrom a list of available GGSNs that can be used to support the requested service. The IIF Serving GPRS Support Node (SGSN) function sends a create PDP context request to the selected GGSN. The PDP address requested in the message is set to 0.0.0.0 to request a new IP address. (step 7). The Gateway GPRS Support Node (GGSN) responds with a create PDP context response that includes the new IP address assigned to the MS. (step 8). The IIF acts as an HA and sends a mobile IP registration reply to the MS via a Packet Data Serving Node (PDSN)/FA. The home address field in the mobile IP registration reply may be set to the IP address assigned by the GGSN. (step 9). The Packet Data Serving Node (PDSN) sends a RADIUS accounting request (start) containing 3GPP2 packet data accounting information p.s0001-AV 3.0. Because the realm name of the NAI of the MS indicates the GPRS system, RADIUS accounting requests are (initially) routed to the home AAA in the GPRS system via the visited AAA and IIF. The IIF may modify the message in accordance with [3GPP TS29.061 ]. (step 10). The IIF acts as a RADIUS server and responds with a RADIUS accounting response (start). (step 11)

Bearer traffic passes through the IIF in both directions. To route MS-originated packets, the IIF routes packets received from the mobile IP reverse tunnel to the MS's GTP tunnel (identified by the TEID). To route MS terminated packets, the IIF routes packets received from the GTP tunnel to the HA-to-FA tunnel. IPSec can be used to protect mobile IP tunnels between Packet Data Serving Node (PDSN)/FA and IIF and GTP tunnels between IIF and GGSN. (step 12)

IIF/AAA requirements for CDMA2000 packet data foreign mode with Mobile IP

The IIF requirements for handling RADIUS access requests received from an accessed CDMA2000 packet data system are now described.

The IIF proxies all IETF RADIUS attributes except for the Calling-Station-ID attribute (Call-Station-ID attribute), the Called-Station-ID attribute (Called-Station-ID attribute), and the frame-protocol attribute (Framed-protocol attribute), without modification. The processing of these three attributes will be described below. If the calling station ID attribute in the received RADIUS access request contains an IMSI, then the IIF copies the IMSI into the 3GPP-IMSI attribute [3GPP TS29.061] and includes it in the RADIUS access request to the MS's home GPRS system. The IIF does not include the calling station ID attribute in the RADIUS access request sent to the home AAA in the GPRS system. If the calling station ID attribute in the received RADIUS access request contains a MIN or IRM, then the IIF maps it to the IMSI for the MS used in the home GPRS system and includes it in the 3GPP-IMSI attribute of the RADIUS access request to the home GPRS system. The IIF does not include the calling station ID attribute in the RADIUS access request sent to the home AAA in the GPRS system.

The IIF includes the called station ID attribute in the RADIUS access request to the MS's home GPRS system. The value field of the called station ID attribute is set to APN (refer to part 8.3.4). If the frame protocol attribute is included in the received RADIUS access request, then the IIF reloads the value to 7[3GPP TS29.061 ]. The IIF removes all 3GPP2 VSAs from the received RADIUS access request. The IIF is not required to include any 3GPP VSA other than the 3GPP-IMSI attribute in the RADIUS access request sent towards the MS's home GPRS system.

The IIF requirements for handling a RADIUS access accept received from the MS's home GPRS system are now described.

The IIF proxies all ETF RADIUS attributes without modification. The IIF removes all 3GPP VSAs from the RADIUS access accept before sending the received RADIUS access accept to the visited CDMA2000 packet data system.

If the policy of the home GPRS system requires that the data traffic of the roaming MS pass through the home GPRS system via the IIF and include the HA address VSA in the corresponding RADIUS access request received earlier from the visited CDMA2000 packet data system, the IIF includes a Reverse-Tunnel-Specification VSA in the RADIUS access accept sent towards the visited CDMA2000 packet data system. The value field of the VSA is set to 1 to indicate that reverse tunneling is required.

The IIF requirements for handling the RADIUS accounting request START and the accounting request INTERIM are the same as the requirements for handling the RADIUS access request.

The IIF requirements for handling a RADIUS accounting request STOP are the same as the requirements for handling a RADIUS access request with the following additional requirements: if the Session-Continue VSA is set to FALSE in the received RADIUS accounting request STOP, and if the IIF has not previously received an accounting request (start) from another Packet Data Serving Node (PDSN) having the same IP address (in the case of inter-PDSN handover using mobile IP), the IIF inserts a 3GPP Session STOP Indicator (3GPP-Session-STOP-Indicator) VSA to indicate that the PDP Session has terminated.

CDMA2000 packet data foreign mode with simple IP

Fig. 5A is an exemplary block diagram of a CDMA2000 packet data foreign mode with simple IP. This section describes a roaming scheme for GPRS native subscribers to operate either IPv4 or IPv6 in CDMA2000 packet data foreign mode. Fig. 5A also depicts the functional and control interfaces provided by interface 30 or "IIF" in this case. In this embodiment, the home system 10 may be a GPRS system, where a GPRS native subscriber roams to a CDMA2000 packet data system and uses mobile IPv 4. The home system 10 includes a GSM home location register 124, a Gateway GPRS Support Node (GGSN)126 and an AAA entity 128. The visited system 20 may be a CDMA2000 packet data system including an ANSI-41 visitor location register 111, an AAA entity 116, and a home system 109.

The interface 30 or "IIF" comprises an ANSI-41 home location register 131 connected to the ANSI-41 visitor location register 111 via a D interface 113, a GSM visitor location register 133 connected to the GSM home location register 124 via a D interface 121, a Serving GPRS Support Node (SGSN)137 connected to the Gateway GPRS Support Node (GGSN)126 via a Gp interface 127, an AAA entity 140 connected to the AAA entity 128 via an X4 interface 129 and to the AAA entity 116 via an X3 interface 117, and an LCS entity 139 connected to the packet data service node/LAC entity 109 via an X2 interface 119. The IIF provides GSM VLR and ANSI-41HLR emulation to enable subscriber registration. This interworking may be provided via an interface labeled "D". The IIF also provides LNS and Serving GPRS Support Node (SGSN) emulation to support bearer connectivity between the visited and home networks via the IIF. This interworking may be provided via the interfaces labeled "X2" and "Gn". The IIF also provides AAA emulation to interact with the AAA of the visited network for L2TP authentication and 3GPP2 packet data accounting. The IIF may also interact with the AAA of the home network for 3GPP packet data accounting. This interworking may be provided via the interface labels "X3" and "X4". The IIF/AAA requirements for the CDMA2000 packet data foreign mode with simple IP will be described in greater detail below.

The X2 and Gp interfaces are not required if bearer connectivity between the visited CDMA2000 packet data system and the home GPRS system is not required. In this case, mobile originated and mobile terminated data traffic is routed to and from the internet via a Packet Data Serving Node (PDSN) in the visited system. Interfaces X3 and X4 are required for the IIF to inter-communicate AAA messages with the AAA server of CDMA2000 and the AAA server of GPRS.

Thus, for a user located in a GSM system roaming to a CDMA simple IP system, the IIF may present an L2TP network server (LNS) interface to the CDMA system and a Serving GPRS Support Node (SGSN) interface to the GSM system. A subset of Serving GPRS Support Node (SGSN) functions are required to include APN resolution. The IIF may utilize a packet routing function between the LNS and Serving GPRS Support Node (SGSN) functions as an endpoint for mobile L2TP and GTP tunnels.

Fig. 5B is an exemplary call flow diagram illustrating simple IP operation in a CDMA2000 packet data foreign mode. This call flow example illustrates a roaming scenario where a GPRS home subscriber operates simple IP in a CDMA2000 packet data foreign mode. In this example, the MS shares a secret key with the home AAA in the GPRS system for CHAP authentication. The home GPRS system dynamically assigns an IP address to the MS. All MS data traffic (MS originated and mobile terminated) goes through the IIF and home GPRS system. The IIF receives the 3GPP2 accounting record from the visited CDMA2000 system and can map it to the 3GPP accounting record and forward it to the home GPRS system via RADIUS.

The MS initiates the SO 33 and starts PPP LCP negotiation with the Packet Data Serving Node (PDSN)/LAC. CHAP may be negotiated as a protocol for PPP authentication. (step 1). The Packet Data Serving Node (PDSN)/LAC sends a CHAP challenge to the MS (step 2). The MS responds with its NAI and a challenge response calculated from the challenge and a secret key shared with the home AAA in the GPRS system. A Packet Data Serving Node (PDSN)/LAC sends a RADIUS access request. Because the realm name of the NAI of the MS indicates the GPRS system, the RADIUS access request can be routed to the home AAA in the GPRS system via the visited AAA and IIF, which proxies the message. The IIF may modify the message in accordance with [3GPP TS29.061 ]. (step 3). If the authentication is successful, the home AAA responds with a RADIUS Access Accept. The message is routed back to the Packet Data Serving Node (PDSN)/LAC via the IIF and the visited AAA. The IIF inserts a Tunnel-Server-Endpoint attribute into the RADIUS access accept. This attribute informs the Packet Data Serving Node (PDSN)/LAC to establish an L2TP tunnel with the IIF acting as an LNS. The Packet Data Serving Node (PDSN)/LAC sends a CHAP Success (CHAP Success) to inform the MS of the successful authentication. (step 4)

The Packet Data Serving Node (PDSN)/LAC establishes an L2TP tunnel/session with the IIF acting as an LNS. During the L2TP tunnel/session establishment, the Packet Data Serving Node (PDSN)/LAC forwards the LCP information (exchanged between the MS and the Packet Data Serving Node (PDSN)/LAC) to the IIF. The IIF LNS function may initiate a CHAP challenge (not shown in the figure) to authenticate the MS prior to IPCP negotiation. (step 5). The IIF Serving GPRS Support Node (SGSN) function establishes a GTP tunnel with a Gateway GPRS Support Node (GGSN) in the home GPRS system and may request an IP address from the GGSN. The IIF derives the APN with the format < network ID >. MNC < MNC >. MCC >. gprs. < network ID > is the realm part of the NAI of the MS and is used to indicate which Gateway GPRS Support Node (GGSN) the MS wants to access for the requested service. Deriving < MNC > and < MCC > from the IMSI of the MS. The NAI and IMSI of the MS may be obtained from the RADIUS access request in step 3. The IIF Serving GPRS Support Node (SGSN) function uses the derived APN as a lookup name to query a DNS server for GPRS (not shown in the figure) and obtain therefrom a list of available GGSNs that can be used to support the requested service. The IIF Serving GPRS Support Node (SGSN) function sends a create PDP context request to the selected GGSN. The PDP address requested in the message is set to 0.0.0.0 to request a new IP address. (step 6). The Gateway GPRS Support Node (GGSN) responds with a create PDP context response that includes the new IP address assigned to the MS. (step 7)

This new IP address may be assigned to the MS during PPP IPCP negotiation between the IIF and the MS. (step 8). The Packet Data Serving Node (PDSN)/FA sends a RADIUS accounting request (Start) containing 3GPP2 packet data accounting information [ IS-835 ]. The Packet Data Serving Node (PDSN) sends a RADIUS accounting request (start) containing 3GPP2 packet data accounting information p.s0001-A V3.0.0. Because the realm name of the NAI of the MS indicates the GPRS system, RADIUS accounting requests are (initially) routed to the home AAA in the GPRS system via the visited AAA and IIF. The IIF may modify the message in accordance with [3GPP TS29.061 ]. (step 9). The home AAA replies with a RADIUS accounting response (start) that is routed back to the Packet Data Serving Node (PDSN) via the IIF and the visited AAA. (step 10)

Bearer traffic passes through the IIF in both directions. To route MS-originated packets, the IIF routes packets received from the MS's L2TP tunnel/session to the MS's GTP tunnel (identified by the TEID). To route MS terminated packets, the IIF routes packets received from the MS's GTP tunnel to the MS's L2TP tunnel/session. IPSec can be used to protect L2TP tunnels/sessions between Packet Data Serving Nodes (PDSNs)/LACs and IIFs and GTP tunnels between IIFs and GGSNs. (step 11)

IIF/AAA requirements for CDMA2000 packet data foreign mode with simple IP

The IIF requirements for handling RADIUS access requests are the same as described above for handling RADIUS access requests for CDMA2000 packet data foreign mode with mobile IP.

The IIF requirements for handling RADIUS access acceptance are similar to those for handling RADIUS access acceptance for CDMA2000 packet data foreign mode with mobile IP, however if the policy of the home GPRS system requires that data traffic of the roaming MS pass through the home GPRS system via the IIF and the HA address VSA is not included in the corresponding RADIUS access request received earlier from the visited CDMA2000 packet data system, the IIF inserts Tunnel server endpoint, Tunnel Type (Tunnel-Type) and Tunnel Medium Type (Tunnel-Medium-Type) attributes in the sent RADIUS access acceptance towards the visited CDMA2000 packet data system. The tunnel server endpoint attribute indicates the IIF/LNS address. The tunnel type attribute indicates L2 TP. The tunnel media type attribute indicates IPv 4.

The IIF requirements for handling the RADIUS accounting request START and the accounting request INTERIM are the same as the above-described requirements for handling the RADIUS accounting request START and the accounting request INTERIM for the CDMA2000 packet data foreign mode.

The requirements for handling a RADIUS accounting request STOP are the same as the requirements for handling a RADIUS accounting request STOP for a CDMA2000 packet data foreign mode with mobile IP, however if the Session-Continue VSA is set to FALSE in the received RADIUS accounting request STOP and if the IP Technology (IP-Technology) VSA indicates simple IP, the IIF inserts a 3GPP Session STOP indicator VSA to indicate that the PDP Session has terminated.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, configurations, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, an optical disk, or any other form of storage medium known in the art. An exemplary storage medium may be coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

The previously described embodiments of the disclosure may be provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features defined by the disclosure herein.

Claims (71)

1. A method in which a user using mobile IP roams from a home system to a visited system comprising a Serving GPRS Support Node (SGSN), the method comprising:

connecting the home system to the visited system to enable communication between the home system and the visited system by means of the following steps, wherein the home system comprises a home agent, the steps comprising:

providing a foreign agent emulation module to the home system via a third interface; and

providing a Gateway GPRS Support Node (GGSN) emulation module to the access system via a fourth interface.

2. The method of claim 1, further comprising:

enabling the user to register via a first interface; and is

Enabling the user to register via a second interface.

3. The method of claim 1, wherein connecting the home system to the visited system to enable communication between the home system and the visited system comprises:

a bearer connection is supported between the home system and the visited system to enable communication between the home system and the visited system.

4. The method of claim 1, further comprising:

providing a packet routing function between the Gateway GPRS Support Node (GGSN) emulation module and the foreign agent emulation module.

5. The method of claim 4, further comprising:

endpoints for a GPRS Tunneling Protocol (GTP) tunnel and a mobile IP tunnel are provided.

6. The method of claim 1, wherein the home system further comprises a home location register, an access, authorization, and accounting (AAA) entity, and further comprising:

providing an access, authorization, and accounting (AAA) emulation module to the home system.

7. The method of claim 6, further comprising:

the accounting function is provided by interacting with the home system's access, authorization and accounting (AAA) for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

8. A method of enabling communication between a home system including a home agent and a visited system including a Serving GPRS Support Node (SGSN) when a user using mobile IP roams to the visited system, comprising:

connecting the home agent to a foreign agent emulation module via a third interface, wherein the foreign agent emulation module supports bearer connectivity between the visited system and the home system via the third interface; and is

Connecting a Gateway GPRS Support Node (GGSN) emulation module to the Serving GPRS Support Node (SGSN) via a fourth interface, wherein the Gateway GPRS Support Node (GGSN) emulation module supports bearer connectivity between the visited system and the home system via the fourth interface.

9. The method of claim 8, further comprising:

endpoints for a GPRS Tunneling Protocol (GTP) tunnel and a mobile IP tunnel are provided.

10. The method of claim 9, further comprising:

providing a packet routing function between the Gateway GPRS Support Node (GGSN) emulation module and a foreign agent emulation module.

11. The method of claim 8, wherein the home system further comprises a home location register, an access, authorization, and accounting (AAA) entity, and further comprising:

enabling the user to register via a first interface connecting a home location register emulation module of a global system for mobile communications to the SGSN; and is

Enabling the user to register via a second interface connecting a visitor location register emulation module to a home location register; and is

Connecting an access, authorization, and accounting (AAA) emulation module to an access, authorization, and accounting (AAA) entity via a fifth interface, wherein the access, authorization, and accounting (AAA) emulation module provides accounting functions by interacting with an access, authorization, and accounting (AAA) of a home system for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

12. A system in which a user using mobile IP roams into a visited system comprising a Serving GPRS Support Node (SGSN), the system comprising:

a home system including a home agent; and

an interface entity connecting the home system to the visited system to enable communication between the home system and the visited system, and wherein the interface entity further comprises:

a foreign agent emulation module connected to the home agent via a third interface for supporting bearer connectivity between the visited system and the home system such that the foreign agent emulation module is presented to the home system via the third interface; and

a Gateway GPRS Support Node (GGSN) emulation module connected to said Serving GPRS Support Node (SGSN) via a fourth interface for supporting bearer connectivity between said visited system and said home system, such that said Gateway GPRS Support Node (GGSN) emulation module is presented to said visited system via said fourth interface.

13. The system of claim 12, wherein the interface entity acts as an endpoint for a GPRS Tunneling Protocol (GTP) tunnel and a mobile IP tunnel.

14. A system according to claim 13, wherein said interface entity provides packet routing functionality between said Gateway GPRS Support Node (GGSN) emulation module and a foreign agent emulation module.

15. The system of claim 12, wherein the home system further comprises a home location register and an access, authorization, and accounting (AAA) entity, and wherein the interface entity further comprises:

a home location register emulation module of a global system for mobile communications connected to the Serving GPRS Support Node (SGSN) via a first interface, the home location register emulation module for enabling a subscriber to register via the first interface;

a visitor location register emulation module connected to the home location register via a second interface, the visitor location register emulation module for enabling a user to register via the second interface; and

an access, authorization, and accounting (AAA) emulation module connected to the access, authorization, and accounting (AAA) entity via a fifth interface, the access, authorization, and accounting (AAA) emulation module providing an accounting function by interacting with an access, authorization, and accounting (AAA) of a home system for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

16. An interface entity for enabling communication between a home system comprising a home agent and a visited system comprising a Serving GPRS Support Node (SGSN) when a user using mobile IP roams to a visited system, and wherein the interface entity comprises:

a foreign agent emulation module connected to the home agent via a third interface for supporting bearer connectivity between a visited interface entity and a home interface entity such that the foreign agent emulation module and a visited, authorized and accounting (AAA) emulation module are presented to the interface entity via the third interface; and

a Gateway GPRS Support Node (GGSN) emulation module connected to the Serving GPRS Support Node (SGSN) via a fourth interface, the Gateway GPRS Support Node (GGSN) emulation module being in the visited system and supporting bearer connectivity between the home system such that the visited system is presented with a Gateway GPRS Support Node (GGSN) emulation module via the fourth interface, wherein the interface entity provides packet routing functionality between the Gateway GPRS Support Node (GGSN) emulation module and the foreign agent emulation module and acts as an endpoint for a GPRS Tunneling Protocol (GTP) tunnel and a mobile IP tunnel.

17. The interface entity of claim 16, wherein the home system comprises a home location register and an access, authorization, and accounting (AAA) entity, and wherein the interface entity further comprises:

a home location register emulation module of a global system for mobile communications connected to the Serving GPRS Support Node (SGSN) via a first interface, the home location register emulation module enabling a user to register via the first interface;

a visitor location register emulation module connected to the home location register via a second interface, the visitor location register emulation module enabling a user to register via the second interface; and

an access, authorization, and accounting (AAA) emulation module connected to the access, authorization, and accounting (AAA) entity via a fifth interface, the access, authorization, and accounting (AAA) emulation module providing an accounting function by interacting with an access, authorization, and accounting (AAA) of a home system for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

18. A method in which a user using simple IP roams from a home system comprising an L2TP network server (LNS) to a visited system comprising a Serving GPRS Support Node (SGSN), the method comprising:

connecting the home system to the visited system to enable communication between the home system and the visited system by:

providing a Gateway GPRS Support Node (GGSN) emulation module to the visited system to support bearer connectivity between the visited network and a home network via a third interface; and

providing a Link Access Control (LAC) emulation module connected to an L2TP network server via a third interface, wherein the Link Access Control (LAC) emulation module supports bearer connectivity between the visited system and a home system via a fourth interface, thereby providing a normal routing interface to the home system.

19. A method according to claim 18, wherein a Gateway GPRS Support Node (GGSN) emulation module is provided to the visited system to support bearer connectivity between the visited and home networks via a third interface, a packet routing function being provided between the Gateway GPRS Support Node (GGSN) emulation module and the home system.

20. The method as recited in claim 18, further comprising:

enabling the user to register via a first interface; and is

Enabling the user to register via a second interface.

21. The method as recited in claim 18, further comprising:

endpoints for a GPRS Tunneling Protocol (GTP) tunnel and an IPSec tunnel are provided.

22. The method of claim 18, wherein the home system further comprises a home location register and an access, authorization, and accounting (AAA) entity, and further comprising:

the charging function is provided by interacting with access, authorization and accounting (AAA) of a home system for L2TP authentication and 3GPP2 packet data charging via a fifth interface.

23. A method for enabling communication between a home system including a L2TP network server (LNS) and a visited system including a Serving GPRS Support Node (SGSN) when a user using simple IP roams to the visited system, comprising:

connecting a Link Access Control (LAC) emulation module to an L2TP web server via a third interface, wherein the Link Access Control (LAC) emulation module supports bearer connectivity between the visited system and the home system via the third interface; and is

Connecting a Gateway GPRS Support Node (GGSN) emulation module to the Serving GPRS Support Node (SGSN) via a fourth interface to support bearer connectivity between the visited system and the home system via the fourth interface.

24. The method of claim 23, wherein connecting a Gateway GPRS Support Node (GGSN) emulation module to the Serving GPRS Support Node (SGSN) via a fourth interface to support bearer connectivity between the visited network and the home network via the fourth interface, comprises:

providing a Gateway GPRS Support Node (GGSN) emulation module to the access system.

25. The method of claim 23, further comprising:

providing a packet routing function between the Gateway GPRS Support Node (GGSN) emulation module and the home system.

26. The method of claim 23, wherein the home system further comprises a home location register, and the method further comprises:

connecting a visitor location register emulation module to the home location register via a first interface, wherein the visitor location register emulation module enables a subscriber to register via the first interface;

connecting a home location register emulation module of a global system for mobile communications to the Serving GPRS Support Node (SGSN) via a second interface, wherein the home location register emulation module of the global system for mobile communications enables a user to register via the second interface.

27. The method of claim 25, further comprising:

endpoints for a GPRS Tunneling Protocol (GTP) tunnel and an IPSec tunnel are provided.

28. The method of claim 23, wherein the home system further comprises an access, authorization, and accounting (AAA) entity, and the method further comprises:

connecting an access, authorization and accounting (AAA) emulation module to the access, authorization and accounting (AAA) entity via a fifth interface,

wherein the access, authorization and accounting (AAA) emulation module provides an accounting function by interacting with an access, authorization and accounting (AAA) entity of a home system for L2TP authentication and 3GPP2 packet data accounting via the fifth interface.

29. A system in which a user using simple IP roams into a visited system comprising a Serving GPRS Support Node (SGSN), the system comprising:

a home system comprising an L2TP network server (LNS); and

an interface entity connecting the home system to the visited system to enable communication between the home system and the visited system, wherein the interface entity further comprises:

a Link Access Control (LAC) emulation module connected to the L2TP network server via a third interface for supporting a bearer connection between the visited network and the home network via the third interface; and

a Gateway GPRS Support Node (GGSN) emulation module connected to the Serving GPRS Support Node (SGSN) via a fourth interface for supporting bearer connectivity between the visited and home networks via the fourth interface by providing the visited system with the Gateway GPRS Support Node (GGSN) emulation module and providing the system with a normal routing interface, thereby providing packet routing functionality between the Gateway GPRS Support Node (GGSN) emulation module and the home system.

30. The system of claim 29, wherein the interface serves as an endpoint for a GPRS Tunneling Protocol (GTP) tunnel and an IPSec tunnel.

31. The system of claim 29, wherein the home system further comprises a home location register, and wherein the interface entity further comprises:

a visitor location register emulation module connected to the home location register via a first interface for enabling a subscriber to register via the first interface; and

a home location register emulation module of a global system for mobile communications connected to the Serving GPRS Support Node (SGSN) via a second interface, the home location register emulation module for enabling a subscriber to register via the second interface.

32. The system of claim 29, wherein the home system further comprises an access, authorization, and accounting (AAA) entity, and wherein the interface further comprises:

an access, authorization, and accounting (AAA) emulation module connected to the access, authorization, and accounting (AAA) entity via a fifth interface, the access, authorization, and accounting (AAA) emulation module providing an accounting function by interacting with an access, authorization, and accounting (AAA) of a home system for L2TP authentication and 3GPP2 packet data accounting via the fifth interface.

33. An interface entity for enabling communication between a home system and a visited system comprising a Serving GPRS Support Node (SGSN) when a user using simple IP roams to the visited system, wherein the home system comprises an L2TP network server (LNS) and wherein the interface entity comprises:

a Link Access Control (LAC) emulation module connected to the L2TP network server via a third interface for supporting a bearer connection between the visited network and the home network via the third interface; and

a Gateway GPRS Support Node (GGSN) emulation module connected to the Serving GPRS Support Node (SGSN) via a fourth interface for supporting bearer connectivity between the visited network and the home network via the fourth interface by providing the visited system with a Gateway GPRS Support Node (GGSN) emulation module and providing the home system with a normal routing interface, thereby providing packet routing functionality between the Gateway GPRS Support Node (GGSN) emulation module and the home system.

34. An interface entity according to claim 33, wherein the interface entity acts as an endpoint for a GPRS Tunneling Protocol (GTP) tunnel and an IPSec tunnel.

35. An interface entity according to claim 33, wherein the home system further comprises a home location register, and wherein the interface entity further comprises:

a visitor location register emulation module connected to the home location register via a first interface for enabling a subscriber to register via the first interface;

a home location register emulation module of a global system for mobile communications connected to the Serving GPRS Support Node (SGSN) via a second interface, the home location register emulation module enabling a user to register via the second interface.

36. The interface entity of claim 33, wherein the home system further comprises an access, authorization, and accounting (AAA) entity, and wherein the interface entity further comprises:

an access, authorization, and accounting (AAA) emulation module connected to the access, authorization, and accounting (AAA) entity via a fifth interface, the access, authorization, and accounting (AAA) emulation module providing an accounting function by interacting with an access, authorization, and accounting (AAA) of a home system for L2TP authentication and 3GPP2 packet data accounting via the fifth interface.

37. A method in which a user using mobile IP roams from a home system to a visited system comprising a Serving GPRS Support Node (SGSN), the method comprising:

connecting the home system to the visited system to enable communication between the home system and the visited system, wherein the home system comprises a home location register, a visiting, authorization and accounting (AAA) entity, and a home agent.

38. The method of claim 37, further comprising:

enabling the user to register via a first interface; and is

Enabling the user to register via a second interface.

39. The method of claim 37, wherein connecting the home system to the visited system to enable communication between the home system and the visited system comprises:

a bearer connection is supported between the home system and the visited system to enable communication between the home system and the visited system.

40. The method of claim 37, wherein supporting a bearer connection between the home system and the visited system to enable communication between the home system and the visited system comprises:

presenting a foreign agent emulation module and an access, authorization, and accounting (AAA) emulation module to the home system via a third interface; and is

-presenting a Gateway GPRS Support Node (GGSN) emulation module to the access system via a fourth interface.

41. The method of claim 40, further comprising:

providing a packet routing function between the Gateway GPRS Support Node (GGSN) emulation module and a foreign agent emulation module.

42. The method of claim 41, further comprising:

endpoints for a GPRS Tunneling Protocol (GTP) tunnel and a mobile IP tunnel are provided.

43. The method of claim 37, further comprising:

the accounting function is provided by interacting with the access, authorization and accounting (AAA) of the home system for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

44. A method in which a user using simple IP roams from a home system to a visited system comprising a Serving GPRS Support Node (SGSN), the method comprising:

connecting the home system to the visited system to enable communication between the home system and the visited system; wherein the home system comprises a home location register, an access, authorization and accounting (AAA) entity and an L2TP network server (LNS).

45. The method of claim 44, wherein connecting the home system to the visited system to enable communication between the home system and the visited system comprises:

supporting a bearer connection between the visited network and the home network via a third interface by giving the visited system a Gateway GPRS Support Node (GGSN) emulation module, and

bearer connectivity is supported between the visited network and the home network via a fourth interface by presenting the home system with a normal routing interface.

46. The method of claim 44, further comprising:

providing a packet routing function between the Gateway GPRS Support Node (GGSN) emulation module and the home system.

47. The method of claim 44, further comprising:

enabling a user to register via a first interface; and is

Enabling the user to register via a second interface.

48. The method of claim 44, further comprising:

endpoints for a GPRS Tunneling Protocol (GTP) tunnel and an IPSec tunnel are provided.

49. The method of claim 48, further comprising:

the charging function is provided by interacting with access, authorization and accounting (AAA) of a home system for L2TP authentication and 3GPP2 packet data charging via a fifth interface.

50. A method of enabling communication between a home system and a visited system comprising a Serving GPRS Support Node (SGSN) when a user using mobile IP roams to the visited system, comprising:

wherein the home system comprises a home location register, an access, authorization, and accounting (AAA) entity, and a home agent;

connecting the home agent to a foreign agent emulation module via a third interface, wherein the foreign agent emulation module supports bearer connectivity between the visited system and the home system such that the foreign agent emulation module and an access, authorization, and accounting (AAA) emulation module are presented to the system via the third interface; and is

Connecting a Gateway GPRS Support Node (GGSN) emulation module to the Serving GPRS Support Node (SGSN) via a fourth interface, wherein the Gateway GPRS Support Node (GGSN) emulation module supports bearer connectivity between the visited system and the home system such that the visited system is given a Gateway GPRS Support Node (GGSN) emulation module via the fourth interface;

enabling the user to register via a first interface connecting a home location register emulation module of a global system for mobile communications to the SGSN; and is

Enabling the user to register via a second interface connecting a visitor location register emulation module to a home location register,

51. the method of claim 50, further comprising:

endpoints for a GPRS Tunneling Protocol (GTP) tunnel and a mobile IP tunnel are provided.

52. The method of claim 51, further comprising:

providing a packet routing function between the Gateway GPRS Support Node (GGSN) emulation module and the foreign agent emulation module.

53. The method of claim 50, further comprising:

connecting an access, authorization, and accounting (AAA) emulation module to the access, authorization, and accounting (AAA) entity via a fifth interface, wherein the access, authorization, and accounting (AAA) emulation module provides accounting functions by interacting with an access, authorization, and accounting (AAA) of a home system for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

54. A method for enabling communication between a home system and a visited system comprising a Serving GPRS Support Node (SGSN) when a user using simple IP roams to the visited system, wherein the home system comprises a home location register, a visiting, authorization and accounting (AAA) entity and an L2TP network server (LNS), the method comprising:

connecting a Gateway GPRS Support Node (GGSN) emulation module to the Serving GPRS Support Node (SGSN) via a fourth interface to support bearer connectivity between the visited network and the home network via the fourth interface.

55. A method according to claim 54, wherein connecting a Gateway GPRS Support Node (GGSN) emulation module to the Serving GPRS Support Node (SGSN) via a fourth interface to support bearer connectivity between the visited network and the home network via the fourth interface, comprises:

presenting a Gateway GPRS Support Node (GGSN) emulation module to the access system; and is

A normal routing interface is given to the home system.

56. The method of claim 54, further comprising:

providing a packet routing function between the Gateway GPRS Support Node (GGSN) emulation module and the home system.

57. The method of claim 54, further comprising:

connecting the visitor location register to the home location register via a first interface, wherein the visitor location register enables a user to register via the first interface;

connecting a home location register of a global system for mobile communications to the Serving GPRS Support Node (SGSN) via a second interface, wherein the home location register of the global system for mobile communications enables a subscriber to register via the second interface; and is

Connecting a Link Access Control (LAC) emulation module to an L2TP network server via a third interface, wherein the Link Access Control (LAC) emulation module supports bearer connectivity between the visited network and the home network via the third interface.

58. The method of claim 54, further comprising:

endpoints for a GPRS Tunneling Protocol (GTP) tunnel and an IPSec tunnel are provided.

59. The method of claim 58, further comprising:

connecting an access, authorization and accounting (AAA) emulation module to the access, authorization and accounting (AAA) entity via a fifth interface,

wherein the access, authorization and accounting (AAA) emulation module provides an accounting function by interacting with an access, authorization and accounting (AAA) of a home system for L2TP authentication and 3GPP2 packet data accounting via the fifth interface.

60. A system in which a user using mobile IP roams into a visited system comprising a Serving GPRS Support Node (SGSN), the system comprising:

a home system comprising a home location register, an access, authorization, and accounting (AAA) entity, and a home agent; and

an interface entity connecting the home system to the visited system to enable communication between the home system and the visited system, and wherein the interface entity further comprises:

a home location register emulation module of a global system for mobile communications connected to the Serving GPRS Support Node (SGSN) via a first interface, the home location register emulation module for enabling a subscriber to register via the first interface; and

a visitor location register emulation module connected to the home location register via a second interface for enabling a subscriber to register via the second interface;

a foreign agent emulation module connected to the home agent via a third interface for supporting bearer connectivity between the visited system and the home system such that the foreign agent emulation module and an access, authorization, and accounting (AAA) emulation module are presented to the system via the third interface; and

a Gateway GPRS Support Node (GGSN) emulation module connected to said Serving GPRS Support Node (SGSN) via a fourth interface for supporting bearer connectivity between said visited system and said home system, such that said visited system is given a Gateway GPRS Support Node (GGSN) emulation module via said fourth interface.

61. The system of claim 60, wherein the interface entity acts as an endpoint for a GPRS Tunneling Protocol (GTP) tunnel and a Mobile IP tunnel.

62. A system according to claim 61, wherein said interface entity provides packet routing functionality between said Gateway GPRS Support Node (GGSN) emulation module and said foreign agent emulation module.

63. The system of claim 60, wherein the interface entity further comprises:

an access, authorization, and accounting (AAA) emulation module connected to the access, authorization, and accounting (AAA) entity via a fifth interface, the access, authorization, and accounting (AAA) emulation module for providing an accounting function by interacting with an access, authorization, and accounting (AAA) of a home system for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

64. A system in which a user using simple IP roams into a visited system comprising a Serving GPRS Support Node (SGSN), the system comprising:

a home system, comprising: a home location register; an access, authorization, and accounting (AAA) entity; and an L2TP network server (LNS); and

an interface entity connecting the home system to the visited system to enable communication between the home system and the visited system, wherein the interface entity further comprises:

a visitor location register connected to the home location register via a first interface for enabling a user to register via the first interface; and

a home location register of a global system for mobile communications connected to the Serving GPRS Support Node (SGSN) via a second interface, the home location register for enabling a subscriber to register via the second interface;

a Link Access Control (LAC) emulation module connected to the L2TP network server via a third interface for supporting a bearer connection between the visited network and the home network via the third interface; and

a Gateway GPRS Support Node (GGSN) emulation module connected to said Serving GPRS Support Node (SGSN) via a fourth interface for supporting bearer connectivity between said visited network and said home network via said fourth interface by giving said visited system a Gateway GPRS Support Node (GGSN) emulation module and giving said system a normal routing interface, thereby providing packet routing functionality between said Gateway GPRS Support Node (GGSN) emulation module and said home system.

65. The system of claim 64, wherein the interface serves as an endpoint for a GPRS Tunneling Protocol (GTP) tunnel and an IPSec tunnel.

66. The system of claim 65, wherein the interface further comprises:

an access, authorization, and accounting (AAA) emulation module connected to the access, authorization, and accounting (AAA) entity via a fifth interface, the access, authorization, and accounting (AAA) emulation module to provide accounting functionality by interacting with access, authorization, and accounting (AAA) of a home system for L2TP authentication and 3GPP2 packet data accounting via the fifth interface.

67. An interface entity for enabling communication between a home system and a visited system comprising a Serving GPRS Support Node (SGSN) when a user using mobile IP roams to the visited system, wherein the home system comprises a home location register, an access, authorization and accounting (AAA) entity and a home agent, and wherein the interface entity comprises:

a home location register emulation module of a global system for mobile communications connected to the Serving GPRS Support Node (SGSN) via a first interface, the home location register emulation module for enabling a subscriber to register via the first interface; and

a visitor location register emulation module connected to the home location register via a second interface, the visitor location register emulation module for enabling a user to register via the second interface;

a foreign agent emulation module connected to the home agent via a third interface for supporting bearer connectivity between a visited interface entity and a home interface entity such that the foreign agent emulation module and a visited, authorized and accounting (AAA) emulation module are presented to the interface entity via the third interface; and

a Gateway GPRS Support Node (GGSN) emulation module connected to the Serving GPRS Support Node (SGSN) via a fourth interface, the Gateway GPRS Support Node (GGSN) emulation module being configured to support bearer connectivity between the visited system and the home system such that the visited system is presented with a Gateway GPRS Support Node (GGSN) emulation module via the fourth interface, wherein the interface entity provides packet routing functionality between the Gateway GPRS Support Node (GGSN) emulation module and the foreign agent emulation module and acts as an endpoint for a GPRS Tunneling Protocol (GTP) tunnel and a mobile IP tunnel.

68. The interface entity of claim 67, wherein the interface entity further comprises:

an access, authorization, and accounting (AAA) emulation module connected to the access, authorization, and accounting (AAA) entity via a fifth interface, the access, authorization, and accounting (AAA) emulation module for providing an accounting function by interacting with an access, authorization, and accounting (AAA) of a home system for mobile IP foreign agent challenge authentication and 3GPP2 packet data accounting.

69. An interface entity for enabling communication between a home system and a visited system comprising a Serving GPRS Support Node (SGSN) when a user using simple IP roams to the visited system, wherein the home system comprises a home location register, a visiting, authorization and accounting (AAA) entity and an L2TP network server (LNS), and wherein the interface entity comprises:

a visitor location register connected to the home location register via a first interface for enabling a user to register via the first interface;

a home location register of a global system for mobile communications connected to the Serving GPRS Support Node (SGSN) via a second interface, the home location register for enabling a subscriber to register via the second interface;

a Link Access Control (LAC) emulation module connected to the L2TP network server via a third interface for supporting a bearer connection between the visited network and the home network via the third interface; and

a Gateway GPRS Support Node (GGSN) emulation module connected to said Serving GPRS Support Node (SGSN) via a fourth interface for supporting bearer connectivity between said visited network and said home network via said fourth interface by giving said visited system a Gateway GPRS Support Node (GGSN) emulation module and giving said home system a normal routing interface, thereby providing packet routing functionality between said Gateway GPRS Support Node (GGSN) emulation module and said home system.

70. The interface entity of claim 69, wherein the interface entity acts as an endpoint for a GPRS Tunneling Protocol (GTP) tunnel and an IPSec tunnel.

71. The interface entity of claim 70, wherein the interface entity further comprises:

an access, authorization, and accounting (AAA) emulation module connected to the access, authorization, and accounting (AAA) entity via a fifth interface, the access, authorization, and accounting (AAA) emulation module to provide accounting functionality by interacting with access, authorization, and accounting (AAA) of a home system for L2TP authentication and 3GPP2 packet data accounting via the fifth interface.