Abstract:
A system and method for providing wireless Internet protocol access is provided. A network entity may be coupled to both a second generation and a third generation network access node. The network entity may intercept a request from a mobile node and determine whether the mobile node desires services from the second or third generation network. The network entity may then establish the proper communication session based on the type of session requested by the mobile node. By employing the network entity, service providers can effectively migrate from the second generation network architecture to the third generation architecture with minimal or no loss of services for users. Also, employing such a network entity enables users to operate a bi-functional mobile node, such as one that requires both second and third generation network access.

Description:
FIELD OF THE INVENTION 
   The present invention relates to communications in mobile Internet Protocol (“IP”) networks. More particularly, it relates to a method and system for IP wireless network access. 
   BACKGROUND 
   With the rapidly growing interest in wireless communications and Internet connectivity, wireless service providers are competing to capture the market share by offering their customers access to applications that take advantage of both technologies. However, as service providers attempt to widen their customer base, they are discovering inherent difficulties of providing combined voice and data services within circuit-switched networks. These infrastructures cannot meet the enormous demand for bandwidth or support timely, cost-effective delivery of emerging services and applications. 
   As the wireless market continues to grow at an increasing pace, service providers that rely on circuit-switched networks are facing mounting pressures since their systems cannot sustain increasing bandwidth requirements for new services and applications, and their networks lack the capacity to support the exponential rise in traffic. Such pressures put wireless network service providers at a disadvantage when they compete with other providers that have already begun to migrate to packet-based networks and thus are better prepared to respond quickly to market pressures. 
   To address these critical challenges, wireless data service providers are deploying next-generation data solutions that not only enable mobility, but also provide a framework for deploying emerging enhanced applications and services. First generation (“1G”) analog wireless systems were initially employed by wireless service providers to provide wireless service. But 1G systems have since been replaced by networks referred to as the second-generation (“2G”) wireless networks that provide increased speeds and capabilities.  FIG. 1  is a block diagram illustrating a network architecture  100  that is typically employed in 2G wireless networks. 
   Referring to  FIG. 1 , a client terminal  102  communicates over an air interface  104  with a Base Station Controller (“BSC”)  106 . The client device  102  may be a code division multiple access (“CDMA”) telephone having no Internet Protocol (“IP”) capability, or a different client device, such as a wireless fax device, for instance. The BSC  106  is in turn coupled via a communication link  108  to a Mobile Switching Center (“MSC”)  110 , which serves to connect calls between various points in a network. The communication link  108  may include a Primary Rate Interface (“PRI”) employing a plurality of communication and control channels, which are carried over T1 and/or E1 carrier lines. The MSC  110  is further connected by a voice data link  112  to a Public Switched Telephone Network (“PSTN”)  114 , which provides a path through which the MSC  110  may connect calls with a remote MSC and in turn with another client device, or a client device that may access the PSTN  114  via a modem connection  116 , such as a client terminal  118  illustrated in  FIG. 1 . 
   Further, as illustrated in  FIG. 1 , the MSC  110  is in turn coupled via a communication link  120  to an Interworking Function (“IWF”)  122 . The communication link  120  may include a Frame Relay (“FR”) communication link and/or a PRI, for instance. The IWF  122  is a hardware/software platform that serves as a gateway between a wireless network and a data packet network. The IWF  122  provides access to an IP network  126  and possibly the PSTN  114 . The IWF  122  may reside within a service provider&#39;s central office or switching center and may connect directly to wireless switches. As illustrated in  FIG. 1 , the IWF  122  is coupled to the IP network  126  via a communication link  124  including, for example, an IP over Ethernet communication link. The IP network  126  may further provide communication links to other network entities or client devices. As illustrated in  FIG. 1 , the IP network  126  is coupled via a communication link  128  to a network server  130 . 
   In the network architecture  100  illustrated in  FIG. 1 , processing of a call on the MSC  110  depends on call setup and management data received from the BSC  106 . If the call is identified as a regular voice call, then the MSC  110  may initiate Signaling System 7 (“SS7”) signaling to seize a trunk on an outgoing PRI to the PSTN  114 . However, if a call is identified as a data or fax call, the MSC  110  switches the call to the IWF  122  over the FR link  120 . Subsequently, the IWF  122  may convert the incoming circuit call into IP data packets that are sent to a destination via the IP network  126 . Alternatively, in some deployments, the data packets may be sent back to the MSC  110  that may send the data packets over the PSTN  114  as a regular modem call. 
     FIG. 2  is a block diagram illustrating typical layered protocol stacks  200  for network devices from the exemplary system  100  illustrated in  FIG. 1 . Many functions of the network devices may be performed by a protocol. Such functions range from the specification of connectors, addresses of the communications nodes, identification of interfaces, options, flow control, reliability, error reporting, synchronization, etc. A set (also known as suite or stack) of protocols to carry out such functions is defined in  FIG. 2  for the network devices. Each protocol in the suite handles one specific aspect of the communication. Lower (network) layers of the suite are primarily designed to provide a connection or path between users to hide details of underlying communications facilities, and upper (or higher) layers of the suite ensure that data is exchanged in correct and understandable form. A transport layer provides the connection between the upper (applications-oriented) layers and the lower (or network-oriented) layers. 
   The layered protocol stacks in  FIG. 2  are described with respect to Internet Protocol suites comprising from lowest-to-highest, a physical, a link, a network, a transport, and an application layer. However, more or fewer layers could also be used, and different layer designations could also be used for the layers in the protocol stacks  200  (e.g., layering based on the seven layer Open System Interconnection (“OSI”) model as developed by the International Organization for Standardization (“ISO”)). 
   The layered protocol stacks are used to connect network devices to underlying physical transmission medium including a wireless network, a wired network, a wireless area network (“WAN”) or a wired local area network (“LAN”), for instance. However, other computer networks could also be used. 
     FIG. 2  illustrates a client device  250 , such as a personal computer, a telephone  252 , the MSC  110 , and the IWF  122 . As is known in the art, a physical layer defines electrical and physical properties of an underlying transmission medium. The physical layer on the client device  250  includes an RS 232   202  that is used to connect the client device  250  to a physical layer including RS 232   212  on the telephone  252 . The physical link on the telephone  252  may also include a radio link protocol (“RLP”) layer  214  that is used to connect to an RLP layer  224  on the MSC  110 . In turn, the physical layer on the MSC  110  may also include a frame relay switched virtual circuit (“FRSVC”)  226  layer including T1 or E1 links for connecting to the physical link including an FRSVC  236  on the IWF  122 . 
   A link layer is used to connect network devices to the underlying physical transmission medium or physical layer. The link layer includes a Point-to-Point Protocol (“PPP”) layer defining an Internet standard for transmission of IP packets over serial lines. The client device  250 , the telephone  252 , the MSC  110 , and the IWF  122  include PPP layers  204 ,  216 ,  228 , and  238 , respectively, as their link layers. The IWF  122  further includes an Ethernet layer  240  (“ETH”) for connecting to an IP network. However, it should be understood that other link layer protocols, such as a Medium Access Control (“MAC”) protocol or IEEE 802.x protocols, could also be used. 
   Above the link layer, there is a network layer (also called the “Internet Layer” for Internet Protocol suites). The network layer includes an IP layer. Specifically, the client device  250 , the telephone  252 , the MSC  110 , and the IWF  122  include IP layers  206 ,  218 ,  230 , and  242 , respectively. 
   Above the network layer, there is a transport layer. The transport layer includes a Transmission Control Protocol (“TCP”) layer, for instance. The devices illustrated in  FIG. 2  include TCP layers  208 ,  220 ,  232 , and  244 , respectively. The TCP provides a connection-oriented, end-to-end reliable protocol designated to fit into a layered hierarchy of protocols, which support multi-network applications. TCP provides reliable inter-process communication between pairs of network devices attached to distinct but interconnected networks. However, it should be understood that the transport layer may also include a User Datagram Protocol (“UDP”). 
   Above the transport layer, there is an application layer including application programs. The network devices illustrated in  FIG. 2  include application layers (“APP”)  210 ,  222 ,  234 , and  246 , respectively. The application programs provide desired functionality to a network device (e.g., telephony or other communications functionality). For example, application programs may provide voice, video, audio, data or other applications. The application layer protocol may also include application protocol layers. Application protocol layers typically provide a subset of the functionality provided by an application program. 
   The application layer may include a Dynamic Host Configuration Protocol (“DHCP”) application program or application protocol layer. DHCP is a protocol for passing configuration information such as IP addresses to network devices. The application layer may also include a Service Location Protocol (“SLP”) application program or application protocol layer. As is known in the art, SLP provides a scalable framework for discovery and selection of network services. Additionally, the application layer may also include a Session Initiation Protocol (“SIP”) application program or application protocol layer. SIP is an application layer control (signaling) protocol for creating, modifying and terminating sessions with one or more participants. The application layer may also include an ITU-T H.323 or H.324 application programs or application protocol layers. H.323 is the main family of video conferencing recommendations for IP networks. H.324 is a video conferencing recommendation using Plain-Old-Telephone Service (“POTS”) lines. The application layer may also include a Voice-over-IP (“VoIP”) application program or application protocol layer. VoIP typically comprises several application programs (e.g., H323, SIP, etc.) that convert voice signals into a stream of packets that may then be sent to a packet network. 
   While today&#39;s 2G wireless networks carry voice, limited data applications and provide short messaging services, next generation or third-generation (“3G”) networks offer much greater capacity and significantly higher data rates, enabling service providers to offer enhanced data applications that go beyond traditional wireless e-mail and Internet access.  FIG. 3  is a block diagram illustrating a network architecture  300  that is typically used in 3G networks. 
   Referring to  FIG. 3 , a client device  302  communicates with a client device  334  on an IP network  318  by means of three devices; a Radio Access Node (“RAN”)  310 , a Packet Data Serving Node (“PDSN”)  314  and a home agent node  322 . The client device  302  is coupled to the PDSN  314  via an air interface  304 , a base station  306  and a communication link  308 . The client device  302  may be a CDMA capable telephone having IP capability. In such an embodiment, the client device  302  may transmit PPP packets over the air interface  304  to the radio access node  310  that may encapsulate the received packets and forward them to the PDSN  314  via a communication link  312 . The PDSN  314  performs traffic aggregation and acts as a foreign agent for mobile IP functionality. 
   As illustrated in  FIG. 3 , the PDSN  314  is further coupled to the IP network  318  via a communication link  316 , and the IP network  318  is coupled to the home agent  322  via a communication link  320 . The home agent  322  serves as an edge router, directing traffic to mobile client devices via foreign agents located within a service provider&#39;s network. Further, as illustrated in  FIG. 3 , the network  300  includes an Authentication, Authorization and Accounting (“AAA”) server  332 , such as a Remote Authentication Dial-In User Service (“RADIUS”) server. As is known in the art, RADIUS enables remote access servers to authenticate users and to authenticate their access to the requested system or service. The AAA server  332  may reside on a visited (foreign) network or a home network. The PDSN  314  may employ the AAA server  332  to perform authentication during establishment of PPP sessions with mobile terminals. The PDSN  314  may also interact with the AAA server  332  during a mobile IP registration process. 
   Referring back to  FIG. 3 , the network architecture  300  further includes a media gateway  326  connected to the IP network via a communication link  324 , and further connected to a PSTN  330  via a communication link  328 . The media gateway  326  converts IP packets to standard voice calls for VoIP calls terminating on the PSTN  330 . 
   As system providers migrate their equipment from 2G to 3G networks, they often need to replace many components and redesign their network architectures. Thus, a need exists for a system and method for supporting 2G to 3G network migration. 
   SUMMARY 
   In an exemplary embodiment, a method and system for providing wireless Internet protocol access is provided. The method may include, at a network entity that is configured to communicate with a first type of wireless access architecture and a second type of wireless access architecture, receiving a communication session request from a mobile node. The method further includes, at the network entity, determining a type of a communication session associated with the communication session request and establishing the communication session between the mobile node and either the first type of wireless access architecture or the second type of wireless access architecture based on the type of the communication session. For example, the network entity may establish the communication session between the mobile node and either a 2G or a 3G wireless network. 
   In another respect, the method may include, at a network entity that is configured to communicate with a first type of wireless access architecture and a second type of wireless access architecture, receiving a communication session request from a mobile node and determining if the communication session request is a voice communication session request. If so, the method may include sending a voice communication session request from the first network entity to a mobile switching center to establish a voice communication session between the mobile node and the first type of wireless access architecture. And if the communication session request is not a voice communication session request, the method may include determining that the communication session request is a data communication session request and sending the data communication session request from the first network entity to a data access node to establish a data communication session between the mobile node and the second type of wireless access architecture. 
   In still another respect, the exemplary embodiment may take the form of a network entity that may establish communication sessions in mobile Internet Protocol networks. The network entity may comprise a first switch configured to communicate with a first type of access node that is associated with a first type of wireless access architecture. The first switch may also be configured to receive a first communication session request from a first mobile node via the first type of access node. The network entity may also comprise a second switch coupled to the first switch and configured to communicate with a second type of access node that is associated with a second type of wireless access architecture. The network entity may receive the first communication session request, which has a communication type identifier, and determine if the communication type identifier is a first communication type. And if so, the first switch may establish a first communication session between the first mobile node and the first type of wireless access architecture. If the communication type identifier is a second communication type, the first switch may direct the second switch to establish a second communication session between the first mobile node and the second type of wireless access architecture. 
   In yet another respect, the exemplary embodiment may take the form of a system for providing wireless Internet protocol access. The system may include a first type of wireless access architecture configured to provide a first type of communication service and a second type of wireless access architecture configured to provide a second type of communication service. The system may further include a network entity coupled to the first and second type of wireless access architectures. The network entity may receive a communication session request from a mobile node and determine a type of a communication session associated with the communication session request. The network entity may then establish the communication session between the mobile node and either the first or second type of wireless access architecture based on the type of the communication session. 
   These as well as other aspects and advantages will become more apparent to those of ordinary skill in the art by reading the following detailed description, with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the present invention are described with reference to the following drawings, in which: 
       FIG. 1  is a block diagram illustrating a typical 2G network architecture; 
       FIG. 2  is a block diagram illustrating a typical layered protocol stacks for network devices from the network illustrated in  FIG. 1 ; 
       FIG. 3  is a block diagram illustrating a typical 3G network architecture; 
       FIG. 4  is a block diagram illustrating an exemplary network architecture for providing IP wireless network access according to one exemplary embodiment of the present invention; 
       FIG. 5  is a block diagram illustrating a network entity for providing wireless access in a mobile IP network according to one exemplary embodiment of the present invention; 
       FIG. 6  is a flowchart depicting functional blocks according to one exemplary embodiment of the present invention; 
       FIG. 7  is a block diagram illustrating an exemplary embodiment of a network access architecture illustrating protocol interfaces that may be used for providing wireless access in a mobile IP network according to one embodiment of the present invention; 
       FIG. 8  is a block diagram illustrating exemplary layered protocol stacks for network devices from the exemplary network illustrated in  FIG. 7 ; 
       FIG. 9  is a block diagram illustrating a message sequence scenario for providing wireless network access in a network architecture using a hybrid switch according to one exemplary embodiment of the present invention; and 
       FIG. 10  is a block diagram illustrating another message sequence scenario for providing wireless network access in a network architecture using a hybrid switch according to one exemplary embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     FIG. 4  is a functional block diagram illustrating an embodiment of a system  400  suitable for providing IP wireless access for client devices. It should be understood that this and other arrangements and processes described herein are set forth for purposes of example only, and other arrangements and elements (e.g., interfaces, functions, order of elements, etc.) can be used instead and some elements may be omitted altogether. Further, as in most telecommunications applications, those skilled in the art will appreciate that many elements described herein are functional entities that may be implemented as discrete components or in conjunction with other components, in any suitable combination or location. 
   As shown in  FIG. 4 , the system  400  includes a first mobile node  402 , a second mobile node  420 , a BSC  404 , a RAN  406 , and a network entity  408  including a hybrid switch  410  and a 2G/3G PDSN  412  with an IWF function  413 . The hybrid switch  410  and the PDSN  412  are interconnected through an A10 and A11 Ethernet interface  409 . The system  400  further includes an MSC  414 , a PSTN  416 , and an IP network  418 . And the PDSN  412  is connected to the MSC  414  through a PRI interface  415 . 
   In one embodiment, components of the exemplary system may be implemented using equipment form Commworks (a 3Com company). For example, the exemplary system  400  may include a Total Control Hub including Commworks Total Control Hub 1000 or 2000, and Total Control 1000 or 2000 Packet Data Serving Node Set. However, the exemplary embodiments are not limited to such equipment, and the exemplary system  400  could also be implemented using equipment from Cisco Systems of San Jose, Calif.; Lucent Technologies of Murray Hill, N.J.; Motorola, Inc. of Schaumburg, Ill.; Nokia Corporation of Helsinki, Finland, and others. 
   The first mobile node  402  communicates via a radio communication link  420  with a first type of access node, the BSC  404 . BSC  404  is an interface between Base Transceiver Stations (“BTS”) (not shown) and the PSTN  416 . The system  400  may include many BTSs, which include one or more antennas arranged to produce radiation patterns to provide the link  420  with the BSC  404 . BSC  404  also may handle radio resource management and radio network management functions for BTSs. According to an exemplary embodiment, the first type of access node (i.e., the BSC  404 ) is associated with a first type of wireless network, specifically a 2G wireless network. However, it should be understood that different embodiments are possible as well. 
   The second mobile node  420  communicates via a radio communication link  422  with a second type of access node, the RAN  406 . The RAN  406  may include a BTS (or any other wireless access point) coupled to either a BSC or a packet control function (“PCF”), which selects a PDSN for new incoming communication sessions. The mobile node  420  can communicate via the radio communication link  422  to the BTS, which may connect to the BSC or PCF via a wired link. The BSC or PCF may then couple to a foreign agent, such as PDSN  412 , over a generic route encapsulation (“GRE”) tunnel such as a radio-protocol (“R-P”) interface. (For more information on GRE see request for comments (RFCs)  1701 – 1702 , the full disclosures of which are incorporated herein by reference). The R-P interface may comprise an A10 interface, which is used to transfer data by encapsulating data into GRE packets, and an A11 interface, which defines signaling procedures for managing A10 connections. (A-11 messages are based on mobile IP registration messages as defined in the Telecommunications Industry Association/Electronics Industries Alliance/Interim Standard 2001 (TIA/EIA/IS-2001), the full disclosure of which is incorporated herein by reference). According to an exemplary embodiment, the second type of access node (i.e., RAN  406 ) is associated with a second type of wireless network, specifically a 3G wireless network. 
   The mobile nodes  402  and  420  may take any suitable forms, such as, for instance, a telephone, a laptop computer, a fax, a wireless modem, or a personal digital assistant (“PDA”), for instance. According to an exemplary embodiment, the mobile node  402  may be a 2G-capable CDMA mobile node, and the mobile node  420  may be a 3G-capable CDMA mobile node. However, it should be understood that, in an alternative embodiment, the mobile node  402  or  420  may be a dual (2G- and 3G-capable) CDMA mobile node. 
   The BSC  404  and the RAN  406  may reside on the same radio network, such as the same CDMA radio network, or different radio networks, such as within two different CDMA radio networks. The BSC  404  and the RAN  406  are coupled to the network entity  408  via communication links  424  and  426 , respectively. The communication link  424  may be a T1/PRI link, and the communication link  426  may be an R-P link. 
   The network entity  408  is further connected via a communication link  428  to the MSC  414  that is connected to the PSTN  416  via a communication link  432 . The network entity  408  is also connected to an IP network  418  via a communication link  430 . The communication links  428  and  432  may be PRI communication links, and the communication link  430  may be an IP communication link. 
   The network entity  408  includes the hybrid switch  410  and the 2G/3G PDSN  412 . The hybrid switch  410  and the 2G/3G PDSN  412  may be application cards within the network entity  408 . The hybrid switch  410  and the 2G/3G PDSN  412  may function as switches within the network entity  408  that routes incoming calls to a desired endpoint. Therefore, the network entity  408  may operate as a central control point to route incoming calls to the proper or desired destination. According to an exemplary embodiment, the network entity  408  is configured to communicate with both the first type of access node (BSC  404 ) and the second type of access node (RAN  406 ) and may receive communication session requests transmitted from mobile nodes via one of these access nodes. Further, according to an exemplary embodiment, when the network entity  408  receives a communication session request from mobile nodes  402  or  420 , as will be described in greater detail below, the network entity  408  may determine a type of the requested communication session and may process the request based on the type of the request. For instance, when the network entity  408  receives a typical voice communication session request from the mobile node  402  via the BSC  404 , the network entity  408  may send the request to the MSC  414 . And when the network entity  408  receives a communication request from the mobile node  420  via the RAN  406 , the network entity may establish a communication session with the IP network  418 . In an embodiment in which the network entity  408  receives a data call request from the mobile node  402 , the network entity  408  may offload data call processing from the MSC  414 , the embodiments of which will be described in greater detail below. 
   According to an exemplary embodiment, the hybrid switch  410  monitors and relays signaling information between call control functions of the BSC  404  and mobility management functions of the MSC  414 , and manages T1/T3 resources between the BSC  404  and the MSC  414 . For example, T1 connections comprise DS1 signals, which include 24 DS0 (64 Kbps) signals transmitted using pulse-code modulation (PCM) and time-division multiplexing (TDM) and a T3 connection comprises 28 T1-lines. And the hybrid switch  410  may control routing of the signals through these T1/T3 connections. Further, the hybrid switch  410  can transmit user data directly from the BSC  404  to the 2G/3G PDSN  412  through the interface  409  to allow IP network  418  access to mobile node  402 , which would normally be routed through the MSC  414  to the IP network  418 . 
   The 2G/3G PDSN  412  may terminate PPP links of communication sessions from either 2G or 3G mobile nodes as well as TCP links for 2G asynchronous data communication sessions. Further, 2G/3G PDSN  412  may manage accounting and authentication of 2G and 3G users. 
   For a 3G user, such a mobile node  420 , the network entity  408  may route a call as it normally would be routed if the entity were absent. The network entity  408  receives the call through the PDSN  412 , which performs data encapsulation (and initiates tunnel registration with a home agent node if applicable), in order to send the call to the IP network  418 . Similarly, for a 2G user such as mobile node  402 , the network entity  408  will route a voice call as it normally would be routed if the network entity  408  were absent. However, the network entity  408  will route a 2G data call around the MSC  414  to the IP network  418  by sending the call to the PDSN  412 , which in turn establishes a connection with the IP network  418 . 
     FIG. 5  is a block diagram illustrating a detailed view of a network entity  500 , which provides wireless access in a mobile IP network, such as network entity  408  in  FIG. 4 , according to one exemplary embodiment. The network entity  500  includes a call processing switch  502 , a media gateway controller/SIP proxy  504 , a media gateway  506 , a digital signal processing (“DSP”) modem  508 , an IP egress foreign agent  510 , and a 2G/3G PDSN  512  which has an IWF function  513 .  FIG. 5  illustrates the 2G/3G PDSN  512  and the call processing switch  502  located in the same network entity  500 . However, it should be understood that in an alternative embodiment, the call processing switch  502  and the 2G/3G PDSN  512  may be located on two discrete physical network entities. Further, it should be understood that the network entity  500  might also include management and route server application cards as well as interfaces to other network services such as AAA services. Moreover, functions of each of the components of the network entity  500  may be performed by a processor executing machine language instructions programmed to carry out the functions. 
   The call processing switch  502  includes input T1/FRSVC/PRI interfaces to one or more BSCs and an output PRI interface to one or more MSCs. The call processing switch  502  receives incoming communication requests from the BSC and if appropriate (as described below), routes the request directly to the MSC. The call processing switch  502  is connected to the media gateway controller/SIP proxy  504 , which creates proxy messages to allow the network entity  500  to proxy requests through the media gateway  506  to an MSC via digital signal links (“DSx”). For instance, if the call processing switch  502  receives a request for a data call, the call processing switch  502  will send the call to the IWF  513  and also initiate a signaling connection with an MSC through the media gateway controller  504 . 
   The 2G/3G PDSN  512  terminates an input R-P interface from one or more RANs and an output IP interface to an IP network via the IP egress/FA  510 . The DSP modem  508  converts calls from the PDSN  512  into IP packets to be routed to a data packet transport network using any known data encapsulation technique, such as GRE data encapsulation. 
     FIG. 6  is a flowchart generally depicting a method  600  for establishing communication sessions in mobile IP networks using the network entity  500 . As shown at block  602 , the call processing switch  502  may receive a communication request from a mobile node. For example, the call processing switch  502  may detect and receive a new incoming communication session on the input T1/PRI interface. As shown at block  604 , the call processing switch  502  then determines a type of communication session associated with the communication request. For example, the call processing switch  502  may determine if the incoming session is a data or voice session, such as a 2G voice or a 3G data session, possibly by reading an integrated services digital network (“ISDN”) B channel of the T1/PRI interface. (The T1/PRI interface is a form of high bandwidth signaling that splits a single telephone line into 24 channels. Twenty-three channels are used for “actual traffic” and the remaining channel is devoted to signaling information. The channels on which traffic is carried are referred to as “B” channels. The channel devoted to signaling is referred to as the “D” channel. This means that, in terms of voice lines, 23 conversations can be held simultaneously over the same physical line.) 
   As shown at block  606 , the call processing switch  502  determines if the type of communication session is a voice or data session. For example, as mentioned above, the call processing switch  502  can read the B channels of the T1/PRI interface to determine if voice or data is being sent by reading an identifier within the request or possibly by determining if the information being sent is characteristic of a voice or data call (e.g., voice calls may have less actively than data calls). In addition, the communication request may include a service option field with an identifier to distinguish between different types of calls and using that field, the call processing switch  502  may determine which type of call is being requested. 
   As shown at block  608 , if the type of communication session is a data session, the call processing switch  502  routes the call to the IP network. For example, the call processing switch  502  may route the call to the IWF  513  of the PDSN  512 , which converts the data call into IP packets and routes the IP packets to the IP egress/FA  510  to be sent to the IP network. As shown at block  610 , if the type of communication session is a voice session, the call processing switch  502  routes the call to the MSC. For example, the call processing switch  502  may route the call to the output PRI interface that connects the call to an MSC. 
   Similarly, the 2G/3G PDSN  512  may detect and receive a new incoming communication session request on the input R-P interface. According to one exemplary embodiment, when the 2G/3G PDSN  512  detects an incoming VoIP communication session, the 2G/3G PDSN  512  may transmit the VoIP communication session via the media gateway  506  onto the DSx links, such as DS1 or DS3 links, for instance. The DSx links may then connect to the SS7 network to connect to the PSTN. Further, when the 2G/3G PDSN  512  detects an incoming data communication session, the 2G/3G PDSN  512  may route incoming data packets via the IP egress  510  to the IP network. 
     FIG. 7  is a block diagram illustrating an exemplary embodiment of network access architecture  700  illustrating protocol interfaces that may be used in operation of the network entity  500  for providing wireless access in a mobile IP network. 
   The network access architecture  700  includes a first type of access device, a BSC  702 , and a second type of access device, a RAN  706  including a PCF (not shown), a BTS  704 , a 2G/3G PDSN  708 , a hybrid switch  710 , and an MSC  712  including a call control mobility management unit  714  and a switching unit  716 . The BTS  704  and the RAN  706  may use A8 and A9 interfaces to communicate. The A8 interface may provide a path for user traffic between the BTS  704  and the RAN  706  and between BTSs (not shown) and a BSC. According to one embodiment, the A8 interface may carry data encapsulated using GRE, IP, link layer, or physical layer protocols. The A9 interface may provide a path for transmitting signaling information between the BTS  704  and the RAN  706  and between BTSs and a BSC. The A9 interface may carry data encapsulated using a TCP/UDP, IP, link layer, or physical layer protocols. 
   The RAN  706  may then communicate with the 2G/3G PDSN  708  via interfaces defined as A10 and A11. The A10 interface may be used to provide a path for user traffic and may carry data encapsulated using GRE, IP, link layer, or physical layer protocols. The A11 interface may be used to provide a path for signaling information and may carry data encapsulated using UDP, IP, link layer, or physical layer protocols. The 2G/3G PDSN  708  and the hybrid switch  710  also communicate via the A10 and A11 interfaces. According to an exemplary embodiment, the A10 interface between the hybrid switch  710  and the 2G/3G PDSN  708  may be a LAN/WAN based IP interface that the hybrid switch  710  may use to carry user data from the BSC  706  to an IWF function located on the 2G/3G PDSN  708 . Further, the A11 interface may also be a LAN/WAN based IP interface, and the hybrid switch  710  may use this interface to carry signaling information from the MSC  712  to the IWF function on the 2G/3G PDSN  708 . 
   The BSC  702  and the hybrid switch  710  may communicate via A1, A2, and A5 interfaces. Similarly, the hybrid switch  710  may communicate with the call control mobility management  714  via the A1 interface. The A1 interface may be used to carry signaling information between the call control and mobility management function  714  on the MSC  712  and the BSC  702 . The A1 interface may carry data encapsulated using signaling connection control part (“SCCP”) protocol, IOS application protocols, physical layer protocols, or multicast transport protocols (“MTP”), such as MTP 1 , MTP 2 , or MTP 3 . The A2 interface may carry PCM (voice/data) encoded data and provides an interface between the hybrid switch  710  and the BSC  702 . The A5 interface between the BSC  702  and the hybrid switch  710  may be used to carry data for 2G data communication sessions. The A5 interface may carry data octet streams or intersystem link protocol (“ISLP”). 
   Other interfaces may be used as well between entities of the network access architecture  700 . For example, an A3 interface may be used to carry coded user information (voice/data) and signaling information between the hybrid switch  710  and the BSC  702 . The A3 interface is composed of two parts: signaling and user traffic. The signaling information may be carried across a separate logical channel form the user traffic channel to control the allocation and use of channels for transporting user traffic. Additionally, an A7 interface may be used to carry signaling information between the BTS  704  and the RAN  706 . 
   The information transmitted between entities of  FIG. 7  may vary according to a specific implementation. As one example, information such as a type of the call (carried in a service option of a request), an actual speed of the call (e.g., service options are intended to represent the data speeds but the actual speed supported at the time a call is setup could be different), phone numbers (calling, callers etc.), additional Call Reference Values (“CRV”) could be carried for call identification, or mobile equipment identifiers like Electronic Serial Numbers (“ESN”) etc. could be sent between the entities. 
   Additionally, the A5 interface may exist between the hybrid switch  710  and the MSC  712  (not shown) to communicate data. For a standard 2G data call, data flows from the mobile node to the BSC (via BTS) to the MSC and then to IWF and beyond. However here, in one embodiment, the hybrid switch  710  may offload data traffic from the MSC  712 . The hybrid switch  710  may monitor the signaling information that is exchanged between the BSC  702  and the MSC  712 . And during an offload situation, the hybrid switch  710  may only send the call setup information to the MSC  712  on the A1 link and the actual data is sent to the 2G/3G PDSN (or IWF function) after it is received from the BSC  702  so that it can be routed to the IP network more efficiently rather than traveling through the PSTN. Alternatively, the hybrid switch  710  may not send any setup information to the MSC  712  if the call is a data call. The A1 interface between the hybrid switch  710  and the MSC  712  therefore, may be omitted. The hybrid switch  710  may monitor the A1 messaging to determine what physical links the call data will travel from the BSC  702 . This may require cooperation from the MSC  712  so that the MSC  712  is aware of that the control and data planes are split and the MSC  712  is now handling only the A1 links and not the A5 links (e.g., the links carrying data). 
   Offloading traffic from MSCs may be beneficial since a service provider may be unable to add new subscribers to their 2G networks due to overloaded MSCs. The hybrid switch  710  could proxy voice calls onto the PSTN (when they do not contain data) and offload the data call processing from the MSCs onto the 2G/3G PSDN. The MSC can still be aware that the call is setup since it will receive signaling information (through the A1 interfaces), however data can be routed by the hybrid switch  710  around the MSC. Alternatively, signaling information does not have to be sent to the MSC when offloading a data call because the call is not routed through the MSC. 
   An A5 link may not exist between the MSC  712  and the hybrid switch  710 , since data calls can be offloaded from the MSC, except for asynchronous data or fax calls where the IWF may dial out to a PSTN network to complete the call because in such an instance, a PRI link to the MSC  712  may be necessary to reach the PSTN network. In this scenario, the MSC  712  only terminates the PSTN links (which is half of the call) and the hybrid switch  712  still offloads the other half of the call from the MSC  712 . Without offloading, data would flow from the mobile node to the MSC  712  through a BTS and then possibly to an IWF. However, employing the offloading technique, data only travels from a mobile node to a BTS to the hybrid switch  710  and then to the IWF or PDSN  708 . Other types of calls that may typically be routed through the MSC may not require a PSTN connection and, in those cases, the hybrid switch  710  may completely offload the MSC  712 . 
     FIG. 8  is a block diagram illustrating exemplary layered protocol stacks  800  for the hybrid switch  710 , which may define signaling between the hybrid switch  710  and other entities of the network access architecture  700 . For example, the layered protocol stacks  800  may define connections, signaling and applications of the A1, A2, A5, A8, A9, A10, and A11 interfaces. The layered protocol stacks are described with respect to IP suites comprising, from lowest to highest, a physical layer  804 , a link layer  806 , a network layer  808 , a transport layer  810 , and an application layer  812 . However, it should be understood that more or fewer layers could also be used, and different layer designations could also be used for the layers in the protocol stacks  800 . 
   The layered protocol stacks are used to connect network devices to underlying physical transmission medium including a wireless network, a wired network, a WAN or a LAN, for instance. However, other computer networks could also be used. 
   The physical layer  804  on the mobile node  701  includes an RS 232   814  connection or an RLP  816  connection that is used to connect to an RLP  818  on the BSC  702 . The physical layer on the BSC  702  also includes a T1/ISLP  820  that is used to connect to an ISLP  822  on the hybrid switch  710 . The physical layer on the hybrid switch  710  further includes Ethernet/GRE layer  824  that is used to connect to a GRE layer  826  on the 2G/3G PDSN  708 . The link layer  806  on the illustrated devices includes PPP layers  828 ,  830 ,  832 , and  834 . The network layer  808  on the devices includes IP layers  836 ,  838 ,  840 , and  842 . The transport layer  810  includes TCP layers  844 ,  846 ,  848 , and  850  on the illustrated devices, and the application layer  812  includes application programs  852 ,  854 ,  856 , and  858 . 
   In addition to DHCP, SLP, SIP, H.323, and H.324, the application layers may also include a Domain Name System (“DNS”) application program or application protocol layer. The DNS provides replicated distributed secure hierarchical databases that hierarchically store resource records under domain names. The application layers may also include an AAA application program or application protocol layer. AAA includes a classification scheme and exchange format for accounting data records. The application layers may also include a Simple Network Management Protocol (“SNMP”) application program or application protocol layer. SNMP is used to support network management functions. 
     FIG. 9  is a block diagram illustrating a message sequence scenario  900  (i.e., a sample call flow model) for providing wireless network access in a network architecture using a hybrid switch within the network access architecture  700 . The message sequence scenario  900  illustrates a 2G voice and data call setup and communication. 
   Initially, at step  902 , assume the mobile node  701  communicates with the BSC  702  to set up RF resources. The mobile node  701  may send an origination message over an access channel of the air interface to the BSC  702 , and the BSC  702  may acknowledge the receipt of the origination message with a base station acknowledgement order message to the mobile node  701 . And if the BSC  702  can determine that resources, e.g., a traffic channel, are not available, the BSC  702  can decline the origination message. 
   At step  904 , the BSC  702  communicates with the hybrid switch  710  to set up RF resources through the A1 signaling interface. The BSC  702  may construct a service request message and send it to the hybrid switch  710 . At step  906 , the hybrid switch  710  sends an A1 bearer channel setup message to the MSC  712 . According to an exemplary embodiment, the A1 message includes a request to allocate physical T1 or T3 resources. Further, the A1 message may specify a type of communication session being setup for the mobile node  701 . According to one exemplary embodiment, the communication session for mobile node  701  is a 2G voice and data call. 
   At step  908 , the MSC  712  sends an A1 bearer channel setup reply message to the hybrid switch  710 . According to an exemplary embodiment, the A1 reply message identifies a T1 channel that was allocated for the incoming session. Alternatively, if an authentication failure occurred, because of a malicious mobile node operating on the network without authorization, then the MSC  712  may simply clear or drop the call. At step  910 , the mobile node  701  and the MSC  712  can communicate through an A2 interface to send and receive voice information. And, at step  912 , the mobile node  701  and the MSC  712  can also communicate through an A5 interface to send and receive data. 
     FIG. 10  is another block diagram illustrating a message sequence scenario  1000  for providing wireless network access in a network architecture using a hybrid switch within the network access architecture  700 . The message sequence scenario  1000  illustrates an instance where in the past, the MSC  712  would normally handle the call, however using the hybrid switch  710  according to embodiments of the present invention, the call can be offloaded from the MSC  712 . Initially, at step  1002 , assume the mobile node  701  communicates with the BSC  702  to set up RF resources, such as through a paging channel within a CDMA system. In one embodiment, the mobile node  701  may send an origination message over an access channel of the air interface to the BSC  702 , and the BSC  702  may acknowledge the receipt of the origination message with a base station acknowledgement order message to the mobile node  701 . And if the BSC  702  can determine that resources, e.g., a traffic channel, are not available, the BSC  702  may decline the origination message. 
   At step  1004 , the BSC  702  communicates with the hybrid switch  710  to set up RF resources. The BSC  702  may construct a service request message and send it to the hybrid switch  710 . Messaging may not be needed between the mobile node  701  and the hybrid switch  710  for setting up the RF resources because that is handled by the BSC  702  in conjunction with MSC  712  for authorization and authentication of the mobile node  701 . This can be done using an A1 link between the BSC  702  and the MSC  712 . 
   At step  1006 , the BSC  702  sends an A1 bearer channel setup message to the MSC  712 . According to an exemplary embodiment, the BSC  702  sends the A1 setup message via the hybrid switch  710 , and the A1 message includes a request to allocate physical T1 or T3 resources. Further, the A1 message may specify a type of communication session being setup for the mobile node  701 . According to one exemplary embodiment, the communication session for mobile node  701  is a 2G data call. When the hybrid switch  710  detects the A1 bearer channel setup message  1006 , the hybrid switch  710  sends an A11 setup message  1008  to the 2G/3G PDSN  708 . The hybrid switch may know which PDSN to send the A11 messages to by using a table of configured PDSN identifiers and to create an error control identifier with the mobile node&#39;s international mobile subscriber identity (IMSI) to choose one of them. In another embodiment, the hybrid switch  710  may query a foreign agent control node (FACN) that manages the available PDSNs and returns the IP address of an available PDSN in an initial A11 reply that the hybrid switch  710  could use to establish the A10 tunnel/PPP link. 
   At step  1010 , the MSC  712  sends an A1 bearer channel setup reply message to the BSC  702 . According to an exemplary embodiment, the A1 reply message is sent via the hybrid switch  710  and identifies a T1 channel that was allocated for the incoming session. Alternatively, if an authentication failure occurred, because of a malicious mobile node operating on the network without authorization, then the MSC  712  may simply clear or drop the call. 
   At step  1012 , the 2G/3G PDSN  708  sends an A11 setup reply message to the hybrid switch  710 . The reply message may indicate that the call has been properly routed to the IP network. 
   At step  1014 , the MN  701  and the 2G/3G PDSN  708  use an Ethernet link to negotiate PPP parameters for the communication session. At step  1016 , the mobile node  701  and the 2G/3G PDSN  708  set up TCP/IP resources and, at step  1018 , a 2G data call communication session is established between the mobile node  701  and the 2G/3G PDSN  708 , efficiently offloading the data call from the MSC  712 . 
     FIGS. 9 and 10  illustrate examples of how a network entity may determine a type of a communication session requested by the mobile node  701 . In the example illustrated in  FIG. 9 , the hybrid switch  710  determined that the mobile node  701  requested 2G network access, therefore the hybrid switch  710  setup a communication link between the mobile node  701  and the MSC  712 . However, had the mobile node  701  made a request for 3G network access, the hybrid switch  710  may determine such and establish a communication link between the mobile node  701  and the PDSN  708 . Alternatively,  FIG. 10  illustrates an example where the hybrid switch  710  determined that mobile node  701  requested 2G data access, therefore, the hybrid switch  710  sent the call via an A10 and A11 interface to the PDSN  708  to establish a connection between the mobile node  701  and the IP network. 
   A gradual upgrade from a 2G network to a 3G network can be done with the implementation of the hybrid switch as described within the present invention. As the 3G network is being built out, the hybrid switch allows for a carrier to migrate a hardware platform from a 2G network to a 3G network simply by replacing an application card within a network entity. 
   It should be understood that the programs, processes, methods and systems described herein are not related or limited to any particular type of computer or network system (hardware or software), unless indicated otherwise. Various types of general purpose or specialized computer systems supporting the IP networking may be used with or perform operations in accordance with the teachings described herein. 
   In view of the wide variety of embodiments to which the principles of the present invention can be applied, it should be understood that the illustrated embodiments are examples only, and should not be taken as limiting the scope of the present invention. For example, the steps of the flow diagrams may be taken in sequences other than those described, more or fewer steps may be used, and more or fewer elements may be used in the block diagrams. While various elements of the preferred embodiments have been described as being implemented in software, in other embodiments in hardware or firmware implementations may alternatively be used, and vice-versa. 
   Further, it will be apparent to those of ordinary skill in the art that methods involved in the system for packet session control may be embodied in a computer program product that includes a computer readable medium. For example, a computer readable medium can include a readable memory device, such as a hard drive device, CD-ROM, a DVD-ROM, or a computer diskette, having computer readable program code segments stored thereon. The computer readable medium can also include a communications or transmission medium, such as, a bus or a communication link, either optical, wired or wireless having program code segments carried thereon as digital or analog data signals. 
   The claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the invention.