Abstract:
A mobile wireless transmit/receive unit (WTRU), components and methods therefor provide continuous communications capability while switching from a wireless connection with a first type of wireless system to a wireless connection with a second type of wireless system. Preferably, the WTRU is configured to switch wireless links from a Universal Mobile Telecommunications System (UMTS) to a wireless local area network (WLAN) or vice versa during a continuous communication session. The invention is preferably implemented by providing an Application Broker for control signaling and a Communications broker for user data flow which may be embodied in an application specific integrated circuit (ASIC).

Description:
CROSS REFERENCE TO RELATED APPLICATION(S)  
       [0001]    This application claims priority from U.S. Provisional Application No. 60/476,322 filed on Jun. 6, 2003, which is incorporated by reference as if fully set forth herein. 
     
    
     
       FIELD OF INVENTION  
         [0002]    This application relates to components and methods for wireless communication in multiple systems, and, in particular, to mobile wireless transmit/receive units (WTRUs) capable of continuous communications while switching from a wireless connection with a first type of wireless system to a wireless connection with a second type of wireless system, such as from a Universal Mobile Telecommunications System (UMTS) to a wireless local area network (WLAN) or vice versa.  
         BACKGROUND OF THE INVENTION  
         [0003]    Wireless communication systems are well known in the art. Generally, such systems comprise communication stations which transmit and receive wireless communication signals between each other. For network systems such as mobile cellular systems, there are typically two types of communication stations, namely, base stations which provide access to the network infrastructure and wireless transmit/receive units (WTRUs) which conduct wireless communications with the base stations.  
           [0004]    There is a growing dependence upon wireless communications in the home, office, and when traveling. It is not uncommon for a user to have several different WTRUs such as different home, office, and mobile wireless telephones. Accordingly, there is a need to replace the use of multiple WTRUs with a single WTRU which can be used in the home, office and when traveling.  
           [0005]    In many commercial networks, a network of base stations is provided wherein each base station is capable of conducting multiple concurrent wireless communications with appropriately configured WTRUs. In order to provide global connectivity for wireless systems, standards have been developed and are being implemented. One current standard in widespread use is known as Global System for Mobile Telecommunications (GSM). This is considered as a so-called Second Generation mobile radio system standard (2G) and was followed by its revision (2.5G). GPRS and EDGE are examples of 2.5G technologies that offer relatively high speed data service on top of (2G) GSM networks. Each one of these standards sought to improve upon the prior standard with additional features and enhancements. In January 1998, the European Telecommunications Standard Institute—Special Mobile Group (ETSI SMG) agreed on a radio access scheme for Third Generation Radio Systems called Universal Mobile Telecommunications Systems (UMTS). To further implement the UMTS standard, the Third Generation Partnership Project (3GPP) was formed in December 1998. 3GPP continues to work on a common third generational mobile radio standard.  
           [0006]    A typical UMTS system architecture in accordance with current 3GPP specifications is depicted in FIG. 1 a . The UMTS network architecture includes a Core Network (CN) interconnected with a UMTS Terrestrial Radio Access Network (UTRAN) via an interface known as Iu which is defined in detail in the current publicly available 3GPP specification documents.  
           [0007]    The UTRAN is configured to provide wireless telecommunication services to users through WTRUs, called User Equipments (UEs) in 3GPP, via a radio interface known as Uu. The UTRAN has base stations, known as Node Bs in 3GPP, which collectively provide for the geographic coverage for wireless communications with UEs. In the UTRAN, groups of one or more Node Bs are connected to a Radio Network Controller (RNC) via an interface known as Iub in 3GPP. The UTRAN may have several groups of Node Bs connected to different RNCs, two are shown in the example depicted in FIG. 1 a . Where more than one RNC is provided in a UTRAN, inter-RNC communication is performed via an Iur interface.  
           [0008]    A UE will generally have a Home UMTS Network (HN) with which it is registered and through which billing and other functions are processed. By standardizing the Uu interface, UEs are able to communicate via different UMTS networks that, for example, serve different geographic areas. In such case the other network is generally referred to as a Foreign Network (FN).  
           [0009]    Under current 3GPP specifications, the Core Network of a UE&#39;s HN serves to coordinate and process the functions of Authentication, Authorization and Accounting (AAA functions). When a UE travels beyond its Home UMTS Network, the HN&#39;s Core Network facilitates the UE&#39;s use of a Foreign Network by being able to coordinate the AAA functions so that the FN will permit the UE to conduct communications. To assist in implementing this activity, the Core Network includes a Home Location Register (HLR) which tracks the UEs for which it is the HN and a Visitor Location Register (VLR). A Home Service Server (HSS) is provided in conjunction with the HLR to process the AAA functions.  
           [0010]    Under current 3GPP specifications, the Core Network is configured with connectivity to external systems such as Public Land Mobile Networks (PLMN), Public Switch Telephone Networks (PSTN), Integrated Services Digital Network (ISDN) and other Real Time (RT) services via an RT service interface. A Core Network also supports Non-Real Time services with the Internet. External connectivity of the Core Network to other systems enables users using UEs to communicate via their Home UMTS Network beyond the area served by the HN&#39;s UTRAN. Visiting UEs can likewise communicate via a visited UMTS Network, beyond the area served by the visited UMTS&#39;s UTRAN.  
           [0011]    Under current 3GPP specifications, the Core Network provides RT service external connectivity via a Gateway Mobile Switching Center (GMSC). The Core Network provides NRT service, known as General Packet Radio Service (GPRS), external connectivity via a Gateway GPRS Support Node (GGSN). In this context, a particular NRT service may actually appear to a user to be a real time communication due to the communication speed and associated buffering of the TDD data packets forming the communication. One example of this is voice communication via the Internet which can appear to the user as a normal telephone call conducted by a switching network, but is actually being conducted using an Internet Protocol (IP) connection which provides Packet data Service.  
           [0012]    A standard interface known as GI is generally used between a CN&#39;s GGSN and the Internet. The GI interface can be used with Mobile Internet Protocols, such as Mobile IP v4 or Mobile IP v6 as specified by the Internet Engineering Task Force (IETF).  
           [0013]    Under current 3GPP specifications, to provide support for both RT and NRT services from external sources for radio linked UEs in a 3GPP system, the UTRAN must properly interface with the CN which is the function of the Iu interface. To do this, the Core Network includes a Mobile Switching Centre (MSC) that is coupled to the GMSC and a Serving GPRS Support Node (SGSN) that is coupled to the GGSN. Both are coupled with the HRL and the MSC is usually combined with the Visitor Location Register (VLR).  
           [0014]    The Iu interface is divided between an interface for Circuit Switched communications (Iu-CS) and an interface for packet data via Packet Switched communications (Iu-PS). The MSC is connected to the RNCs of the UTRAN via the Iu-CS interface. The Serving GPRS Support Node (SGSN) is coupled to the UTRAN&#39;s RNCs via the Iu-PS interface for Packet Data Services.  
           [0015]    The HLR/HSS is typically interfaced with the CS side of the Core Network, MSC and GMSC via an interface known as Gr which supports AAA functions through a Mobile Application Part (MAP) Protocol. The SGSN and the GGSN of the CN are connected using interfaces known as Gn and Gp.  
           [0016]    Another type of wireless system, called a wireless local area network (WLAN), can be configured to conduct wireless communications with WTRUs equipped with WLAN modems. Currently, WLAN modems are being integrated into many traditional communicating and computing devices by manufactures. For example, cellular phones, personal digital assistants, and laptop computers are being built with one or more WLAN modems. Accordingly, there is an increasing need to facilitate communications among such WTRUs with WLAN modems as well as with different types of networks.  
           [0017]    A popular wireless local area network environment with one or more WLAN Access Points (APs), i.e., base stations, is built according to the IEEE 802.11b standard. The wireless service areas for such WLANs may be restricted to specified well defined geographic areas known as “hot spots”. Such wireless communication systems are advantageously deployed in areas such as airports, coffee shops, and hotels. Access to these networks usually requires user authentication procedures. Protocols for such systems are not yet fully standardized in the WLAN technology area, since the IEEE 802 family of standards is evolving. However, as noted above, the CN of UMTS networks are designed for facilitating communication with other networks such as WLANs.  
           [0018]    In lieu of using a different WTRU in each different environment, WTRUs can be provided with both UMTS and WLAN capabilities, such as pocket PCs with separate UMTS and WLAN PCMCIA card adapters. Separate card components enable a user to use different types of networks via a single device, but does not provide a WTRU capable of switching from one type of network to another without a loss of connectivity. For example, a mobile WTRU communicating with or seeking to communicate with a target WTRU may travel into areas of poor signal quality where the communications with a particular type of network that serves the target WTRU becomes sporadic or nonexistent. In such cases, it would also be desirable if the WTRU can not only roam for within the same type of network, but also switch to a different type of network which maintaining a communication session on an ongoing basis.  
         SUMMARY  
         [0019]    A mobile wireless transmit/receive unit (WTRU), components and methods therefor provide continuous communications capability while switching from a wireless connection with a first type of wireless system to a wireless connection with a second type of wireless system.  
           [0020]    Preferably, the WTRU is configured to switch wireless links from a Universal Mobile Telecommunications System (UMTS) to a wireless local area network (WLAN) or vice versa during a continuous communication session. The invention is preferably implemented by providing a n Application Broker for control signaling and a Communications broker for user data flow which may be embodied in an application specific integrated circuit (ASIC).  
           [0021]    A preferred WTRU in accordance with the invention includes a protocol engine having at least two wireless communication interfaces, each configured for wireless linking with a different type of wireless network. Each communication interface is preferably configured to pass control signals and user communication data to a common application processing component. An application broker is provided that is configured to monitor control signaling between the lower layer protocol engine and the upper layer application processing component. A communications broker is provided that has a data buffer and defines a switchable data path for user data between the upper layer application processing component and a selected one of the wireless interfaces. Preferably, the application broker is associated with the communications broker to control data buffering and data path switching by the communications broker such that data flowing to a first wireless interface of the protocol engine during a communication session is buffered while a wireless link is established with a different second wireless interface of the protocol engine for the communication session and the communication broker data path is switched to the second wireless interface and the buffered data is released therethrough after a wireless link is established for the communication session via the second wireless interface.  
           [0022]    In one embodiment, the communication broker data path is configured to transport packet switched data and a data path is defined for circuit switch data between the upper layer application processing component and a UMTS wireless interface. However, this is not a limiting criteria.  
           [0023]    Preferably, the application broker includes a link monitor and is configured to trigger the initiation of a wireless link through a different wireless interface based upon monitored link data meeting predetermined criteria. The application broker can also include an Application Session Manager configured to controls the signaling during the establishment of a wireless link through a different wireless interface and an inter-working unit configured to maintain and convert context information for transmission during the establishment of a wireless link through a different wireless interface. Additionally, the application broker can include a Subscriber Identity Module (SIM) reader configured to read a SIM containing the user&#39;s identity.  
           [0024]    A preferred wireless link handover method is provided for a wireless transmit/receive unit (WTRU) for switching a wireless link from a first to a second type of wireless network during a communication session wherein the WTRU has a protocol engine having first and second wireless communication interface configured for wireless linking with the first and second types of wireless networks, respectively, each communication interface configured to pass control signals and user communication data to a common application processing component. A data buffer and a switchable data path for user data between the upper layer application processing component and a selected one of the wireless interfaces are provided. Control signaling is monitored between the lower layer protocol engine and the upper layer application processing component. The data buffer and data path switching are controlled such that data flowing to the first wireless interface of the protocol engine during the communication session is buffered while a wireless link is established with the second wireless interface of the protocol engine for the communication session and the data path is switched to the second wireless interface and the buffered data is released therethrough after a wireless link is established for the communication session via the second wireless interface.  
           [0025]    Other objects and advantages of the present invention will be apparent to persons skilled in the art from the following description and accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]    [0026]FIG. 1 a  is a schematic diagram of a typical UMTS system in accordance with current 3GPP specifications.  
         [0027]    [0027]FIG. 1 b  illustrates an example of a mobile WTRU operating in different networks as it travels from a home WLAN to an office LAN while maintaining a continuous communication in accordance with the teachings of the present invention.  
         [0028]    [0028]FIG. 2 a  is a block diagram of a multi-network enabled WTRU in accordance with the teachings of the present invention.  
         [0029]    [0029]FIG. 2 b  is an illustration of a multi-network interface of a multi-network enabled WTRU in accordance with the teachings of the present invention.  
         [0030]    [0030]FIG. 2 c  is a process diagram illustrating the switching of a communication session from a wireless connection via a WLAN to a wireless connection via a UMTS without loss of connectivity in accordance with the teachings of the present invention.  
         [0031]    [0031]FIG. 3 is an illustration of a multi-network operating environment for a multi-network enabled WTRU in accordance with the teachings of the present invention.  
         [0032]    [0032]FIG. 4 a  is a layout diagram of a UMTS device architecture design configured to interface with a computing device, such as via a standard PCMCIA/HBA interface,  
         [0033]    [0033]FIG. 4 b  is a layout diagram of dual UMTS/WLAN network device architecture design configured to interface with a computing device, such as via a standard PCMCIA/HBA interface, in accordance with the teachings of the present invention.  
         [0034]    [0034]FIG. 5 a  is a block diagram of a preferred example of functionality details of an Application broker component for a WTRU in accordance with the teachings of the present invention.  
         [0035]    [0035]FIG. 5 b  is a block diagram of a preferred example of functionality details of a Communication broker component for a WTRU in accordance with the teachings of the present invention.  
         [0036]    [0036]FIG. 6 a  is a protocol stack diagram illustrating preferred locations of the operation of the inventive components in the UE, UTRAN and SGSN in a 3GPP context.  
         [0037]    [0037]FIG. 6 b  is a protocol stack diagram illustrating preferred locations of the operation of the inventive components in a WLAN context.  
         [0038]    [0038]FIG. 7 is a diagrammatic illustration of the location of the inventive components for operation with a WIN CE context. 
     
    
       [0039]    [0039]                                         TABLE OF ACRONYMS                                2G   Second Generation       2.5G   Second Generation Revision       3GPP   Third Generation Partnership Project       AAA   Authentication, Authorization and Accounting       AAL2   ATM Adaptation Layer Type 2       AAL5   ATM Adaptation Layer Type 5       AMR   A type of voice data compression       AP   Access Point (base station in WLAN)       APP   Applications broker       AS   Access Stratum       ASIC   Application Specific Integrated Circuit       ATM   Asynchronous Transfer Mode       CDMA   Code Division Multiple Access       CN   Core Network       CODECs   Coder/Decoders       COM   Communications broker       CP   Control Plane       CS   Circuit Switched       ETSI   European Telecommunications Standard Institute       ETSI SMG   ETSI - Special Mobile Group       FA   Forwarding Address       FN   Foreign Network       G.729   A type of voice data compression       GGSN   Gateway GPRS Support Node       GMM   GPRS Mobility Management       GMSC   Gateway Mobile Switching Center       GPRS   General Packet Radio Service       GSM   Global System for Mobile Telecommunications       GTP   GPRS Tunneling Protocol       GW   Gateway       H.323/SIP   H.323 Format for a Session Initiated Protocol       HLR   Home Location Register       HN   Home Network       HSS   Home Service Server       IETF   Internet Engineering Task Force       IP   Internet Protocol       ISDN   Integrated Services Digital Network       ISP   Internet Service Provider       Iu-CS   Iu sub Interface for Circuit Switched service       Iu-PS   Iu sub Interface for Packet Switched service       IWU   Inter Working Unit       L1C   Level 1 Control       LLC   Logical Link Control (WLAN)       M3UA   Message Transfer Part Level 3 SCCP SS7 Adaptation           Layer       MAC   Medium Access Control       MAP   Mobile Application Part       MSC   Mobile Switching Centre       NAS   Non Access Stratum       Node B   Base station in UMTS       NRT   Non-Real Time       PCM   Pulse Code Modulation       PCMCIA   PC Memory Card International Association       PCMCIA/HBA   PC Memory Card International Association Host Bus           Adapter       PDCP   Packet Data Convergence Protocol       PLMN   Public Land Mobile Network       PPP   Point-to-Point Protocol       PS   Packet Switched       PSTN   Public Switch Telephone Network       RANAP   Radio Access Network Application Part       RAN IP   Radio Access Network Internet Protocol       RIP GW   RAN IP Gateway       RLAN   Radio Local Area Network       RLC   Radio Link Control       RNC   Radio Network Controller       RRC   Radio Resource Control       RT   Real Time       SCCP/MTP   Signaling Connection Control Part, Message Transfer           Part       SGSN   Serving GPRS Support Node       SCTP   Stream Control Transmission Protocol       SIM   Subscriber Identity Module       SM   Session Management       SMS   Short Message Service       SS7   Signaling System 7       SSCF   Service Specific Coordination Function       SSCOP   Service Specific Connection Oriented Protocol       TCP   Transmission Control Protocol       TDD   Time Division Duplex       UDP/IP   User Data Protocol for the Internet Protocol       UE   User Equipment (WTRU for UMTS)       UICC   UMTS Integrated Circuit Card       UMTS   Universal Mobile Telecommunications System       UP   User Plane       UTRAN   UMTS Terrestrial Radio Access Network       WIN CE   Windows CE       WLAN   Wireless Local Area Network       WTRU   Wireless Transmit Receive Unit       VLR   Visitor Location Register                    
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]    The present invention is described with reference to the drawing figures wherein like numerals represent like elements throughout.  
         [0041]    The term base station as used herein includes, but is not limited to, a base station, Node B, site controller, Access Point (AP) or other interfacing device in a wireless environment that provides WTRUs with wireless access to a network with which the base station is associated.  
         [0042]    The term WTRU as used herein includes, but is not limited to, a user equipment (UE), mobile station, fixed or mobile subscriber unit, pager, or any other type of device capable of operating in a wireless environment. WTRUs include personal communication devices, such as phones, video phones, and Internet ready phones that have network connections. In addition, WTRUs include portable personal computing devices, such as PDAs and notebook computers with wireless modems that have similar network capabilities. WTRUs that are portable or can otherwise change location are referred to as mobile units.  
         [0043]    The present invention provides for continuous communication sessions via differing types of wireless radio access networks having one or more networked base stations through which wireless access service is provided for WTRUs. The invention is particularly useful when used in conjunction with mobile units, i.e., mobile WTRUs, as they enter and/or travel through the respective areas of geographic coverage provided by the respective base stations of different types of networks. For example, FIG. 1 b  illustrates a mobile WTRU  10  at three different locations  10   a ,  10   b ,  10   c . At location  10   a , the WTRU conducts wireless communication with an AP  12  of a home WLAN. At location  10   b , the WTRU conducts wireless communication with a Node B  13  of UMTS while traveling between the home WLAN and an office WLAN. At location  10   c , the WTRU conducts wireless communication with an AP  15  of an office WLAN. Network connectivity is provided by connections of a CN  14  of the UMTS with the home and office WLANs. The WTRU  10  of the present invention, takes advantage of this network connectivity to maintain an ongoing communication session initiated at the home WLAN  10   a  and continued at the office WLAN  10   c  by switching between WLAN and UMTS wireless communications while in transit  10   c.    
         [0044]    In accordance with the invention, WTRUs are configured for at least two different network modes of operation, preferably, by being equipped with devices providing UMTS UE functionality and wireless local area network (WLAN) WTRU functionality, such as 802.11(b) (WiFi) or Bluetooth compliant functionality. However, the proposed invention is applicable to provide continuity of communication sessions for any other type of wireless network system that interconnects with other types of networks.  
         [0045]    Referring to FIG. 2, a WTRU  10  is provided with a protocol engine  20  having at least two wireless communication interfaces  22 ,  24 , of different types. Each communication interface  22 , 24  is configured to pass control and user communication data to an application processing component  26  representing conventional upper layers of communication systems. Preferably, one of the wireless communication interfaces  22 ,  24  is configured for UMTS wireless communications and the other is configured for 802.11 WLAN communications.  
         [0046]    The invention provides for the interposition of an Application broker (APP)  30  and a Communications broker (COM)  32  between the wireless interfaces  22 ,  24  and the upper layer application processing component  26 . The APP and COM components  30 ,  32  process the control and user data preferably as a type of “middleware” that helps in inter-working different technologies by abstracting the underlying base system to enhance performance capabilities. The Application broker  30  and Communications broker  32  provide a two-tier middleware architecture that does not require a change to conventional protocol architectures for the respective wireless networks, easily integrate the different network technologies and provide seamless service to the user.  
         [0047]    The APP  30  is configured to monitor the control signaling between the lower layer protocol engine  20  and the upper layer application processing component  26 . All user communication data flows through the COM  32  which serves as a switch for the upper layer application processing component  26  to direct such data to the appropriate wireless interface  22 ,  24  within the lower layer protocol engine  20 .  
         [0048]    The middleware components  30 ,  32  can be implemented in the WTRU without corresponding network components. The APP  30  and the COM  32  can operate in such a standalone WTRU scenario to maintain a wireless communication session while switching networks. As such, dual mode operation is supported in the WTRU without overall network support and no “context transfer” or end to end “session awareness” is required.  
         [0049]    For example, if the WTRU  10  is conducting a UMTS wireless communication via interface  22  and travels into a WLAN service area the communication session is preferably switched to WLAN wireless communication via interface  24  in a WTRU standalone mode as follows. The protocol engine  20  provides link status information which is received and evaluated by the APP  30  and a determination is made to switch to WLAN wireless communications. This decision can be based on Quality of Service (QoS) of the existing UMTS or other factors such as disclosed in U.S. patent application Ser. No. 10/667,633 owned by the assignee of the present invention. After the APP  30  determines the ongoing UMTS communication session should be handed over to a WLAN, the APP  30  signals the COM  32  to prepare for handoff and the COM  32  begins to buffer all communication data being generated by the upper layer application processing component  26  for wireless transmission. Accordingly, the processing component  26  continues its generation of user data for the communication session without interruption. The APP  30  communications to the upper layer application processing component  26  that handoff is in progress so that it can anticipate a delay in receiving wireless data until the handoff is complete. The APP  30  then directs the protocol engine  20  to establish a wireless WLAN connection via interface  24  to which the UMTS communication session is to be handed.  
         [0050]    The protocol engine  20  signals the APP  30  when the WLAN connection is established. The App  30  then signals handoff completion to the COM  32  which in turn switches the direction of the user communication data from the UMTS interface  22  to the WLAN interface  24  and releases the buffered data to the WLAN interface to update and continue the communication session. The APP also signals handoff completion to the upper layer application processing component  26  so the bi-direction user data for the communication session continues traveling via the COM  32  and WLAN interface  24 . Finally, the APP  30  signals the protocol engine to have the UMTS interface release the UMTS connection.  
         [0051]    For enhanced operation, corresponding APP and COM components can be provided in the networks with which the WTRU  10  is communicating. FIG. 2 b  provides a schematic diagram of the layout of the various components. Network system interfacing between UMTS systems and WLAN systems are typically based on Packet Switched (PS) data flows such as using an Internet Protocol (IP). FIG. 2 b  illustrates a WTRU configured to permit network handoff for packet switched IP sessions. CS voice signal data can pass through the APP from the UMTS interface, but voice communications are possible to implement in both a WLAN and a UMTS using a voice over IP protocol where voice data is processed in packets.  
         [0052]    As reflected in FIG. 2 b , the APP  30  of WTRU  10  brokers the signaling with the wireless interfaces  22 ,  24  between higher layers and the COM  22 . The WTRU  10  is configured to pass PS data to and from the wireless interfaces  22 ,  24  through the COM  32 . Preferably, the UMTS and WLAN systems with which the WTRU communicates have UTRANs and APs, respectively, configured with corresponding Communication Brokers implemented above their respective physical layer air interfaces as illustrated in FIG. 2 b . A corresponding Application broker is preferably provided in an IP node of the network systems. The network side APPs and COMs provide network support for inter-network handover.  
         [0053]    In the context of the multi-network system illustrated in FIG. 2 b , an example of the WTRU  10  switching from a WLAN connection to a UMTS connection during a communication session with network support is illustrated in FIG. 2 c . During an existing WLAN session, control and user data pass through the WTRU&#39;s APP  30  and COM  32 , respectively, and over the WTRU&#39;s communication link via an AP of the WLAN. The user data passing through the COM of the AP and the control data passing to a network APP. When the communications link reports data to the WTRU APP  30  based on which the APP determines the link should be switched to a UMTS, the WTRU APP  30  signals the WTRU COM  32  to begin buffering up link user communication data and also signals the network APP which in turn signals the AP COM to begin buffering down link user communication data. The WTRU COM  32  also preferably stores contest information related to the user data, notes the last down link packet received from the AP and identifies the last received down link packet to the WTRU APP  30 . The WTRU APP  30  then directs the WTRU interface to set up a UMTS link. Provided a UMTS link is available, it is set up and the WTRU link via a UMTS UTRAN is confirmed to the WTRU APP  30 . The WTRU APP  30  then confirms this to the WTRU COM  32  and preferably signals to the network APP via the UMTS connection context information including AAA and QoS information. The WTRU COM  32  also preferably signals context in formation relate to the user communication data to the UTRAN COM. The WTRU APP  30  also signals the network APP the identity of the last received downlink packet with a request to resume communications which in turn is signaled by the network APP to the AP COM. The AP COM releases the buffered downlink data to the UTRAN COM preferably starting with the next successive packet following the packet identified as last received downlink packet. The buffered data is then exchanged via the UMTS connection through the WTRU COM  32  and the UTRAN COMM. The communication then continues as normal via the UMTS connection.  
         [0054]    With reference to FIG. 3, a block diagram of the WTRU  10  in the context of a multi-network environment which includes internet connectivity. The WLAN network includes an Access Point (AP) connected to a WLAN Gateway that has an associated WLAN AAA tracking component. The UMTS includes a UTRAN and AAA, SGSN and GGSN Core Network components. The WLAN interfaces with the internet through the WLAN Gateway and the UMTS interfaces with the internet via the GGSN component of the UMTS CN. Preferably, there is an AAA interface between the WLAN AAA and UMTS AAA components.  
         [0055]    In the context of the multi-network system illustrated in FIG. 3, an example of the WTRU  10  switching from a WLAN connection to a UMTS connection during a communication session with an internet connected device  40  proceeds as follows. When the communications link status indicates to the WTRU APP  30  that the link should be switched to a WLAN link, the WTRU APP  30  signals the WTRU COM  32  to begin buffering up link user communication data. The WTRU COM  32  also preferably stores contest information related to the user data, notes the last down link packet received from the UTRAN and identifies the last received down link packet to the WTRU APP  30 . The WTRU APP  30  then receives AAA context information from the UMTS AAA control and directs the WTRU interface to set up a UMTS link. A WLAN link is set up and the WTRU link via a WLAN UTRAN is confirmed to the WTRU APP  30 . The WTRU APP  30  then confirms establishment of the WLAN link to the WTRU COM  32  and preferably also appropriately converts the AAA context data and signals it to the WLAN AAA component. The WTRU COM  32  then releases the buffered uplink data to the internet connected device  40 . The communication then continues as normal between the WTRU  10  and the internet connected device  40  via the WLAN connection.  
         [0056]    Referring to FIGS. 4 a  and  4   b , there is shown an implementation of the APP and COM components device configured to interface with a computing device, such as via a standard PCMCIA/HBA interface. FIG. 4 a  illustrates a layout diagram of a UMTS device architecture design configured to interface with a computing device, such as via a standard PCMCLA/HBA interface. Non Access Stratum (NAS), Access Stratum (AS), Layer 1 Control (L1C) and physical layer (Layer 1) components are illustrated with data paths of control signals and user data, including both packet switched (PS) and circuit switched (CS) data paths. The NAS layer is coupled to a standard computer interface for coupling via a standard PCMCIA/HBA interface connector.  
         [0057]    [0057]FIG. 4 b  illustrates a modification of the device of FIG. 4 a  to provide a dual UMTS/WLAN network device architecture in accordance with the teachings of the present invention. An Application broker  30  is disposed in the control signal path between the NAS layer and the computer interface. A Communications broker  32  that is coupled with the APP  30  is disposed in the PS data path between the NAS layer and the computer interface. WLAN interface components are provided preferably including an 802.11 compliant physical layer, Layer 1 Control components and 802.11 compliant Medium Access Control (MAC) and Logical Link Control (LLC) components. The Medium Access Control (MAC) and Logical Link Control (LLC) components have a control signal path coupled with the APP  30  and a PS data path coupled with the COM  32 .  
         [0058]    Preferred detailed configuration layouts of the APP  30  and COM  32  components are illustrated in FIGS. 5 a  and  5   b , respectively. The APP  30  preferably includes a communication module coupled with a central processing unit. The communication module has external connections for the couplings with the higher layer processing (application), the WLAN interface via LLC control (LLC), the UMTS interface via NAS level control (NAS) and the COM  32  (COM). An L1 connection is also directly provided to the physical layer to assist in the monitoring of link status.  
         [0059]    The APP  30  preferably includes Link Monitor, Application Session Manager, Inter-Working Unit and Subscriber Identity Module (SIM) Reader components associated with its central processing unit. The Link Monitor component is configured to monitor link status and to trigger hand off from one type of wireless network link to the other if selected criteria are net. The Application Session Manager is configured to controls the signaling during handoff. The Inter-Working Unit is configured to maintain and convert AAA, QoS profile and other context information for transmission during handoff. The SIM Reader is configured to read a SIM containing the user&#39;s identity for AAA functioning.  
         [0060]    The COM  32  is preferably configured with a Control component, a Switch/Buffer device and a read/write (R/W) device. The control component is configured to control the switching of the PS-data flow between the UMTS and WLAN interfaces depending upon the type of wireless connection and has a connection coupled with the APP  30  for receiving control signals. The Switch/Buffer and R/W devices are disposed in the PS data path between the two interfaces and the higher layer processing. The Switch/Buffer has a WLAN connection (LLC) and a UMTS connection (PS) and the PS data flow is through one or the other connection as controlled by the Control component. The Switch/Buffer and R/W devices are to interrupt the data flow from the high layer connection (IP Data) and buffer the data received during handover and then release the buffered data once the new network connection is established and the data path is switched by the Control component.  
         [0061]    For completeness, FIGS. 6 a  and  6   b  are provided to illustrate the preferred WTRU and network locations of the APP and COM in UMTS and WLAN protocol stacks respectively. FIG. 6 a  illustrate the APP within the Control Plane (CP) protocol stacks and the COM within the User Plane (UP) protocol stacks of a UMTS network. FIG. 6 b  illustrates the APP and COM locations in WLAN protocol stacks for the WTRU, a WLAN AP and a WLAN gateway configured with a 802.11 compliant wireless interface and a 802.3 intra-WLAN interface.  
         [0062]    The ability to create UMTS and WLAN (standard 802.11) inter-working is the culmination of an evolution path comprising the steps of roaming, handoff, and seamless handoff, ending in the present dual mode WTRU. Network interface strategies are addressed in the 3GPP Technical Report TR 23.934. The present invention addresses the seamless handoff situation providing an architecture that supports seamless handoff with no coupling, or loose coupling, or tight coupling scenarios.  
         [0063]    The new APP and COM components can be extended to integrate any access technology. FIG. 7 is a diagrammatic illustration of the location of these components in a dual wireless interface device (UE+WLAN Engine) such as illustrated in FIG. 4 b  for operation within a WIN CE context.  
         [0064]    Exemplary attributes of the COM broker include ability to abstract the transport mechanism to upper layers. Although described above for PS data, the COM, being on the user plane can be implemented to routes user data in the form of CS and/or PS data depending on the current system to which is attached. From a UMTS point of view the COM component preferably resides on top of PDCP/RLC/MAC/PHY protocols. The COM can be implemented as a generic software component which can be adapted to any access technology.  
         [0065]    Exemplary attributes of the Access Broker (APP) include the ability to abstracts all applications at session and presentation layers. The APP preferably resides on the signaling (control) plane (CP), collects reports of link quality and has the ability to triggering handoff and assists in session re-establishment.  
         [0066]    Preferably, the APP and COM components are implemented on an single integrated circuit, such as an application specific integrated circuit (ASIC) which may also include the UMTS and WLAN interface components. However, portions of the processing components may also be readily implemented on multiple separate integrated circuits.  
         [0067]    WTRU configurations and methods have been described for use with UMTS and WLAN systems. However, the present invention can be implemented for any wireless communications network system where the WTRUs are configured to communicate with multiple types of wireless networks.