Patent Abstract:
A method of and apparatus for handover between a 3GPP based network and a non-3GPP network is disclosed where a policy update to a new gateway is requested. A confirmation of the policy update is sent from the policy and charging rules function (PCRF) to the 3GPP packet data network gateway (PDN GW). The new gateway also confirms the policy update to the currently serving gateway. The tunnel endpoints and radio resources are released between the PDN GW and the evolved Packet Data Gateway (ePDG), thereby freeing the resources previously used by the wireless transmit/receive unit (WTRU). A release acknowledgement is sent from the serving gateway to the PCRF confirming the policy update process is complete. The method may be used for handover between 3GPP and non-3GPP networks and vice versa. The method and apparatus may be practiced over the S 2   b  or S 2   c  interfaces.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/945,610 filed on Jun. 22, 2007 and U.S. Provisional Application No. 60/946,162 filed on Jun. 26, 2007, which are incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    The application relates to wireless communications. More particularly, the application relates to resource management when moving between different wireless communication architectures. 
       BACKGROUND 
       [0003]    In mobile communication systems, the nature of mobile devices creates situations where as a wireless transmit/receive unit (WTRU) moves through an area, the WTRU may encounter multiple gateways through which it could connect. These multiple gateways may use different communication architectures to connect devices and to Internet protocol (IP) access. 
         [0004]    Some gateways may be under the control of a service to which the WTRU user subscribes. Other gateways may belong to systems that are not aware of the user but may still allow the user&#39;s WTRU to establish a connection. 
         [0005]    As the user moves throughout the coverage areas of these gateways, it may be better for the WTRU to switch from a current communication architecture to another architecture, such as a trusted network, or a network that may be able to take advantage of more sophisticated capabilities of the WTRU. When this occurs, a handover takes place to move the access from the original network architecture to the newly detected architecture. Likewise, when a trusted network architecture&#39;s signal becomes weak, the WTRU may decide to handover to a different network architecture. 
         [0006]    In prior handoff methodologies, the WTRU could establish connectivity with the new network architecture and abruptly sever its connection with the original network. It would be beneficial if the original network connection could be terminated in an orderly fashion when handover between network architectures occurs. 
         [0007]    The network architecture showing the relationship between a third generation partnership project (3GPP) architecture and a non-3GPP architecture is depicted in  FIG. 1 . A network architecture  100  includes a 3GPP and non-3GPP system architecture, divided by a dashed line  101 . Above the line  101  is 3GPP compliant architecture and below the dashed line  101  connections is a non-3GPP architecture. WTRU  103  may gain access to the 3GPP architecture through connection S 2   a    105 , S 2   b    107 , or S 2   c    109 , depending on the architecture to which the WTRU  103  is connected and the relation of that architecture to the 3GPP network. If the non-3GPP architecture is a trusted non-3GPP IP connection  111 , the connection to the packet data network gateway  113  is made directly through S 2   a    105 . S 2   a    105  provides the user plane with related control and mobility support between trusted non 3GPP IP access and the packet data network (PDN) Gateway (GW)  113 . 
         [0008]    When the non-3GPP architecture is untrusted  115 , the connection is made through an evolved Packet Data Gateway (ePDG)  117 . The connection between the ePDG  117  and the PDN GW  113  is made through an S 2   b    109  connection. S 2   b    109  provides the user plane with related control and mobility support between evolved packet data gateway (ePDG  117 ) and the PDN GW  113 . 
         [0009]    Connection between the WTRU  103  and the PDN GW  113 , while the WTRU  103  is connected to either a trusted or untrusted non-3GPP or 3GPP, may be provided through S 2   c    107 . S 2   c    107  provides the user plane with related control and mobility support between a wireless transmit/receive unit (WTRU)  103  and the PDN GW  113 . This reference point is implemented over trusted and/or untrusted non-3GPP access and/or 3GPP access. 
         [0010]    An S 5  connection  119  exists between the PDN GW  113  and a serving gateway  121  in the 3GPP system. S 5   119  provides user plane tunneling and tunnel management between Serving GW and PDN GW. It is used for Serving GW relocation due to mobility and in case the Serving GW needs to connect to a non-collocated PDN GW for the required PDN connectivity. 
         [0011]    An S 6   a  interface  123  is defined between mobility management entity (MME)  125  and home subscriber server (HSS)  127  for authentication and authorization. 
         [0012]    The point defined by S 6   c    129  is the reference point between PDN GW  113  in a home public land mobile network (HPLMN) and a 3GPP authentication, authorization and accounting (AAA) server  131  for mobility related authentication if needed. This reference point may also be used to retrieve and request storage of mobility parameters. 
         [0013]    Reference point S 6   d  (not shown) is between Serving Gateway in a visited public land mobile network (VPLMN) and a 3GPP AAA Proxy for mobility related authentication if needed. This reference point may also be used to retrieve and request storage of mobility parameters. 
         [0014]    Connection S 7   133  provides transfer of quality of service (QoS) policy and charging rules from policy and charging rules function (PCRF)  135  to policy and charging enforcement point (PCEF) (not shown). 
         [0015]    SGi  117  is the reference point between the PDN Gateway  113  and the packet data network  139 . The packet data network  139  may be an operator external public or private packet data network or an intra operator packet data network, e.g. for provision of IP multimedia subsystem (IMS) services. This reference point supports any 3GPP and non-3GPP access systems. 
         [0016]    Wa*  141  connects the untrusted non-3GPP IP access with the 3GPP AAA server/proxy  131  and transports access authentication, authorization and charging-related information in a secure manner. 
         [0017]    Ta*  143  connects the trusted non-3GPP IP Access  111  with the 3GPP AAA server/proxy  131  and transports access authentication, authorization, mobility parameters and charging-related information in a secure manner. 
         [0018]    The Wm*  145  reference point is located between 3GPP AAA Server/Proxy  131  and ePDG  117  and is used for AAA signaling, (transport of mobility parameters, tunnel authentication and authorization data). 
         [0019]    Wn*  147  is the reference point between the untrusted Non-3GPP IP Access  115  and the ePDG  117 . Traffic on this interface for a initiated tunnel has to be forced towards ePDG  117 . 
         [0020]    Wx*  149  is the reference point is located between 3GPP AAA Server  131  and HSS  127  and is used for transport of authentication data. 
         [0021]    A diagram illustrating the handover process between untrusted non-3GPP IP access using PMIPv6 to an E-UTRAN 3GPP network is depicted in  FIG. 2 . The WTRU  201  is initially connected to the untrusted non-3GPP access. There is an IPsec tunnel  203  between the WTRU  201  and the ePDG  205  and a PMIPv6 tunnel  207  between the ePDG and the PDN GW  209 . As the WTRU  201  moves, it may switch from the untrusted non-3GPP IP access to a 3GPP architecture such as E-UTRAN. The WTRU  201  attaches to the E-UTRAN network  211 . Next, the WTRU  201  performs access authorization with the mobility management entity (MME)  213 . The MME  213  contacts the home subscriber server (HSS)  215  for authentication of the WTRU  201 . As part of the authentication procedure, the packet data network gateway (PDN GW)  209  that will be used is conveyed to the MME  213 . The MME  213  performs a location update procedure and subscriber data retrieval  214  from the HSS  215 . After the MME  213  authenticates the WTRU  201 , it sends a create default bearer request message  217  to the serving gateway (GW)  219 . In the message  217 , the MME  213  includes the WTRU&#39;s  201  identifier (NAI) and the PDN GW  209  that will be used. The serving GW  219  sends a proxy binding update (BU) message  221  to the PDN GW  209  to setup a default bearer for the WTRU  201 . The proxy BU  221  includes the WTRU&#39;s  201  identifier and a request for an IP address from the PDN GW  209 . The PDN GW  209  processes the proxy BU message  221  from the serving GW  219 , updates the binding cache entry for the WTRU  201  and responds with a proxy binding acknowledgement  223 . In the proxy binding acknowledgement (Ack)  223 , the PDN GW  209  replies with the same IP address or prefix that was assigned to the WTRU  201  earlier. At that point a PMIPv6 tunnel  225  exists between the PDN GW  209  and the serving GW  219 . The serving GW  219  responds to the MME  213  with the create default bearer response message  217 . In this message  217 , the serving GW  219  includes the IP address of the WTRU  201 . An S1_U default bearer establishment procedure  227  is performed. This procedure includes a radio bearer setup  228 . At the end of the handover procedure  200 , there is a default bearer for the WTRU  201  that consists of E-UTRAN radio bearer  227 , S1 bearer between the e Node B and the serving GW  219  and a PMIPv6 tunnel  229  between the serving GW  219  and the PDN GW  209 . 
         [0022]      FIGS. 3A and 3B  are an illustration of a handover procedure over interface S 2   c  of  FIG. 1  from non-3GPP IP Access to 3GPP access. The session starts in untrusted non-3GPP access  301  using DSMIPv6 over the S 2   c  interface. The session hands over to 3GPP access, for example, E-UTRAN  303 . The WTRU  305  uses an untrusted non-3GPP access system  301 . It has an IPsec/IKEv2 session with the ePDG  307  and a DSMIPv6 session with the PDN GW  309 . The WTRU  305  discovers the 3GPP access system  303  and decides to handover from the currently used trusted non-3GPP  301  access system to the discovered 3GPP access system  302 . The WTRU  305  sends an attach request  313  which is routed by 3GPP access system  303  to an MME  311  instance in the evolved packet core (EPC) which is not shown. The MME  311  contacts the HSS/3GPP authorization and authentication (AAA)  315  and authenticates the WTRU  305 . As part of the authentication procedure, the IP address of the PDN GW  309  that will be used for 3GPP access is conveyed to the MME  311 . After successful authentication, the MME  311  performs a location update procedure with HSS  315 . The MME  311  selects a serving GW  317  and sends a create default bearer request message  319  to the selected PDN GW  309 . The serving GW  317  may initiate the PMIPv6 registration procedure towards the PDN GW  309  by sending a Proxy Binding Update  321 , such as when using Internet Engineering Task Force (IETF) based S 5  interface between the PDN GW  309  and the serving GW  317 . If GPRS Tunneling Protocol (GTP) is used for S 5 , the serving GW  307  send a create bearer request message  309  to the PDN GW  309 . In IETF based S 5 , the PDN GW  309  responds with a proxy binding acknowledgement  327  and updates its mobility binding which effectively switches the DSMIPv6 tunnel from the non-3GPP access network to the PMIPv6 tunnel to the serving GW  307 . In the proxy binding acknowledgement  327 , the PDN GW  309  includes the home IP address or prefix that was assigned to the WTRU  305  earlier. For GTP-based S 5 , the PDN GW  309  responds with a create bearer response message  329  to the serving GW  307 . The create bearer response  329  contains the home IP address or prefix that was assigned to the WTRU  305  earlier. The serving GW  317  then returns a create default bearer response message  329  to the MME  311  that includes the IP address of the WTRU  305 . This message  329  also serves as an indication to the MME  311  that the binding was successful. The MME  311  sends an attach accept message  331  to the WTRU  305  through 3GPP access  303 . The 3GPP access system  303  initiates radio bearer setup procedures and the 3GPP access system responds with an Attach Complete Message  331 . The WTRU  305  may send a binding update  321  to the PDN GW  309  to de-register its DSMIPv6 binding  325  that was created with the WTRU  305  was in untrusted non-3GPP IP access  301 . The WTRU  305  may send IKEv2 messages if necessary to tear down its system aspects (SA) with the ePDG  307 . 
         [0023]    A handover process  400  from 3GPP IP Access to untrusted non-3GPP IP access over the S 2   b  interface is shown in  FIG. 4 . The WTRU  401  is connected to the 3GPP network through the serving GW  403  through a PMIPv6 Tunnel  405  to the PDN GW  407  when handover is initiated and the WTRU attaches to the non-3GPP network  411 . Authentication of the WTRU  401  is done by the HSS/AAA  409  on the 3GPP system. IKEv2 authorization and tunnel setup  415  between the WTRU  401  and the ePDG  413 . A proxy binding update message  417  is sent the PDN GW  407 . The proxy binding Acknowledgement message  419  is returned to the ePDG  413 . The IPsec tunnel setup and address configuration is performed  421  and the PMIPv6 tunnel  423  is established between the ePDG  413  and the PDN GW  407 . Non-3GPP IP access is now established through an IPsec Tunnel  425  between the WTRU  401  and the ePDG  413  and a PMIPv6 tunnel  427  between the ePDG  413  and the PDN GW  407 . 
         [0024]    The handover process  500  from 3GPP IP Access to trusted/untrusted non-3GPP IP access over the S 2   c  interface is shown in  FIG. 5 . The WTRU  501  is connected to the 3GPP network through the serving GW  503  through a PMIPv6 Tunnel  505  to the PDN GW  507  when handover is initiated and the WTRU attaches to the non-3GPP network  511 . Authentication of the WTRU  501  is done by the HSS/AAA  509  on the 3GPP system. IKEv2 authorization and tunnel setup  515  between the WTRU  501  and the ePDG  513  when the non-3GPP network is untrusted. Alternatively, the IKEv2 authorization and tunnel setup  516  may occur between the WTRU  501  and the PDN GW  507  when the non-3GPP network is a trusted network. A proxy binding update message  517  is sent the PDN GW  507 . The proxy binding Acknowledgement message  517  is returned to the ePDG  513 . The IPsec tunnel setup and address configuration is performed  521  and the PMIPv6 tunnel  527  is established between the WTRU  501  and the PDN GW  507 . Non-3GPP IP access is now established through an IPsec Tunnel  525  between the WTRU  501  and the ePDG  513  and a PMIPv6 tunnel  527  between the WTRU  501  and the PDN GW  507 . 
       SUMMARY 
       [0025]    A method for and apparatus for handover between a 3GPP based network and a non-3GPP network is disclosed where a policy update to a new gateway is requested. A confirmation of the policy update is sent from the policy and charging rules function (PCRF) to the 3GPP packet data network gateway (PDN GW). The new gateway also confirms the policy update to the 3GPP serving gateway. The tunnel endpoints and radio resources are released between the PDN GW and the evolved Packet Data Gateway (ePDG), thereby freeing the resources previously used by the wireless transmit/receive unit (WTRU). A release acknowledgement is sent from the serving gateway to the PCRF confirming the policy update process is complete. The method may be used for handover between 3GPP and non-3GPP networks and vice versa. The method and apparatus may be practiced over the S 2   b  or S 2   c  interfaces. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0026]    A more detailed understanding of the invention may be had from the following description of a preferred embodiment, given by way of example and to be understood in conjunction with the accompanying drawings wherein: 
           [0027]      FIG. 1  shows a conventional network architecture; 
           [0028]      FIG. 2  is a diagram showing an untrusted non-3GPP IP access with PMIPv6 to E-UTRAN handover in a conventional non-roaming scenario over S 2   b;    
           [0029]      FIGS. 3A and 3B  show an untrusted non-3GPP IP access with PMIPv6 to E-UTRAN handover in a conventional non-roaming scenario over S 2   c;    
           [0030]      FIG. 4  shows an E-UTRAN to untrusted non-3GPP IP access with PMIPv6 handover in a conventional non-roaming scenario over 2Sb; 
           [0031]      FIG. 5  shows proposed enhancements to an E-UTRAN to untrusted non-3GPP IP access handover using S 2   c  in a non-roaming case; 
           [0032]      FIGS. 6A and 6B  show proposed enhancements to an untrusted non-3GPP IP access to E-UTRAN handover using S 2   b  in a non-roaming case; 
           [0033]      FIGS. 7A and 7B  show proposed enhancements to an untrusted non-3GPP IP access to E-UTRAN with PMIPv6 handover in a non-roaming scenario using S 2   c.    
           [0034]      FIGS. 8A and 8B  show proposed enhancements from an E-UTRAN network to an untrusted non-3GPP IP access handover using S 2   b  in a non-roaming case; 
           [0035]      FIGS. 9A and 9B  shows proposed enhancements to an E-UTRAN to untrusted non-3GPP IP access with PMIPv6 handover in a non-roaming scenario using S 2   c.    
           [0036]      FIG. 10  is a block diagram of a wireless transmit/receive unit (WTRU). 
       
    
    
     DETAILED DESCRIPTION  
       [0037]    When referred to hereafter, the terminology “wireless transmit/receive unit (WTRU)” includes but is not limited to a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the terminology “base station” includes but is not limited to a Node-B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment. 
         [0038]    A simplified diagram of a WTRU is shown in  FIG. 10 . The WTRU  103  is comprised of an antenna  1001  for sending and receiving wireless signals. A processor  1003  controls the other components of the WTRU. A memory  1005  stores data, for example instructions that may be executed by the processor  1003 . A transceiver  1007  sends and transmits data through the antenna  1001 . 
         [0039]    A diagram illustrating an enhanced handover process  600  between untrusted non-3GPP IP access using PMIPv6 to an E-UTRAN 3GPP network over the S 2   b  interface is depicted in  FIGS. 6A and 6B . The enhancements are added with respect to the handover as described in  FIG. 2 . The WTRU  201  is initially connected to the untrusted non-3GPP access. There is an IPsec tunnel  203  between the WTRU  201  and the ePDG  205  and a PMIPv6 tunnel  207  between the ePDG and the PDN GW  209 . As the WTRU  201  moves, it may be moved from the untrusted non-3GPP IP access to a 3GPP architecture such as E-UTRAN. The WTRU  201  attaches to the E-UTRAN network  211 . Next, the WTRU  201  performs access authorization with the MME  213 . The MME  213  contacts the HSS  215  for authentication of the WTRU  201 . As part of the authentication procedure, the PDN GW  209  that will be used is conveyed to the MME  213 . The MME  213  performs a location update procedure and subscriber data retrieval  214  from the HSS  215 . After the MME  213  authenticates the WTRU  201 , it sends a create default bearer request message  217  to the serving GW  219 . In the message  217 , the MME  213  includes the WTRU&#39;s  201  NAI and the PDN GW  209  that will be used. The serving GW  219  sends a proxy BU message  221  to the PDN GW  209  to setup a default bearer for the WTRU  201 . The proxy BU  221  includes the WTRU&#39;s  201  identifier and a request for an IP address from the PDN GW  209 . The PDN GW  209  processes the proxy BU message  221  from the serving GW  219 , updates the binding cache entry for the WTRU  201  and responds with a proxy binding acknowledgement  223 . In the proxy binding acknowledgement  223 , the PDN GW  209  replies with the same IP address or prefix that was assigned to the WTRU  201  earlier. At that point a PMIPv6 tunnel  225  exists between the PDN GW  209  and the serving GW  219 . 
         [0040]    A policy update message  601  is sent from the PDN GW  209  to a PCRF  613 . The PCRF  613  sends a policy update confirmation message  603  to the PDN GW  209 . The serving GW  219  responds to the MME  213  with the create default bearer response message  217 . In this message  217 , the serving GW  219  includes the IP address of the WTRU  201 . The PCRF  613  sends a policy information update message  605  to the serving GW  219 . The PDN GW  209  sends a message to the ePDG  205  to release tunnel endpoints and radio resources  607 . The ePDG  205  responds with a release acknowledgement message  609 . An S1_U default bearer establishment procedure  227  is performed including a radio bearer setup  228 . The serving GW  219  sends a policy update confirmation message  611  to the PCRF  613 . At the end of the handover procedure  200 , there is a default bearer for the WTRU  201  that consists of E-UTRAN radio bearer  227 , S1 bearer between the e Node B and the serving GW  219  and a PMIPv6 tunnel  229  between the serving GW  219  and the PDN GW  209 . 
         [0041]      FIGS. 7A and 7B  show an enhanced handover process between untrusted non-3GPP IP access using PMIPv6 to an E-UTRAN 3GPP network over the S 2   c  interface. Enhancements are added to the handover operation described in  FIG. 3 . The session starts in untrusted non-3GPP access  301  using DSMIPv6 over the S 2   c  interface. The session hands over to 3GPP access, for example, E-UTRAN  303 . The WTRU  305  uses an untrusted non-3GPP access system  301 . It has an IPsec/IKEv2 session with the ePDG  307  and a DSMIPv6 session with the PDN GW  309 . The WTRU  305  discovers the 3GPP access system  303  and determines to handover from the currently used trusted non-3GPP  301  access system to the discovered 3GPP access system  303 . The WTRU  305  sends an attach request  313  which is routed by 3GPP access system  303  to an MME  311  instance in the evolved packet core (EPC) which is not shown. The MME  311  contacts the HSS/3GPP AAA  315  and authenticates the WTRU  305 . As part of the authentication procedure, the IP address of the PDN GW  309  that needs to be used for 3GPP access is conveyed to the MME  311 . After successful authentication, the MME  311  performs a location update procedure with HSS  315 . The MME  311  selects a serving GW  317  and sends a create default bearer request message  319  to the selected PDN GW  309 . The serving GW  317  may initiate the PMIPv6 registration procedure towards the PDN GW  309  by sending a Proxy Binding Update  321 , such as when using Internet Engineering Task Force (IETF) based S 5  interface between the PDN GW  309  and the serving GW  317 . If GPRS Tunneling Protocol (GTP) is used for S 5 , the serving GW  317  sends a create bearer request message  319  to the PDN GW  309 . In IETF based S 5 , the PDN GW  309  responds with a proxy binding acknowledgement  227  and updates its mobility binding which effectively switches the DSMIPv6 tunnel from the non-3GPP access network to the PMIPv6 tunnel to the serving GW  317 . In the proxy binding acknowledgement  327 , the PDN GW  309  includes the home IP address or prefix that was assigned to the WTRU  305  earlier. For GTP-based S 5 , the PDN GW  309  responds with a create bearer response message  329  to the serving GW  317 . The create bearer response  329  contains the home IP address or prefix that was assigned to the WTRU  305  earlier. At this point, a PMIPv6/GTP tunnel exists between the serving GW  317  and the PDN GW  309 . 
         [0042]    The PDN GW  309  sends a policy update message  703  to the PCRF  701 . The PCRF responds with a policy update confirmation message  705 . The serving GW  317  then returns a create default bearer response message  329  to the MME  311  that includes the IP address of the WTRU  305  and receives a policy information update  707  from the PCRF  701 . This message  329  also serves as an indication to the MME  311  that the binding was successful. The ePDG  307  sends a message to the non-3GPP IP access  301  to release resources  709 . A release acknowledgement message  711  is returned to the ePDG  307 . The MME  311  sends an attach accept message  331  to the WTRU  305  through 3GPP access  303 . The 3GPP access system  303  initiates radio bearer setup procedures and the 3GPP access system responds with an Attach Complete Message  331 . The WTRU  305  may send a binding update  321  to the PDN GW  309  to de-register its DSMIPv6 binding  325  that was created while the WTRU  305  was in untrusted non-3GPP IP access  301 . The WTRU  305  may send IKEv2 messages if necessary to tear down its system aspects (SA) with the ePDG  307 . 
         [0043]    An enhanced handover procedure from a 3GPP network to an untrusted non-3GPP network through the S 2   b  interface shown in  FIG. 4  is shown in  FIGS. 8A and 8B . The WTRU  401  is connected to the 3GPP network through the serving GW  403  via a PMIPv6 Tunnel  405  to the PDN GW  407  when handover is initiated. The WTRU attaches to the non-3GPP network  411 . Authentication of the WTRU  401  is performed by the HSS/AAA  409  on the 3GPP system. IKEv2 authorization and tunnel setup  415  between the WTRU  401  and the ePDG  413  is then established. A proxy binding update message  417  is sent to the PDN GW  407 . The proxy binding acknowledgement message  419  is returned to the ePDG  413 . The PDN GW  407  sends a policy update message  803  to the PCRF  801 . The PCRF  801  responds with policy update confirmation message  805 . The policy information update message  807  is sent from the PCRF  801  to the ePDG  413 , and the ePDG  413  returns a policy update acknowledgement message  809 . The IPsec tunnel setup and address configuration is performed  421  and the PMIPv6 tunnel  423  is established between the ePDG  413  and the PDN GW  407 . The MME  825  sends a message to release the radio access bearer (RAB)  815  to the 3GPP access network  823  The 3GPP network  823  then acknowledges the RAB release  817 . The MME  825  releases RAB and GTP resources  813  serving GW  403 . The serving GW responds with confirmation message  819 . Tunnel endpoints and radio resources between the PDN GW  407  and the serving GW  403  are released  811 . Non-3GPP IP access is now established through an IPsec Tunnel  425  between the WTRU  401  and the ePDG  413  and a PMIPv6 tunnel  427  between the ePDG  413  and the PDN GW  407 . 
         [0044]    The enhanced handover process  900  from 3GPP IP Access to trusted/untrusted non-3GPP IP access over the S 2   c  interface is shown in  FIGS. 9A and 9B . The WTRU  501  is connected to the 3GPP network through the serving GW  503  through a PMIPv6 Tunnel  505  to the PDN GW  507  when handover is initiated. The WTRU attaches to the non-3GPP network  511 . Authentication of the WTRU  501  is done by the HSS/AAA  509  on the 3GPP system. IKEv2 authorization and tunnel setup  515  between the WTRU  501  and the ePDG  513  when the non-3GPP network is untrusted. Alternatively the IKEv2 authorization and tunnel setup  516  may occur between the WTRU  501  and the PDN GW  507  when the non-3GPP network is a trusted network. A proxy binding update message  517  is sent the PDN GW  507 . The proxy binding acknowledgement message  517  is returned to the ePDG  513 . The IPsec tunnel setup and address configuration is performed  521  and the PMIPv6 tunnel  527  is established between the WTRU  401  and the PDN GW  407 . Non-3GPP IP access is now established through an IPsec Tunnel  525  between the WTRU  501  and the ePDG  513  and a PMIPv6 tunnel  527  between the WTRU  501  and the PDN GW  507 . The PDN GW  507  then sends a policy update message  903  to the PCRF  901 . The PCRF  901  returns a policy update confirmation message  905  to the PDN GW  507 . The PCRF  901  sends a policy information update message  907  to the ePDG  513  which responds with a confirmation message  909 . The PDN GW  507  then sends the serving GW  503  a message  911  to release the GTP and RAB resources. The serving GW  503  responds with a GTP and RAB release acknowledgement message  913 . The serving GW then sends a GTP and RAB release message  915  to the MME  923  that sends an acknowledgment  917  to the serving GW  503 . The MME  923  then sends the E-UTRAN network a RAB release  919  which is acknowledged by an acknowledgement message  921 . The GTP tunnel and RAB resources are now released and the WTRU  501  is connected through IPsec tunnel  525  and DSMIPv6 tunnel  527 . 
         [0045]    Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention. The methods or flow charts provided in the present invention may be implemented in a computer program, software, or firmware tangibly embodied in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). 
         [0046]    Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine. 
         [0047]    A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) module.

Technology Classification (CPC): 7