Title of Invention	SYSTEM AND METHOD FOR PROVIDING MOBILITY BETWEEN INTERWORKING WLAN AND EUTRAN ACCESS SYSTEMS
Abstract	This invention relates to the area of Mobility and Handover between heterogeneous wireless networks. The scope of the invention also covers the case when the UE is capable of accessing both the l-WLAN and EUTRAN access systems simultaneously and also the case where the UE is not capable of accessing both the l-WLAN and EUTRAN access systems simultaneously. This invention provides a system and method to perform Mobility between the access systems with optimized authentication procedure using security context transfer between the access systems and also minimize the data loss by buffering the data during the handover. More specifically, this invention provides a system and method to support handover between the l-WLAN and the EUTRAN access systems.

Title of Invention

SYSTEM AND METHOD FOR PROVIDING MOBILITY BETWEEN INTERWORKING WLAN AND EUTRAN ACCESS SYSTEMS

Abstract

Full Text	This invention relates to the area of Mobility and Handover between heterogeneous wireless networks. The scope of the invention also covers the case when the UE is capable of accessing both the l-WLAN and EUTRAN access systems simultaneously and also the case where the UE is not capable of accessing both the l-WLAN and EUTRAN access systems simultaneously. This invention provides a system and method to perform Mobility between the access systems with optimized authentication procedure using security context transfer between the access systems and also minimize the data loss by buffering the data during the handover. More specifically, this invention provides a system and method to support handover between the l-WLAN and the EUTRAN access systems. DESCRIPTION OF RELATED ART The radio access network (RAN), system architecture (SA) and the core terminal (CT) working groups of the third generation partnership project (3GPP) aim to develop an enhanced UTRAN (E-UTRAN) architecture for next generation wireless systems. The E-UTRAN system is required to co-exist with the current second (2G) and third generation (3G) wireless systems, and in particular, support handovers between the existing systems and the newly evolved E-UTRAN system, specified in the 3GPPTR 23.882. The E-UTRAN system is an evolution of the 3GPP UTRAN system, in which the main entities are the user equipment (UE), the enhanced Node B (ENB) and the enhanced GGSN (EGGSN), as shown in the Figure 1. The ENB of the EUTRAN system is expected to have the features of the Node B and the radio network controller (RNC) of the legacy UTRAN system. The EGGSN is expected to have the functionalities of the SGSN and the GGSN of the legacy UTRAN systems. The integrated WLAN (l-WLAN) system specified in the 3GPP TS 23.234 specifications provides a system and method to integrate legacy UTRAN systems with WLAN systems, as shown in the Figure 2. The l-WLAN system allows WLAN users to access 3GPP packet switched services. Currently there is no efficient mechanism specified to provide handover between the l-WLAN and the EUTRAN access systems. SUMMARY OF THE INVENTION The primary object of the invention is to define a system and method to provide handover between the l-WLAN and the EUTRAN access systems. Another object of the invention is to define a method to optimize the network access authentication procedure during handover. It is another object of the invention to buffer the data destined to the UE by the serving AS during handover procedure, and forward the data to the UE after handover procedure to minimize data loss. It is another object of the invention to send the Handover preparation or request message by the UE in the EUTRAN access network to the l-WLAN access network through the EGGSN or any other entity which has the functionality of GGSN and SGSN. It is another object of the invention that Handover preparation or request message sent by the UE from the EUTRAN AS to l-WLAN AS contains the S-bit (indicated whether simultaneous access is supported or not), NAI, accessing RAT type, Authentication Vectors, EGGSN IP address and other parameters relevant to mobility and security mechanism. Authentication Vectors and EGGSN IP address are included by the serving EGGSN while forwarding the Handover preparation or request message. It is another object of the invention to provide signaling interface between the EGGSN and the AAA server to exchange messages between them. It is another object of the invention to store the IP address of the serving EGGSN, active and unused authentication vectors in the AAA server corresponding to the UE, if HO request is from the EUTRAN network. It is another object of the invention to assign or obtain and send an IP address by the AAA server to the UE while sending the Handover accept or response message. It is another object of the invention to relay the IP address sent by the AAA server to the UE through the Handover command by the EGGSN. It is another object of the invention to resolve the W-APN and sent the list of PDGs IP addresses to the UE through the HO command by the EGGSN or alternatively EGGSN can select a particular PDG and send the IP address of the selected PDG to the UE through the HO command. It is another object of the invention to derive tunnel authentication keys using the active EUTRAN network access authentication keys by the UE and the AAA server for l-WLAN access authentication. It is another object of the invention to send the IP address of the serving EGGSN stored by the AAA server to the PDG during the tunnel establishment procedure. Using the IP address, PDG contacts the serving EGGSN to retrieve the buffered packet destined to the UE. It is another object of the invention to trigger the EGGSN to release the radio resource of the UE in the EUTRAN by the AAA server after establishing tunnel towards the PDG. It is another object of the invention to release the IP address of the UE if MIP based It is another object of the invention to bicast the UE destine packets to the l-WLAN by the EGGSN, incase of UE capable of simultaneous access. It is another object of the invention to intimate to the core network entities, whether UE is capable of simultaneous access. It is another object of the invention to detach the previous access system by the UE after establishing the connection with the other access system. It is another object of the invention to initiate buffering of the data at the PDG by the UE through a new IKEv2 notification payload or through some other signaling message like MIP buffer management mechanism. It is another object of the invention that RAU message or alternatively any initial L3 message after the L2 connection , send by the UE during handover from the l-WLAN to the EUTRAN AS contains the S-bit, NAI, accessing RAT type, PDG IP address and other parameters relevant to mobility and security mechanism. It is another object of the invention to retrieve the active Keys from the AAA server by the EGGSN to authenticate the UE to access EUTRAN. The present invention is related to the scenario where a UE handover from the l-WLAN to the EUTRAN access networks and also from the EUTRAN to the l-WLAN Access system. The method of the invention comprises of mechanisms that provides mobility solution for the UE capable of simultaneous access and also for the UE which cannot access the access systems simultaneously. This invention also includes a mechanism to utilize the active authentication key in one access system to be used in the other access system to optimize the authentication procedure during handover. Accordingly this invention explains a method and system for providing mobility between interworking WLAN and EUTRAN access systems where handover from the EUTRAN to the l-WLAN access system involves UE sending periodic or event based measurements to the EUTRAN network wherein if the UE measurement is below the threshold or if EUMTS RAT cannot be continued, then EGGSN/ENB requests the UE to start scanning other RATs or alternatively by L2 or other means and UE decides that the EUTRAN cannot be continued and starts scanning the other RATs. The UE directly send the HO request to the AAA sever, through EGGSN and the packet is routed to the home AAA server by resolving the NAI where the HO request message contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN and alternatively the UE sends the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. The said measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s formed by the UE according to the current ongoing applications. EGGSN resolves IP addresses of the PDG using the W-APN(s) and the HO request is sent to AAA server using NAI where the HO request sent by the EGGSN contains the NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN. AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP optional Address and the AAA server sends the HO accept message to the EGGSN where the AAA server assigns new IP address to the UE and include the IP address in the HO accept message where optionally, AAA server specify the PDG IP address in the HO accept message, for the UE to establish the tunnel. The EGGSN sends the HO command to the UE and if the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command and where if the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command. If S-bit is off, then the EGGSN starts buffering the packets destined to the UE and if S-bit is on, the EGGSN does not buffer the data destined to the UE. After receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG and the UE selects the IP address of the PDG from the list provided by the EGGSN or UE resolve the IP addresses of the PDGs. The UE uses the active keys to derive the authentication keys and send the AUTH payload, to eliminate the EAP authentication procedure for IPsec tunnel establishment. The UE performs the MIP registration procedure and registers with the EGGSN where the UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and l-WLAN assigned IP address as the Co-CoA. The MIP registration is done for FA-CoA where the MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN. For applications initiated by the UE in the l-WLAN, the UE uses the l-WLAN assigned IP address as the source IP address, and the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE uses the reverse tunneling. AAA uses the active keys provided by the EGGSN to derive the tunnel authentication keys and pass the said keys to the PDG for authentication where the AAA server includes the EGGSN IP address in the Access Accept message. AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains the new information about the UE in the HSS from the HSS before updating. The UE uses the AAA MIP registration procedure to do MIP registration during the IPsec tunnel establishment procedure where the MIP registration authenticator is generated from the active network access keys where the AAA forwards the MIP registration message to EGGSN and the EGGSN registers the UE and send the MIP ACK message to the UE via PDG. After successful authentication and tunnel establishment procedure, if UE is not capable of simultaneous access then AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE and if the UE is capable of simultaneous access then the UE starts EUMTS detach procedure. The PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA and if the EGGSN buffered the packets for the UE, then the EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE where if the UE is capable of simultaneous access, then the EGGSN starts bicasting the packets to both EUTRAN and l-WLAN access systems. After start receiving the packets from the EGGSN, the UE does MIP based route optimization procedure with the CN, and if CN supports MIP and tunnel overhead is not considered to be disadvantage. If no active TCP connections were present, then the UE does SIP based terminal mobility procedure, and if it has any active IMS based sessions and avoids the MIP based mobility procedure the UE intimates the release of IP to the EGGSN in the HO confirm message. The HO complete message is sent within the IKEv2 or with any new signaling protocol and if MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol and the PDG relays the HO complete message to the EGGSN. Accordingly the invention also explains a method and a system for providing mobility between interworking WLAN and EUTRAN access systems where handover from the l-WLAN to the EUTRAN access system involves the UE start scanning the other RAT and deciding to attach with the EUMTS AS based on the signal strength of l-WLAN or by other means. If the UE is not capable of simultaneous access, then the UE intimate the PDG to buffer the packets destined to the UE through a new IKEv2 notification payload or through a signalling message like MIP buffer management mechanism where optionally UE request the PDG to close the IPsec tunnel and resources reserved for the UE and the PDG starts buffering the packets destined to the UE. The UE establish L2/RRC connection with the EUMTS network and the UE sends the RAU message or alternatively any initial L3 message after the L2 connection, including the HO preparation message containing S-bit, l-WLAN ID, NAI and the PDG IP address where the user part of the NAI contains the IMSI or pseudonym or re-authentication id. EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the active AKA keys and also unused AVs from the AAA server where EGGSN updates the HSS about the new location of the UE. Optionally the HSS/AAA request the PDG to release the tunnel created for the UE, if UE is not capable of simultaneous access. EGGSN starts the integrity/ciphering using the active AKA keys and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request. EGGSN establish a tunnel with the PDG and if the S bit is off then EGGSN request the PDG to forward all the packets destined to the UE and the PDG tunnels the buffered packets to the EGGSN and then EGGSN forwards to the UE where if the S-bit is on, then the PDG starts bicasting the packets destined to the UE. After start receiving the packets through the EGGSN, if the UE is capable of simultaneous access, then the UE close the l-WLAN tunnel and the UE does MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. If no active TCP connections are present, then the UE does SIP based terminal mobility procedure, and if UE has any active IMS based sessions and avoid the MIP based mobility procedure then the UE intimates the release of IP to the EGGSN in the HO confirm message where if MIP based solution is used then the UE just confirms the HO by sending the HO complete message and the EGGSN relays the HO complete message to the PDG. These and other objects, features and advantages of the present invention will become more readily apparent from the detailed description taken in conjunction with the drawings and the claims. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS Figure 1 illustrates the EUTRAN system architecture and network elements Figure 2 illustrates the IWLAN system architecture and network elements Figure 3 illustrates the sequence of the message flow during handover from the EUTRAN AS to the l-WLAN AS, when the UE is not capable of simultaneous access. Figure 4 illustrates the sequence of the message flow during handover from the EUTRAN AS to the l-WLAN AS, when the UE is capable of simultaneous access. Figure 5 illustrates the sequence of the message flow during handover from the l-WLAN AS to the EUTRAN AS, when the UE is not capable of simultaneous access. Figure 6 illustrates the sequence of the message flow during handover from the l-WLAN AS to the EUTRAN AS, when the UE is capable of simultaneous access. DETAILED DESCRIPTION OF THE INVENTION A preferred embodiment of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail. The present invention provides a system and method for supporting mobility between the EUTRAN access system and the l-WLAN access system and optionally uses MIP protocol to support the mobility. The method of the invention comprises of mechanisms to move between the EUTRAN access system and the l-WLAN access system when the UE have the capability of simultaneous access and also when the UE does not have capability to access simultaneously. The invention is operated as detailed below: Handover from the EUTRAN to the l-WLAN access system 1. UE sends periodic or event based measurements to the EUTRAN network. If EGGSN finds that UE measurement is below the threshold or EGGSN decides by any other mean that EUMTS RAT cannot be continued, then EGGSN/ENB can request the UE to start scanning other RATs or alternatively oy LZ or by some other means, the UE decides that the EUTRAN cannot be continued and starts scanning the other RATs. UE directly send the HO request to the AAA sever, through EGGSN. The packet can be routed to the home AAA server by resolving the NAI. HO request message contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN) or alternatively the UE may send the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. This measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s (formed by the UE according to the current ongoing application/s). Optionally EGGSN resolves IP addresses of the PDG using the W-APN(s). The HO request is sent to AAA server using NAI. The HO request sent by the EGGSN contains the NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN). AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP Address (Optional). The AAA server then sends the HO accept message to the EGGSN. The AAA server may assign new IP address (the AAA server may assign multiple new IP addresses, if more than one sessions are active) to the UE and include the IP address in the HO accept message. Optionally AAA server may specify the PDG IP address in the HO accept message, for the UE to establish the tunnel. The EGGSN then sends the HO command to the UE. If the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command. If the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command. If S-bit is off, then the EGGSN starts buffering the packets destined to the UE. If S-bit is on, the EGGSN does not buffer the data destined to the UE. 7. After receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG. The UE may select the IP address of the PDG from the list provided by the EGGSN or UE by itself can resolve the IP addresses of the PDGs. UE uses the active keys to derive the authentication keys and send the AUTH payload, so that UE eliminates the EAP authentication procedure for IPsec tunnel establishment. 8. The UE performs the MIP like registration procedure and registers with the EGGSN. In this scenario, EGGSN have the functionality like HA and PDG have the functionality like FA, for MIPv4 like procedure. The UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and also l-WLAN assigned IP address as the Co-CoA. The MIP registration is done for FA-CoA to avoid tunnel overhead. The MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN. For applications initiated by the UE in the l-WLAN, the UE may use the l-WLAN assigned IP address as the source IP address, so the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE may use the reverse tunneling, that is the packets will be tunneled by the PDG (FA) to the EGGSN (HA), then EGGSN forwards the packets to the correspondent node. 9. AAA also uses the same active keys provided by the EGGSN to derive the tunnel authentication keys and pass it to the PDG for authentication. AAA server includes the EGGSN IP address in the Access Accept message. As AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains from the HSS before updating the new information about the UE in the HSS. 10. Alternatively to step 8 and 9, the UE can use the AAA MIP Registration procedure to do MIP registration during the IPsec tunnel establishment procedure. Here the MIP registration authenticator is generated from the active network access keys. AAA forwards the MIP registration message to EGGSN. The EGGSN registers the UE and send the MIP ACK message to the UE via PDG. 11. After successful authentication and tunnel establishment procedure, AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE, if UE is not capable of simultaneous access. If the UE is capable of simultaneous access then the UE starts EUMTS detach procedure. 12. The PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA. If the EGGSN buffered the packets for the UE, then the EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE. If the UE is capable of simultaneous access, then the EGGSN starts bicasting the packets to both EUTRAN and l-WLAN access systems. 13. After start receiving the packets from the EGGSN, the UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. 14. If no active TCP connections were present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. The HO complete message is sent within the IKEv2 or with any new signaling protocol. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol. The PDG relays the HO complete message to the EGGSN. Handover from the l-WLAN to the EUTRAN access system 1. Based on the signal strength of l-WLAN or by other means, the UE start scanning the other RAT and decided to attach with the EUMTS AS. 2. If the UE is not capable of simultaneous access, then the UE intimate the PDG to buffer the packets destined to it through a new IKEv2 notification payload or through some other signalling message like MIP buffer management mechanism. Optionally UE may request the PDG to close the IPsec tunnel and resources reserved for this UE. The PDG starts buffering the packets destined to the UE. 3. The UE establish L2/RRC connection with the EUMTS network. Then the UE send the RAU message or alternatively any initial L3 message after the L2 connection , including the HO preparation message containing S-bit, l-WLAN ID, NAI and the PDG IP address. The user part of the NAI contains the IMSI or pseudonym or re-authentication id. 4. EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the active AKA keys and also unused AVs from the AAA server. EGGSN updates the HSS about the new location of the UE. 5. Optionally the HSS/AAA request the PDG to release the tunnel created for the UE, if UE not capable of simultaneous access. 6. EGGSN starts the integrity/ciphering using the active AKA keys and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request. 7. EGGSN establish a tunnel with the PDG and if the S (simultaneous) bit is OTT then EGGSN request the PDG to forward all the packets destined to the UE. The PDG tunnels the buffered packets to the EGGSN and then EGGSN forwards to the UE. If the S-bit is on, then the PDG starts bicasting the packets destined to the UE. 8. After start receiving the packets through the EGGSN, if the UE is capable of simultaneous access, then the UE will close the l-WLAN tunnel. The UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. 9. If no active TCP connections are present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message. 10.The EGGSN relays the HO complete message to the PDG. An illustrative Example for the operation of the invention: An illustrative example for operating the invention is given here. We consider handover between the EUTRAN and the l-WLAN for the cases when the UE is capable of simultaneous access and also when the UE is not capable of simultaneous access. Handover between the EUTRAN to the l-WLAN (Non Simultaneous Access) The message flows/sequence illustrated in Figure 3 is as below: 1. UE sends periodic or event based measurements to the ENB/EGGSN. 2. a. If EGGSN finds that UE measurement is below the threshold or EGGSN decides by any other mean that EUTRAN cannot be continued, then EGGSN/ENB can request the UE to start scanning other RATs. b. By L2 or by some other means, the UE decides that the EUTRAN cannot be continued and starts scanning the other RATs. 3. a. UE can directly send the HO request to the AAA sever, through EGGSN. The packet can be routed to the home AAA server by resolving the NAI. HO request message contains the NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN). b. UE may send the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. This measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s (formed by the UE according to the current ongoing application/s). Optionally EGGSN resolve IP addresses of the PDG using the W-APN(s). The HO request is sent to AAA server using NAI. The HO request sent by the EGGSN contains the NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN). 4. AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP Address (Optional). The AAA server then sends the HO accept message to the EGGSN. The AAA server may assign new IP address to the UE (the AAA server may assign multiple new IP addresses, if more than one sessions are active) and include the IP address in the HO accept message. Optionally AAA server may specify the PDG IP address in the HO accept message, for the UE to establish the tunnel. 5. The EGGSN then sends the HO command to the UE. If the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command. If the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command. 6. EGGSN starts buffering the packets destined to the UE. 7. a. After receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG. The UE may select the IP address of the PDG from the list provided by the EGGSN or UE by itself can resolve the IP addresses of the PDGs. The UE uses the active CK and IK to derive the MSK and directly calculates and send the IKE AUTH payload, so that UE eliminates the EAP authentication procedure for IPsec tunnel establishment. The UE performs the MIP like registration procedure and registers with the EGGSN. In this scenario EGGSN have the functionality like HA and PDG have the functionality like FA, for MIPv4 like procedures. The UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and also l-WLAN assigned IP address as the Co-CoA. The MIP registration is done for FA-CoA to avoid tunnel overhead. The MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN. For applications initiated by the UE in the l-WLAN, the UE may use the l-WLAN assigned IP address as the source IP address, so the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE may use the reverse tunneling, that is the packets will be tunneled by the PDG (FA) to the EGGSN (HA), then EGGSN forwards the packets to the correspondent node. b. Alternatively UE can use the AAA MIP Registration procedure to do MIP registration during the IPsec tunnel establishment procedure. Here the MSK generated from the active CK and IK will be used to authenticate the MIP registration message. 8. a. AAA also uses the same active CK and IK provided by the EGGSN to derive the MSK and pass it to the PDG for authentication. AAA server includes the EGGSN IP address in the Access Accept message. As AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains from the HSS before updating the new information about the UE in the HSS. b. AAA forwards the MIP registration message to EGGSN. The EGGSN registers the UE and send the MIP Ack message to the UE via PDG. 9. After successful authentication and tunnel establishment procedure, AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE. 10. The PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA 11. The EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE. 12. After start receiving the packets from the EGGSN, the UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. 13. If no active TCP connections were present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. The HO complete message is sent within the IKEv2 or with any new signaling protocol. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol. 14. The PDG relays the HO complete message to the EGGSN. Handover between the EUTRAN to the l-WLAN (Simultaneous Access) The message flows/sequence illustrated in Figure 4 is as below: 1. UE sends periodic or event based measurements to the ENB/EGGSN. 2. a. If EGGSN finds that UE measurement is below the threshold or EGGSN decides by any other mean that EUMTS RAT cannot be continued then EGGSN/ENB can request the UE to start scanning other RATs. b. By L2 or by some other means UE can know that the EUMTS RAT cannot be continued and starts scanning the other RATs. 3. a. UE can directly send the HO request to the AAA sever, through EGGSN. The packet can be routed to the home AAA server by resolving the NAI. HO request message contains the NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN). b. UE may send the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. This measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s (formed by the UE according to the current ongoing application/s). EGGSN resolve IP addresses of the PDG using the W-APN(s) (Optional) The HO request is sent to AAA server using NAI. The HO request sent by the EGGSN contains the NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN). 4. AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP Address (Optional). The AAA server then sends the HO accept message to the EGGSN. The AAA server may assign new IP address to the UE (the AAA server may assign multiple new IP addresses, if more than one sessions are active) and include the IP address in the HO accept message. Optionally AAA server may specify the PDG IP address in the HO accept message, for the UE to establish the tunnel. 5. The EGGSN then sends the HO command to the UE. If the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command. If the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command. 6. a. After receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG. The UE may select the IP address of the PDG from the list provided by the EGGSN or UE by itself can resolve the IP addresses of the PDGs. UE uses the active CK and IK to derive the MSK and directly calculates and send the IKE AUTH payload, so that UE eliminates the EAP authentication procedure for IPsec tunnel establishment. The UE performs the MIP like registration procedure and registers with the EGGSN. In this scenario EGGSN have the functionality like HA and PDG have the functionality like FA, for MIPv4 like procedures. The UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and also l-WLAN assigned IP address as the Co-CoA. The MIP registration is done for FA-CoA to avoid tunnel overhead. The MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN. For applications initiated by the UE in the l-WLAN, the UE may use the l-WLAN assigned IP address as the source IP address, so the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE may use the reverse tunneling, that is the packets will be tunneled by the PDG (FA) to the EGGSN (HA), then EGGSN forwards the packets to the correspondent node. b. Alternatively UE can use the AAA MIP Registration procedure to do MIP registration during the IPsec tunnel establishment procedure. Here the MSK generated from the active CK and IK will be used to authenticate the MIP registration message. 7. a. AAA also uses the same CK and IK provided by the EGGSN to derive the MSK and pass it to the PDG for authentication. AAA server includes the EGGSN IP address in the Access Accept message. As AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains from the HSS before updating the new information about the UE in the HSS. b. AAA forwards the MIP registration message to EGGSN. The EGGSN registers the UE and send the MIP Ack message to the UE via PDG. 8. The PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA 9. The EGGSN starts bicasting the packets to both EUMTS AS and l-WLAN AS. 10. After start receiving the packets through the l-WLAN, the UE initiate the tUM i b aetacn procedure. 11. The EGGSN update the closed status of the UE in the HSS. 12. The UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. 13. If no active TCP connections were present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. The HO complete message is sent within the IKEv2 or with any new signalling protocol. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signalling protocol. 14. The PDG relays the HO complete message to the EGGSN. Handover between the l-WLAN to the EUTRAN (Non Simultaneous Access) The message flows/sequence illustrated in Figure 5 is as below: 1. Based on the signal strength of l-WLAN or by other means, the UE start scanning the other RAT and decided to attach with the EUMTS AS. 2. The UE intimate the PDG to buffer the packets destined to it through a new IKEv2 notification payload or through some other signalling message like MIP buffer management mechanism. Optionally UE may request the PDG to close the IPsec tunnel and resources reserved for this UE. 3. The PDG starts buffering the packets destined to the UE. 4. The UE then start L2 establishment with the EUMTS network. 5. Then the UE send the RAU message or alternatively any initial L3 message after the L2 connection , including the HO preparation message containing l-WLAN ID, NAI and the PDG IP address. The user part of the NAI contains the IMSI or pseudonym or re-authentication id. 6. EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the CK and IK and also unused AVs from the AAA server. EGGSN updates the HSS about the new location of the UE. 7. EGGSN starts the integrity/ciphering using the CK and IK and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request. 8. Optionally the HSS/AAA request the PDG to release the tunnel created for the UE. 9. EGGSN establish a tunnel with the PDG and if the S (simultaneous) bit is off then EGGSN request the PDG to forward all the packets destined to the UE. 10. The PDG tunnels the buffered packets to the EGGSN and then the EGGSN forwards to the UE. 11 .After start receiving the packets through the EGGSN, the UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. 12. If no active TCP connections are present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message. 13. The EGGSN relays the HO complete message to the PDG. Handover between the l-WLAN to the EUTRAN (Simultaneous Access) The message flows/sequence illustrated in Figure 6 is as below: 1. Based on the signal strength of l-WLAN or by other means, the UE start scanning the other RAT and decided to attach with the EUMTS AS. 2. The UE then start L2 establishment with the EUMTS network. 3. Then the UE send the RAU message or alternatively any initial L3 message after the L2 connection, including the HO preparation message containing l-WLAN ID, NAI and the PDG IP address. The user part of the NAI contains the IMSI or pseudonym or re-authentication id. 4. EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the CK and IK and also unused AVs from the AAA server. EGGSN updates the HSS about the new location of the UE. 5. EGGSN starts the integrity/ciphering using the CK and IK and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request. 6. EGGSN establish a tunnel with the PDG and if the S (simultaneous) bit is on then EGGSN request the PDG to bicast the packets destined to the UE. 7. The PDG tunnels the packets to the EGGSN and then the EGGSN forwards to the UE. 8. After start receiving the packets through the EGGSN, the UE sends the IKE delete message to close IPsec tunnel and stop bicasting the packets. 9. The PDG updates the HSS about the l-WLAN connection close. 10. The UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. 11. If no active TCP connections are present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message. 12. The EGGSN relays the HO complete message to the PDG. Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention. GLOSSARY OF THE TERMS AND DEFINITIONS THEREOF 3GPP: 3rd Generation Partnership Project AAA: Authentication, Authorization and Accounting AP: Wireless Local Area Network (WLAN) Access Point APN: Access Point Name DNS: Domain Name Server ENB: Evolving Node B EUTRAN: Evolving UMTS Terrestrial Radio Access Network EGGSN: Evolving GGSN FA: Foreign Agent HA: Home Agent, a router on a mobile node's home network that tunnels packets to the mobile node while it is away from home. Home IP Address: An IP address that is assigned for an extended time to a mobile node or for a particular PS service. It remains unchanged regardless of where the node is attached to the Access Network. PLMN: Public Land Mobile Network H-PLMN: Home PLMN HSS: Home Subscription Server IPsec: Internet Protocol Security IKEv2: Internet Key Exchange Protocol version 2. IWLAN: WLAN integrated with a 3GPP network allowing WLAN users to access 3GPP PS services L2: Layer 2 L3: Layer 3 Local IP Address: An address that is routable up to the NGW to deliver and receive the packet by the MN. MIP: Mobile Internet Protocol includes version 4 and version 6 MN: Mobile Node, the end User Equipment (UE) capable of changing its point of attachment from one network or subnet to another. NAI: Network Address Identifier; Node B: The base station in a UMTS network NGW: Network Gate Way is the gateway where the MN initiated IPsec tunnel ends. PDG: Packet Data Gateway SA: Security Association, a simplex (uni-directional) logical connection, created for security purposes. All traffic traversing an SA is provided the same security processing. In IPsec, an SA is an internet layer abstraction implemented through the use of AH or ESP. Remote IP Address: An address used in the data packet encapsulated by the MN initiated secure tunnel. It represents the identity of the MN in the network which the MN is accessing either in Home network or in foreign network. TS: Transport Selector payload of the IKE protocol. User terminal: the end user equipment e.g., the Mobile Station (MS) or User Equipment (UE). UMTS: Universal Mobile Telecommunication System V-PLMN: Visited PLMN WAG: Wireless Access Gateway WLAN UE: The WLAN UE is the UE (equipped with UICC card including (U) SIM) utilized by a 3GPP subscriber to access the WLAN interworking. W-APN: WLAN APN WLAN AN: WLAN Access Network WE CLAIM 1. A method for providing mobility between interworking WLAN and EUTRAN access systems where handover from the EUTRAN to the l-WLAN access system involves UE sending periodic or event based measurements to the EUTRAN network wherein if the UE measurement is below the threshold or if EUMTS RAT cannot be continued, then EGGSN/ENB requests the UE to start scanning other RATs or alternatively by L2 or other means and UE decides that the EUTRAN cannot be continued and starts scanning the other RATs. 2. A method as claimed in claim 1 wherein the UE directly send the HO request to the AAA sever, through EGGSN and the packet is routed to the home AAA server by resolving the NAI or other means where the HO request message contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN and alternatively the UE sends the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. 3. A method as claimed in claim 2 wherein the said measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s formed by the UE according to the current ongoing applications. 4. A method as claimed in claim 3 wherein EGGSN resolves IP addresses of the PDG using the W-APN(s) and the HO request is sent to AAA server using NAI where the HO request sent by the EGGSN contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN. 5. A method as claimed in claim 4 wherein AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP Address and the AAA server sends the HO accept message to the EGGSN where the AAA server assigns new IP address to the UE and include the IP address in the HO accept message where optionally, AAA server specify the PDG IP address in the HO accept message, for the UE to establish the tunnel. 6. A method as claimed in claim 5 wherein the EGGSN sends the HO command to the UE and if the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command and where if the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command. 7. A method as claimed in claim 6 wherein if S-bit is off, then the EGGSN starts buffering the packets destined to the UE and if S-bit is on, the EGGSN does not buffer the data destined to the UE. 8. A method as claimed in claim 7 wherein after receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG and the UE selects the IP address of the PDG from the list provided by the EGGSN or UE resolves the IP addresses of the PDGs where UE uses the EUTRAN network access active keys to derive the authentication keys and send the AUTH payload, to eliminate the EAP authentication procedure for IPsec tunnel establishment by UE. 9. A method as claimed in claim 8 wherein the UE performs the MIP like registration procedure and registers with the EGGSN where the UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and l-WLAN assigned IP address as the Co-CoA. 10. A method as claimed in claim 9 wherein the MIP like registration is done for FA-CoA where the MIP like registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN. 11. A method as claimed in claim 10 wherein for applications initiated by the UE in the l-WLAN, the UE uses the l-WLAN assigned IP address as the source IP address, and the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE uses the reverse tunneling. 12. A method as claimed in claim 11 wherein AAA uses the active keys provided by the EGGSN to derive the tunnel authentication keys and pass the said keys to the PDG for authentication where the AAA server includes the EGGSN IP address in the Access Accept message. 13. A method as claimed in claim 12 wherein AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains the new information about the UE in the HSS from the HSS before updating. 14. A method as claimed in claim 13 wherein the UE uses the AAA MIP registration procedure to do MIP registration during the IPsec tunnel establishment procedure where the MIP registration authenticator is generated from the active network access keys where the AAA forwards the MIP registration message to EGGSN and the EGGSN registers the UE and send the MIP ACK message to the UE via PDG. 15. A method as claimed in claim 14 wherein after successful authentication and tunnel establishment procedure, if UE is not capable of simultaneous access then AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE and if the UE is capable of simultaneous access then the UE starts EUMTS detach procedure. 16. A method as claimed in claim 15 wherein the PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA and if the EGGSN buffered the packets for the UE, then the EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE where if the UE is capable of simultaneous access, then the EGGSN starts bicasting the packets to both EUTRAN and l-WLAN access systems. 17. A method as claimed in claim 16 wherein after start receiving the packets from the EGGSN, the UE does MIP based route optimization procedure with the CN, and if CN supports MIP and tunnel overhead is not considered to be disadvantage. 18. A method as claimed in claim 17 wherein if no active TCP connections were present, then the UE does SIP based terminal mobility procedure, and if it has any active IMS based sessions and avoids the MIP based mobility procedure the UE intimates the release of IP to the EGGSN in the HO confirm message. 19. A method as claimed in claim 18 wherein the HO complete message is sent within the IKEv2 or with any new signaling protocol and if MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol and the PDG relays the HO complete message to the EGGSN. 20. A method for providing mobility between interworking WLAN and EUTRAN access systems where handover from the l-WLAN to the EUTRAN access system involves the UE start scanning the other RAT and deciding to attach with the EUMTS AS based on the signal strength of l-WLAN or by other means. 21. A method as claimed in claim 20 wherein if the UE is not capable of simultaneous access, then the UE intimate the PDG to buffer the packets destined to the UE through a new IKEv2 notification payload or through a signalling message like MIP buffer management mechanism where optionally UE request the PDG to close the IPsec tunnel and resources reserved for the UE and the PDG starts buffering the packets destined to the UE. 22. A method as claimed in claim 21 wherein the UE establish L2/RRC connection with the EUMTS network and the UE sends the RAU message or alternatively any initial L3 message after the L2 connection, including the HO preparation message containing S-bit, l-WLAN ID, NAI and the PDG IP address where the user part of the NAI contains the IMSI or pseudonym or re-authentication id. 23. A method as claimed in claim 22 wherein EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the active AKA keys and also unused AVs from the AAA server where EGGSN updates the HSS about the new location of the UE. 24. A method as claimed in claim 23 wherein Optionally the HSS/AAA request the PDG to release the tunnel created for the UE, if UE is not capable of simultaneous access. 25. A method as claimed in claim 24 wherein EGGSN starts the integrity/ciphering using the active AKA keys and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request. 26. A method as claimed in claim 25 wherein EGGSN establish a tunnel with the PDG and if the S bit is off then EGGSN request the PDG to forward all the packets destined to the UE and the PDG tunnels the buffered packets to the EGGSN and then EGGSN forwards to the UE where if the S-bit is on, then the PDG starts bicasting the packets destined to the UE. 27. A method as claimed in claim 26 wherein after start receiving the packets through the EGGSN, if the UE is capable of simultaneous access, then the UE close the l-WLAN tunnel and the UE does MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. 28. A method as claimed in claim 27 wherein if no active TCP connections are present, then the UE does SIP based terminal mobility procedure, and if UE has any active IMS based sessions and avoid the MIP based mobility procedure then the UE intimates the release of IP to the EGGSN in the HO confirm message where if MIP based solution is used then the UE just confirms the HO by sending the HO complete message and the EGGSN relays the HO complete message to the PDG. 29. A system for providing mobility between interworking WLAN and EUTRAN access systems where handover from the EUTRAN to the l-WLAN access system involves a UE which sends periodic or event based measurements to the EUTRAN network wherein if the UE measurement is below the threshold or if EUMTS RAT cannot be continued, then EGGSN/ENB requests the UE to start scanning other RATs or alternatively by L2 or other means and UE decides that the EUTRAN cannot be continued and starts scanning the other RATs. 30. A system as claimed in claim 29 wherein the UE directly send the HO request to the AAA sever, through EGGSN and the packet is routed to the home AAA server by resolving the NAI where the HO request message contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN and alternatively the UE sends the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. H.A system as claimed in claim 29 wherein the said measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s formed by the UE according to the current ongoing applications. i2. A system as claimed in claim 31 wherein EGGSN resolves IP addresses of the PDG using the W-APN(s) and the HO request is sent to AAA server using NAI where the HO request sent by the EGGSN contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN. 3. A system as claimed in claim 32 wherein AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP optional Address and the AAA server sends the HO accept message to the EGGSN where the AAA server assigns new IP address to the UE and include the IP address in the HO accept message where optionally, AAA server specify the PDG IP address in the HO accept message, for the UE to establish the tunnel. 34. A system as claimed in claim 33 wherein the EGGSN sends the HO command to the UE and if the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command and where if the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command. 35. A system as claimed in claim 34 wherein if S-bit is off, then the EGGSN starts buffering the packets destined to the UE and if S-bit is on, the EGGSN does not buffer the data destined to the UE. 36. A system as claimed in claim 35 wherein after receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG and the UE selects the IP address of the PDG from the list provided by the EGGSN or UE and resolve the IP addresses of the PDGs where UE uses the active keys to derive the authentication keys and send the AUTH payload, to eliminate the EAP authentication procedure for IPsec tunnel establishment by UE. 37. A system as claimed in claim 36 wherein the UE performs the MIP registration procedure and registers with the EGGSN where the UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and l-WLAN assigned IP address as the Co-CoA. 38. A system as claimed in claim 37 wherein the MIP registration is done for FA-CoA where the MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN. 39. A system as claimed in claim 38 wherein for applications initiated by the UE in the l-WLAN, the UE uses the l-WLAN assigned IP address as the source IP address, and the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE uses the reverse tunneling. 40. A system as claimed in claim 39 wherein AAA uses the active keys provided by the EGGSN to derive the tunnel authentication keys and pass the said keys to the PDG for authentication where the AAA server includes the EGGSN IP address in the Access Accept message. 41 .A system as claimed in claim 40 wherein AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains the new information about the UE in the HSS from the HSS before updating. 42. A system as claimed in claim 41 wherein the UE uses the AAA MIP registration procedure to do MIP registration during the IPsec tunnel establishment procedure where the MIP registration authenticator is generated from the active network access keys where the AAA forwards the MIP registration message to EGGSN and the EGGSN registers the UE and send the MIP ACK message to the UE via PDG. 43. A system as claimed in claim 42 wherein after successful authentication and tunnel establishment procedure, if UE is not capable of simultaneous access then AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE and if the UE is capable of simultaneous access then the UE starts EUMTS detach procedure. 44. A system as claimed in claim 43 wherein the PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA and if the EGGSN buffered the packets for the UE, then the EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE where if the UE is capable of simultaneous access, then the EGGSN starts bicasting the packets to both EUTRAN and l-WLAN access systems. 45. A system as claimed in claim 44 wherein after start receiving the packets from the EGGSN, the UE does MIP based route optimization procedure with the CN, and if CN supports MIP and tunnel overhead is not considered to be disadvantage. 46. A system as claimed in claim 45 wherein if no active TCP connections were present, then the UE does SIP based terminal mobility procedure, and if it has any active IMS based sessions and avoids the MIP based mobility procedure the UE intimates the release of IP to the EGGSN in the HO confirm message. 47. A system as claimed in claim 46 wherein the HO complete message is sent within the IKEv2 or with any new signaling protocol and if MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol and the PDG relays the HO complete message to the EGGSN. 48. A system for providing mobility between interworking WLAN and EUTRAN access systems where handover from the l-WLAN to the EUTRAN access system involves the UE start scanning the other RAT and deciding to attach with the EUMTS AS based on the signal strength of l-WLAN or by other means. 49.A system as claimed in claim 48 wherein if the UE is not capable of simultaneous access, then the UE intimate the PDG to buffer the packets destined to the UE through a new IKEv2 notification payload or through a signalling message like MIP buffer management mechanism where optionally UE request the PDG to close the IPsec tunnel and resources reserved for the UE and the PDG starts buffering the packets destined to the UE. 50. A system as claimed in claim 49 wherein the UE establish L2/RRC connection with the EUMTS network and the UE sends the RAU message or alternatively any initial L3 message after the L2 connection, including the HO preparation message containing S-bit, l-WLAN ID, NAI and the PDG IP address where the user part of the NAI contains the IMSI or pseudonym or re-authentication id. 51. A system as claimed in claim 50 wherein EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the active AKA keys and also unused AVs from the AAA server where EGGSN updates the HSS about the new location of the UE. 52. A system as claimed in claim 51 wherein Optionally the HSS/AAA request the PDG to release the tunnel created for the UE, if UE is not capable of simultaneous access. 53. A system as claimed in claim 52 wherein EGGSN starts the integrity/ciphering using the active AKA keys and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request. 54. A system as claimed in claim 53 wherein EGGSN establish a tunnel with the PDG and if the S bit is off then EGGSN request the PDG to forward all the packets destined to the UE and the PDG tunnels the buffered packets to the EGGSN and then EGGSN forwards to the UE where if the S-bit is on, then the PDG starts bicasting the packets destined to the UE. 55. A system as claimed in claim 54 wherein after start receiving the packets through the EGGSN, if the UE is capable of simultaneous access, then the UE close the l-WLAN tunnel and the UE does MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. 56. A system as claimed in claim 55 wherein if no active TCP connections are present, then the UE does SIP based terminal mobility procedure, and if UE has any active IMS based sessions and avoid the MIP based mobility procedure then the UE intimates the release of IP to the EGGSN in the HO confirm message where if MIP based solution is used then the UE just confirms the HO by sending the HO complete message and the EGGSN relays the HO complete message to the PDG. 57. A system as claimed in claim 1 wherein the said method includes solutions for the UE.which is capable of simultaneous and non-simultaneous access. 58. A system as claimed in claim 1 wherein the said method includes to provide signaling interface between the EGGSN and the AAA server to exchange messages between them. 59. A system as claimed in claim 1 wherein the said method includes to send the IP address of the EGGSN stored by the AAA server to the PDG during the tunnel establishment procedure. Using the EGGSN IP address, PDG contacts the serving EGGSN to retrieve the buffered packet at the EGGSN destined to the UE. 60. A method for providing mobility between interworking WLAN and EUTRAN access systems substantially described particularly with reference to the accompanying drawings. 61. A system for providing mobility between interworking WLAN and EUTRAN access systems substantially described particularly with reference to the accompanying drawings.

Full Text

This invention relates to the area of Mobility and Handover between heterogeneous wireless networks. The scope of the invention also covers the case when the UE is capable of accessing both the l-WLAN and EUTRAN access systems simultaneously and also the case where the UE is not capable of accessing both the l-WLAN and EUTRAN access systems simultaneously. This invention provides a system and method to perform Mobility between the access systems with optimized authentication procedure using security context transfer between the access systems and also minimize the data loss by buffering the data during the handover. More specifically, this invention provides a system and method to support handover between the l-WLAN and the EUTRAN access systems.
DESCRIPTION OF RELATED ART
The radio access network (RAN), system architecture (SA) and the core terminal (CT) working groups of the third generation partnership project (3GPP) aim to develop an enhanced UTRAN (E-UTRAN) architecture for next generation wireless systems. The E-UTRAN system is required to co-exist with the current second (2G) and third generation (3G) wireless systems, and in particular, support handovers between the existing systems and the newly evolved E-UTRAN system, specified in the 3GPPTR 23.882.
The E-UTRAN system is an evolution of the 3GPP UTRAN system, in which the main entities are the user equipment (UE), the enhanced Node B (ENB) and the enhanced GGSN (EGGSN), as shown in the Figure 1. The ENB of the EUTRAN system is expected to have the features of the Node B and the radio network controller (RNC) of the legacy UTRAN system. The EGGSN is expected to have the functionalities of the SGSN and the GGSN of the legacy UTRAN systems.
The integrated WLAN (l-WLAN) system specified in the 3GPP TS 23.234 specifications provides a system and method to integrate legacy UTRAN systems

with WLAN systems, as shown in the Figure 2. The l-WLAN system allows WLAN users to access 3GPP packet switched services.
Currently there is no efficient mechanism specified to provide handover between the l-WLAN and the EUTRAN access systems.
SUMMARY OF THE INVENTION
The primary object of the invention is to define a system and method to provide handover between the l-WLAN and the EUTRAN access systems.
Another object of the invention is to define a method to optimize the network access authentication procedure during handover.
It is another object of the invention to buffer the data destined to the UE by the serving AS during handover procedure, and forward the data to the UE after handover procedure to minimize data loss.
It is another object of the invention to send the Handover preparation or request message by the UE in the EUTRAN access network to the l-WLAN access network through the EGGSN or any other entity which has the functionality of GGSN and SGSN.
It is another object of the invention that Handover preparation or request message sent by the UE from the EUTRAN AS to l-WLAN AS contains the S-bit (indicated whether simultaneous access is supported or not), NAI, accessing RAT type, Authentication Vectors, EGGSN IP address and other parameters relevant to mobility and security mechanism. Authentication Vectors and EGGSN IP address are included by the serving EGGSN while forwarding the Handover preparation or request message.
It is another object of the invention to provide signaling interface between the

EGGSN and the AAA server to exchange messages between them.
It is another object of the invention to store the IP address of the serving EGGSN, active and unused authentication vectors in the AAA server corresponding to the UE, if HO request is from the EUTRAN network.
It is another object of the invention to assign or obtain and send an IP address by the AAA server to the UE while sending the Handover accept or response message.
It is another object of the invention to relay the IP address sent by the AAA server to the UE through the Handover command by the EGGSN.
It is another object of the invention to resolve the W-APN and sent the list of PDGs IP addresses to the UE through the HO command by the EGGSN or alternatively EGGSN can select a particular PDG and send the IP address of the selected PDG to the UE through the HO command.
It is another object of the invention to derive tunnel authentication keys using the active EUTRAN network access authentication keys by the UE and the AAA server for l-WLAN access authentication.
It is another object of the invention to send the IP address of the serving EGGSN stored by the AAA server to the PDG during the tunnel establishment procedure. Using the IP address, PDG contacts the serving EGGSN to retrieve the buffered packet destined to the UE.
It is another object of the invention to trigger the EGGSN to release the radio resource of the UE in the EUTRAN by the AAA server after establishing tunnel towards the PDG.
It is another object of the invention to release the IP address of the UE if MIP based

It is another object of the invention to bicast the UE destine packets to the l-WLAN by the EGGSN, incase of UE capable of simultaneous access.
It is another object of the invention to intimate to the core network entities, whether UE is capable of simultaneous access.
It is another object of the invention to detach the previous access system by the UE after establishing the connection with the other access system.
It is another object of the invention to initiate buffering of the data at the PDG by the UE through a new IKEv2 notification payload or through some other signaling message like MIP buffer management mechanism.
It is another object of the invention that RAU message or alternatively any initial L3 message after the L2 connection , send by the UE during handover from the l-WLAN to the EUTRAN AS contains the S-bit, NAI, accessing RAT type, PDG IP address and other parameters relevant to mobility and security mechanism.
It is another object of the invention to retrieve the active Keys from the AAA server by the EGGSN to authenticate the UE to access EUTRAN.
The present invention is related to the scenario where a UE handover from the l-WLAN to the EUTRAN access networks and also from the EUTRAN to the l-WLAN Access system. The method of the invention comprises of mechanisms that provides mobility solution for the UE capable of simultaneous access and also for the UE which cannot access the access systems simultaneously. This invention also includes a mechanism to utilize the active authentication key in one access system to be used in the other access system to optimize the authentication procedure during handover.

Accordingly this invention explains a method and system for providing mobility between interworking WLAN and EUTRAN access systems where handover from the EUTRAN to the l-WLAN access system involves UE sending periodic or event based measurements to the EUTRAN network wherein if the UE measurement is below the threshold or if EUMTS RAT cannot be continued, then EGGSN/ENB requests the UE to start scanning other RATs or alternatively by L2 or other means and UE decides that the EUTRAN cannot be continued and starts scanning the other RATs. The UE directly send the HO request to the AAA sever, through EGGSN and the packet is routed to the home AAA server by resolving the NAI where the HO request message contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN and alternatively the UE sends the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. The said measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s formed by the UE according to the current ongoing applications. EGGSN resolves IP addresses of the PDG using the W-APN(s) and the HO request is sent to AAA server using NAI where the HO request sent by the EGGSN contains the NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN. AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP optional Address and the AAA server sends the HO accept message to the EGGSN where the AAA server assigns new IP address to the UE and include the IP address in the HO accept message where optionally, AAA server specify the PDG IP address in the HO accept message, for the UE to establish the tunnel. The EGGSN sends the HO command to the UE and if the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command and where if the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command. If S-bit is off, then the EGGSN starts buffering the packets destined to the UE and if S-bit is on, the EGGSN does not buffer the data destined to the UE. After receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG and the UE selects the IP address of the PDG from the list provided by the EGGSN or UE resolve the IP

addresses of the PDGs. The UE uses the active keys to derive the authentication keys and send the AUTH payload, to eliminate the EAP authentication procedure for IPsec tunnel establishment. The UE performs the MIP registration procedure and registers with the EGGSN where the UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and l-WLAN assigned IP address as the Co-CoA. The MIP registration is done for FA-CoA where the MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN. For applications initiated by the UE in the l-WLAN, the UE uses the l-WLAN assigned IP address as the source IP address, and the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE uses the reverse tunneling. AAA uses the active keys provided by the EGGSN to derive the tunnel authentication keys and pass the said keys to the PDG for authentication where the AAA server includes the EGGSN IP address in the Access Accept message. AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains the new information about the UE in the HSS from the HSS before updating. The UE uses the AAA MIP registration procedure to do MIP registration during the IPsec tunnel establishment procedure where the MIP registration authenticator is generated from the active network access keys where the AAA forwards the MIP registration message to EGGSN and the EGGSN registers the UE and send the MIP ACK message to the UE via PDG. After successful authentication and tunnel establishment procedure, if UE is not capable of simultaneous access then AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE and if the UE is capable of simultaneous access then the UE starts EUMTS detach procedure. The PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA and if the EGGSN buffered the packets for the UE, then the EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE where if the UE is capable of simultaneous access, then the EGGSN starts bicasting the packets to both EUTRAN and l-WLAN access systems. After start receiving the packets from the EGGSN, the UE does MIP based route optimization procedure with the CN, and if CN supports MIP and tunnel overhead is not considered to be disadvantage. If no active TCP connections were present, then

the UE does SIP based terminal mobility procedure, and if it has any active IMS based sessions and avoids the MIP based mobility procedure the UE intimates the release of IP to the EGGSN in the HO confirm message. The HO complete message is sent within the IKEv2 or with any new signaling protocol and if MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol and the PDG relays the HO complete message to the EGGSN.
Accordingly the invention also explains a method and a system for providing mobility between interworking WLAN and EUTRAN access systems where handover from the l-WLAN to the EUTRAN access system involves the UE start scanning the other RAT and deciding to attach with the EUMTS AS based on the signal strength of l-WLAN or by other means. If the UE is not capable of simultaneous access, then the UE intimate the PDG to buffer the packets destined to the UE through a new IKEv2 notification payload or through a signalling message like MIP buffer management mechanism where optionally UE request the PDG to close the IPsec tunnel and resources reserved for the UE and the PDG starts buffering the packets destined to the UE. The UE establish L2/RRC connection with the EUMTS network and the UE sends the RAU message or alternatively any initial L3 message after the L2 connection, including the HO preparation message containing S-bit, l-WLAN ID, NAI and the PDG IP address where the user part of the NAI contains the IMSI or pseudonym or re-authentication id. EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the active AKA keys and also unused AVs from the AAA server where EGGSN updates the HSS about the new location of the UE. Optionally the HSS/AAA request the PDG to release the tunnel created for the UE, if UE is not capable of simultaneous access. EGGSN starts the integrity/ciphering using the active AKA keys and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request. EGGSN establish a tunnel with the PDG and if the S bit is off then EGGSN request the PDG to forward all the packets destined to the UE and the PDG tunnels the buffered packets to the EGGSN and then EGGSN forwards to the UE where if the S-bit is on, then the PDG starts

bicasting the packets destined to the UE. After start receiving the packets through the EGGSN, if the UE is capable of simultaneous access, then the UE close the l-WLAN tunnel and the UE does MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage. If no active TCP connections are present, then the UE does SIP based terminal mobility procedure, and if UE has any active IMS based sessions and avoid the MIP based mobility procedure then the UE intimates the release of IP to the EGGSN in the HO confirm message where if MIP based solution is used then the UE just confirms the HO by sending the HO complete message and the EGGSN relays the HO complete message to the PDG.
These and other objects, features and advantages of the present invention will become more readily apparent from the detailed description taken in conjunction with the drawings and the claims.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1 illustrates the EUTRAN system architecture and network elements
Figure 2 illustrates the IWLAN system architecture and network elements
Figure 3 illustrates the sequence of the message flow during handover from the EUTRAN AS to the l-WLAN AS, when the UE is not capable of simultaneous access.
Figure 4 illustrates the sequence of the message flow during handover from the EUTRAN AS to the l-WLAN AS, when the UE is capable of simultaneous access.
Figure 5 illustrates the sequence of the message flow during handover from the l-WLAN AS to the EUTRAN AS, when the UE is not capable of simultaneous access.

Figure 6 illustrates the sequence of the message flow during handover from the l-WLAN AS to the EUTRAN AS, when the UE is capable of simultaneous access.
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will now be explained with reference to the accompanying drawings. It should be understood however that the disclosed embodiment is merely exemplary of the invention, which may be embodied in various forms. The following description and drawings are not to be construed as limiting the invention and numerous specific details are described to provide a thorough understanding of the present invention, as the basis for the claims and as a basis for teaching one skilled in the art how to make and/or use the invention. However in certain instances, well-known or conventional details are not described in order not to unnecessarily obscure the present invention in detail.
The present invention provides a system and method for supporting mobility between the EUTRAN access system and the l-WLAN access system and optionally uses MIP protocol to support the mobility.
The method of the invention comprises of mechanisms to move between the EUTRAN access system and the l-WLAN access system when the UE have the capability of simultaneous access and also when the UE does not have capability to access simultaneously.
The invention is operated as detailed below:
Handover from the EUTRAN to the l-WLAN access system
1. UE sends periodic or event based measurements to the EUTRAN network. If EGGSN finds that UE measurement is below the threshold or EGGSN decides by any other mean that EUMTS RAT cannot be continued, then EGGSN/ENB can request the UE to start scanning other RATs or

alternatively oy LZ or by some other means, the UE decides that the EUTRAN cannot be continued and starts scanning the other RATs.
UE directly send the HO request to the AAA sever, through EGGSN. The packet can be routed to the home AAA server by resolving the NAI. HO request message contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN) or alternatively the UE may send the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. This measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s (formed by the UE according to the current ongoing application/s).
Optionally EGGSN resolves IP addresses of the PDG using the W-APN(s). The HO request is sent to AAA server using NAI. The HO request sent by the EGGSN contains the NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN).
AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP Address (Optional). The AAA server then sends the HO accept message to the EGGSN. The AAA server may assign new IP address (the AAA server may assign multiple new IP addresses, if more than one sessions are active) to the UE and include the IP address in the HO accept message. Optionally AAA server may specify the PDG IP address in the HO accept message, for the UE to establish the tunnel.
The EGGSN then sends the HO command to the UE. If the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command. If the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command.
If S-bit is off, then the EGGSN starts buffering the packets destined to the

UE. If S-bit is on, the EGGSN does not buffer the data destined to the UE.
7. After receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG. The UE may select the IP address of the PDG from the list provided by the EGGSN or UE by itself can resolve the IP addresses of the PDGs. UE uses the active keys to derive the authentication keys and send the AUTH payload, so that UE eliminates the EAP authentication procedure for IPsec tunnel establishment.
8. The UE performs the MIP like registration procedure and registers with the EGGSN. In this scenario, EGGSN have the functionality like HA and PDG have the functionality like FA, for MIPv4 like procedure. The UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and also l-WLAN assigned IP address as the Co-CoA. The MIP registration is done for FA-CoA to avoid tunnel overhead. The MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN. For applications initiated by the UE in the l-WLAN, the UE may use the l-WLAN assigned IP address as the source IP address, so the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE may use the reverse tunneling, that is the packets will be tunneled by the PDG (FA) to the EGGSN (HA), then EGGSN forwards the packets to the correspondent node.
9. AAA also uses the same active keys provided by the EGGSN to derive the tunnel authentication keys and pass it to the PDG for authentication. AAA server includes the EGGSN IP address in the Access Accept message. As AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains from the HSS before updating the new information about the UE in the HSS.

10. Alternatively to step 8 and 9, the UE can use the AAA MIP Registration procedure to do MIP registration during the IPsec tunnel establishment procedure. Here the MIP registration authenticator is generated from the active network access keys. AAA forwards the MIP registration message to EGGSN. The EGGSN registers the UE and send the MIP ACK message to the UE via PDG.
11. After successful authentication and tunnel establishment procedure, AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE, if UE is not capable of simultaneous access. If the UE is capable of simultaneous access then the UE starts EUMTS detach procedure.
12. The PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA. If the EGGSN buffered the packets for the UE, then the EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE. If the UE is capable of simultaneous access, then the EGGSN starts bicasting the packets to both EUTRAN and l-WLAN access systems.
13. After start receiving the packets from the EGGSN, the UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage.
14. If no active TCP connections were present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. The HO complete message is sent within the IKEv2 or with any new signaling protocol. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol. The PDG relays the HO complete message to the EGGSN.

Handover from the l-WLAN to the EUTRAN access system
1. Based on the signal strength of l-WLAN or by other means, the UE start scanning the other RAT and decided to attach with the EUMTS AS.
2. If the UE is not capable of simultaneous access, then the UE intimate the PDG to buffer the packets destined to it through a new IKEv2 notification payload or through some other signalling message like MIP buffer management mechanism. Optionally UE may request the PDG to close the IPsec tunnel and resources reserved for this UE. The PDG starts buffering the packets destined to the UE.
3. The UE establish L2/RRC connection with the EUMTS network. Then the UE send the RAU message or alternatively any initial L3 message after the L2 connection , including the HO preparation message containing S-bit, l-WLAN ID, NAI and the PDG IP address. The user part of the NAI contains the IMSI or pseudonym or re-authentication id.
4. EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the active AKA keys and also unused AVs from the AAA server. EGGSN updates the HSS about the new location of the UE.
5. Optionally the HSS/AAA request the PDG to release the tunnel created for the UE, if UE not capable of simultaneous access.
6. EGGSN starts the integrity/ciphering using the active AKA keys and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request.
7. EGGSN establish a tunnel with the PDG and if the S (simultaneous) bit is

OTT then EGGSN request the PDG to forward all the packets destined to the UE. The PDG tunnels the buffered packets to the EGGSN and then EGGSN forwards to the UE. If the S-bit is on, then the PDG starts bicasting the packets destined to the UE.
8. After start receiving the packets through the EGGSN, if the UE is capable of simultaneous access, then the UE will close the l-WLAN tunnel. The UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage.
9. If no active TCP connections are present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message.
10.The EGGSN relays the HO complete message to the PDG.
An illustrative Example for the operation of the invention:
An illustrative example for operating the invention is given here. We consider handover between the EUTRAN and the l-WLAN for the cases when the UE is capable of simultaneous access and also when the UE is not capable of simultaneous access.
Handover between the EUTRAN to the l-WLAN (Non Simultaneous Access)
The message flows/sequence illustrated in Figure 3 is as below:
1. UE sends periodic or event based measurements to the ENB/EGGSN.
2. a. If EGGSN finds that UE measurement is below the threshold or EGGSN decides by any other mean that EUTRAN cannot be continued, then

EGGSN/ENB can request the UE to start scanning other RATs.
b. By L2 or by some other means, the UE decides that the EUTRAN cannot be continued and starts scanning the other RATs.
3. a. UE can directly send the HO request to the AAA sever, through EGGSN.
The packet can be routed to the home AAA server by resolving the NAI.
HO request message contains the NAI, RAT type, Authentication Vectors
and EGGSN IP address (included by the EGGSN).
b. UE may send the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. This measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s (formed by the UE according to the current ongoing application/s).
Optionally EGGSN resolve IP addresses of the PDG using the W-APN(s).
The HO request is sent to AAA server using NAI. The HO request sent by the EGGSN contains the NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN).
4. AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP Address (Optional). The AAA server then sends the HO accept message to the EGGSN. The AAA server may assign new IP address to the UE (the AAA server may assign multiple new IP addresses, if more than one sessions are active) and include the IP address in the HO accept message. Optionally AAA server may specify the PDG IP address in the HO accept message, for the UE to establish the tunnel.
5. The EGGSN then sends the HO command to the UE. If the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command. If the AAA server sends the IP

address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command.
6. EGGSN starts buffering the packets destined to the UE.
7. a. After receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG. The UE may select the IP address of the PDG from the list provided by the EGGSN or UE by itself can resolve the IP addresses of the PDGs. The UE uses the active CK and IK to derive the MSK and directly calculates and send the IKE AUTH payload, so that UE eliminates the EAP authentication procedure for IPsec tunnel establishment.
The UE performs the MIP like registration procedure and registers with the EGGSN. In this scenario EGGSN have the functionality like HA and PDG have the functionality like FA, for MIPv4 like procedures. The UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and also l-WLAN assigned IP address as the Co-CoA.
The MIP registration is done for FA-CoA to avoid tunnel overhead. The MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN.
For applications initiated by the UE in the l-WLAN, the UE may use the l-WLAN assigned IP address as the source IP address, so the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE may use the reverse tunneling, that is the packets will be tunneled by the PDG (FA) to the EGGSN (HA), then EGGSN forwards the packets to the correspondent node.
b. Alternatively UE can use the AAA MIP Registration procedure to do MIP registration during the IPsec tunnel establishment procedure. Here the

MSK generated from the active CK and IK will be used to authenticate the MIP registration message.
8. a. AAA also uses the same active CK and IK provided by the EGGSN to
derive the MSK and pass it to the PDG for authentication. AAA server
includes the EGGSN IP address in the Access Accept message. As AAA
server stores the serving EGGSN IP address during the HO preparation
procedure or alternatively AAA obtains from the HSS before updating the
new information about the UE in the HSS.
b. AAA forwards the MIP registration message to EGGSN. The EGGSN registers the UE and send the MIP Ack message to the UE via PDG.
9. After successful authentication and tunnel establishment procedure, AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE.
10. The PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA
11. The EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE.
12. After start receiving the packets from the EGGSN, the UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage.
13. If no active TCP connections were present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. The HO complete message is sent within the IKEv2 or with any new signaling

protocol. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol.
14. The PDG relays the HO complete message to the EGGSN.
Handover between the EUTRAN to the l-WLAN (Simultaneous Access)
The message flows/sequence illustrated in Figure 4 is as below:
1. UE sends periodic or event based measurements to the ENB/EGGSN.
2. a. If EGGSN finds that UE measurement is below the threshold or EGGSN decides by any other mean that EUMTS RAT cannot be continued then EGGSN/ENB can request the UE to start scanning other RATs.
b. By L2 or by some other means UE can know that the EUMTS RAT cannot be continued and starts scanning the other RATs.
3. a. UE can directly send the HO request to the AAA sever, through EGGSN.
The packet can be routed to the home AAA server by resolving the NAI.
HO request message contains the NAI, RAT type, Authentication Vectors
and EGGSN IP address (included by the EGGSN).
b. UE may send the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs. This measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s (formed by the UE according to the current ongoing application/s).
EGGSN resolve IP addresses of the PDG using the W-APN(s) (Optional)
The HO request is sent to AAA server using NAI. The HO request sent by

the EGGSN contains the NAI, RAT type, Authentication Vectors and EGGSN IP address (included by the EGGSN).
4. AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP Address (Optional). The AAA server then sends the HO accept message to the EGGSN. The AAA server may assign new IP address to the UE (the AAA server may assign multiple new IP addresses, if more than one sessions are active) and include the IP address in the HO accept message. Optionally AAA server may specify the PDG IP address in the HO accept message, for the UE to establish the tunnel.
5. The EGGSN then sends the HO command to the UE. If the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command. If the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command.
6. a. After receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG. The UE may select the IP address of the PDG from the list provided by the EGGSN or UE by itself can resolve the IP addresses of the PDGs. UE uses the active CK and IK to derive the MSK and directly calculates and send the IKE AUTH payload, so that UE eliminates the EAP authentication procedure for IPsec tunnel establishment.
The UE performs the MIP like registration procedure and registers with the EGGSN. In this scenario EGGSN have the functionality like HA and PDG have the functionality like FA, for MIPv4 like procedures. The UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and also l-WLAN assigned IP address as the Co-CoA.
The MIP registration is done for FA-CoA to avoid tunnel overhead. The

MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN.
For applications initiated by the UE in the l-WLAN, the UE may use the l-WLAN assigned IP address as the source IP address, so the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE may use the reverse tunneling, that is the packets will be tunneled by the PDG (FA) to the EGGSN (HA), then EGGSN forwards the packets to the correspondent node.
b. Alternatively UE can use the AAA MIP Registration procedure to do MIP registration during the IPsec tunnel establishment procedure. Here the MSK generated from the active CK and IK will be used to authenticate the MIP registration message.
7. a. AAA also uses the same CK and IK provided by the EGGSN to derive
the MSK and pass it to the PDG for authentication. AAA server includes
the EGGSN IP address in the Access Accept message. As AAA server
stores the serving EGGSN IP address during the HO preparation
procedure or alternatively AAA obtains from the HSS before updating the
new information about the UE in the HSS.
b. AAA forwards the MIP registration message to EGGSN. The EGGSN registers the UE and send the MIP Ack message to the UE via PDG.
8. The PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA
9. The EGGSN starts bicasting the packets to both EUMTS AS and l-WLAN AS.
10. After start receiving the packets through the l-WLAN, the UE initiate the

tUM i b aetacn procedure.
11. The EGGSN update the closed status of the UE in the HSS.
12. The UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage.
13. If no active TCP connections were present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. The HO complete message is sent within the IKEv2 or with any new signalling protocol. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signalling protocol.
14. The PDG relays the HO complete message to the EGGSN.
Handover between the l-WLAN to the EUTRAN (Non Simultaneous Access)
The message flows/sequence illustrated in Figure 5 is as below:
1. Based on the signal strength of l-WLAN or by other means, the UE start scanning the other RAT and decided to attach with the EUMTS AS.
2. The UE intimate the PDG to buffer the packets destined to it through a new IKEv2 notification payload or through some other signalling message like MIP buffer management mechanism. Optionally UE may request the PDG to close the IPsec tunnel and resources reserved for this UE.
3. The PDG starts buffering the packets destined to the UE.

4. The UE then start L2 establishment with the EUMTS network.
5. Then the UE send the RAU message or alternatively any initial L3 message after the L2 connection , including the HO preparation message containing l-WLAN ID, NAI and the PDG IP address. The user part of the NAI contains the IMSI or pseudonym or re-authentication id.
6. EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the CK and IK and also unused AVs from the AAA server. EGGSN updates the HSS about the new location of the UE.
7. EGGSN starts the integrity/ciphering using the CK and IK and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request.
8. Optionally the HSS/AAA request the PDG to release the tunnel created for the UE.
9. EGGSN establish a tunnel with the PDG and if the S (simultaneous) bit is off then EGGSN request the PDG to forward all the packets destined to the UE.
10. The PDG tunnels the buffered packets to the EGGSN and then the EGGSN forwards to the UE.
11 .After start receiving the packets through the EGGSN, the UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage.
12. If no active TCP connections are present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and

can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message.
13. The EGGSN relays the HO complete message to the PDG.
Handover between the l-WLAN to the EUTRAN (Simultaneous Access)
The message flows/sequence illustrated in Figure 6 is as below:
1. Based on the signal strength of l-WLAN or by other means, the UE start scanning the other RAT and decided to attach with the EUMTS AS.
2. The UE then start L2 establishment with the EUMTS network.
3. Then the UE send the RAU message or alternatively any initial L3 message after the L2 connection, including the HO preparation message containing l-WLAN ID, NAI and the PDG IP address. The user part of the NAI contains the IMSI or pseudonym or re-authentication id.
4. EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the CK and IK and also unused AVs from the AAA server. EGGSN updates the HSS about the new location of the UE.
5. EGGSN starts the integrity/ciphering using the CK and IK and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request.
6. EGGSN establish a tunnel with the PDG and if the S (simultaneous) bit is on then EGGSN request the PDG to bicast the packets destined to the UE.

7. The PDG tunnels the packets to the EGGSN and then the EGGSN
forwards to the UE.
8. After start receiving the packets through the EGGSN, the UE sends the IKE delete message to close IPsec tunnel and stop bicasting the packets.
9. The PDG updates the HSS about the l-WLAN connection close.
10. The UE may do MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage.

11. If no active TCP connections are present, then the UE can do SIP based terminal mobility procedure, if it has any active IMS based sessions and can avoid the MIP based mobility procedure. The UE can intimate the release of IP to the EGGSN in the HO confirm message. If MIP based solution is used then the UE just confirms the HO by sending the HO complete message.
12. The EGGSN relays the HO complete message to the PDG.
Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be affected therein by one skilled in the art without departing from the scope or spirit of the invention.

GLOSSARY OF THE TERMS AND DEFINITIONS THEREOF
3GPP: 3rd Generation Partnership Project
AAA: Authentication, Authorization and Accounting
AP: Wireless Local Area Network (WLAN) Access Point
APN: Access Point Name
DNS: Domain Name Server
ENB: Evolving Node B
EUTRAN: Evolving UMTS Terrestrial Radio Access Network
EGGSN: Evolving GGSN
FA: Foreign Agent
HA: Home Agent, a router on a mobile node's home network that tunnels packets to
the mobile node while it is away from home.
Home IP Address: An IP address that is assigned for an extended time to a mobile
node or for a particular PS service. It remains unchanged regardless of where the
node is attached to the Access Network.
PLMN: Public Land Mobile Network
H-PLMN: Home PLMN
HSS: Home Subscription Server
IPsec: Internet Protocol Security
IKEv2: Internet Key Exchange Protocol version 2.
IWLAN: WLAN integrated with a 3GPP network allowing WLAN users to access
3GPP PS services
L2: Layer 2
L3: Layer 3
Local IP Address: An address that is routable up to the NGW to deliver and
receive the packet by the MN.
MIP: Mobile Internet Protocol includes version 4 and version 6
MN: Mobile Node, the end User Equipment (UE) capable of changing its point of
attachment from one network or subnet to another.
NAI: Network Address Identifier;
Node B: The base station in a UMTS network

NGW: Network Gate Way is the gateway where the MN initiated IPsec tunnel ends.
PDG: Packet Data Gateway
SA: Security Association, a simplex (uni-directional) logical connection, created for
security purposes. All traffic traversing an SA is provided the same security
processing. In IPsec, an SA is an internet layer abstraction implemented through
the use of AH or ESP.
Remote IP Address: An address used in the data packet encapsulated by the MN
initiated secure tunnel. It represents the identity of the MN in the network which the
MN is accessing either in Home network or in foreign network.
TS: Transport Selector payload of the IKE protocol.
User terminal: the end user equipment e.g., the Mobile Station (MS) or User
Equipment (UE).
UMTS: Universal Mobile Telecommunication System
V-PLMN: Visited PLMN
WAG: Wireless Access Gateway
WLAN UE: The WLAN UE is the UE (equipped with UICC card including (U) SIM)
utilized by a 3GPP subscriber to access the WLAN interworking.
W-APN: WLAN APN
WLAN AN: WLAN Access Network

WE CLAIM
1. A method for providing mobility between interworking WLAN and EUTRAN access systems where handover from the EUTRAN to the l-WLAN access system involves UE sending periodic or event based measurements to the EUTRAN network wherein if the UE measurement is below the threshold or if EUMTS RAT cannot be continued, then EGGSN/ENB requests the UE to start scanning other RATs or alternatively by L2 or other means and UE decides that the EUTRAN cannot be continued and starts scanning the other RATs.
2. A method as claimed in claim 1 wherein the UE directly send the HO request to the AAA sever, through EGGSN and the packet is routed to the home AAA server by resolving the NAI or other means where the HO request message contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN and alternatively the UE sends the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs.
3. A method as claimed in claim 2 wherein the said measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s formed by the UE according to the current ongoing applications.
4. A method as claimed in claim 3 wherein EGGSN resolves IP addresses of the PDG using the W-APN(s) and the HO request is sent to AAA server using NAI where the HO request sent by the EGGSN contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN.
5. A method as claimed in claim 4 wherein AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP Address and the AAA server sends the HO accept message to the EGGSN where the AAA server assigns new IP address to the UE and include the IP address in the HO accept message where optionally, AAA server specify the PDG IP address in the HO accept message, for the UE to establish the tunnel.

6. A method as claimed in claim 5 wherein the EGGSN sends the HO command to the UE and if the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command and where if the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command.
7. A method as claimed in claim 6 wherein if S-bit is off, then the EGGSN starts buffering the packets destined to the UE and if S-bit is on, the EGGSN does not buffer the data destined to the UE.
8. A method as claimed in claim 7 wherein after receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG and the UE selects the IP address of the PDG from the list provided by the EGGSN or UE resolves the IP addresses of the PDGs where UE uses the EUTRAN network access active keys to derive the authentication keys and send the AUTH payload, to eliminate the EAP authentication procedure for IPsec tunnel establishment by UE.
9. A method as claimed in claim 8 wherein the UE performs the MIP like registration procedure and registers with the EGGSN where the UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and l-WLAN assigned IP address as the Co-CoA.
10. A method as claimed in claim 9 wherein the MIP like registration is done for FA-CoA where the MIP like registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN.
11. A method as claimed in claim 10 wherein for applications initiated by the UE in the l-WLAN, the UE uses the l-WLAN assigned IP address as the source IP address, and the UE directly contacts the correspondent node or alternatively, for the new applications initiated by the UE in the l-WLAN, the UE uses the

reverse tunneling.
12. A method as claimed in claim 11 wherein AAA uses the active keys provided by the EGGSN to derive the tunnel authentication keys and pass the said keys to the PDG for authentication where the AAA server includes the EGGSN IP address in the Access Accept message.
13. A method as claimed in claim 12 wherein AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains the new information about the UE in the HSS from the HSS before updating.
14. A method as claimed in claim 13 wherein the UE uses the AAA MIP registration procedure to do MIP registration during the IPsec tunnel establishment procedure where the MIP registration authenticator is generated from the active network access keys where the AAA forwards the MIP registration message to EGGSN and the EGGSN registers the UE and send the MIP ACK message to the UE via PDG.
15. A method as claimed in claim 14 wherein after successful authentication and tunnel establishment procedure, if UE is not capable of simultaneous access then AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE and if the UE is capable of simultaneous access then the UE starts EUMTS detach procedure.
16. A method as claimed in claim 15 wherein the PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA and if the EGGSN buffered the packets for the UE, then the EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE where if the UE is capable of simultaneous access, then the EGGSN starts bicasting the packets to both EUTRAN and l-WLAN access systems.
17. A method as claimed in claim 16 wherein after start receiving the packets from

the EGGSN, the UE does MIP based route optimization procedure with the CN, and if CN supports MIP and tunnel overhead is not considered to be disadvantage.
18. A method as claimed in claim 17 wherein if no active TCP connections were present, then the UE does SIP based terminal mobility procedure, and if it has any active IMS based sessions and avoids the MIP based mobility procedure the UE intimates the release of IP to the EGGSN in the HO confirm message.
19. A method as claimed in claim 18 wherein the HO complete message is sent within the IKEv2 or with any new signaling protocol and if MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol and the PDG relays the HO complete message to the EGGSN.
20. A method for providing mobility between interworking WLAN and EUTRAN access systems where handover from the l-WLAN to the EUTRAN access system involves the UE start scanning the other RAT and deciding to attach with the EUMTS AS based on the signal strength of l-WLAN or by other means.
21. A method as claimed in claim 20 wherein if the UE is not capable of simultaneous access, then the UE intimate the PDG to buffer the packets destined to the UE through a new IKEv2 notification payload or through a signalling message like MIP buffer management mechanism where optionally UE request the PDG to close the IPsec tunnel and resources reserved for the UE and the PDG starts buffering the packets destined to the UE.
22. A method as claimed in claim 21 wherein the UE establish L2/RRC connection with the EUMTS network and the UE sends the RAU message or alternatively any initial L3 message after the L2 connection, including the HO preparation message containing S-bit, l-WLAN ID, NAI and the PDG IP address where the user part of the NAI contains the IMSI or pseudonym or re-authentication id.

23. A method as claimed in claim 22 wherein EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the active AKA keys and also unused AVs from the AAA server where EGGSN updates the HSS about the new location of the UE.
24. A method as claimed in claim 23 wherein Optionally the HSS/AAA request the PDG to release the tunnel created for the UE, if UE is not capable of simultaneous access.
25. A method as claimed in claim 24 wherein EGGSN starts the integrity/ciphering using the active AKA keys and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request.
26. A method as claimed in claim 25 wherein EGGSN establish a tunnel with the PDG and if the S bit is off then EGGSN request the PDG to forward all the packets destined to the UE and the PDG tunnels the buffered packets to the EGGSN and then EGGSN forwards to the UE where if the S-bit is on, then the PDG starts bicasting the packets destined to the UE.
27. A method as claimed in claim 26 wherein after start receiving the packets through the EGGSN, if the UE is capable of simultaneous access, then the UE close the l-WLAN tunnel and the UE does MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage.
28. A method as claimed in claim 27 wherein if no active TCP connections are present, then the UE does SIP based terminal mobility procedure, and if UE has any active IMS based sessions and avoid the MIP based mobility procedure then the UE intimates the release of IP to the EGGSN in the HO confirm message where if MIP based solution is used then the UE just confirms the HO

by sending the HO complete message and the EGGSN relays the HO complete message to the PDG.
29. A system for providing mobility between interworking WLAN and EUTRAN access systems where handover from the EUTRAN to the l-WLAN access system involves a UE which sends periodic or event based measurements to the EUTRAN network wherein if the UE measurement is below the threshold or if EUMTS RAT cannot be continued, then EGGSN/ENB requests the UE to start scanning other RATs or alternatively by L2 or other means and UE decides that the EUTRAN cannot be continued and starts scanning the other RATs.
30. A system as claimed in claim 29 wherein the UE directly send the HO request to the AAA sever, through EGGSN and the packet is routed to the home AAA server by resolving the NAI where the HO request message contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN and alternatively the UE sends the measurements of l-WLAN to the EGGSN as requested by the EGGSN to scan other RATs.
H.A system as claimed in claim 29 wherein the said measurement includes the details of the l-WLAN like WLAN ID, NAI and W-APN/s formed by the UE according to the current ongoing applications.
i2. A system as claimed in claim 31 wherein EGGSN resolves IP addresses of the PDG using the W-APN(s) and the HO request is sent to AAA server using NAI where the HO request sent by the EGGSN contains the S-bit, NAI, RAT type, Authentication Vectors and EGGSN IP address included by the EGGSN.
3. A system as claimed in claim 32 wherein AAA verifies the NAI and stores the Authentication vectors and the EGGSN IP optional Address and the AAA server sends the HO accept message to the EGGSN where the AAA server assigns new IP address to the UE and include the IP address in the HO accept message where optionally, AAA server specify the PDG IP address in the HO accept

message, for the UE to establish the tunnel.
34. A system as claimed in claim 33 wherein the EGGSN sends the HO command to the UE and if the EGGSN resolves the PDG IP address/addresses, then the EGGSN includes the IP address/addresses in the HO command and where if the AAA server sends the IP address to the UE in the HO accept message, then the EGGSN includes the IP address in the HO command.
35. A system as claimed in claim 34 wherein if S-bit is off, then the EGGSN starts buffering the packets destined to the UE and if S-bit is on, the EGGSN does not buffer the data destined to the UE.
36. A system as claimed in claim 35 wherein after receiving the HO command, the UE starts the IKEv2 procedure to establish the IPsec tunnel towards the PDG and the UE selects the IP address of the PDG from the list provided by the EGGSN or UE and resolve the IP addresses of the PDGs where UE uses the active keys to derive the authentication keys and send the AUTH payload, to eliminate the EAP authentication procedure for IPsec tunnel establishment by UE.
37. A system as claimed in claim 36 wherein the UE performs the MIP registration procedure and registers with the EGGSN where the UE use the EUTRAN IP address as the HoA, PDG IP address as the CoA and l-WLAN assigned IP address as the Co-CoA.
38. A system as claimed in claim 37 wherein the MIP registration is done for FA-CoA where the MIP registration message is sent to the PDG by the UE and then it is forwarded by the PDG to the appropriate EGGSN.
39. A system as claimed in claim 38 wherein for applications initiated by the UE in the l-WLAN, the UE uses the l-WLAN assigned IP address as the source IP address, and the UE directly contacts the correspondent node or alternatively,

for the new applications initiated by the UE in the l-WLAN, the UE uses the reverse tunneling.
40. A system as claimed in claim 39 wherein AAA uses the active keys provided by the EGGSN to derive the tunnel authentication keys and pass the said keys to the PDG for authentication where the AAA server includes the EGGSN IP address in the Access Accept message.
41 .A system as claimed in claim 40 wherein AAA server stores the serving EGGSN IP address during the HO preparation procedure or alternatively AAA obtains the new information about the UE in the HSS from the HSS before updating.
42. A system as claimed in claim 41 wherein the UE uses the AAA MIP registration procedure to do MIP registration during the IPsec tunnel establishment procedure where the MIP registration authenticator is generated from the active network access keys where the AAA forwards the MIP registration message to EGGSN and the EGGSN registers the UE and send the MIP ACK message to the UE via PDG.
43. A system as claimed in claim 42 wherein after successful authentication and tunnel establishment procedure, if UE is not capable of simultaneous access then AAA/HSS triggers the EGGSN to release the radio resources allocated to the UE and if the UE is capable of simultaneous access then the UE starts EUMTS detach procedure.
44. A system as claimed in claim 43 wherein the PDG establish a tunnel towards the EGGSN as like tunnel between HA and FA and if the EGGSN buffered the packets for the UE, then the EGGSN tunnels the buffered packets to the PDG and the PDG forwards the packets to the UE where if the UE is capable of simultaneous access, then the EGGSN starts bicasting the packets to both EUTRAN and l-WLAN access systems.

45. A system as claimed in claim 44 wherein after start receiving the packets from the EGGSN, the UE does MIP based route optimization procedure with the CN, and if CN supports MIP and tunnel overhead is not considered to be disadvantage.
46. A system as claimed in claim 45 wherein if no active TCP connections were present, then the UE does SIP based terminal mobility procedure, and if it has any active IMS based sessions and avoids the MIP based mobility procedure the UE intimates the release of IP to the EGGSN in the HO confirm message.
47. A system as claimed in claim 46 wherein the HO complete message is sent within the IKEv2 or with any new signaling protocol and if MIP based solution is used then the UE just confirms the HO by sending the HO complete message within the IKEv2 or with any new signaling protocol and the PDG relays the HO complete message to the EGGSN.
48. A system for providing mobility between interworking WLAN and EUTRAN access systems where handover from the l-WLAN to the EUTRAN access system involves the UE start scanning the other RAT and deciding to attach with the EUMTS AS based on the signal strength of l-WLAN or by other means.
49.A system as claimed in claim 48 wherein if the UE is not capable of simultaneous access, then the UE intimate the PDG to buffer the packets destined to the UE through a new IKEv2 notification payload or through a signalling message like MIP buffer management mechanism where optionally UE request the PDG to close the IPsec tunnel and resources reserved for the UE and the PDG starts buffering the packets destined to the UE.
50. A system as claimed in claim 49 wherein the UE establish L2/RRC connection with the EUMTS network and the UE sends the RAU message or alternatively any initial L3 message after the L2 connection, including the HO preparation message containing S-bit, l-WLAN ID, NAI and the PDG IP address where the

user part of the NAI contains the IMSI or pseudonym or re-authentication id.
51. A system as claimed in claim 50 wherein EGGSN, with the NAI resolves the AAA server serving the UE and retrieves the active AKA keys and also unused AVs from the AAA server where EGGSN updates the HSS about the new location of the UE.
52. A system as claimed in claim 51 wherein Optionally the HSS/AAA request the PDG to release the tunnel created for the UE, if UE is not capable of simultaneous access.
53. A system as claimed in claim 52 wherein EGGSN starts the integrity/ciphering using the active AKA keys and provides the temporary identities, IP address and KSI to the UE in the RAU accept message or alternatively in the response message to the initial L3 request.
54. A system as claimed in claim 53 wherein EGGSN establish a tunnel with the PDG and if the S bit is off then EGGSN request the PDG to forward all the packets destined to the UE and the PDG tunnels the buffered packets to the EGGSN and then EGGSN forwards to the UE where if the S-bit is on, then the PDG starts bicasting the packets destined to the UE.
55. A system as claimed in claim 54 wherein after start receiving the packets through the EGGSN, if the UE is capable of simultaneous access, then the UE close the l-WLAN tunnel and the UE does MIP based route optimization procedure with the CN, if CN supports MIP and tunnel overhead is not considered to be disadvantage.
56. A system as claimed in claim 55 wherein if no active TCP connections are present, then the UE does SIP based terminal mobility procedure, and if UE has any active IMS based sessions and avoid the MIP based mobility procedure then the UE intimates the release of IP to the EGGSN in the HO confirm

message where if MIP based solution is used then the UE just confirms the HO by sending the HO complete message and the EGGSN relays the HO complete message to the PDG.
57. A system as claimed in claim 1 wherein the said method includes solutions for
the UE.which is capable of simultaneous and non-simultaneous access.
58. A system as claimed in claim 1 wherein the said method includes to provide signaling interface between the EGGSN and the AAA server to exchange messages between them.
59. A system as claimed in claim 1 wherein the said method includes to send the IP address of the EGGSN stored by the AAA server to the PDG during the tunnel establishment procedure. Using the EGGSN IP address, PDG contacts the serving EGGSN to retrieve the buffered packet at the EGGSN destined to the UE.
60. A method for providing mobility between interworking WLAN and EUTRAN
access systems substantially described particularly with reference to the
accompanying drawings.
61. A system for providing mobility between interworking WLAN and EUTRAN
access systems substantially described particularly with reference to the
accompanying drawings.

Documents:

1562-che-2005 abstract granted.pdf

1562-che-2005 claims granted.pdf

1562-che-2005 description (complete) granted.pdf

1562-che-2005 drawings granted.pdf

1562-che-2005-abstract.pdf

1562-che-2005-claims.pdf

1562-che-2005-correspondnece-others.pdf

1562-che-2005-correspondnece-po.pdf

1562-che-2005-description(complete).pdf

1562-che-2005-drawings.pdf

1562-che-2005-form 1.pdf

1562-che-2005-form 26.pdf

1562-che-2005-form9.pdf

« Previous Patent

Next Patent »

Patent Number

228601

Indian Patent Application Number

1562/CHE/2005

PG Journal Number

12/2009

Publication Date

20-Mar-2009

Grant Date

05-Feb-2009

Date of Filing

27-Oct-2005

Name of Patentee

SAMSUNG INDIA SOFTWARE OPERATIONS PRIVATE LIMITED

Applicant Address

BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,

Inventors:

#	Inventor's Name	Inventor's Address
1	R. RAJAVELSAMY	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,
2	JEEDIGUNTA VENKATESWAR	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,
3	RAHUL SUHAS VAIDYA	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,
4	SUNGHO CHOI	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,
5	OSOK SONG	BAGMANE LAKEVIEW, BLOCK 'B', NO. 66/1, BAGMANE TECH PARK, C V RAMAN NAGAR, BYRASANDRA, BANGALORE 560 093,

PCT International Classification Number

H04L12/28

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA