Abstract:
A method and apparatus for optimizing mobility management procedures comprises establishing a tunnel between a wireless transmit/receive unit (WTRU) and a target system core network (CN). The WTRU is handed over from a source system CN system to the target system CN.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional application No. 60/948,556, filed Jul. 9, 2007 and U.S. provisional application No. 60/949,086, filed Jul. 11, 2007, which are incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention is related to wireless communication systems. 
       BACKGROUND 
       [0003]    A dual-mode or multi-mode wireless transmit/receive unit has dual or multiple radio transceivers, each designed to communicate on a particular radio access technology (RAT), such as 3 rd  Generation Partnership Project (3GPP) and non-3GPP systems. The handover process between 3GPP and non-3GPP systems may be slow due to the nature of the system configurations and operations. One problem occurs when a WTRU moves from one system to another as the WTRU is required to register and authenticate in the other system. A similar problem exists for session initiation protocol (SIP)-based Session Continuity processes between 3GPP and non-3GPP systems. When moving from one system to the other, the WTRU is required to register and authenticate in the other system before registering with internet protocol (IP) multimedia subsystem (IMS). 
         [0004]    Another problem may occur due to the 3GPP prohibition against simultaneous radio transceiver operation. A single WTRU cannot have a 3GPP radio transceiver and a non-3GPP radio transceiver active at the same time. In such cases, dual-mode or multi-mode radio transceivers need sophisticated control of the radio switching. 
         [0005]    It would therefore be beneficial to provide an improved method and apparatus for handover. 
       SUMMARY 
       [0006]    A method and apparatus are disclosed to optimize mobility management procedures using pre-registration tunneling. The method and apparatus comprise establishing a tunnel between a wireless transmit/receive unit (WTRU) and a target system core network (CN). The WTRU is handed over from a source system CN system to the target system CN. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
           [0008]      FIG. 1  is a block diagram of dual stack operation in a multi-mode WTRU in accordance with one embodiment of the present invention; 
           [0009]      FIG. 2  is a block diagram of dual stack operation in a multi-mode WTRU for SIP based continuity in 3GPP to non-3GPP handover in accordance with the present invention; 
           [0010]      FIG. 3  is a block diagram of dual stack operation in a multi-mode WTRU for SIP based continuity in non-3GPP to 3GPP handover in accordance with the present invention; 
           [0011]      FIGS. 4A and 4B  are a signal diagram of pre-registration and preauthentication for 3GPP to non-3GPP handover in accordance with the disclosed method; 
           [0012]      FIGS. 5A and 5B  are a signal diagram of pre-registration and preauthentication for 3GPP to non-3GPP handover in accordance with the disclosed method; 
           [0013]      FIGS. 6A ,  6 B and  6 C are a signal diagram of pre-registration for 3GPP to non-3GPP handover in accordance with the present invention; and 
           [0014]      FIGS. 7A ,  7 B and  7 C are a signal diagram of pre-registration for a non-3GPP to 3GPP handover in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    When referred to hereafter, the terminology “wireless transmit/receive unit (WTRU)” includes but is not limited to a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. When referred to hereafter, the terminology “base station” includes but is not limited to a Node-B, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment. 
         [0016]    By way of reference, as a WTRU moves from a system A to a system B, system A is defined as the source system and system B is defined as the target system. In accordance with a disclosed method, to speed access procedures to a target system, pre-registration and pre-authentication procedures are performed by higher layers in a WTRU via the source system. This may include IP configuration and SIP registration procedures. In accordance with the disclosed method, the source system identifies the target system, establishes a tunnel between the terminal and the core network (e.g., Autonomous Registration (AR) or Access, Authentication and Accounting (AAA)) of the target system (3GPP2, WiMAX or WiFi, for example), and instructs the WTRU to start access procedures for the target system, such as attach, IP configuration or SIP registration. Upon successful completion of the access procedure and the SIP registration, the source system then instructs the WTRU to switch, or handover, to the target system and turn off the radio connected to the source system. 
         [0017]      FIG. 1  is a block diagram of a dual stack operation in a multi-mode WTRU  20 . As shown in  FIG. 1 , WTRU  20  comprises a first transceiver  22  and a second transceiver  24 . The first and second transceivers  22  and  24 , respectively, communicate within a certain network type. A network type may be one of any 3GPP or non-3GPP networks. For purposes of this disclosure, first transceiver  22  is a 3GPP transceiver and second transceiver  24  is a non-3GPP transceiver. 
         [0018]    3GPP transceiver  22  and non-3GPP transceiver  24  each include a plurality of layers for processing received and transmitted wireless communications. 3GPP transceiver  22  comprises a physical layer  201  (Layer 1) coupled to a 3GPP radio resource control (RRC) and medium access control (MAC) layer  210  (Layer 2). RRC Layer  210 , is coupled to Physical Layer  201 , a 3GPP mobility management (MM) and session management (SM) layer  220  (Layer 3) and a non-3GPP SM and MM layer  221 , to be disclosed hereinafter. 3GPP MM Layer  220  is coupled to RRC Layer  210  and an application layer (e.g., a session initiation protocol (SIP))  230  (Layer 4), and a non-3GPP RRC and MAC layer  211 , to be disclosed hereinafter. 3GPP Application Layer  230  is coupled to MM Layer  220 . 
         [0019]    Non-3GPP transceiver  24 , similar to 3GPP transceiver  22 , comprises a non-3GPP physical layer  201  coupled to a non-3GPP RRC  211 . RRC Layer  211  is coupled to Physical Layer  202  and non-3GPP MM layer  221  and 3GPP MM layer  220 . Non-3GPP MM layer  221  is coupled to non-RRC Layer  211  and non-3GPP application layer  231  and 3GPP RRC Layer  210 . Non-3GPP Application  231  is coupled to MM Layer  221 . 
         [0020]    In order to accommodate communications by WTRU  20  in 3GPP and non-3GPP systems, in accordance with this disclosed method, 3GPP RRC Layer  210  is in direct communication with non-3GPP MM Layer  221 . Likewise, non-3GPP RRC Layer  211  is in direct communication with 3GPP MM Layer  220 . 
         [0021]      FIG. 2  shows a block diagram of dual stack operation in a multi-mode WTRU  200  for pre-registration, IP configuration and SIP based continuity in 3GPP to non-3GPP handover. Initially, a multi-mode WTRU  200  is communicating on a 3GPP network, through the internal 3GPP layers  201 ,  210 ,  220  and  230  in WTRU  200  to a 3GPP e-node B (eNB)  340 , then to a 3GPP core network (CN)  330  and to the IP multimedia subsystem (IMS)  310  (Path  1 ). 
         [0022]    During a handover from the 3GPP network to a non-3GPP network, non-3GPP radio transceiver  24  communicates with IMS  310  through 3GPP radio transceiver  250 , in accordance with the disclosed method. As such, a communication is sent from non-3GPP Layer 4  231  to Layer 3  221  to non-3GPP Layer 2  211 . Non-3GPP Layer 2  211  then forwards the communication to 3GPP Layer 3  220 . Layer 3GPP  220  forwards the communication through the 3GPP Layer 2  210  and Layer 1  201  layers, then to 3GPP eNB  340  and 3GPP CN  330 . 3GPP CN  330  then communicates directly with non-3GPP CN  360  that communicates with IMS  210  through a gateway  320  (Path  2 ). Once handover is complete, WTRU  200  communicates with IMS  310  through non-3GPP radio transceiver  240 , a non-3GPP radio access network (RAN)  350 , non-3GPP CN  360  and gateway  320  (Path  3 ). 
         [0023]      FIG. 3  shows a block diagram of dual stack operation in a multi-mode WTRU for pre-registration, IP configuration and SIP based continuity in non-3GPP to 3GPP handover. Initially, a multi-mode WTRU  400  is communicating on a non-3GPP network through a non-3GPP radio transceiver  411 , including internal non-3GPP layers  408 ,  406 ,  404  and  402  in WTRU  400 , to non-3GPP RAN  450 , to non-3GPP CN  460  then to IMS  410  through a gateway  420  (Path  1 ). During a handover from the non-3GPP network to a 3GPP network, 3GPP radio transceiver  412  communicates with IMS  410  initially through non-3GPP radio transceiver  411 . A communication from 3GPP radio transceiver  412  is sent from 3GPP Layers  4  or to 3GPP Layer 3  405  to 3GPP Layer 2  403 . Layer 3  403  forwards the communication to non-3GPP Layer 3  406 , which then forwards the communication to non-3GPP Layer 3  406 , which then forwards the communication to non-3GPP RAN  450  through non-3GPP Layer 2  404  and Layer 1  402 . Non-3GPP RAN  450  forwards the communication to non-3GPP CN  430  then forwards the communication to IMS  410  (Path  2 ). Once handover is complete, WTRU  400  communicates with the IMS through the 3GPP radio transceiver  412  including 3GPP Layer 4  405 ,  406 ,  403  and  401 , 3GPP eNB  440  and 3GPP CN  430  (Path  3 ). 
         [0024]      FIG. 4A and 4B  are a signal diagram for pre-registration procedure for a handover of a WTRU  30  from a 3GPP handover source  33  to a non-3GPP handover target  34 . A WTRU  30  includes a 3GPP radio transceiver  31  and a non-3GPP radio transceiver  32  for communication with a 3GPP core network (CN)  33  and a non-3GPP CN  34 . For simplicity, a dual mode WTRU  30  is shown, however the signaling described herein is valid for a multi-mode WTRU having multiple 3GPP and non-3GPP radio transceivers. While shown as direct signals from WTRU  30  and CNs  33 ,  34 , the signals may be relayed by a NodeB or a base station radio transceiver (not shown). 
         [0025]    Pre-registration begins with 3GPP transceiver  31  receiving a 3GPP and non-3GPP measurement list  100  from 3GPP CN  33 . The measurement list ( 100 ) identifies the channel frequencies of candidate handover targets. WTRU  30  stores the list in an internal memory, and for periodically initiating channel measurements ( 101 ). 3GPP transceiver  31  sends an initialization signal ( 102 ) to non-3GPP transceiver  33 , along with a list of candidate non-3GPP handover targets ( 103 ). Non-3GPP transceiver  32  is activated for a period in order to perform measurement procedures, in which it monitors channels and performs measurements ( 104 ). Non-3GPP transceiver  32  sends measurement reports ( 105 ) of the monitored channels to 3GPP transceiver  31 . When measurement procedures by non-3GPP transceiver  32  are completed, it may be deactivated. 
         [0026]    3GPP transceiver  31  combines the measurements it made with those made by non-3GPP transceiver  32 , formulates combined measurement reports, and transmits the combined measurement reports ( 106 ) to the 3GPP CN  33 . 3GPP CN  33  examines the combined measurement reports and selects a handover target system ( 107 ) for WTRU  30 . 3GPP CN  33  then sends a signal to target non-3GPP CN  34  to initiate a handover direct tunnel ( 108 ), and target non-3GPP CN  34  responds with a tunnel establishment acknowledgment signal ( 109 ). 3GPP CN  33  sends a signal to 3GPP transceiver  31  to initiate a handover direct tunnel ( 110 ). This signal ( 110 ) may include a non-3GPP tunnel endpoint identification (TEID). 3GPP transceiver  31  sends the target ID ( 111 ) to non-3GPP transceiver  32 . Non-3GPP transceiver  32  sends its handover direct tunnel acknowledgment (ACK)  112  to 3GPP transceiver  31 , which is then forwarded to 3GPP CN  33  as signal  113 . The direct handover tunnel  114  is established between non-3GPP target CN  34  and non-3GPP transceiver  32 . Source 3GPP CN  33  sends a signal to initiate a non-3GPP registration ( 115 ) to 3GPP transceiver  31  which is then forwarded as signal ( 116 ) to non-3GPP transceiver  32 . The upper layers of non-3GPP transceiver  32  perform pre-registration pre-authentication procedures, and send a non-3GPP registration request ( 117 ), ( 118 ) via 3GPP transceiver  31  to non-3GPP target CN  34 . 
         [0027]    3GPP radio transceiver  32  and non-3GPP target CN  34  then conduct authentication procedures ( 119 ). Handover triggers ( 120 ) are communicated directly between 3GPP CN  33  and non-3GPP CN  34  and the 3GPP CN  33  initiates handover with a signal ( 121 ) to 3GPP transceiver  31 . 3GPP transceiver  31  instructs non-3GPP radio transceiver  32  to turn ON as signal ( 122 ). With non-3GPP radio transceiver  32  turned ON, it makes initial contact with non-3GPP CN  34  and commences radio contact procedures ( 123 ). 3GPP radio transceiver  31  is turned OFF ( 124 ) and 3GPP CN  33  and non-3GPP CN  34  exchange handover complete and tunnel release signals ( 125 ). 
         [0028]      FIG. 5A and 5B  are a signal diagram for pre-registration procedure for a handover of a WTRU  30  from a non-3GPP source  33  to a 3GPP  34 . WTRU  30  includes a non-3GPP transceiver  31  and a 3GPP radio transceiver  32  for communication with non-3GPP CN  33  and 3GPP CN  34 . 
         [0029]    Pre-registration begins with non-3GPP transceiver  31  receiving a 3GPP and non-3GPP measurement list ( 130 ) from non-3GPP CN  33 . Measurement list ( 130 ) identifies the channel frequencies of candidate handover targets. WTRU  30  stores the list in an internal memory, and for periodically initiating channel measurements ( 131 ). Non-3GPP transceiver  31  sends an initialization signal ( 132 ) to 3GPP transceiver  32 , along with a list of candidate 3GPP handover targets ( 133 ). 3GPP transceiver  32  is activated and monitors channels and performs measurements ( 134 ). 
         [0030]    3GPP transceiver  32  sends measurement reports ( 135 ) of the monitored channels to non-3GPP transceiver  31 . Non-3GPP transceiver  31  combines the measurements it made with those made by 3GPP transceiver  32 , formulates combined measurement reports, and transmits the combined measurement reports ( 136 ) to non-3GPP CN  33 . Non-3GPP CN  33  examines the combined measurement reports and selects a handover target system ( 137 ) for WTRU  30 . Non-3GPP CN  33  sends a signal  34  to target 3GPP CN  34  to initiate a handover direct tunnel ( 138 ), and target 3GPP CN  34  responds with a tunnel establishment acknowledgment signal ( 139 ). 3GPP non-CN  33  sends a signal to non-3GPP transceiver  31  to initiate a handover direct tunnel ( 140 ). Signal  140  may include a 3GPP tunnel endpoint identification (TEID). Non-3GPP transceiver  31  sends the target ID ( 141 ) to the 3GPP transceiver  32 . 3GPP transceiver  32  sends its handover direct tunnel acknowledgment (ACK) ( 142 ) to non-3GPP transceiver  31 , which is then forwarded to non-3GPP CN  33  as signal ( 143 ). The direct handover tunnel ( 144 ) is established between 3GPP target CN  34  and 3GPP transceiver  32 . Source non-3GPP CN  33  sends a signal to initiate a 3GPP registration ( 145 ) to non-3GPP transceiver  31 , which is then forwarded as signal ( 146 ) to 3GPP transceiver  32 . A 3GPP registration request ( 147 ,  148 ) is sent from 3GPP transceiver  32  via non-3GPP transceiver  31  to 3GPP target CN  34 . 
         [0031]    Non-3GPP radio transceiver  31  and 3GPP target CN  34  then conduct authentication procedures ( 149 ). Handover triggers ( 150 ) are communicated directly between non-3GPP CN  33  and 3GPP CN  34 , and non-3GPP CN  33  initiates handover with a signal ( 151 ) to non-3GPP transceiver  31 . Non-3GPP transceiver  31  instructs non-3GPP radio transceiver  32  to turn ON with signal ( 152 ). With 3GPP radio transceiver  32  turned ON, it makes initial contact with the 3GPP CN  34  and commences radio contact procedures ( 153 ). Non-3GPP radio transceiver  31  is turned OFF ( 154 ) and non-3GPP CN  33  and 3GPP CN  34  exchange handover complete and tunnel release signals ( 158 ). 
         [0032]      FIGS. 6A ,  6 B and  6 C are a signal diagram for 3GPP to non-3GPP pre-registration. A WTRU  500  includes a 3GPP radio transceiver  501  and a non-3GPP radio transceiver  502 . There is a SIP connection ( 550 ) between 3GPP radio transceiver  501  in WTRU  500  and a 3GPP CN  510 , and from 3GPP CN  510  to an IMS  530 . The 3GPP CN  510  transmits a 3GPP and non-3GPP measurement list ( 551 ) to WTRU  500 . WTRU  500  receives the frequency list and stores the list in internal memory ( 552 ). WTRU  500  may then periodically initiate channel measurements. 
         [0033]    3GPP radio transceiver  501  in WTRU  500  may then initialize non-3GPP radio transceiver  502  ( 553 ) and send non-3GPP radio transceiver  502  a list of non-3GPP targets ( 554 ). In turn, non-3GPP radio transceiver  502  may monitor channels and perform measurements ( 555 ). The measurement reports can then be sent to 3GPP radio transceiver  501  ( 556 ), which then transmit all measurement reports to 3GPP CN  510  ( 557 ). 
         [0034]    3GPP CN  510  examines the measurement report and handover criteria ( 558 ) which may be used to decide on the target system. Once 3GPP CN  510  has decided on the target system, a handover direct tunnel to the targeted non-3GPP CN  520  is initiated ( 559 ). 
         [0035]    After receiving a tunnel establishment acknowledge message ( 560 ) from non-3GPP network  520 , 3GPP CN  510  then initiates a direct handover tunnel ( 561 ) with non-3GPP radio transceiver  502  in WTRU  500  through 3GPP radio transceiver  501  ( 562 ). The handover tunnel preferably is acknowledged by non-3GPP radio transceiver  502  ( 563 ) to 3GPP CN  501  ( 564 ) and the handover tunnel established. 
         [0036]    Once the tunnel is established, 3GPP CN  510  initiates non-3GPP registration. Non-3GPP radio transceiver  502  sends a registration request ( 572 ) to non-3GPP CN  520  through 3GPP radio transceiver  501  ( 573 ). In the request ( 573 ), the tunnel endpoint identifier (TEID) is related to non-3GPP CN  520 . 3GPP radio transceiver  501 , along with non-3GPP CN  520 , then conducts authentication procedures ( 574 ,  575 ). 
         [0037]    Preferably, the IP configuration procedures ( 580 ) between WTRU  500  and non-3GPP CN  520  are now started ( 581 ). Once the IP configuration is complete ( 582 ), SIP registration is started ( 590 ,  591 ). Once SIP registration is complete ( 593 ), there may be SIP connectivity directly between the 3GPP and non-3GPP CNs ( 592 ). 3GPP CN  510  may then instruct WTRU  500  ( 591 ) to handover to non-3GPP CN  520 . The non-3GPP radio transceiver  502  in WTRU  500  is turned on and contacts non-3GPP CN  520  ( 594 ) 3GPP radio transceiver  501  is turned off, and handover is completed ( 596 ) and the tunnel released ( 598 ). 
         [0038]      FIGS. 7A ,  7 B and  7 C are a signal diagram for a non-3GPP to 3GPP pre-registration. A WTRU  600  includes a 3GPP radio transceiver  601  and a non-3GPP radio transceiver  602 . There is a SIP connection between the non-3GPP radio transceiver  601  in WTRU  600  and a non-3GPP CN  620 , and from non-3GPP CN  630  to an IMS  630 . Non-3GPP CN  620  may transmit a 3GPP and non-3GPP measurement list ( 641 ) to WTRU  600 . WTRU  600  can receive the frequency list and store the list in internal memory ( 642 ). WTRU  600  may then periodically initiate channel measurements. 
         [0039]    Non-3GPP  602  radio in WTRU  600  may then initialize 3GPP radio  601  ( 643 ) and send the 3GPP radio  601  a list of 3GPP targets ( 644 ). In turn, 3GPP radio  601  may monitor channels and perform measurements ( 645 ). The measurement reports can be sent to the non-3GPP radio ( 646 ), which then transmits all measurement reports to non-3GPP CN  620  ( 647 ). 
         [0040]    Non-3GPP CN  620  preferably examines the measurement report and handover criteria, then decides on the target system ( 648 ) and initiates a handover direct tunnel to the targeted 3GPP system  610  ( 649 ). 
         [0041]    After receiving a tunnel establishment acknowledge message ( 650 ) from 3GPP network  610 , non-3GPP CN  620  may initiate a direct handover tunnel with the 3GPP radio transceiver  601  in WTRU  600  ( 651 ) through the non-3GPP radio transceiver  602  ( 652 ). The handover tunnel preferably is acknowledged by the 3GPP radio transceiver  601  ( 653 ) through non-3GPP radio transceiver  602  ( 654 ), and the handover tunnel  655  is established. 
         [0042]    Once the tunnel is established, non-3GPP CN  620  may initiate 3GPP registration with 3GPP radio  601  through non-3GPP radio  602 ( 660 , 661 ). 3GPP radio transceiver  601  sends a registration request  663  to 3GPP CN  610  through non-3GPP transceiver  602  ( 662 ). In request ( 662 ,  663 ), the tunnel endpoint identifier (TEID) is related to non-3GPP CN  620 . 3GPP radio transceiver  601  in WTRU  600  along with 3GPP CN  610 , conduct authentication procedures ( 664 ,  665 ). 
         [0043]    The 3GPP IP configuration is then started ( 670 ) and the IP configuration procedures between WTRU  600  and 3GPP CN  620  are conducted ( 671 , 672 ). Once the IP configuration is complete ( 673 ), SIP registration is started ( 680 ). 3GPP transceiver  602  requests SIP registration through non-3GPP transceiver  602  ( 681 ), which communicates this to non-3GPP CN  620  ( 683 ), which then communicates with IMS  630  ( 684 ). SIP registration information is then sent to 3GPP transceiver  601  along the same signal path ( 684 ,  683 ,  632 ,  631 ). Once SIP registration is complete  685 , there is SIP connectivity between 3GPP radio transceiver  601  and 3GPP CN  610  ( 686 ) and between 3GPP CN  620  and IMS  630  ( 687 ). 
         [0044]    Handover is completed to 3GPP CN  610  ( 688 ), SIP de-registration and IP release procedures are then performed between non-3GPP transceiver  602  and IMS  630  ( 689 ), handover to 3GPP CN  610  is completed and the non-3GPP radio bearer is released ( 690 ,  691 ). 3GPP radio transceiver  601  may then complete connection to 3GPP CN  610  ( 692 ) with no interruption in SIP and IMS operation. 
         [0045]    Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). 
         [0046]    Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine. 
         [0047]    A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB) module.