Abstract:
A method and apparatus for implementing an attachment procedure in multi-mode systems are disclosed. A wireless communication system includes at least one of a second generation (2G) system, a third generation (3G) system, a long term evolution (LTE) and system architecture evolution (SAE) of the 3G system and a non-3G system. For performing an attachment procedure, a wireless transmit/receive unit (WTRU) sends an attach request message to a new serving general packet radio service (GPRS) support node (SGSN) indicating an attach type. The new SGSN and the WTRU then perform an attachment procedure based on the attach type. The attach type may indicate a GPRS only attachment, a GPRS and SAE attachment, or a 3GPP and non-3GPP attachment.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/887,368 filed Jan. 31, 2007, which is incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    This application is related to wireless communications. 
       BACKGROUND 
       [0003]    Long term evolution (LTE) and system architecture evolution (SAE) of a third generation (3G) wireless communication system are being developed to provide higher data rates, lower latency, and support of multiple radio access technologies (RATs). The main features of the LTE include an enhanced air interface to handle higher data rates with more efficiency, optimization of conventional procedures to reduce the number of signaling procedures and reduce setup delay, and network design to permit interconnection and interoperation of any air interface, such as global system for mobile communications (GSM), general packet radio service (GPRS), wideband code division multiple access (WCDMA), code division multiple access 2000 (CDMA 2000), IEEE 802.xx, and the like. 
       SUMMARY 
       [0004]    A method and apparatus for performing attachment procedures are disclosed. The attachment procedures are performed in a multi-mode wireless communication system including at least one of a second generation (2G) system, a 3G system, an LTE and SAE of the 3G system and a non-3G system. A wireless transmit/receive unit (WTRU) sends an attach request message to a new serving GPRS support node (SGSN) indicating an attach type. The new SGSN and the WTRU then perform an attachment procedure based on the attach type. The attach type may indicate a GPRS only attachment, a GPRS and SAE attachment, or third generation partnership project (3GPP) and non-3GPP attachment. 
         [0005]    The new architecture disclosed herein allows for multiple mobility management for a data session at the core network and the interworking between a 3GPP network and other networks, (e.g., CDMA 2000, worldwide interoperability for microwave access (WiMAX), and the like). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0006]    A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
           [0007]      FIG. 1  is a signaling diagram of a simplified attachment procedure; 
           [0008]      FIGS. 2A-2D , taken together, are a signaling diagram of an attachment procedure implemented during a handover; 
           [0009]      FIG. 3  is a block diagram of a WTRU used to perform the attachment procedures of  FIGS. 2A-2D ; 
           [0010]      FIG. 4  is a block diagram of an SGSN/mobility management entity (MME) used to perform the attachment procedures of  FIGS. 2A-2D ; 
           [0011]      FIG. 5  is a block diagram of a gateway GPRS support node (GGSN)/3G access gateway (aGW) used to perform the attachment procedures of  FIGS. 2A-2D ; and 
           [0012]      FIG. 6  is a block diagram of an SAE aGW used to perform the attachment procedures of  FIGS. 2A-2D . 
       
    
    
     DETAILED DESCRIPTION  
       [0013]    When referred to hereafter, the terminology “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. 
         [0014]      FIG. 1  is a signaling diagram of a simplified attachment procedure  150  implemented in a wireless communication system  100  including a WTRU  105 , a radio access network (RAN)  110 , a SGSN/MME  115 , a GGSN/3G aGW  120 , an SAE aGW  125  and a policy and charging rules function (PCRF) unit  130 . Upon power up, the WTRU  105  establishes an initial access to an evolved Node-B (eNB) in the RAN  110 , (i.e., 2G, 3G or LTE RAN) (step  152 ). The WTRU  105 , the RAN  110  and the SSGN/MME  115  perform combined attachment procedures (step  154 ). For the various combined attachment procedures presented in  FIG. 1 , the extent of registration process, (i.e., GPRS only, GPRS and LTE/SAE only, and 3GPP and non-3GPP), is indicated. 
         [0015]    The SGSN/MME  115  is configured to determine the type of registration by examining an information element (IE) included in the attach request message received from the WTRU  105 . A legacy message format will identify the “GPRS only” registration. An SAE registration will be marked by the IE indicating the capability of the WTRU  105  as an SAE WTRU or an LTE WTRU. In the case of non-3GPP support, the WTRU  105  will indicate the type of mobility management required to support non-3GPP systems, (i.e., GPRS tunneling protocol (GTP) or mobile Internet protocol (MIP)). For MIP, the WTRU  105  indicates whether MIPv4, proxy MIP, or MIPv6 is being implemented. This may be either conveyed by indicating the IP version that is supported. For MIPv6, the WTRU  105  will indicate dual stack IPv6 support. In case of IPv4, the network may be configured to support proxy MIP. 
         [0016]    In case of GPRS only, in response to an initial attach, the SGSN/MME  115  will send an attachment accept message (without the allocated IP address) to the WTRU  105 . In case of the SAE, the GGSN/3G aGW  120  will send the attachment accept message to the SGSN/MME  115 , which will forward it to the WTRU  105 . This attachment accept message will include the IP address and the type of IP protocol (v4 or v6). In case of SAE and non-3GPP, the attachment accept message will indicate the successful home agent (HA) registration process so that the MIP client in the WTRU  105  is initiated. This is in response to the initial attach request message sent by the WTRU  105 , which indicates which mobility management it supports for interworking with non-3GPP systems, (i.e., 3GPP GTP, MIP (v4, v6). 
         [0017]    If the registration is for GPRS only, the attachment procedure is performed between the WTRU  105  and the SGSN/MME  115 . Once attachment is established, an attachment accept message is sent (step  156 ). 
         [0018]    If the registration is for 3GPP SAE/LTE, a GTP-U tunnel is established between a GPRS gateway support node (GGSN)/3G access gateway (aGW) and an eNB of the RAN (step  158 ). Once an attachment is established, an attachment accept message is sent (step  160 ). 
         [0019]    If the registration is for 3GPP SAE/LTE and non-3GPP access, the attachment procedure for the SAE non-3GPP and policy and charging rules function (PCRF) is performed at step  162 , (e.g., for establishment of mobile Internet protocol (MIP) home agent (HA), MIP registration, or the like). Once attachment is established, an attachment accept message is sent at step  164 . 
         [0020]      FIG. 2A  is a signaling diagram of a simplified attachment procedure  250  implemented in a wireless communication system  200  including a WTRU  205 , a RAN  210 , a new SGSN/MME  215 , an old SGSN/MME  220 , a GGSN/3G aGW  225 , an SAE aGW  230 , a new visited location register (VLR)  235 , a home location register (HLR)  240  and an old VLR  245 . The WTRU  205  initiates the attach procedure by the transmission of an attach request message to the new SGSN/MME  215  (step  252 ). The attach request message includes an international mobile subscriber identity (IMSI), an attach type, or the like (step  254 ). Alternatively, instead of sending the IMSI, the attach request message may include a packet-temporary mobile subscriber identity (P-TMSI) and an old routing area identity (RAI). The attach type indicates the attachment type, such as 2G, 3G or SAE multimode attachment. 
         [0021]    If the WTRU  205  identifies itself with the P-TMSI, the new SGSN/MME  215  derives an old SGSN address from the RAI to request IMSI information of the WTRU  205  (step  256 ). The new SGSN/MME  215  sends an identification request message to the old SGSN/MME  220  (step  258 ). The identification request message includes a P-TMSI, an old RAI, old P-TMSI signature, and the like. The old SGSN/MME  220  checks the P-TMSI against a record (step  260 ), and sends an identification response message with the IMSI of the WTRU  205  to the new SGSN/MME (step  262 ). If the WTRU  205  is known in the old SGSN/MME  220 , the old SGSN/MME  220  responds with an identification response message including the IMSI, authentication triplets or authentication quintets in step  262 . If the WTRU  205  is not known in the old SGSN/MME  220  or the old P-TMSI does not match the value stored in the old SGSN/MME  220 , the old SGSN/MME  220  responds with an appropriate error indication in the identification response message at step  262 . 
         [0022]    If the WTRU  205  is unknown in the new SGSN/MME  215  and the old SGSN/MME  220  (step  264 ), the new SGSN/MME  215  sends an identity (ID) request (setting an ID type to IMSI) to the WTRU  205  (step  266 ). The WTRU  205  responds with an ID response including the IMSI of the WTRU  205  (step  268 ). 
         [0023]    If no multi-mode (MM) context for the WTRU is evident (step  270 ), an authentication procedure is performed by the WTRU, the new SGSN/MME  215  and the HLR  240  (steps  272 A and  272 B). 
         [0024]    Referring to  FIG. 2B , an attachment procedure  350  for GPRS only is presented in further detail. Based on operator configuration (step  352 ), an international mobile equipment identity (IMEI) checking procedure may optionally be performed by the WTRU  205 , the new SGSN/MME  215  and the GGSN/3G aGW  225  (steps  354 A and  354 B). 
         [0025]    If the SGSN/MME number has changed since the last GPRS detach, or if it is the very first attach, the new SGSN/MME  215  updates the HLR  240  by sending an update location message to the HLR (steps  356  and  358 ). The update location message includes an SGSN/MME number, SGSN/MME address, the IMSI, and the like. 
         [0026]    The HLR  240  compares the SGSN/MME number with records and sends a cancel location message (including IMSI and/or cancellation type) to the old SGSN/MME (steps  362  and  364 ). The old SGSN/MME  220  acknowledges with a cancel location acknowledgement (ACK) with IMSI (step  366 ). The HLR  240  then sends an insert subscriber data message to the new SGSN/MME  215  (step  368 ). The insert subscriber data message includes the IMSI, GPRS/SAE subscription data, packet data protocol (PDP) type, PDP address, access point name (APN), quality of service (QoS), virtual public land mobile network (VPLMN) allowed, and a multi-system registration accepted or rejected indication. 
         [0027]    The new SGSN/MME  215  checks if the WTRU  205  is not allowed in the new routing area (RA) (step  370 ). If due to regional subscription restrictions or access restrictions the WTRU is not allowed to attach in the RA, the new SGSN/MME  215  rejects the attach request with an appropriate cause, and may return an insert subscriber data acknowledgement (ACK) (including the IMSI and/or an SGSN area restricted message) to the HLR  240  (step  372 ). If the subscription checking fails for other reasons, the new SGSN/MME also rejects the attach request with an appropriate cause and returns an insert subscriber data ACK (including the IMSI and/or an SGSN area restricted message) to the HLR (step  372 ). If all checks are successful, the new SGSN/MME  215  constructs an MM context for the WTRU  205  (step  374 ) and returns an insert subscriber data ACK (including the IMSI) to the HLR  240  (step  376 ). The HLR  240  then updates the MM context (step  378 ) and sends an update location ACK to the new SGSN/MME  215  (step  380 ). 
         [0028]    Referring to  FIG. 2C , an attach procedure  450  for a GPRS with IMSI attach type is presented in greater detail. If the attach type indicated in the attach request indicates a combined GPRS/IMSI attach, the new VLR  235  should be updated. The new SGSN/MME  215  sends a location update request to the new VLR  235  (step  452 ). The location update request includes a new LAI, the IMSI, an SGSN number, a location update type and the like. 
         [0029]    The new VLR  235  creates an association with the new SGSN/MME  215  by storing the SGSN number. If the location update is inter-mobile switching center (MSC), the new VLR  235  sends an update location message (including the IMSI and a new VLR address) to the HLR  240  (step  454 ). The HLR  240  then sends a cancel location message to an old VLR  245  (step  456 ). The old VLR  245  acknowledges with a cancel location ACK (step  458 ). The HLR  240  sends an insert subscriber data message (including the IMSI and/or subscriber data) to the new VLR  235  (step  460 ). The new VLR  235  acknowledges with an insert subscriber data ACK with IMSI (step  462 ). After finishing the inter-MSC location update procedures, the HLR  240  responds with an update location ACK to the new VLR  235  with the IMSI (step  464 ). The new VLR  235  responds with a location update accept message (including VLR TMSI) to the new SGSN/MME  215  (step  466 ). 
         [0030]    A second attach type is also shown in  FIG. 2C , which is an SAE/non-3GPP with IMSI attach procedure. In step  468 , the new SGSN/MME  215  sends a create PDP context request message to the GGSN/3G aGW  225 . The GGSN/3G aGW  225  responds with a create PDP context response message to the new SGSN/MME  215  (step  470 ). The new SGSN/MME  215  sends a message for establishing a tunnel to the GGSN/3G aGW (step  472 ) and a radio access bearer (RAB) to the RAN (step  474 ). An RAB then is established between the WTRU  205  and the RAN  210 , and the RAN  210  sends a tunnel establishment and RAB setup ACK to the new SGSN/MME  215  (step  476 ) after a GTP-U tunnel is established between the RAN and the GGSN/3G aGW (step  478 ). 
         [0031]    Referring to  FIG. 2D , an attach procedure  550  for an SAE with IMSI attach type is presented. The GGSN/3G aGW  225  recognizes the multimode registration and invokes non-3GPP registration and mobility protocol (step  552 ). The GGSN/3G aGW  225  sends a non-3GPP attach request message to an SAE aGW (step  554 ). The SAE aGW  230  establishes a session state for the WTRU  205  and inter system mobility registration, (e.g., MIP), (step  556 ). A QoS profile is then downloaded from a policy and charging rule function (PCRF) unit  250  (step  558 ). The SAE aGW  230  sends a non-3GPP attach accept message to the GGSN/3G aGW  225  (step  560 ). The GGSN/3G aGW  230  sends a 3GPP-based and non-3GPP-based attach accept message to the new SGSN/MME  215  (step  562 ). 
         [0032]    The new SGSN/MME  215  forwards the attach accept message to the WTRU  205  indicating success or failure of the 3GPP and non-3GPP attachment (step  564 ). The WTRU  205  then sends an attach complete message to the new SGSN/MME (step  266 ). 
         [0033]      FIG. 3  is a block diagram of a WTRU  300  configured to implement the attachment procedures of  FIGS. 2A-2D . The WTRU  300  includes a transmitter  305 , a receiver  310 , a processor  315  and an antenna  320 . 
         [0034]    The processor  315  is configured to generate at least one IE that indicates at least one of the capability of the WTRU and the type of mobility management required to support the WTRU in a non-3GPP system. The IE may indicate that the WTRU is SAE capable or LTE capable. The IE may indicate that GTP or MIP mobility management or is required to support the WTRU in a non-3GPP system. For MIP mobility management, the IE may further indicate whether MIPv4, proxy MIP or MIPv6 mobility management is required. The attach request message may include an IMSI and an attach type indicator. The attach type indicator may indicate a 2G multimode attachment, a 3G multimode attachment or an SAE multimode attachment. 
         [0035]    The transmitter  305  is configured to transmit an attach request message including the at least one IE and an IMSI. Alternatively, the transmitter  305  may be configured to transmit an attach request message including a P-TMSI, an old RAI and an attach type indicator. The receiver  310  is configured to receive an attach accept message and an identity request message. 
         [0036]      FIG. 4  is a block diagram of an SGSN/MME  400  configured to implement the attachment procedures of  FIGS. 2A-2D . The SGSN/MME  400  includes a transmitter  405 , a receiver  410 , a processor  415  and an antenna  420 . The receiver  410  is configured to receive an attach request message including at least one of an attach type indicator and preferred mobility management information. The processor  415  is configured to determine an extent of a registration process based on the attach type indicator. The extent of the registration process may be GPRS only, GPRS and SAE/LTE only, or 3GPP and non-3GPP. 
         [0037]      FIG. 5  is a block diagram of a GGSN/3G aGW  500  configured to implement the attachment procedures of  FIGS. 2A-2D . The GGSN/3G aGW  500  includes a transmitter  505 , a receiver  510 , a processor  515  and an antenna  520 . The processor  515  is configured to recognize a multimode registration and invoke non-3GPP registration/mobility protocol. The transmitter  505  is configured to transmit a non-3GPP attach request message. The receiver  510  is configured to receive a non-3GPP attach accept message in response to the non-3GPP attach request message. 
         [0038]      FIG. 6  is a block diagram of an SAE aGW  600  configured to implement the attachment procedures of  FIGS. 2A-2D . The SAE aGW  600  includes a transmitter  605 , a receiver  610 , a processor  615  and an antenna  620 . The receiver  610  is configured to receive a non-3GPP attach request message and a quality of service (QoS) profile. The processor  615  is configured to establish a session state for a WTRU and inter-system mobility registration. The transmitter  605  is configured to transmit a non-3GPP attach accept message to indicate that the inter-system mobility registration has been completed. The inter-system mobility registration may be a MIP registration. 
         [0039]    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). 
         [0040]    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. 
         [0041]    A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) module.