Abstract:
A method and apparatus for supporting routing area update procedures in a single tunnel general packet radio services (GPRS)-based wireless communication system are disclosed. A wireless transmit/receive unit (WTRU) sends a routing area update request message to a serving general packet radio service (GPRS) support node (SGSN) via a radio network controller (RNC). The SGSN sends an update packet data protocol (PDP) context request message to a gateway GPRS support node (GGSN). The GGSN sends an update PDP context response message to the SGSN. The SGSN sends a tunnel establishment request message to the RNC and a single tunnel is established between the RNC and the GGSN. For handover operations, a previous single tunnel established between the GGSN and another RNC is released and the routing area update is accepted and completed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/780,235 filed Mar. 8, 2006, which is incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION  
       [0002]     The present invention is related to a wireless communication system. More particularly, the present invention is related to a method and apparatus for supporting routing area update in a single tunnel general packet radio service (GPRS)-based wireless communication system.  
       BACKGROUND  
       [0003]      FIG. 1  shows a conventional GPRS/third generation ( 3 G) wireless communication system architecture  100  that shows various interfaces/protocols as well as user data transfer interfaces between various network entities. The wireless communication system  100  includes at least one serving GPRS support node (SGSN)  105  and at least one gateway GPRS support node (GGSN)  110 . The wireless communication system  100  further comprises a universal terrestrial radio access network (UTRAN)  115  which includes one or more radio access networks (RANs), base station systems (BSSs) and radio network controllers (RNCs), (not shown). The system  100  also comprises a plurality of wireless transmit/receive units (WTRUs)  120 , each including a terminal equipment (TE)  125  coupled to a mobile terminal (MT)  130 . The mobility in the wireless communication system  100  is facilitated by anchoring an Internet Protocol (IP) session at the GGSN  110  and allowing for multi-level mobility by supporting mobility management (MM) protocols for IP and non-IP traffic/services provided by the SGSN  105 .  
         [0004]      FIG. 2A  shows how dual tunnels are established in the conventional wireless communication system  100  of  FIG. 1  to provide IP connectivity for user plane traffic. As shown in  FIG. 2A , a GPRS tunnelling protocol (GTP) user plane (GTP-U) tunnel  220  is established between a GGSN  205  and an SGSN  210 , and a second user plane tunnel  225  is established between the SGSN  210  and a radio network controller (RNC)  215 . Both tunnels are dedicated to the same user. The GTP tunnel  220  has a user plane and a control plane. The user tunnel  225  is an IP tunnel having a user plane and a RAN application part (RANAP) control plane used for control messaging.  
         [0005]     A routing area update (RAU) is used to minimize the paging traffic within a wireless communication system that is grouped into clusters. Each cluster includes a group of cells (Node-Bs). Each cluster is defined by a unique identifier, (i.e., routing area identifier (ID)). Those WTRUs in the wireless communication system that travel across boundaries of the clusters have to perform a registration process called a routing area update. In the RAU, the WTRU informs the core network regarding which area of the system it is operating in. If the WTRU receives a terminated call, the core network pages the WTRU in the last known routing area. This eliminates the need to send a paging message for the WTRU throughout the entire system, which in turn significantly reduces the amount of signalling across the system. Thus, more processing power is allocated to user traffic. The RAU may require the establishment of a new connection between a GGSN and a new RNC. New processes and message formats are needed for a single tunnel approach as compared to those existing in a two tunnel approach.  
         [0006]     In the evolution toward an all IP Network (AIPN), most of the services and applications are migrating toward IP based platforms. This migration requires IP connectivity, and the generated traffic does not have to be terminated at the SGSN. Therefore, a single tunnel functionality is desirable to reduce the delay and processing power at the SGSN.  
       SUMMARY  
       [0007]     The present invention is related to a method and apparatus for supporting routing area update using a single tunnel in a GPRS/3G network and beyond. A wireless transmit/receive unit (WTRU) sends an activate packet data protocol (PDP) context request to an SGSN via an RNC, and the SGSN sends a create PDP context request to a GGSN. The create PDP context request includes a PDP type, a PDP address, an access point name (APN), a single tunnel request, an RNC tunnel endpoint identity (TEID) and quality of service (QoS) data, whereby a single tunnel is established between the GGSN and the RNC.  
         [0008]     In one embodiment, a WTRU sends a routing area update request message to an SGSN via an RNC. The SGSN sends an update PDP context request message to a GGSN. The GGSN sends an update PDP context response message to the SGSN. The SGSN sends a tunnel establishment request message to the RNC, and a single tunnel is established between the RNC and the GGSN. For handover operations, a previous single tunnel established between the GGSN and another RNC is released and the routing area update is accepted and completed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     A more detailed understanding of the invention may be had from the following description of a preferred embodiment, given by way of example and to be understood in conjunction with the accompanying drawings wherein:  
         [0010]      FIG. 1  shows a conventional GPRS and 3G wireless communication system;  
         [0011]      FIG. 2A  shows the conventional establishment of dual tunnels;  
         [0012]      FIG. 2B  shows the establishment of a single tunnel in accordance with the present invention;  
         [0013]      FIG. 3  shows a prior art tunnel protocol stack;  
         [0014]      FIG. 4  shows a single tunnel protocol stack configured in accordance with the present invention;  
         [0015]      FIG. 5  shows a single tunnel establishment procedure, (PDP context activation), which is implemented in accordance with the present invention;  
         [0016]      FIG. 6  shows a single tunnel intra-SGSN inter-RNC routing area update procedure in accordance with one embodiment of the present invention; and  
         [0017]      FIGS. 7A and 7B , taken together, show a single tunnel intre-SGSN routing area update procedure in accordance with another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     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.  
         [0019]     The features of the present invention may be incorporated into an integrated circuit (IC) or be configured in a circuit comprising a multitude of interconnecting components.  
         [0020]     In accordance with the present invention, the mobility in GPRS, ( 3 G or beyond), systems is facilitated by anchoring the IP session at the home GGSN and allowing for multi-level mobility, and by supporting existing MM protocols for non-IP traffic/services provided by the SGSN.  
         [0021]      FIG. 2B  shows a single user-plane tunnel approach in accordance with the present invention. A single user plane tunnel  230  is used to reduce the delay and processing power of an SGSN  210 ′. In the two-tunnel approach shown in  FIG. 2A , the SGSN  210  terminates both the GTP tunnel  220  and a user plane tunnel  225  to the RNC  215 , which means that the SGSN  210  decodes the packets traveling in both directions and translates them into the different protocol formats of the two tunnels  220  and  225 . In a single tunnel approach shown in  FIG. 2B , the SGSN  210 ′ only establishes a tunnel between the GGSN  205 ′ and the RNC  215 ′ via two separate interfaces/protocols, (RANAP-C and GTP-C). In the single tunnel approach, the SGSN  210 ′ is no longer involved in the user plane traffic. Thus, the user traffic passes through the SGSN  210 ′ unchanged, (i.e., unaltered), in both directions. The SGSN  210 ′ is no longer involved in the user plane processing. Only the RNC  215 ′ and the GGSN  205 ′ are allowed to perform/act on the user plane traffic. The SGSN  210 ′ only manages the control traffic, including MM, RAU, and the like, associated with the user and its IP based traffic. The SGSN  210 ′ connects an RNC  215 ′ and a GGSN  205 ′ using a GTP control plane to communicate with the GGSN  205 ′ and a RANAP control plane to communicate with the RNC  215 ′. When a handoff occurs between RNCs, the SGSN  210 ′ is responsible for providing the GGSN  205 ′ with the new RNC TEID information and the establishment of the single tunnel  230 .  
         [0022]      FIG. 3  shows a prior art tunnel protocol stack according to existing GPRS protocol. A GTP-U tunnel transfers, (i.e., tunnels), user data between a UTRAN (which includes RANs, BSSs and RNCs) and a 3G-SGSN, and between the 3G-SGSN and a 3G-GGSN.  
         [0023]      FIG. 4  shows a user plane in the single tunnel protocol stack in accordance with the present invention, in which the user plane tunnel from the UTRAN does not terminate at the 3G-SGSN. Instead, the UTRAN terminates at the 3G-GGSN. The IP Tunnel shown in UTRAN and GGSN can be GTP based or any generic IP-Tunnel. In a preferred embodiment, the GTP-U tunnel is used as an IP tunnel.  
         [0024]      FIG. 5  is a signaling diagram of a process for single tunnel establishment in accordance with the present invention. The single tunnel functionality reduces the delay and processing power at the SGSN by reducing the need for protocol translation between the RNC and GGSN interfaces, and by enabling direct user plane tunnel between the RAN/RNC and the GGSN within the packet switched (PS) domain. However, the single tunnel approach will not eliminate the need for the SGSN to manage control traffic for IP based traffic. The SGSN is still needed for the control plane signalling, MM and call/session management, and makes a decision when to establish a single tunnel rather than establishing dual tunnels.  
         [0025]     In the case of a single tunnel, the SGSN should connect the RAN/RNC TEID and the GGSN TEID for user plane by informing each end point of the tunnel of the corresponding TEID of the other end point, (i.e., informing the GGSN of the RNC TEID and informing the RNC of the GGSN TEID). In the case of a handoff between RNCs, the SGSN is responsible for updating and providing the GGSN with new RNC TEID information and the establishment of the single tunnel.  
         [0026]      FIG. 5  shows a single tunnel establishment procedure, (packet data protocol (PDP) context activation), which is implemented in a wireless communication system including a WTRU  505 , a radio access network (RAN)/radio network controller (RNC)  510 , an SGSN  515  and a GGSN  520  in accordance with the present invention. The WTRU  505  sends an activate PDP context request to the SGSN  515  that includes PDP type, PDP address, APN, quality of service (QoS) data and the like), (step  525 ). The SGSN  515  validates the activate PDP context request, selects an APN), and maps the APN to the GGSN  520  (step  530 ). The SGSN  515  determines if a single tunnel is supported and/or requested, and notes the existence of an RNC TEID (step  530 ). The SGSN  515  creates a PDP context request that includes PDP Type, PDP Address, APN, a single tunnel request, an RNC TEID, QoS and the like), (step  535 ). The GGSN  520  creates a PDP context response that includes PDP Type, PDP Address, APN, an indicator that the single tunnel is granted, GGSN TEID, QoS and the like (step  540 ). The WTRU  505  and the RAN/RNC  510  establish a radio access bearer (RAB) (step  545 ). In step  550 , the SGSN  515  and the RAN/RNC  510  exchange tunnel setup signaling that includes a mobile station international subscriber directory number (MSISDN), a PDP address and a GGSN TEID, and the SGSN  515  sends tunnel establishment information to the RAN/RNC  510  after receiving an indication of acceptance from the GGSN to establish the tunnel. The SGSN  515  sends an update PDP context request to the GGSN  520  (step  560 ) to establish the new tunnel by informing the GGSN  520  of the RNC TEID associated with the request, and the GGSN  520  sends an update PDP context response to the SGSN  515  (step  565 ) confirming/rejecting the establishment of the tunnel and the associated attributes, (RNC TEID, PDP type, PDP address, user ID, and the like). The SGSN  515  inserts the GGSN address in its PDP context, sends the PDP address received from the GGSN (step  570 ) and prepares for the response to be sent down to the WTRU  505 . Thus, if necessary, the SGSN  515  updates the PDP context in the GGSN  520  to reflect any changes in the QoS attributes resulting from the RAB establishment of step  545 . Tunnel establishing signaling is exchanged between the RAN/RNC  510  and the GGSN  520  including the MSISDN, PDP address, RNC TEID and GGSN TEID (step  575 ). The SGSN  515  sends an activate PDP context accept signal to the WTRU  505  that indicates the presence of a single tunnel (step  580 ).  
         [0027]      FIG. 6  shows a single tunnel intra-SGSN inter-RNC routing area update procedure, which is implemented in a wireless communication system including a WTRU  605 , an old base station system (BSS)/RNC  610 , a new BSS/RNC  615 , an SGSN  620 , a GGSN  625  and a home location register (HLR)  630  in accordance with the present invention.  
         [0028]     Still referring to  FIG. 6 , an old tunnel is established between the old BSS/RNC  610  and the GGSN  625  (step  635 ). The WTRU  605  sends a routing area update (RAU) request, which may include a packet temporary mobile subscriber identity (P-TMSI), old routing area identification (RAI), old P-TMSI signature, an update type and the like, to the new BSS/RNC  610  and the SGSN  620  (step  640 ). The update type indicates whether or not the routing area update is periodic. Security functions are then established between the WTRU  605 , the SGSN  620  and the HLR  630  (step  650 ). The SGSN  620  sends an update PDP context request to the GGSN  625  (step  655 ). The GGSN  625  then sends an update PDP context response to the SGSN  620  (step  660 ). The SGSN  620  sends a tunnel establishment request to the new BSS/RNC  615  (step  665 ). In step  655 , the SGSN  620  establishes the new tunnel between the GGSN  625  and the new BSS/RNC  615  by sending the TEID of the new BSS/RNC  615  to the GGSN  625  in the update PDP context request of step  660 . If the request is granted, the GGSN  625  confirms the request back to the SGSN  620  in step  660 . In step  665 , the SGSN  620  establishes the other end of the tunnel to the new BSS/RNC  615  by sending the TEID of the GGSN  625  to the new BSS/RNC  615  via the tunnel establishment message. In step  670 , the BSS/RNC  615  acknowledges the request and indicates the operation success to the SGSN  620 . Now, a new tunnel is established in step  675 . Optionally, there may be additional update PDP context requests depending on the final set of QoS attributes. The new BSS/RNC  615  then sends a tunnel establishment response to the SGSN  620  (step  670 ). A new tunnel between the new BSS/RNC  615  and the GGSN  625  is then established (step  675 ). Upon the successful establishment of the new tunnel, the SGSN  620  releases the old tunnel by sending a release request to the old BSS/RNC  610  in step  680 . A release response is sent from the old BSS/RNC  610  to the SGSN  620  (step  685 ). A routing area update accept is sent from the SGSN  620  to the new BSS/RNC  615  and the WTRU  605  (step  690 ). A routing area update complete message is then sent from the WTRU  605  to the new BSS/RNC  615  and the SGSN  620  (step  695 ).  
         [0029]      FIGS. 7A and 7B , taken together, show a single tunnel intre-SGSN routing area update procedure, which is implemented in a wireless communication system including a WTRU  705 , an old BSS/RNC  710 , a new BSS/RNC  715 , a new SGSN  720 , an old SGSN  725 , a GGSN  728  and an HLR  730  in accordance with the present invention.  
         [0030]     Referring to  FIG. 7A , an old tunnel is established between the old BSS/RNC  710  and the GGSN  728  (step  732 ). The WTRU  705  sends a routing area update request, which may include a P-TMSI, old RAI, old P-TMSI signature, an update type and the like, to the new BSS/RNC  734  and the new SGSN  720  (step  734 ). The update type indicates whether or not the routing area update is periodic. The new SGSN  720  sends an SGSN context request to the old SGSN  725  (step  736 ). The old SGSN  725  sends an SGSN context response to the new SGSN  720  (step  738 ). Security functions are then established between the WTRU  705 , the new SGSN  720  and the HLR  730  (step  740 ). The new SGSN  620  sends an SGSN context acknowledge message to the old SGSN  725  (step  742 ) and sends an update PDP context request to the GGSN  728  (step  655 ) which indicates a single tunnel and the TEID of the new BSS/RNC  715 . The GGSN  728  then sends an update PDP context response to the new SGSN  720  (step  746 ). The new SGSN  720  sends a tunnel setup message to the new BSS/RNC  715  which indicates the MSISDN, PDP address and the GGSN TEID (step  748 ). The new BSS/RNC  715  then sends a tunnel setup acknowledgement message to the new SGSN (step  750 ). A new tunnel between the new BSS/RNC  715  and the GGSN  728  is then established (step  752 ).  
         [0031]     In the case of pending traffic in the system using the old tunnel, the traffic is forwarded from the old BSS/RNC  610  to the new BSS/RNC  615  for service continuity. Referring to  FIG. 7B , after the new tunnel is established, forward packets are sent from the new SGSN  720  to the old SGSN  725  (step  754 ). In step  754 , forward packets are sent from the new SGSN  720  to the old SGSN  725 . In step  756 , forward packets are sent from the old SGSN  725  to the old BSS/RNC  710 . In step  758 , packets are forwarded from the old BSS/RNC  710  to the new BSS/RNC  715 . In step  760 , the old BSS/RNC  710  sends a forward packets acknowledgement message to the old SGSN  725 . In step  762 , the old SGSN  725  sends a forward packets acknowledgement message to the new SGSN  720 . In step  764 , the new SGSN sends update location message to the HLR  730 . In step  766 , the HLR  730  sends a cancel location message to the old SGSN  725 . In step  768 , release signaling, (e.g., a release request message and a release response message), is exchanged between the old BSS/RNC  710  and the old SGSN  725 . In step  770 , a cancel location acknowledgement message is sent from the old SGSN  725  and the HLR  730 . In step  772 , insert subscriber data is sent from the HLR  730  to the new SGSN  720 . In step  774 , the new SGSN  720  sends an insert subscriber data acknowledgement message to the HLR  730 . In step  776 , the HLR  730  sends an update location acknowledgement message to the new SGSN  720 . In step  778 , the new SGSN  720  sends a routing area update accept message to the new BSS/RNC  715  and the WTRU  705 . In step  780 , the WTRU  705  sends a routing area update complete message to the new BSS/RNC and the new SGSN  720 .  
         [0032]     Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the preferred embodiments or in various combinations with or without other features and elements of the present invention. The methods or flow charts provided in the present invention may be implemented in a computer program, software, or firmware tangibly embodied in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs).  
         [0033]     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.  
         [0034]     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.