Abstract:
An apparatus and method makes a decision whether or not to handover a wireless transmit-receive unit to a new network in a wireless or fixed network communication system. In a specific embodiment, a media-independent handover application server, operating according to IEEE 802.21 protocol, exchanges information with a server by using a Third Generation Partnership Project standardized interface. The method allows for an IMS based handover server to extract user preference and subscription information from a subscription server. The improvement allows new kinds of information to be exchanged between the handover and subscription server for optimized handover decisions.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/913,841 filed on Apr. 25, 2007, which is incorporated by reference as if fully set forth. 
     
    
     TECHNOLOGY FIELD 
       [0002]    A method and apparatus related to wireless communications. More particularly, a method and apparatus enabling a server to download user preferences and subscriptions, further enabling handover between networks, are disclosed. 
       BACKGROUND 
       [0003]    The IEEE 802.21 standard defines three main services that help mobility management entities in a terminal and network to make handover and handover related decisions. These are the Media Independent Handover (MIH) Information, Event, and Command services. 
         [0004]    The Third Generation Partnership Project (3GPP) group is currently working on the radio and architecture aspects of the Long Term Evolution of the 3GPP cellular system. Within this framework, mobility management, and specifically handover between different RATs (Radio Access Technologies), have received particular attention. 
         [0005]    Currently, there are no standardized interactions between 3GPP Core Network elements and any IEEE mobility management entity (such as an 802.21 MIH server). However, it has been previously shown how an MIH server may be introduced as an Internet Protocol Multimedia Subsystem (IMS) Application Server (AS). Functionally, this MIH AS uses the 802.21 protocol, using the Session Initiation Protocol (SIP)-based signaling for IMS, to communicate with a suitable wireless transmit/receive unit (WTRU). Further a generic protocol has been developed that allows this MIH AS to make handover related decisions. The handover related decisions are performed by implementing the Media Independent Handover Function (MIHF) entity, as standardized by the IEEE 802.21 Working Group, and an upper-level mobility management entity called the Mobility Controller. This concept is shown in  FIGS. 1A and 1B . 
         [0006]    The 3GPP group has mapped messages of a particular interface, the Sh interface, onto the Diameter Protocol. Table 1 shows information elements (IEs) that are accessible via the Sh interface. The Diameter protocol is an Internet Engineering Task Force (IETF) protocol for authentication, authorization and accounting. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Data accessible via Sh interface 
               
             
          
           
               
                 Data 
                   
                 Defined 
                   
                   
               
               
                 Ref. 
                 XML tag 
                 in 
                 Access key 
                 Operations 
               
               
                   
               
             
          
           
               
                 0 
                 RepositoryData 
                 7.6.1 
                 IMS Public User Identity or 
                 Sh-Pull, Sh-Update, 
               
               
                   
                   
                   
                 Public Service Identity + 
                 Sh-Subs-Notif 
               
               
                   
                   
                   
                 Data-Reference + Service- 
               
               
                   
                   
                   
                 Indication 
               
               
                 10 
                 IMSPublicIdentity 
                 7.6.2 
                 IMS Public User Identity 
                 Sh-Pull 
               
               
                   
                   
                   
                 or Public Service Identity or 
               
               
                   
                   
                   
                 MSISDN + Data-Reference + 
               
               
                   
                   
                   
                 Identity-Set (values other than 
               
               
                   
                   
                   
                 ALIAS_IDENTITIES) 
               
               
                 10 
                 IMSPublicIdentity 
                 7.6.2 
                 IMS Public User Identity + 
                 Sh-Pull, Sh-Subs-Notif 
               
               
                   
                   
                   
                 Data-Reference + Identity-Set 
               
               
                   
                   
                   
                 (with value 
               
               
                   
                   
                   
                 ALIAS_IDENTITIES) 
               
               
                 11 
                 IMSUserState 
                 7.6.3 
                 IMS Public User Identity + 
                 Sh-Pull, Sh-Subs-Notif 
               
               
                   
                   
                   
                 Data-Reference 
               
               
                 12 
                 S-CSCFName 
                 7.6.4 
                 IMS Public User Identity or 
                 Sh-Pull, Sh-Subs-Notif 
               
               
                   
                   
                   
                 Public Service Identity + 
               
               
                   
                   
                   
                 Data-Reference 
               
               
                 13 
                 InitialFilterCriteria 
                 7.6.5 
                 IMS Public User Identity or 
                 Sh-Pull, Sh-Subs-Notif 
               
               
                   
                   
                   
                 Public Service Identity + 
               
               
                   
                   
                   
                 Data-Reference + Server- 
               
               
                   
                   
                   
                 Name 
               
               
                 14 
                 LocationInformation 
                 7.6.6 
                 MSISDN + Data-Reference+ 
                 Sh-Pull 
               
               
                 15 
                 UserState 
                 7.6.7 
                 Requested-Domain 
               
               
                 16 
                 Charging information 
                 7.6.8 
                 IMS Public User Identity or 
                 Sh-Pull 
               
               
                   
                   
                   
                 Public Service Identity or 
               
               
                   
                   
                   
                 MSISDN + Data-Reference 
               
               
                 17 
                 MSISDN 
                 7.6.9 
                 IMS Public User Identity or 
                 Sh-Pull 
               
               
                   
                   
                   
                 MSISDN + Data-Reference 
               
               
                 18 
                 PSIActivation 
                 7.6.10 
                 Distinct Public Service Identity + 
                 Sh-Pull, Sh-Update, 
               
               
                   
                   
                   
                 Data-Reference 
                 Sh-Subs-Notif 
               
               
                 19 
                 DSAI 
                 7.6.11 
                 Public User Identity or Public 
                 Sh-Pull, Sh-Update, 
               
               
                   
                   
                   
                 Service Identity + Data- 
                 Sh-Subs-Notif 
               
               
                   
                   
                   
                 Reference + DSAI-Tag + 
               
               
                   
                   
                   
                 Server-Name 
               
               
                 20 
                 AliasesRepositoryData 
                 7.6.12 
                 IMS Public User Identity + 
                 Sh-Pull, Sh-Update, 
               
               
                   
                   
                   
                 Data-Reference + Service- 
                 Sh-Subs-Notif 
               
               
                   
                   
                   
                 Indication 
               
               
                   
               
             
          
         
       
     
         [0007]    For the Diameter application standardized by 3GPP the Application ID is 16777217. The Sh interface messages map onto the standardized Diameter protocol messages as shown in the Table 2. 
         [0000]                                          TABLE 2                   Sh message to Diameter Command mapping            Sh message   Source   Destination   Command-Name   Abbreviation               Sh-Pull   AS   HSS   User-Data-Request   UDR       Sh-Pull Resp   HSS   AS   User-Data-Answer   UDA       Sh-Update   AS   HSS   Profile-Update-Request   PUR       Sh-Update Resp   HSS   AS   Profile-Update-Answer   PUA       Sh-Subs-Notif   AS   HSS   Subscribe-Notifications-Request   SNR       Sh-Subs-Notif Resp   HSS   AS   Subscribe-Notifications-Answer   SNA       Sh-Notif   HSS   AS   Push-Notification-Request   PNR       Sh-Notif Resp   AS   HSS   Push-Notification-Answer   PNA                    
The Command Names shown in Table 2 have Command Codes that are used in the Diameter header, as shown in  FIG. 2 . A list of the command codes is shown in Table 3.
 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Command Codes in Diameter Header 
               
             
          
           
               
                 Command-Name 
                 Abbreviation 
                 Code 
                 Section 
               
               
                   
               
               
                 User-Data-Request 
                 UDR 
                 306 
                 6.1.1 
               
               
                 User-Data-Answer 
                 UDA 
                 306 
                 6.1.2 
               
               
                 Profile-Update-Request 
                 PUR 
                 307 
                 6.1.3 
               
               
                 Profile-Update-Answer 
                 PUA 
                 307 
                 6.1.4 
               
               
                 Subscribe-Notifications-Request 
                 SNR 
                 308 
                 6.1.5 
               
               
                 Subscribe-Notifications-Answer 
                 SNA 
                 308 
                 6.1.6 
               
               
                 Push-Notification-Request 
                 PNR 
                 309 
                 6.1.7 
               
               
                 Push-Notification-Answer 
                 PNA 
                 309 
                 6.1.8 
               
               
                   
               
             
          
         
       
     
       SUMMARY 
       [0008]    A method and apparatus that allows the MIH Application Server in a wireless or fixed network communication system to download user preferences and subscriptions from the Home Subscription Server (HSS) are disclosed. The method and apparatus allow an IMS based handover server to extract user preference and subscription information from a subscription server. This improvement allows new kinds of information to be exchanged between the handover and subscription server for optimized handover decisions. The MIH AS may use this information to update its database. The MIH AS may also allow the Mobility Controller, residing within it, to use this information to assist the MIHF logical entity, also residing within it, to make handover related decisions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    A more detailed understanding may be had from the following description, given by way of example and to be understood in conjunction with the accompanying drawings wherein: 
           [0010]      FIGS. 1A and 1B  are diagrams of an existing system and protocol for handover related decisions; and 
           [0011]      FIG. 2  is a diagram of an existing header format; 
           [0012]      FIG. 3  is a flow chart of a method of obtaining information about user preferences and subscriptions; 
           [0013]      FIGS. 4A and 4B  are flow charts of a method of updating the user data; and 
           [0014]      FIG. 5  is a block diagram of a wireless communication system. 
       
    
    
     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 or fixed network 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 or fixed network environment. 
         [0016]      FIG. 1A  is a diagram of an existing system and protocol  100  for handover related decisions. The protocols shown in  FIG. 1A  include normal IMS registration  110 , session setup with 802.21 AS using SIP  120  (signaling plane), and 802.21 registration  130  (user plane—directly over IP with IPsec, where IPsec is the security standard for IP traffic). The wireless or fixed network operator may operate several different IMS domains. The user selects the access to a specific IMS domain by means of his ISIM (IMS SIM) application contained in his UICC/SIM card. In this example, the operator assigns a specific IMS domain by means of the S-CSCF selection process where the corresponding MIH AS resides  110 . 
         [0017]      FIG. 1B  is a diagram of an existing system and protocol  100  for handover related decisions. The protocols shown in  FIG. 1B  include VoIP session setup  140 , VoIP data exchange  150 , reporting of standardized 802.21 link events to initiate the inter-technology handover  160 , and standardized 802.21 commands used to control links and execute the handover  170 . 
         [0018]    As can be seen from the signal flow diagrams and the prototype architecture in  FIGS. 1A and 1B , the Mobility Controller should decide whether to switch the user to the WLAN, or in general, any other RAT. To make an informed decision the Mobility Controller  180  needs to have the user subscription profile and preferences which are generally stored in the HSS (not shown) to which it currently has no ready access. This is the problem that the embodiments discussed below aim to solve. 
         [0019]      FIG. 2  is a diagram of an existing header format  200 . The Sh interface, mapped to the Diameter protocol, runs over TCP and has a header format as shown in  FIG. 2 . 
         [0020]    To overcome the problems discussed above, a method to assist a media-independent network handover which can enable a first server to obtain information about a WTRU is needed. This method can apply to, for example, an IMS-based server or an MIH server in the IMS domain. Upon receiving network link information from the WTRU, the server may transmit identity information for the WTRU to a subscription server. The network link information can include, but is not limited to, radio strength measurements, traffic loss parameters, bit error rate information, or a handover request. Upon receiving information from the subscription server, the first server decides whether to handover the WTRU to a new network. 
         [0021]      FIG. 3  is a flow chart of a method of obtaining information about user preferences and subscriptions  300  using an optional Sh interface. The MIH AS (through the Mobility Controller) contacts the HSS using the optional Sh interface that has been standardized by the 3GPP group for interaction between the HSS and an IMS Application Server, as described above. 
         [0022]    Upon receiving a ‘MIH_Register Request’ message from an IMS registered user  310 , the Mobility Controller is expected to contact the HSS by invoking the standardized ‘Sh-Pull’ procedure  320 . This procedure allows the Mobility Controller to forward the User Identity to the HSS  330  and receive data that is stored for the user in the HSS  340 . The HSS responds with a “Sh-Pull Response” message  350  that contains the User Data stored as an Attribute Value Pair (AVP) containing the Information Elements (IE&#39;s) shown in Table 1. 
         [0023]    In another embodiment of the present invention, information is added to the information list supplied by the HSS, shown in Table 1. An Information Element (IE) called “Allowed Networks” is added to the list shown in Table 1 that includes the Network IDs of all operators that the home operator has a roaming agreement with and that the user has subscribed for. 
         [0024]    The creation of additional IEs would allow the Mobility Controller to make a handover decision if the WTRU detects a foreign network. One example would be to create an IE called “User Preferences”. This “User Preferences” IE preferably contains such information as whether the user preferences pertain to cost to connect to the network or the speed of the network, for example. Another example would be to enhance the Location Information IE, in Table 1, with information (geographical, for example) that would allow the MIH AS to determine (using its database) if a different MIH AS in closer proximity to the WTRU exists. 
         [0025]      FIGS. 4A and 4B  are flow charts of a method of updating the user data. As shown in  FIGS. 4A and 4B , the Mobility Controller/MIH AS database may, at any time, update the user data by invoking the “Sh-Update” procedure  410  to which the HSS is expected to respond with the “Sh-Update Response” message  420 . The Mobility Controller/MIH AS database may also subscribe to notifications of update in user data profile  430  by sending a “Sh-Subs-Notif” message to the HSS  440 . The HSS in turn may notify the Mobility Controller/MIH AS database of any updates in the User Data by sending a “Sh-Notif” message  450 . 
         [0026]      FIG. 5  is a block diagram of a wireless communication system  500  including a wireless transmit receive unit  505  and an AP  510 . The WTRU  505  and the AP  510  communicate via a wireless communication link,  512 . 
         [0027]    As shown in  FIG. 5 , the WTRU  515  includes an MIH function (MIHF)  515 , a processor  520 , at least one transceiver ( 525   a ,  525   b ). The processor  520  is attached to the MIHF  515  and each of the transceivers  525   a ,  525   b . The MIHF  515  is configured to carry out media independent handover related processes, including generating an MIH capabilities discovery request, and processing an MIH capabilities response. 
         [0028]    Also shown in  FIG. 5 , the AP  510  includes an MIHF  530 , a processor  535 , at least one transceiver ( 540   a ,  540   b ). The processor  535  is attached to the MIHF  530  and each of the transceivers  540   a ,  540   b . The MIHF  530  is configured to carry out media independent handover related processes, including processing an MIH capabilities discovery request, and generating an MIH capabilities response. Optionally, the MIHF  530  may be located outside of the AP  510  in the network (not shown). For example, the AP  510  may be connected to an access router (not shown) which may house the MIHF  530 . 
         [0029]    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). 
         [0030]    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. 
         [0031]    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.