Abstract:
A method and system for reporting short message (SM) capability over an IP multimedia subsystem (IMS) using a session initiation protocol (SIP) are disclosed. A wireless transmit/receive unit (WTRU) registers with a core network and sends a message indicating its SM capability via the IMS to the core network. The core network then updates the WTRU capabilities based on the message and routes an SM to the WTRU via the IMS.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. provisional application No. 60/705,911 filed Aug. 5, 2005, which is incorporated by reference as if fully set forth. 
    
    
     FIELD OF INVENTION 
     The present invention is related to wireless communication systems. More particularly, the present invention is related to a method and system for reporting short message (SM) capability via an IP multimedia subsystem (IMS). 
     BACKGROUND 
     At initiation of a wireless communication session between a wireless transmit/receive unit (WTRU) and a core network, the WTRU requests for a signaling connection in an attach procedure according to third generation partnership project (3GPP) standards. Currently, a network capability to support a short message service (SMS) via dedicated channels and global packet radio service (GPRS) channels are reported in a network capability information element (IE). 
     However, there is no means for reporting WTRU SM capability via an IMS. As a consequence, the core network is unaware of the WTRU SM capability and an SM may not be routed to the WTRU via an IMS. Since the current wireless communication standards mandate that the WTRU indicate the preferred mode of operation (in terms of delivery of SMS), the WTRU should indicate the delivery of SMS over a GSM network or a GPRS based network. However, for example, if the WTRU is operating on a GPRS network and the preferred setting is on a GSM network, SMS messages may be lost. The same problem also occurs when the WTRU operates in a GSM mode while the preferred operation is GPRS delivery. Therefore, it is desirable to provide a means for the WTRU to report the SM capability over the IMS to the core network. 
     SUMMARY 
     The present invention is related to a method and system for reporting an SM capability over an IMS using a session initiation protocol (SIP). A WTRU registers with a core network and sends a message indicating its SM capability via the IMS to the core network. The core network then updates the WTRU capabilities based on the message and routes an SM to the WTRU via the IMS. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a wireless communication system that supports messaging services via an IMS in accordance with the present invention. 
         FIG. 2  is a flow diagram of a process for reporting the SM capability of the WTRU during an attach procedure in accordance with the present invention. 
         FIG. 3A  shows a conventional network capability information element (IE). 
         FIG. 3B  shows a network capability IE configured in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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, or any other type of device capable of operating in a wireless environment. 
     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. 
       FIG. 1  shows a block diagram of a wireless communication system  100  that supports messaging services over an IMS  116  using an SIP in accordance with the present invention. The system  100  includes a core network and one or more radio access networks (RANs) which may implement different radio access technologies (RATs). The RANs include, but are not limited to, a global standards for mobile communication (GSM) RAN  102 , a third generation (3G) RAN  104  and an interworking wireless local area network (I-WLAN)  106 . The core network includes a short message service (SMS) gateway mobile switching center (SMS-GMSC)/interworking mobile switching center (IW-MSC)  120 , a home location register (HLR)  122 , a short message IP gateway (SM-IP-GW)  118 , a GPRS support node (GSN)  114 , a mobile switching center (MSC)  112 , an IMS  116 , and a visitor location register (VLR)  124 . 
     The GSM RAN  102  is connected to the MSC  112  for circuit switching services and the 3G RAN  104  is connected to the GSN  114  for packet switching services. The I-WLAN  106  has an IP access capability to the IMS  116 , (via a packet data gateway (PDG) and/or a WLAN access gateway (WAG)), for IP services through the core network. 
     A service center  126  sends a short message (SM)  140  to the SMS-GMSC/IW-MSC  120 . The SMS-GMSC/IW-MSC  120  is a gateway between the service center  126  and the MSC  112 , the GSN  114  and/or the SM-IP-GW  118 . The SMS-GMSC/IW-MSC  120  accepts a WTRU-terminated SM or a WTRU-originated SM and delivers the SM  140  to the MSC  112 , the GSN  114  or the SM-IP-GW  118 . When the WTRU  130  is connected to the 3G RAN  104 , the SM  140  may be routed from the SMS-GMSC/IW-MSC  120  to the 3G RAN  104  via the GSN  114 . When the WTRU  130  is connected to the GSM RAN  102 , the SM  140  may be routed from the SMS-GMSC/IW-MSC  120  to the GSM RAN  102  via the MSC  112 . When the WTRU  130  is registered with the SM-IP-GW  118 , the SM  140  may be routed via the SM-IP-GW  118  and the IMS  116  using an SIP, which will be explained in detail hereinafter. 
     The SM  140  may be an SMS message, (e.g., text only or text plus video message), a multimedia message service (MMS) message, an instant message service message, or the like. 
     Before originating or receiving the SM  140  over an IP network, such as the IMS  116 , the WTRU  130  must register with an appropriate SM-IP-GW  118 . The SM-IP-GW  118  communicates between the WTRU  130  and the SMS-GMSC/IW-MSC  120 , and provides protocol interworking for delivery of the SM  140  between the WTRU  130  and the SMS-GMAC/IW-MSC  120 . The SM-IP-GW  118  maintains a registration status of WTRUs  130 . Upon registration, the SM-IP-GW  118  informs the HLR  122  that the WTRU  130  has successfully registered with the SM-IP-GW  118 . 
     Upon receipt of the SM  140  from the service center  126 , the SMS-GMSC/IW-MSC  120  interrogates the HLR  122  to retrieve routing information for the WTRU  130 . When the WTRU  130  is connected to the GSM RAN  102  or the 3G RAN  104 , the HLR  122  returns the address of the MSC  112  or the GSN  114 , respectively. If the WTRU  130  is registered with the SM-IP-GW  118 , the HLR  122  returns the address of the SM-IP-GW  118 . 
     In accordance with the present invention, the SM  140  is routed to the WTRU  130  over the IMS  116  using an SIP. The WTRU  130  is registered with the SM-IP-GW  118  and the registration status is recorded in the HLR  122 . When the SMS-GMSC/IW-MSC  120  interrogates the HLR  122  for routing information, the HLR  122  returns the address of SM-IP-GW  118 , (rather than the address of an appropriate MSC  112  or SGSN  114 ), to the SMS-GMSC/IW-MSC  120 . The SMS-GMSC/IW-MSC  120  then delivers the SM  140  to the SM-IP-GW  118  using the obtained address of the SM-IP-GW  118 . The SM-IP-GW  118  then forwards the SM  140  to the IMS  116 . 
     The IMS  116  then forwards the SM  140  either to the 3G RAN  104  via the GSN  114  or to the I-WLAN  106 , depending on the current connection of the WTRU  130 . When the WTRU  130  is connected to the 3G RAN  104 , the SM  140  is routed from the SM-IP-GW  118  to the 3G RAN  104  via the IMS  116  and the GSN  114  using an SIP. When the WTRU  130  is connected to the I-WLAN  106 , the SM  140  is routed from the SM-IP-GW  118  to the I-WLAN  106  via the IMS  116  using an SIP. 
     In accordance with the present invention, the WTRU  130  reports its SM capability via an IMS using an SIP to the core network, (preferably a serving GPRS support node (SGSN)), to be recorded in the HLR  122 . The reporting is preferably performed during an attach procedure, which will be described in detail hereinafter. The core network may also inform the WTRU  130  of the network&#39;s capability to support the SMS over an IMS. 
       FIG. 2  is a flow diagram of a process  200  for reporting WTRU SM capabilities via an IMS in accordance with the present invention. The WTRU  130  may be a multi-mode WTRU including multiple radio units for supporting multiple RATs, such as a GSM air interface, an I-WLAN air interface, a 3G air interface, or the like. Upon power up at step  202 , the WTRU  130  sends a radio resource control (RRC) connection request message to a radio network controller (RNC)  113  of a 3G RAN to establish a connection to the 3G RAN  104  (step  204 ). The RNC  113  performs an admission control based on predetermined factors, such as availability of resources, or the like (step  206 ). If the RNC  113  decides to admit the WTRU  130 , the RNC  113  sends an RRC connection setup message to the WTRU  130  (step  208 ). The WTRU  130  then sends an RRC connection complete message to the RNC  113  (step  210 ). 
     The WTRU  130  then sends an attach request message to the RNC  113  in order to receive 3G services (step  212 ). In accordance with the present invention, the information regarding the SM capability of the WTRU via an IMS is sent using a network capability IE along with the attach request message. The RNC  113  selects an SGSN  114  to serve the WTRU  130  and forwards the attach request message to the selected SGSN  114  along with the SM capability information (step  214 ). Authentication and security functions are performed between the WTRU  130  and the SGSN  114  (step  216 ). Once the WTRU  130  is authenticated at step  218 , the SGSN  114  sends an update WTRU capability message to an HLR  122  to update WTRU capabilities (step  220 ) and sends an attach accept message to the RNC  113 , which forwards it to the WTRU  130  (steps  222 ,  224 ). Once the WTRU capability is updated at the HLR  122  and the WTRU  130  is registered with the SM-IP-GW  118 , the SM  140  may be routed to the WTRU  130  via the IMS  116 . The core network, (preferably an SGSN), may also send information regarding the network&#39;s capability of supporting SMS data delivery over an IMS. The information may be sent along with the attach accept message or any other message. 
       FIG. 3A  shows a conventional network capability IE. The network capability IE includes information bits indicating an SM capability via dedicated channels and an SM capability via GPRS channels, but not an SM capability via an IMS. 
       FIG. 3B  shows an example of a network capability IE configured in accordance with the present invention. The network capability IE shown in  FIG. 3B  includes new information bits  302  indicating the SM capability via an IMS. The new information bits for the SM capability via an IMS may indicate capability of supporting SMS, IMS, MMS, or the like. A similar network capability IE may be used for the core network to report the network&#39;s capability to support SMS via an IMS. 
     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.