Abstract:
A method enabling a wireless remote terminal (UE) to access a universal mobile telecommunication system (UMTS) through a wireless local area network (WLAN) wherein UMTS services are transmitted to a format converter from a UMTS transceiver and the format converter changes the format of received messages to a WLAN format before transmission to the UE which is operating in the WLAN mode.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority from Application No. 60/399,787; filed on Jul. 31, 2002 which application is incorporated herein by reference. 

   FIELD OF INVENTION 
   The present invention relates to wireless communications. More particularly the invention deals with WLAN-UMTS interworking. 
   BACKGROUND 
   Subscribers, such as mobile stations (UEs), to a universal mobile telecommunication system (UMTS) which are operating under a wireless local area network (WLAN) environment and desire to access the UMTS, can incur a significant increase in costs when accessing UMTSs in those areas where the UMTS system access would be of substantial cost. An alternative for accessing a UMTS without incurring such substantial costs is desirable. 
   SUMMARY 
   The present invention provides a less expensive alternative for accessing a UMTS without incurring such substantial costs. The composite systems of the present invention comprises a UMTS system underlayed by a WLAN system. The UMTS is provided with a transceiver acting as a UMTS radio front-end for a UMTS subscriber operating in a WLAN environment. The interface between the UMTS system and the end user (UE) is obtained through the WLAN interface. 
   The WLAN system converts received UMTS messages and/or traffic for pre-registered users into a format suitable for WLAN transmission to be delivered to users operating in WLAN environments. In addition, the WLAN converts transmitted messages and traffic flows into UMTS formats which is then transmitted to the UMTS system by way of the UMTS transceiver supporting the WLAN system. The WLAN users gain access to the UMTS system through a UMTS air interface employing a translator. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
     The present invention will be understood from a consideration of the accompanying description and drawings in which like elements are designated by like numerals and, wherein: 
       FIG. 1  is a diagram of a UMTS system underlayed by a WLAN system. 
       FIGS. 2 and 3  are diagrams showing the message utilized for the WLAN-UMTS interworking in accordance with the apparatus and methods of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows an arrangement  10  useful in explaining the interworking between a UMTS system  12  and WLAN system  14 . The arrangement of  FIG. 1  will be described in conjunction with the technique for delivery of UMTS based services when a mobile station such as a remote terminal is served by the WLAN system. 
   Making reference to  FIG. 2 , and, where appropriate,  FIG. 1 , there is shown an arrangement similar to that of  FIG. 1 . 
   Only one mobile station  24  is shown for purposes of simplicity, it being understood that a plurality of such mobile terminals are serviced by the WLAN  14 . Although the mobile station remote terminal (UE)  24  may also be a dual-mode terminal capable of communicating with a WLAN and a UMTS, for purposes of the present invention, a WLAN-capable terminal  24  is utilized. 
   User terminal (UE)  24 , through its WLAN capability  24   a , registers with WLAN  14 , by communicating with an access point (AP) of the WLAN (see  FIG. 1 ) at step S 1 . WLAN  14 , at step S 2 , then registers the user identification (ID) for the UMTS service watch, communicating with UMTS transceiver  18 . UMTS transceiver  18  is tuned for any services addressed to registered users&#39; identifications (IDs). When a UMTS service, such as a page, short message service (SMS), multimedia message service (MMS) or the like is to be delivered, UMTS  12  transfers such a service, in the example given a page message, at step S 3 , the page message being delivered to UMTS transceiver  18 . UMTS transceiver  18 , at step S 4 , typically from a radio tower  26 , transmits the page message over UMTS air interface  28  to a receiving radio tower  30 , to format converter  16  which, at step S 5 , converts the present (UMTS) format into a WLAN message format and, at step S 6 , communicates the page message, in WLAN message format, to WLAN  14 . WLAN  14 , at step S 7 , delivers the page message to mobile terminal  24 . An acknowledgement is relayed from terminal  24 , at step S 8 , to WLAN  14 , the acknowledgement being transferred to format converter  16  at step S 9  and from there to UMTS transceiver  18 , at step S 10 , and finally to UMTS  12 , at step S 11 . 
     FIG. 3  shows a terminal  24  similar to that shown in  FIG. 2 , which, through its WLAN capability  24   a , registers with WLAN  14 , at step S 1 . The WLAN  14 , at step S 2 , forwards the user registration to format converter  16  which, at step S 3 , changes the format into a UMTS message format and, at step S 4 , provides a UMTS package switched (PS) UMTS attachment directed to the UMTS transceiver  18 . UMTS transceiver  18  transfers the UMTS PS attached to UMTS  12 , at step S 5 . 
   The PS attach completed message is transferred from UMTS  12  to UMTS transceiver  18 , at step S 6 , and from UMTS transceiver  18  to format converter  16 , at step S 7 . Format converter  16 , at step S 8 , changes the format of the PS attach into a WLAN message format and, at step S 9 , conveys the message to WLAN  14  which, at step S 10 , provides the message to mobile terminal  24 . Acknowledgement from terminal  24  to WLAN  14  occurs at step S 11 , from WLAN  14  to format converter  16 , at step S 12 , from format converter  16  to UMTS transceiver  18 , at step S 13  and the UMTS transceiver  18  to UMTS  12 , at step S 14 , thereby completing the acknowledgment.