Method and apparatus for wlan-umts interworking employing umts air interface

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.

The article "Roaming und Handover zwischen UTTTS und Funk-LAN" of Ostrowski F. (ISSN: 0027-707X) discloses a handover procedure between WLAN and UMTS networks. By the use of Home Agents and Gore of Addresses a mobile Terminal can migrate from UMTS to WLAN network while continuing a pocket switched communication.

[0006] 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.

<b>[0007]</b> 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: <ul id="ul0001" list-style="none" compact="compact"><li>Figure 1 is a diagram of a UMTS system underlayed by a WLAN system.</li><li>Figures 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.</li></ul>

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 shows an arrangement 10 useful in explaining the interworking between a UMTS system 12 and WLAN system 14. The arrangement of Figure 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.

[0014] Making reference to Figure 2, and, where appropriate, Figure 1, there is shown an arrangement similar to that of Fig. 1.

[0015] 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 the present invention, a WLAN-capable terminal 24 is utilized.

[0016] User terminal (UE) 24, through its WLAN capability 24A, registers with WLAN 14, at step S1. WLAN 14, at step S2, 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' 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 S3, the page message being delivered to UMTS transceiver 18. UMTS transceiver 18, a step S4, 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 S5, converts the present (UMTS) format into a WLAN message format and, at step S6, communicates the page message, in WLAN message format, to WLAN 14. WLAN 14, at step S7, delivers the page message to mobile terminal 24. An acknowledgement is relayed from terminal 24, at step S8, to WLAN 14, the acknowledgement being transferred to format converter 16 at step S9 and from there to UMTS transceiver 18, at step S10, and finally to UMTS 12, at step S11. Figure 3 shows a terminal 24 similar to that shown in Fig. 2, which, through its WLAN capability 24A, registers with WLAN 14, at step S1. The WLAN 14, at step S2, forwards the user registration to format converter 16 which, at step S3, changes the format into a UMTS message format and, at step S4, 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 S5. The PS attach completed message is transferred from UMTS 12 to UMTS transceiver 18, at step S6, and from UMTS transceiver 18 to format converter 16, at step S7. Format converter 16, at step S8, changes the format of the PS attach into a WLAN message format and, at step S9, conveys the message to WLAN 14 which, at step S10, provides the message to mobile terminal 24. Acknowledgement from terminal 24 to WLAN 14 occurs at step S11, from WLAN 14 to format converter 16, at step S12, from format converter 16 to UMTS transceiver 18, at step S13 and the UMTS transceiver 18 to UMTS 12, at step S14, thereby completing the acknowledgment.