The present invention is related to a wireless communication system. More particularly, the present invention is a method and system for switching a radio access technology (RAT) between wireless communication systems being connected to each other while implementing different RATs with a multi-mode wireless transmit/receive unit (WTRU).
Universal mobile telecommunication systems (UMTS) and wireless local area network (WLAN) technologies are widely used in current wireless communication systems. Since the coverage areas of UMTS and WLANs are often overlapped, an inter-networking of UMTS and WLAN networks has been developed. An inter-working WLAN (I-WLAN) is a WLAN with a connection to a UMTS core network so that the services provided by the UMTS may be forwarded through the I-WLAN.
Currently, the network selection of an I-WLAN requires that a WTRU scan for available WLAN systems using their service set identifiers (SSIDs). The scanning of SSIDs can be done either passively or actively. In passive scanning, the WTRU observes information broadcast from each WLAN and determines its availability according to the signal strength. In active scanning, the WTRU transmits a probe request containing a specific WLAN SSID and waits for confirmation of the availability from that WLAN.
These techniques, however, do not provide any indication of the WLAN (SSID) that provides access to UMTS based services. Several solutions have been devised including broadcasting of the home public land mobile network (PLMN) identification over the WLAN broadcast channel. However, such techniques are vulnerable to spoofing, (disruptive WLAN operators may broadcast the same SSIDs and PLMN ID), since WLAN SSIDs are not unique.
Therefore, the selection of a UMTS based I-WLAN for connecting to UMTS based services can be a problem due to the large number of WLAN networks (SSIDs) that the WTRU must choose from and the ease of using similar SSIDs by disruptive operators in order to direct the traffic toward their networks. Accordingly, there is a need for a method and system for providing an indication of WLANs (SSIDs) that provide access to UMTS based services.
The present invention is a method and system for switching a radio access technology (RAT) between wireless communication systems connected to each other while implementing different RATs with a multi-mode WTRU. A plurality of wireless communication systems are deployed with overlapping coverage areas wherein each wireless communication system implements different RATs and are connected to each other such that a service that is provided by one wireless communication system may be provided through the other wireless communication system. Each wireless communication system transmits an indication of the existence of an inter-working wireless communication system in a coverage area of each wireless communication system. The WTRU receives the indication and information regarding the inter-working wireless communication system. The WTRU then initiates a handoff to the inter-working wireless communication system using the received information, whereby the WTRU continues to receive the same services that the WTRU receives from the currently connected wireless communication system through the inter-working wireless communication system. The present invention helps reduce the time taken by the multi-mode WTRU to select and authenticate the inter-working wireless communication system.
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 drawing wherein:
Hereafter, the terminology “WTRU” includes but is not limited to a user equipment, a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, the terminologies “base station” and “access point (AP)” include but are not limited to a Node-B, a site controller or any other type of interfacing device in a wireless environment.
For convenience, the present invention is described with reference to a UTRAN and a WLAN. However, it should be noted that it is obvious to those skilled in the art that the present invention may be applied to any type of wireless communication system and further that there could be more than two different types of wireless communication networks.
Coverage areas of the wireless communication systems 110, 120 are overlapping with respect to each other. In a UTRAN-WLAN example, as is used herein, the coverage area of the WLAN 120 typically falls within the larger coverage area of a UTRAN cell 110. The WLAN 120 is connected to the UTRAN cell 110 so that the services provided within the UTRAN cell 110 may be forwarded to a multi-mode WTRU 102 through the WLAN 120. The WLAN 120 may therefore also be referred to as an I-WLAN, as explained above. A multi-mode WTRU 102 located in the overlapping area may access both types of wireless communication networks simultaneously, and may receive services provided by one network through the other network.
In accordance with the present invention, the UTRAN cell 110 sends an indication of the existence of any I-WLANs, or alternatively a list of service set identifiers (SSIDs) of the I-WLANs, located in the UTRAN cell 110 to the WTRU 102. The indication or the list of SSIDs may be transmitted as desired. For example, they may be broadcast via a broadcast control channel (BCCH) or may be sent via a dedicated control channel (DCCH). Where a system 100 is configured to transmit the indication or list over BCCHs, WTRUs may, but are not required to, provide their WLAN capability (i.e. whether or not they are capable of operating in a WLAN) upon connecting to the UTRAN cell 110 or upon establishment of a radio bearer. Where a system 100 is configured to transmit the indication or list over DCCHs, WTRUs are preferably required to provide their WLAN capability upon connecting to the UTRAN cell 110 or upon establishment of a radio bearer.
In accordance with a first embodiment, only an indication of the existence of any I-WLANs within the UTRAN cell 110 is transmitted. As mentioned above, the indication may be transmitted as desired, but is preferably transmitted over the cell's 110 broadcast control channel (BCCH) or over a dedicated control channel (DCCH). The WTRU 102 receives the indication and if a predetermined criteria for inter-system handoff (i.e. a predetermined criteria for handing over a WTRU 102 from the UTRAN cell 110 to the WLAN 120) is satisfied, the WTRU 102 requests the list of SSIDs from the UTRAN cell 110. It should be noted, of course, that the predetermined criteria may be any type of criteria and the evaluation of whether to actually perform an inter-system handoff may be evaluated by the WTRU 102 or by any of the network components of the network from which a handoff may occur, which in this case is a UTRAN.
Once the WTRU 102 receives the SSID list, the SSIDs are used, passively or actively, for scanning, association, and authentication of an appropriate AP within the I-WLAN 120. This scheme ensures that the WTRU 102 accesses the right WLAN AP that provides a connection to the UTRAN cell 110 and its 3GPP based services. Where the inter-system handoff criteria is met and there is an appropriate AP within the I-WLAN 120 to handoff to, the WTRU 102 is handed-off to the I-WLAN 120 and begins operating therein.
As an alternative, the WTRU 102 may request the list of SSIDs prior to evaluation of the inter-system handoff criteria in order to confirm whether there is an appropriate AP available prior to performing the evaluation.
In accordance with a second embodiment, the system 100 operates as mentioned above, but in this embodiment instead of first transmitting an indication of the existence of any I-WLANs within the UTRAN cell 110, the UTRAN cell 110 simply transmits the list of SSIDs. This may provide enhance performance where the number of SSIDs is not too high. Whether to implement the first or second embodiment is operator preference.
Each wireless communication system transmits an indication of the existence of an inter-working wireless communication system, optionally along with information of the alternative wireless communication system (including an identifier, frequency, etc), which implements a different RAT within the coverage area of each wireless communication system (step 202). The indication and/or the information may be broadcast to WTRUs or may be sent via a dedicated channel for the WTRUs. The WTRU receives the indication and/or the information through a currently connected wireless communication system (i.e. the wireless communication system to which the WTRU is currently connected) (step 204).
Alternatively, the indication and/or the information may be transmitted in response to a request message for the information or a capability report from the WTRU. In response, the currently connected wireless communication system sends an indication of availability of the inter-working wireless communication system and/or the information about the inter-working wireless communication system to the WTRU. In such case, the indication and/or the information may be transmitted via a DCCH to the WTRU.
After receiving the indication and/or the information, it is determined whether to initiate a handoff to the inter-working wireless communication system (step 206). As mentioned above, this determination may be made at the network or at the WTRU and may be based on any predetermined criteria, as desired. The handoff may be initiated by a user's request or may be initiated autonomously based on service requirements. The WTRU may display the availability of the inter-working wireless communication system on its display screen or provide an alarm alerting the user of the same. If it is determined to handoff the WTRU to the inter-working wireless communication system and if only the indication has been sent, the WTRU requests the information regarding the inter-working wireless communication system and receives it from the currently connected wireless communication system (step 208). If the information has been transmitted along with the indication or is simply sent without any indication, step 208 is skipped. The WTRU then initiates a handoff procedure using the received information (step 210).
In the context of a UTRAN-WLAN example as used herein, the information may be SSIDs of the I-WLANs, and optionally may further include a corresponding PLMN ID and the corresponding coordinates, (i.e., location), of each SSID. The WTRU initiates active or passive scanning for the identified WLANs after receiving the SSIDs of the I-WLANs. The WLAN scanning may be limited to WLANs identified by the received SSIDs.
Association with a particular WLAN AP may be based on channel quality measurements. If channel quality measurements from all WLANs are under a predefined threshold, the initial UTRAN connection is maintained. If an acceptable WLAN AP is found, the UTRAN may be notified of the cell change over the DCCH of the cell change. Connection security may be enabled by information such as wired equivalent privacy (WEP) information. The WTRU continues to scan for APs of common SSIDs of WLAN association and disassociation procedures. If an acceptable AP is not found, the WTRU may either scan for an alternate WLAN identified by a known SSID, or revert back to the UTRAN connection. In this case, an inter RAT cell change indication may be signaled. The choice to switch RATs may either be autonomous based on quality measurements within a predefined threshold or manually controlled by user input. After the RAT cell change, the WTRU continues to receive the same services that the WTRU receives from the currently connected wireless communication system through the alternative wireless communication system.
As mentioned above, different inter-working schemes may be used for connecting the I-WLAN to the UTRAN. For example, under the current wireless communication standards, the I-WLAN may be connected to the 3GPP system via a core network, (i.e., packet date gateway (PDG)), or via the UTRAN as a pipe. In the latter case, no new IP address is assigned in case of I-WLAN reselection, (handoff from the 3GPP system to I-WLAN). In the former case, (i.e., PDG based interworking), new procedures are used to allocate an IP address to the WTRU operating in the I-WLAN. These procedures are different than those used in the 3GPP system and thus may result in the assignment of a new IP address for the WTRU.
Although the elements in the Figures are illustrated as separate elements, these elements may be implemented on a single integrated circuit (IC), such as an application specific integrated circuit (ASIC), multiple ICs, discrete components, or a combination of discrete components and IC(s). 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. Furthermore, the present invention may be implemented in any type of wireless communication system.
This application claims the benefit of U.S. Provisional Application No. 60/552,561 filed Mar. 12, 2004, which is incorporated by reference as if fully set forth.
Number | Name | Date | Kind |
---|---|---|---|
3952610 | Hope et al. | Apr 1976 | A |
5611050 | Theimer et al. | Mar 1997 | A |
5666650 | Turcotte et al. | Sep 1997 | A |
5787347 | Yu et al. | Jul 1998 | A |
5826188 | Tayloe et al. | Oct 1998 | A |
5862480 | Wild et al. | Jan 1999 | A |
5930700 | Pepper et al. | Jul 1999 | A |
5946634 | Korpela | Aug 1999 | A |
5999816 | Tiedemann et al. | Dec 1999 | A |
6057782 | Koenig | May 2000 | A |
6061565 | Innes et al. | May 2000 | A |
6112093 | Nordlund | Aug 2000 | A |
6115608 | Duran et al. | Sep 2000 | A |
6128490 | Shaheen et al. | Oct 2000 | A |
6201968 | Ostroff et al. | Mar 2001 | B1 |
6243581 | Jawanda | Jun 2001 | B1 |
6304755 | Tiedemann et al. | Oct 2001 | B1 |
6353602 | Cheng et al. | Mar 2002 | B1 |
6385772 | Courtney | May 2002 | B1 |
6400265 | Saylor et al. | Jun 2002 | B1 |
6400951 | Vaara | Jun 2002 | B1 |
6470184 | Machida | Oct 2002 | B1 |
6487410 | Kontio et al. | Nov 2002 | B1 |
6546246 | Bridges et al. | Apr 2003 | B1 |
6591103 | Dunn et al. | Jul 2003 | B1 |
6594242 | Kransmo | Jul 2003 | B1 |
6600758 | Mazur et al. | Jul 2003 | B1 |
6615048 | Hayashi | Sep 2003 | B1 |
6643513 | Timonen et al. | Nov 2003 | B2 |
6668175 | Almgren et al. | Dec 2003 | B1 |
6680923 | Leon | Jan 2004 | B1 |
6718178 | Sladek et al. | Apr 2004 | B1 |
6721565 | Ejzak et al. | Apr 2004 | B1 |
6735433 | Cervantes | May 2004 | B1 |
6768726 | Dorenbosch et al. | Jul 2004 | B2 |
6771964 | Einola et al. | Aug 2004 | B1 |
6801772 | Townend et al. | Oct 2004 | B1 |
6826154 | Subbiah et al. | Nov 2004 | B2 |
6829481 | Souissi | Dec 2004 | B2 |
6832093 | Ranta | Dec 2004 | B1 |
6845238 | Muller | Jan 2005 | B1 |
6894988 | Zehavi | May 2005 | B1 |
6961561 | Himmel et al. | Nov 2005 | B2 |
6963745 | Singh et al. | Nov 2005 | B2 |
6973309 | Rygula et al. | Dec 2005 | B1 |
7006828 | Czaja et al. | Feb 2006 | B1 |
7009952 | Razavilar et al. | Mar 2006 | B1 |
7089008 | Back et al. | Aug 2006 | B1 |
7092710 | Stoter et al. | Aug 2006 | B1 |
7092743 | Vegh | Aug 2006 | B2 |
7096015 | Bridges et al. | Aug 2006 | B2 |
7133384 | Park et al. | Nov 2006 | B2 |
7146130 | Hsu et al. | Dec 2006 | B2 |
7146636 | Crosbie | Dec 2006 | B2 |
7149521 | Sundar et al. | Dec 2006 | B2 |
7155225 | Segal et al. | Dec 2006 | B2 |
7164923 | Tsunomoto et al. | Jan 2007 | B2 |
7181218 | Ovesjo et al. | Feb 2007 | B2 |
7200401 | Hulkkonen et al. | Apr 2007 | B1 |
7206318 | Keller | Apr 2007 | B2 |
7254119 | Jiang et al. | Aug 2007 | B2 |
7263367 | Sabot | Aug 2007 | B1 |
7283507 | Buckley et al. | Oct 2007 | B2 |
7376098 | Loeffler et al. | May 2008 | B2 |
7418267 | Karaoguz | Aug 2008 | B2 |
7486635 | Okanoue et al. | Feb 2009 | B2 |
7508799 | Sumner et al. | Mar 2009 | B2 |
20020022478 | Iwao | Feb 2002 | A1 |
20020024937 | Barnard et al. | Feb 2002 | A1 |
20020025810 | Takayama et al. | Feb 2002 | A1 |
20020032034 | Tiedemann et al. | Mar 2002 | A1 |
20020032748 | Myojo | Mar 2002 | A1 |
20020068570 | Abrol et al. | Jun 2002 | A1 |
20020082044 | Davenport | Jun 2002 | A1 |
20020120749 | Widegren et al. | Aug 2002 | A1 |
20020136226 | Christoffel et al. | Sep 2002 | A1 |
20020146021 | Schwartz et al. | Oct 2002 | A1 |
20020147008 | Kallio | Oct 2002 | A1 |
20020147012 | Leung et al. | Oct 2002 | A1 |
20020180582 | Nielsen | Dec 2002 | A1 |
20030002525 | Grilli et al. | Jan 2003 | A1 |
20030003933 | Deshpande et al. | Jan 2003 | A1 |
20030012156 | Fukuda | Jan 2003 | A1 |
20030013443 | Willars et al. | Jan 2003 | A1 |
20030013463 | Yen | Jan 2003 | A1 |
20030045322 | Baer et al. | Mar 2003 | A1 |
20030046546 | Endo | Mar 2003 | A1 |
20030080996 | Lavin et al. | May 2003 | A1 |
20030081567 | Okanoue et al. | May 2003 | A1 |
20030092444 | Sengodan et al. | May 2003 | A1 |
20030100307 | Wolochow et al. | May 2003 | A1 |
20030114158 | Soderbacka et al. | Jun 2003 | A1 |
20030118015 | Gunnarsson et al. | Jun 2003 | A1 |
20030119480 | Mohammed | Jun 2003 | A1 |
20030123479 | Lee et al. | Jul 2003 | A1 |
20030125028 | Reynolds | Jul 2003 | A1 |
20030142641 | Sumner et al. | Jul 2003 | A1 |
20030148777 | Watanabe et al. | Aug 2003 | A1 |
20030148786 | Cooper et al. | Aug 2003 | A1 |
20030149875 | Hosaka | Aug 2003 | A1 |
20030163558 | Cao et al. | Aug 2003 | A1 |
20030174667 | Krishnamurthi et al. | Sep 2003 | A1 |
20030179726 | Forssell et al. | Sep 2003 | A1 |
20030206533 | Charas | Nov 2003 | A1 |
20030208602 | Bhalla et al. | Nov 2003 | A1 |
20040002343 | Brauel et al. | Jan 2004 | A1 |
20040014474 | Kanada | Jan 2004 | A1 |
20040018829 | Raman et al. | Jan 2004 | A1 |
20040028009 | Dorenbosch et al. | Feb 2004 | A1 |
20040029587 | Hulkkonen et al. | Feb 2004 | A1 |
20040033805 | Verma et al. | Feb 2004 | A1 |
20040058717 | McDonnell et al. | Mar 2004 | A1 |
20040063426 | Hunkeler | Apr 2004 | A1 |
20040068571 | Ahmavaara | Apr 2004 | A1 |
20040090937 | Chaskar et al. | May 2004 | A1 |
20040092259 | Blanc et al. | May 2004 | A1 |
20040100913 | Kalliokulju et al. | May 2004 | A1 |
20040103204 | Yegin | May 2004 | A1 |
20040105434 | Baw | Jun 2004 | A1 |
20040114553 | Jiang et al. | Jun 2004 | A1 |
20040127241 | Shostak | Jul 2004 | A1 |
20040157600 | Stumpert et al. | Aug 2004 | A1 |
20040176103 | Trossen et al. | Sep 2004 | A1 |
20040185845 | Abhishek et al. | Sep 2004 | A1 |
20040203748 | Kappes et al. | Oct 2004 | A1 |
20040203773 | Balasubramanian et al. | Oct 2004 | A1 |
20040203873 | Gray | Oct 2004 | A1 |
20040203890 | Karaoguz et al. | Oct 2004 | A1 |
20040264410 | Sagi et al. | Dec 2004 | A1 |
20050025164 | Kavanagh et al. | Feb 2005 | A1 |
20050047373 | Kojima | Mar 2005 | A1 |
20050059410 | Trossen et al. | Mar 2005 | A1 |
20050064877 | Gum et al. | Mar 2005 | A1 |
20050070289 | Vestama et al. | Mar 2005 | A1 |
20050090259 | Jain et al. | Apr 2005 | A1 |
20050107093 | Dowling | May 2005 | A1 |
20050176445 | Qu et al. | Aug 2005 | A1 |
20050177733 | Stadelmann et al. | Aug 2005 | A1 |
20050202791 | Krause | Sep 2005 | A1 |
20050288019 | Park et al. | Dec 2005 | A1 |
20060004643 | Stadelmann et al. | Jan 2006 | A1 |
20060052100 | Almgren | Mar 2006 | A1 |
20060084440 | Bakri | Apr 2006 | A1 |
20060291455 | Katz et al. | Dec 2006 | A1 |
20060293053 | Zanaty | Dec 2006 | A1 |
20070093201 | Hsu et al. | Apr 2007 | A1 |
20070112948 | Uhlik | May 2007 | A1 |
20070208864 | Flynn et al. | Sep 2007 | A1 |
20070217366 | Sagi et al. | Sep 2007 | A1 |
20070259653 | Tang et al. | Nov 2007 | A1 |
20080101291 | Jiang et al. | May 2008 | A1 |
20080240036 | Liu et al. | Oct 2008 | A1 |
Number | Date | Country |
---|---|---|
0852448 | Jul 1998 | EP |
1081909 | Mar 2001 | EP |
1178646 | Feb 2002 | EP |
1213941 | Jun 2002 | EP |
1257141 | Nov 2002 | EP |
1278143 | Jan 2003 | EP |
1395076 | Mar 2004 | EP |
2322051 | Aug 1998 | GB |
2377130 | Dec 2002 | GB |
2391432 | Feb 2004 | GB |
2000-092541 | Mar 2000 | JP |
2001-258058 | Sep 2001 | JP |
2003-264868 | Sep 2003 | JP |
2000-0060796 | Oct 2000 | KR |
9636190 | Nov 1996 | WO |
0004718 | Jan 2000 | WO |
0060895 | Oct 2000 | WO |
0065802 | Nov 2000 | WO |
0128154 | Apr 2001 | WO |
0131963 | May 2001 | WO |
0135585 | May 2001 | WO |
0158177 | Aug 2001 | WO |
0169858 | Sep 2001 | WO |
0211358 | Feb 2002 | WO |
0213157 | Feb 2002 | WO |
0230133 | Apr 2002 | WO |
02062094 | Aug 2002 | WO |
02080605 | Oct 2002 | WO |
03003639 | Jan 2003 | WO |
03024144 | Mar 2003 | WO |
03045095 | May 2003 | WO |
03054721 | Jul 2003 | WO |
03079660 | Sep 2003 | WO |
2004006482 | Jan 2004 | WO |
2004089021 | Oct 2004 | WO |
2004100452 | Nov 2004 | WO |
Number | Date | Country | |
---|---|---|---|
20050202823 A1 | Sep 2005 | US |
Number | Date | Country | |
---|---|---|---|
60552561 | Mar 2004 | US |