System and method for integrating WLAN and 3G

A method and system for providing ubiquitous coverage and seamless connectivity for devices which support Internet access via third generation (3G) cellular and IEEE 802.11 wideband local area network (WLAN) technologies, irrespective of which radio access technology is available.

FIELD OF INVENTION

The present invention relates to the field of wireless communications and, more particularly, the present invention relates to the integration of wireless local area networks (WLAN) and cellular networks.

BACKGROUND

Currently, dual mode devices are envisioned to support Internet access via a wide array of different radio access technologies. The goal is to provide ubiquitous coverage and seamless connectivity irrespective of which radio access technology is available.

FIG. 1shows a conventional dual mode mobile terminal system100including a dual mode mobile terminal105. The two modes to which “dual mode” refers are a network which complies with IEEE 802.11 and a network which complies with one or more of the Third Generation (3G) standards. The dual mode mobile terminal105communicates with the Internet110via (1) an IEEE 802.11 access point/router equipment115over an IEEE 802.11 air interface, or (2) a 3G universal terrestrial radio access network (UTRAN) base station120via a 3G air interface.

A difficulty associated with such a conventional system100is that, due to architectural differences, there is no common control entity to manage the physical handover process between the IEEE 802.11 and 3G radio networks. This results in a complex association between the handover control functions of each network. For example, the coordination and logic required to transfer the radio connection from the IEEE 802.11 network to the 3G network is significantly different from what is required to transfer the radio connection from the 3G network to the IEEE 802.11 network. Note that the handover in this sense can also be viewed as cell reselection or re-association. What is needed is a system and method for seamlessly and simply facilitating wireless connectivity between two different radio access technologies.

Another problem is that 802.11 access devices require service from 802.11 access points that have dedicated terrestrial trunks to the Internet. When an 802.11 access point is unavailable, Internet services are not provided to the 802.11 access device. Since 802.11 access points are generally not provisioned to provide ubiquitous coverage the mobile user will often have access to Internet services. Further, dedicated terrestrial links providing Internet connectivity to the 802.11 access points in certain deployment scenarios are expensive to install and maintain. In these cases, an alternative to the terrestrial link is needed.

SUMMARY

A cellular terminal that incorporates 802.11 access technology (e.g., association/re-association processes) provides 3G connectivity for 802.11 access devices. The present invention allows a wireless device to have wireless service/connectivity over different types of wireless radio access technology, which allows for mobility and ubiquitous coverage for Internet services.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Although the preferred embodiments are described in conjunction with a preferred system that uses IEEE 802.11 and 3G radio access technologies, the invention in its broad form is envisaged to be also applicable to other systems of transmission, without limitation.

FIG. 2shows a system150including an integrated IEEE 802.11 terminal130(hereinafter terminal130). The terminal130includes an IEEE 802.11 Access Point (AP)/router132(hereinafter AP132) and a 3G Wireless Transmit/Receive Unit (WTRU)134(hereinafter WTRU134), which are coupled to each other via an interface136. The terminal130is coupled with a 3G UTRAN138(hereinafter UTRAN138) via a 3G air interface140, and is coupled with an IEEE 802.11 WLAN access device142(hereinafter access device142) via an IEEE 802.11 air interface144.

Hereafter, a wireless transmit/receive unit (WTRU) includes but is not limited to a user equipment, mobile station, fixed or mobile subscriber unit, pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, a base station includes but is not limited to a base station, Node-B, site controller, access point or other interfacing device in a wireless environment.

Essentially, system150applies two air interfaces, e.g., a WLAN AP and a 3G user equipment (UE), in series rather than in parallel. This simplifies integration since each air interface is logically independent (i.e., a common control entity is not required) and thus is not affected by the other (i.e., each air interface runs as if the other air interface does not exist). For example, there is no need to coordinate handovers between each radio access technology (e.g., IEEE 802.11 to 3G, or vice versa). Handovers over the 3G air interface140can be handled transparently to the IEEE 802.11 air interface144. In the case of an integrated AP 132/WTRU134, a WLAN connection is established, which may dynamically cause the 3G connection to be established and/or allocate physical resources.

System150implements a standard IEEE 802.11 association or re-association process for transition from the access device142to a 3G cellular connection via the 3G air interface140. A re-association is used when the AP is part of the same Extended Service Set (ESS) known by the Service Set Identifier (SSID) realized during active or passive scanning process. Otherwise, a different SSID is recognized and a new association is initiated. The access device generates an association request (AR) that includes a Basic Service Set ID (BSSID) (i.e., MAC ID) and an SSID normally corresponding to a group of access points that are part of an ESS. Each AP replies with an association response that includes an association ID (i.e., logical connection ID) unique to that AP.

The access device142realizes the terminal130by standard IEEE 802.11 active or passive scanning methods. When using passive scanning, the access device142receives one or more beacon transmissions from one or more APs. A beacon channel identifies certain types of system information, such as the access point's BSSID and SSID. When using active scanning, a level of security is provided whereby the AP's SSID is not signaled on the beacon channel. The access device142generates a probe request indicating a preconfigured SSID of an AP. APs which receive the probe request confirm reception with a probe response when they have the preconfigured SSID.

There are several alternative embodiments for operating the terminal130in accordance with the present invention. In one alternative embodiment, dynamic allocation is implemented, whereby the standard IEEE 802.11 logic (e.g., association, re-association, disassociation) is used to establish or release the 3G connection. In another alternative embodiment, a 3G connection is established in advance (i.e., continuously) with either dynamically or permanently allocated physical resources.

As will be described in detail hereinafter, when a mobile user travels outside of an IEEE 802.11 WLAN coverage area, which provides certain services such as a dedicated terrestrial termination to the Internet, the terminal130provides access to the Internet. The access device142will automatically re-associate with the terminal130without requiring any customized software or hardware. Alternatively, the access device142may always use the terminal130, thus eliminating the need to provision one or more IEEE 802.11 APs with dedicated terrestrial Internet terminations.

FIG. 3shows a system200operating in accordance with one preferred embodiment of the present invention. The system200includes an integrated IEEE 802.11 terminal220(hereinafter terminal220) that facilitates seamless Internet connectivity between the different radio access technologies. The system200further includes an IEEE 802.11 WLAN access device205(hereinafter access device205), an IEEE 802.11 AP/router210(hereinafter AP210), the Internet215and a 3G UTRAN225(hereinafter UTRAN225). The terminal220includes an IEEE 802.11 AP/router230(hereinafter AP230) and a 3G WTRU235(hereinafter WTRU235), which are coupled to each other via an interface238. The terminal220is coupled with the 3G UTRAN225(hereinafter UTRAN225) via a 3G air interface250, and is coupled with the access device205via an IEEE 802.11 air interface245. The access device205is initially associated with the AP210via a path240. The terminal220is activated to establish an 3G air interface connection to an external network, such as the Internet215, by either manually turning on the access device205and enabling the Internet access feature (e.g., by a user request/input) or by automatically detecting the IEEE 802.11 access device association procedures. Standard IEEE 802.11 authentication and data encryption security features may be incorporated to control unauthorized access. The access device205may be a laptop, a personal digital assistant (PDA) or the like.

The 3G cellular connection is initiated by the WTRU235. The service type, packet domain, and other connection aspects are either preconfigured or manually requested by the user. The WTRU235and the UTRAN225establish a normal 3G connection to the Internet215upon either manual or automatic activation. Once established, the 3G cellular connection is transparent to the access device205. The access device205realizes the terminal220by standard IEEE 802.11 active or passive scanning methods.

Upon disassociation of the access device205or upon timeout of a preconfigured inactivity timer, the 3G cellular connection may be released by the terminal220in response to an automatic detection of the IEEE 802.11 access device disassociation procedure or automatic timeout or an inactivity timer. Alternatively, the 3G cellular connection may be released manually by user intervention in response to turning off the device or disabling the Internet access feature. In either case, the 3G air interface connection to the Internet215is released.

The access device205initiates either the association or re-association to the integrated terminal220via path245. The terminal220recognizes the access device205and establishes a 3G cellular radio connection via 3G air interface250.

A similar process is invoked for association or re-association from the terminal220to the standard AP210. Upon disassociation with the terminal220via IEEE 802.11 air interface245, or timeout of the inactivity timer or re-association within the same ESS, the connection to the UTRAN225via the 3G air interface250is released.

In one embodiment, the terminal220may establish a permanent connection to the UTRAN225to allow for “always on” services, e.g., wireless local loop (WLL), or facilitate a fast handover between the IEEE 802.11 service provider and the 3G cellular service providers. In this case, the 3G radio access network (RAN) connection is pre-established. The terminal220provides a continuous IEEE 802.11 access link. The access device205invokes the normal IEEE 802.11 active/passive scanning, and association/re-association processes.

This embodiment may be implemented such that the 3G RAN user data radio bearers are pre-established prior to IEEE 802.11 association with the terminal220, or upon detection of the access device205. 3G radio resources are either dynamically allocated by the 3G Radio Network Controller (RNC) on an as needed basis realized by the existence of transmission data or statically assigned for the period during which the access device is associated with the AP. The IEEE 802.11 and 3G coverage areas may partially overlap for contiguous coverage. Alternatively, the IEEE 802.11 and 3G coverage may be physically disjoint. There is no limit to the distance between coverage areas. The IEEE 802.11 and 3G coverage areas may be co-located to provide redundancy. In general, IEEE 802.11 service areas are “hot spots” (i.e., “islands”). Service is provided between these IEEE 802.11 service areas by one or more 3G cellular systems. Each 3G service area will likely overlap at least one of the IEEE 802.11 service area.

FIG. 4shows a system300for routing several IP data services in accordance with one embodiment of the present invention. System300includes an integrated IEEE 802.11 terminal305which is similar to terminal220except that it incorporates an Internet Protocol (IP) application processor330(hereinafter processor330) with the AP230and supports a plurality of IEEE 802.11 WLAN access devices310,315and a 3G UTRAN320(hereinafter UTRAN320). A common set of physical channels provides for transmission over an 3G air interface325connecting the terminal305to the UTRAN320. IP data is provided to the processor330which implements layer3IP switching within the terminal305, which allows for several independent access devices and/or IP applications within the terminal305to be supported simultaneously.

In systems150and200(FIGS. 2 and 3), IP router functionality is not implemented. In system300, the AP230switches IP data packets to either the external 802.11 access devices310,315, or to IP applications internal to the integrated terminal305. Functionality is added to the terminal305not to the AP230. For example, the terminal305may be the 3G mobile cellular terminal that has the ability to provide internet services (the “IP application”). This can still be accomplished, even when supporting Internet connectivity for one or more 802.11 access devices. Based on an IP address, data is routed by the AP230to and from multiple IEEE 802.11 WLAN access devices310,315and IP applications330internal to the terminal305.

The terminal305may be associated with several access devices310,315(laptops, PDAs, etc.) at one time. Association and disassociation of each access device310,315is an independent process. Each access device310,315may have either common or independent 3G RAN connections and/or radio bearers supported by common radio resources. An Internet Protocol (IP) router function within the terminal305allows several independent IP data streams to be supported by a common set of physical channels assigned to the 3G radio connection.

FIG. 5is a signal flow diagram of an exemplary embodiment for implementing an “always on” channel establishment procedure, whereby the terminal130of system150(shown inFIG. 2) is coupled with the UTRAN138and the access device142. Once the terminal130is enabled (step50), a 3G connection is established (step53), between the terminal130and the UTRAN138. The integrated access point/3G terminal130establishes the beacon channel (step52) to the access device142. The access device142realizes the integrated terminal130by standard IEEE 802.11 active or passive scanning methods (step51). Authentication (step54) of a user may be optionally implemented. The 3G radio bearer may be established either in conjunction with the 3G connection establishment procedure, (step53), or in conjunction with the association/re-association, (step55). Physical radio resources are either static assigned upon radio bearer establishment or dynamically allocated upon arrival of traffic data (IP packets), (step58). Traffic data is transmitted/received (step57) between the access device142and the UTRAN138, via the integrated terminal130.

FIG. 6is a signal flow diagram of an exemplary embodiment for implementing a sequence of events, whereby the terminal220of system200(shown inFIG. 3) is coupled with the UTRAN225and the access device205. Once the terminal220is enabled (step60), the 802.11 beacon channel is established. The access device205recognizes the integrated 802.11 access point/3G terminal220by standard IEEE 802.11 active or passive scanning methods (step61). When using passive scanning, the access device205receives a beacon transmission (step62) from the terminal220. Authentication (step63), of a user may be optionally implemented. Upon detection in the integrated terminal220of the 802.11 association or re-association procedure (step64), the integrated terminal220establishes a 3G connection and a radio bearer (step65), between the terminal220and the UTRAN225. Traffic data is transmitted/received (step66), between the access device205and UTRAN225via the terminal220. 3G physical radio resources are either dynamically allocated upon arrival of traffic data (IP packets) (step67), or statically assigned upon radio bearer establishment.

Although the integrated AP/3G terminals referred to herein may be considered to be an AP infrastructure topology for IEEE 802.11 networks, it is also possible to establish IEEE 802.11 “AdHoc” networks where no AP is involved. In this case, the access device or “station” may be similarly integrated with the 3G user terminal.

The foregoing describes a preferred example of an initialization scheme as per the invention. While this invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as described hereinabove.