HK1107485A - Limit redirections in an unlicensed mobile access network - Google Patents

Description

Restricting redirection in unlicensed mobile access networks

Technical Field

The present invention relates generally to the field of mobile communications, and more particularly, to a method and system for restricting redirection in an unlicensed mobile access network.

Background

In any mobile communication system, such as a global system for mobile communications (GSM) network, when a Mobile Station (MS) moves between different coverage areas or cells, it is necessary to hand over an active call conducted between the mobile station and a base station to a different base station. Depending on how each cell is defined, handover may require that the active call be rerouted only through a different Base Transceiver Station (BTS), through a different Base Station Controller (BSC), or through a different mobile services switching center (MSC). Handover may also be necessary when capacity problems are encountered in any cell.

Handover requires that a certain amount of operation and maintenance activities be performed at system installation, such as defining neighboring cells and the BSC and MSC controlling the cells, defining which cell frequencies should be measured and the thresholds used to initiate the handover. In a conventional GSM network, the BSC sends the MS a list of predetermined frequencies to be measured. Two lists may be sent out, a first list for idle mode, such as when the MS is roaming, and a second list for active mode when the call is in progress. This second list defines which frequencies the MS should measure and report back on. These lists contain a set of values relating to the Absolute Radio Frequency Channel Numbers (ARFCNs) of the neighbouring cells. In addition to these frequency channel numbers, the BSC also knows the Base Station Identity Codes (BSIC) of all neighboring cells. The MS measures the frequencies defined by these channel numbers and reports these measurements to the BSC. In practice, the MS will report only the six best measurements and only those cell frequencies at which the MS can synchronize and thus receive BSIC. The measurement report sent back by the MS to the BSC includes a reference to the ARFCN, the BSIC, and a received downlink signal strength indication. In fact, the report does not indicate the exact ARFCN, but rather the position this number occupies in the measurement list. The BSC decides whether handover is necessary and to which cell based on this report. The initiation of the handover is performed according to the standard GSM mechanism of each vendor. Specifically, a message indicating that a handover is required is sent by the base station controller to the MSC connected to the BSC. This message contains a cell identifier included in a Cell Global Identity (CGI) that defines the mobile country code, mobile network code, location area code and cell identifier of the cell to which handover is requested. The CGI is taken from the list by the BSC by using the BSIC and ARFCN of the obtained cell. With this CGI, the MSC is able to determine which other MSC handles the cell defined by the CGI value.

Recently it has been proposed to extend conventional cellular networks by including an access network that communicates with the MS using a low power unlicensed-radio interface. An Unlicensed Mobile Access (UMA) network (UMAN) is designed for use with the core elements of a standard public mobile network and consists essentially of a plug-in low-power unlicensed radio transceiver or Access Point (AP), each of which is designed to establish an unlicensed radio link with an MS, and a controller or interface node connecting the unlicensed radio transceiver and the mobile core network. Suitable unlicensed-radio formats include Digital Enhanced Cordless Telecommunications (DECT), Wireless Local Area Networks (WLAN) and bluetooth. A suitable mobile handset capable of operating over both a standard air interface (e.g., the Um interface) and an unlicensed-radio interface means that the user needs only one phone for all circumstances. The UMA network is constructed such that the core element of the MSC, such as the public mobile network, sees the interface node as a conventional BSC. Such ｃA umｃA network and an MS for such ｃA umｃA network are described in european patent application EP- ｃA-1207708. The contents of this application are incorporated herein by reference.

The low power and hence low range of the unlicensed-radio interface means that several such UMA networks may be provided in relatively close proximity, e.g. one access network per floor in an office building or private home. The connection between the unlicensed-radio transceiver and the associated unlicensed-network controller (UNC) is provided over a fixed broadband network. Preferably, the communication over this network uses the Internet Protocol (IP), which greatly facilitates the installation of UMA networks, allowing users to plug in unlicensed-radio transceivers in their own homes, and thus install unlicensed-radio Access Points (APs) themselves. However, the flexibility of such UMA networks also presents difficulties. Since the access points can be freely installed and moved by the user to different cities, states or even countries, but still connected to their original UNC, the core network cannot track the exact location of the APs. This puts high demands on the operation and maintenance activities required for handover to and from the UMA network, since the neighbouring cells will change frequently. Furthermore, billing constraints for some areas may require reassignment of relocated APs to more appropriate UNCs, especially when call revenues originating from a particular AP must be calculated in a particular region of a country. Therefore, their configuration and relocation when the MS moves in and out of the AP and UMA network presents a significant challenge to the service expansion of the UMA network.

Furthermore, a redirection or re-assignment function is required to connect the MS to the correct UNC via the AP. This facilitates the possibility of performing a handover to a licensed mobile spectrum. Since the redirection function in UNC relies on data assigned by a person (or other machine), the data may be corrupted. Thus, the system is susceptible to infinite redirection.

Disclosure of Invention

The present invention provides a method and system for restricting redirections using a redirection counter contained within an MS registration request. Once the redirection counter exceeds a certain redirection value for the MS, the UNC will reject any registration request for the MS. The UNC may also record the case where the redirection counter has exceeded a certain value. The registration request suspension system improves efficiency, reduces network load, avoids the system from unlimited registration requests, and can help to locate faults.

More specifically, the present invention provides a method for limiting redirection of a mobile station in an unlicensed radio access network by initializing a redirection counter, including the redirection counter in a registration request, and incrementing the redirection counter each time a redirection response is received in response to the registration request. The redirection counter is typically initialized to zero at the first registration request. Additional steps may include creating the registration request, sending the registration request to an unlicensed mobile access network controller, or receiving a response to the registration request.

In addition, the present invention provides a method of restricting redirection of a mobile station in an unlicensed radio access network by receiving a registration request including a redirection counter, processing the registration request normally as long as the redirection counter does not exceed a certain value, and sending a reject response as long as the redirection counter exceeds a certain value. The method may further comprise the step of creating a log or creating a rejection response whenever the redirection counter exceeds the value. The above-described methods may be implemented using a computer program embodied on a computer readable medium, wherein each step is performed by one or more code segments.

The present invention also provides an electronic communication including a registration request and a redirection counter. The electronic communication is typically sent from the mobile station to an unlicensed mobile access network controller in the unlicensed radio access network.

In addition, the present invention provides an apparatus for limiting redirection of one or more mobile stations within an unlicensed radio access network by using a redirection counter to determine whether to deny a registration request. Similarly, the present invention provides an unlicensed-radio access system connected to the core network portion of a licensed mobile network, the unlicensed-radio access system including one or more access points adapted to communicate with mobile stations over an unlicensed-radio interface, one or more unlicensed mobile access point controllers connected to the core network portion of the licensed mobile network, and a fixed broadband network connected to the access points and the unlicensed mobile access point controllers, wherein the one or more unlicensed mobile access point controllers limit the redirection of mobile stations using a redirection counter in each registration request by a mobile station.

Drawings

Further advantages and advantages of the invention will become more apparent from the following description of various embodiments, given by way of example, with reference to the accompanying drawings, in which:

fig. 1 is a block diagram illustrating portions of a GSM network having a UMA network in accordance with the present invention;

FIG. 2 is a block diagram of a UMA high level functional architecture;

fig. 3 is a block diagram illustrating the logical roles of a UNC in accordance with the present invention;

fig. 4 is a flow diagram illustrating a basic method for assigning an MS to a UNC according to one embodiment of the present invention;

fig. 5 is a flow chart illustrating a more detailed method for assigning an MS to a UNC in accordance with the present invention;

FIGS. 6A and 6B illustrate representative signaling sequences in accordance with the present invention;

fig. 7 is a flowchart illustrating a registration procedure of UNC entries stored in an MS according to one embodiment of the present invention;

fig. 8, 9 and 10 are flowcharts illustrating an UNC discovery/registration procedure for an MS according to one embodiment of the present invention;

FIG. 11 is a flow diagram illustrating a reject and no response process according to one embodiment of the invention;

FIG. 12 is a flow chart illustrating a redirect counter system on an MS in accordance with the present invention; and

fig. 13 is a flow chart illustrating the reduction of registration requests in accordance with the present invention.

Detailed Description

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.

To facilitate an understanding of the present invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by one of ordinary skill in the art to which the invention pertains. Terms such as "a," "an," and "the" are not meant to refer to only a singular entity, but include the general class of which a particular example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but its use is not limiting of the invention, except to those outlined in the claims.

The present invention provides a method and system for restricting redirections using a redirection counter contained within an MS registration request. Once the redirection counter exceeds the maximum redirection value for the MS, the UNC will reject any registration request for the MS. The UNC may also record the case where the redirection counter has exceeded a certain value. The registration request suspension system improves efficiency, reduces network load, avoids the system from unlimited registration requests, and can help to locate faults.

Referring now to fig. 1, a block diagram illustrating portions of a GSM network 100 having a UMA network 102 in accordance with the present invention is shown. The GSM network 100 is essentially divided into a core network portion 104 and an access portion 106. The components of the core network 104 include Mobile Switching Centers (MSCs) 108 and 110, an associated Home Location Register (HLR)112, and Visitor Location Registers (VLRs) 114 and 116. The function and structure of these conventional GSM architecture components are known to those skilled in the art and will not be described in further detail herein. The core network 104 also supports General Packet Radio Service (GPRS) and for this purpose illustrates Serving GPRS Support Nodes (SGSN)118 and 120. Although not shown in the figures, those skilled in the art will appreciate that the core network 104 may include access to other mobile and fixed line networks (e.g., ISDN and PSTN networks), packet and circuit switched packet data networks (e.g., intranets, extranets and the internet) through one or more gateway nodes.

The access portion 106 is essentially comprised of a plurality of Base Station Subsystems (BSSs) 122, only one of which is shown in the figure. The BSS122 includes one or more Base Station Controllers (BSCs) 124 and one or more Base Transceiver Stations (BTSs) 126, 128, and 130. The BSS122 or BSC124 communicates with the MSC110 and SGSN120 in the core network portion 104 via defined fixed standard a and Gb interfaces, respectively. The BSC124 communicates with one or more BTSs 126, 128, and 130 via a defined Abis air interface. The BTS130 communicates with mobile stations or terminals (MS or MT132) over the GSM standard Um radio air interface. Note that the BSC124 is often separate from the BTSs 126, 128, and 130, and may even be located at the MSC 110. The physical division shown in figure 1 serves to distinguish between the network parts making up the access network portion 106 and the network parts forming the core network portion 104.

In addition to the standard access network portion provided by BSS122, the network shown in fig. 1 also includes an unlicensed radio access network (UMAN 102). The components making up the UMAN102 also enable the MS132 to access the GSM core network 104 and thus other communication networks via the unlicensed-radio interface X. Unlicensed-radio, as used herein, refers to any radio protocol that does not require that the operator running the mobile network has obtained a license from the corresponding regulatory body. Typically, such unlicensed-radio technologies must be low power and therefore have a limited range compared to licensed mobile radio services. This means that the battery life of the mobile terminal will be longer. Also, because of the small range, the unlicensed-radio may be a broadband radio, thereby providing improved voice quality. The radio interface may utilize any suitable unlicensed-radio protocol, such as the wireless LAN protocol, bluetooth radio, or enhanced digital radio telecommunications (DECT). These radios have higher bandwidth and lower power consumption than conventional public mobile network radios.

The bluetooth standard specifies a two-way digital radio link for short-range connections between different devices. The device is equipped with a transceiver that transmits and receives in a frequency band of about 2.45 GHz. The band is available globally and varies according to the different bandwidths of the country. Data and voice channels may be provided. Each device has a unique 48-bit address from the IEEE802 standard. Built-in encryption and authentication may also be provided.

The components of the UMAN102 that are adapted to communicate across the unlicensed-radio interface are referred to as Access Points (APs) 134, 136, 138 and 140 (also referred to as local or Home Base Stations (HBSs)). The AP134 handles the radio link protocol with the MS132 and contains radio transceivers that define cells in a manner similar to the operation of a conventional GSM BTS 130. An Unlicensed Network Controller (UNC)142, 144, or 146 (also known as a Home Base Station Controller (HBSC)) controls the AP134 and communicates with the MSC110 over a GSM standard a interface and also communicates with the serving GPRS support node SGSN120 over a standard Gb interface, if available in the core network 104. The combined functionality of the AP134 and UNC142 mimics the operation of the BSS122 with the SGSN120 and MSC 110. In other words, the UMAN102, comprised of the APs 134, 136, 138 and 140 and the UNC142, appears as a conventional access network 106 when viewed from the components of the core network 104, e.g., the MSC110 and the Serving GPRS Support Node (SGSN) 120.

The interface between the access points 134 etc and the UNC142 is preferably provided by a fixed link. A home base station (not shown, but which may be integrated in an AP) is often a small device that a user can purchase and install in a desired location (e.g., a home or office environment) to enable fixed access to the UMA network. However, operators may also install them in service hotspots. To reduce installation costs on the part of the operator, the interface between the home base station (not shown) and the UNC142 preferably utilizes an already existing connection provided by the fixed network 148. Preferably, the network 148 is a broadband packet-switched network. Suitable networks may include those based on ADSL, ethernet, LMDS or the like. Home connections to such networks are increasingly available to users.

Referring now to FIG. 2, a block diagram of a UMA high-level functional architecture is shown. The UMAN102 includes one or more APs 134 and one or more UNCs 142 (each having a security gateway 150(UNC SGW)) interconnected by a broadband IP network 148. The UNC SGW150 terminates the secure remote access tunnel from the MS132 and provides mutual authentication, ciphering, and data integrity for signaling, voice, and data traffic. Note that each UNC142 may have multiple UNCSGWs, or a UNC SGW pool may serve multiple UNCs. The UMAN102 co-exists with the GSM/GPRS radio access network and interconnects with the GSM core network 104 via the same interfaces used by the following standard GERAN BSS network elements: a GSM a interface for circuit switched services; a GPRS Gb interface for packet services; and a Wm interface for authentication, authorization, and accounting. The UNC142 appears to the GSM/GPRS core network 104 to be a GERAN BSS. The main components of transaction control (e.g., call processing) and user services are provided by network elements in the core network 104, i.e., by the MSC110, SGSN/GGSN120, authentication, authorization and accounting proxy/server 152(AAA proxy/server), and VLR/HLR 116. The AAA proxy/server 152 is connected to the VLR/HLR116 via a D '/Gr' interface. The GSM/GPRS core network 104 interfaces with the MS's home public land mobile network 154(HPLMN) whenever the MS132 is roaming. Specifically, the AAA proxy/server 152 will connect with the AAA server 156 via the Wd interface. The AAA server 156 will be connected to the HLR158 via the D '/Gr' interface.

The broadband IP network 148 provides a connection between the subscriber's home and the UNC 142. The AP134 in the subscriber's home provides a radio link to the MS132 using unlicensed spectrum. The IP transport network extends all the way from the UNC142 to the MS132 through the AP 134. A single interface Ut is defined between the UNC142 and the MS 132. The Mt interface is the interface between the UNC142 and the AP 134. In some implementations the interface may be used for a dedicated function. The Ut and Mt interfaces are collectively referred to as the Up interface.

The MS132 provides dual mode (licensed and unlicensed) radios and the ability to switch between them. MS132 supports an IP interface to AP 134. In other words, the IP network extends from the UNC142 all the way to the MS 132. The MS132 is defined for bluetooth (using the bluetooth PAN application specification) and for 802.11. The AP134 provides a radio link to the MS132 using unlicensed spectrum and is connected to the UNC142 over a broadband IP network 148. The AP134 provides bluetooth (PAN application profile) or 802.11 access point functionality. The AP134 may also use other radio access technologies such as 802.16 or 802.20, etc. Any "standard" AP may be used to interconnect the MS132 with the broadband IP network 148.

The UNC142 is connected to the unique MSC110 and SGSN120 via an a interface and a Gb interface, respectively. This does not exclude support for the A-flex and Gb-flex properties. The UNC142 provides functionality equivalent to that of a GSM/GPRS BSC. The UNC142 is connected to the AP134 via the IP transport network 148. The UNC142 connects with the MS132 using the Ut interface and maintains end-to-end communication with the MS132 and relays GSM/GPRS signaling to the a/Gb interface to the core network 104. The UNC142 performs the following functions: transcoding voice from MSC110 to MS 132/from MS132 to MSC110 to PCM voice when TFO/TrFO features are not utilized; and the following Ut functionality: registration for UMA service access; establishment of UMA bearer paths for CS and PS traffic, including participation in the establishment, management and teardown of secure signaling and user plane bearers between the MS132 and the UNC 142; UMA equivalent functionality for paging and handover; and transparent transfer of L3 messages between the MS132 and the core network 104.

Referring now to fig. 3, there is shown a block diagram illustrating the logical role of the UNC142 in accordance with the present invention. As described above, the present invention provides a UNC142 that can perform one, two, or all three logical functions (e.g., assignments 300, defaults 302, and services 304). This logical division of roles in the UMA network improves network performance, improves reliability, and provides improved load balancing. Accordingly, the present invention provides various procedures performed by the MS and UNCs different from each other. Furthermore, the present invention provides a method for the MS to contact the assigned UNC to find the default UNC that will be used to find the correct serving UNC.

Referring now to fig. 4, a flow diagram is shown illustrating a basic method 400 for assigning an MS to a UNC in accordance with one embodiment of the present invention. When a UMA-capable MS first attempts to connect to a UNC based on a UMA subscription, it needs to identify the default UNC. To do this, it first connects to the assigning UNC, then discovers the default UNC, which can then redirect the MS to the serving UNC. More specifically, the MS connects to the assigning UNC in block 402 and discovers the default UNC in block 404. This operation is only done once as long as a default UNC is available. After discovering the default UNC, the MS disconnects from the assigning UNC, connects to the default UNC, and registers with the default UNC in block 404. The serving UNC to which the MS is assigned is then determined in block 406 and the MS is assigned (registered) to the serving UNC in block 408. The serving UNC may be a default UNC, an assigned UNC, or another UNC. If the serving UNC is the default UNC, the registration step in block 408 has been performed in block 404. If, however, the serving UNC is not the default UNC, the MS is redirected to the serving UNC and disconnected from the default UNC, connected to the serving UNC, and registered with the serving UNC in block 408.

Referring now to fig. 5, a flow diagram is shown illustrating a more detailed method 500 for assigning an MS to a UNC in accordance with the present invention. In block 502, the MS first joins the AP. If the MS has UNC data stored, as determined in decision block 504, then in block 506, a registration process for the stored UNC entry is performed. This process is further described below with reference to fig. 7. If the registration is accepted as determined in decision block 508, then in block 510, the service is established. If, however, the MS does not have UNC data stored corresponding to the joined AP, as determined in decision block 506, then in block 512, a discovery/registration process for the UNC is performed. This process is further described below with reference to fig. 8. If registration is accepted as determined in decision block 514, then in block 510, the service is established. If, however, the registration is not accepted as determined in decision block 514, then one or more rejection rules are executed in block 516. This process is further described below with reference to fig. 11.

Referring now to fig. 6A and 6B, representative signaling sequences in accordance with the present invention are illustrated. The following description assumes that the MS has joined an AP providing unlicensed radio access. What signal levels should be considered sufficient to trigger UMAN discovery and registration procedures depends on the implementation. When attempting to acquire UMA services for the first time, a discovery procedure is performed by the MS to determine the identity of the serving UNC which may also be the default UNC for the connection.

A UMA-capable MS may be assigned (e.g., on a SIM) a Fully Qualified Domain Name (FQDN) or IP address that assigns a UNC and an associated Security Gateway (SGW). If the SIM is not assigned an FQDN or IP address, the MS will derive the FQDN assigned the UNC and the security gateway based on its IMSI. For example, the FQDN may conform to the following format:

assigned UNC-SGW: ygw.uma.mncnnn.mccmmm.uma.3gppnetwork.org

Assigned UNC: micron, mcnnn, mccmmm, uma, 3gppnetwork, org

Wherein "nnn" and "mmm" are replaced by IMSI MCC and MNC information in the SIM.

The MS will establish a secure tunnel using the assigned or derived address and connect to the assigned UNC. It will then acquire the FQDN or IP address of the default UNC and associated SGW through the discovery process. When the MS fails to register on the alternative serving UNC, the default UNC serves as the primary registration destination address for the MS. These alternative serving UNC addresses are stored in the MS at the GSM CGI level when the MS is in GSM coverage or at the AP level when there is no GSM coverage. After the discovery process, the MS will establish a secure tunnel with a security gateway of the default UNC and attempt to register with the default UNC. The default UNC network may also serve as the serving UNC for the connection. This procedure may result in the MS being redirected to a different serving UNC.

UNC redirection refers to the ability of a UNC to redirect an MS to a different UNC than the UNC it originally requested access to based on information provided by the MS and operator-selected policies. For example, a "suitable" serving UNC is one whose UMA service areas "overlap" the umbrella GSM coverage of the MS. The correct serving UNC can be attached to the same MSC as the GSM BSC to which the umbrella GSM cell belongs. The correct serving UNC can be attached to a different MSC that can switch to the MSC that provides umbrella GSM coverage to the MS.

If no GSM coverage is available when an MS connects to a UNC to obtain UMA service, the UNC cannot reliably determine the location of the MS for the purpose of assigning the MS to the correct serving UNC (to enable handover and location-based services). The UNC will allow the operator to determine the service policy in this case; for example, the operator may offer services to the user with some restrictions (perhaps with a user interface indication on the MS).

The MS is connected to the assigning UNC by joining the MS to the UMAN via an Access Point (AP) and connecting the MS to the assigning UNC via the AP. Each UNC is assigned one or more logical roles selected from assignment, default, or service. Furthermore, the present invention provides a method for assigning an MS to a UNC in a UMAN by: the MS joins the UMAN via the AP and attempts a discovery/registration procedure for one or more UNCs and assigns the MS to one of the UNCs as long as the discovery/registration procedure is successful. The process also attempts a registration process for one or more previously connected UNCs whose locations are stored on the MS and assigns the MS to the previously connected UNC whenever the registration process is successful. One or more rejection procedures may be performed as long as the discovery/registration process is unsuccessful. The methods described above may be implemented using a computer program embodied on a computer readable medium, wherein each step is performed by one or more code segments.

Furthermore, the present invention provides an apparatus within a UMA network that facilitates the assignment of one or more MSs within the UMA network. The apparatus includes a UNC assigned one or more logical roles selected from assignment, default, or service. The logical roles, i.e., assignment, default, and service, are distributed across one or more UNCs.

The UNC is an assigned UNC with respect to the first set of MSs; a default UNC with respect to a second set of MSs; and a serving UNC with respect to the third set of MSs. Furthermore, the present invention provides an unlicensed-radio access system connected to a core network portion of a licensed mobile network. The unlicensed-radio access system includes one or more APs adapted to communicate with the MS over an unlicensed-radio interface, one or more UNCs connected to a core network portion of the licensed mobile network, and a fixed broadband network connected to both the APs and the UNCs, wherein the UNCs provide logical roles of provisioning, defaulting, and serving to facilitate designation of the MS within the UMA network.

651: if the MS600 has an assigned or derived FQDN that assigns the SGW606, it performs a DNS query 651 (via the AP providing unlicensed radio access) to resolve the FQDN to an IP address. If the MS600 has an assigned IP address that assigns the SGW606, DNS steps 651 and 652 will be omitted.

652: DNS server 602 returns a response.

653: the MS600 establishes a secure tunnel to the assigned SGW 606.

654: if the MS600 has an assigned or derived FQDN that assigns UNC608, it performs a DNS query 654 (via a secure tunnel) to resolve the FQDN to an IP address. If the MS600 has an assigned IP address that assigns UNC608, the DNS step will be omitted.

655: DNS server 610 returns response 655.

656: the MS600 establishes a TCP session to a well-defined port of the assigned UNC 608.

657: the MS600 queries the provisioning UNC608 using a URR discovery request 657 to obtain the default UNC 615. The message comprises:

GSM cell information;

the currently camped (camping) GSM CGI or the last CGI to successfully register the MS, along with an indicator to indicate which one it is;

an AP identity;

the broadcast air interface MAC address of the AP that the MS is using;

-an MS identity;

-IMSI。

658: the assignment UNC608 returns a URR discovery accept message 658 using location information (e.g., CGI) provided by the MS600 to provide the FQDN or IP address of the default UNC615 and its associated default SGW 614. The message may also contain the TCP port number used for the default UNC 615. Furthermore, this is done so that the MS600 is directed to a "local" default UNC to optimize network operation.

659: alternatively, the assignment UNC608 may return a URR discovery rejection 659 indicating the reason for the rejection. Rejection may be triggered for a number of reasons, including:

network congestion: in this case, the request cannot be serviced immediately. The MS600 should wait a random time before initiating the second attempt. The MS600 should double the latency for each successive failed attempt. After 5 failed attempts, the MS600 should restart the discovery process.

Position is not allowed: the MS600 is attempting to connect to an operator that has no roaming agreement with the MS 600's home operator. The MS600 will no longer attempt the discovery process from this prohibited location (i.e., the country, PLMN, or location indicated in the URR discovery reject message 659). When the MS600 is no longer in the prohibited location, the MS600 may retry the discovery process using the stored assignment UNC608 (e.g., in the SIM).

UMA services are not allowed: the operator policy determines that no UMA service is available. The MS600 will not reattempt discovery on the UMA network. This condition will remain until the MS is powered off.

IMSI is not allowed: the operator policy determines that IMSI is not allowed. The MS600 will not reattempt discovery on the UMA network. This condition will remain until the MS is powered off.

Not specified: no reason is returned. The MS600 will not reattempt discovery on the UMA network. This condition will remain until the MS is powered off.

The AP is not allowed: operator policy determines that no UMA service is available on this AP. The MS600 may retry the discovery process from another AP.

If the MS600 fails to receive any response from the provisioning UNC608, the MS600 will behave as if it received a URR discovery rejection 659 with the cause of network congestion attached.

660: the first TCP connection 656 is then released 660.

661: if the assigning UNC608 and default UNC616 support the same SGW (in this case the assigning SGW606), the same secure tunnel 653 can be used. Otherwise, the first secure tunnel 653 is released 660 and a new secure tunnel is established 662.

662: if the MS600 is provided with only the FQDN of the default SGW614, the MS600 will first resolve the IP address (via the WLAN interface) via a DNS query. The MS600 will then establish a secure tunnel 662 to the default SGW 614. If the MS600 is provided with only the FQDN of the default UNC616, the MS600 will then resolve the IP address (via the secure tunnel 662) through a DNS query.

663: the MS600 then establishes a TCP session 663 to the well-defined port on the default UNC616 or the port returned in the URR discovery accept 658.

664: the MS600 will attempt to register on the default UNC616 by sending a URR registration request 664. The message comprises:

GSM cell information;

the GSM CGI currently camped on or the last CGI that successfully registered the MS600, along with an indicator to indicate which one it is;

an AP identity;

the broadcast air interface MAC address of the AP that MS600 is using;

an MS identity;

IMSI。

665: if the default UNC616 wishes to redirect the MS600 to another serving UNC624, it will respond with a URR registration redirect 665, which provides the FQDN or IP address of the target serving UNC624 and associated SGW 622. Alternatively, the default UNC616 may deny registration, and in this case the default UNC616 will respond with a URR registration denial (not shown) indicating the reason for the denial. This may be triggered for a number of reasons, for example:

redirection due to load balancing: a particular UNC is overloaded and the MS600 is redirected to another UNC.

Network congestion: the MS600 cannot be served immediately. The MS600 will wait a random time before initiating the second attempt. The MS600 doubles the latency for each successive failed attempt. After 5 failed attempts, the MS600 will restart the registration process.

Restart discovery at the assignment UNC 608: the MS600 will restart the discovery process by contacting the stored assigned UNC604 (e.g., in the SIM).

Position is not allowed: the MS600 will not attempt to register with the UNC. The MS600 may retry the discovery process using the stored assignment UNC608 (e.g., in the SIM).

UMA services are not allowed: the operator policy determines that no UMA service is available. The MS600 will not reattempt registration on the UMA network. This condition will remain until MS600 is powered off.

The AP is not allowed: operator policy determines that no UMA service is available on this AP. MS600 may retry the registration procedure from another AP.

Alternatively, the default UNC616 may return a URR registration accept 664 to accept the registration per step 668.

666: the second TCP connection 663 is then released 666.

667: if the default UNC616 and serving UNC624 support the same SGW (in this case, the assigned SGW614), the same secure tunnel 662 may be used. Otherwise, the first secure tunnel 662 is released 667 and a new secure tunnel is established 668.

668: if the MS600 is redirected and only the FQDN serving the SGW622 is provided to the MS600, the MS600 will first resolve the IP address (via the WLAN interface) via a DNS query. MS600 will then establish a secure tunnel to serving SGW 622. If the MS600 is provided with only the FQDN serving the UNC624, the MS600 will then resolve the IP address (via the secure tunnel) through a DNS query. The MS600 then establishes a TCP session to a well-defined port on the serving UNC 624.

669: the MS600 will attempt to register on the serving UNC624 by sending a URR registration request 669. The message comprises:

GSM cell information: the GSM CGI currently camped on or the last CGI that successfully registered the MS600, along with an indicator to indicate which one it is.

AP identity: the broadcast air interface MAC address of the AP being used by MS 600.

MS identity: an IMSI.

670: if serving UNC624 accepts the registration attempt, it will respond with URR registration accept 670. The message comprises:

cell descriptions including BCCH ARFCN, PLMN color codes and base station color codes;

including a mobile country code, a mobile network code, and a location area identification of the location area code corresponding to the UNC cell.

Cell identities of cells within the location area are identified.

671: alternatively, the serving UNC624 may deny the request or redirect the MS600 to another serving UNC 624.

Referring now to fig. 7, a flow diagram is shown illustrating a registration process 506 for UNC entries stored in an MS in accordance with one embodiment of the present invention. The MS will store (e.g., on the SIM) the addresses of the assigned UNC and the default UNC (along with the associated SGW). The MS will also store the following information on each UNC that the MS was previously able to complete a successful registration procedure at the GSM CGI level when the MS is in GSM coverage or at the AP level (e.g., on the SIM) when there is no GSM coverage. These alternative serving UNC addresses are stored in the MS.

Cell Global Identity (CGI) of GSM cell where MS was located before registration;

a service SGW identity address received after successful registration;

the service UNC IP address received after successful registration.

The number of such items to be stored in the MS may be one or several. For a particular AP, only the UNC associations that were last successfully registered will be stored. The MS may preferentially join a WLAN AP whose association with the serving UNC is already stored in memory.

Upon joining the WLAN, if the MS is in GSM coverage as determined in decision block 700 and the MS stores serving UNC information for the current GSM CGI as determined in decision block 702, the MS will attempt to register with the serving UNC by establishing a secure tunnel to the serving SGW in block 706. However, if the MS is not in GSM coverage as determined in decision block 700 and the MS stores serving UNC information for the current AP ID as determined in decision block 704, the MS will attempt to register with the serving UNC by establishing a secure tunnel to the serving SGW in block 706.

After establishing the secure tunnel in block 706, the MS establishes a TCP session to a port on the serving UNC in block 708 and requests registration on the serving UNC in block 710. If the UNC accepts the MS, registration is completed and service is established in block 712. If the UNC redirects the MS to another UNC, in block 706, a secure tunnel is established and the process as described herein is repeated. The UNC may reject the MS for any reason even though it may have previously served the MS. In such a case, the MS will delete the address of the serving UNC from its stored list upon receiving the registration rejection in block 714.

If the MS does not receive a response to the registration request to the serving UNC, the entry is deleted in block 714. Thereafter, or if the MS has not stored serving UNC information for the current GSM CGI, as determined in decision block 702, or the MS has not stored serving UNC information for the current AP ID, as determined in decision block 704, the MS will check whether there is a stored entry for the default UNC, as determined in decision block 716. If the MS does not have a store of default UNCs, it will attempt the discovery/registration process with the assigned UNC to acquire a new default UNC in block 718. This process is described in more detail below with reference to fig. 8.

However, if the MS does not have a stored entry for the default UNC, as determined in decision block 716, the MS will attempt to register with the default UNC to acquire a new serving UNC for the joined AP by establishing a secure tunnel to the default SGW in block 720, establishing a TCP session to a port on the default UNC in block 722, and requesting registration on the default UNC in block 724. If the request is accepted, registration is completed and the service is established in block 712. If the UNC redirects the MS to another UNC, in block 706, a secure tunnel is established and the process as described herein is repeated. If the request is denied or the MS does not receive a response to the registration request to the default UNC for a period of time, the default UNC is deleted from the stored list in block 726. In block 718, the MS will then attempt the discovery/registration process with the assigned UNC to acquire a new default UNC. This process is described in more detail below with reference to fig. 8.

Referring now to fig. 8, 9 and 10, flow diagrams illustrating UNC discovery/registration processes 512 (fig. 5) and 718 (fig. 7) of an MS according to one embodiment of the present invention are shown. When the MS joins the WLAN for which the MS does not have a stored serving UNC in its memory, it will attempt to register with the default UNC. The discovery and registration process consists of the following steps:

and (3) joining the WLAN:

discovering a default UNC by assigning the UNC;

registering to a default UNC;

possibly redirected to the serving UNC or rejected;

registered with the serving UNC.

Through the registration procedure, the MS may be redirected to another serving UNC. This may be based on the following reasons, among others:

a current location indicated by an overlapping GERAN cell global identity or other location attribute;

an indication of a joined AP;

load balancing in the NW;

operator policy;

roaming agreement in case of roaming MS.

A successful registration procedure results in the UNC establishing the context of the MS. The MS acquires the necessary system information for the UMAN on which it has registered and may trigger a normal location/routing area update procedure with the CN.

More specifically, if the MS has an assigned or derived FQDN that assigns an SGW at 800, the MS will perform a DNS query to resolve the FQDN that assigns the SGW to an IP address in block 802. Thereafter, or if at 804 the MS has an assigned IP address of the assigned SGW, a secure tunnel is established to the assigned SGW in block 806. Thereafter, if the MS has an assigned or derived FQDN that assigns a UNC at 808, the MS will perform a DNS query to resolve the FQDN of the assigned UNC to an IP address in block 810. Thereafter, or if at 812 the MS has an assigned IP address for the assigned UNC, a TCP connection to the assigned UNC is established in block 814 and the assigned UNC is queried for the default UNC in block 816. If there is no response, then in block 810, a no response procedure is performed. If the query is rejected, in block 820, a rejection procedure is performed. The no response procedure 810 and the rejection procedure 820 are described in more detail below with reference to fig. 11.

If the query is accepted and the IP address of the default UNC is received based on the MS location information 822, a secure tunnel is established to the default SGW in block 826. On the other hand, if the query is accepted 824 and the FQDN of the default UNC and associated default SGW are received based on the MS location information, then in block 828, a DNS query is performed to resolve the FQDN of the default SGW to an IP address, and in block 830, a secure tunnel is established to the default SGW. If the MS has the FQDN of the default UNC at 832, a DNS query is performed to resolve the FQDN of the default UNC to an IP address at 834. Thereafter, or if the MS has the IP address of the default UNC at 836, or a secure tunnel has been established at block 826, a TCP session is established to a port on the default UNC at block 838. The MS then requests registration with the default UNC in block 840.

If the request is accepted, registration is completed and service is established in block 842. If there is no response, in block 844, a no response procedure is performed. If the request is denied, in block 846, a denial process is performed. The no response procedure 844 and the reject procedure 846 are described in more detail below with reference to fig. 11. If a redirect is received along with the IP address of the serving UNC and associated serving SGW at 848, a secure tunnel is established to the serving SGW in block 852. On the other hand, if a redirection is received at 850 along with the FQDN of the serving UNC and associated serving SGW, then at block 854 a DNS query is performed to resolve the FQDN of the serving SGW to an IP address and at block 856 a secure tunnel is established to the serving SGW. If the MS has the FQDN of the serving UNC at 858, then at block 860 a DNS query is performed to resolve the FQDN of the serving UNC to an IP address. Thereafter, or if the MS has the IP address of the serving UNC at 862 or a secure tunnel is established at 852, a TCP session is established to a port on the serving UNC at 864. The MS then requests registration with the serving UNC in block 866.

If the request is accepted, registration is completed and service is established in block 868. If there is no response, in block 870, a no response procedure is performed. If the request is denied, in block 872, a denial process is performed. The no response procedure 870 and the rejection procedure 872 are described in more detail below with reference to fig. 11. If a redirect is received, the process repeats at 874 to 848 and 876 to 850.

Referring now to fig. 11, a flow diagram is shown illustrating the rejection processes 516 (fig. 5), 820 (fig. 8), 846 (fig. 9), and 872 (fig. 10) and the no response processes 818 (fig. 8), 844 (fig. 9), and 870 (fig. 10) according to one embodiment of the invention. If the rejection is network congestion or no response and no previous attempts have failed as determined in decision block 900, the MS will not initiate the next discovery or registration attempt until after waiting in block 902. If, however, the previous attempt failed as determined in decision block 900, and there have been less than 5 failed attempts as determined in decision block 904, then the wait time is doubled in block 906, and the MS will not initiate the next discovery or registration attempt until after waiting in block 902. If, however, there have been 5 failed attempts, as determined in decision block 904, then in block 908, the discovery or registration process is restarted.

If the rejection is location not allowed, then the MS will not attempt discovery or registration from the barred location (i.e., the country, PLMN, or location indicated in the URR discovery reject message) in block 910, and the MS may retry the discovery or registration process with the stored assignment UNC when the MS is no longer in the barred location in block 912. If the rejection is that the AP is not allowed, then in block 914, no service is available on the joining AP and in block 916 the MS may retry the discovery or registration procedure on another AP. If the rejection is a redirection due to load balancing, the MS is redirected to another UNC in block 918. If the rejection is to restart discovery at the assigning UNC, the MS restarts the discovery process by contacting the stored assigning UNC in block 920. If rejection is UMA service not allowed or IMSI not allowed or rejection is unspecified, then in block 922, no service is available and re-attempt registration is not allowed.

Referring now to fig. 12, there is shown a flow chart 1200 illustrating a redirection counter system on MS1202 in accordance with the present invention. If this is the first registration attempt of the MS1202, as determined in decision block 1204, the redirection counter is set to zero in block 1206. Thereafter, and if this is not the first registration attempt of the MS1202, as determined in decision block 1204, a registration request containing a redirection counter is sent to the appropriate UNC. If the MS1202 receives a redirect response, as determined in decision block 1210, the redirect counter is incremented in block 1212. Thereafter, or if a redirect response is not received, the process returns to decision block 1204 to send out the next registration request.

In another embodiment, the present invention provides a method of restricting redirection of a mobile station in an unlicensed radio access network by initializing a redirection counter, including the redirection counter in a registration request, and incrementing the redirection counter each time a redirection response is received in response to the registration request. The redirection counter is typically initialized to zero at the first registration request. Additional steps may include creating the registration request, sending the registration request to an unlicensed mobile access network controller, or receiving a response to the registration request.

Referring now to fig. 13, a flow diagram is shown illustrating the reduction of the number of redirections originating from UNC1302 in accordance with the present invention. UNC1302 receives a registration request containing a redirection counter in block 1304. If the redirect counter does not exceed a certain value, as determined in decision block 1306, normal processing continues in block 1308. If, however, the redirect counter exceeds the value, as determined in decision block 1306, the registration request is denied in block 1310 and an event is recorded 1312.

Similarly, the present invention provides a method of restricting redirection of a mobile station in an unlicensed radio access network by receiving a registration request including a redirection counter, processing the registration request normally as long as the redirection counter does not exceed a certain value, and sending a reject response as long as the redirection counter exceeds a certain value. The method may further comprise the step of creating a log or creating a rejection response whenever the redirection counter exceeds the value. The above-described methods may be implemented using a computer program embodied on a computer readable medium, wherein each step is performed by one or more code segments.

The present invention also provides an electronic communication including a registration request and a redirection counter. The electronic communication is typically sent from the mobile station to an unlicensed mobile access network controller in the unlicensed radio access network.

In addition, the present invention provides an apparatus for limiting redirection of one or more mobile stations within an unlicensed radio access network by using a redirection counter to determine whether to deny a registration request. Similarly, the present invention provides an unlicensed-radio access system connected to the core network portion of a licensed mobile network, the unlicensed-radio access system including one or more access points adapted to communicate with mobile stations over an unlicensed-radio interface, one or more unlicensed mobile access point controllers connected to the core network portion of the licensed mobile network, and a fixed broadband network connected to the access points and the unlicensed mobile access point controllers, wherein the one or more unlicensed mobile access point controllers limit the redirection of mobile stations using a redirection counter in each registration request by a mobile station.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification, but only by the claims.

Claims (20)

1. A method of restricting redirection of a mobile station (132) in an unlicensed-radio access network (102), said method comprising the steps of:

initializing a redirect counter (1206);

including the redirection counter in a registration request (1208); and

the redirect counter is incremented each time a redirect response is received in response to the registration request (1212).

2. The method of claim 1, wherein the redirection counter is initialized to zero (1206) at a first registration request (1204).

3. The method of claim 1, further comprising the step of creating the registration request.

4. The method of claim 1, further comprising the step of sending (1208) the registration request to an unlicensed mobile access network controller (142).

5. The method of claim 1, further comprising the step of receiving a response (1210) to the registration request.

6. A method of restricting redirection of a mobile station (132) in an unlicensed-radio access network (102), said method comprising the steps of:

receiving a registration request (1304) including a redirection counter;

processing the registration request normally as long as the redirection counter does not exceed a certain value (1308); and

a rejection response is sent whenever the redirection counter exceeds the value (1310).

7. The method of claim 6, further comprising the step of creating a log (1312) whenever the redirect counter exceeds the value.

8. The method of claim 6, further comprising the step of creating the reject response.

9. An electronic communication, comprising:

a registration request (663 or 667); and

a redirection counter.

10. The electronic communication of claim 9, wherein the electronic communication is transmitted from a mobile station (132) to an unlicensed mobile access network controller (142) in an unlicensed radio access network (102).

11. A computer program embodied on a computer readable medium for limiting redirection of a mobile station (132) in an unlicensed-radio access network (102), comprising:

a code segment for initializing a redirection counter (1206);

a code segment including the redirection counter (1208) in a registration request; and

a code segment for incrementing the redirect counter (1212) each time a redirect response is received in response to the registration request.

12. The computer program of claim 11, wherein the redirection counter is initialized to zero (1206) at a first registration request (1204).

13. The computer program as recited in claim 11, further comprising a code segment that creates the registration request.

14. The computer program of claim 11, further comprising a code segment for sending (1208) the registration request to an unlicensed mobile access network controller (142).

15. The computer program as recited in claim 11, further comprising a code segment for receiving a response (1210) to the registration request.

16. A computer program embodied on a computer readable medium for limiting redirection of a mobile station (132) in an unlicensed-radio access network (102), comprising:

a code segment for receiving a registration request (1304) including a redirection counter;

a code segment for normally processing the registration request (1308) as long as the redirection counter does not exceed a certain value; and

a code segment that sends a rejection response (1310) whenever the redirection counter exceeds the value.

17. The computer program of claim 16, further comprising a code segment for creating a log (1312) whenever the redirect counter exceeds the value.

18. The computer program of claim 16, further comprising a code segment that creates the reject response.

19. An apparatus for limiting redirection of one or more mobile stations (132) within an unlicensed-radio access network by using a redirection counter to determine whether to deny a registration request (663 or 667).

20. An unlicensed-radio access system (102) connected to a core network (104) portion of a licensed mobile network, the unlicensed-radio access system (102) including one or more access points (134) adapted to communicate with mobile stations (132) over an unlicensed-radio interface, one or more unlicensed mobile access point controllers (142) connected to the core network (104) portion of the licensed mobile network, and a fixed broadband network (148) connected to the access points (134) and the unlicensed mobile access point controllers (142), wherein the one or more unlicensed mobile access point controllers (142) limit redirection of the mobile stations (132) using a redirection counter in each registration request (663 or 667) of the mobile stations (132).