HK1065215B

HK1065215B - Partial support of mobility between radio access networks

Info

Publication number: HK1065215B
Application number: HK04107941.1A
Authority: HK
Inventors: Palm Hakan; Willars Per
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2001-02-13
Filing date: 2002-02-12
Publication date: 2006-08-18

Description

Partial support for mobility between radio access networks

Background

[0001] The present application claims benefit and priority from the following applications (all of which are incorporated herein by reference in their entirety): U.S. provisional patent application No.60/268,065 entitled "handover using a user-associated neighbor cell list in a shared radio access network environment", filed on 13/2/2001; U.S. provisional patent application No.60/301,442 entitled "Partial support of mobility between radio access networks," filed on 29.6.2001; U.S. patent application No.09/932,447 entitled "Transmission of Filtering/Filter information over the Iur interface" filed on 20.8.2001; U.S. provisional patent application No.60/329,503 entitled "Coordinated subscriber access processing for shared network support", filed on 17.10.2001; and U.S. provisional patent application No.60/330,708 entitled "Coordinated subscriber access handling for shared network support," filed on 29.10.2001.

1. Field of the invention

[0002] The present invention relates to wireless telecommunications, and in particular to roaming of mobile user equipment Units (UEs).

2. Correlation techniques and other considerations

[0003] In a typical cellular radio system, mobile user equipment Units (UEs) communicate through a Radio Access Network (RAN) to one or more core networks. The user equipment Unit (UE) may be a mobile station such as a mobile telephone ("cellular" telephone) and a laptop with a mobile terminal, and thus it may be a portable, pocket, hand-held, computer-included, or car-mounted mobile device that communicates voice and/or data with a radio access network, for example.

[0004] A Radio Access Network (RAN) covers a geographical area which is divided into cell areas, each of which is served by a base station. A cell is a geographical area in which radio coverage is provided by radio base station equipment at a base station site. Each cell is identified by a unique identity, which is broadcast in the cell. The base stations communicate over the air interface (e.g., radio frequencies) with user equipment Units (UEs) that are within range of the base stations. In a radio access network, several base stations are typically connected (e.g. by landlines or microwave) to a Radio Network Controller (RNC). A radio network controller, sometimes referred to as a Base Station Controller (BSC), supervises and coordinates various activities of the base stations connected to it. The radio network controller is typically connected to one or more core networks.

[0005] An example of a radio access network is the Universal Mobile Telecommunications (UMTS) terrestrial radio access network (UTRAN). UMTS is a third generation system that is based in some respects on a radio access technology developed in europe and known as global system for mobile communications (GSM). The UTRAN is actually a wideband code division multiple access (W-CDMA) system. An effort called the third generation partnership project (3GPP) is seeking to further develop the UTRAN.

[0006] As will be appreciated by those skilled in the art, in W-CDMA technology, a common frequency band enables simultaneous communication between a user equipment Unit (UE) and multiple base stations. The signal occupying the common frequency band is identified at the receiving station by a spread spectrum CDMA waveform property based on the use of a high speed code, such as a Pseudo Noise (PN) code. These high speed PN codes are used to modulate signals transmitted from base stations and user equipment Units (UEs). Transmitting stations using different PN codes (or PN code offsets in time) produce signals that can be separately demodulated at the receiving station. High speed PN modulation also allows a receiving station to advantageously generate a received signal from a single transmitting station by combining several different propagation paths of the transmitted signal. Therefore, in CDMA, a user equipment Unit (UB) does not need to switch frequencies when a connection is handed off from one cell to another. As a result, the destination cell may support the connection to the user equipment Unit (UE) while the original cell continues to serve the connection. Since a user equipment Unit (UE) always communicates through at least one cell during handover, the call is not interrupted. Therefore, it is called "soft handover". In contrast to hard handoff, soft handoff is a "make before break" handoff operation.

[0007] A Radio Network Controller (RNC) controls the UTRAN. To fulfill its control role, the RNC manages the resources of the UTRAN. Such resources managed by the RNC include, among other things, the Downlink (DL) power transmitted by the base station; uplink (UL) interference perceived by the base station; and hardware located at the base station.

[0008] There are several interfaces of interest in UTRAN. The interface between the Radio Network Controller (RNC) and the core network is referred to as the "Iu" interface. The interface between a Radio Network Controller (RNC) and its Base Stations (BSs) is called the "Iub" interface. The interface between a user equipment Unit (UE) and a base station is referred to as the "air interface" or "radio interface" or "Uu interface". In some cases, a radio connection involves a serving or Source Rnc (SRNC) and a target or Drift Rnc (DRNC), the SRNC controlling the radio connection, but one or more radio links of the radio connection being handled by the DRNC. The interface between radio network controllers (e.g., between a serving RNC [ SRNC ] and a drift RNC [ DRNC ]) is referred to as the "Iur" interface, which can be implemented, for example, by an inter-RNC transport link.

[0009] Those skilled in the art will appreciate that for a particular RAN-UE connection, an RNC can function as a serving RNC (srnc) or as a drift RNC (drnc). If the RNC is a serving RNC (srnc), the RNC is responsible for the radio connection with the user equipment Unit (UE), e.g. it completely controls the radio connection within the Radio Access Network (RAN). The serving rnc (srnc) is connected to the core network. On the other hand, if the RNC is a drift RNC (drnc), it supports the serving RNC (srnc) by providing the radio resources (within the cell controlled by the drift RNC (drnc)) required for the radio connection with the user equipment Unit (UE). A system comprising a Drift Radio Network Controller (DRNC) and base stations controlled by the Drift Radio Network Controller (DRNC) over an Iub interface is referred to herein as a DRNC subsystem or DRNS.

[00010] When a radio connection is established between a Radio Access Network (RAN) and a user equipment Unit (UE), the Radio Access Network (RAN) decides which RNC is the serving RNC (srnc) and, if desired, which RNC is the drift RNC (drnc). Typically, when a radio connection is first established, the RNC controlling the cell in which the user equipment Unit (UE) is located is initially selected as the serving RNC (srnc). As the user equipment Unit (UE) moves, the radio connection may be maintained even though the user equipment Unit (UE) may move to a new cell, and possibly even to a new cell controlled by another RNC. The other RNC becomes a drift RNC (drnc) for RAN-UE connections. An RNC is said to be the controlling RNC (crnc) for the base stations connected to it over the Iub interface. The role of this CRNC is not UE-specific. The CRNC is in particular responsible for handling the radio resource management of the cells in the base stations connected to it by the Iub interface.

[00011] In some cases it may be advantageous to transfer control of a particular UE connection from one RNC to another. Such transfers of control over the UE connection from one RNC to another are referred to as soft RNC handovers, SRNC concessions (moveover) and SRNC relocation. A relocation function/process is provided to implement this control transfer. This is a general function/procedure covering UMTS internal relocation (e.g. relocation of SNRC within UMTS) and relocation for other systems (e.g. from UMTS to GSM). SRNC relocation is described in various references including the following exemplary commonly assigned patent applications (all of which are incorporated herein by reference).

[00012] (1) U.S. patent application Ser. No.09/035,821 entitled "telecommunication Inter-Exchange Measurement Transfer," filed on 6/3/1998;

[00013] (2) U.S. patent 6,233,222 entitled "Telecommunications Inter-exchange Congestion Control";

[00014] (3) U.S. patent 6,246,878 entitled "Multistage Diversity Handling For CDMA mobile Telecommunications";

[00015] (4) U.S. patent 6,230,013 entitled Diversity Handling mobile For CDMA mobile Telecommunications Diversity Handling assignment;

[00016] (5) U.S. patent application Ser. No.09/732,877 entitled "Control node Handover In Radio Access Network" filed on 12/11/2000;

[00017] (6) U.S. patent application Ser. No.09/543,536, entitled "Relocation of serving Radio Network Controller With Signaling of Linking of differentiated Transport Channels", filed on 5.4.2000;

[00018] (7) U.S. patent application serial No.09/829,001, entitled "Connection Handling in SRNC Relocation" filed on 10/4/2001.

[00019] SRNC relocation is intended to make the transport network more efficiently used. Once the previous SRNC is not needed, the connection to the core network is moved and the connection between the two RNCs (the previous SRNC and the previous DRNC over the inter-RNC link) is disconnected.

[00020] For each mobile station served by the SRNC, the SRNC stores a bit string that permanently identifies the mobile station. According to the RAN system specified by the third generation partnership project (3GPP), this bit string is the IMSI and it is transferred from the CN to the SRNC over the Iu interface at connection setup using the common ID procedure. In the 3GPP approach, the structure of the IMSI is not recognized or used by the SRNC. It is only used to coordinate paging from one CN domain with ongoing connections (matching two bit strings) for another CN domain. The CRNC stores cell information for all cells it controls.

[00021] Currently, the third generation partnership project (3GPP) foresees some collaboration between mobile network operators. For example, two (or more) operators may each have their own operator network (e.g., public mobile network [ PLMN ]), which cooperate together in some parts of the coverage area (e.g., rural areas) but compete in other areas (e.g., urban areas). In 3GPP parlance, two networks are defined as "equivalent PLMNs" in terms of cell selection procedures with respect to the mobile terminal. This equivalence for cell selection enables the terminal to select a cell of a network different from the operator network to which the mobile terminal subscribes.

[00022] For example, as shown in fig. 1, a first operator's network may have cells (represented by the solid circles of fig. 1) that primarily serve or cover the north half of the country (e.g., above line L in fig. 1), while a second operator's network may have cells (represented by the dashed circles of fig. 1) that primarily serve or cover the south half of the country (e.g., below line L in fig. 1). Also, both the first operator and the second operator may serve a competitive area (e.g., a city) outlined by line C of fig. 1 (e.g., both operators have cells in the city/metropolitan area). The first and second operators should co-operate at least to such an extent that a mobile terminal of a user of the first operator should be able to establish mobile communication using a cell of the second operator when walking out of the network of the first operator (e.g. below line L) and vice versa.

[00023] Importantly, one of the operators (such as the first operator) may not want a mobile terminal subscribed to the other operator's network to use a cell (e.g., of the first operator) in an area where both operators have competing cells. For example, a first operator of fig. 1 may not wish a mobile terminal (UE) subscribed to a network of a subscribing operator (e.g., a second operator network in the case of fig. 1) to use a cell of the first operator network when the UE moves to the contention area C. Assuming that in the competition area C of fig. 1 the cell size of the first operator's (solid line) cells is small and that in the competition area C the first operator provides a larger number of cells, the first operator is likely to invest much more in the radio access network infrastructure than the second operator, providing better signal reception, traffic capacity or coverage than the second operator. For these or other reasons, the first operator may wish to prevent a mobile terminal (which subscribes to the network of the competing second operator) from using the (possibly better quality) cell of the first operator, particularly because the second operator has provided the competing cell in the same area.

[00024] For idle mode mobile terminals, the concept of "forbidden LAs" (e.g., forbidden location areas) results in denial of access. When the mobile terminal is informed that certain Location Areas (LAs) are forbidden, the mobile terminal has to look for another LA (and eventually select its own PLMN). Furthermore, the mobile terminal also stores a list of forbidden LAs that is used to avoid selecting a forbidden LA in the future when the mobile terminal is in its idle mode.

[00025] Although access denial is currently feasible for idle mode mobile terminals, there is now no way to prevent a terminal in connected mode belonging to a competitor network from accessing a cell of another network. So, what happens is: a first operator may invest heavily (in a competitive area) to provide high quality coverage, while a competing second operator may try to save money by providing poor coverage, since subscribers to the second operator's network may still reuse the coverage of the other first operator's network. Such considerations undermine effective competition and collaboration.

[00026] What is needed, therefore, and an object of the present invention, is a technique for preventing or denying access to a cell of a first operator's network attempted by or on behalf of a mobile terminal subscribed to a network of a second operator in a contention area.

Summary of The Invention

[00027] Typically, the radio access network of the secondary (first) operator network has cells that are eligible for utilization by user equipment Units (UEs) that are in connected mode and are subscribed to the network of one subscribed (second) operator. However, the present invention prevents or denies attempted utilization (by a user equipment Unit (UE) subscribed to its subscribed operator network) of a restricted cell, which is any cell of the secondary operator network for which the subscribed operator network has a competing cell. The rejected attempted utilization may be one of the following two: (1) handover to a restricted cell, and (2) cell/URA update by the user equipment unit over the restricted cell. Also, preventing attempted utilization of the restricted cell occurs when a user equipment Unit (UE) attempts cell reselection. Thus, in an exemplary implementation, the rejection/blocking is around a user equipment Unit (UE) in a connected mode in one of the following states: a cell _ DCH state, a cell _ FACH state, a cell _ PCH state, and a URA _ PCH state; and URA _ PCH state.

[00028] In its various aspects, the invention relates to a radio access network that performs the rejections necessary to protect a restricted cell, to a control node of such a radio access network and to an operator filter of such a control node.

[00029] When a handover is attempted to a target cell of a secondary operator network for a user equipment Unit (UE) subscribed to the subscribed operator network, a protection control node of the secondary operator network obtains from the originating operator network an International Mobile Subscriber Identity (IMSI) of the user equipment Unit (UE) and an identity of the target cell sought by the handover. The protection control node uses the IMSI to determine whether the target cell is a restricted cell and (if so) informs the originating operator network: the handover is rejected. The International Mobile Subscriber Identity (IMSI) of the user equipment Unit (UE) and the identity of the target cell sought for handover may be derived from the Source Radio Network Controller (SRNC) of the originating operator network. When the user equipment Unit (UE) is in the cell _ DCH state, in one illustrated embodiment, the International Mobile Subscriber Identity (IMSI) of the user equipment Unit (UE) and the identity of the target cell are specifically derived from a RL SETUP REQUEST message issued by the Source Radio Network Controller (SRNC) of the originating operator network. In determining whether the target cell is a restricted cell, a protection control node of the secondary operator network derives a PLMN code from the IMSI of the user equipment Unit (UE), and consults a table to determine (from the derived PLMN code) whether the target cell is eligible for handover of the user equipment Unit (UE).

[00030] In addition to or in conjunction with the attempted handover, the second operator network may also attempt to perform a handover known as a hard handover through SRNC relocation, which (in the context of the present invention) is the transfer of the SRNC role from the radio network controller of the subscribing operator network to the Radio Network Controller (RNC) of the secondary operator network. In such a scenario, the protection control node of the secondary operator network obtains from the core network the International Mobile Subscriber Identity (IMSI) of the user equipment Unit (UE) and the identity of the target cell. The protection control node then determines whether the target cell is a restricted cell (in a similar manner to handover evaluation/rejection) and (if so) informs the core network: handovers with relocation are rejected. In the shown implementation, the protection control node derives the International Mobile Subscriber Identity (IMSI) of the user equipment Unit (UE) and the identity of the target cell from a RELOCATION REQUEST message of the core network.

[00031] The present invention has broad applicability regardless of which network the SRNC is located in (e.g., regardless of the identity of the originating operator network). For example, the source RNC may be within a subscribed operator network. Alternatively, the source SRNC may be in the secondary (first) operator network (e.g., the inventive procedure is used between two radio network controllers of the secondary operator network). Furthermore, the source SRNC may be in another country (e.g. a third operator network) while the mobile terminal (UE) is only moving into one area of two cooperating/competing operator networks.

[00032] The attempted utilization may also be an attempted cell update performed by a user equipment Unit (UE) through the restricted cell. Typically, when performing a Cell update, a user equipment Unit (UE) is either in a Cell _ FACH state or in a Cell _ PCH state. When a user equipment Unit (UE) attempts to perform a cell update to a target cell of a secondary operator network, the protection control node also derives from the subscribed operator network an International Mobile Subscriber Identity (IMSI) of the user equipment Unit (UB) and an identity of the target cell. The protection control node then determines whether the target cell is a restricted cell, and (if so) gives a notification that the cell update is rejected, in a similar manner to the attempted handover. In an example implementation, in connection with the attempted cell update, the protection control node receives an International Mobile Subscriber Identity (IMSI) of the user equipment Unit (UE) and an identification of the target cell from a COMMON TRANSPORT channel resources REQUEST (COMMON TRANSPORT channel resources REQUEST) message issued by a Source Radio Network Controller (SRNC) of the subscribed operator network.

[00033] Blocking attempted utilization of the restricted cell may also occur when a user equipment Unit (UE) attempts cell reselection. In the exemplary embodiment shown, cell reselection attempted by the user equipment Unit (UE) may occur when the user equipment Unit (UE) is in a cell _ PCH state, or a cell _ FACH state, or a URA _ PCH state. When a user equipment Unit (UE) attempts to utilize the restricted cell, the secondary operator network causes an identification of the restricted cell to be transmitted from the first operator network to the user equipment Unit (UE).

[00034] In one aspect of the invention, the invention relates to a mobile terminal that subscribes to its home operator network and checks whether a target cell is a restricted cell in connected mode and before proceeding with cell reselection to the target cell. Here again, the restricted cell is considered to be operated by an operator network of a secondary or foreign country, and is in competition with a cell operated by an operator network of a home country or subscription. In an exemplary embodiment, location area identity codes (LAIs) broadcast from each cell are used and the mobile terminal maintains a list of restricted location area identity codes which are consulted as part of the check. In one exemplary mode, the mobile terminal updates the list of restricted LAIs when location registration through the restricted cell to the core network is rejected by the core network with information rejecting this LAI. In another exemplary mode, the mobile terminal updates the list of restricted LAIs when a rejection of the attempted cell update is received, which includes information that this LAI is restricted. Another example is that the mobile terminal maintains a list of restricted cells and after rejecting the cell update, the mobile terminal is informed by the network: the particular cell is restricted. After the mobile terminal finds that the target cell is restricted, the mobile terminal no longer attempts to access the cell, but searches for other cells.

Brief Description of Drawings

[00035] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of preferred embodiments as illustrated in the accompanying drawings wherein like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

[00036] Fig. 1 is a schematic diagram showing a network topology for illustrating a first scenario of the present invention, the network topology comprising two operator networks (PLMNs) that cooperate together in some geographical area and compete with each other in another geographical area.

[00037] Fig. 1A is a schematic diagram showing a network topology for illustrating a second scenario of the present invention.

[00038] Fig. 1B is a schematic diagram showing a network topology for explaining a third scenario of the present invention.

[00039] Fig. 2 is a schematic diagram of portions of an exemplary representative telecommunications system that serves as an example of a non-limiting implementation of embodiments of the present invention.

[00040] Fig. 3 is a schematic diagram showing various aspects of a user equipment Unit (UE) and certain basic aspects of a base station node and a radio network control node.

[00041] Fig. 4 is a schematic diagram showing a connected mode state of a user equipment Unit (UE) related to the present invention.

[00042] Fig. 5A and 5B are partly schematic and partly diagrammatic views showing various modes of the solution part of the invention for evaluating and, if necessary, rejecting a handover attempt.

[00043] Fig. 6A (1), fig. 6A (2), fig. 6B (1) and fig. 6B (2) are partly schematic and partly diagrammatic views showing various modes of the invention for one cell update attempt and the solution portion of rejecting one cell update attempt if necessary.

[00044] Fig. 7 is a schematic diagram of a representative RNC node example that may be utilized in the implementation of the present invention.

[00045] Fig. 8 is a schematic diagram showing the storage of a copy of the PLMN/area table of the CRNC at the SRNC node.

Detailed Description

[00046] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, interfaces, techniques, etc. in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail. Moreover, individual functional blocks are shown in some of the figures. Those skilled in the art will appreciate that the functions may be implemented using individual hardware circuits, using software functioning in conjunction with a suitably programmed digital microprocessor or general purpose computer, using an Application Specific Integrated Circuit (ASIC), and/or using one or more Digital Signal Processors (DSPs).

[00047] Returning to the illustration of fig. 1, the first operator network (drawn with solid line cells) will be referred to as the secondary operator network (e.g., PLMN), while the operator network drawn with dashed line cells will be referred to and considered as "subscribing" to the operator network in the following sense: in the following discussion, a mobile terminal in a connected mode is the subject of a subscription contract with a subscription network. As previously mentioned, the term user equipment Unit (UE), as used herein, is intended to include all types of mobile terminals.

[00048] Outside the contention region C, the cells of the first (secondary) operator network are eligible for utilization by user equipment Units (UEs) that are in connected mode and subscribe to their subscribed operator networks. However, the present invention prevents or denies attempts by a user equipment Unit (UE) subscribing to another operator network (e.g., a subscription to a (second) operator network) to utilize restricted cells of a first operator network. A restricted cell is any cell of the secondary operator network for which the subscribing operator network has a competing cell, e.g., a cell in competing area C. As explained in more detail hereinafter, the rejection of attempted exploitation may be one of the following two: (1) handover to restricted cell, and (2) cell/URA update by the user equipment Unit (UE) through the restricted cell. Also, blocking attempts to utilize the restricted cell occurs when a user equipment Unit (UE) attempts cell reselection. Thus, rejection/blocking is around a user equipment Unit (UE) in connected mode in one of the following states: a cell _ DCH state, a cell _ FACH state, a cell _ PCH state; and URA _ PCH state.

[00049] Before describing the inter-network contention/cooperation features of the present invention, a brief description of selected portions of an illustrative implementation of an exemplary radio access network is given. Fig. 2 shows an illustrative, non-limiting example implementation in the context of a Universal Mobile Telecommunications (UMTS) 10.

[00050] The representative, connection-oriented, external core network shown as cloud 12 of fig. 2 may be, for example, a Public Switched Telephone Network (PSTN) and/or an Integrated Services Digital Network (ISDN). The representative, connectionless external core network shown as cloud 14 may be, for example, the internet. Both core networks are coupled to respective service nodes 16. The PSTN/ISDN, etc. connection-oriented network 12 is connected to a connection-oriented service node, shown as a Mobile Switching Center (MSC) node 18 that provides circuit-switched services. The internet or like connectionless-oriented network 14 is connected to a General Packet Radio Service (GPRS) node 20, sometimes referred to as a Serving GPRS Service Node (SGSN), that is customized to provide packet-switched type services.

[00051]Each of the core network service nodes 18 and 20 is connected to the UMTS Terrestrial Radio Access Network (UTRAN) over a Radio Access Network (RAN) interface known as the Iu interface. The UTRAN includes one or more Radio Network Controllers (RNCs) 26. For simplicity, the UTRAN of FIG. 2 is shown with only two RNC nodes, specifically RNC 26₁And RNC 26₂. Each timeThe RNCs 26 are connected to a plurality of Base Stations (BSs) 28. For example, again for simplicity, two base station nodes are shown connected to each RNC 26. In this regard, the RNC 26₁Serving base station 28_1-1And base station 28_1-2And RNC 26₂Serving base station 28_2-1And base station 28_2-2. It will be appreciated that each RNC may serve a different number of base stations, and that the RNCs need not serve the same number of base stations. Also, fig. 2 shows that an RNC may be connected to one or more other RNCs in the UTRAN through an Iur interface.

[00052] In the illustrated embodiment, each base station 28 is shown to serve one cell for simplicity. Each cell is represented by a circle surrounding the respective base station. However, those skilled in the art will appreciate that a base station may be used to provide communications over the air interface for more than one cell. For example, two cells may utilize resources located at the same base station site.

[00053] A user equipment Unit (UE), such as user equipment Unit (UE)30 shown in fig. 2, communicates over a radio or air interface 32 with one or more cells or one or more Base Stations (BSs) 28. Each of the radio interface 32, Iu interface, Iub interface, and Iur interface is represented by a dashed line in fig. 2.

[00054] Preferably, the radio access is based on Wideband Code Division Multiple Access (WCDMA) with individual radio channels allocated using CDMA spreading codes. Of course other access methods may be employed. WCDMA provides wide bandwidth for multimedia services, other high transmission rate requirements, and robust features such as diversity switching and RAKE receivers to ensure high quality. In the cell _ DCH state, each user mobile station or equipment Unit (UE)30 is assigned its own scrambling code so that the base station 28 recognizes transmissions from that particular user equipment Unit (UE) and causes that user equipment Unit (UE) to recognize transmissions that the base station intends for that user equipment Unit (UE) from all other transmissions and noise present in the same area.

[00055] There may be different types of channels between one of the base stations 28 and a user equipment Unit (UE)30 for communicating control and user data. For example, in the forward or downlink direction, there are several types of broadcast channels, including the general Broadcast Channel (BCH), the Paging Channel (PCH), the common pilot channel (CPICH), and the Forward Access Channel (FACH), which are used to provide various other types of control messages to user equipment Units (UEs). The Forward Access Channel (FACH) is also used to carry user data. In the reverse or uplink direction, the Random Access Channel (RACH) may be employed by a user equipment Unit (UE) whenever access is desired to perform location registration, initiate a call, answer paging, and other types of access operations. The Random Access Channel (RACH) may also be used to carry certain user data, for example best effort packet data for web browsing applications. A Dedicated Channel (DCH) may be allocated to carry a large number of call communications with a user equipment Unit (UE).

[00056] In particular, the present invention, which may be implemented in the exemplary context of the telecommunications system of fig. 2, relates to new and improved techniques for facilitating collaboration and competition between operator networks. As one aspect of implementing this new technique, one or more radio network controllers 26 perform network protection functions, and therefore, are referred to herein as "protection" nodes or "protection" control nodes. Thus, as an illustrative, non-limiting example implementation, the radio network controller 26 of fig. 2 is shown as a network protection filter 100. As described in more detail below, this protection function, e.g., implemented by the network protection filter 100, prevents or denies attempts by the user equipment Unit (UE)30 to utilize restricted cells of the first (secondary) operator network, assuming that the user equipment Unit (UE)30 is subscribed to another operator network (e.g., a subscribed (second) operator network).

[0001] Fig. 3 shows selected general aspects of a user equipment Unit (UE) and illustrative nodes, such as the radio network controller 26 and the base station 28. The user equipment Unit (UE) shown in fig. 3 includes a data processing and control unit 31 for controlling various operations required by the user equipment Unit (UE). The data processing and control unit 31 of the UE provides control signals as well as data to a radio transceiver 33 connected to an antenna 35. The user equipment Unit (UE)30 may have user interactive or user viewable devices such as an input device 310 and a display device 312, among other functions described hereinafter.

[00057] The exemplary radio network controller 26 and base station 28, as shown in fig. 3, are radio network nodes that each include a respective data processing and control unit 36 and 37, respectively, for performing various radio and data processing operations required for directing communications between the RNC 26 and the user equipment Unit (UE) 30. Part of the equipment controlled by the base station data processing and control unit 37 comprises a plurality of radio transceivers 38 connected to one or more antennas 39.

[00058]Figure 7 shows an exemplary non-limiting RNC node 26 of the present invention in more or less detail_G. The RNC node 26 of fig. 7_GCan represent a Serving RNC (SRNC) or a Drift RNC (DRNC). Sometimes the RNC node 26 of fig. 7_GIs a switch-based node with a switch 120. The switches are used to interconnect the RNC nodes 26_GOther constituent units of (1). Such other elements include an extended terminal [ ET ]]125_G-1To 125_G-nRNC node 26 by inter-RNC link_GExtension terminal 125 connected to another radio network controller_G(ii) a And an extension terminal 124. Extended terminal [ ET]125_G-1To 125_G-nActually serving to connect the RNC node 26_GConnected to the RNC node 26_GA serving base station 28; extension terminal 124 connects RNC node 26 via Iu interface_GIs connected to the core network 16. RNC node 26_GComprises a diversity switching unit 27_GA codec 130, a timing unit 132, a data service application unit 134, and a main processor 140. In an exemplary non-limiting RNC node 26_GNetwork protection filter 100 is shown as being implemented in host processor 140. It should be understood, however, that the network protection filter 100 may be implemented using software functioning in conjunction with a suitably programmed digital microprocessor or general purpose computer by using separate hardware circuitsThe elements are implemented using Application Specific Integrated Circuits (ASICs), and/or using one or more Digital Signal Processors (DSPs).

[00059] The implementation example of fig. 2 thus serves as an exemplary network whose structure may be adopted by one or more secondary (first) operator networks and a subscription (second) operator network. It should be understood, however, that such structural examples do not limit the present invention.

[00060] As mentioned above, the problem is that the prior art does not provide any network protection for the user equipment Unit (UE) in its connected mode. The present invention overcomes this problem with three solutions. For the embodiment shown, these solutions are described below diagrammatically in 3GPP terminology. The 3GPP terminology includes knowledge of the various states that a user equipment Unit (UE) in its connected mode gets. Four of these states (cell _ DCH state, cell _ FACH state, URA _ PCH state, and cell _ PCH state) are germane to the present invention. These closely related 3GPP connected mode states are shown in fig. 4, and each state is described briefly below. Each connected mode state reflects a different activity level.

[00061] The cell _ DCH state is characterized by a Dedicated Channel (DCH) assigned to a user equipment Unit (UE). Macro diversity may be used between DCHs of several cells. In the cell _ DCH state, there is a Dedicated Control Channel (DCCH) for transmitting signaling messages between the user equipment Unit (UE) and the UTRAN.

[00062] In the cell _ FACH state, no dedicated physical channel is assigned, but the user equipment Unit (UE) continuously listens to the common channel (FACH) on the downlink belonging to the selected cell. On the uplink, a user equipment Unit (UE) typically uses a Random Access Channel (RACH). At each cell reselection, the user equipment Unit (UE) updates the network with its current cell location. In this state, there is a Dedicated Control Channel (DCCH) for transmitting signaling messages between the user equipment Unit (UE) and the UTRAN. The DCCH is implemented by attaching a radio network temporary identity (U-RNTI or C-RNTI) to all signaling messages, thereby addressing individual UEs. U-rnti (UTRAN rnti) is a global identity that can be used for any cell in UTRAN. C-rnti (cell rnti) is only important in a single cell and it has to be reallocated in each cell. On the other hand, the C-RNTI is much shorter than the U-RNTI, which when used will save space on the radio interface. There is also a CCCH (common control channel) in this state, which is used when the connection to the SRNC cannot be provided, such as after CELL reselection at the RNC border, when a CELL UPDATE or URA UPDATE message is sent to the DRNC.

[00063] In the cell _ PCH state, a user equipment Unit (UE) monitors a Paging Channel (PCH) of a selected cell. On the PCH, the user equipment Unit (UE) uses Discontinuous Reception (DRX) to save power, and the scheme for when to listen is negotiated between the network and the user equipment Unit (UE) on a per user equipment Unit (UE) basis. In addition, in the CELL _ PCH state, the user equipment Unit (UE) updates the network with the current CELL location at the time of CELL reselection. No DCCH may be provided in the cell _ PCH state. On the PCH there is a method for addressing an individual user equipment Unit (UE) (using U-RNTI), but the user equipment Unit (UE) cannot transmit any signaling messages to the network.

[00064] The URA _ PCH state is almost identical to the cell _ PCH state. The difference is that the user equipment Unit (UE) updates the network with its location only after crossing the URA border. URA (UTRAN registration area) is a set of cells. This means that in this state the location of the user equipment Unit (UE) is typically only known on the URA level.

[00065] Having briefly described the connected mode state for a user equipment Unit (UE), the solution proposed by the present invention will be introduced:

[00066] (1) the first solution is that the UE cannot switch to a cell of the competing network in the competing area in the celldch state.

[00067] The second part of the solution is that the secondary (first) operator network can reject the UE access (cell update) to the cells of the competing network in the competing area in either cell _ FACH or cell _ PCH state.

[00068] (3) the third solution is that the UE has the function of avoiding the selection of a cell of a competing network in a competing area in the cell _ FACH or cell _ PCH state, even if this network is "equivalent" from the cell selection point of view.

[00069]Each of these resolution parts is discussed separately below using an illustration (such as fig. 5). On fig. 5A and on each of the following illustrations, the nodes of the secondary (first) operator network are shown with solid lines, while the nodes of the originating operator network are shown with dashed lines. The originating operator network is the network that requests the SRNC relocation or the handover with relocation. Also, ON these illustrations, any subscript including "O1" refers to an aspect of the secondary (first) operator network, while any subscript including "ON" refers to an aspect of the originating operator network. Furthermore, a radio network controller 26 of the secondary (first) operator network_O1Currently referred to as CRNC, while subscribing to the radio network controller 26 of the (second) operator network_ONCurrently referred to as SRNC. The inter-RNC link is shown as the radio network controller 26 connecting the secondary (first) operator network_O1Radio network controller 26 with the originating operator network_ON。

[00070]The present invention has wide applicability regardless of the radio network controller 26_ONWhich network may belong to or be located (e.g., regardless of the identity of the originating operator network). For example, in the scenario illustrated in fig. 1, the originating operator network can be the subscribing operator network, and thus the source SRNC is within the subscribing operator network. Alternatively, as shown in fig. 1A, the source SRNC may be in a secondary (first) operator network (e.g., the procedures of the present invention may be used between two radio network controllers within the secondary operator network). Further, as shown in fig. 1B, the source SRNC may belong to an originating operator network in another country (e.g., the originating operator network is a third operator network [ not a secondary operator network and a subscribing operator network ]]) Mobile terminalThe end (UE) simply moves from the (foreign) originating operator network to the area of two cooperating/competing operator networks (the secondary operator network and the subscribing operator network). Thus, it should be appreciated that the notation (e.g., subscript) "ON" as employed herein is not limited to referring to any particular originating operator network, but may refer to, for example, an auxiliary operator network (e.g., ON ═ O1), or a subscribing operator network, or a third party or any other operator network.

[00071]As previously mentioned, the radio network controller 26 of the secondary (first) operator network_O1With a network protection filter 100. As shown in fig. 5A and the various subsequent figures, the network protection filter 100 includes a table 110 or other stored indication or list that can be consulted to determine (based on the derived PLMN code) whether the action taken with respect to the target cell of the secondary (first) operator network is permissible.

[00072]Table 110 is also referred to hereinafter as PLMN/area table 110. As will be seen from the description that follows, the radio network controller 26 of the (first) operator network is assisted in certain circumstances involved in the solution scenario_O1The network protection filter 100 of (1) is provided to the IMSI of a connected mode user equipment Unit (UE) involved in a potential or attempted action (e.g., handover, yield (moveover), cell update), and the identity of the target cell. As will be seen by those skilled in the art, an IMSI is an international mobile subscriber identity, which is a unique identity assigned to each subscriber, which facilitates correct subscriber identification on the radio path or throughout the network. The IMSI is typically a concatenation of a Mobile Country Code (MCC), a Mobile Network Code (MNC) and a Mobile Station Identity (MSI).

[00073]In the above respect, in various embodiments of the invention, the network protection filter 100 derives the PLMN code (e.g., mobile country code MCC) from the IMSI]And mobile network code MNC]Combinations of (ii). The network protection filter 100 then consults the PLMN/area table 110 to determine whether the action sought or attempted is permitted by the secondary (first) operator network. For example, the network protection filter 100Using the PLMN code as an index for accessing the PLMN/area table 110 and determining from the table 100 the radio network controller 26 for the secondary (first) operator network_O1Which areas (e.g., cells) of control, the sought or attempted action is permitted. The network protection filter 100 then searches the area list derived from the table to determine whether the target cell is listed within or contained within an area on the list. For example, in the illustration of fig. 5A, PLMN/area table 110 includes a list of licensed areas for which actions of a user equipment Unit (UE) subscribing to the (second) operator network are licensed.

[00074] Variations of the PLMN/area table 110 are of course possible. For example, the PLMN/area table 110 may list forbidden areas instead of allowed areas. In either case, the eligibility status of the cell can be easily derived or inferred.

[00075]The "area" that is the subject of table 110 (which may be licensed or forbidden) may be any conventional geographic or network-based element, such as a cell or Location Area (LA). As will be appreciated by those skilled in the art, a cell is the basic unit of a cellular system, which is the geographical area covered by a base station. The Location Area (LA) is a group of cells, each having an independent Location Area Identity (LAI). Base stations within a location area periodically broadcast the LAI of the particular location area in which they are located. In the event that the table 110 of the network protection filter 100 is constructed in terms of Location Areas (LAs), an optional auxiliary table 112 or the like may be used to look up the location area including the target cell (as it is transmitted to the radio network controller 26 of the auxiliary (first) operator network)_O1Target cell of). In at least some embodiments described herein, all cells within a Location Area (LA) should be uniformly barred or uniformly accessible.

[00076] Rejecting handover

[00077]The first part of the solution is that the UE in celldch state cannot switchTo a cell of a competing network in a competing area. In practice, as the RNC controlling the target cell for handover, the radio network controller 26 of the secondary (first) operator network_O1Is made responsible for deciding which UEs are allowed to access the cell under its control. This provides the secondary (first) operator with consistent control over the resources used in the secondary (first) operator network.

[00078] Fig. 5A specifically shows some basic events, actions or steps that occur for one mode of a first solution scenario, e.g., a scenario in which a subscribing operator network attempts to perform a handover of a user equipment Unit (UE) subscribed to the subscribing operator network to a target cell of an assisting operator network. The handover may be a soft handover, e.g. a handover in which the SRNC attempts to add a leg of an existing connection in the target cell.

[00079]As shown by event 5A-1 in fig. 5A, the radio network controller 26 of the secondary (first) operator network_O1An international mobile identity (IMSI) of a user equipment Unit (UE) and an identity of a target cell sought for handover are derived from an originating operator network. In a 3GPP implementation of this scenario, it is assumed that the user equipment Unit (UE) is in a cell _ DCH state, specifically, the international mobile identity (IMSI) of the user equipment Unit (UE) and the identity of the target cell are from the radio network controller 26 of the originating operator network_ONObtained in the RL setup request message sent.

[00080]As event 5A-2, the protection control node uses the IMSI to determine whether the target cell is a restricted cell (e.g., whether this user equipment Unit (UE) is allowed access to the target cell). The determination using the IMSI is made in the manner described above with reference to the exemplary PLMN/area table 110 (e.g., from the user equipment unit UE)]Derives a PLMN code, and a look-up table 110 determines [ from the derived PLMN code ]]Target cell to user equipment unit UE]Whether or not the handover of (b) is eligible). Radio network controller 26 of the secondary (first) operator network if access is not allowed_O1Rejection ofA handover attempt (e.g., RL SETUP REQUEST). As event 5A-3, the radio network controller 26 of the secondary (first) operator network_O1Sending messages to the radio network controller 26 of the originating operator network_ONIndicating the target cell for this user (e.g., user equipment unit [ UE ]]) Is not accessible.

[00081]Fig. 5B likewise shows certain basic events, actions or steps that occur for another mode of the first solution (e.g., a scenario in which a subscribing operator network attempts to perform a type of handover known as a handover with SRNC relocation). Such a mobile handover is, in accordance with the invention, a radio network controller 26 of the SRNC role from the originating operator network_ONRadio network controller 26 to a secondary (first) operator network_O1The transfer of (2).

[00082]In the scenario of FIG. 5B, as event 5B-1, the radio network controller 26 of the originating operator network_ONThe SRNC relocation process is initiated by sending a relocation request message to the core network 16, the relocation request message including the identity of the target cell. Then, in reply, as event 5B-2, the core network 16 is in the target RNC (i.e., at the radio network controller 26 of the secondary (first) operator network)_O1In) request resources for relocation. The request resource message of event 5B-2 includes the international mobile identity (IMSI) of the user equipment Unit (UE) and the identity of the target cell.

[00083]In a similar manner to FIG. 5A, as event 5B-3, the target RNC (i.e., the radio network controller 26 of the secondary (first) operator network)_O1) The PLMN/area table 110 is used to determine whether the user is allowed access to the target cell and whether the relocation can be successful. In the event that relocation is not allowed, the radio network controller 26 of the secondary (first) operator network_O1The attempted relocation is rejected, a message is sent as event 5B-4: the target cell is not accessible to this user/user equipment Unit (UE). On reply, the core network 16 then sends a rejection as event 5B-5Radio network controller 26 of message to originating operator network_ONSuch a reject message also includes a cause value for explaining that the target cell is not accessible to this user/user equipment Unit (UE).

[00084] In one exemplary implementation of FIG. 5B, the message of event 5B-1 is a RELOCATION REQUERED message, and the message of event 5B-2 is a RELOCATION REQUEST message.

[00085] Rejecting cell updates

[00086] The second solution part is: if the user equipment Unit (UE) belongs to a subscribed (second) operator network, the secondary (first) operator network can reject access (cell update and URA update) of the UE in the contention region. A cell update may occur when a user equipment Unit (UE) is in a cell _ FACH or cell _ PCH state; a URA update may occur when a user equipment Unit (UE) is in a URA _ PCH state. As used herein, "update" includes cell update and URA update.

[00087]This second solution part refers to a similar principle as for the cell _ DCH state (see the first solution above, reject HANDOVER), but the solution part is applicable when the connected mode user equipment Unit (UE) is in the cell _ FACH, cell _ PCH or URA _ PCH state, but not in the cell _ DCH state. For this second solution part, use is made of a radio network controller 26 configured in the secondary (first) operator network_O1The same PLMN/area table 110 in the network protection filter 100.

[00088] By way of background, when a user equipment Unit (UE) is using a RACH/FACH common channel (e.g., the UE RRC state is CELL _ FACH), the first message sent from the user equipment Unit (UE) when it enters a new CELL is a CELL update RRC (CELL-update) message. The cell update RRC message serves as a kind of registration message to let the UTRAN know the new location of the user equipment Unit (UE). The UTRAN then decides how to handle this user equipment Unit (UE). If the UTRAN decides that the user equipment Unit (UE) is to remain on the common channel, then the user equipment Unit (UE) will be informed: remaining on the common channel. The user equipment Unit (UE) then monitors any downlink transmissions in the FACH and uses some RACH for uplink access. This situation where a user equipment Unit (UE) uses a common channel is therefore different from the situation where a user equipment Unit (UE) uses a dedicated channel, since the use of a dedicated channel may establish a soft handover situation where a new radio link or connection leg with the user equipment Unit (UE) is established through a new cell. Similarly, a URA update may occur when a user equipment Unit (UE) is in a URA _ PCH state. As mentioned above, the general reference to "update" here includes both/or either of the cell update scenario and the URA update scenario, for which the signaling sequence is substantially the same.

[00089]Various modes of the second solving means are shown in fig. 6A (1), fig. 6A (2), fig. 6B (1), and fig. 6B (2). This second solution part is generally applicable to such situations as: the user equipment Unit (UE), which belongs to a subscription (second) operator network, is not yet aware of a certain cell (e.g. cell or location area LA)]) Is forbidden, and therefore, the user equipment Unit (UE) attempts to perform an update (e.g., to the target cell of the LA). Event 6-1 of fig. 6A (1), 6A (2), 6B (1), and 6B (2) shows that the user equipment Unit (UE) attempts to update to the radio network controller 26 of the secondary (first) operator network_O1The update message of event 6-1 does not include the IMSI of the subscriber (e.g., user equipment Unit (UE)), such that, as in normal operation, the radio network controller 26 of the (first) operator network is assisted as event 6-2_O1Radio network controller 26 that can only include and forward cell update messages to the originating operator's network_ON。

[00090]Upon receiving the update request of event 6-2, the radio network controller 26 of the originating operator network_ONThere are two possible basic responses. The first possible response is to use the Iur connection; a second possible response is to initiate the SRNC relocation. In both of these possibilitiesThe transmission of the rejection to the user equipment Unit (UE) may be implemented in either of two alternatives. The first alternative involves sending a special reject message to the user equipment Unit (UE) for two possible basic responses. A second alternative involves using another message (e.g., an RRC release (RRC RELEASE) message sent from the SRNC to the user equipment Unit (UE) that ultimately has the effect of rejecting the cell update, which causes the user equipment Unit (UE) to attempt an unsuccessful location registration with the core network 16 to know that the cell is barred).

[00091] A first alternative of the first possible response is shown in fig. 6A (1), and a second alternative of the first possible response is shown in fig. 6A (2). A first alternative of a second possible response is shown in fig. 6B (1), and a second alternative of the second possible response is shown in fig. 6B (2).

[00092]Fig. 6A (1) shows a second solution portion mode, in which the SRNC (i.e., the radio network controller 26 of the originating operator network) is in service_ON) Remain in the old network and utilize Iur connections. As event 6A-3, the radio network controller 26 of the originating operator network_ONSending a resource request message to a radio network controller 26 of a secondary (first) operator network_O1The message of event 6A-3 includes the target cell and the IMSI of the subscriber. In the illustrated 3 GPP-based exemplary implementation, the message for event 6A-3 can be a publication to a CRNC (e.g., the radio network controller 26 of the secondary (first) operator network)_O1) The common transport channel resource request message.

[00093]As with the previously described mode, as event 6A-4, the radio network controller 26 of the secondary (first) operator network_O1The network protection filter 100 uses the PLMN/area table 110 to determine whether a user equipment Unit (UE) is allowed access to the target cell. If the user equipment Unit (UE) is not allowed access, then as event 6A-5, the radio network controller 26 of the secondary (first) operator network_O1Radio network control for sending rejection messages to an originating operator networkDevice 26_ONIt is proposed that this cell cannot be accessed by a user equipment Unit (UE). Then, as events 6A (1) -6, the radio network controller 26 of the originating operator network_ONA reject message is sent to a user equipment Unit (UE).

[00094] In the first alternative of fig. 6A (1), the rejection message of events 6A (1) -6 is a message specifically rejecting the update (e.g., a message dedicated to rejecting the update or specifically dedicated to carrying a direct code, domain, or value understood to be rejected). The messages of events 6A (1) -6 specifically indicate that the cell/URA requested for the update belongs to a forbidden area (e.g., a forbidden location area or a forbidden cell). In response, as events 6A (1) -7, the user equipment Unit (UE) stores the cell that elicited the reject message on its forbidden area list 202 (see fig. 3). The user equipment Unit (UE) then attempts to select another cell and will eventually select one of the cells of the originating operator network or otherwise enter its idle mode.

[00095]Fig. 6A (2) shows a second alternative to the mode using the Iur connection that implements rejection of the update. For the case of FIG. 6A (2), events 6-1 and 6-2, and events 6A-3 through 6A-5, are substantially the same as those shown in FIG. 6A (1). However, the second alternative of fig. 6A (2) is different in the way it communicates the rejection of the update to the user equipment Unit (UE). In particular, this second alternative of fig. 6A (2) may occur when a new message for rejecting an update is not available in the secondary (first) operator network or otherwise feasible. In this second alternative of fig. 6A (2), the rejection message of events 6A (2) -6 is an RRC release message. Upon receiving the RRC release message of event 6A (2) -6, the user equipment Unit (UE) enters idle mode and attempts (as event 6A (2) -7) location registration to the core network 16. This location registers the radio network controller 26 via the secondary (first) operator network_O1(e.g., in the case of a cell update) because the user equipment Unit (UE) still considers the target cell to be a valid cell. If the LAI of the new cell is different from the previous one, the user equipment Unit (UE) will trigger only this bitRegistration (which explains why the forbidden or restricted area is preferably the location area LA])。

[00096] The core network 16 has the same information as in the PLMN/area table 110 and, as indicated by the reject message for events 6A (2) -8, it will reject the attempted location registration for events 6A (2) -7. The messages of events 6A (2) -8 indicate that the reason for the rejection is a forbidden area (e.g., forbidden location area LA). Although not shown as such in fig. 6A (2) for simplicity of the figure, the location registration of events 6A (2) -7 and the rejection of events 6A (2) -8 are made by the base station serving the cell involved in the update sought. Upon receiving such rejection, the user equipment Unit (UE) updates its list of forbidden areas 202 (see fig. 3) as events 6A (2) -9. Finally, the user equipment Unit (UE) will select another area (e.g., desirably the area of the subscribed operator network) and perform a successful registration.

[00097]Fig. 6B (1) shows a mode of a second resolution part, in which the SRNC (i.e., the radio network controller 26 of the originating operator network) is in service_ON) Deciding to use handover with SRNC relocation. Fig. 6B (1) shows that events 6-1 to 6-2 in fig. 6 occur in the same manner as in fig. 6A (1), with the result that the radio network controller 26 of the secondary (first) operator network_O1Sending an update message 6-2 to the radio network controller 26 of the originating operator network_ON. Then, as event 6B-3, the radio network controller 26 of the (second) operator network is subscribed to_ONA handover with SRNC relocation procedure is initiated by sending a relocation request message to the core network 16. The relocation request message includes an identification of the target cell. Then, in reply, as event 6B-4, the core network 16 is in the target RNC (i.e., at the radio network controller 26 of the secondary (first) operator network)_O1In) request resources for relocation. The request resource message of event 6B-4 includes the IMSI of the user equipment Unit (UE) and the identity of the target cell/URA.

[00098]In a manner similar to the previous case, as event 6B-5, the target RNC (i.e., assisting)Radio network controller 26 of a (first) operator network_O1) The PLMN/area table 110 is used to determine whether the user is allowed access to the target cell/TRA and whether the mobile handover can be successful. Assisting a target radio network controller 26 of a (first) operator network in the event relocation is not allowed_O1Rejecting the attempt to relocate, as event 6B-6, sends out a message: the target cell is not accessible to this user/user equipment Unit (UE). On reply, as event 6B-7, the core network 16 then sends a rejection message to the radio network controller 26 of the originating operator network_ONSuch a reject message also includes a reason or the like for explaining that the target cell is not accessible to this user/user equipment Unit (UE).

[00099]As with the first mode of the solution of rejecting updates, in the second mode, rejection of the update may be communicated to the user equipment Unit (UE) in either of two alternatives. A first alternative is shown in fig. 6B (1), and it is similar to the communication using the Iur connection in fig. 6A (1). In this first alternative, as events 6B (1) -8, the radio network controller 26 of the originating operator network_ONA reject message is sent to a user equipment Unit (UE). The rejection messages of events 6B (1) -8 are messages that specifically reject the update (e.g., messages dedicated to rejecting the update or specifically carrying a direct code, domain, or value understood to be rejected). The messages of events 6B (1) -8 specifically indicate that the cell requested for the update belongs to a forbidden area (e.g., a forbidden location area or a forbidden cell). In response, as events 6B (1) -9, the user equipment Unit (UE) stores the cell causing the reject message on its forbidden area list 202 (see fig. 3). The user equipment Unit (UE) then attempts to select another cell and will eventually select another cell (e.g., one that is subscribed to the operator network or otherwise enters its idle mode).

[000100] FIG. 6B (2) shows a second alternative to the second mode of rejecting updates. For the case of FIG. 6B (2), events 6-1 and 6-2, and events 6B-3 through 6B-7, are substantially the same as shown in FIG. 6B (1). However, similar to fig. 6A (2), the second alternative of fig. 6B (2) differs in the way it communicates the rejection of the update to the user equipment Unit (UE). In particular, this second alternative of fig. 6B (2) may occur when a new message for rejecting an update is not available in the secondary (first) operator network or otherwise feasible. In the second alternative of fig. 6B (2), the rejection message of events 6B (2) -8 is an RRC release message. Upon receiving the RRC release message of event 6B (2) -8, the user equipment Unit (UE) enters idle mode and attempts (as event 6B (2) -9) location registration to the core network 16.

[00101] The core network 16, having the same information as in the PLMN/area table 110, will reject the attempted location registration of event 6B (2) -9, as indicated by the reject message of event 6B (2) -10. The messages of events 6B (2) -10 indicate: the reason for the rejection is a forbidden area (e.g., forbidden location area [ LA ]). Although not shown as such in fig. 6B (2) for simplicity, the location registration of event 6B (2) -9 and the rejection of event 6B (2) -10 are made by the base station serving the cell for which the update is sought. Upon receiving such rejection, the user equipment Unit (UE) updates its list of forbidden areas 202 (see fig. 3) as event 6B (2) -11. Finally, the user equipment Unit (UE) will select another area (e.g., desirably the area of the subscribed operator network) and perform a successful registration.

[000102] in the exemplary implementation of FIGS. 6B (1) and 6B (2), the message of event 5B-1 is a RELOCATION REQUERED message, and the message of event 5B-2 is a RELOCATION REQUEST message.

[000103] avoiding UE access to forbidden cells

000104 the third solution is that the UE has the function of avoiding the selection of a cell of a competing network in a competing area in either the cell _ FACH or cell _ PCH state, even if this network is "equivalent" from the cell selection point of view. The third solution part thus relates to the situation where the user equipment unit is subscribed to its home operator network (e.g. a subscribed (second) operator network) and is in connected mode, but attempts a cell reselection to a target cell called restricted cell.

000105 As shown in FIG. 3, according to the present invention, a user equipment Unit (UE) has a network access filtering function 200 that checks whether a target cell is a restricted cell or not. In an exemplary implementation, the mobile terminal maintains a list of restricted areas (e.g., forbidden area list 202) that is consulted as part of the check. The network access filtering function 200 may be implemented using individual hardware circuits, using software functioning in conjunction with a suitably programmed digital microprocessor or general purpose computer, using an Application Specific Integrated Circuit (ASIC), and/or using one or more Digital Signal Processors (DSPs).

[000106] thus, in this third resolution part, the network access filtering function 200 of the user equipment Unit (UE) verifies that: the target cell is not part of an area (e.g., location area [ LA ]) in the forbidden area list 202. In this check, the UE does not indicate any change of area (e.g., LA) to higher layer mobility management. The check of the area (e.g., LA) in connected mode is simply to determine whether it is allowed to access the cell.

[000107] in one implementation of the invention, the same list of forbidden areas for idle mode can be used for connected mode.

[000108] the list 202 of restricted areas may be updated after the location is registered with the core network, as in the manner shown in FIGS. 5A (2) and 6A (2). Alternatively, the list of restricted areas 202 may be updated upon receiving a rejection of the attempted cell update [ e.g., in the manner shown in fig. 5A (1) and 6A (1) ].

000109 figure 8 shows that a source Radio Network Controller (RNC) SRNC of an originating operator network optionally stores a copy 110' of a PLMN/area table 110 of a target RNC of a secondary operator network. Through the copy 110' of the table, the source RNC of the originating operator network can predict whether access will be denied. If by means of the copy 110' of the table the source RNC of the originating operator network predicts a rejection of an access, unnecessary signalling between the source SRNC and the target RNC can be avoided.

000110 the invention thus advantageously allows two operators, each having their own PLMN, to cooperate in the coverage of some parts of the licensed area, while they may compete in other parts. In particular, the present invention provides for avoiding and denying access by a user equipment Unit (UE) to cells for which the UE is not authorized to use resources.

000111 while the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A method for use in a radio access network of a first operator network having cells eligible for utilization of a user equipment unit in a connected mode and subscribed to a second operator network, the method comprising:

designating any cells in the first operator network for which the second operator network has competing cells as restricted cells;

obtaining an International Mobile Subscriber Identity (IMSI) of the user equipment unit and an identifier of a cell of the first operator network;

a table maintained by the first operator network is consulted to determine whether the cell of the first operator network is a restricted cell, and, if so,

the attempted utilization of the restricted cell by the user equipment unit subscribed to the second operator network is rejected.

2. The method of claim 1, wherein, for a user equipment unit subscribed to the second operator network, the rejecting step comprises rejecting one of: (1) handover to the restricted cell, and (2) cell/URA update by the user equipment unit via the restricted cell.

3. The method of claim 2, wherein the user equipment unit is in one of the following states: cell _ DCH state, cell _ FACH state, cell _ PCH state, and URA _ PCH state.

4. The method of claim 2, wherein when the second operator network attempts to perform a handover to a target cell of the first operator network for a user equipment unit subscribed to the second operator network, the method further comprises:

determining, at the first operator network, whether the target cell is a restricted cell; and if so, the processor is further configured to,

the handover is rejected.

5. The method of claim 4, further comprising:

obtaining an International Mobile Subscriber Identity (IMSI) of the user equipment unit and an identifier of a target cell from a source radio network controller of an originating operator network;

a determination is made at a controlling radio network controller of the first operator network whether the target cell is a restricted cell.

6. The method of claim 5, wherein the user equipment unit is in a cell _ DCH state, the method further comprising obtaining the international mobile subscriber identity, IMSI, of the user equipment unit and the identity of the target cell from a RL setup request message issued by a source radio network controller of the originating operator network.

7. The method of claim 5, wherein the step of determining at the controlling radio network controller of the first operator network whether the target cell is a restricted cell comprises:

obtaining a PLMN code from the IMSI of the user equipment unit;

a table maintained by the controlling radio network controller is consulted to determine whether the target cell is eligible for handover of the user equipment unit based on the acquired PLMN code.

8. The method of claim 2, wherein when the user equipment unit attempts to perform a cell/URA update associated with the target cell of the first operator network, the method further comprises:

the update is rejected.

9. The method of claim 8, further comprising:

10. The method of claim 9, wherein the user equipment unit is in one of a cell _ FACH state and a cell _ PCH state, and the method further comprises obtaining the international mobile subscriber identity, IMSI, of the user equipment unit and the identity of the target cell from a common transport channel resource request message issued by a source radio network controller of the originating operator network.

11. The method of claim 9, further comprising generating a message: it rejects the cell/URA update and informs that the cell is restricted.

12. The method of claim 1, wherein the attempted utilization of the restricted cell by the user equipment unit subscribed to the second operator network is an attempted cell reselection by the user equipment unit, and the method further comprises sending an identification of the restricted cell from the first operator network to the user equipment unit.

13. The method of claim 12, further comprising sending the identity of the restricted cell from the first operator network to the user equipment unit after the attempted location registration by the user equipment unit.

14. The method of claim 12, further comprising sending an identification of the restricted cell from the first operator network to the user equipment unit when the message rejecting the attempted cell update by the user equipment unit is sent to the user equipment unit.

15. A radio access network of a first operator network, the radio access network having cells which are eligible for utilization by a user equipment unit in a connected mode and subscribed to the second operator network; the radio access network includes:

means for designating any cells in the first operator network for which the second operator network has competing cells as restricted cells;

means for obtaining an international mobile subscriber identity, IMSI, of the user equipment unit and an identity of a cell of the first operator network;

means for consulting a table maintained by the first operator network to determine whether the cell of the first operator network is a restricted cell, and, if so,

means for rejecting attempted utilization of the restricted cell by a user equipment unit subscribed to the second operator network.

16. The radio access network of claim 15, wherein, for a user equipment unit subscribed to the second operator network, the means for rejecting rejects one of: (1) handover to a restricted cell, and (2) cell/URA update by the user equipment unit over the restricted cell.

17. The radio access network of claim 16, wherein the user equipment unit is in one of the following states: cell _ DCH state, cell _ FACH state, cell _ PCH state, and URA _ PCH state.

18. The radio access network of claim 16, wherein the initiating operator network attempts to perform a handover of a user equipment unit subscribed to the second operator network to a target cell of the first operator network, the radio access network further comprising:

means for obtaining an international mobile subscriber identity, IMSI, of a user equipment unit and an identity of a target cell from an originating operator network;

means for determining, at the first operator network, whether the target cell is a restricted cell using the IMSI; and if so, the processor is further configured to,

means for rejecting the handover.

19. The radio access network of claim 18, wherein the means for obtaining obtains the international mobile subscriber identity, IMSI, of the user equipment unit and the identity of the target cell from a source radio network controller of the originating operator network, and wherein the means for using the IMSI to determine whether the target cell is a restricted cell is located at a controlling radio network controller of the first operator network.

20. The radio access network of claim 19, wherein the user equipment unit is in a cell _ DCH state, and wherein the means for obtaining obtains the international mobile subscriber identity, IMSI, of the user equipment unit and the identity of the target cell from a RL setup request message issued by a source radio network controller of the originating operator network.

21. The radio access network of claim 19, wherein the means for using the IMSI to determine whether the target cell is a restricted cell comprises:

means for obtaining a PLMN code from the IMSI of the user equipment unit;

a table maintained by the controlling radio network controller, the table being consulted to determine whether the target cell is eligible for handover of the user equipment unit based on the acquired PLMN code.

22. The radio access network of claim 16, wherein the user equipment unit attempts to perform a cell/URA update for a target cell of the first operator network, and wherein the radio access network further comprises:

means for obtaining an international mobile subscriber identity, IMSI, of the user equipment unit and an identity of the target cell from the originating operator network;

means for determining, at a first operator network, whether a target cell is a restricted cell; and if so, the processor is further configured to,

means for providing a notification that the update was rejected.

23. The radio access network of claim 22, wherein the means for obtaining obtains the international mobile subscriber identity, IMSI, of the user equipment unit and the identity of the target cell from a source radio network controller of the second operator network; and wherein the means for determining is located at a controlling radio network controller of the first operator network.

24. The radio access network of claim 23, wherein the user equipment unit is in one of a cell _ FACH state and a cell _ PCH state, and wherein the means for obtaining obtains the international mobile subscriber identity, IMSI, of the user equipment unit and the identity of the target cell from a common transport channel resource request message sent by a source radio network controller of the second operator network.

25. The radio access network in claim 23, further comprising means for generating a message that rejects the update and informs the target cell that it is restricted.

26. The radio access network of claim 15, wherein the attempted utilization of the restricted cell by the user equipment unit subscribed to the second operator network is an attempted cell reselection by the user equipment unit, and the radio access network further comprises means for sending an identification of the restricted cell from the first operator network to the user equipment unit.

27. The radio access network of claim 26, wherein the means for transmitting the identification of the restricted cell from the first operator network to the user equipment unit is transmitted after an attempted location registration by the user equipment unit.

28. The radio access network of claim 26, wherein the means for transmitting the identification of the restricted cell from the first operator network to the user equipment unit transmits the identification of the restricted cell when a message rejecting an attempted cell update by the user equipment unit is transmitted to the user equipment unit.

29. A radio network controller of a radio access network of a first operator network, the radio access network having cells eligible for utilization of user equipment units in a connected mode and subscribed to a second operator network, the radio network controller comprising:

means for determining whether a cell of the first operator network is a restricted cell using the IMSI;

means for rejecting attempted utilization by a user equipment unit subscribed to the second operator network of a restricted cell of the first operator network, the restricted cell being one of the first operator network for which the second operator network has a competing cell.

30. The radio network controller of claim 29, wherein, for a user equipment unit subscribed to the originating operator network, the radio network controller rejects one of: (1) handover to restricted cell, and (2) cell/URA update by the user equipment unit via the restricted cell.

31. The radio network controller of claim 30 wherein the radio network controller rejects the attempted utilization when the user equipment unit is in one of: cell _ DCH state, cell _ FACH state, cell _ PCH state, and URA _ PCH state.

32. The radio network controller of claim 30, wherein, when the initiating operator network attempts to perform a handover to a target cell of the first operator network for a user equipment unit subscribed to the second operator network, the radio network controller:

obtaining an International Mobile Subscriber Identity (IMSI) of a user equipment unit and an identification of a target cell;

using the IMSI at the first operator network to determine whether the target cell is a restricted cell; and if so, the processor is further configured to,

notifying the originating operator network: the handover is rejected.

33. The radio network controller of claim 32, wherein the radio network controller obtains an international mobile subscriber identity, IMSI, of the user equipment unit and an identification of the target cell from a source radio network controller of the originating operator network, and wherein the radio network controller uses the IMSI to determine whether the target cell is a restricted cell and the radio network controller is a controlling radio network controller of the first operator network.

34. The radio network controller of claim 33 wherein the user equipment unit is in a cell _ DCH state, and wherein the radio network controller obtains the international mobile subscriber identity, IMSI, of the user equipment unit and the identification of the target cell from a RL setup request message issued by the source radio network controller of the originating operator network.

35. The radio network controller of claim 33 wherein the radio network controller obtains the PLMN code from an IMSI of the user equipment unit; and wherein the radio network controller has a table (110) which is consulted to determine whether the target cell is eligible for handover of the user equipment unit based on the acquired PLMN code.

36. The radio network controller of claim 30, wherein, when the user equipment unit attempts to perform a cell/URA update associated with the target cell of the first operator network, the radio network controller:

determining whether the target cell is a restricted cell; and if so, the processor is further configured to,

a notification is provided that the update is rejected.

37. The radio network controller of claim 36, wherein the radio network controller obtains the international mobile subscriber identity, IMSI, of the user equipment unit and the identity of the target cell from a source radio network controller of the originating operator network; and wherein the radio network controller is a controlling radio network controller of the first operator network.

38. The radio network controller of claim 37 wherein the user equipment unit is in one of a cell _ FACH state and a cell _ PCH state, and wherein the radio network controller obtains the international mobile subscriber identity, IMSI, of the user equipment unit and the identity of the target cell from a common transport channel resource request message issued by a source radio network controller of the originating operator network.

39. The radio network controller of claim 37 wherein the radio network controller generates a message denying the update and informing the target cell that it is restricted.

40. A mobile terminal that subscribes to a home operator network, the mobile terminal attempting to utilize a cell operated by a foreign operator network and competing with a cell operated by the home operator network in a connected mode, the mobile terminal:

a list of restricted areas is maintained,

the list of restricted areas is updated upon receipt of a reject message.

41. The mobile terminal of claim 40, wherein the mobile terminal is in one of the following states: cell _ DCH state, cell _ FACH state, cell _ PCH state, and URA _ PCH state.

42. The mobile terminal of claim 40, wherein the mobile terminal updates the list of restricted areas after location registration with the core network.

43. The mobile terminal of claim 40, wherein the mobile terminal updates the list of restricted areas upon receiving a rejection of the attempted cell/URA update.