MXPA00002403A - Limiting access to private networks in cellular communications systems - Google Patents

Abstract

A mobile cellular communications system and method are disclosed, which limit access to private network cells (114) only to mobile terminals that are used by subscribers to those private networks. In cells belonging to the public network, only information about the public cells (122) is broadcast on the public system information control channels. This public cell (122) information is thus the only cell information that the non-subscribers'mobile terminals are able to receive. When a mobile terminal belonging to a subscriber of one or more private networks surfaces in a public cell (122), the public network transmits a radio link control message to that mobile terminal, which contains information about the candidate cells for selection associated with the private network(s) involved. The private network transmits system information via the private cell (114) to a subscribing mobile terminal about the private and public cells'neighboring cells (122). Consequently, the subscribing mobile terminal will regard the public network cells (122) and private network cells (114) as integral parts of the overall cellular system. Cells associated with private networks to which that mobile terminal's end user is a"non-subscriber"are thus"invisible"to that mobile terminal.

Description

LIMITING ACCESS TO PRIVATE NETWORKS IN CELLULAR COMMUNICATIONS SYSTEMS BACKGROUND OF THE INVENTION Technical Field of the Invention The present invention relates generally to the field of mobile communications and in particular to a method for limiting access to private cellular networks. Description of the Related Art In today's highly advanced cellular radio communications systems, there is a growing need for network operators that can differentiate between numerous sets of different end users. Consequently, in order to meet this growing need, operators deploy a multitude of relatively small closed and / or private cellular sub-networks within the larger public cellular networks. As such, the use of these private subnets allows public network operators to guarantee selected sets of end users a specified quality of service. Similarly, only specific end users are granted access to cells that belong to closed subnets. For example, an indoor radio network that covers the offices of a particular business can be operated as a private or closed sub-network within a public cellular network.

Consequently, only employees of that business will be allowed access to and use that indoor radio network. Of crucial importance to the success of these new private and closed networks, is that they can be easily integrated with public cellular networks. In particular, from the point of view of a private network subscriber, the total system must appear to allow transfers without splices or unions between public and private network cells. In addition, it is also important to ensure that cellular users, who are not subscribers to a private network (hereinafter "non-subscribers"), are not granted access (or even have perception or knowledge of) to the cells of private networks. Figure 1 is a diagram showing an exemplary mobile communications system, providing radio coverage for mobile terminals (not explicitly shown) with a plurality of private network cells operating within an area covered by one or more macrocells of a public cellular network. Next, for clarity, consider that a mobile end user can be a subscriber for a public and private network, but a "non-subscriber" is a mobile end user who does not subscribe to the private networks involved. Alternatively, a "subscriber" is a mobile end user who subscribes to the private network (s) involved. In current operation, the public cellular network may comprise a plurality of macro cells, micro cells and / or pico cells. Specifically, for the exemplary mobile communications system shown in Figure 1, in order for a mobile terminal of a user to move from a public macro cell 12 to any of the private network cells 14, 16, 18, 20, or from the macrocell 22 to the private network cell 20, there must be a neighbor cell relationship defined between the macrocell (12 or 22) and the respective private network cell (14, 16, 18 or 20). In addition, in order for a mobile terminal to move from a macrocell to a private network cell, the mobile terminal must be able to "see" a private cell as a candidate for cell selection, and also be able to measure the signal strength of the base station transmitter that defines that private cell. In certain mobile communication systems, such as for example the general packet radio service (GPRS = General Packet Radio Service) of the global digital cellular system for mobile communications (GSM = Global System for Mobile Communications), mobile terminals are responsible for cell selection Consequently, these mobile terminals must have access to all system parameters regarding what criteria to use to select a private cell while it is located in a public macro cell. As such, in this system that uses a hierarchical cell structure (HCS = Hierarchical Cell Structure) with numerous private networks, there are large numbers of macro neighbors that create the following problems. First, in these conventional mobile communication systems such as the GPRS, each corresponding set of cell selection parameters has to be broadcast in the control channel in the public macro cell, which imposes an unnecessarily large load on that channel. control. For example, in GPRS, this unnecessarily large load is imposed on the packet broadcast control channel (PBCCH = Packet Broadcast Control Channel). As detailed in the technical specifications of GSM 03.64 and 05.08, there are 15 selection parameters associated with each neighborhood cell, corresponding to approximately 70 bits of information. Consequently, since a load of approximately 700 bits of information is a maximum acceptable load for the PBCCH, it is evident that this system that operates with more than 10 neighboring cells will impose an unacceptable burden on the PBCCH. Second, to be able to test all the needs of end users of the conventional system, all available frequencies are broadcast on the broadcast control channel (BCCH). Consequently, for purposes of cell selection, end-user terminals are required to make downlink signal strength measurements at all those frequencies including even those frequencies that correspond to cells of private networks that some user terminals (not subscribers) are unable to access. These unnecessary downlink signal strength measurements for non-subscriber terminals produce significantly lower accuracies for measurements made on the other accessible cells. Third, in these mobile communication systems such as GPRS, there is currently no means to communicate to any mobile terminal just which cells are accessible (public) and which are not (private). Consequently, even if the previously described problems were to be solved, existing systems do not provide means to implement those solutions. Another related problem that is found in conventional mobile communication systems is that private networks become inaccessible to non-subscribing end users of the public, basically in two ways. Either the private network is completely isolated from the public network, or the cells in the private network become part of the public network but mark, for example, a "cell prohibited for public subscribers" flag, in the system information of diffusion given with respect to those private cells. Obviously, a significant problem with total isolation of the private network from the public network is that transfers can not be made from a cell in the private network to a cell in the public network or vice versa. Also, a significant problem in using the "banned cell" flag method is that all mobile terminals involved can "see" all available cells, including those cells that are inaccessible. In conventional mobile communication systems, the above-described problems lead to unnecessary use of processing resources, less time available for mobiles to perform downlink measurements on cell candidates for actual transfer and / or unacceptably large loads imposed on the channels of control of the public network. However, as described below, these problems are successfully solved by the present invention. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a mobile cellular communication system and a method by which private network cells can be kept hidden from non-subscribing mobile terminals.

It is another object of the present invention to provide a mobile cellular communication system and method, by which mobile non-subscriber terminals are not required to waste processing and time resources by making downlink signal strength measurements for private network base stations inaccessible. Still another object of the present invention is to provide a system and method of mobile cellular communications by which the downlink signal strength measurement accuracy for the public network can be significantly increased. It is also another object of the present invention to provide a system and method of mobile cellular communications by which a non-subscribing mobile terminal is unable to re-select cells associated with selected private networks. A further objective of the present invention is to provide a system and method of mobile cellular communications by which the transmission of private network information does not impose an unnecessary burden on control channels of a public system. Still another objective of the present invention is to provide a system and method of mobile cellular communications by which a mobile subscriber terminal can consider a private network as a fully integrated part of the public system, in order to be able to fully utilize features such as transfers between cells, or HCS features to assign priorities to the use of cells. In accordance with the present invention, the above and other objects are achieved by a mobile cellular communications system and method that limit access to private network cells only to mobile subscriber terminals. In cells that belong to the public network, only public cell information is disseminated in the information control channels of the public system. This public cell information, in this way is the only cell information that a non-subscribing mobile terminal can receive. When a mobile terminal belonging to a subscriber of one or more private networks arises to the surface in a public cell, the public network transmits a control message of radio link to the mobile terminal, which contains information regarding the candidate cells for selection. associated with the private network (s) involved. Private networks transmit system information by private cells to mobile subscriber terminals with respect to cells neighboring public and private cells. Consequently, mobile subscription terminals can consider the cells of public networks and the cells of private networks as integral parts of the total system. Cells associated with private networks to which the end user of the mobile terminal is a non-subscriber, in this way they are "invisible" to that mobile terminal. BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the method and apparatus of the present invention can be achieved by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: Figure 1 is a diagram showing a system exemplary mobile communications that provides radio coverage for mobile terminals with a plurality of private network cells operating within an area covered by one or more macro cells of a public cellular network; Figure 2 is a block diagram of an exemplary cellular communication system, which may be employed to implement a method of the present invention; and Figures 3A-3C are diagrams illustrating that "sees" a mobile subscription terminal in a geographic area covered by a plurality of cells of public and private networks defined by radio transceivers shown in Figure 2, in a communications system that is implemented in accordance with the preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE DRAWINGS The preferred embodiment of the present invention and its advantages are best understood by reference to Figures 1-3C of the drawings, in which like numbers are used for similar and corresponding parts of the various drawings. Essentially, in cells belonging to the public network, only the public cell information is broadcast in the public system information channel (for example PBCCH for GPRS). This is the only information that non-subscriber mobile terminals can receive from private networks. Consequently, from the point of view of these non-subscriber terminals, it appears that the private cells do not exist. However, when a mobile subscription terminal comes to the surface in a public cell, it transmits identification information to the public network. The public network accesses a database (for example a home location or service area register) and determines that the end user of the mobile terminal is a subscriber to one or more private networks. The public network sends a control message to that mobile terminal containing candidate information for cell selection with respect to the one or more cells of private networks.

That mobile terminal can then consider both private and public cells for cell re-selection. Specifically, Figure 2 is a block diagram of an exemplary cellular communications system that can be employed to implement a method of the present invention. For the preferred embodiment, the cellular communication system shown in Figure 2 can operate in accordance with the GPRS radio interface protocol (for example the GSM 04.60 technical specification published by the European Telecommunications Standards Institute). Institute) With reference to Figure 2, the public network (GPRS) 100 includes a service support node / mobile services switching center (MSC / SGSN) 102, which controls calls to and from other data communication systems and telephony (eg, public switched telephone network or PSTN, integrated digital service network or ISDN, public land mobile network or PLMN, public data networks or PDN, or even private networks.) Network 100 also includes at least one station controller base (BSC) 104 or 106, which is serviced by the MSC / SGSN 102. The BSC 104 controls a plurality of base transceiver stations (BTSs) 108a-108e and the functions ta them as transfers and channel assignments. Each BTS 108a-108e operates on a set of radio channels and defines a public macrocell. Each of a plurality of radio private network transceivers 109a-109d operate on their respective radio channels and define a private network cell (e.g., a plurality of micro- and / or-pico-cells). The plurality of private radio network transceivers 109a-109d can be controlled by one or more BSCs (e.g. 104 and / or 106). And a plurality of cells of public and private networks, which are defined by the public and private transceivers shown in Figure 2, are illustrated in Figures 3A-3C. Figures 3A-3C are diagrams illustrating what a mobile subscriber terminal "sees" in geographic areas covered by the plurality of cells of public and private networks defined by the radio transceivers shown in Figure 2, in a mobile communication system , which is implemented in accordance with the preferred embodiment of the present invention. For this exemplary embodiment, the public network 100 shown is a GPRS network. The public network 100 includes a plurality of macro public cells (for example at least neighborhood cells 112 and 122) each of which is defined by one of the BTSs 108a-108e shown in Figure 2. Figures 3A-3C also show a plurality of cells of private networks 114, 116 and 120, each of which is defined by a respective one of the private radio network transceivers 109a, 109b, 109c or 109d. Private network cells 114, 116 and 120 may be microcells, pico cells or cells in an HCS that include any appropriate private network cell structure. Figure 3A is a diagram illustrating what "sees" a mobile terminal when it is used by a subscriber of a private network, including a transceiver 109a, which defines cell 120 to cover the facilities of company I. Notably, as illustrated in this example, the mobile terminal of the subscriber can communicate with BSC 104 and MSC / SGSN 102 through the radio interfaces of the public cells (for example 112, 122) and the private cell 120. Since in this example, the user of the particular mobile terminal does not subscribe to any other of the private networks, only the private network associated with the cell 120 can communicate with or "be seen" by that mobile terminal of the subscriber. Consequently, for example if that mobile subscriber terminal is located in and actively communicates with MSC / SGSN 102 by, public cell 122, then the mobile subscriber terminal will be able to consider both public cell 112 and private cell 120 for -cell selection in case it passes to the coverage area of one of those cells. For this embodiment, a method for limiting access to private networks for private network subscribers can be implemented in part by preventing the broadcasting of any private network information over the public network information channel (PBCCH for the GPRS). However, when a mobile terminal is used by a subscriber of a private network it surfaces in a public cell (for example the mobile transmits a conventional cell update request message, or uplink initiation transfer message in the public cell 112 or 122), the public network (for example the GPRS network) 100 transmits a radio link control message for that mobile terminal, preferably on the associated packet control channel (PACCH). That transmitted radio link control message is preferably a signaling block message containing information regarding the candidate cells for cell selection associated with the private network involved. For the private network cell 120, the radio link control message transmitted to that mobile terminal may include selection candidate information with respect to the public cells 112 and 122. For example, in a GPRS system, such a control message of radio link may contain cell selection information for private cell 120. This information may include, but not be limited to, information regarding cell identity (eg, base station identity code or BSIC = Base Station Identity Code), priority class, temporary displacements to be used, permanent displacements to be used, signal intensity thresholds and more, as determined in the GSM 03.64 technical specification. The mobile terminal stores this cell selection candidate information in an internal memory storage site for as long as the mobile terminal in that public cell remains. Accordingly, the private network cell 120 appears to that mobile subscription terminal as an integral part of the public cellular radio network (e.g., the GPRS network) 100. As such, the mobile terminal of the subscriber may consider public cells 112 and 122 and the private cell 120 for cell re-selection for as long as it remains in the original public cell (112 or 120). The private network broadcasts (preferably over the broadcast control channel, BCH = Broadcast Control Channel) in its cells (eg, cells 120a and 120b) relevant system information with respect to the neighboring cells of public and private networks. This action is to ensure that whenever the mobile terminal is located in the coverage area of the appropriate public or private cells, will continue to consider the public cells and the private (subscribed) cell as an integral part of the total network. Cells associated with the private networks to which that end user of the mobile terminal does not subscribe (for example, cells 114 and 116 in Figure 3B described below) in this manner are "invisible" to that mobile terminal. Figure 3B is a diagram illustrating another view of what the mobile terminal "sees" when it is used by a subscriber of a private network with transceivers 109b and 109c, which define respective private cells 114 and 116, to cover two different facilities of the company II. As illustrated in Figure 3B, the mobile terminal of the subscriber can communicate with BSC 104 and MSC / SGSN 102 through the radio interfaces of public cell 112 and private cells 114 and 116. In this example, the method for limiting access The private networks are again partially implemented by preventing the broadcasting of any private network information over the public network information channel (eg PBCCH for GPRS). However, when a mobile terminal that is used by a subscriber of the private networks covering the facilities of the company II surfaces in the public cell 112 (for example, it transmits a cell update request message or a transfer message) uplink start in public cell 112), public network 100 transmits a radio link control block for that mobile terminal, preferably over PACCH. This transmitted signaling block message contains information regarding the candidate cells for cell selection associated with the private network involved. For private network cells 114 and 116, the radio link control message transmitted to that mobile subscriber terminal may include selection candidate information with respect to public cell 112. The mobile terminal stores this cell selection candidate information in an internal memory storage location for as long as it remains in that public cell. Accordingly, the private network cells 114 and 116 appear to that mobile subscription terminal as an integral part of the public cellular radio network (eg, GPRS network) 100. As such, that mobile terminal may consider the public cell 112 and the private cells 114 and 116 for cell re-selection for as long as it remains in public cell 112. The private network broadcasts (preferably over BCH) in cells 114 and 116, system information with respect to the neighboring cells of the networks public and private. The mobile terminal will thus consider the public cell and the private cells (subscribed) as part of the total network. Cells associated with the private networks to which the user of the mobile terminal does not subscribe (for example cell 120 in Figure 3A described above) in this way are "invisible" to that mobile terminal. Figure 3C is a diagram illustrating another view of what the mobile terminal "sees" when it is used by a subscriber to only the public network 100. As shown, since the current method of limiting access to private networks is implemented in part by not broadcasting any private network information over the public network information channel, that mobile terminal (a non-subscriber with respect to private networks) nor is it able to "see" or communicate through any of the private network cells ( for example cell 114, 116 or 120 in Figures 3A and 3B). However, this mobile terminal can still communicate with the public network 100 by means of macro public cells (for example, cell 112 or 122). By implementing the inventive concept of limiting access to subscribers of private radio networks in other cellular systems, such as for example GSM, the method described above with respect to Figures 2 and 3 can also apply to mobile terminals operating in the mode active. For example, a mobile terminal belonging to a subscriber of a private network located in the coverage area of a public GSM network, receives information regarding the private cells over the dedicated control channels (DCCH) of the GSM network, such as the channel autonomous control system (SDCCH Stand-alone Dedicated Control Channel), the associated slow control channel (SACCH = Slow Associated Control Channel) or the fast associated control channel (FACCH = Fast Associated Control Channel). The private network transceivers broadcast system information regarding candidate private cells and public cells to the mobile subscription terminal through the private cell. In addition, although the present method for limiting access to subscribers of private networks has been described above with respect to operating in exemplary GPRS or GSM public network environments, the invention is not intended to be so limited and may also be implemented with respect to any radio system appropriate cellular, such as for example the advanced mobile phone system (AMPS = Advanced Mobile Phone System), the advanced digital mobile phone system (D-AMPS = Digital Advanced Mobile Phone System), cellular systems operating under the IS- protocol 95 protocol, the pacific digital cellular system (PDC = Pacific Digital Cellular), etc.

Although a preferred embodiment of the method and apparatus of the present invention has been illustrated, in the accompanying drawings and presented in the above detailed description it will be understood that the invention is not limited to the described modes, but is capable of numerous rearrangements, modifications and subscriptions, without departing from the spirit of the invention, as established and defined in the following claims.

Claims (25)

1. - A method for limiting access to a private network coupled to a public cellular network, characterized in that it comprises the steps of: transmitting public cell information regarding the public cellular network in a public system information channel, the public cell information excludes private network cell information; in response to a signal received from a mobile subscription terminal, the public cellular network transmits a message from the mobile subscription terminal, the message includes cell selection candidate information for at least one cell associated with the private network; and the private network transmits neighbor cell information to the mobile subscription terminal by means of at least one cell associated with the private network.

2. - The method according to claim 1, wherein the public system information channel comprises a broadcast control channel.

3. - The method according to claim 1, wherein the public system information channel comprises a packet broadcast control channel.

4. The method according to claim 1, characterized in that the public system information channel comprises a dedicated control channel.

5. - The method according to claim 1, characterized in that the public system information channel comprises an associated control channel.

6. - The method according to claim 1, wherein the signal received from a mobile subscription terminal comprises a cell update message.

7. - The method according to claim 1, wherein the signal received from a mobile subscription terminal comprises a cell transfer initiation message.

8. - The method according to claim 1, characterized in that the cell at least associated with the private network comprises a microcell.

9. - The method according to claim 1, characterized in that the cell at least associated with the private network comprises a pico-cell.

10. The method according to claim 1, characterized in that it comprises the steps of: the mobile subscriber terminal receives the message including the cell selection candidate information and the neighbor cell information, and select at least one cell for communications from candidate cell selection information or neighborhood cell information.

11. A system for limiting access to a private network coupled to a public cellular communications network, characterized in that it comprises: first transmission means for sending public cell information regarding the public cellular communications network in a system information channel public, public cell information excludes private network cell information; reception means for a signal from a mobile subscription terminal; second transmission means in response to the signal from the mobile subscription terminal, for transmitting a message to the mobile subscription terminal, the message includes cell selection candidate information for at least one cell associated with the private network; and third transmission means coupled to the private network, to transmit neighbor cell information to the mobile subscription terminal by means of at least one cell associated with the private network.

12. - The system according to claim 11, characterized by the public system information channel comprises a broadcast control channel.

13. - The system according to claim 11, characterized in that the public system information channel comprises a packet broadcast control channel.

14. - The system according to claim 11, wherein the public system information channel comprises a dedicated control channel.

15. - The system according to claim 11, characterized in that the public system information channel comprises an associated control channel.

16. The system according to claim 11, characterized in that the signal from a mobile subscription terminal comprises a cell update message.

17. The system according to claim 11, characterized in that the signal from a mobile subscription terminal comprises a cell transfer initiation message.

18. - The system according to claim 11, characterized in that the cell at least associated with the private network comprises a microcell.

19. - The system according to claim 11, characterized in that the cell at least associated with the private network comprises a pico-cell.

20. The system according to claim 11, characterized in that the public cellular communications network comprises a GPRS network.

21. The system according to claim 11, characterized in that the public cellular communications network comprises a GSM network.

22. The system according to claim 11, characterized in that the public cellular communications network comprises an AMPS network.

23. - The system according to claim 11, characterized in that the public cellular communications network comprises a D-AMPS network.

24. The system according to claim 11, characterized in that the public cellular communications network comprises an IS-95 network.

25. The system according to claim 11, characterized in that the public cellular communications network comprises a cellular network based on satellite. SUMMARY OF THE INVENTION A mobile cellular communication system and method with limited access to private networks (114) is described only to the mobile terminals that are used by the subscribers to those private networks. In cells belonging to the public network, only information regarding the public cells (122) is disseminated in the public system information control channels. This public cell information (122) in this way is the only cell information that non-subscribing mobile terminals are capable of receiving. When a mobile terminal belonging to a subscriber of one or more private networks surfaces in a public cell (122) the public network transmits a radio link control message to that mobile terminal, which contains information regarding the candidate cells for selection associated with the private network (s) involved. The private network transmits system information through the private cell (114) to a mobile subscription terminal with respect to the private and public cells of the neighbor cells (122). Accordingly, the mobile subscription terminal will consider the public network cells (122) and the private network cells (114) as integral parts of the total cellular system. Cells associated with private networks to which that end user of the mobile terminal is "non-subscriber" in this way are "invisible" to that mobile terminal. -020