Subscriber interrogation point - Patent Review 5210787

What is claimed is:

1. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber identified by a mobile identification number can be connected,

a plurality of mobile switching centers which serve as the home exchange for a plurality of mobile subscribers and store within a memory of each, preselected information associated with each mobile subscriber for which it is the home exchange;

a plurality of mobile switching centers which can serve as the visited exchange for a plurality of mobile subscribers for which each is not the home exchange thereof and store within the memory of each preselected information associated with each mobile subscriber within the network capable of roaming into said visited exchange;

a data network interconnecting each of said mobile switching centers for the communication of information therebetween; and

a subscriber interrogation point connected to the data network for communications therewith and being associated with either other subscriber interrogation points or a group of mobile subscribers the home exchanges of which are located in a particular geographic area, said subscriber interrogation point having a memory containing information associated with a mobile identification number corresponding to each mobile subscriber in said group identifying either the home exchange of that particular subscriber or other subscriber interrogation points able to identify such home exchange; and,

means for storing in the memory of each of said plurality of mobile switching centers which can serve as a visited exchange, information associated with the mobile identification number of each mobile subscriber in the network which identifies a subscriber interrogation point with which that mobile station is associated and not its home exchange so that when the home exchange of a mobile station is changed that information need only be modified in the memory of the mobile station's associated subscriber interrogation point and not in the memory of each visited exchange into which it can roam.

2. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber can be connected as set forth in claim 1 which also includes:

means, within each mobile switching center which can serve as a visited exchange and responsive to a request for registration by a visiting mobile subscriber, for sending a location update request message addressed to the subscriber interrogation point associated with the visiting mobile subscriber;

means, within each subscriber interrogation point and responsive to the receipt of a location update request message from a visited exchange, for retrieving from memory the address of the home exchange of the visiting mobile subscriber identified in said location update request message; and

means within each subscriber interrogation point for forwarding said location update request message to said address of the home exchange of said visiting mobile subscriber.

3. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber can be connected as set forth in claim 1 which also includes:

means, within each mobile switching center which can serve as a visited exchange and responsive to a request for registration by a visiting mobile subscriber, for sending a location update request message addressed to the subscriber interrogation point associated with the visiting mobile subscriber;

means, within each subscriber interrogation point and responsive to the receipt of a location update request message from a visited exchange, for retrieving from memory the address of another subscriber interrogation point which contains the address of the home exchange of the visiting mobile subscriber identified in said location update request message; and

means within each subscriber interrogation point for forwarding said location update request message to said address of the other subscriber interrogation point.

4. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber can be connected as set forth in claim 2 in which said forwarding means includes:

means for substituting the address of the home exchange of the visiting subscriber for the address of the subscriber interrogation point within the location update message request received by the subscriber interrogation point.

5. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber may be connected as set forth in claim 3 in which said forwarding means includes:

means for substituting the address of a subsequent subscriber interrogation point containing the address of the home exchange of the visiting mobile subscriber for the address of the subscriber interrogation point within the location update request message received by the subscriber interrogation point.

6. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber may be connected as set forth in claim 2 which:

said group of mobile subscribers associated with said subscriber interrogation point are divided into subgroups each of which is associated with an additional subscriber interrogation point which stores in memory the home exchange of its associated mobile subscribers; and

said subscriber interrogation point memory stores the address of the one of said additional subscriber interrogation points which is associated with each subscriber rather than the home exchange address thereof.

7. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber may be connected as set forth in claim 2 which also includes:

means within the home exchange of a visiting mobile subscriber and responsive to the receipt of a location update request message identifying one of its home subscribers for retrieving preselected information stored in memory related to said subscriber; and

means for communicating via said data network said preselected information to the visited exchange which sent the location update message request.

8. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber may be connected as set forth in claim 7 which also includes:

means within the home exchange of said visiting mobile for storing in memory the address of the visited exchange which sent the location update request message.

9. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber may be connected as set forth in claim 7 in which:

said preselected information retrieved from memory of said home exchange of said visiting mobile includes the service parameters of said mobile.

10. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber may be connected as set forth in claim 7 which also includes:

means within said visited exchange for storing in memory said preselected information received from the home exchange of said visiting mobile.

11. In a cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber can be connected as set forth in claim 2 which also includes:

means within the home exchange of a visiting mobile subscriber and responsive to the receipt of a location update request message which does not identify one of its home subscribers for communicating via said data network a not accepted message to the visited exchange which sent the location update message request.

12. A method of supplying information to a visited exchange within a mobile radio communications network associated with a mobile subscriber roaming within said network and which is identified by a mobile identification number, said method comprising the steps of:

storing within a home location associated with each mobile subscriber, data associated with the mobile identification number of each mobile subscriber and related to the service of said subscriber and the last known geographic location of said subscriber;

storing within a subscriber interrogation point, data related to the identity of the home location of a plurality of mobile subscribers;

storing within each exchange in said network, data which identifies a subscriber interrogation point associated with the mobile identification number of each mobile subscriber within said network and not an identification of the home exchange of said subscriber so that when the home exchange of a mobile subscriber is changed that information need only be modified in the memory of the mobile subscriber's associated subscriber interrogation point and not in the memory of each visited exchange into which it can roam;

sending, from a visited exchange in response to a registration request by a visiting mobile subscriber, a location update request message addressed to the subscriber interrogation point associated with the mobile identification number of said visiting mobile requesting registration;

forwarding said location update request message from said subscriber interrogation point to the home location associated with the visiting mobile subscriber requesting registration with the visited exchange.

13. A method of supplying information to a visited exchange within a mobile radio communications network associated with a mobile subscriber roaming within said network as set forth in claim 12, which also includes the step of:

sending, from a home location in response to the receipt of said location update request message from said visited exchange, a message to said visited exchange either accepting or rejecting said visiting mobile subscriber.

14. A method of supplying information to a visited exchange within a mobile radio communications network associated with a mobile subscriber roaming within said network as set forth in claim 13, which also includes the step of:

sending, along with an acceptance message to said visited exchange, data related to the service of said visiting subscriber; and

storing in the home location of the visiting subscriber the address of the visited exchange.

15. A method of supplying information to a visited exchange within a mobile radio communications network associated with a mobile subscriber roaming within said network as set forth in claim 12 in which said location update request message addressed to the subscriber interrogation point associated with said visiting mobile includes an origination point code, a destination point code and a message block and in which said step of forwarding said location update request message from said subscriber interrogation point to the home location comprises the steps of:

changing the destination point code of said location update request message from that of the subscriber interrogation point receiving the message to that of the home location associated with said visiting mobile; and

forwarding said location update request message from said subscriber interrogation point to said home location.

16. A method of supplying information to a visited exchange within a mobile radio communications network associated with a mobile subscriber roaming within said network as set forth in claim 15 in which the message block of said location update request message includes the address of said home exchange.

17. An improved cellular radio communications network of the type which includes a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber can be connected, a plurality of mobile switching centers which serve as the home exchange for a plurality of mobile subscribers and store within a memory of each preselected information associated with the mobile identification number of each mobile subscriber for which it is the home exchange, a plurality of mobile switching centers which can serve as the visited exchange for a plurality of mobile subscribers for which each is not the home exchange thereof and store within the memory of each preselected information associated with the mobile identification number of each mobile subscriber within the network capable of roaming into said visited exchange, and a data network interconnecting each of said mobile switching centers for the communications of information therebetween, said improvement comprising:

a subscriber interrogation point connected to the data network for communications therewith and being associated with a group of mobile subscribers the home of exchanges of which are located in a particular geographic area, said subscriber interrogation point having a memory containing information associated with the mobile identification number of each mobile subscriber in said group identifying either the home exchange of that particular subscriber or the identification of another subscriber interrogation point which contains such a home exchange identification; and

means for storing within the memory of each of said plurality of mobile switching centers which can serve as the visited exchange for a plurality of mobile subscribers for which each is not the home exchange thereof information associated with the mobile identification number of each mobile subscriber within the network capable of roaming into said visited exchange, said information identifying the subscriber interrogation point associated with said mobile subscriber and not the home exchange of said subscriber so that when the home exchange of a mobile subscriber is changed that information need only be modified in the memory of the mobile subscriber's associated subscriber interrogation point and not in the memory of each visited exchange into which it can roam.

18. An improved cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber can be connected as set forth in claim 17 which also includes:

means, within each subscriber interrogation point and responsive to the receipt of a location update request message from a visited exchange addressed to the subscriber interrogation point associated with a visiting mobile subscriber seeking registration within a visited exchange, for retrieving from memory the address of the home exchange of the visiting mobile subscriber identified in said update request message; and

means also within each subscriber interrogation point for forwarding said update request message to said address of the home exchange of said visiting mobile subscriber.

19. An improved cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber can be connected as set forth in claim 18 in which said forwarding means includes:

means for substituting the address of the home exchange of the visiting mobile subscriber for the address of the subscriber interrogation point within the update request message received by the subscriber interrogation point.

20. An improved cellular radio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber can be connected as set forth in claim 17 which also includes:

means, within each subscriber interrogation point and responsive to the receipt of a location update request message from a visited exchange addressed to the subscriber interrogation point associated with a visiting mobile subscriber seeking registration within a visted exchange, for retrieving from memory the address of another subscriber interrogation point containing the address of the home exchange of the visiting mobile subscriber identified in said update request message; and

means also within each subscriber interrogation point for forwarding said location update request message to said address of the other subscriber interrogation point.

21. An improved cellular ratio communications network including a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber may be connected as set forth in claim 20 in which said forwarding means includes:

means for substituting the address of the subsequent subscriber interrogation point containing the adresses of the home exchange of the visiting mobile subscriber for the address of the subscriber interrogation point within the location update request message received by the subscriber interrogation point.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to cellular mobile radio system networks and, more particularly, the routing of messages for roaming mobile subscribers within such networks.

2. History of the Prior Art

The public telecommunication systems can be divided generally into two components; the public switched telephone network (PSTN) and the mobile subscriber network. The latter category consists of very many mobile telephone subscribers ("Mobiles") who remain in communication with one another and with telephones connected to the PSTN by virtue of radio links within a plurality of adjacent cells. Each cell is illuminated by the radio transmissions from a particular base station which covers that cell and which is in turn coupled to a mobile switching center ("MSC") which controls the radio linkages between many different base stations and their associated cells covering a given geographic area. Each cellular exchange or cellular system is made up of one or more MSCs and its associated base stations serving the mobiles within a particular geographic area. Mobile telephone systems are connected to the PSTN to enable mobile subscribers and land base subscribers to freely communicate with one another and are interconnected with one another in different geographic areas to comprise a network.

Each mobile subscriber is associated with a particular home MSC or home location register which maintains a record of all relevant information associated with that mobile including the type of telephone service and options it has selected to receive. For example, a home MSC will store a mobile subscriber's mobile identification number ("MIN") along with its electronic serial number identifying the particular mobile instrument; the categories of service for which it is contracted, e.g., whether it has call forwarding or call waiting or whether it may originate long distance calls to certain specific areas or not; and other subscriber specific information. When the mobile subscriber is operating within its own geographic area and calls to and from the mobile are being handled through the mobile's home MSC all of this information is readily available and used by the MSC in handling telephone traffic with the mobile. Another item of information stored in the home MSC in the mobile's record is the last known geographic location of the mobile. This information enables the home MSC to locate the mobile whenever it receives a call directed to the telephone number in the home MSC assigned to the mobile.

Each mobile within the network maintains contact with the radio communication system by means of a process known as registration. In the process of registration, each mobile periodically receives a signal from a base station including data which identifies the particular system with which the mobile is in radio contact, referred to as a system identification number ("SID") in North American cellular systems. The mobile in turn responds to the periodic signals from the system base station contained within an overhead message train, including the SID signal, by sending to the system its MIN and its electronic serial number for registration with it as a user. There are basically three ways in which a mobile may register: autonomous registration (in response to the mobile entering a new geographic area), periodic registration (in response to the passage of time since the last registration), and registration while originating a call from the mobile (in response to an unregistered mobile seeking to originate a call).

When a mobile travels from the geographic area covered by its home MSC, it is said to be "roaming." In such a situation, it is desirable to be able to still provide telephone service to the mobile both in response to the mobile originating a call to be connected either to another mobile in the network or to a subscriber on the PSTN or to a call being directed from another subscriber to the mobile. Thus, it is necessary to have a way in which the mobile can be tracked to any exchange within which it may be located in the network, known as a visited exchange, outside of its home exchange. This is done by a process of maintaining records within each exchange as to the identity of all roaming mobiles currently operating within that exchange as well as the current location of all mobiles for whom that exchange is the home exchange. These data are regularly communicated between the various MSCs comprising the cellular mobile system network. This information enables the providing of telephone service to a roaming mobile by assuring the visited exchange that the mobile is authorized to be making and receiving calls in the visited exchange and that it is financially responsible for those calls. This information also provides the home exchange with data on where the mobile is currently located so that calls may be delivered from outside of the visited exchange to the mobile within that exchange.

Prior art systems provide arrangements whereby each exchange stores enough of the MIN to identify the home exchange for each mobile within the entire network which might seek to register as a roaming visitor within that exchange. Each visited exchange will, upon registration by a roaming mobile within that exchange, consult information stored within its memory, known as a digit analysis table, to determine the home exchange of the mobile in order to be able to contact that home exchange to authenticate the mobile and to request data relating to the service parameters of the mobile. Thus, each MSC within the entire network of MSCs must maintain a detailed record related to all mobiles within the network enabling that MSC to locate the home exchange of every mobile operating within the network should that mobile register as a visitor within that exchange. While such a system enables the handling of calls and the providing of service to roaming mobile subscribers, it requires the frequent updating of mobile subscriber information within a large number of MSCs as that information changes. For example, in large metropolitan areas, such as Los Angeles, in which there are a large number of different MSCs serving as home exchanges to subscribers, there are frequent revisions and changes to the service areas of each MSC because of growth in the number of subscribers and the need to reassign certain subscribers to new MSCs as the efficient capacity of particular MSCs is reached. Thus, each time the subscription for a particular mobile is moved from one MSC to another, that changes its home MSC and requires that same information to be sent to every other MSC in the network as to the new home MSC of the mobile. It is a huge undertaking to regularly update and change the memory contents of every MSC in the network every time it is necessary to update the digit analysis table of that MSC in order to render it capable of handling registrations from a mobile the home exchange of which has been changed.

The system of the present invention provides an additional node within the mobile exchange network to facilitate the handling of call registration data within the network. The provision of subscriber interrogation points within a cellular mobile telecommunications exchange network in accordance with the system of the present invention greatly simplifies the maintenance of subscriber information within the network.

SUMMARY OF THE INVENTION

In one aspect the system of the present invention includes a cellular radio communications network having a plurality of mobile switching centers each having a plurality of base stations with which a mobile subscriber may be connected. A plurality of mobile switching centers serve as the home exchange for a plurality of mobile subscribers and store within the memory of each preselected information associated with each mobile subscriber for which it is the home exchange. A plurality of mobile switching centers serve as the visited exchange for a plurality of mobile subscribers for which each is not the home exchange and store within the memory of each preselected information associated with each mobile subscriber within the network capable of roaming into said visited exchange. A data network interconnects each of the mobile switching centers for the communications of information between them. A subscriber interrogation point is connected to the data network for communications with it and is associated with either other subscriber interrogation points or a group of mobile subscribers the home exchanges of which are located in a particular geographic area. The subscriber interrogation point has a memory containing information associated with each mobile subscriber identifying either the home exchange of that particular subscriber or other subscriber interrogation points able to identify such home exchange.

In another aspect the invention includes a method of supplying information to a visited exchange within a mobile radio communications network associated with a mobile subscriber roaming within the network. Data related to the service of each mobile subscriber and the last known geographic location of the subscriber is stored in memory in a home location associated with each mobile subscriber. Data related to the home location of a plurality of mobile subscribers is stored within a subscriber interrogation point. Data which identifies a subscriber interrogation point associated with each mobile subscriber within the network is stored within each exchange in the network. A location update request message addressed to the subscriber interrogation point associated with said visiting mobile is sent from a visited exchange in response to either a registration request or call initiation by a visiting mobile subscriber. A location update request message is forwarded from the subscriber interrogation point to the home location associated with the visiting mobile subscriber requesting registration with the visited exchange. Thereafter, the home exchange communicates directly with the visited exchange by means of the data network.

BRIEF DESCRIPTION OF THE DRAWINGS

For an understanding of the present invention and for further objects and advantages thereof, reference may be had to the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a block diagram of an interconnection between a home and a visited exchange including a subscriber interrogation point provided in accordance with the present invention;

FIG. 2 is a block diagram of an illustrative arrangement of subscriber interrogation points within a cellular mobile exchange network in accordance with the system of the present invention;

FIG. 3 is a chart illustrating storage of various items of information within the system of the present invention;

FIG. 4 is a chart illustrating an exemplary flow of messages within the system of the present invention;

FIG. 5A is a flow diagram illustrating the handling of information by a visited exchange for a visiting mobile seeking to register in that exchange in accordance with the system of the present invention;

FIG. 5B is a flow diagram illustrating the handling of information within a subscriber interrogation point in accordance with the system of the present invention; and

FIG. 5C is a flow diagram illustrating the handling of information within a home exchange in response to an authentication request from a visited exchange in accordance with the system of the present invention.

DETAILED DESCRIPTION

As discussed above, in the prior art mobile telephone communication network each MSC is required to maintain within its digit analysis table information with regard to the home exchange of each mobile operating within the network and which could potentially be a visitor within that exchange. This requires frequent updating of every MSC in the entire network whenever the home exchange of any one mobile is changed, for example, due to reassignment of the subscription of that mobile to a new MSC due to the adding of switches within a metropolitan area or to the relocation of that mobile due to change in service loction. It should be understood that the term "home exchange" of a mobile includes not only the home MSC of that mobile, but also a home location register ("HLR") which may be either included as part of the home MSC or a regional register containing the subscriber identification information for one or more MSCs. Nevertheless, the maintenance of information related to the home exchange of a large number of mobiles can be a substantial, time consuming and expensive proposition.

The system of the present invention includes providing one additional level of analysis within the mobile communications network which has been termed, for purposes of explanation, a subscriber interrogation point ("SIP"). As shown in FIG. 1, a visited MSC 10 of a mobile is connected to the home system 11 of that mobile through the data communication network 12. Also connected into the data communication network 12 is a subscriber interrogation point 13 which is associated with the home exchange 10. Any request for information with regard to a roaming mobile seeking to register within the visited MSC 10 is routed directly to the subscriber interrogation point 13 which stores information relating to the home exchange of all of the mobiles within the network. The subscriber interrogation poont 13 simply provides the address of the home exchange to the update request sent by the visited exchange to the subscriber interrogation point and forwards it on to the home exchange 11. Thereafter, the home exchange 11 communicates directly with the visited exchange 10 via the data communications network 12 and the subscriber interrogation point 13 does not form part of the communication loop therebetween. Thus, the subscriber interrogation point 13 is provided simply to route roaming mobile information to the appropriate home exchange and to greatly simplify the updating of information as to the home exchange of every mobile within the system. Updating information for each mobile within the network need only be provided to the subscriber interrogation point 13 associated with the home exchange of that mobile rather than to each and every MSC within the network. As will be further seen, the subscriber interrogation point 13 may even provide the address of a more specific subscriber interrogation point within the network which will, in turn, provide the specific address of the home exchange.

Referring next to FIG. 2, there is shown a block diagram of a mobile cellular communications system network constructed in accordance with the teachings of the present invention. A plurality of regional cellular mobile systems 21-24, each of which comprise a plurality of MSCs 25 which are all connected to a regional subscriber interrogation point 26-29. For example, the regional system 21 includes MSCs A-1 through A-5 and may illustratively represent a portion of the Los Angeles cellular system, while the regional grouping 22, comprising MSCs B-1 through B-5 may illustratively represent a portion of the New York metropolitan cellular system. Similarly, the grouping 23 of MSCs, comprising MSCs D-1 through D-4 could illustratively represent a portion of the exchanges within the Toronto, Canada metropolitan region, while the geographic grouping 24, including MSCs E-1 through E-4, might illustratively represent the Montreal metropolitan region.

The regional grouping of MSCs A-1 through A-5 are each connected to a subscriber interrogation point 26 (SIP A) and are each also connected, along with the subscriber interrogation point A, to a data communication network 31. Similarly, the regional area 22, comprising MSCs B-1 through B-5 are each connected to a subscriber interrogation point 27 (SIP B) and are each connected, along with SIP B, to the data communication network 31. The regional grouping of MSCs 23, including MSC D-1 through D-4 are each connected to the data communication network 31 along with their associated regional subscriber interrogation point 28 (SIP D) and the regional grouping of MSCs E-1 through E-4 are each also connected to the data communication network 31 along with their associated regional subscriber interrogation point 29 (SIP E). The super-regional subscriber interrogation point 30 (SIP C) is associated with both regional MSCs 23 and 24 is also connected to the data communication network 31.

As discussed above, when a mobile 32 seeks to register as a visitor in exchange MSC A-1, that MSC will analyze the MIN of that mobile to determine two things:

(a) whether the subscriber is currently connected; and

(b) the identity of the subscriber's home exchange. Visited exchange A-1 does this by going to its digit analysis table to find the home exchange of the mobile in order to perform three actions:

(a) update the geographic location of the mobile stored within its home exchange;

(b) authenticate the mobile as being capable of receiving service from the visited exchange; and

(c) obtain information as to the detail service specifications which the visiting mobile subscriber is to receive.

When the mobile 32, the home exchange of which is assumed to be B-1, first seeks to register as a visitor within the exchange area 21 by sending a registration or call origination message to MSC A-1, MSC A-1 sends a validation/authentication location update request to the regional subscriber interrogation point SIP B associated with the home exchange of the mobile 32 via the data communication network 31. The subscriber interrogation point SIP B accesses the data stored within its memory to obtain from the MIN of the mobile requesting registration the home exchange of that mobile and then reroutes the update location request back onto the data communication network 31 but readdressed to the home exchange of the mobile. Thereafter, information is returned to the visited exch