MXPA99000960A - Method for allocating a mobile station tmsi - Google Patents

Abstract

A portion of the bits within an assigned Temporary Mobile Station Identification (TMSI) number are encoded based upon a subscriber's group classifications (i.e., classifications based on the user's characteristics, such as subscriber services and affiliation). When a mobile station user requests service in a visiting location, the user's service profile is accessed to determine the user's group classifications (if any). The mobile station is assigned a TMSI number according to the user's accessed service profile and a portion of bits associated with the TMSI number are encoded based on the identifiable user group classification. The length of the assigned TMSI number may be adjusted depending upon the particular application to maximize the number of TMSI numbers that may be transmitted in a single paging slot.

Description

METHOD FOR ASSIGNING A TEMPORARY MOBILE STATION IDENTIFICATION NUMBER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to telecommunication systems and, more particularly, to a method for assigning a mobile station's temporary mobile subscriber identification number (TMSI) to provide telecommunication services to a particular user group classification. 2. Description of the Related Art With the increasing popularity of wireless telecommunication systems (eg, wireless cellular telecommunication systems), telecommunication service providers offer many different types of telecommunication services to their respective customers. Such services are generally provided to users based on a subscription and, therefore, such users are generally called "subscribers or subscribers". To facilitate such services, it is desirable that providers of wireless telecommunications networks classify mobile stations (eg, phones REF 29349). mobile manual and portable cell phones and other communication devices) that belong to specific subscribers or subscribers as an identifiable group for various services, such as sending a page to all members belonging to a specific group classification. To do this, it is necessary that the service provider be able to identify the user associated with a particular mobile station no matter where the mobile station is in the network and determine whether the particular user is subscribed to a specific group classification. In conventional cellular networks, each mobile station has a unique Mobile Identification Number (MIN) or International Mobile Subscriber Identification Number (IMSI) for identification purposes used in billing, record storage and the like. However, when a mobile station moves out of its place of residence served by a Mobile Switching Center (MSC) and enters a visiting place served by another MSC, the mobile station is assigned a Subscriber Identification Number. Temporary Mobile (TMSI) for purposes of identification similar to the MIN or IMSI in the use of the network. A conventional method for generating a TMSI is described, for example, in U.S. Patent No. 5,375,251, to Pfundstein. In telecommunications systems conventional wireless, the TMSI number is unique identification number, with randomly assigned frequency, which is typically 20-24 bits in length. In conventional systems, therefore, the TMSI number is not assigned to more than one user of a system serving that MSC at a time. Accordingly, the TMSI number is usually invalidated when the mobile station crosses to a new location served by a different MSC or after a predetermined period of time after the initial assignment of the TMSI number (eg, 12 hours). Consequently, because mobile stations frequently change location within the wireless network and are often controlled by different MSCs, it is problematic for conventional wireless telecommunications systems to effectively identify the user associated with a particular mobile station when the mobile station is outside of your place of residence to determine if that particular user is subscribed to a specific group classification. In a conventional wireless network, therefore, for paging or radiolocating all mobile stations belonging to a particular group of subscribers or subscribers to answer a call in parallel, it is now necessary for the calling party to send a separate page to the mobile station which corresponds to each member of the group. This procedure, however, it has proven to be inconvenient and does not provide sufficient flexibility to take into account the change in the location of mobile stations within the wireless network. As an alternative to sending a separate page to the mobile station corresponding to each member of the group, a group identification could be preprogrammed in a mobile station to identify the user of that mobile station as a member of a particular group. However, this procedure does not allow group members to be assigned dynamically (for example, as a function of location, time of day, day of the week, etc.).

BRIEF DESCRIPTION OF THE INVENTION The above problems are solved and advances are achieved over the prior art with the present invention by allocating a portion of the bits within a co-assigned allocated mobile station TMSI number based on a user's group classifications (i.e. , classifications based on the characteristics of the user, such as the services and affiliation of the subscriber). When the user of a mobile station requests service in a place of visit, the user's service profile is accessed to determine the user's group classifications (if any). The mobile station is assigned a TMSI number according to the service profile of the user's mobile station using the assigned bits. In addition, the length of the assigned TMSI number can be adjusted depending on the > particular application to maximize the number of TMSI numbers that can be transmitted in only paging or radiolocation interval.

BRIEF DESCRIPTION OF THE DRAWINGS The above characteristics and other aspects of the invention are explained in the following description taken in relation to the accompanying drawings in which: Figure 1 is a block diagram illustrating the interconnections between a mobile station, a ground-based station, a base station system, a public switched telephone network and a mobile switching center; and Figure 2 is a block diagram illustrating the method of assigning a TMSI according to the present invention to identify a group classification associated with a particular mobile station.

DETAILED DESCRIPTION OF THE INVENTION Although it should be understood that the present invention is not limited to cellular telecommunications networks, Figure 1 illustrates a cellular telecommunications system in which the present invention can be used. In such a system, conventional cellular technology is applied to allow the same frequencies of assigned radio bandwidth to be reused in local areas or cells of a wider region. Generally, each cell is served by a base station system 300 or 301 comprising a group of local transceivers connected to a common antenna. The base station systems 300, 301, each typically comprise a controller 310 and at least one transceiver 320, are interconnected via a switching system, commonly known as a mobile switching center (MSC) 200, 201. The MSC 200.201 is for switching calls involving at least one mobile station 20, 21 and also being connected to the public switched telephone network (PSTN) 100 to communicate with land-based stations 10. The base station system 300 and mobile station 20 communicate via radio connections. The base station system 300 is also connected via trunks to carry voice or data, and control messages between the mobile station 20 and MSC 200. It should be understood that the base station system 301 illustrated in Figure 1 operates in an identical manner with with respect to the mobile station 21 and the MSC 201.

Wireless telecommunications networks such as that illustrated in Figure 1 typically comprise many units that need to communicate signaling information to control the establishment of connections. Such signaling information is typically communicated on separate channels of the channels that currently carry voice or data communications between the users that are connected. Among the units that need to communicate are the mobile stations 20, 21, the systems of base station 300, 301 connected by radio to the mobile station 20, 21, the MSC 200, 201 and the different databases that are consulted for the establishment of the mobile calls (including the local location register (HLR) 210 , the visitor location record (VLR) 220, the authentication center (AUC) 230 and the equipment identification register (EIR) 240). The databases are described below with respect to the MSC 200. Although not illustrated, it should be understood that the MSC 201 contains separate databases from those of the MSC 200 and that the MSC 201 operates in an identical manner to the MSC 200. Furthermore, it should be understood that the HLR 210, AUC 230 and EIR 240 may be separate nodes of the associated MSC and may have direct access to them from other MSCs within the network . The HLR 210 contains data for a mobile client that is registered in the particular service area of the MSC 200. The data stored in the HLR 210 is the permanent data that is independent of the place where the customer is present within the wireless telecommunications network, plus temporary data such as the address of Service Centers that have stored short messages for a mobile station 20. Those addresses are deleted after having delivered the short messages. The HLR 210 also indicates the point code of the Signaling System 7 (SS7) used to find a module containing the VLR 220 currently associated with the mobile station 20. It is not expected, however, that a subscriber or subscriber is constantly in the service area of the same MSC 200 where the subscriber data is stored (residence location). Accordingly, each MSC 200, 201 generally comprises a VLR 220 that contains the current data for those mobile stations 20, 21 registered locally within the service area of the particular MSC 200, 201, including the area in which the mobile station is present. of the client or the most recently known area, the on / off status of the mobile station, and various security parameters. The AUC 230 generally provides the parameters of authentication and encryption or encryption to ensure that a mobile client does not falsely assume the identity of another mobile client and provides data to encrypt or encode voice or data, and control signals transmitted between the mobile station 20 and the base station system 300 The EIR 240 maintains a record of a range of certified equipment identifications and a range of individual equipment identifications which are under observation or are listed in the service. The equipment identification information is received from the mobile station 20 in the MSC 200 and the EIR 240 and is used to verify that the equipment number of the mobile station 20 is certified to be used in the network and not over the observation or list from service. In accordance with the present invention, a group of subscribers to cellular services can be classified as an identifiable group so that the network provider can offer group services to each group number. With reference to Figure 2, when a mobile station is first turned on within the cellular network, the Mobile Identification Number (MIN) or International Mobile Subscriber Identification Number (IMSI) unique to the mobile station is used by the mobile station. the mobile station in a conventional manner to identify and register with the MSC that it serves the data area within the network where the mobile station is located (SIO step). Such a record is generally achieved by determining which base station system and associated MSC provides the strongest signal to the mobile station. In this way, the location area of the mobile station within the cellular network is recorded by determining in which MSC the mobile station is registered. When a call is placed for the mobile station 20, the HLR 210 associated with the MSC 200 is first accessed and the call can pass through the conventional authentication processes. The local MSC is the MSC that contains the permanent data related to the particular mobile station 20 in its HLR 210. Among other things, the HLR 210 has stored within it a user profile corresponding to the particular subscriber or subscriber, user profile which is identifiable based on the MIN or IMSI associated with the mobile station 20 registered to the subscriber or subscriber. The user profile stored in the HLR 210 for each subscriber or subscriber includes information related to any group classifications to which the subscriber or subscriber is subscribed. In this way, based on the MIN or IMSI number associated with the mobile station being called, the local MSC can search for a user profile for the mobile station ue is being called (step S20). If the mobile station is registered in the service area of the local MSC, then the local MSC searches for a user profile associated with the mobile station being called to easily determine whether the mobile station has been classified in any group classifications. Alternatively, when the mobile station 20 is registered at a visit site with an MSC (service MSC) different from the local MSC (eg, the mobile station moves out of the service area of its local MSC and enters a visiting place served by another MSC), the local MSC containing the permanent HLR data for that mobile station identifies the serving MSC in a conventional manner and transmits a copy of the user profile associated with the mobile station of the serving MSC. In this way the user profile is stored in the VLR of the service MSC. At this time, the VLR of the serving MSC assigns a Temporary Mobile Subscriber Identification (TMSI) number to the mobile station 20 for identification purposes. However, instead of the TM? I number being assigned randomly or pseudo-randomly to temporarily identify a visiting mobile station, the TMSI number is assigned instead in a predefined format to identify any group classifications, at that the user of the mobile station can subscribe. For example, if the format of the TMSI number is 24 bits in length, one or more digits within the TMSI number can be used to specify whether the mobile station belongs to a group classification. Accordingly, before assigning the TMSI number, the serving MSC looks up the profile of the user received and stored in its VLR associated with the mobile station (step S30). If the user profile identifies a group of which the mobile station is a member, then the first digit of the TMSI number assigned by the VLR is set to "0" (step 350). Alternatively, if the mobile station is not a member of a group classification, then the first digit of the TMSI number assigned by the VLR is set to "1" to indicate the absence of group classification and the remainder of the TMSI number of 24 bits could be assigned randomly by the VLR (step S40). The examples of TMSI numbers assigned by the VLR according to the modality mentioned above are set out below: OAB C T T T T T T 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 where 0 - Individual / Group TMSI (0 - Group ID; 1 = individual); A B - Length of the TMSI (for example, 4/6/10/20 bits); and C - Issuance / absence of emission to identify the action taken by the mobile station when paging or radiolocalised .. According to the TMSI format identified above, the next 24-bit TMSI number could be assigned by the 'VLR to identify a TMSI of group emission of 6 bits (for example, passive receiver where the information is downloaded to all group members and no further action is required): O 1 0 0 T T T T T T 0 0 0 0 0 0 O O 0 0 0 O 0 O Similarly, the next 24-bit TMSI number would identify a TMSI without a 6-bit group broadcast (for example, active reception where information is downloaded to all group members and additional actions are required): O 1 O 1 T T T T T T O 0 0 0 O O O O O 0 0 0 0 0 The TMSI numbers assigned in accordance with the present invention are transmitted from the particular mobile station via paging or radiolocation intervals within the wireless network. A paging interval is an interval in the digital control channel used to page or radiolocate mobile stations and, for example, is approximately 100 bits in length according to Interim Standard TIA 136 (IS-136). Because the number and length of paging ranges within the network are limited, it is desirable to use each paging interval efficiently. In this way. , according to the present invention, a number of TMSI numbers of short groups can be assigned and sent economically within a single paging interval. In accordance with the present invention, the length of the assigned TMSI number may vary by the particular application. For example, short group TMSI numbers can be assigned for frequently located or large dispatch emission groups, and larger group TM? I numbers could be assigned for small hunting groups. In this way, a simple paging interval could effectively transport 3 individual pages and 1 to 5 group TMSI numbers. To facilitate the assignment of TMSI numbers of different length depending on the particular application, the TMSI number can be assigned in the following format, so that the first four digits indicate the type of TMSI number that is being transmitted: A P QRXXXX ... where A = Individual / Group TMSI (0 = group ID; 1 - individual); and PQR - length of the TMSI number. For example, a PQR of 001 - (1 x 20 bits); an assigned PQR of 010 = (1 x 10 bits) + (1 x 6 bits) + (1 x 4 bits); . . . an assigned PQR of 111 '= (5 x 4 bits). Although illustrative preferred embodiments have been described here in detail, it should be noted and appreciated by those skilled in the art that numerous variations may be made within the scope of this invention without departing from the principles of this invention and without sacrificing its main advantages. The terms and expressions have been used here as terms of descriptions and not as terms of limitation. There is no intent to use terms or expressions that exclude any equivalents or features shown and described or portions thereof and this invention shall be defined in accordance with the following claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (21)

1. A method for operating a wireless telecommunications network, the network has associated with it a group of at least one mobile station having an identifiable user group classification, the method characterized in that it comprises the steps of: (a) assigning a number of temporary identification to the mobile station belonging to the identifiable user group classification, the temporary identification number comprises a plurality of bits; and (b) encoding a portion of the plurality of bits based on the identifiable user group classification.

The method according to claim 1, characterized in that it further comprises the step of storing a stored user profile with the mobile station, the user profile identifies any user group classification assigned to the mobile station.

The method according to claim 2, characterized in that it further comprises the steps of: (a) recovering the user profile associated with the mobile station; Y (b) determining whether the mobile station was assigned an identifiable user group classification based on the recovered user profile.

4. The method according to claim 3, characterized in that the user profile is stored within a local location register (HLR) database.

The method according to claim 4, characterized in that it further comprises the steps of: (a) copying the recovered user profile associated with the mobile station; and (b) transmitting the copied user profile to a mobile switching center serving the mobile station.

The method according to claim 5, characterized in that the transmitted user profile is stored in a visited location registration database (VLR) associated with the mobile switching center.

The method according to claim 3, characterized in that the user profile associated with the mobile station is retrieved based on a permanent identification number assigned to the mobile station.

8. The method according to claim 7, characterized in that the permanent identification number assigned to the mobile station is the International Mobile Station Identification (IMSI) number of the mobile station.

9. The method according to claim 7, characterized in that the permanent identification number assigned to the mobile station is the Mobile Identification Number (MIN) of the mobile station.

The method according to claim 1, characterized in that at least one bit of the plurality of encoded bits identifies whether the mobile station is assigned to an identifiable user group classification.

The method according to claim 1, characterized in that the length of the assigned temporary identification number depends on the identifiable group classification in order to efficiently use the paging or radiolocation intervals within the wireless telecommunications network.

12. A method for classifying at least one mobile station within a wireless telecommunications network as an identifiable group classification, characterized in that it comprises the steps of: (a) storing a user profile associated with the mobile station, the user profile that identifies the classification of the group assigned to the mobile station; (b) assigning a temporary identification number to the mobile station belonging to the identifiable group classification, the temporary identification number comprises a plurality of bits; and (c) encoding a portion of the plurality of bits based on the identifiable user group classification.

The method according to claim 12, characterized in that at least one bit of the plurality of encoded bits identifies whether the mobile station was assigned to an identifiable user group classification.

The method according to claim 12, characterized in that it further comprises the steps of: (a) recovering the user profile associated with the mobile station; and (b) determining whether the mobile station was assigned an identifiable user group classification based on the recovered user profile.

15. The method according to claim 14, characterized in that the user profile is stored within a database of the registry of local location (HLR).

The method according to claim 15, characterized in that it further comprises the steps of: (a) copying the recovered user profile associated with the mobile station; and (b) transmitting the copied user profile to a mobile switching center serving the mobile station.

The method according to claim 16, characterized in that the transmitted user profile is stored in a visited location registration database (VLR) associated with the mobile switching center.

The method according to claim 14, characterized in that the user profile associated with the mobile station is retrieved based on a permanent identification number assigned to the mobile station.

The method according to claim 18, characterized in that the permanent identification number assigned to the mobile station is the International Mobile Station Identification Number (IMSI) of the mobile station.

20. The method of compliance with claim 18, characterized in that the permanent identification number assigned to the mobile station is the Mobile Identification Number (MIN) of the mobile station. The method according to claim 12, characterized in that the length of the temporary identification number depends on the identifiable group classification in order to efficiently use the paging or radiolocation intervals within the wireless telecommunications network.