Abstract:
A communication system includes a plurality of first entities. Each of the plurality of first entities includes at least one database. The system also includes at least one second entity being dedicated to at least one of the plurality of first entities. The at least one second entity includes data from databases associated with the plurality of first entities. The system further includes a third entity for determining when one of the plurality of first entities malfunctions and for selecting another one of the plurality of first entities as a redundant entity. The at least one second entity is associated with the redundant entity and data is retrieved from the at least one second entity to process incoming requests to the redundant entity.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority of U.S. Provisional Patent Applications Ser. No. 60/578,878, filed on Jun. 14, 2004. The subject matter of the earlier filed application is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to mobile communications systems and more particularly to a mobile communications system which includes a redundant register network for automatically controlling and supervising units in a switching system.  
         [0004]     2. Description of the Related Art  
         [0005]     Mobile communications systems include a switching unit which is responsible for performing call processing and subscriber related functions. The switching unit includes various units for storing and processing subscriber information. For example, the switching unit includes a Home Location Register (HLR) which is a database for storage and management of subscriptions. The HRL stores permanent data for subscribers, including a service profile, location information and activity status for each subscriber. Specifically, HLR subscriber information includes a International Mobile Subscriber Identity (IMSI), service subscription information, location information which includes the identity of a currently serving Visitor Location Register (VLR) to enable routing of mobile-terminated calls, service restrictions and supplementary services information. In addition to the HRL, the switching system includes an authentication center (AUC) which is a unit that provides authentication and encryption parameters that verify the user&#39;s identity and ensure the confidentiality of each call. The switching system also includes an equipment identity register (EIR) which is a database that includes information about the identity of mobile equipment to prevent calls from stolen, unauthorized or defective mobile stations.  
         [0006]     Traditional communications network design is based on the utilization of a single Home Location Register (HLR) for each network. However, growth considerations and the creation of multi-vendor networks have prompted carriers to implement multiple HLR topologies. During operation of the communication system, the HLR, AUC, and/or EIR may become dysfunctional. When the one of these units goes out of order, current communications systems cannot automatically detect the out-of order status. As such, there is no way to automatically control and supervise HLRs AUCs and/or EIRs in a multi-vendor redundancy solution.  
       SUMMARY OF THE INVENTION:  
       [0007]     According to one embodiment of the invention, a communication system includes a plurality of first entities. Each of the plurality of first entities includes at least one database. The system also includes at least one second entity being dedicated to at least one of the plurality of first entities. The at least one second entity includes data from databases associated with the plurality of first entities. The system further includes a third entity for determining when one of the plurality of first entities malfunctions and for selecting another one of the plurality of first entities as a redundant entity. The at least one second entity is associated with the redundant entity and data is retrieved from the at least one second entity to process incoming requests to the redundant entity.  
         [0008]     Additionally, the third entity may be configured to supervise and control the plurality of first entities by sending a predetermined message to at least one unit in each of the plurality of first entities. The third entity may be configured to determine a malfunctioning one of the plurality of first entities when the malfunctioning one does not respond to the predetermined message. Furthermore, the redundant entity may be configured as an empty entity, each of plurality of first entities may be configured to communicate with at least one subscriber entity and the system may include a database interface for communications with at least one external database.  
         [0009]     Additionally, the third entity may be configured to perform load sharing among the plurality of first entities when one of the plurality of first entities malfunctions. The third entity may be configured to create test subscribers in each of the plurality of first entities. The third entity uses the test subscriber to determine which of the plurality of first entity is a malfunctioning entity. The third entity may also be configured to divide the test subscribers among the plurality for first entities in a round robin fashion. The third entity may also automatically create a test subscriber in one of the plurality for first entities when the third entity determines that the test subscriber is missing from the one of the plurality of first entities.  
         [0010]     According to another embodiment of the invention, a method for selecting a redundant entity includes the step of creating at least one second entity being dedicated to at least one of a plurality of first entities. The at least one second entity comprising data from databases associated with the plurality of first entities. The method also includes the steps of determining when one of the plurality of first entities malfunctions and selecting another one of the plurality of first entities as a redundant entity, wherein the at least one second entity is associated with the redundant entity. The method further includes the step of retrieving data from the at least one second entity to process incoming requests to the redundant entity.  
         [0011]     Additionally, the step of determining when one of the plurality of first entities malfunctions further includes the steps of supervising and controlling the plurality of first entities by sending a predetermined message to at least one unit in each of the plurality of first entities and determining a malfunctioning one of the plurality of first entities when the malfunctioning one does not respond to the predetermined message. The method may also include the step of enabling each of plurality of first entities to communicate with at least one subscriber entity.  
         [0012]     Additionally, the step of selecting may further include the step of performing load sharing among the plurality of first entities when one of the plurality of first entities malfunctions. Prior to the step of determining when one of the plurality of first entities malfunctions, the method further includes the step of creating test subscribers in each of the plurality of first entities. The test subscribers are used to determine which of the plurality of first entity is a malfunctioning entity. The may also include dividing the test subscribers among the plurality for first entities in a round robin fashion and automatically creating a test subscriber in one of the plurality for first entities when a determination is made that the test subscriber is missing from the one of the plurality of first entities.  
         [0013]     According to another embodiment of the invention, an apparatus for selecting a redundant entity includes creating means for creating at least one second entity being dedicated to at least one of a plurality of first entities. The at least one second entity includes data from databases associated with the plurality of first entities. The apparatus also includes determining means for determining when one of the plurality of first entities malfunctions and selecting means for selecting another one of the plurality of first entities as a redundant entity. The at least one second entity is associated with the redundant entity. The apparatus also includes retrieving means for retrieving data from the at least one second entity to process incoming requests to the redundant entity. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS:  
       [0014]     For proper understanding of the invention, reference should be made to the accompanying drawings, wherein:  
         [0015]      FIG. 1  illustrates a communications network in which the present invention may be implemented;  
         [0016]      FIG. 2  illustrates a subsystem which includes multiple HLRs;  
         [0017]      FIG. 3  illustrates the steps implemented in a multi-vendor system which provides a full redundant register network. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0018]     Reference will now be made to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0019]      FIG. 1  illustrates a communications network in which the present invention may be implemented. The communications network of  FIG. 1 , for example a GSM network, includes a mobile station (MS)  102 , a base station subsystem (BSS)  104  and a network subsystem  106 . MS  102  is carried by a subscriber. BSS  104  controls the radio link with MS  102  and network subsystem  106  performs the switching of calls between the mobile users and between mobile and fixed network users.  
         [0020]     MS  102  includes a mobile equipment/terminal  110  and a Subscriber Identity Module (SIM)  108 . SIM  108  provides personal mobility, so that the user can have access to subscribed services irrespective of a specific terminal. Mobile equipment  110  is uniquely identified by an International Mobile Equipment Identity (IMEI). SIM  108  includes an International Mobile Subscriber Identity (IMSI) which is used to identify the subscriber to the system, a secret key for authentication, and other information. The IMEI and the IMSI are independent, thereby allowing personal mobility. SIM  108  may be protected against unauthorized use by a password or personal identity number.  
         [0021]     BSS  104  includes Base Transceiver Stations (BTS)  112   a - 112   x  and Base Station Controllers (BSC)  114   a - 114   x . Each BTS  112  houses radio transceivers that define a cell and handles the radio-link protocols with MS  102 . Each BSC  114  manages the radio resources for one or more BTS  112  and handles radio-channel setup, frequency hopping, and handovers.  
         [0022]     Network Subsystem  106  includes a Mobile services Switching Center (MSC)  116  which acts like a normal switching node of a Public Switched Telephone Network (PSTN) or ISDN  108 . MSC  116  additionally provides, in conjunction with several functional entities of network subsystem  106 , all the functionality needed to handle a mobile subscriber, such as registration, authentication, location updating, handovers, and call routing to a roaming subscriber. MSC  116  provides connection to fixed networks such as the PSTN or ISDN. Signaling between functional entities in Network Subsystem  106  uses Signaling System Number  7  (SS 7 ). Specifically, a Home Location Register (HLR)  118  and a Visitor Location Register (VLR)  120 , together with the MSC  116 , provide the call-routing and roaming capabilities of the network. HLR  118  includes all the administrative information of each subscriber registered in the corresponding network, along with the current location of mobile station  102 . VLR  120  includes selected administrative information, from HLR  118 , necessary for call control and provisioning of the subscribed services for each mobile station currently located in a geographical area controlled by VLR  120 .  
         [0023]     Network Subsystem  106  further includes a Equipment Identity Register (EIR)  124  which is a database that includes a list of all valid mobile equipment  110  on the network, where each MS  102  is identified by its IMEI. Network Subsystem  106  also includes an Authentication Center (AuC)  126  which is a protected database that stores a copy of a secret key stored in each subscriber&#39;s SIM  108 . The secret key is used for authentication and encryption over the radio channel.  
         [0024]     When a mobile subscriber roams into a new location, VLR  120  associated with the new location automatically determines that it must update HLR  118  with the new location information, which it does using an SS 7  Location Update Request Message. The Location Update Message is routed to HLR  118  through the SS 7  network. HLR  118  responds with a message that informs VLR  120  whether the subscriber should be provided service in the new location.  
         [0025]     In current networks, it has become necessary to add more HLRs  118  to the network. This requirement might be prompted by a service subscription record storage capacity issue, or perhaps an SS7 message processing performance issue. It might possibly be prompted by a need to increase the overall network reliability. However, during operation of network  100 , any of HLR  118 , AUC  126  and/or EIR  124  may go out of order.  FIG. 2  illustrates a subsystem  210  which includes multiple HLRs. According to  FIG. 2 , subsystem  210  also includes two Service Routing Registers (SRR)  202   a  and  202   b . In current networks, however, the SRR does not have load sharing and observation capabilities over the HLRs. Thus, if one HLR goes down, the other active HLRs cannot take over the traffic of the defunct HLR without the risk of being overloaded.  
         [0026]     In at least network embodiment of the present invention, each of SRR  202   a  and  202   b  has load sharing and observation capabilities over all registers, such as HLRs  118 , AUC  126  and/or EIR  124 . According to one embodiment of the invention, each of SRR  202  includes a process which controls testing and performs analyses on the condition of the registers or HLRs  118 . Thus, if one HLR  118  is not functioning properly, another HLR can take over the traffic of the defunct HLR. It should be noted that while the discussion below is directed to the HLR, the inventive system may be used to handle redundancy issue related to other registers, such as AUC  126  and/or EIR  124 .  
         [0027]     In one embodiment of the invention, one of the HLRs  118 , for example HLR  118   d , is an empty HLR entity and is used for redundancy. Each of HLR  118  has a corresponding HLR redundancy server (HRS)  204   a - 204   x . HRS  204   d  which corresponds to HLR  118   d  includes a register of all the subscribers of all HLRs  118 . HLR  118  is in communications with one or more units, for example, an AUC provisioning unit  212 , an OSS unit  214  and a subscriber provisioning unit  216 . Subsystem  106  is connected to a database  206  so that the system can be provisioned from the database. According to an embodiment of the invention, database  206  may include multiple SQL databases  208   a - 208   x  such that databases  208  work as a realtime work station of network  100 . Each of HRS  204  includes an ODBC interface for working with databases  208 . It should be apparent to one of ordinary skill in the art that a common SQL database can be used in place of databases  208  for common provisioning from one source.  
         [0028]     In one embodiment of the inventive system, when one of HLR  118 , AUC  126  and/or EIR  124  goes to out of order, the out-of-order status is automatically observed and a new unit is selected in its place. Specifically, SRR  202  controls all registers in network subsystem  106  by sending a heart beat to each register and/or every database unit in the register. If there is a problem with a register, the register will not reply to the heart beat message from SRR  202 . SRR  202  then performs an analysis of the available working registers to select a new register to replace the malfunction register. So for example, when one of HLR  118  goes out of order, SRR  202  automatically detects the malfunction and enables network  100  to select a replacement HLR  118   d , i.e. the empty HRL entity, from one of the functioning HLRs. According to an embodiment of the invention, SRR  202  controls all HLRs  118  by sending heart beat messages to each HLR  118  in a predefined time interval. SRR  202  sends a RestoreData message to every HLR  118  and to every database unit in each HLR  118 . If there is a problem with one of the HLRs  118 , for example HLR  118   a , HLR  118   a  will not reply to the heart beat message from SRR  202 .  
         [0029]     According to an embodiment of the invention, there are test subscribers in each HLR  118  and/or every HLR database unit. The test subscribers are created with the assistance of subscriber entities  212  and  216  of  FIG. 2  and OSS  214 . The test subscribers are regularly polled by SRR  202  with the RestoreData message. When all RestoreData operations related to a specific test subscriber fail, SRR  202  knows in which HLR unit the unsuccessfully polled subscriber resides and concludes that this HLR unit is unreachable. This causes SRR  202  to internally analyze the available working registers and to forward calls related to an HLR deemed non-functioning, for example HLR  118   a , to a redundant HLR, for example HLR  118   d . By choosing empty HLR  118   d  as the replacement HLR, the invention ensures that the redundant HLR can process the traffic for the dysfunctional HLR without the risk of being overloaded. It should be apparent to one of ordinary skill in the art, that the SRR  202  may select a non empty HLR as the redundant HLR and still maintain the benefits of the inventive system. SRR  202  then reroutes all subsequent service requests associated with the dysfunctional HLR  118   a  to redundant HLR  118   d . Redundant HLR  118   d  retrieves the subscriber information for the new service requests from its associated HRS  204   d.    
         [0030]     The present invention therefore provides fast detection and recovery of HLR failure. The present invention also provides automated switchover to redundant HLR  118   d . Furthermore, the present invention overcomes load sharing issues between HLRs due to failures in a multi-vendor environment.  
         [0031]     In one embodiment of the invention, there may be several HLR units in a single HLR, for example in HLR  118   a . In this embodiment, there may be a threshold value configured in SRR  202  for determining the minimum number of HLR units that are required to be found simultaneously dysfunctional in order for SRR  202  to route subsequent service request associated with the determined dyfunctional HLR to the redundant HLR.  
         [0032]     In the inventive system, SRR  202  polls test subscribers every HLR  118  with a RestoreData MAP operation over SS 7  as a heart beat message. If SRR  202  observes that one of HLR  118  does not respond, SRR  202  reroutes all subsequent service request associated with the defunct HLR to the redundant HLR. After the switch over to the redundant HLR, if a non-test subscriber&#39;s information is missing from the redundant HLR, the subscriber information is automatically created from one of HRS  204  or SQL database  208 . In an embodiment of the invention, SRR  202  may reroute all subscribers which belong to a broken HLR to other working HLRs. The inventive system therefore ensures that there is a full automatic redundant control for service registers, for example, HLR  118 , AUC  126  and EIR  124 .  
         [0033]      FIG. 3  illustrates the steps implemented in an embodiment of the inventive system. In Step  3010 , SRR  202  controls all HLRs  118  by sending a RestoreData message to test subscribers in each HLR  118  and every HLR database unit in a predefined time interval. In Step  3020 , if there is a problem with one of the HLRs  118 , the dysfunctional HLR  118  will not reply to the heart beat message from SRR  202 . In Step  3030 , SRR  202  internally analyzes the available working registers and forwards calls for the non-functioning HLR  118  to a redundant HLR. In Step  3040 , SRR  202  then reroutes all subsequent service requests associated with the dysfunctional HLR  118  to the redundant HLR  118 . In Step  3050 , the redundant HLR  118  retrieves the subscriber information for new service requests from its associated HRS  204 .  
         [0034]     One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.