Abstract:
Synchronizing database files of a central node with database files of a local node in which the central node is coupled to the local node via a communication link. The communication link performance being continuously monitored via a periodic signal sent back and forth between the central node and local node. Information indicative of the files of the central database are integrated with the monitoring signal portion sent from the central node to the local node and a determination is made whether the files integrated with the monitoring signal corresponds with files of the local database via indications in the monitoring signal portion returned from the local node.

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001]     The invention relates generally to telecommunications and, more particularly to auditing of node databases in a wireless telecommunication network.  
       BACKGROUND OF THE INVENTION  
       [0002]     The popularity of wireless telephony has grown at an exponential rate over the past several years. As an increasing number of people use wireless telephones as a substitute for traditional wireline telephones, telecommunications service providers must be ready to seamlessly provide service features and facilities normally associated with wireline service to the users of wireless telephony services.  
         [0003]     One important and government mandated service required in both wireline and wireless telephony is public safety administration services (also known as emergency or “911” services). The hallmark of 911 service is the ability of the emergency service personnel to view the address of a distressed caller while the call is ongoing. In wireline applications, 911 service is easily administered because the caller uses equipment associated with a fixed address or location. Indeed, the caller&#39;s address aids 911 personnel in identifying appropriate emergency services units to respond to the distressed caller&#39;s request. In resolving an emergency, the position information may be used by the emergency services network in a variety of ways. For example, it may be used to plot a point on a map, to provide the nearest known street address, or an input to navigation equipment in the emergency response vehicle.  
         [0004]     Wireless telephony poses an entirely new challenge for emergency service administration. Due to the very nature of wireless telephony, a distressed caller may be using a mobile unit in any geographic region where wireless service is provided. The challenge for emergency personnel and wireless service providers is to pinpoint the location of a distressed caller so that appropriate emergency service personnel may be dispatched.  
         [0005]     The Federal Communication Commission (FCC) has mandated that wireless telecommunication service providers include the capability to locate a mobile subscriber unit within a certain geographical area. Several technologies have emerged and are being developed to meet the government mandate, including, navigational systems such as the global positioning system GPS, wireless assisted GPS, angle of arrival, time difference of arrival, RF fingerprinting and enhanced forward link triangulation. These technologies offer various degrees of accuracy and technological superiority in locating a mobile subscriber unit. Concurrent with the emergence of these position determination technologies, several standards have emerged and are being developed for obtaining location information.  
         [0006]     Position information may be delivered to the emergency services network in two basic ways: with the call as part of the call setup information or through a separate data service. The former is known as Call Associated Signaling (CAS) since the position information is delivered in the call signaling. The latter is NCAS and the messages delivered by the data service must be correlated with the call by parameters carried in the message. With NCAS, an Emergency Services Message Entity pulls the position information from the wireless network. Thus, the wireless network uses the above-mentioned positioning technologies to position a mobile subscriber unit.  
         [0007]     The American National Standards Institute wireless standards committee (ANSI-41) examining the issues and technologies for meeting the FCC mandate (i.e., the wireless carrier must provide the coordinates of the mobile unit&#39;s position to a emergency call center) concluded that the basic functionality necessary for implementation should use non-call path associated signaling (NCAS) in order to meet the situational contingencies and be implemented in the intelligent network on a service control point.  
         [0008]     The Telecommunication Industry Association (TIA) Ad Hoc Emergency Services (AHES) committee developed a standard, which would eventually become a joint standard for ANSI-41 and GSM deployments of wireless emergency services—the J-STD-036. The standard develops a reference network model to describe the functional partitioning in which the functions are divided among several functional entities or nodes based on traditional functional separations.  
         [0009]     Many of these network nodes maintain databases for storing/correlating files identifying system resources needed for enabling mobile unit positioning. System resources can include mobile serving areas, controllers, and positioning equipment, for example. Successful communication between network nodes depends on accurate synchronization of files contained in the respective databases. This is particularly important in an emergency service networks. Therefore, a need exists for a method and system for auditing network node databases to effect accurate file synchronization.  
       SUMMARY OF THE INVENTION  
       [0010]     Briefly described, in a first preferred form the present invention comprises a method for synchronizing database files of a central node with database files of a local node in which the central node is coupled to the local node via a communication link. The communication link performance being continuously monitored via a periodic signal sent back and forth between the central node and local node. A determination is made whether the files of each database are synchronized by passing information in the monitoring signal.  
         [0011]     Moreover, information indicative of the central database files are integrated with the monitoring signal sent from the central node to the local node and a determination is made whether the files correspond with files of the local database via indications in the corresponding monitoring signal returned from the local node. The communication link can be a conventional IP link and the monitoring signal can be a conventional heartbeat signal.  
         [0012]     Moreover, each database file is sequentially included in successive heartbeats of the monitoring signal such that each heartbeat includes information representing a different database file. Preferably, the central node is a Mobile Positioning Center (MPC) and the local node is a Position Determining Equipment (PDE) in a wireless emergency services network which includes a plurality of Mobile Switching Centers (MSC) and a plurality of Cells associated therewith and each database file is an identifier corresponding to a unique MSC and Cell combination. Moreover, one way of carrying out the invention is to include a mobile unit geographical position request corresponding to a MPC database file in a heartbeat signal and then determining whether the returned heartbeat signal received from the PDE indicates an error with the position request. An error in the position request can be assumed to indicate that the MPC file did not match a file in the PDE database. In addition, a report can be generated listing any MPC file which corresponds to a position request indicated with an error. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  shows a network representing a conventional ANSI-41 reference model for “network based” emergency call support services in accordance with the J-STD-036 standard.  
         [0014]      FIG. 2  shows a conventional database arrangement for network nodes.  
         [0015]      FIG. 3  shows a flow diagram illustrating a conventional heartbeat communication scheme.  
         [0016]      FIG. 4  shows a flow diagram illustrating an audit method in accordance with exemplary embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     The present invention is directed to systems for auditing node databases in a wireless telecommunication network in which the audits are in real time or near real time. “Wireless” refers to cellular, Personal Communication Services, and other commercial mobile radio services and does not apply to cordless telephones or private radio systems. Methods and systems envisioned by the present invention minimize errors propagated in emergency caller location inquires due to database synchronization deficiencies.  
         [0018]     Referring now to  FIG. 1 , there is shown a network representing a simplified version of the ANSI-41 reference model  100  for “network based” emergency call support services in accordance with the J-STD-036 standard. “Network based” is a category of mobile positioning technology known in the wireless industry in which a conventional mobile network, in conjunction with network-based position equipment, is used to estimate the geographical position of a mobile station. The reference model  100  was developed to describe the functional partitioning in which the functions are divided among several functional entities or nodes based on traditional functional separations.  
         [0019]     Although aspects of the present invention are directed at network nodes of the mobile network portion  110 , a general understanding of the entire reference model  100  is helpful for a better understanding. The reference model  100  includes a mobile network portion  110 , a public safety answering point (PSAP)  130  and an emergency services network portion  120 .  
         [0020]     The emergency services network portion  120  is functional for routing calls and service request between the mobile network portion  110  and the PSAP  130  via an emergency services message entity (ESME) that is conventionally functional for routing and processing the out-of-band messages related to emergency calls and an emergency services network entity (ESNE) that is conventionally functional for routing and processing the voice band portion of the emergency call. The PSAP  130  is the terminating end-point (i.e., operator) responsible for answering to emergency services calls and arranging the emergency services (e.g., fire, police, ambulance).  
         [0021]     As above-mentioned, the mobile network portion  110  includes a conventional mobile network and positioning equipment. Typically, the mobile network includes several base station transceivers (BTS)  111  each serving a discrete geographical area or cell (which may be divided into several emergency zones) for communicating over a radio link with a mobile station (MS) making an emergency call. The mobile network also includes one or more mobile switching centers (MSC)  113  each associated with a select plurality of BTSs  111  (via appropriate hardware links). Thus, each MSC  113  is associated with a select plurality of cells. The MSC  113  is functional for providing conventional call management functions (i.e., setting up and tearing down connections for the call) and routing of emergency calls to the emergency services network portion  120 .  
         [0022]     The network-based position equipment includes position determining equipment (PDE)  117  devices functional for determining the geographic position of the MS when the mobile station user initiates a call or while the user is engaged in a call. Each PDE  117  is associated with a mobile position center (MPC)  115  that is functional for selecting the appropriate one or ones of a PDEs  117  to use for determining position. The MPC  115  is preferably a processor-based apparatus that uses stored computer programs to implement its functions in which aspects of the present invention can be implemented in computer programs. Alternatively, aspects of the present invention can be implemented with interface circuits, combination logic and/or sequential logic.  
         [0023]     Summarizing the network entity relationship of the three network nodes (i.e., MSC  113 , MPC  115 , PDE  117 ) of the mobile network portion  110 , each MSC  113  is associated with a plurality of cells. Further, the MSC  113  is assigned to only one MPC  115 , but each MPC  115  may be associated with multiple MSCs  113 . Additionally, each MPC  115  is associated with multiple PDEs  117  and each PDE  117  can be associated with multiple cells. The combinations of MSCs and cells serviced by a particular MPC  115  are contained in a database in the MPC  115  and in separate and independent databases in the associated PDEs  117 .  
         [0024]     In conventional operation, a 911 emergency call from the MS is routed to the MSC  113  which routes the 911 call to the emergency services network portion  120  for further routing to the appropriate PSAP  130 . Along with the routed call, the MCS  113  includes identification of both the serving cell and MSC. The MCS  113  may also send this id information to its assigned MPC  115 . Subsequently, the PSAP  130  may request or query mobile positioning information for the MS via the emergency services network portion  120 , which pulls the position information from the MPC  115 . The request incorporates information identifying the serving cell and MSC  113 , and the MPC  115  correlates this information with that received from the MSC  113  for selecting which PDEs  117  to be used for determining the position of the MS.  
         [0025]     Referring to  FIG. 2  there is shown a table for illustrating a conventional database arrangement for the MPC  115  and PDE  117 . The first column represents a list of numerical values each representing a MSC and one of the cells serviced by that MSC. The MSCs and cells each have their own assigned identification numbers, known in the wireless industry as MSCID and CELLID, respectively. Thus, each numerical value in the first column is correlated with a MSCID/CELLID combination. In this example, the value zero “0” represent the combination of MSC number 2020 and cell number 24001. As can be seen, MSC number 2020 may have several cell combinations.  
         [0026]     The success of emergency caller location quires depends on the accuracy of MSC id and cell id information stored with the MPCs and PDEs. For example, if for any reason a PDE  117  does not recognize the MSCID/CELLID combination in a position request from a MPC  115 , the precision of a location estimate will be adversely affected if it can be generated at all.  
         [0027]     Thus, to maintain proper functionality, databases should be synchronized to contain the same id information. Synchronization is typically a process of inputting the MSCID and associated CELLID data manually into each database. To assure accuracy, synchronization should be performed whenever a new cell is added and/or re-configured, for example. As a practical matter, though synchronization is most often performed for the MPCs, it is not always performed on every PDE following a cell modification. This is due, in some part, to the fact that there are many more PDEs in the network than are MPCs. In addition, data entry errors can be made while updating network node databases.  
         [0028]     In accordance with exemplary embodiments of the present invention, network node databases are proactively audited to provide proper synchronization of stored information. More specifically, database entries of the MPC  115  and PDE  117  are continuously compared in a real-time manner to determine if there are any discrepancies. Discrepancies can be noted in a daily log or other type of periodic report. The auditing is provided via standard protocols, interface connections and connection monitoring between the MPC  115  and PDE  117 .  
         [0029]     The J-STD-036 standard defines the protocols and messages used on the network interfaces between the reference model  100  network entities. The interface between the MPC  115  and the PDE  117  is known as the E5 interface. In practical deployment, the E5 interface is an Internet Protocol (IP) connection. However, one problem with IP connections is that long periods of silence can cause connection loss. To ensure interface stability, an application level heartbeat message is typically used between the MPC  115  and PDE  117  simply for monitoring the connection. Thus, the MPC  115  exchanges heartbeat signals (HB) with the PDE  117  for determining that the IP connection is active (i.e., functioning properly). When the MPC  115  or PDE  117  recognizes that the HB sequence has been interrupted, both nodes initiate interface termination and re-establishment procedures.  
         [0030]     Referring now to  FIG. 3 , there is shown a flow diagram more particularly illustrating the above-mentioned conventional HB communication scheme. The method is initiated with the beginning of the HB at step  302  followed by the “MissedHB” counter (step  304 ). MissedHB is a counter variable that represents the number of consecutive occurrences of missed HBs (i.e., no return HB from the PDE  117 ). Subsequently, the MPC  115  sends the HB (step  306 ) to the PDE  117  and awaits a corresponding HB response (step  308 ).  
         [0031]     If a HB response is returned from the PDE  117  (step  308 ), the MissedHB count is set to zero and control is passed to the entry point (step  318 ) in anticipation of the next HB signal. If no HB response is returned from the PDE  117 , the MissedHB count in incremented by one (step  310 ) and the new count is compared to the “MaxMissedHB” (step  312 ). MaxMissedHB is a parameter that is set to the highest acceptable number of consecutive missed HBs. If the MaxMissedHB count is exceeded, the appropriate system nodes initiate Interface termination and re-establishment procedures step ( 314 ) and the MissedHB is set back to zero (step  316 ) and control is passed to the entry point (step  318 ) of the flow diagram for preparation of the next HB signal. If the MaxMissedHB is not exceeded, control is passed to the entry point (step  318 ).  
         [0032]     In accordance with a preferred embodiment of the present invention, database auditing is enabled by enhancing the above-mentioned conventional HB scheme. More specifically, functionality is enhanced by including database entries or files in a GPOSREQ(HB) signal between the MPC  115  and PDE  117 . In other words, in accordance with the J-STD-036 standard, a HB signal is implemented by means of a pre-defined timed geo position request (GPOSREQ) signal from the MPC  115  to the PDE  117  with the request type (REQTYPE) parameter set to HB (i.e., Heartbeat) and further including a database file from the MPC  115  with the HB signal. The MPC  115  cycles through its database files (i.e., MSCID/CELLID combinations) including one entry in each HB signal sent to the PDE  117 , each successive HB signal containing a different database entry. If the enhanced HB signal creates some type of error in the PDE&#39;s functionality, the PDE  117  returns an error indication in the HB signal. From an error indication, it can be assumed that the MPC database file was not recognized by the PDE  117 . In the alternative, the geo position directive from the PDE  117  can be used to check database entries. Here, database files from the PDE  117  are included with the HB signal. The PDE  117  cycles through its database files including one entry in each HB signal sent to the MPC  115 , each successive HB signal containing a different database entry. If this enhanced HB signal creates some type of error in the MPC&#39;s functionality, the MPC  115  returns an error indication in the HB signal. From an error indication, it can be assumed that the PDE database file was,not recognized by the MPC  115 .  
         [0033]     Referring to  FIG. 4  there is shown a flow diagram illustrating the inventive audit method. Following initiation of the HB (step  302 ), the MissedHB counter is set to zero and the MSCID/CELLID value from the MPC  115  database is set to zero (step  404 ). Subsequently, the MPC  115  sends the GPOSREQ(HB) with the current MSCID/CELLID value to the PDE  117  (step  406 ) and awaits the PDE&#39;s response (step  308 ).  
         [0034]     If no response is received, the control passes to steps  310 ,  312 ,  314 ,  316  and  318  as described and shown in  FIG. 3 . However, if a response is received, the HB is set to zero (step  320 ) and a determination is made as to whether the response is “normal” (i.e., does it indicate any errors) (step  422 ). If a determination is made that the response is normal, the MPC  115  assumes the database entries match properly (step  424 ) and the MCEID/CELLID value is incremented to the next combination (step  426 ). Control is then passed to the entry point (step  318 ) in anticipation of the next HB.  
         [0035]     If a determination is made that the response indicates an error, it is an indication that the PDE  117  database does not contain the current MSCID/CELLID value (step  428 ). Subsequently, the MPC  115  includes this entry in a problem log (step  430 ). The problem log can be an ASCII text based log file, for example, that the MPC  115  generates. The problem log contains unrecognized MSCID/CELLIDs and is deliverable to the system operator for review and/or correction. Following step  430 , control is passed again to step  426  for incrementing the MSCID/CELLID value to the next combination. In a preferred embodiment, the above-described auditing method is embodied on computer-readable medium associated with the MPC  115 .  
         [0036]     Of course, it should be understood that the order of the steps and/or acts of the step or algorithms discussed herein may be accomplished in different order depending on the preferences of those skilled in the art. Furthermore, though the invention has been described with respect to a specific preferred embodiment, many variations and modifications will become apparent to those skilled in the art upon reading the present application.