Patent Publication Number: US-8538454-B2

Title: Customized location area paging

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 11/736,207, filed on Apr. 17, 2007, now U.S. Pat. No. 7,787,889, issued on Aug. 31, 2010, the entirety of which is herein incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to wireless communications systems and, more particularly, to paging mobile devices in a wireless communications system. 
     BACKGROUND 
     In Global System for Mobile communications (GSM) and Universal Mobile Telecommunications System (UMTS), location areas (LA) are used to define the cells which will be paged to locate a particular mobile station (MS). Location areas are defined by the mobile operator and assigned a Location Area Identity (LAI). The LAI uniquely identifies a LA within the network. The LAI typically comprises a Mobile Country Code (MCC) to identify the country in which the network resides; a Mobile Network Code (MNC) to identify the network; and a Location Area Code (LAC) to identify the LA. 
     Typically, when a mobile terminated call, message, or page is sent to a MS, it is routed to the MS&#39;s last known LA. If the MS does not respond to the first attempt, the call, message, or page is routed to all the LAs associated with the Mobile Switching Center (MSC). The second MSC-wide paging attempt utilizes a significant amount of Base Station Subsystem (BSS) and MSC resources, and associated interfaces. In some instances, a mobile operator may choose to page the last known LA additional times in an effort to reach the MS; however, these attempts are often not successful. 
     Customized paging systems have been developed in an effort to decrease the paging area and accordingly decrease the use of network resources. In one such system, a mobile operator defines a LA based on the particular roaming habits of a mobile subscriber. The LA employs a predetermined grouping of cells arranged in the order of likelihood that the mobile subscriber will be in that grouping. This system merely stores the cells the subscriber most often frequents to define the LA. 
     In another paging system, the last known cell that is sufficiently interior to a LA causes the system to page only that LA. In contrast, when the last known cell is sufficiently towards the border of a LA, that LA is paged as well as the bordering LA(s). 
     These prior art systems, however, do not allow a mobile operator to define customized location areas based upon at least the time, date, and duration in which a subscriber is in communication with a particular cell or group of cells. 
     SUMMARY 
     The various embodiments of the present invention overcome the shortcomings of the prior art by providing methods for determining a customized location area (CLA) for a subscriber in a cellular network. One such method includes the steps of monitoring the cell to which a mobile station registers; storing data corresponding to the cell within a database; determining at least one CLA based upon the data, the CLA each including at least one cell; storing said at least one CLA; utilizing a predictive algorithm to determine which CLA the mobile station is currently located within, if at least two CLAs are stored; and paging each of the cells associated with the appropriate CLA. 
     In one embodiment, the data is at least one of the following: the frequency which the mobile station registers with the cell, the time the mobile station registers with the cell, the date the mobile station registers with the cell, and the time duration the mobile station is registered with the cell. 
     In another embodiment, the predictive algorithm utilizes at least one of a last known location and a priority level to determine which CLA the mobile station is currently located within. 
     Another method according to the present invention includes the steps of establishing communication between a mobile station and a cell; acquiring a cell identification corresponding to the cell and storing the cell identification in a network database; storing a start time when the mobile station establishes communication with the cell; enabling a frequency counter, the frequency counter being configured to track the number of times the mobile station establishes communication with the cell; incrementing the frequency counter; storing the frequency counter value; terminating communication with the cell; storing a stop time when the mobile station terminates communication with the cell; calculating a duration from the start time and the stop time; storing the duration; establishing communication with at least one subsequent cell; performing each of the steps for the subsequent cell; determining a CLA based upon the data acquired during the steps for each of the cells, the data including the cell identification, the start time, the frequency counter, the stop time, and the duration; storing the CLA; and paging each of the cells associated with the CLA. 
     The foregoing has broadly outlined some of the aspects and features of the present invention, which should be construed to be merely illustrative of various potential applications of the invention. Other beneficial results can be obtained by applying the disclosed information in a different manner or by combining various aspects of the disclosed embodiments. Accordingly, other aspects and a more comprehensive understanding of the invention may be obtained by referring to the detailed description of the exemplary embodiments taken in conjunction with the accompanying drawings, in addition to the scope of the invention defined by the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a network schematic in accordance with an exemplary embodiment of the present invention. 
         FIG. 2  illustrates a system diagram of a Global System for Mobile communications (GSM) network, in accordance with the present invention. 
         FIG. 3  illustrates a block diagram of an exemplary method for acquiring location data, determining a customized location area, and selecting a page-to location area, according to the present invention. 
         FIG. 4  illustrates a block diagram of an exemplary method for tracking and storing location data, according to the present invention. 
         FIG. 5  illustrates a block diagram of an exemplary method for determining a customized location area for a subscriber, according to the present invention. 
         FIG. 6  illustrates a block diagram of an exemplary method of a predictive algorithm for determining which location area to page, according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As required, detailed embodiments of the present invention are disclosed herein. It must be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms, and combinations thereof. As used herein, the word “exemplary” is used expansively to refer to embodiments that serve as an illustration, specimen, model or pattern. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. In other instances, well-known components, systems, materials or methods have not been described in detail in order to avoid obscuring the present invention. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention. 
     Referring now to the drawings in which like numerals represent like elements throughout the several views,  FIG. 1  illustrates a cellular network  100  in accordance with an embodiment of the present invention. The cellular network  100  includes three location areas: LA 1 , LA 2 , and LA 3 . LA 1  includes cells  1 - 9 ; LA 2  includes cells  10 - 18 ; and LA 3  includes cells  19 - 27 . By way of example, a user of a mobile station (MS)  102  resides in LA 1  and is served by the base station  104  of cell  7 . By further example, this user works in LA 2  and, in particular, his office is located in cell  18 . Accordingly, the user travels between cells  7  and  18  during his/her normal work week (e.g., Monday through Friday, 9 AM to 5 PM). During his commute the user traverses cells  8 ,  9 ,  13 ,  16 , and  17 . The user&#39;s morning commute is labeled as path  106 . 
     By way of example, in the evening, the user commutes home via a different path in an effort to avoid traffic. This path is labeled as path  108 . Path  108  starts at cell  18  and traverses cells  15 ,  12 ,  11 ,  26 ,  10 ,  6 , and  5 , and ends at cell  7 . 
     In addition to the generic location areas established by the mobile operator (i.e., location areas LA 1 , LA 2 , and LA 3 ), the mobile operator can establish one or more customized location areas (CLAs) for a subscriber, in accordance with an embodiment of the present invention. The CLAs are used to page a particular subscriber&#39;s MS instead of or prior to paging one or more generic location areas. The customized location areas are defined by the aforementioned paths and will be referred to hereafter by the reference numeral assigned to each of the paths. 
     Moreover, CLAs can be defined for specific dates and times such as those previously described with regard to the user&#39;s path  106  from their home (cell  7 ) to their office (cell  18 ) in the morning and the user&#39;s path  108  from their office to their home in the evening. It is contemplated that specific times or time ranges can be used to define at least in part a CLA for a particular subscriber. 
     In addition to paths  106  and  108 , the user may have a weekend routine that requires him to travel, for example, from cell  7 , through cells  4 ,  1 ,  2 ,  3 ,  22 ,  19 ,  20 ,  23 ,  25 ,  6 , and  8 , and back to cell  7 . This exemplary path is illustrated and labeled as path  110 . If the network needs to page the MS  102  during the weekend, paging the CLA defined by the cells of path  106  and/or path  108  would not be appropriate and would unnecessarily utilize network resources. Accordingly, the present invention would identify the day (i.e., a Saturday or Sunday) and choose the CLA(s) appropriate for the day, which in this case is the CLA defined by the cells inclusive to path  110 . 
     The CLAs can be any size as determined by the mobile operator. For example, a CLA may include one or more generic LAs, or further defined such as the aforementioned CLAs for paths  106 ,  108 , and  110 . In addition, the mobile operator can define one or more customized location sub-areas (CLSAs) defined as portions of a parent CLA. In another embodiment, a CLSA can include multiple CLAs or portions thereof. This can allow for further improvement in paging accuracy and precision in an effort to reduce the network resources needed to determine the location of a MS by reducing the total area (in cells) paged. 
     An exemplary use of a CLSA is now described. For example, the user may stop for breakfast on Tuesdays and Thursdays during his work week. In this example, suppose the user must travel outside of his usual path  106  to cell  5 . Accordingly, a CLSA can be defined to include the additional cell, cell  5 . The CLSA can then be added to the cells of the parent CLA and accordingly paged, or can be paged individually. Further, a time range (e.g., 7:00 AM to 7:45 AM) can be defined for the time during which the user will likely be in this CLSA. This further reduces the number of unnecessary pages. Methods for acquiring location data such as, but not limited to, including date, time, duration, frequency, and cell sequences are described in further detail with referenced to  FIGS. 3-6 . 
     Another example of the use of a CLSA is the addition of cell  5 , the cell in which the user&#39;s breakfast restaurant resides, to the CLA defined by path  106 . The corresponding combination CLA and CLSA would include cells  7 ,  5 ,  8 ,  9 ,  13 ,  16 ,  17 , and  18 . In one embodiment, the combination CLA could be modified to only include cell  5  during the specified times. An indication as to this modification can be stored with the other location data in an appropriate database. 
     The aforementioned variables for date, time of day, and duration can be used in any combination or individually to determine a CLA for a particular subscriber. The frequency a subscriber is in a particular cell or group of cells can also be used to determine a CLA. In some embodiments, frequency can be used initially to determine which cells a subscriber frequents. Over time, the time of day and/or calendar day can be used to further define a CLA for the subscriber. The sequence of cells traveled through can also be used to define a CLA. An exemplary method for determining a CLA is described with reference to  FIG. 4 . 
     The mobile operators can determine the complexity of the CLA(s) and CLSA(s) for each subscriber. These determinations are made based upon historical location data provided to the mobile operator&#39;s network via registration processes. Over time, the mobile operator can develop more detailed and consequently more accurate and precise CLAs and CLSAs appropriate for each subscriber or group of subscribers. 
     It is likely that some cells or generic LAs may experience higher subscriber traffic and, as a result, paging resources may be more limited in these cells or LAs. Thus, it may be beneficial for the service provider to have particularly detailed CLAs and/or CLSAs for the subscribers that frequent these areas so as to eliminate unneeded page attempts. 
     It should be understood that although a single subscriber is described with reference to  FIG. 1 , a group of subscribers can be associated with a CLA and/or a CLSA. The subscriber&#39;s designation in a particular group can be modified as the subscriber&#39;s historical location data changes. 
       FIG. 2  illustrates an exemplary Global System for Mobile communications (GSM) network  200  that can be used to implement the present invention. The GSM network  200  includes a base station subsystem (BSS)  202 , a network subsystem (NSS)  204  and a General Packet Radio Service (GPRS) core network  206 . The BSS  202  can include one or more base transceiver stations (BTS)  208  and a base station controller (BSC)  210  communicatively linked via an A-bis interface. The BSS  202  allows a cellular telephone to communicate with a cellular network. BTSs are all interconnected to facilitate roaming from one cell to another via a process called handover, without losing the cell connection. 
     A packet control unit (PCU)  212  is shown as being in communication with the BSC  210  although the exact position of this can depend on the vendor architecture. The BSS  202  is connected by the air interface Um to a mobile terminal  214 . The BTS  208  are the actual transmitters and receivers of radio signals. Typically, a BTS for anything other than a picocell will have several different transceivers (TRXs) which allow it to serve several different frequencies or even several different cells (in the case of sectorized base stations). 
     The BSC  210  provides the intelligence behind the BTS  208 . Typically, a BSC  210  can have tens or even hundreds of BTSs  208  under its control. The BSC  210  handles allocation of radio channels, receives measurements from the mobile phones, and controls handovers from BTS to BTS (except in the case of an inter-MSC (Mobile Switching Center) handover, in which case control is in part the responsibility of the an MSC). One function of the BSC  210  is to act as a concentrator such that many different low capacity connections to the BTS  208  can become reduced to a smaller number of connections towards the MSC. Generally, this means that networks are often structured to have many BSCs  210  distributed into regions near the BTS  208  which are then connected to large centralized MSC sites. 
     The PCU  212  can perform some of the equivalent tasks of the BSC  210 . The allocation of channels between voice and data can be controlled by the base station, but once a channel is allocated to the PCU  212 , the PCU  212  takes full control over that channel. The PCU  212  can be built into the base station, built into the BSC, or even in some architecture it can be at a Serving GPRS Support Node (SGSN) site. 
     The BSS  202  is communicatively linked to the NSS  204  by an A interface. The NSS  204  is illustrated with a Mobile Switching Center (MSC)  216  connected via an SS7 network  218  to an HLR  220 . The AuC and the EIR, although technically separate functions from the HLR  220 , are shown together since combining them can be performed in the network. In accordance with the present invention, the HLR  220  can be configured to store historical location data associated with each subscriber. In addition, the HLR  220  can be configured to store CLAs and/or CLSAs for each subscriber. In addition to the HLR  220  or as an alternative, one or more databases  221  can be used to store the historical location data and the CLAs/CLSAs. 
     The combination of a cell phone  214  and a SIM card (not shown) creates a special digital signature that includes a subscriber number which is sent from the cell phone  214  to the nearest BTS  208  asking that the subscriber of a particular network be allowed to use the network. The request is passed on along the network of BTS  208  to the heart of a cellular network, the MSC  216 . The MSC  216  also routes all incoming and outgoing calls to and from the fixed-line networks or other cellular networks. When the user wants to make an outgoing call, another section of the MSC called the VLR checks whether the caller is actually allowed to make that call. For example, if the caller is barred for international dialing, a message to that effect will be generated by the VLR, sent along the network, and almost instantly back to the cell phone. 
     The HLR  220  provides the administrative information required to authenticate, register and locate the caller as that network&#39;s subscriber. Once the HLR  220  has received a log-on request, the HLR  220  immediately checks the special signature contained in the request against the HLR special subscriber database. If the subscription is current, the MSC  216  sends a message back to the phone via the BTS  208  that indicates the caller is allowed to access the network. The name or code of that network will appear on the LCD screen of the cell phone  214 . Once this network name message appears on the phone LCD screen, it means the caller is connected to the network and able to make and receive calls. 
     The HLR  220  registers which MSC the cell phone is currently connected to, so that when the network MSC  216  needs to route an incoming call to the cell phone number, the network MSC  216  will first check the HLR  220  to see which MSC is currently serving the cell phone. Periodically, the cell phone will send a message to the MSC indicating where it is, in a process called polling. The combination of the tracking function and the caller&#39;s unique digital signature allows the MSC  216  to route that call to the precise base station the cell phone happens to be connected to, and then exclusively to the cell phone, even if a number of other subscribers are simultaneously connected to that base station. 
     When traveling to another MSC coverage area while driving, for example, the HLR  220  is automatically updated, and continues to monitor where exactly it should route the calls should the caller then move within range of another base station. This routing procedure means that out of hundreds of thousands of subscribers, only the correct cell phone will ring when necessary. 
     In the present invention, the HLR  220  and/or the databases  221  are in communication with a CLA system  223 . The functionality of the CLA system  223  can be incorporated within the MSC/VLR  216  and/or other elements of the GSM network  200 . The CLA system  223  is responsible for acquiring historical location data for a subscriber and determining one or more appropriate CLAs and/or CLSAs for that subscriber. The location information and the resulting CLAs and/or CLSAs can be stored in the appropriate databases such as, for example, the HLR  220  and/or databases  221 . Exemplary methods for determining CLAs and paging MSs at these CLAs are described with reference to the remaining figures. 
     The NSS  204  has a direct connection to the Public Switched Telephone Network (PSTN)  222  from the MSC  216 . There is also a link from the NSS  204  to the GPRS core network  206  via a Gr/Gs interface although this is optional and not always implemented. The illustrated GPRS Core Network  206  is simplified to include an SGSN  224  (communicatively linked to the BSS  202  by the Gb interface) and a GGSN  226 . The SGSN  224  and the GGSN  226  are communicatively linked to each other by a private Internet Protocol (IP) network  228  called a GPRS backbone shown as the Gn reference point. A computer  230  is depicted as being in communication with the GPRS core network  206  via the Internet or a corporate network  232 . 
     Although a GSM network is illustrated, the exemplary paging system and methods described herein can be extended to any applicable network such as, but not limited to, a Universal Mobile Telecommunications System (UMTS) network, for example. 
     Referring now to  FIG. 3 , a block diagram of an exemplary method  300  is illustrated, according to the present invention. It should be understood that the illustrated methods with respect to  FIGS. 3-6  are not limited to the steps shown nor the order of the steps shown and are provided solely as a basis for teaching exemplary embodiments of the present invention. Accordingly, amendments to these methods and/or the addition, elimination, or combination of one or more steps may be made to achieve like results and still be within the scope of the present invention. 
     The method  300  broadly outlines the basic steps for arriving at the present invention. The individual steps are further defined in  FIGS. 4-6 , each of which is described below in detail. 
     The method  300  begins at step  302  and proceeds to step  304 , wherein historical location data is tracked and stored in a network database such as, for example, an HLR. It is contemplated that a separate database such as one particularly used to implement the storage needs of the present invention may alternatively or additionally be used to store the historical location data. The acquisition of historical location data and the storage thereof is described in further detail with reference to  FIG. 4 . 
     The term “historical location data” is used herein to describe data associated with a location (cell or group of cells) such as, but not limited to, the number of times a subscriber visits a location (frequency), the date, the time a subscriber is in a location (duration), the time of day, and the sequence of cells visited by a subscriber (sequence). 
     After the historical location data is acquired in step  304 , the method  300  proceeds to step  306  wherein at least one CLA is determined. This determination is described in further detail with reference to  FIG. 5 . 
     The method  300  then proceeds to step  308 , wherein a predictive algorithm is used, in an effort to minimize page attempts, to predict which CLA(s) and/or CLSA(s) the service provider should page. The predictive algorithm is described in further detail with reference to  FIG. 6 . After step  308 , the method  300  ends at step  310 . 
     Referring now to  FIG. 4 , an exemplary method  400  for tracking and storing location data is illustrated in accordance with one embodiment of the present invention. The method  400  begins at step  402  and proceeds to step  404 , wherein a subscriber&#39;s MS establishes communication with a base station. To aid in describing method  400 , reference will simultaneously be made to  FIG. 1 . Accordingly, the subscriber&#39;s MS  102  establishes communication with the base station  104  in cell  7 . At step  406 , the network cell identification is determined so that the network knows to which cell MS  102  is presently in communication. After the cell identification is acquired in step  406 , the method  400  proceeds to step  408  wherein the current date and time are acquired and stored. The date, for example, can include the day of the week, day of the month, month, and/or year. Again, storage for the date, time, and/or other location data can be provided by the HLR and/or a supplemental storage system such as a network database. 
     After the date and time are stored, a frequency counter is enabled at step  410 . The frequency counter is used to maintain the number of instances in which a subscriber&#39;s MS visits a particular cell or group of cells. The frequency counter is incremented in step  412  to account for the present visit. The frequency counter value is stored in step  414 . 
     At step  416 , the MS  102  terminates communication with the base station and the method proceeds to step  418  wherein the time is stored and the time duration is calculated. At step  420  it is determined if a handoff was performed. If a handoff was performed, the method  400  proceeds to step  422  wherein the MS  102  establishes communication with the new cell&#39;s base station. The new cell&#39;s identification is acquired in step  424  and the cell sequence is updated in step  426 . By way of example, a MS  102  could establish communication with a first cell (e.g., cell  7 ) and travel to a second cell (e.g., cell  8 ) thus establishing a sequence of cells, that is, cell  7  to cell  8 . As the MS  102  travels to new cells, this sequence is updated to reflect the new sequence. By way of example, path  106  could be established based on the sequence of cells  7 ,  8 ,  9 ,  13 ,  16 ,  17 , and  18 , thus establishing a CLA incorporating the cells of path  106 . The frequency, date, and time duration can be acquired and used to further define a CLA or CLSA. 
     After the sequence is updated in step  426 , the method  400  proceeds to step  408  wherein the date and start time is stored for the new cell. The method  400  continues in loop through the steps as previously described until no cell handoff is detected. If at step  420  it is determined that no cell handoff has occurred, then the method  400  proceeds to step  428  and the method  400  ends. 
     Referring now to  FIG. 5 , an exemplary method  500  for determining a CLA for a subscriber is illustrated, according to the present invention. The method  500  begins at step  502  and proceeds to step  504 , wherein the historical location data acquired during method  400  is loaded. At step  506 , the cells are determined for a CLA. 
     As previously described, the CLA system  223  and the HLR  220  and/or databases  221  acquire and store location data. Accordingly, the frequency as stored in step  414  can be used to determine to which cells the subscriber most frequently visits. As is also described in method  400 , a date, start time, and end time are acquired and used to calculate a duration. The date, start time, end time, and duration are used by the CLA system  223  to determine the cells for a CLA. The CLA system  223  can implement a priority scheme to prioritize the data types in making a CLA determination. The criteria used to establish the priority scheme can be any as selected by the mobile operator such as is appropriate for the operator&#39;s subscriber base. 
     At step  508 , a CLA is created from the determined cells. The CLA is stored in the HLR  220  and/or the database  221  in step  510  for later use. 
     The present invention may include a priority scheme for multiple CLAs associated with a subscriber. At step  512 , it is determined if multiple CLAs exist for the subscriber. If multiple CLAs exist, each CLA is assigned a priority level at step  514 . The priority level can be used to determine which CLA to page for a given situation. If only one CLA exists for a subscriber, the method  500  proceeds to step  516  and the method  500  ends. 
     Referring now to  FIG. 6 , an exemplary method  600  of a predictive algorithm for determining which location area to page, according to the present invention. The method  600  begins at step  602  and proceeds to step  604 , wherein the CLA(s) is acquired for a subscriber. The CLA(s) can be associated with a subscriber&#39;s International Mobile Subscriber Identity (IMSI). It should be understood that the paging scheme used by the present invention can be based on the subscriber&#39;s IMSI or a Temporary Mobile Subscriber Identity (TMSI). 
     At step  606 , it is determined if multiple CLAs exist. If multiple CLAs exist, then the method  600  proceeds to step  608  and the page-to location is determined. The page-to location can be determined based upon at least one of the priority level set in step  514  and the last known location. The last known location can be used to determine which CLA includes the most recent cell. The priority level can be used solely or in combination with the last known location to determine an appropriate page-to location. 
     After the page-to location is determined in step  608 , the method  600  proceeds to step  610  wherein the CLA is paged for the subscriber&#39;s MS. If a response is received at step  612 , the method  600  proceeds to step  614  and the method  600  ends. If, however, no response is received, the method  600  proceeds to step  616  and the next priority level CLA is paged. If a response is received after this subsequent attempt at step  618 , the method  600  proceeds to step  614  and the method  600  ends. If, however, no response is received, the method  600  proceeds to step  620 , wherein it is determined if an additional CLA is available. If another CLA is available then the method  600  reverts back to step  616  and the next priority CLA is paged. This loop continues unit either a response is received or no more prioritized CLAs are available. In some embodiments, a limit may be set by the mobile operator to limit the number of page attempts prior to executing a default page as illustrated in step  622 . Also, if no prioritized CLAs are available, the default page of step  622  is used. After the default page, the method  600  proceeds to step  614  and the method  600  ends. It is contemplated that the default page can be directed to a generic LA or a CLA. The default page may also include a default page of all LAs for an MSC. 
     If at step  606  it is determined that only a single CLA exists for a subscriber, the method  600  proceeds to step  624  and the CLA is paged at step  624 . If a response is received at step  626 , the method  600  proceeds to step  614  and the method  600  ends. If, however, no response is received at step  626 , then the default page is used at step  622 . The method  600  then proceeds to step  614  and the method  600  ends. 
     The law does not require and it is economically prohibitive to illustrate and teach every possible embodiment of the present claims. Hence, the above-described embodiments are merely exemplary illustrations of implementations set forth for a clear understanding of the principles of the invention. Variations, modifications, and combinations may be made to the above-described embodiments without departing from the scope of the claims. All such variations, modifications, and combinations are included herein by the scope of this disclosure and the following claims.