Abstract:
A method of and system for dynamically managing the registration and paging mobile units in a wireless system monitors a usage pattern for each mobile unit in the wireless system. Based upon the monitored usage pattern, the system sets a registration plan and a paging area plan for each mobile unit.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of wireless telecommunications, and more particularly to a method of and system for dynamically managing the paging and registration of mobile units in a wireless system based upon usage patterns. 
     DESCRIPTION OF THE PRIOR ART 
     Wireless services are being developed to serve a variety of telecommunications markets. These markets include paging, analog cellular, digital cellular, personal communications services, and general packet radio service (GPRS). The number of subscribers using these services is growing at a tremendous rate. 
     Wireless systems include an infrastructure of switching centers and base stations. Calls are delivered from the switching centers to the base stations by wire or fiber optic links, and from the base stations to mobile units via radio links. Because of the mobility of mobile units, it is necessary to know at least generally where in the system a mobile unit is located at a particular time, and to know more precisely where the mobile unit is located when it is necessary to deliver a call to the mobile unit. 
     In order to keep track of the location of mobile units, all mobile units are typically required to register with a serving mobile switching center. When a mobile switching center receives a call intended for a mobile unit, the mobile switching center pages the mobile unit. When the mobile unit responds to the page, the mobile switching center can deliver the call to the mobile unit. 
     Currently, all mobile units in a mobile switching center area are required to register when they power up or power down, or when the transmitted location area ID changes. Mobile units are also required to register periodically with their serving mobile switching center. Currently, all mobile units register periodically at the same frequency or on the same time schedule. For example, all mobile units in a particular serving mobile switching center area may be required to register every 15 minutes. Additionally, all mobile units in a mobile switching center area are paged in the same paging area. For example, a mobile switching center may page a mobile unit at its last register cell or sector and in a fixed number of adjoining cells or sectors. 
     The current system of registration and paging does not recognize differences in usage patterns among individual mobile units. For example, some mobile units may be characterized as low termination units. A low termination unit may have only a few, or even no, peak time terminations in any given day. Still, according to the prior art, such low termination units are required to register just like every other mobile unit. Additionally, some mobile units may be characterized as low mobility units. Such units either do not move at all in the system, or they remain in a relatively small area within the system. 
     With the tremendous growth of users of wireless systems, registration, and particularly periodic registration places a tremendous burden on the control channels. It is an object of the present invention to tailor registration and paging to the usage patterns of specific mobile units. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of and system for dynamically managing the registration and paging for mobile units in a wireless system. The system of the present invention monitors a usage pattern, such as the number of terminations over a selected time period or mobility, for a mobile unit. Based upon the monitored usage pattern, the system will determine the proper balance between registration and paging for that mobile unit. If the monitored usage pattern indicates an excessively high amount of registration compared to the termination and mobility of the mobile unit, the mobile may be told to alter the registration algorithm to reduce the number of registrations, for example, by telling the mobile to register half as often as other mobiles or by telling the mobile to not register at all. If the monitored usage pattern indicates a low amount of registration compared to the termination and mobility of the mobile unit, the mobile may be told to alter the registration algorithm to increase the number of registrations, for example, by telling the mobile to register twice as often as other mobiles. This increased registration would allow for reduced paging for those mobiles. According to the present invention, low termination or low mobility mobiles may be required to register less frequently. High termination or high mobility mobile units may be required to register more frequently. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a wireless system according to the present invention. 
     FIG. 2 is a plan of a mobile switch center area illustrating the control of paging areas according to the present invention. 
     FIG. 3 is a flowchart of processing according to a preferred embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and first FIG. 1, a wireless system is designated generally by  11 . Wireless system  11  includes an originating mobile switching center (MSC-O)  13 , which provides an interface between wireless system  11  and the public switched telephone network (PSTN), indicated generally at  15 . Subscriber and location information for mobile units, such as mobile unit  19 , is stored in a home location register (HLR)  21 . When mobile unit  19  enters into, or powers on in, an area served by a serving mobile switching center (MSC-S)  23 , mobile unit  19  registers with MSC-S  23 . Mobile unit  19  registers with MSC-S  23  by sending a registration message over a control channel to a base station  25  for the cell or sector in which mobile unit  19  is located. When mobile unit  19  registers, MSC-S  23  transmits location information for mobile unit  19  to a visitor location register (VLR)  27 . VLR  27  stores that information. When appropriate (e.g., for first time registrations, when the HLR requests, etc.), VLR  27  transmits the location information to HLR  21  and may ask HLR  21  to download subscriber information to VLR  27 . A short message service center (SMSC)  17  is provided to send short messages to mobile unit  19 . 
     After mobile unit  19  has registered with MSC-S  23 , mobile unit  19  will be instructed to register periodically with MSC-S  23 . This periodic registration enables MSC-S  23 , along with location registers  21  and  27 , to keep track of the location of mobile unit  19 . Also, if mobile unit  19  fails to register on its periodic registration schedule, MSC-S  23  may assume that mobile unit  19  has powered down or moved out of the area. According to the prior art, all mobile units in a serving MSC are required to register periodically on a standard schedule. 
     The area served by MSC-S  23  is illustrated diagrammatically in FIG.  2  and designated generally by the numeral  29 . Area  29  includes a plurality of cells or sectors  31  each served by a base station  25 . If mobile unit  19  registers, for example, in cell  31   a,  which is served, for example, by base station  25   a,  that location is recorded in VLR  27 . According to the prior art, if a call termination is received for mobile unit  19  at MSC-S  23 , the system will page mobile unit  19  in a standard paging area that could include cell  31   a  and in a fixed number of adjoining cells, for example cells  31   b - 31   c.    
     According to the present invention, and as will be explained in detail hereinafter, HLR  21  maintains usage pattern information for mobile unit  19 . Usage pattern information may include, for example, the number of call terminations to mobile unit  19  over a selected time period, or the mobility of mobile unit  19 . Periodically, according to present invention, HLR  21  makes an analysis of the usage pattern data for mobile  19 , and determines if mobile unit  19  presents special usage patterns, such as low termination or low mobility. If HLR determines that mobile unit  19  presents special usage patterns, then HLR  21  implements an enhanced registration and paging plan for mobile unit  19 . For example, if HLR  21  determines that mobile unit  19  is a low termination unit, which means that few or no call terminations are made to mobile unit  19 , HLR  21  will provide that information to VLR  27  and MSC-S  23 . According to the present invention, mobile unit  19  will be instructed, by means of a short message from SMSC  17  or the like, to make less frequent periodic registrations. For example, mobile unit  19  may be instructed not to make periodic registrations at all. Since mobile unit  19  is not required to make periodic registrations, when a call termination does arrive for mobile unit  19 , unit  19  may not be located in the vicinity of the cell or sector where it originally registered. Accordingly, according to present invention, MSC-S  23  may page mobile unit  19  in each cell or sector  31  of area  29 . 
     Additionally, according to the present invention, HLR  21  may analyze usage pattern data and determine that will unit  19  is a high termination unit. A high termination mobile unit is one that receives substantially more than an average number of terminations over a selected time period. According to the present invention, a high termination mobile unit may be instructed to register more frequently. For example, if the standard registration frequency is once every 15 minutes, a high termination unit may be instructed register at a frequency of once every five minutes, or perhaps the mobile will be told to register every time it changes control channel frequency. Since the system has more recent information with respect to the location of mobile unit  19 , upon receipt of a call termination for mobile unit  19 , MSC-S  23  can page mobile unit  19  in a smaller paging area. For example, if mobile unit  19  was last registered in cell or sector  31   a,  MSC-S  23  may page mobile unit  19  only in sector  31   a.    
     HLR  21  may determine that mobile unit  19  does not move around substantially and is therefore of low mobility. According to the present invention, the system instructs mobile unit  19  to register at a lower periodic registration frequency. For very non-mobile units, the registration frequency can be reduced to zero. Also, since the location of a low mobility unit is generally well known, the paging area may be reduced according to the present invention to a single cell. Conversely, if HLR  21  determines that mobile unit  19  is a high mobility unit, mobile unit  19  may be instructed to register more frequently than the standard, and it may be paged in a larger paging area. 
     Referring now to FIG. 3, there is shown flowchart illustrating one preferred embodiment of processing according to the present invention. Preferably, FIG. 3 processing is performed as a low priority background process. The system instructs the mobile unit to register periodically using the standard period from the control channel overhead message train, and instructs the MSC-S set the paging area is set at a standard area, at block  33 . As explained with respect to FIGS. 1 and 2, the standard registration period may be once every 15 minutes, and the standard paging area may be the cell or sector in which the mobile unit last registered and the contiguous cells or sectors. Then, the home location register monitors the number of terminations to the mobile unit over a selected time period, at block  35 . 
     Then, the HLR compares the number of terminations to mobile for the selected time period to preselected thresholds, at block  37 . In the embodiment of FIG. 3, there are a lower termination threshold and an upper termination threshold. Mobile units with fewer terminations than the lower threshold may be characterized as low termination units. Conversely, units with more terminations than the upper threshold may be characterized as high termination units. The HLR tests, at decision block  39 , if the number of terminations is less than the lower threshold. If so, the system implements an enhanced registration and paging plan, in which the HLR sends a short message service (SMS) message to the mobile unit instructing the mobile unit register less often, at block  41 , and instructs the MSC-S is instructed to page the mobile unit in a larger paging area, as indicated at block  43 . 
     If the number of terminations is not less than the lower threshold, the HLR tests, at decision block  45 , if the number of terminations is greater than the upper threshold. If so, the system implements another enhanced registration and paging plan, in which the HLR sends a short message service (SMS) message to the mobile unit instructing the mobile unit register more often, at block  47 , and instructs the MSC-S is instructed to page the mobile unit in a smaller paging area, as indicated at block  49 . 
     From the foregoing, it may be seen that the present invention overcomes the shortcomings of the prior art. The present invention provides a customized paging and registration plan for each mobile unit based upon measured usage patterns. The present invention reduces the burden on the control channel caused by paging and registration. 
     The present invention has been illustrated and described with respect to presently preferred embodiments. Those skilled in the art will recognize alternative embodiments, given the benefit of the foregoing disclosure. For example, alternative criteria and algorithms may be used for determining usage patterns, and greater or lesser levels of granularity may be employed in implementing the present invention. Certain features of the invention may be used independently of other features. Accordingly, the foregoing disclosure is intended for purposes of illustration and not of limitation.