Abstract:
A method for conserving paging channel and access channel bandwidth is provided in a wireless telecommunications network (A). The network (A) includes: a plurality of cells ( 32 ) served by a mobile switching center ( 20 ) and including a paging channel for paging a mobile station ( 40 ) located within the cells ( 32 ) and an access channel by which the mobile station ( 40 ) registers its location with the network (A). The method includes: defining a first set of location areas including a plurality of paging location areas ( 50 ), each paging location area ( 50 ) including a plurality of cells ( 32 ); and, defining a second set of location areas including a plurality of registration location areas ( 60 ), each registration location area ( 60 ) including a plurality of paging location areas ( 50 ). As the mobile station travels, it registers via the access channel when entering one registration location area ( 60 ) from another registration location area ( 60 ), but it does not register via the access channel when entering one paging location area ( 50 ) from another paging location area ( 50 ) within the same registration location area ( 60 ).

Description:
FIELD  
       [0001]     The present inventive subject matter relates to the wireless or mobile telecommunications arts. Particular application is found in conjunction with paging a mobile station (MS), and the specification makes particular reference thereto. However, it is to be appreciated that aspects of the present inventive subject matter are also amenable to other like applications.  
       BACKGROUND  
       [0002]     Wireless or mobile telecommunications networks are generally known in the art. A MS (e.g.,. a mobile telephone or other mobile or wireless end user device) obtains service and/or access to the wireless network via an over-the-air radio frequency interface with a base station (BS). Each BS provides the over-the-air interface for and/or serves a particular geographic coverage area known as a cell. Typically, a plurality of base stations are operatively connected to and/or served by a mobile switching center (MSC) that is responsible for routing traffic for a particular MS to the appropriate BS currently serving that MS (i.e., to the cell in which the MS is currently located).  
         [0003]     The “mobility” in mobile communications is commonly achieved in part via two communication channels between the BS and MS, namely, a paging channel and an access channel. The paging channel is used to verify and/or establish the location of the MS within the network and to deliver incoming calls to the MS. The access channel is used by the MS for registration purposes, i.e., to report power-up of the MS, to report changes in the location of the MS, etc.  
         [0004]     Typically, a mobile service provider seeks to maximize the number of busy hour call attempts (BHCA) in order to serve an increasing number of mobile subscribers. One obstacle to achieving this goal, however, is the availability of sufficient paging channel bandwidth. While there are known ways to increase paging capacity, they often involve considerable expense and/or lead time, e.g., adding new bandwidth. Accordingly, it is desirable to optimize the usage of existing paging channel bandwidth.  
         [0005]     Historically, when an incoming call arrived at a MSC for a MS, all the cells in the entire MSC would be paged in order to contact the MS and deliver the call. That is to say, the MSC would signal all the base stations it served to transmit a paging signal over their paging channels to verify or establish the location of the MS within one of the cells. This approach, however, used a considerable amount of paging channel bandwidth insomuch as all the cells within the geographic region served by the MSC where paged for any given instance.  
         [0006]     A recent development is to partition the cells served by the MSC into a plurality of zones, i.e., groups of neighboring cells known as location areas (LAs), and begin paging only those cells in the last known LA of the MS being sought. While this reduces the load on the paging channel because fewer cells are instructed to page the MS for any given instance, the load on the access channel increases because registration messages are sent by the MS to the MSC every time an LA boundary is crossed. That is to say, in order for the MSC to know which LA the MS is in at any given time, the MS signals the MSC using the access channel each time it enters a new LA. Smaller LAs in turn mean that the LA boundaries are closer to one another, which in turn means that as a mobile subscriber travels they are more likely to cross more boundaries. Accordingly, increasing the number of LAs per MSC reduces the size of each LA and the load on the paging channel, but at the expense of increasing the load on the access channel. Service providers have found that creating more than a few LAs per MSC results in access channel overload. However, there remains the desire to reduce the paging channel load in order to support more mobiles and/or more services.  
         [0007]     Accordingly, a new and improved MSC partitioning system and/or method for a wireless telecommunications network is disclosed that overcomes the above-referenced problems and others.  
       SUMMARY  
       [0008]     In accordance with one embodiment, a method for conserving paging channel and access channel bandwidth is provided in a wireless telecommunications network. The network includes: a plurality of cells served by a mobile switching center and including a paging channel for paging a mobile station located within the cells and an access channel by which the mobile station registers its location with the network. The method includes: defining a first set of location areas including a plurality of paging location areas, each paging location area including a plurality of cells; and, defining a second set of location areas including a plurality of registration location areas, each registration location area including a plurality of paging location areas. As the mobile station travels, it registers via the access channel when entering one registration location area from another registration location area, but it does not register via the access channel when entering one paging location area from another paging location area within the same registration location area.  
         [0009]     In accordance with another aspect, a wireless telecommunications network includes: a plurality of base stations defining a corresponding plurality of cells, the cells being partitioned into a first set of location areas and a second set of locations areas, the first set of location areas including a plurality of paging location areas each having a plurality of cells therein, and the second set of location areas including a plurality of registration location areas each having a plurality of paging location areas therein; a paging channel for paging a mobile station located within the cells; and, an access channel by which the mobile station registers its location with the network, wherein the mobile station registers via the access channel when entering one registration location area from another registration location area and does not register via the access channel when entering one paging location area from another paging location area within the same registration location area.  
         [0010]     Numerous advantages and benefits of the inventive subject matter disclosed herein will become apparent to those of ordinary skill in the art upon reading and understanding the present specification.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The present inventive subject matter may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating example embodiments and are not to be construed as limiting. Further, it is to be appreciated that the drawings are not to scale.  
         [0012]      FIG. 1  is a diagram illustrating a telecommunications network suitable for practicing aspects of the present inventive subject matter.  
         [0013]      FIG. 2  is a diagram illustrating an exemplary MSC partitioning that embodies aspects of the present inventive subject matter. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0014]     For clarity and simplicity, the present specification shall refer to structural and/or functional elements, entities and/or facilities, relevant communication standards, protocols and/or services, and other components and features that are commonly known in the telecommunications art without further detailed explanation as to their configuration or operation except to the extent they have been modified or altered in accordance with and/or to accommodate the embodiment(s) presented herein.  
         [0015]     With reference to  FIG. 1 , a telecommunications network A includes a public switched telephone network  10  operatively connected to and/or in communication with a MSC  20  in the usual manner. The MSC  20  is operatively connected to and/or in communication with a plurality of base stations  30  in the usual manner. As is understood in the art, each BS  30  provides an over-the-air radio frequency interface for its respective geographic area or cell  32 . Selectively, a MS (such as the exemplary MS  40  illustrated) is provided telecommunication services and/or otherwise accesses the network A via the interface and/or BS  30  serving the cell  32  in which the MS  40  is located. In the usual manner two communication channels are selectively employed between the BS  30  and MS  40 , namely, a paging channel and an access channel. The paging channel is used to verify and/or establish the location of the MS  40  within the network A and to deliver incoming calls to the MS  40 . The access channel is used by the MS  40  for registration purposes, i.e., to report power-up of the MS  40 , to report changes in the location of the MS  40 , etc.  
         [0016]     While only one MSC is illustrated in  FIG. 1  for purposes of simplification and clarity, it is to be appreciated that the network A may in fact include any number of one or more MSCs that are similarly situated and/or arranged. Additionally, while three BS  30  and three corresponding cells  32  are illustrated in  FIG. 1 , it is to be appreciated that more or less than three base stations and/or cells may be similarly situated with respect to any of the one or more MSCs in the network A. That is to say, each MSC in the network A may optionally serve any number of one or more base stations and/or corresponding cells. Additionally, while only one exemplary MS is illustrated in  FIG. 1 , the network A optionally serves any number of one or more mobile stations similarly situated and/or arranged in any of the one or more cells  32 .  
         [0017]     With reference to  FIG. 2 , the cells  32  and/or geographic area served by the MSC  20  are zoned or partitioned in two different ways, i.e., into paging LAs  50  and registration LAs  60 . In the usual manner, each paging LA  50  includes a plurality of cells  32 . The registration LAs  60 , however, are generally larger than the paging LAs  50 . Suitably, each registration LA  60  includes a plurality of paging LAs  50 . As can be appreciated, unlike the traditional partitioning of an MSC having one set of LAs (i.e., the same set of LAs used for both paging and registration), the partitioning illustrated in  FIG. 2  has two sets of different LAs, namely, the set of relatively larger registration LAs  60  used for registration, and the set of relatively smaller paging LAs  50  used for paging. Accordingly, the larger registration LAs  60  result in relatively less frequent registration of traveling mobile stations and hence a reduced load on the access channel, while the smaller paging LAs  50  result in relatively fewer cells  32  being paged for a given instance and hence a reduced load on the paging channel.  
         [0018]     For example, as the MS  40  travels, it registers its current location with the MSC  20  each time it enters a new registration LA  60 , i.e., each time it crosses from one registration LA  60  into the next or each time it crosses a registration LA boundary. For example, the MS  40  registers with the MSC  20  serving its location by sending a registration signal to the MSC  20  using the access channel. In this manner, the MSC  20  is able to remember the most recent registration LA  60  from which the MS  40  registered. For example, the MSC  20  may store the last known registration information (including, e.g., the identity of the registration LA  60  from which the MS  40  last registered) in a location register or database  24  (see  FIG. 1 ). A time and/or date stamp for each of these registrations is also optionally maintained in the database  24 . In this manner, it can be determined how old the last registration is for the particular MS  40 . Suitably, registration does not take place when the MS  40  crosses from one paging LA  50  to the next within the same registration LA  60 .  
         [0019]     In addition to the last or most recent registration LA  60  from which MS  40  registered, the last or most recent cell  32  accessed by the MS  40  is also monitored by the network A, and mapped to the paging LA  50  containing that cell  32 . The identity of this last known paging LA  50  is optionally stored or maintained along with and/or as part of the information in the database  24 . Cell access events include those events where the MS  40  accesses a cell  32 , i.e., the MS  40  sends, receives or otherwise exchanges a transmission to, from or with a BS  30 . For example, a cell access event may include, registration of the MS  40 , the MS  40  receiving an incoming call, the MS  40  placing an outgoing call, the transmission of packet data to or from the MS  40 , short-message-service (SMS) receipt or transmittal, etc. For each of these activities, the network A is able to determine which BS  30  and/or cell  32  the MS  40  is using. Suitably, this cell location and/or identity is mapped to its corresponding paging LA  50  that is in turn captured and/or updated at each cell access event, e.g., by the MSC  20 . A time and/or date stamp for each of these captures and/or updates is also optionally maintained in the database  24 . In this manner, it can be determined how old the identity of the last known paging LA  50  is for the particular MS  40 .  
         [0020]     Suitably, when the MS  40  is being sought by the network A (e.g., when an incoming call arrives at the MSC  20  for the MS  40 ), an appropriate page is sent out for the MS  40  over the paging channel using a paging protocol that depends upon the information stored in the location register or database  24 . Depending upon if and/or when the page is answered, multiple pages may be attempted.  
         [0021]     For example, in a first paging attempt, if the last registration stored in the database  24  is more recent than a defined threshold, then the MS  40  is more likely to be in or near the paging LA  50  it entered when it entered the current registration LA  60 , otherwise if the last registration stored in the database  24  is older than the defined threshold, then the MS  40  is less likely to be in or near the paging LA  50  it entered when it entered the current registration LA  60 . That is to say, if the MS  40  had recently registered (i.e., crossed a registration boundary), then there is a certain level of confidence that the MS  40  is still in or near the cell  32  it used to register (i.e., within that corresponding paging LA  50 ). Conversely, if the MS  40  had not recently registered, then that level of confidence is somewhat lower. The paging protocol is therefore tailored accordingly. For example, if the MS  40  is deemed to have registered relatively recently (i.e., within the threshold), then the first paging attempt is merely sent out to the last known paging LA  50  stored in the database  24 , and optionally, if the MS  40  is deemed to have registered relatively long ago (i.e., outside the threshold), then the first paging attempt may be sent out to some larger area, e.g., the entire last known registration LA  60  stored in the database  24 . In this way, a wider area can be automatically paged for a more mobile MS  40 , while conserving both paging and access channel resources. Of course, if the MS  40  does not respond to the first paging attempt, a second attempted may be made, suitably scaled-up as appropriate, e.g., using a corresponding LA cluster (LAC) which includes the target LA plus all its neighboring LAs. For example, in the case of a recently registered MS  40 , the second page may go out to the last known paging LA  50  plus all its neighboring paging LAs  50 , while in the case of a relatively older registered MS  40 , the second page may go out to the last known registration LA  60  plus all its neighboring registration LAs  60 .  
         [0022]     It is to be appreciated that in connection with the particular exemplary embodiments presented herein certain structural and/or function features are described as being incorporated in defined elements and/or components. However, it is contemplated that these features may, to the same or similar benefit, also likewise be incorporated in other elements and/or components where appropriate. It is also to be appreciated that different aspects of the exemplary embodiments may be selectively employed as appropriate to achieve other alternate embodiments suited for desired applications, the other alternate embodiments thereby realizing the respective advantages of the aspects incorporated therein.  
         [0023]     It is also to be appreciated that particular elements or components described herein may have their functionality suitably implemented via hardware, software, firmware or a combination thereof. Additionally, it is to be appreciated that certain elements described herein as incorporated together may under suitable circumstances be stand-alone elements or otherwise divided. Similarly, a plurality of particular functions described as being carried out by one particular element may be carried out by a plurality of distinct elements acting independently to carry out individual functions, or certain individual functions may be split-up and carried out by a plurality of distinct elements acting in concert. Alternately, some elements or components otherwise described and/or shown herein as distinct from one another may be physically or functionally combined where appropriate.  
         [0024]     In short, the present specification has been set forth with reference to preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the present specification. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.